Coral Reef Fish Stock Assessment Workshop-Interim Final Panel Report

February 10-13, 2004

Western Pacific Regional Fishery Management Council 1164 Bishop Street, Suite 1400

Honolulu, Hawaii 96813

Interim Final Panel Report

Panel Members:

Jerald Ault, Gavin Begg, Neil Gribble, Michel Kulbicki, Bruce Mapstone, Paul Medley

Coral Reef Fish Stock Assessment Workshop

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1. Introduction The Western Pacific Fishery Management Council manages coral reef fish fisheries in Hawaii, American Samoa, Guam, the Commonwealth of the Northern Mariana Islands and the U.S. Pacific Remote Island Areas, collectively known as the Western Pacific Region. To date no stock assessments have been done for any species in the coral reef fisheries.

The objective of the Coral Reef Stock Assessment Workshop was to develop a plan to improve data collection and assessment methodology to a point where reliable resource assessments can be obtained. Accordingly, the workshop aimed to:

“(1) review the state of the art of coral reef fisheries stock assessment and management methods; (2) determine the best methods for monitoring multi-species stocks to meet the Maximum Sustainable Yield (MSY) and over fishing control rules as required by the U.S. Magnuson-Stevens Fishery Conservation and Management Act for Federally managed fisheries; and (3) determine the status of and improve the availability and quality of coral reef fisheries data including criteria and parameters used in assessing fish stocks.”

Although the above were the aims at the beginning of the Workshop, they were far more optimistic than what proved possible or appropriate given the limitations of available fishery dependent, fishery independent or biological data needed for stock assessments and the infancy or absence of formal analysis of these data. Accordingly, the Workshop focused on the current sources and state of available data and the history of fisheries monitoring in order to consider their potential benefits and limitations with respect to future stock assessment of coral reef fisheries in the Western Pacific Region. This report, therefore, reflects these changes and details the outcomes and recommendations of the Panel from the Workshop. The authors’ intention is to provide direction and assistance to the Council for future assessment of the resource to satisfy the National Standards required by the U.S. Magnuson-Stevens Fishery Conservation and Management Act and to guide the development of robust sampling and monitoring strategies to underpin robust assessments in the future.

2. Characteristics of the Coral Reef Fisheries Coral reef habitat covers an estimated 6,120 sq. miles of the shallow ocean bottom around U.S. Pacific Island areas served by the Council. Near shore fisheries of the Western Pacific Region include a wide variety of reef and lagoon species and large and small pelagic fishes found within lagoons or near reef margins. A variety of methods are employed in the coral reef fisheries, including hand harvesting, hook-and-line, spears and a variety of nets and traps. The monitoring and regulation of near shore fisheries is mainly the responsibility of State or Territorial fisheries administrations, although there are some 4,200 sq. miles of lightly fished coral reef habitat that lie within the Federal waters of the Council’s jurisdiction. Table 2.1 lists the 2002 estimated domestic coral reef fish landings in the U.S. Pacific Islands.


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Table 2.1 Estimated coral reef ecosystem management unit species (finfish) landings for the Western Pacific Region, 2002.

Island area Landings (lbs)American Samoa 19,750CNMI 179,090Guam 177,030Hawaii 866,860Total 1,242,730

Near shore resources are caught for recreation, subsistence and commercial sales. Categorizing fishing activity into one of these different activities is extremely difficult in the Western Pacific Region, where people may have regular employment, but increase their earnings by occasional sales of fish when recreational or subsistence catches are more than required for personal consumption. In the Pacific Islands, nearly every person is a potential fisher and every village is a potential landing site. Even in Hawaii, a significant volume of the recreational catch is sold to the public along the roadside. This is another essential difference between the Western Pacific Region and other U.S. locations, where commercial and recreational fishers are strongly polarized and the commercial fishing community actively discourages fish sales by recreational anglers.

Contemporary participation and fishing practices in coral reef fisheries in the U.S. Pacific Islands have grown out of ancient traditions. Fishing for pelagic fish in offshore waters is constrained by the need for seaworthy vessels, distance to fishing grounds and weather. In contrast, near shore coral reef fisheries can be harvested with low capital outlay, and less time and risk. Relative to other fisheries resources in the U.S. Pacific Islands, coral reefs are more accessible and used by a larger and more diverse population of fishers, who employ a wider variety of gears. Near more populated islands, however, the impacts of fishing have been exacerbated by population growth and the introduction of modern, manufactured industrial fishing gear (e.g., monofilament nets, scuba).

Coral reef products that enter commercial markets typically undergo very little processing and the chain of sale is short, from harvesters to retailers to consumers. There are no known participants whose primary business is processing coral reef products. Wholesalers of coral reef products are also rare. The major use of coral reef resources is for subsistence, where the product moves directly from harvester to consumer, often within the same family or village.

2.1. American Samoa Most of the coral reef fisheries in American Samoa occur in near shore waters. Much of the bottom fishing activity by small boats is conducted on banks in the EEZ, and some of the shallow-water snappers and emperors harvested can be considered reef fish species. Currently, the catch from this fishery is minor (Green 1997). Aquarium or ornamental fish collection has occurred on a small scale in recent years. In recent years, coral reef fisheries have accounted for 62% of the annual catch of 154 mt and 70% of the $619,000 catch value. This estimate is low because it does not include the shoreline subsistence harvest or the shallow-water species of bottom fish, which are taken in the commercial small boat fishery. Virtually nothing is known about the reefs on the offshore banks because these are relatively inaccessible. It is assumed, however, that these are in better condition than the near shore reefs because they are deep and remote from most human activities. Evidence from recent fisheries statistics,


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scientific resource surveys, and interviews with village elders and fishers suggests that the more accessible coral reefs are seriously over fished. SCUBA-assisted fishing appears to be a major contributor to this problem.

2.2. Commonwealth of the Northern Mariana Islands Coral reef fisheries in the Commonwealth of the Northern Mariana Islands (CNMI) are mostly limited to near shore waters, especially off the islands of Saipan, Rota and Tinian. Finfish and invertebrates are the primary targets, but small quantities of seaweed are also taken. All of the recent data are for commercial landings, where typically 62-80 mt of reef fish are harvested each year. An unknown proportion of the bottom fish landings are shallow-water snappers, emperors, and groupers, which may be considered part of the coral reef fishery (Green 1997). Virtually no recent information is available for inshore subsistence and recreational catches of coral reef resources. This harvest is assumed to be substantial, especially in the more accessible areas like Saipan Lagoon. Little is also known of the coral reef fisheries in the northern islands of CNMI, but the catch by domestic fishers is generally believed to be minor. Poaching by foreign fishing boats may occur in some places (Green 1997). Offshore reefs receive little fishing pressure because of the limited range of the small boat fishery, except for the banks that are relatively close to the main islands, like Esmeralda and the extensive bank off Farallon de Medinilla, where a fishery for shallow-water bottom fish exists.

2.3. Guam Shore-based fishing accounts for most of the fish and invertebrate harvest from coral reefs around Guam. In recent years, the estimated inshore harvest has ranged from 38-108 mt. This estimate excludes highly variable catches of juvenile rabbitfish and bigeye scad by traditional fisheries that are still practiced seasonally (Myers 1993). While spearfishing is the principal method of harvest, it is highly seasonal because of weather conditions. The coral reef fishery harvests more than 100 species of fish, including those from the families Acanthuridae, Carangidae, Gerreidae, Holocentridae, Kyphosidae, Labridae, Lethrinidae, Lutjanidae, Mugilidae, Mullidae, Scaridae, and Siganidae (Hensley and Sherwood 1993). In the last few years, there has been an increase in commercial spearfishing using SCUBA at night. Catch rates have increased because of improved technology (high capacity tanks, high tech lights, and ‘bang sticks’) that allows spearing in deeper water (30-42 m). As a result, many larger species that have already been heavily fished in shallow-water, such as bumphead parrotfish, humphead wrasse, stingrays, and larger scarid species are now reappearing in the catches (Green 1997).

2.4. Hawaii In recent decades, there has been a notable decline in near shore fishery resources in the main Hawaiian Islands (MHI) (Shomura 1987). Akule (bigeye scad) and opelu (mackerel scad), more commonly referred to as “coastal pelagic” species, are the top species caught in Hawaii’s coral reef fishery. In the 2001 commercial catch data, these species accounted for nearly 80% of the coral reef catch. Of the coral reef species groups proper, surgeonfishes (Acanthuridae) had the highest catch, followed by goatfishes (Mullidae), squirrelfishes, soldierfishes (Holocentridae), unicornfishes (Naso spp.) and parrotfishes (Scaridae). The majority of the total commercial catch of inshore fishes comes from near shore reef areas around the MHI. Near shore reefs in the MHI are also the focus for commercial reef ornamental harvesting and black coral collecting (Friedlander 1996).


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2.5. Pacific Remote Island Areas Little is known about the present status of coral reef fisheries in most of the remote U.S. Pacific Islands, although anecdotal evidence suggests that these are mostly in good condition. There are no permanent residents on any of these islands, although on Wake Atoll and Johnston Atoll, there are temporary work forces that have a long history of recreational fishing and shell collecting. All of the more heavily fished areas at Johnston Atoll are located in near shore waters.

National Wildlife Refuges have been established at Baker, Howland and Jarvis Islands, Palmyra and Johnston Atolls and Kingman Reef. Natural resources are managed by the USFWS and access is by special use permit only.

3. Management Objectives The management objectives of the Western Pacific Regional Fishery Management Council’s Coral Reef Fisheries Management Plan (2001) are to:

• Foster sustainable use of multi-species resources in an ecologically and culturally sensitive manner, through the use of the precautionary approach and ecosystem-based resource management;

• Provide a flexible and responsive management system for coral reef resources that can rapidly adapt to changes in resource abundance, new scientific information, and changes in fishing patterns among user groups or by area;

• Establish integrated resource data collection and permitting systems, establish a research and monitoring program to collect fishery and other ecological information, and to collect scientific data necessary to make informed management decisions about coral reef ecosystems in the EEZ;

• Minimize adverse human impacts on coral reef resources by establishing new -- and improving existing -- marine protected areas, managing fishing pressure, controlling wasteful harvest practices, reducing other anthropogenic stressors directly affecting coral reef resources, and allowing the recovery of naturally-balanced reef systems. This objective includes the conservation and protection of essential fish habitats;

• Improve public and government awareness and understanding of coral reef ecosystems and their vulnerability and resource potential in order to reduce adverse human impacts and foster support for management;

• Collaborate with other agencies and organizations concerned with the conservation of coral reefs, in order to share in decision-making and to obtain and share data and resources needed to effectively monitor this vast and complex ecosystem;

• Encourage and promote improved surveillance and enforcement to support the plan’s management measures; and

• Provide for sustainable participation by fishing communities in coral reef fisheries and, to the extent practicable, minimize the adverse economic impacts on such communities.

No single stock-assessment model can be used to determine how to best meet all of these. Strategy Evaluation approach (e.g., Mapstone et al. 2003), combined with selected stock assessment methods, may be the most productive way to assess how well these and other multiple objectives are being met in the medium to long term.


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4. Overall Data Resources The Panel notes that there exists a considerable amount of data about the coral reef fisheries in each of the United States Western Pacific States and Territories. Data collected to date about the fisheries in each region, supplemented in places with ecological research data, are likely to provide a solid basis from which to design future data collection strategies that will address the likely key fisheries objectives of the Federal, State and Territory jurisdictions. In some cases, especially for the main islands of the State of Hawaii, there are long-runs of data, while in other Territories (e.g., American Samoa) comprehensive creel-based surveys apparently provide consistent data for all sectors of the fishery. In some cases, these existing data sets may be sufficient already for initial rudimentary stock assessments for some species.

It was clear from presentations, however, that the collection of data often had been irregular, inconsistent and subject to ad hoc changes in methods, usually associated with changes in staff. It was equally clear that the quality of existing data and the impacts of historical irregularities or changes in collection practices were difficult or impossible to assess because most of the data sets have not been analyzed or subjected to formal quantitative evaluation for consistency, precision, completeness, etc.

It is clearly important to get a data set to establish at least preliminary estimates of the status of coral reef fisheries. Clearly, this step should be viewed as a high and immediate priority that is required to address the mandate of National Standard 1 and to support longer-term efforts to manage the regional coral reef ecosystem. Accordingly, several of our recommendations that follow target the review and synthesis of existing data with a view to completing preliminary fishery or stock assessments.

4.1. Review, Synthesis and Analysis of Existing Data

Recommendation 4.1a: The Panel recommends that an immediate and primary priority should be the formal review and analysis of existing fishery dependent, fishery independent and biological data.

The Western Pacific Region coral reef fisheries program is currently supported by a disparate array of data sources (e.g., point-intercept creel surveys, commercial logbooks), sampling designs and information collection systems. The Panel felt strongly that the available state of fishery dependent data was the weakest aspect of the current spectrum of data collection. The problems associated with the collection of fishery dependent data mean that habitat and fishery independent stock biomass data currently being collected across the region can not be readily integrated with the fishery dependent data sources to improve stock assessments, unlike the situation in Florida and Australia.

A review of existing data will require the appointment of persons skilled in the collation and management of disparate data sets and expert in the analysis of fisheries data, preferably with a view to formal fishery and stock assessment procedures. Key tasks involved are likely to be:

• Collation of data from a range of departments, probably with disparate formats and in various stages of paper or electronic storage and error-checking;

• Standardization of the existing data by spatial and temporal references and to adjust for collection biases (such as those arising from use of different sampling gears or methods) to maximize the capacity to link data sets to each other and have confidence in inferences drawn from them;


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• Basic analysis of data characteristics to identify outliers or errors, completeness over the expected temporal and spatial domains, gaps and estimation properties (e.g., precision) of primary and derived variables;

• Evaluation of the potential to derive from the data parameters needed for formal assessment models (e.g., times-series of catch and effort), identification of shortcomings in parameter estimation (e.g., gaps in time-series) and exploration of options for compensating for such shortcomings by use of alternative or ‘quasi’ estimates (e.g., filling gaps in time-series by interpolation); and

• Analysis of the existing data to refine future stratified sampling and monitoring designs for the fisheries such that those sampling regimes provide for robust and precise estimates of catch and effort, stock biomass, changes in abundance, etc.

Such a review is an essential first step in planning for future data collection and monitoring, data analyses and formal stock assessments. This process will be necessary for all areas of existing data, including fishery dependent, fishery independent, biological and geographical data sets. This is a common theme noted throughout the workshop and considered to be a critical prerequisite for progress.

Recommendation 4.1b: The Panel recommends the hiring of a number of scientists (probably 3) skilled in data collation and data mining, sampling survey design, and population dynamics, modeling and stock assessment to process the existing data sets, complete preliminary assessments against National Standard 1 and design robust sampling strategies to support future management of the regional coral reef fisheries.

The complexity and difficulty of analytically reviewing existing data should not be underestimated. It is critical that people are appointed to these tasks who have high levels of expertise in data management and, more importantly, analysis of complex and ‘messy’ data. It is likely that a sequential approach will be most efficient, involving first the appointment of a data manager followed by the appointment or contracting of a skilled data analyst or assessment expert.

4.2. Coordination of Data Collection across Territories and Data Types

Recommendation 4.2a: The Panel recommends that there be renewed efforts to design fishery dependent and independent monitoring programs that are coordinated and consistent across the Western Pacific States and Territories and coherent among different sampling strategies (e.g., creel surveys, underwater surveys, logbook programs, etc.).

There is a clear need for the design of more rigorous and statistically reliable data collection programs for estimating coral reef fishery catch and effort. It appears that the current regional programs that have been implemented to provide these estimates in the Western Pacific Region may be suitable, but there has never been a systematic review and analysis of the efficacy of these programs to determine the precision of the estimates or their cost-effectiveness.

The Panel noted that there had been a strategy for implementing a consistent approach to creel-type surveys, but that the implementation of surveys had had varying success. These surveys seemed especially appropriate in areas with small, localized populations and easily targeted access points (e.g., American Samoa, CNMI, and Guam) where the creel surveys


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might effectively sample all sectors of the fishery. Such surveys should be actively supported to ensure greater security of data collection and constancy of methods. In more populous areas, such as the main islands of Hawaii, however, multiple complementary methods are required to estimate catch and effort characteristics across all sectors of the coral reef fisheries.

Following the review of existing data, we recommend that a comprehensive sampling design analysis be done to quantitatively evaluate design options for future monitoring and sampling strategies to address key fishery objectives (but note Section 4.6).

The Panel acknowledged that the particular social, cultural and logistic circumstances of each State or Territory will mean that adjustments to the basic design and methodological approaches will be necessary for successful implementation. Such adjustments, however, should be approached as planned departures from the desired template and should be motivated only by their necessity in order to effectively implement the monitoring locally. Such adjustments should not be subject to the whims of changing staff. Planning such adjustments should include formal consideration of the consequences of the changes for the type and quality of data collected, the capacity to easily and directly relate data to other data collected in the same or other regions and the impacts of proposed changes on the use of the data for planned analyses and fishery or stock assessments.

Recommendation 4.2b: The Panel recommends that the data collected under different monitoring programs should share sufficient common information in consistent formats to allow straightforward linking among data sets.

Key common fields should include, as a minimum, consistent spatial and temporal referencing, consistent species identifications and consistent measurement variables (e.g., fork length). The number of fields in common among different data sets should be maximized in a way consistent with sensible implementation of the various sampling methods. Wherever possible and meaningful, different monitoring programs should also follow consistent designs with sampling targeted at consistent sets, or at least some common subsets, of spatial and temporal domains and species.

There is likely to be great commonality in harvest species among the consumption fisheries and the sampling and analysis priorities are, accordingly, likely to be consistent among them. The aquarium fishery, however, is significantly different in many respects from the consumption fisheries (e.g., targeting small fish, different markets, shallow water, etc.). Thus, it is likely that the sampling requirements, relevant data and relationships between fishery dependent and fishery independent data for the aquarium fish fishery will be largely independent from those for the consumptions fisheries. Nevertheless, it will be important to maintain, as far as possible, consistency among the aquarium fish and consumption fishery datasets in some key basic variables such as time and place of sampling. This consistency of spatial and temporal referencing will become increasingly important as management increasingly encompass ecosystem management objectives.


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4.3. Specification of Management Units

Recommendation 4.3: The Panel recommends the clear articulation of the expected management units for the fishery to guide the refinement of monitoring and sampling strategies, but emphasizes also the importance of seeking maximum coherence of such strategies among management units.

The degree to which consistency of data collection can be relaxed among the U.S. Western Pacific States and Territories with negligible impact on the assessment outcomes will depend substantially on the domain over which data are to be aggregated and applied for assessments. Thus, the clear definition of the geo-political or administrative units of management will be central to the formulation of data collection guidelines. It also may be appropriate to treat specific areas within State or Territorial jurisdictions as separate management units for primarily administrative, cultural or historical use reasons (e.g., managing the main Hawaiian Islands separately from the northwestern Hawaiian Islands). The assessment and sustainability implications of defining distinct management units and treating data from them separately will depend on the degree of connectivity of harvested populations among such areas, either through adult migration or larval dispersal. Potential connectivity should be explored either by modeling credible scenarios of migration and dispersal or empirical verification of spatial structure in stocks (e.g., via tag-release-recapture, genetics, demographic studies, etc.).

The Panel emphasizes, however, that the identification of different management units (e.g., American Samoa, CNMI, Guam, and Hawaii) or areas within them (e.g., main and northwestern islands of Hawaii) should not be seen as a reason to relax unnecessarily consistency in the design and methods of data collection and analysis. There is great uncertainty about the degree to which populations of the same species in different States and Territories should be considered the same or distinct biological stocks and this uncertainty is unlikely to diminish in the near future. It is important, therefore, to retain as far as possible the option for integrating assessments across distinct management units if it is considered that the different management units are managing sub-units of a common biological stock. The success of such integration will hinge largely on the consistency of the data available from each management unit.

4.4. Straddling Stocks

Recommendation 4.4: The Panel recommends that the data collected for the bottomfish and coral reef fisheries for common species should be combined within management units for assessment purposes and that future monitoring programs be coordinated across the fisheries.

The Panel felt that the distinction between the bottomfish fisheries and the (shallow water) coral reef fisheries was likely to be artificial for at least some species that were common to both fisheries. While there is no evidence available to assess whether the deep water (>100 fathoms) and adjacent shallower water populations of a species are part of a single stock, the Panel considered it most prudent to assume at this time that they are.

A corollary of this recommendation is that the needs for data consistency discussed above also should be applied across the fisheries. It may be that various recommendations for additional data collection for bottomfish made in a recent workshop (Ralston et al. 2004) could be built into a broader and more comprehensive monitoring design for reef fish and bottomfish.


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The Panel also considered that wherever feasible, the management of such straddling species should be approached as a single issue within each management unit, rather than management via separate regimes distinguished only arbitrarily by the depths and gears of operation.

4.5. Spatial and Temporal Resolution

Recommendation 4.5: The Panel recommends that some common, unambiguously nested spatial and temporal referencing schemas be adopted for the design and implementation of all data collection programs.

It became clear that the spatial resolution with which data were collected varied widely among sampling or monitoring programs, with method, among the States and Territories and over time. Such disparate scales will complicate the combination of data and increase uncertainties in analyses and estimators derived from those data. Wherever possible, such prescribed scales should retain consistency with existing scales at which data have been collected, but such consistency should not be used as an excuse to avoid implementing a coherent set of spatial references for future sampling. Similar issues arise in relation to temporal scales of sampling.

4.6. Operational Objectives

Recommendation 4.6: The Panel recommends that immediate action be taken to articulate appropriate short, medium and long term operational objectives for the coral reef fisheries in all Western Pacific States and Territories.

The Panel noted that operational objectives did not currently exist outside of National Standard 1. Objectives that are available for the coral reef fisheries of the Western Pacific Region (e.g., Section 3 above) are general in nature and tend to be administrative objectives rather than outcome objectives related to the desired future status of the stocks or their harvest. Such objectives are not sufficiently specific or quantitative to guide the optimal design of targeted, efficient and rigorous sampling and monitoring programs.

Operational objectives will (should) define the criteria by which adequacy of sampling and monitoring designs are assessed and refinements to data collection strategies are identified and funded. For example, it will be important to document the expected sensitivity (statistical power) of monitoring programs to detect changes in key fishery statistics that would be considered sufficiently important to trigger management action and design data collection strategies to meet those expectations. The magnitude of those critical changes should be prescribed by the operational objectives for the fisheries.

It will be important to include in the formulation of operational objectives the aspirations and needs of the range of stakeholders in the fishery. Doing so will require a structured process of developing specific objectives in consultation with each of the stakeholder groups (Mapstone et al. 2003).

4.7. Priority Species

Recommendation 4.7: The Panel recommends that priorities be attached to information about each species in order to direct limited sampling resources and ensure that high quality, adequate data are gathered for at least some of the most important harvested species.

The coral reef fisheries of the Western Pacific Region are highly multi-species in all States and Territories and in all sectors (commercial, recreational, subsistence, charter, head boat,


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aquarium). It will be impossible to routinely collect extensive data on the harvest and biology of all species.

Further, data about different species will have different priorities. The basis of priorities attached to species is most likely to be related to their relative abundances in the catch in each State or Territory, but might also include consideration of cultural, ecological or economic importance and perception of risk from over exploitation. It is important to note that designing sampling and monitoring programs optimally for selected species is a matter of logistical necessity, not desirability. The intent should be to obtain the maximum taxonomic resolution feasible in routine monitoring programs and compromise resolution only so far as is necessary for reliable implementation of monitoring. It will remain important, however, to collect periodically data on the species composition and relative abundances of each species in the catch to supplement the data gathered routinely at poorer taxonomic resolution.

4.8. Standardization of Data Storage and Management

Recommendation 4.8: The Panel recommends that structured, managed databases be developed in parallel with the review of existing data and the development of future sampling strategies.

An often neglected aspect of the collection and analysis of long-term fishery data sets is their coherent storage in properly managed, accessible relational databases that are either centralized or distributed in a coherent, managed network. It seems that there is no such data management strategy in place for data relevant to the coral reef fisheries of the U.S. Western Pacific Region. The development of databases to coherently accommodate data from diverse fishery dependent and independent sources will not only ensure security of data and straightforward data access, but also should provide a quality control mechanism over the continued collection and collation of data with consistent basic properties and key variables.

Combining data from several sources collected by diverse methods (e.g. catch, effort, UVC, video, catch samples, etc.) within the same data base is usually difficult but an important part of streamlining assessment processes. Insistence on common conventions for key fields (e.g., spatial and temporal references, taxonomic precision) from which to link different data will obviate most obstacles to data integration and should be an integral aspect of the design of future sampling programs and databases. Further, Geographical Information Systems (GIS) increasingly are being used in assessment processes and provide powerful tools for the presentation of results to disparate audiences. Accordingly, the design of future databases should include structures to facilitate easy linking of data to GIS applications.

There are various approaches to data coordination, ranging from highly centralized databases to distributed database structures. The Panel makes no assessment of appropriateness of any one method for the Western Pacific Regions, but urges that explicit evaluation of alternative be an early step in database development.


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5. Fishery Dependent Data Integrated fishery dependent data collection systems from coral reef fish fisheries can provide accurate, precise and cost-effective estimates of total fishery catch and fishing effort from both commercial and recreational fishing sectors. Fishery dependent data collection systems can be designed to produce information to be consistent and compatible with other fishery data sources (e.g., fishery independent systems) in support of stock assessments. To obtain such reliable fishery dependent information that allows estimation of total harvest and the contributions by each of the harvest sectors, however, requires a rigorous and well-designed sampling program of fleet sectors (or gears) and their catches (i.e., numbers and weight of fish). Concise quantification of fishery catches and the associated fishing effort by each gear (measured in the appropriate units) distributed over the unit stock area over unit time provides important and fundamental contributions to stock assessment models. Data of the appropriate rigor is necessary to be reflective of stock dynamics and responses to exploitation. Thus, there is a fundamental requirement for development of a consistent and reliable data collection regime to obtain time series of effort by gear type, catch by species by gear type, species composition, and details about the data collection and any associated problems therewith. A critical component of comprehensive catch-and-effort sampling efforts is a sound biological data catch-sampling program. Catch-sampling provides an important means to obtain estimates of the size, age, and sex and maturity composition for each species of reef fish occurring in the catches over a specified time period (see Section 7).

The current fishery dependent data collection systems for coral reef fisheries statistics in the Western Pacific Region for each of the States and Territories (i.e., American Samoa, Guam, Northern Mariana Islands, Hawaii, and U.S. Pacific remote island areas) are shown in Table 5.1.

Recommendation 5.1: Mechanisms for obtaining reliable estimates of catch and effort need to be investigated, and the best possible means relevant to different sectors evaluated. These analyses should include cross-validation of vessel catch reports obtained from logbooks or the various point-intercept creel surveys with sales records from wholesale dealer-processors.

Currently in the Western Pacific Region, only the State of Hawaii requires that participants in the commercial sector obtain marine fishing licenses to operate in the coral reef fishery. This license system provides an important count of the total fleet size (i.e., sampling universe) of the various components of the sectors of the commercial fishing fleet in Hawaiian waters. Data that accurately define the sampling universe are critical to the effective design of sampling surveys. The Panel felt that it would be advisable to institute some kind of licensing and vessel registration in other Territories of the Western Pacific Region where these mechanisms currently do not exist. Fisher licenses and vessel registrations may provide convenient proxies for representing the magnitude of effective fishing effort when no or limited direct effort data are available.

Another important issue raised by several Participants at the Workshop was a suspected significant and substantial non-reporting of both commercial logbook and recreational fishery catches, perhaps as large as 50% or more of the total harvest. There was also substantial concern voiced regarding the accountability and reliability in reporting of catch and effort by


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different fishing sectors (particularly the recreational fishing sector) which would suggest the need for substantial improvement in the overall reporting of data.

The Panel felt that several mechanisms for obtaining reliable estimates of catch and effort need to be investigated, and that the best possible means relevant for different sectors be evaluated. Some ways that reporting may be improved could involve penalties, incentives, education, and making reporting formats more consistent with the actual operations of the fishery sectors. One mechanism acknowledged by Participants that could help to improve and cross-validate reporting of vessel catches may be the study of the relationship between vessel catch reports obtained by the various point-intercept creel surveys with those obtained from records generated from fish purchases by wholesale dealer-processors. In addition, co-management and participatory programs should be developed on a regional basis to improve the overall process of participation in data collection programs that in turn would improve the accuracy and precision of the basic data. Other suggestions involved examination of comparative studies that have been conducted by the Secretariat of the Pacific Community (SPC) (consumption surveys) to evaluate the catch taken by the subsistence fishery.


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Table 5.1 Current fisheries data collection systems for obtaining fishery dependent coral reef

fisheries statistics in the Western Pacific Region.

American Samoa

Guam Northern Mariana Islands

Hawaii U.S. Pacific Remote Island

Areas Responsible Agency:

Department of Marine and Wildlife

Resources (DMWR)

Division of Aquatic and

Wildlife Resources (DAWR)

Division of Fish and Wildlife

(DFW)

Division of Aquatic Resources (DAR)

U.S. Fish and Wildlife Service (USFWS) and

NOAA Fisheries

Fishing License Required:

No No No Yes, Commercial Marine Fishing License.

No Special Use Permit

Required Primary Collection System:

(Offshore) Boat-based access point creel surveys (six

locations on Tutuila and one location on

Manu‘a Island.)

Presently, no inshore creel

(Offshore) Boat-based access point creel

surveys

Inshore creel survey

(Offshore) Boat-based access point

creel surveys

Since 1996, no inshore creel

survey

Mandatory Commercial Catch Report (C-3 Form)

None

Sampling frequency:

Two weekdays and one weekend per

week

Average: Bi-weekly sampling

Opportunistic Fishermen required to submit monthly to DAR

None

Data Collected: Interviews for: number of

fishermen, area fished, total hours fished, gears used,

total species caught, weight in pounds, number of pieces

per species, disposition of

species, length of fish, price per pound for each

species

Interviews for: number of

fishermen, area fished, total hours fished, gears used,

species caught, weight in

pounds, number of pieces per

species, disposition of


species

(Offshore only) Interviews for:

number of fishermen, area

fished, total hours fished, gears used,

species caught, weight in pounds, number of pieces

per species, disposition of


species

For each trip, licensee must report: commercial

license number, boat name and registration number, area or buoy

fished, type of gear used, species caught, number caught, pounds caught, pounds sold, value of sales, port of landing

None

Other Fishery Validation Systems:

Mandatory Commercial

Purchase System (purchase receipt

“trip ticket” for fish businesses on

Tutuila)

Guam Fishermen’s

Cooperative fish purchase invoices

and Voluntary “trip ticket” invoices

Dealer Invoicing System

summarizing sales ticket receipts from

all purchasers of fresh fish products

Mandatory commercial marine dealer report detailing the weight,

number and value of each species of marine life purchase, transferred, exchanged or sold and

the name of current license number of the commercial licensee

None

Year Began: 1970 1982 1982 1950’s Not Applicable Year Revised: -- -- -- 2001 Not Applicable


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6. Fishery Independent Data

6.1. Evaluation of Current (existing) Surveys Recommendation 6.1: Collate all historical and current UVC (Universal Visual Census) data

into a coherent database, evaluate the properties of those data and standardize catch (e.g. hand line, long line) and non catch (e.g. UVC, video) methods for differences in sampling biases and spatial and temporal references.

Within each territory there have been considerable surveys and experimental work using fishery independent methods. Such surveys include those by NOAA and by the various Fishery or Parks Services as well as a number of studies by independent sources such as Universities (e.g. by MSc and PhD students from U. of Hawaii and U. of Guam) and the Army Corps of Engineers. Much of this information is not readily available, especially for work performed before 1990. These data could be useful for many purposes, such as providing historical insights into the species composition and some species parameters (e.g., size frequencies, density, and recruitment). As with other types of data, these data need to be catalogued, "decoded," assessed for quality and consistency, and collated into accessible databases. This process is likely to be especially difficult for the fishery independent data because of the disparate sources of the data, diversity of ownership of the data and the variety of methods used in different studies. Standardizing these data sets for different methodological biases will be especially important.

With only a couple of exceptions (e.g. work by Walsh et al. targeted at the aquarium fish fishery in Hawaii), most of the work performed so far in U.S. Territories in the Pacific using fishery independent methods has not been intended for direct use for fishery purposes. Most such studies used UVC only and were restricted to shallow reef areas. Their aims were usually to obtain assessments of the structures of the reef fish communities and their relationships to environmental variables on a comparative spatial and temporal basis.

These historical data may be useful for fisheries assessment purposes via the use of length frequencies, abundances, species richness or population or biomass densities in rudimentary biomass estimation or assessment procedures for a number of species or species groups (trophic groups, size groups, guilds). Additionally, fishery independent information from remote, lightly fished areas (e.g., the northern Marianas Islands, the Northwestern Hawaiian Islands) or areas closed to fishing (such as Marine Protected Areas) might provide proxies for the "initial" status of stocks in neighboring but exploited islands (e.g., the Main Hawaiian Islands). Because the design criteria for such surveys were not usually related to fisheries issues or stock assessments, however, much of these data may be of relatively little use for assessments of harvested species and of most use for future assessments of ecosystem impacts of fishing.

6.2 Estimation of Methods’ Capacities and Biases for Fisheries Assessment Purposes Recommendation 6.2: The Panel recommends the formal evaluation of the relative benefits

and biases of alternative and complementary methods for fishery independent monitoring of coral reef fisheries.


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Coral reef resources are usually not limited to one habitat. Many harvested species inhabit habitats over a wide depth range, moving among habitats either diurnally or ontogenetically. It is therefore important to sample as much as possible of the range of habitats used by such species. It is usually not possible, however, to sample all habitats effectively with the same method. In such cases, it may be necessary in the sampling design to allow for the use of different methods in different habitats and it is particularly important to cross-calibrate those methods to facilitate legitimate combination of data derived from them. Such calibrations might be achieved by ensuring some overlap in areas sampled by each method or via dedicated, designed studies where both methods are used at the same places and times specifically to compare their sampling properties.

6.2.1 Non-catch Methods A number of non-catch, non-destructive, fishery independent methods should be considered for future fishery related monitoring programs. The primary methods are Underwater Visual Census (UVC), remote video and associated methods, and acoustic methods.

The types of data that can be gathered from UVC have been noted previously (Section 6.1) and their use historically in the Western Pacific Region means that there is the potential for methodological and data continuity in the use of UVC in future. UVCs have a certain number of limitations which need to be addressed. In particular this method (or rather family of methods) is not useful for some species groups, is limited at present to 20m depth, and is susceptible to biases introduced by behavioral responses of fish to divers.

Underwater video and associated methods currently are little used in the U.S. Western Pacific States and Territories. Video and related methods such as submarines and Remotely Operated Vehicles (ROVs) have application in areas beyond the reach of UVCs, but there are a number of technical and logistic problems in the use of these methods. At the moment, video and underwater recording devices have relatively poor definition compared to the human eye, have relatively narrow fields of view, are costly to purchase and operate and recorded data take considerable time to process. Alternatively, they have a number of advantages over UVC, including the extended depths and times at which they can work and their capacity to work in low light.

Acoustic methods are not currently in use in the Western Pacific States and Territories. Acoustics have been used with success in a number of situations, especially for surveys of pelagic and semi-pelagic species and for a restricted number of benthic species. Acoustic methods are unlikely to useful for assessing stocks of reef dwelling species but might be useful for some of the pelagic and semi-pelagic species (in particular Carangidae, Scombridae and Clupeidae) which comprise important components of the present reef fish catches in shallow waters in the Hawaiian Islands. These methods, however, do not yield direct estimates of abundance (fish/m²) or density (g/m²) and their calibration is often difficult.

The above methods are likely to be particularly useful in circumstances where destructive methods are unlikely to be allowed. For example, non-destructive methods are likely to be the only methods available for assessing the status and utility of MPAs closed to extractive uses and other fishery closures.

6.2.2 Catch Methods Fishery independent catch surveys apparently have not been used in the Western Pacific States and Territories for fisheries assessment purposes. Catch survey methods used elsewhere in the


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Pacific include hand lines, bottom longlines, nets (gill nets, trammel nets and fyke nets), traps and trawling.

Provided catch survey methods are chosen to resemble the methods used in the normal operations of the fishery being assessed, they have the advantage of providing results that can be compared directly to commercial and recreational fisheries being assessed. They also provide a means of gathering biological specimens in a structured way, but with similar selectivity to that effective in the relevant fishery. These methods generally provide indirect measures of abundance or biomass density, similar to the CPUE estimates derived from fishery catch and effort data. According to consistent designs, catch surveys done in conjunction with non-catch surveys, also provide a means of better linking non-destructive sampling data to fishery dependent data. As with any sampling methods, it is important to standardize catch survey methods and to verify their likely biases before extensive use.

6.3 Standardization of Methods (Catch and Non-catch) Recommendation 6.3: The Panel recommends the adoption of a preferred suite of methods to

sample the major harvested species in all relevant habitats, provided that such methods have been subject to rigorous evaluation of their appropriateness and sampling properties.

There is an obvious lack of uniformity in the types of UVC methods used in the past by various U.S. Western Pacific agencies studying coral reef fishes. There also appears to have been little or no effort to coordinate the various methods to standardize their application. It is recommended that a preferred suite of fishery independent methods (including catch and non-catch methods) be developed for use in future fishery independent monitoring.

It is important also that the relative biases of alternative or complementary methods be verified and documented analytically and methods applied only for species for which those methods are likely to support robust estimates of key variables (e.g. Harmelin et al., 1985; Bohnsack and Bannerot, 1986; Cappo et al. 1996; English et al. 1997; Samoilys, 1997; Labrosse et al., 2002).. For example, UVC may yield good estimates for the abundance, density or size frequencies of some species (e.g. Scaridae, Acanthuridae, Serranidae) but perform poorly for others (e.g. Lethrinidae, Lutjanidae, Holocentridae). Similarly, catch methods are usually heavily biased towards some species (e.g. lines catch only carnivores). All methods, including UVC, are subject to some form of selectivity that means that the data from them usually should be interpreted as only relative measures rather than completely representative and absolute measures of those variables. Nevertheless, many such data are highly relevant as indicators of changes in the fisheries or the harvested stocks.

Recommendation 6.4: The Panel recommends that a formal training program for the preferred sampling methods be designed and provided to all staff expected to collect data for coral reef fisheries assessments.

Standardization of methods should also include thorough field training in the application of each method to ensure consistent results from multiple observers and reduce the risk of confounding observer-related biases with variation among places or times of sampling (Thompson and Mapstone 1997). New automated technologies, such as laser size and ranging systems (Luo J. and Ault J. in prep.), pocket digital underwater cameras, and video sampling software, should also be considered in order to improve standardization of sampling among places and times.


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Recommendation 6.5: The Panel recommends that assessment and sampling strategies for coral reef fisheries in the U.S. Western Pacific Region be coordinated with similar activities by neighboring states, especially in the far western Pacific where several neighboring states are likely to be sharing common fishery resources.

The SPC has established a standard for counting reef fish using UVC and is currently developing a standard for habitat surveys associated with commercial reef fish surveys. This standard will be in application in 15 countries or territories of the South Pacific by 2005. The appropriateness of adopting these standards for routine monitoring in the United States Western Pacific States and Territories should be investigated, especially since most of the U.S. Pacific Territories are located close to other island nations that almost certainly harvest the same fish stocks and that are likely to adopt these standard methods. Consistency of sampling strategies among neighboring territories (whether or not of U.S. affiliation) will streamline syntheses of assessments among jurisdictions sharing the same resources.

6.4 Survey Designs Good sampling design is essential to get robust results. It was noted by the Panel that previous UVC work had generally blocked sampling by habitat, but that the objectives of such studies were focused on making comparative assessments of the relative status of different habitats, rather than to derive estimates of populations sizes over all habitats (as would be important for stock assessments). Though population estimates may be derivable from these surveys, significant improvements in the precision of estimates will be obtained by appropriate stratification of sampling across habitats according to relative abundance of target species and /or fishing intensity (if known) (e.g., Ault et al. 2002). The near-complete mapping of shallow water habitats by NOAA and NOC will provide a great aid to stratification of future assessment-related sampling and monitoring programs and the existing data on relative densities of relevant species will provide initial estimates of variances in estimates from which to formally stratify sampling among the mapped habitats. Again, the Panel emphasizes the importance of careful design of future sampling and monitoring programs to meet specific operational objectives (refer Section 4.6) and the need to recruit personnel skilled in assessment-related sampling design to analyze existing data.

7. Biological and Ecological Data Recommendation 7.1: The Panel recommends that a comprehensive review be undertaken of

the extent and quality of existing biological and ecological data, and subsequent compilation and integration of these data for those species that are part of the coral reef fisheries.

A suite of fundamental biological and ecological parameters are required to meet the needs of various stock assessment models, but only disparate sources of information exist for some species throughout the Western Pacific Region. Furthermore, although this information exists in various scientific publications, reports, postgraduate theses and their associated data sources, the studies from which such data arose and the species studied were not done with the intention of providing input data for stock assessments.

The Panel considered a good starting point for a comprehensive review was the modeling study by DeMartini et al. (1993) who conducted a literature search on relevant biological


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information from various postgraduate theses of the Universities of Hawaii and Guam and other data sources for Hawaiian coral reef fish species. Such a review could point to shortfalls in the data, particularly with respect to the priority species for the coral reef fisheries, and direct future research designed to provide parameter estimates for fishery and stock assessments. Examination of data, both local and elsewhere, would in the short-term provide an indication of availability of fundamental input parameter estimates necessary for various assessment models and derivation of biological and fishery reference points that are required to fulfill the obligations of the National Standards.

Recommendation 7.2: The Panel recommends that a data collection program and targeted studies be implemented to gain fundamental biological information on priority species in the coral reef fisheries.

The Panel felt that the program of biological sub-sampling of catches at present appeared to be limited, inadequate, and in some cases, non existent. Depending on data quality and availability, priority should be given to collecting basic population dynamics information on the priority species needed for evaluating the status of the fishery. This collection program should be considered relative to short-, mid- and long-term objectives of understanding the fishery and related ecosystem. The highest priority should be to gain fundamental information on age, length, weight, maturity, natural mortality and sex ratios of the priority harvested species that would enable basic calculation of the National Standards reference points.

It is important, however, that such catch-sampling programs be designed to limit the extent to which they are viewed as burdensome by the fishery sector but supply at least sufficient detail to conduct the required stock assessments. It may also be advisable to consider collection of complementary environmental data that may correlate with catches and/or species abundances, which could be important for future statistical modeling and ecosystem assessment efforts.

The Panel recommends that a second level of priority be given to obtaining auxiliary information to improve our understanding of key species and ecosystem processes. Targeted studies to obtain data on spawning seasonality and location, fecundity, habitat associations, recruitment, movements and stock structure of the priority species should all be considered. Notably, some of these studies have already commenced (e.g., Ulua Tagging Project, population genetics investigations of coral reef fish), with some to be completed in the near future (e.g.., U.S. Coral Reef Ecosystem Mapping Project).

Finally, the Panel notes that for the development of more prospective and complex assessment models in the future, including multi-species and ecosystem approaches, information will be needed on behavior, diet, predator-prey interactions, early life history stages and associated levels of connectivity and dispersal among reefs and islands. The acquisition of such information, however, inevitably will be a medium-long term goal and should not compromise the immediate initiatives to fulfill less ambitious assessment objectives.

Recommendation 7.3: The Panel recommends that until sufficient data becomes available for thorough assessments, surrogates data be applied for those species and regions where data is not available locally.

The scarcity or patchiness of historical data from areas in most of the Western Pacific States and Territories where fisheries are most developed means that several key parameters for assessments (e.g., maximum age, maximum size, natural mortality) will be difficult or impossible to estimate directly for those areas. Comparative analyses of data for target species already collected (or readily collectable in the short term) from lightly exploited areas such as


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the Northwestern Hawaiian Islands and Marine Protected Areas throughout the Western Pacific Region, however, may provide surrogate estimates of such key parameters to allow preliminary assessments to be done. Clearly, careful consideration needs to be given to the implications of extrapolation of data across variable environments or among species, but the qualified use of surrogates may be the only way to approach formal assessments in the near term. The Panel acknowledges the political issues that are involved in undertaking destructive sampling in highly sensitive protected areas to obtain data for some of the above variables, but stresses that the long-term benefits outweigh any potential adverse short-term impacts of limited destructive sampling (e.g., Mapstone et al. 2004).

Recommendation 7.4: The Panel recommends that resources be dedicated to establishing a local base of technical expertise for obtaining essential age and reproductive based population dynamics parameters.

The importance of age and growth data for evaluating the status of harvested resources cannot be over-stated. One of the reasons for the lack of age data for coral reef species throughout the Western Pacific Region appears to be persistent dogma that coral reef fish species cannot be aged reliably. The Panel considers, however, that there is sufficient evidence now available from throughout the Indo-West Pacific and Caribbean to refute that doctrine. Standardized and validated methods for ageing coral reef fish exist and numerous species have been successfully aged in coral reef ecosystems around the world (e.g., Ferreira and Russ 1994; McBride 2001; Williams et al. 2003), including from Hawaii (Radtke et al., University of Hawaii), American Samoa (Craig et al. 1997, Acanthurus lineatus; Wilson unpub. data, Lutjanius kasmira, Cephalopholis urodeta, Acanthurus olivaceus, Cetoscarus bicolour, Scarus forsteni, Epinephelus tauvina, Ctenochaetus binotatus, Chromis spp., Holocentridae) and the Commonwealth of the Northern Mariana Islands (Trianni unpub. data, Lethrinus rubrioperculatus).

The above and other studies have indicated that coral reef fish species tend to exhibit a wide range in length at age and, importantly, are extremely long-lived with flat-topped growth curves where asymptotic sizes can extend across several decades. Such growth trajectories signal important limitations of basing assessment models on length data alone. Consequently, the Panel considers it imperative that basic age and growth information be collected via a structured sampling program for the priority harvested species. Similarly, collection of information for determination of reproductive schedules is considered a high priority for robust assessments because of the variation in reproductive strategies being uncovered for coral reef fish.

The Panel acknowledges, however, the fiscal and personnel resources required for such a program and recommends the Council consider the most cost-effective means for obtaining reliable age and reproductive data in the short term, whether that be contracting permanent staff to work within established local facilities or outsourcing expertise on a contractual basis. In the long term, however, the Panel recommends that the Council build capacity and expertise in these areas of research and monitoring that are critical for any lasting commitment to stock assessment.


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8. Analytical and Modeling Approaches Recommendation 8.1: The Panel recommends that the reviews of the available fishery

dependent, fishery independent and biological data include, but not be limited to, trialing preliminary stock assessment approaches.

The analytical/modeling approaches ultimately used for stock assessments will depend on the availability and quality of commercial catch and effort data, and parallel UVC data, for each Western Pacific State and Territory. Where possible, both fisheries dependent and fisheries independent data should be used to give a better picture of the health of the stock(s). In a manual for assessing fish stocks on Pacific coral reefs, Samoilys (1997) and authors therein outline techniques for obtaining abundance estimates from “scaled-up” UVC data, combined with CPUE estimates from line fishing. The biomass dynamics model suggested by Samoilys was similar to that outlined in the Bottom Fish Stock Assessment Workshop (Ralston et al. 2004). Ault et al. (2003) in a stock assessment in the Florida Coral Reef ecosystem also used a combination of UVC and catch and effort data, which may serve as a template for future assessments of coral reef fisheries in the Western Pacific Region.

It would be beneficial also if compatibility is maintained with stock assessment approaches recommended in the Bottom Fish Stock Assessment Panel Report (Ralston et al. 2004). That report details Spawning Potential Ratio (SPR) and Dynamic Production Models (DPM) methods for use in a parallel fishery that likely impacts on at least part of the coral reef fish stocks. It may be possible to use these techniques as a template for a ‘first pass’ assessment of coral reef fish species, where there are sufficient data available from the shallow water coral reef fisheries for species that are harvested in both regimes. A major difference between the bottomfish and coral reef fish fisheries assessments is the availability of the UVC data for reef fish, which should be incorporated if possible in assessments of the coral reef fisheries.

By necessity the analysis and assessment for each Western Pacific State and Territory will be limited by the available data, and only simple robust assessments will be possible where there are few data. More sophisticated modeling will only become feasible as more comprehensive data sets become available. Bayesian assessment approaches might allow formal use of data and information sources which would otherwise be difficult to include in preliminary assessments. Existing information on growth, mortality and other single species model parameters may be used best as prior probability distributions for Bayesian-like assessments rather than as individual point estimates for more conventional approaches.

Recommendation 8.2: The Panel recommends the use of a variety of stock assessment models, where there are appropriate data sources, and to try new approaches where possible.

A convergence of model results would give more confidence in predictions of stock status and likely yields. It is not clear what models will be most appropriate, however, without looking in detail at the available data and trying to fit various models to them. Analysts should search out patterns in the data which can be exploited for estimating model parameters. Depletion and recovery events in time series should allow important population parameters governing fishing mortality and stock productivity to be estimated.

If there is no contrast naturally occurring in the catch time series, it might be introduced through management action. Temporary area closures or enforced reductions in fishing effort may be very informative as to the behavior of the resource, but must be carefully monitored.


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Spatial heterogeneity in coral reefs might be used to obtain such time series experimentally in small areas, without depleting the entire resource (e.g., Mapstone et al 2004).

Dynamic Production Models Biomass dynamic models are among the simplest dynamic population models. They do not model the population structure, so cannot provide any advice on management controls that affect the age, size or sex structure of the population (such as gear controls or specific closures to protect spawners, recruits and so on). The approach will enable, however, National Standard 1 to be addressed, as it provides estimates of biomass and fishing mortality with appropriate reference points. As with the Bottom Fish Stock Assessment, biomass can be combined not only over the population structure, but over species as well, providing an empirical description of the gross yield from a management unit.

Biomass dynamics (and other “depletion”) models in theory require total catch data (all removals) as the driving force behind changes in the population. Total catch may be estimated with error, but significant bias or uncertainty in the estimates may lead to poor results. The model can be fitted using any number of indices of abundance, such as catch and effort for each gear and UVC data. Catch and effort data potentially come from a number of data sets for disparate fisheries ranging from spear fishing, reef-line and gillnet fisheries. The primary data are recorded in commercial log-books and creel surveys. There needs to be a standardization of effort data across gear types and reporting sources or, preferably, separate catchability parameters fitted for each fishery as part of the stock assessment model.

An initial assessment of MSY for the Bottom Fish Stock Assessment was conducted using this approach (Ralston 2004). The 1996 Bottom Fish Assessment employed bootstrapping and re-estimation of model parameters to estimate values of catchability. Subsequently, this estimate was refined by field experiments. In the absence of refinement in parameter estimates, a coral reef fish stock assessment would need to go through a similar exercise to obtain estimates of catchability.

Given that it is unlikely that there will be sufficient commercial catch and effort data for any State or Territory other than Hawaii, a standard Dynamic Production Model (DPM) approach will be limited at best.

The Panel also recommends that a Bayesian approach to fitting DPM be applied where data are appropriate. Bayesian approaches allow greater flexibility but more consistent use of information. PFSA software (Medley 2003) is a coral reef stock assessment example where various separate data sources can be used to provide different sources of information on different sets of parameters within a Bayesian framework. Information sources could include fisher knowledge, fishing experiments, UVC, meta-analyses of previous work and shared observations from other locations. This approach can be used to reduce uncertainty or at least identify what critical information is missing. Other Bayesian software for stock assessment is also widely available (e.g. Punt and Hilborn 2001) and other simple approaches might be applicable (e.g., Medley 1998).

Where there is no depletion event in the time series data, the model might still be fitted based on a Bayesian approach and informative priors derived from meta-analyses of population parameters from previous research or, for example, from monitoring MPAs immediately after closure up to an unexploited state. The assessment would result in an informed ‘best guess’ as


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to the state of the resource even if the population indices lacked contrast or the time series were very short. If total catch can be estimated well, this approach is recommended.

UVC Biomass Estimation The basis of this method is to estimate the biomass for a suite of transects (or other standardized sampling units) and then “scale-up” this estimate to the area of the habitat being surveyed (Samoilys 1997). This estimate would complement the DPM estimates for the “aggregate stock,” as described in the Bottom Fish Stock Assessment Workshop (Ralston et al. 2004). On a species by species basis, UVC will provide size frequency data that can be used with length based assessment models. These data and procedures may be of particular use in assessment of the aquarium fish fishery stocks, and others, though note the reservations about length-based procedures expressed by the panes in Section 7.

Structured Models

Spawning Biomass and Spawning Potential Ratio SPR is a “data-based” stock assessment method used to assess the condition of the stock relative to an assumed unfished state. As usual, there are underlying assumptions about data-quality such that the actual catch and effort or abundance statistics accurately reflect the true values in the fishery.

This method also was recommended in the Bottom Fish Stock Assessment Workshop (Ralston et al. 2004) and may be applicable for some coral reef fish species in the Western Pacific Region. It may be possible to derive Spawning Potential Ratios (SPR) from comparisons of fished to unfished areas. The unfished areas could provide the required estimate of a “base catch rate” or population abundance estimate if survey data were available for species harvested elsewhere (see below).

Recruitment Index Models Some limited population structure might be added to assessments using recruitment index models. Recruitment indices may be obtained from many sources, including CPUE from particular gears or locations that have a high proportion of small fish or from length data taken seasonally from catches. Such models can be very effective and represent a step on the path towards more complex age structured models.

Recruitment index models have been used widely in Caribbean spiny lobster stock assessments (FAO 1999, Medley and Ninnes 1997). The method used seasonal recruitment and behavior of fishers immediately after a closed season. It is likely fishery specific patterns of exploitation might be similarly used in other fisheries where they can be found. Exploratory analysis of the current data together with discussions with fishers may identify information suitable for use as a recruitment index for some coral reef species.

Length and Age Based Approaches (Single Species)

Where a good time series of length based data for a priority species exists, and there is a reasonable correlation between length and age (e.g. some coastal pelagic species of Carangidae), then length-converted age based models could be used. Biological parameters such as growth, age-at-maturity, and total mortality (fishing and natural) would be needed, although proxies some of these parameters might be obtained from the literature for similar stocks.


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Length-based assessments also might be used to estimate natural and fishing mortality. They require at least one sample of length data from the population. For example, length-converted catch curves obtained from fisheries and compared to lightly fished areas should give indications of the relative exploitation rate. These methods are reasonably robust, and as long as length can be converted to age with reasonable precision, selectivity is constant with length and recruitment has been relatively constant. The equilibrium assumption may be reasonable if CPUE can be shown to be reasonably constant over a number of years.

A further possibility is the suite of length/age cohort assessment models that can be applied to time series of length/age distributions. Ault et al. (2003) is an example of an age structured model fitted to catch at length data for the Florida Hogfish in a coral reef ecosystem.

These models allow reasonably accurate assessment of recruitment and fishing mortality at age (selectivity) and recruitment. Such models may be a necessary step to establish a reliable stock-recruitment relationship and links between populations. As well as catch-at-length and indices of abundance, these models will require good conversion between length and age (for example, an age-length key based upon routinely collected age data or a growth model), so fish length needs to be reliably informative of age. The latter has proved not to be the case for many coral reef species in the Indo-Pacific region.

Catch-at-age models, however, suffer a number of disadvantages. They are difficult and time consuming to carry out. The large number of parameters needed may not be estimated well, and various data problems may require considerable statistical expertise to address. For example, parameter estimates are usually very heavily correlated and hence cannot be estimated well. An estimate of natural mortality is required, and the assumption that it is constant may be unreasonable for coral reef fish and result in misleading assessments. Therefore, simpler models may often give more reliable results.

Multifan-CL (and others) allow direct fitting to catch-at-length data. The model integrates the growth and mortality parts of an age-structured dynamic model and fits parameters using a Bayesian procedure. While a growth model is not required, demands for data are high and it is unlikely that the model will fit well without cohort modes in the catch-at-length data.

For future assessments collections of aged samples from priority species would allow direct application of age-based models with less uncertainty in parameter estimates than would arise from applying length-age conversions.

Habit mapping and estimates of carrying capacity

This is a GIS based approach which superimposes the known CPUE or UVC abundance estimates onto a detailed map of the available habitat then interpolates (or extrapolates) the “carrying capacity” of given habitat types. This gives a very rough estimate of total “potential” abundance for a species.

Multispecies-VPA

These models allow the natural mortality of each species to be linked to the abundance of other populations. The approach requires trophic information, as well as catch-at-age data for all species being modeled. This may be an alternative to other ecosystem approaches, but the data requirements are particularly large. Multispecies-VPA has not been attempted on highly diverse fish communities, but such models represent a step towards ecosystem approaches.


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Ecosystem Approaches There are a number of ecosystem models available or currently being developed. For trophic models that are based on biomass flows, rather than carbon, nitrogen or energy flows are more amenable to the type of data collected to date within the Western Pacific Region Fisheries (Polovina 1984 and 1993). ECOPATH EwE, for example, is a software platform that is readily available and well documented (e.g. Walters et al 1999, Gribble 2000). Detailed habitat mapping, data on fish community composition, spatial distribution of biomass and trophic transfer rates are the core information needed for ECOPATH. Estimates of consumption, production and diet for each trophic guild to be modeled are critical information requirements. While considerable habitat mapping information and some data on fish community structures exist for the Western Pacific Region, the necessary consumption and production information will likely take some time to accumulate. The Panel notes that such studies are probably best suited to post-graduate research. Ecosystem models focusing on the monk seal and French Frigate Shoals (Polovina 1984, Frank Parrish this workshop) already exist and might provide a platform for expansion to full-scale region wide models.

Finally, although fully coupled hydrodynamic, spatial, age-structured, predator–prey simulations of ecosystem responses to fishing and environmental change (e.g., Ault et al. 1999) are data intensive, these are the target to aim for in the longer term.


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9. Summary Recommendations In summary, the Panel provides the following recommendations for the data collection and analysis and assessment of the coral reef fisheries in the Western Pacific Region:

• Define appropriate short, medium and long term operational objectives for the coral reef fisheries in all Western Pacific States and Territories [Urgent & Critical];

• Appoint appropriately qualified personnel to a) collate and b) analyze the existing available data relevant to coral reef fisheries of the Western Pacific Region and design rigorous future fishery sampling and monitoring programs [Urgent & Critical];

• Following collation and preliminary analyses of existing data, contract an appropriately qualified expert in stock assessment to review formally the available data and recommend future options and data needs for reef fish stock assessments [Urgent & Critical];

• Complete a comprehensive review of the extent and quality of the existing biological and ecological data, and subsequent compilation and integration of these data for those species that are part of the fishery [Urgent & Critical];

• Attach priorities to information about each species in order to direct limited sampling resources and ensure that high quality, adequate data are gathered for at least some of the most important harvested species [Urgent & Critical];

• Design fishery dependent and independent monitoring programs that are coordinated and consistent across the Western Pacific States and Territories and coherent among different sampling strategies (e.g., creel surveys, underwater surveys, logbook programs, etc.) [Urgent & Critical];

• Implement the best possible mechanisms for obtaining reliable estimates of catch and effort for each sector of the coral reef fisheries [Urgent & Critical];

• Obtain fundamental information on age, length, weight, maturity, natural mortality and sex ratios of the priority species that would enable basic calculation of the National Standards reference points [Critical];

• Trial a variety of stock assessment methods and models, where there are appropriate data sources, testing new approaches where possible [Critical];

• Adopt common, unambiguously nested spatial, temporal and taxonomic resolution and referencing schemas for the design and implementation of all data collection programs [Critical];

• Ensure that the data collected under different monitoring programs share sufficient common information in consistent formats to allow straightforward links to be established among data sets [Critical];

• Develop structured, managed databases hand-in-glove with the review of existing data and the development of future sampling strategies [Critical];


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• Define the expected management units for the fishery to guide the refinement of monitoring and sampling strategies [Important];

• Combine the data collected for the bottomfish and coral reef fisheries for common harvest species within management units for assessment purposes [Important];

• Initiate collection of age and growth information via a structured sampling program for some of the priority species [Important];

• Establish a local base of expertise on ageing and other biological-ecological methods and build-up capacity in these areas for research and long-term monitoring [Important];

• Development of a formal training program for the preferred sampling methods to be provided to all staff expected to collect data for coral reef fisheries assessments [Important];

• Apply surrogates for those species and regions where data is not available, that is either based on existing data from the Hawaiian Islands and Territories or other coral reef ecosystems [Optional];

• Obtain auxiliary information to improve understanding of priority species and ecosystem processes [Optional];

• Coordinate the assessment and sampling strategies for coral reef fisheries in the U.S. Western Pacific Region with similar activities by neighboring states [Optional];


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10. References

Ault, J.S., Bohnsack, J.A., and Meester, G.A. 1998. A retrospective (1979-1996) multispecies assessment of coral reef fish stocks in the Florida Keys. Fishery Bulletin 96(3):395-414.

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Documents

Coral Reef Fish Stock Assessment Workshop-Interim Final Panel Report