Summary of the blue cod (Parapercis colias) catch and ...docs.niwa.co.nz/library/public/FAR2006-61.pdf · difference caused by various form types (e.g., TCEPR forms record tow by

New Zealand Fisheries Assessment Report

2006/61 December 2006

ISSN 1175-1584 Summary of the blue cod (Parapercis colias) catch and effort data and standardised CPUE analysis from the BCO 4 fishery, 1989–90 to 2004–05 D. Fu D. J. Gilbert M. J. Manning S. J. Baird

Summary of the blue cod (Parapercis co/ias) catch and effort data and standardised CPUE analysis from the BCQ 4 fishery,

1989-90 to 2004-05

D.Fu D. J. Gilbert

M. J. Manning S. J. Baird

NIWA Private Bag 14901

Wellington

New Zealand Fisheries Assessment Report 2006/61 December 2006

Published by Ministry of Fisheries Wellington

2006

ISSN 1175-1584

© Ministry of Fisheries

2006

Citation: Fu, D.; Gilbert, D.J.; Manning, M.J.; Baird, S.J. (2006).

Summary of the blue cod (Parapercis colias) catch and effort data and standardised CPUE analysis from the BCO 4 fishery, 1989-90 to 2004-05.

New Zealand Fisheries Assessment Report 2006/61.40 p.

This series continues the informal New Zealand Fisheries Assessment Research Document series

which ceased at the end of 1999.

EXECUTIVE SUMMARY

Fu, D.; Gilbert, D.J.; Manning, M.J.; Baird, S.J. (2006). Summary of blue cod (Parapercis colias) catch and effort data and standardised CPUE analysis from the BCO 4 fishery, 1989-90 to 2004-05.

New Zealand Fisheries Assessment Report 2006161. 40 p.

This report characterises the commercial fishery (BCO 4) for blue cod (Parapercis colias). Catch and effort data were used to determine the temporal and spatial distribution of trends in the fishery from 1989-90 to 2004-05. Standardised CPUE indices were extracted from these data to monitor the changes in relative biomass in the fishery.

The commercial catch in BCO 4 is dominated by target cod pot fishing with an insignificant amount of bycatch from rock lobster potting and bottom longlining. The catches are almost exclusively taken off the Chatham Islands (Statistical Areas 049, 050, 051 and 052) with an autumn-winter peak (MarchSeptember). The effort in the fishery is influenced by the timing of the coexisting rock lobster fishery in the same area.

The lognormal and Poisson-gamma models were used to produce standardised CPUEs for the target pot fishery. Based on diagnostics, the Poisson-gamma model provided better fits for the data but the two models gave similar results. CPUE indices were produced for each of the Statistical Areas 049, 050,051, and 052 separately as well as for all the areas combined.

The CPUE analyses were restricted to daily records rather than the number of pot lifts as a measure of fishing effort because of inconsistent recording of effort number on the catch-effort forms, and also to statistical area as the smallest spatial unit because position data were not reported.

The analyses showed that the relative biomass of blue cod in BCO 4 remained relatively stable from 1989-90 to 1996-97, then steadily increased to 2001-02 except for the drop in 1999-2000, and remained stable after that. The indices for each of the Statistical Areas 049-052 in general exhibited an increasing trend with large inter-annual variability in the late 1990s. The relative biomass declined in the early 1990s in Statistical Area 049 and increased consistently over the past 15 years in Statistical Areas 050 and 051, except for the drop in 1994-95 in 051. The relative biomass declined sharply in Statistical Area 052 in 1991-92 but has rebuilt to a level in recent years similar to that in 1990-91. In general, the trends were similar among the four statistical areas.

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1. INTRODUCTION

The blue cod (Parapercis colias) fishery is predominantly an inshore domestic fishery off Southland and the Chatham Islands. BCO 4 (Figure 1) supports the second largest commercial fishery for blue cod. The landings were below 400 t per annum before 1992-93 and have increased over the last decade (Ministry of Fisheries Science Group 2006). The annual landings after 2001-02 exceeded 700 t and doubled those of the early 1990s, approaching the TACC of 7S9 t (Ministry of Fisheries Science Group 2006) (Table 1). Blue cod are caught mainly through target pot fishing in Statistical Areas 049-OS2 off the Chatham Islands (Figure 2); these areas produced over 9S% of the total blue cod landings in BCO 4. The seasonal pattern of the blue cod fishery is largely influenced by the timing of the effort in the rock lobster fishery operating in the same area because historically most blue cod fishers were primarily rock lobster fishers (Ministry of Fisheries Science Group 2006).

Blue cod are bottom dwelling fish that are often found in areas of reef or foul ground; thus, survey methods found to be useful for sampling blue cod include line fishing, diver transects, remote video transects, and pot surveys. Potting surveys of commercial blue cod fisheries have been undertaken in the Marlborough Sounds (for example, Blackwell 1997, 1998) Banks Peninsula (Beentjes & Carbines 2003), and Dusky Sound (Carbines & Beentjes 2003).

National surveys of recreational fishers have indicated that catch rates are declining in many areas (see Beentjes & Carbines 200S). However, recreational fishing around the Chatham Islands is not included in these "national" surveys, so there is little documented information available for recreational blue cod fishing in BCO 4.

Previous studies also included the summary of catch and effort data of blue cod in BCO 3 and BCO S (Langley 200S) and the characterisation of the Southland blue cod fishery from 1991 to 1996 (Warren et a1.1997). These studies found that several factors of the blue cod population (size, sex, and abundance) varied between localised areas. However, no CPUE standardisation was performed for the BCO 4 fishery and, therefore, both combined and separate CPUE standardisations for the four main Statistical Areas 049-OS2 were carried out and are described in this report.

The objective of the research under the Ministry of Fisheries (MFish) project BC0200S/03 is "To characterise the BCO 4 fishery by analysing existing commercial catch and effort data and data from other sources; and to make recommendations on appropriate methods to monitor or assess the status of this fish stock".

To address this objective, analyses are carried out in this paper:

a) to determine the annual distribution of blue cod catches by fishing method, target speCIes, statistical area and month, and

b) to identify subsets of the fishery which have stable presence in time and space; and to extract standardised CPUE indices based on those "representative" fisheries

2. METHODS

2.1 Data set

The data for the analysis were extracted from the MFish catch-effort database warehou and included catch effort and landing data from trips that landed blue cod in BCO 4 from 1989-90 to 2004-0S. The catch effort data included 14686 records from Catch Effort and Landing Return forms (CELR), 1868 records from Trawl, Catch, Effort and Processing Return forms (TCEPR), and 1433 from Lining Catch Effort Return forms (LCE). The landing data included 10 440 records from Catch Landing and Return Trip form The (CLR) and 112 records from the landing part of TCEPR forms. The data were

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groomed and stratified before further analysis using the procedure proposed by Starr (2003). The procedure makes the catch and effort recorded on different form types comparable and uses the landed catch to correct the estimated catch on a proportional basis. A detailed introduction to Starr's procedure and its implementation was given by Manning et al. (2004) and only the main steps are summarised below.

a) Invalid or suspicious values (null or out of range) from the catch effort and landing table are replaced through data imputation.

b) The data in the catch effort table are stratified (grouped) by a unique combination of trip, date, fishing method, statistical area, and target species. The estimated catches and fishing effort within the same stratum are aggregated.

c) The records in the catch effort table are linked to those in the landing table based on trip/fish stock (the variable fish stock is available in the landing table but is derived from statistical area in the catch effort table). The greenweight reported for a fish stock by a trip in the landing table is then allocated among the catch and effort strata that are mapped to the same triplfish stock, using the estimated catch or the fishing effort of the strata to obtain the proportion for the allocation.

Missing values of statistical area, target species, and fishing method were replaced by the most common value from the same trip/date (Table 2). A few records in the landing data containing suspiciously large green weight values were identified and fixed by reference to the corresponding processed weight. The stratification aimed to unify the fishing effort on a daily basis and eliminate the difference caused by various form types (e.g., TCEPR forms record tow by tow data whereas CELR forms are completed on a daily basis.). The loss of information was minor because most data were recorded on CELR forms and therefore corresponded to daily fishing events (Table 3). The trips from the catch effort and landing data were well matched (Table 4) and the statistical areas are contained within the Quota Management Area of BCO 4 (Figure 2), thus minimising the loss of catches in the process of green weight allocation.

We provide a brief summary of the results of the data compilation (Table 5) in which the data were compared through different stages of the grooming-stratification-allocation process to show that the integrity of the data was not compromised. The relationship between estimated catches and allocated greenweight for each fishing year is presented (Figure 3).

Further analyses were based on green weight, not estimated catch. ("Catches" and "landings" are used interchangeably, referring to greenweight rather than estim~ted catch in the following sections unless explicitly specified.) However, there should not be any major difference because the allocation algorithm ensured that the allocated greenweight preserved the ratio of the estimated catch between strata (at least within the same trip) and, unlike bycatch dominated fisheries, the zeros of the estimated catches in a target fishery are more reliable.

About 20% of the CELR records were reported from rock lobster areas 940-943, where blue cod were either taken as bycatch or targeted in conjunction with the rock lobster fishery. These records were reassigned to the corresponding general Statistical Areas 049--052.

2.2 Description of the fishery

The catch and effort data were summarised to provide a description of the dynamics of the fisheries. The temporal-spatial distributions of blue cod catches were examined. The connection between the rock lobster and the blue cod fishery was briefly investigated. Subgroups of the data which were representative of the fisheries were identified with the selection of the core vessels that operated more regularly than other vessels in the fleet.

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2.3 CPUE standardisations

CPUE analysis, based on procedures explained by Vignaux (1994) and modified by Francis (1999), uses Generalised Linear Models (GLM) to express the catch per unit effort (landed weight per stratum, i.e., unique trip, fishing day, method, statistical area, and target species in this analysis) as being dependent upon a set of explanatory variables in a multiplicative manner. The year effects extracted from the model were assumed to represent the fluctuations in relative abundance, having adjusted for effects of other factors such as vessels, months, and statistical areas.

The standardisation was carried out for the target pot fishery in Statistical Areas 049-052 by core vessels reporting on CELR forms as virtually all blue cod is caught from this combination of form type, method, statistical area, and target species (see Section 3.2 below).

We considered two models based on the GLM framework: a lognormal model fitted to all the non-zero strata and the Poisson-gamma model which assigns a positive probability to the zeros.

It is also a common practice for well determined target fisheries to fit a binomial model to zeros and combine the result with that of the lognormal model fitted to the positive catches (Vignaux 1994). This approach was not considered in this analysis given the low proportions of zeros and the lack of a trend (Table 6).

The lognormal model is a GLM with identity link function fitted to the log transformed catch (Yi). It models the mean as a linear function of the covariates and the variance as an unknown constant:

E(lg(Yi)) = Xj3

Var(lg(Yi)) = (Y

where X represents the covariates and (Y and j3 are the parameters to be estimated.

The Poisson-gamma model is a GLM with a log link function which models the log of expected catch as a linear function of the covariates and the variance as a nonlinear function of the mean. Supposew = E(Yi), the model states that:

In(,u;) = X j3

Var(Yi) = fjJ,u~ 1

where fjJ and j3 are the parameters to be estimated and B is a pre-chosen value. The Poisson-gamma distribution belongs to the Tweedie family (Dunn 2004) which includes a set of distributions depending onB (1< B< 2 for Poisson-gamma). The B can be selected through a profile likelihood maximization procedure (Smyth 1996). In this analysis B was set to be 1.40 which gave the best fit.

The candidate explanatory variables offered to the models were vessel, fishing year, and month. For the model fitted to all the areas combined, statistical area was included as a factor with four levels. The variables were selected in a stepwise fashion: the variable that resulted in the greatest improvement in R2 (also referred to as Percent of Deviance Explained, which is equal to 1 minus the ratio of the deviance of the model to the deviance of the null model) was included in each step. A stopping rule of 1 % change of R2 was used to produce a relatively parsimonious model with moderate explanatory power.

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3. RESULTS

3.1 Zero catches

The proportion of strata with zero catches varied between the target and bycatch fisheries in BCO 4. On average, less than 1 % of strata (i.e., a unique combination of trip, day, method, target species, and statistical area) per annum for the target fishery and over 50% of the bycatch fisheries recorded zero catches of blue cod (Table 6, Figure 4). The proportion of zero strata dropped in the early 1990s for the target fishery and in the late 1990s for the bycatch fishery. The decline seems to have coincided with the apparent shift from rock lobster targeted fishing towards blue cod targeted fishing. The proportion of strata for which blue cod were targeted increased from about 40% to 60%, whereas that of rock lobster target fishery decreased from around 50% to 20% in roughly the same period (Table 7, Figure 5). The annual reporting rate, measured as the ratio of estimated catches over landed weight was usually above 90% (Table 8, Figure 6). The reporting rate dropped from 1993-94 to 1995-96 and was lower in recent years compared with those in the early 1990s.

3.2 Distribution of annual landings

The cross tabulation of the total annual landings by form type, fishing method, target species, month, and statistical area are presented in Tables 9-13. The key points are summarised below.

Over 98% of the catches were reported on CELR forms, except that in 2004-05 about 5% were from the LCE forms (Figure 7). The LCE forms were introduced in 2004 and replace the CELR forms for catch and effort reporting by bottom longline vessels targeting bluenose or ling. Negligible catches were taken by vessels reporting on TCEPRs. Vessels operating in the target pot fishery in BCO 4 were usually small and less than 15 m in length.

Target pot fishing accounted for over 95% of annual blue cod landings, on average. Bycatch from rock lobster potting was insignificant and contributed consistently 1-2% annually through the years. The blue cod catches reported by bottom longliners accounted for up to 6% of total annual landings in 1996-97 and 2004-05, but were unstable and associated with large variability over the last 15 years (Figures 8 & 9).

There was a clear seasonal pattern in the fisheries (including target and bycatch components) and the landings peaked in the autumn-winter period from March to September (Figure 10). August and September outperformed other months and each, on average, accounted for over 15% of landings. Catches in March have been increasing steadily over the last 15 years. June seems to be a "rest" period in the busy season, with landings averaging below 10% of the total.

The main fishing grounds in BCO 4 were off the Chatham Islands in Statistical Areas 049-052, with less than 2% of blue cod catches taken outside these areas (Figure 11). The catches in 049 have been increasing both in quantity and in proportion. This area accounted for 40% to 50% of total catches in the region since the late 1990s. The annual landings from Statistical Area 051 were relatively stable, whereas those in 050 exhibited more variability. The landings in Statistical Area 052 also fluctuated, but on average this area contributed less than 10% of the total catches in BCO 4.

The proportion of the catch caught for bait (that is, recorded as "stored for bait" under type of destination on the catch and effort form) was less than 1 % each year. On average, over 96% of landed blue cod in BCO 4, including all fishing methods and target species, was in greenweight (GRE) state, and most of the remainder was gutted or headed-gutted (GUT or HGU state). However, the proportion of gutted blue cod increased in the last four years and varied between 5% and 7%. The introduction of LCE forms, on which all bycatch species catch is reported, may have played a part in this increase because about 40% of gutted catch were from trips using LCE forms in recent years.

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3.4 Influence from the rock lobster fishery

Statistical Areas 049-052 off the Chatham Islands are also important fishing grounds for rock lobster, which are mainly caught by rock lobster potting (RLP). The pattern of fishing effort and the seasonality of the rock lobster fishery may have affected these for blue cod because many vessels were involved in both fisheries. From 1989-90 to 2004-05 about 120 vessels targeted blue cod and 90 vessels targeted rock lobster in BCO 4; 83 vessels targeted both species. The timing of effort for the two fisheries was correlated to a certain extent with some overlap. The blue cod fishery generally operates in the late summer-winter season (February-September) (Figure 12). Before 1996-97, fishing effort in the rock lobster fishery was carried out in summer and autumn-winter months, but in recent years the main rock lobster fishing season has been during May-September (Figure 13).

3.5 Target blue cod pot fishery

Further analysis used only "core vessels", defined as those that operated in the target pot fishery for at least four years. The frequency distributions of the core vessels are shown in Figure 14. This effectively reduced the total number of vessels from 107 to 50, but retained 90% of the reported landings (Table 14). The consistent presence in time of the core vessels allowed the separation of the year effects from the vessel effects and the exclusion of the non-core vessels in the CPUE analysis effectively reduced the number of parameters in the model.

The effort record in the catch and effort data is the number of lifted pots (per day) for the pot target fishery. However, a large proportion of records in the catch-effort data recorded zero or missing values in this field. This proportion increased from year 1990-91 to 1996-97 and fluctuated around 50% after that (Figure 15). Since the catches were aggregated by unique combinations of day, statistical area, fishing method, and target species, the lack of a measure of the fishing effort within a stratum effectively reduces the explanatory power of the models in the subsequent CPUE analysis.

Percentage of strata with non-zero landings, average landings (kg) per stratum, total number of strata, and number of core vessels for each of the four Statistical Areas 049-052 are summarised in Table 15. In general, there was a negligible number of fishing days with reported zero catches for the target pot fishery, except in Statistical Area 049 in 1989-90, where the proportion was close to 50%. The average daily catches for each of the four statistical areas exhibited a similar trend and gradually increased over the past 15 years, fluctuating between 750 and 1500 kg (Table 15, Figure 16).

The catches by month aggregated from 1989-90 to 2004-05 for each of the Statistical Areas 049-052 showed a similar pattern, indicating the lack of a month*area interaction (Table 16, Figure 17). The seasonality within each of the statistical areas was in line with that of all the areas combined. There was very little fishing activity in summer from October to January and the catches climbed quickly and peaked in April, dropped in May and June, then rose again in July to September.

3.6 CPUE standardisations

CPUE indices for the each of the four Statistical Areas 049-052, as well as for all the statistical areas combined, were extracted from both models (Tables 17 & 18, Figure 18-29) and are presented in canonical form (Francis 1999), which normalised the back-transformed year effects by the mean of the indices. The variables selected into the models (Table 19), diagnostics (Figures 30-34), and predicted catch rates by other variables (Figures 35-39) were examined to assess the model fit.

The indices from the two models exhibited similar trends while the lognormal model tended to give larger standard errors. The diagnostics were the normal QQ plots. The residuals from the lognormal models deviated from normal distributions. The lognormal model also ignores the zero catch data. The quantiles of the normalised residuals from the Poisson-gamma models were closer to standard normal

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than those of lognormal models, indicating improvement of model fit, but problems in explaining the lower part of catches remained in most cases.

The lognormal models on average explained about 30% of the variance in the data and the Poissongamma models explained between 20% and 41 % (Table 19). Vessel and month entered all the models, indicating significant vessel effects and temporal variation of catches. Statistical area turned out to be insignificant in the models fitted to the data with all the four statistical areas combined, implying insignificant variations of catch rates among the four areas. The predicted catch rates by vessel and month (see Figures 35-39) show that some vessels clearly outperform the others and that catch rates are on average higher between March and September than the rest of the year in all four statistical areas, except that in Statistical Area 052 the seasonality of catch rates is less obvious.

The separate indices from models fitted to each of the areas exhibited various patterns but basically were similar to the combined indices (Figures 28 & 29). The standardised CPUE indices in general tracked the nominal CPUE (average catch per stratum) except that for the models fitted to the data in Statistical Area 052 the standardised index deviates from the nominal catch rate in 2004-05 (Figures 26 & 27). This discrepancy could be explained by the fact that in 2004-05 the fishery was dominated by vessel "8" which took more catch than the other two vessels (Table 15, Figure 39); therefore the jump of the nominal catch rate in 2004-05 was mainly a result of higher catches by that vessel.

4. CONCLUSIONS

Nearly all blue cod landed in BCO 4 is caught by small vessels targeting blue cod using cod pots off the Chatham Islands. The analysis suggests that the trends in relative biomass of BCO 4 are effectively monitored by the trends in CPUE based on target pot fishery.

The standardised CPUE indices in each of the Statistical Areas 049-052 have all increased in recent years and the current commercial catch levels from the main blue cod fisheries within BCO 4 appear to be sustainable, at least in the short term, based on the recent catch and effort data.

The trends of CPUE are similar among the four main statistical areas and the analysis indicates that statistical area does not fully represent the spatial variations of the catch rates within BCO 4 as it did not enter the models. The operations of the target pot fisheries in Statistical Areas 049-052 exhibited similar seasonality with a common autumn-winter peak. It is perhaps appropriate to monitor the trends in relative biomass of BCO 4 using the CPUE derived from all the areas combined. However, the monitoring of the fishery would be improved through the collection of catch and effort data on a finer spatial scale (Langley 2005).

The CELR forms systematically recorded missing or zero values in the field of effort number (number of pots lifted per day). The problem appears to be observed only in this analysis, not in analyses carried out in other fisheries such as BCO 3 and BCO 5 (Langley 2005). The source of errors is unclear and needs to be further examined. The CPUE analyses would be enhanced if accurate information on number of pot lifted was able to be incorporated into the models.

5. ACKNOWLEDGMENTS

This work was funded by the Ministry of Fisheries (Project BC02005/03). Thanks to Michael Beentjes for helpful comments on a draft of the manuscript.

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6. REFERENCES

Beentjes, M.P.; Carbines, G.D. (2003). Abundance of blue cod off Banks Peninsula in 2002. New Zealand Fisheries Assessment Report 2003116. 25 p.

Beentjes, M.P.; Carbines, G.D. (2005). Population structure and relative abundance of blue cod (Parapercis colias) off Banks Peninsula and in Dusky Sound, New Zealand. New Zealand Journal of Marine and Freshwater Research 39: 77-99.

Blackwell, R (1997). Abundance, size composition, and sex ratio of blue cod in the Marlborough Sounds, September 1996. New Zealand Fisheries Data Report 88. l7 p.

Blackwell, R (1998). Abundance, size and age composition, and yield-per-recruit of blue cod in the Marlborough Sounds, September 1995. N1WA Technical Report 30.47 p.

Carbines, G.D.; Beentjes, M.P. (2003). Relative abundance of blue cod in Dusky Sound in 2002. New Zealand Fisheries Assessment Report 2003137. 25 p.

Dunn, P. (2004). The Tweedie package. Dec 9, 2004. (R package available from http://cran.rproject.org/src/contrib/PACKAGES.htrnl)

Francis, RI.C.C. (1999). The impact of correlations in standardised CPUE indices. New Zealand Fisheries Assessment Research Document 99/42. 30 p. (Unpublished report held in NIW A library, Wellington. )

Langley, A.D. (2005). Summary of blue cod catch and effort data from the BCO 3 and BCO 5 fisheries, 1989-90 to 1999-2000. New Zealand Fisheries Assessment Report 2005130. 28 p.

Manning, MJ.; Hanchet, S.M.; Stevenson, M.L. (2004). A description and analysis of New Zealand's spiny dogfish (Squalus acanthias) fisheries and recommendations on appropriate methods to monitor the status of the stocks. New Zealand Fisheries Assessment Report 2004161. 135 p.

Ministry of Fisheries Science Group (Comp.) (2006). Report from the Fisheries Assessment Plenary, May 2006: stock assessments and yield estimates. 875 p. (Unpublished report held in NIW A library, Wellington.)

Smyth, G.K. (1996) Regression modeling of quantity data with exact zeros. Proceedings of the second Australia-Japan Workshop on Stochastic Models in Engineering, Technology and Management. Technology Management Centre, University of Queensland, 572-580.

Starr, PJ. (2003). Procedure for merging MFish landing and effort data. Version 1.0. 13 p. (Unpublished report available from the author: paul @starrfish.nen

Vignaux, M. (1994). Catch per unit effort (CPUE) analysis of west coast South Island and Cook Strait spawning hoki fisheries, 1987-93. New Zealand Fisheries Assessment Research Document 94111. 29 p. (Unpublished report held in NIW A library, Wellington.)

Warren, E.; Grindley, R; Carbines, G.; Teimey, L. (1997). Characterisation of the Southland blue cod fishery (1991-1996). Ministry of Fisheries, Wellington. 38 p. (Unpublished report held by Ministry of Fisheries, Dunedin)

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Table 1: Estimated catch, reported landings (t) and TACC of blue cod in BCO 4 from 1989-90 to 2004-05; year 1999 refers to fishing year 1998-99.

Year Estimated catch reported landings TACC 1990 302 317 749 1991 352 374 757 1992 349 361 757 1993 437 444 757 1994 516 520 757 1995 555 597 757 1996 433 503 757 1997 415 452 757 1998 554 588 757 1999 527 554 757 2000 486 512 757 2001 618 645 757 2002 617 645 759 2003 680 729 759 2004 673 706 759 2005 695 746 759

Table 2: The number of records in the catch and effort table containing NA values in the key fields. The trips with records containing NA values in any of those fields after imputation were deleted.

Raw data Groomed data

Vessel o o

Trip o o

Start date 10 4

Method 27 17

Target species 12 4

Statistical area 63

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Table 3: The number of records in the catch and effort table and the landing table at each stage of the compiling procedure.

Catch &effort Landing

Raw data 18003 10552

Groomed & unstratified data 17969 10 552

Stratified & allocated data 15036 10552

Table 4: The number of trips in the catch and effort table and the landing table at each stage of the compiling procedure.

Catch &effort Landing Matched trips

Raw data 9696 9701 9696

Groomed & unstratified data 9669 9701 9669

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Stratified & allocated data 9514 9701 9514

Table 5: Estimated catches and landings in BCO 4 fishing year for the groomed and unstratified data and the stratified and allocated data; the recovery rate is the estimated catch or landings in the stratified and allocated data as a percentage of that in the groomed and unstratified data; year 1999 refers to fishing year 1998-99.

Estimated catches Year Groomed & unstratified Stratified & allocated Recovery rate (%)

1990 302 302 100 1991 352 352 100 1992 349 349 100 1993 437 437 100 1994 517 517 100 1995 555 555 100 1996 430 430 100 1997 418 418 100 1998 553 553 100 1999 527 527 100 2000 486 486 100 2001 618 618 100 2002 617 617 100 2003 680 680 100 2004 673 673 100 2005 693 693 100

Landings Year Groomed & unstratified Stratified & allocated Recovery rate (%)

1990 317 310 97.8 1991 374 365 97.6 1992 361 351 97.2 1993 444 442 99.5 1994 520 517 99.4 1995 597 585 98.0 1996 503 483 96.3 1997 452 441 97.6 1998 588 577 98.1 1999 554 547 99.0 2000 512 503 98.2 2001 645 642 99.5 2002 645 642 99.5 2003 729 717 98.4 2004 706 697 98.7 2005 746 738 98.9

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Table 6: Proportion of strata with zero landed catch and the total number of strata in RCO 4 for target and bycatch fisheries of blue cod from 1989-90 to 2004-05; year 1999 refers to fishing year 1998-99.

Target Bycatch

Year Zero Total Zero Total 1990 10 431 92 406 1991 6 412 91 541 1992 4 365 96 468 1993 1 461 91 349 1994 0 582 90 362 1995 0 652 73 378 1996 1 494 67 370 1997 0 497 74 258 1998 526 56 389 1999 500 62 293 2000 497 52 460 2001 0 591 68 424 2002 0 508 35 423 2003 587 62 423 2004 0 570 58 355 2005 0 644 54 620 Total 8317 70 6519

Table 7: Number of strata by target species as a percentage of the total number of strata in RCO 4 from 1989-90 to 2004-05; year 1999 refers to fishing year 1998-99; RCO, blue cod; CRA, rock lobster.

Year BCO CRA Other Total 1990 51 41 8 837 1991 43 49 7 953 1992 44 52 5 833 1993 57 37 7 810 1994 62 29 10 944 1995 63 23 14 1030 1996 57 21 22 864 1997 66 17 17 755 1998 57 17 25 915 1999 63 20 17 793 2000 52 31 17 957 2001 58 24 17 1015 2002 55 16 30 931 2003 58 17 25 1010 2004 62 8 30 925 2005 51 8 41 1264 Total 56 25 19 14836

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Table 8: Estimated catches and landings (t) of blue cod in BCD 4 from 1989-90 to 2004-05; the reporting rate is the estimated catch as a percentage of the landings; year 1999 refers to fishing year 1998-99. Note: the figures differ slightly from those in previous tables as the fishing years used here are derived from the trip dates based on both landing and catch and effort data (therefore more accurate) whereas they are simply extracted from catch and effort data in previous tables.

Year Estimated catch Landing Reporting rate (%)

1990 302 310 98 1991 352 365 97 1992 349 351 99 1993 437 442 99 1994 517 509 102 1995 555 594 93 1996 430 482 89 1997 418 441 95 1998 553 577 96 1999 527 547 96 2000 486 503 96 2001 618 642 96 2002 617 642 96 2003 680 716 95 2004 673 684 98 2005 693 752 92

Table 9: Proportion (%) of annual landings (t) by form type in BCD 4 from 1989-90 to 2004-05; year 1999 refers to fishing year 1998-99.

Year CELR TCEPR LCE Other Total 1990 100 <1 <1 <1 310 1991 100 <1 <1 <1 365 1992 100 <1 <1 <1 351 1993 100 <1 <1 <1 442 1994 100 <1 <1 <1 509 1995 100 <1 <1 <1 594 1996 100 <1 <1 <1 482 1997 100 <1 <1 <1 441 1998 100 <1 <1 <1 577 1999 100 <1 <1 <1 547 2000 100 <1 <1 <1 503 2001 100 <1 <1 <1 642 2002 100 <1 <1 <1 642 2003 100 <1 <1 <1 716 2004 99 <1 1 <1 684 2005 95 <1 5 <1 752 Total 99 <1 1 <1 8557

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Table 10: Proportion (%) of annual landings (t) by fishing method in BCO 4 from 1989-90 to 2004-05; year 1999 refers to fishing year 1998-99; CP, cod pot; RLP, rock lobster pot; BLL, bottom long-lining.

Year CP RLP BLL Other Total 1990 97 2 <1 1 310 1991 97 2 1 <1 365 1992 97 2 <1 1 351 1993 99 <1 <1 442 1994 97 2 <1 509 1995 95 2 1 3 594 1996 91 2 5 2 482 1997 91 3 6 1 441 1998 95 1 3 <1 577 1999 96 2 1 547 2000 96 2 <1 503 2001 98 <1 642 2002 97 <1 2 642 2003 96 3 <1 716 2004 98 <1 2 <1 684 2005 92 1 6 <1 752 Total 96 2 1 8557

Table 11: Proportion (%) of annual landings (t) by target species in BCO 4 from 1989-90 to 2004-05; year 1999 refers to fishing year 1998-99; BCO, blue cod; CRA, rock lobster; HAP, hapuku; HPB, hapuku/bass, SCH, school shark.

Year BCO CRA HAP HPB SCH Other Total 1990 99 1 <1 <1 <1 <1 310 1991 99 1 <1 <1 <1 <1 365 1992 99 <1 <1 <1 <1 351 1993 99 <1 <1 <1 <1 442 1994 99 <1 <1 <1 1 <1 509 1995 97 1 <1 1 <1 <1 594 1996 94 1 <1 2 1 1 482 1997 97 <1 <1 1 441 1998 97 <1 <1 <1 577 1999 98 1 <1 <1 <1 <1 547 2000 98 <1 <1 <1 <1 503 2001 99 <1 <1 <1 <1 <1 642 2002 99 <1 <1 <1 <1 1 642 2003 97 1 1 1 <1 716 2004 99 <1 <1 <1 <1 684 2005 95 <1 1 <1 2 752 Total 98 1 <1 <1 8557

15

Table 12: Proportion (%) of annual landings (t) by month in BeO 4 from 1989-90 to 2004-05; year 1999 refers to fishing year 1998-99.

Year 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 Total

Oct <1 <1 <1

1 2 1 1

<1 <1

1 <1

1 <1

2 <1

4

Nov Dec <1 <1 <1 <1 <1 1 <1 <1 <1 <1 <1 1 <1 <1 <1 <1 <1

1 <1 <1 <1

1 1 1 <1

<1 1

3 1 <1

Jan Feb 1 2

<1 <1 <1 <1 <1 1 <1 <1 <1 2

1 2 1 6 3 4 3 13

4 3

<1 <1 1 2 6 1 2 3 1 3

Mar Apr May 11 6 8 7 9 8 2 9 13 8 28 13 6139

11 15 4

11 14 6 10 20 9 11 12 10 19 12 9 19 16 l7 17 l7 6 15 16 8 16 13 12 l7 21 10 11 12 13 13 15 10

Jun

8 4

17 5 8 2 5 6 4 7 5 6 7

11 7 7 7

Jul 25 23 31 l7 6

20 12 7 7

12 14 10 16 19 8

11 14

Aug 19 25 l7 11 21 17 24 25 24

7 13 25 18 18 13 15 18

Sep 20 22 10 16 34 25 22 15 25 16 12 14 19 5

17 18 18

Total 310 365 351 442 509 594 482 441 577 547 503 642 642 716 684 752

8557

Table 13: Proportion (%) of annual landings (t) by statistical area in BeO 4 from 1989-90 to 2004-05; year 1999 refers to fishing year 1998-99.

Year 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 Total

049 050 051 052 Other 28 19 50 2 <1 22 26 42 10 <1 44 18 35 3 <1 43 23 27 6 1 30 33 22 13 1 32 28 20 18 1 31 18 36 13 2 42 19 30 9 <1 34 32 22 11 1 51 21 20 7 <1 49 19 21 11 <1 43 24 25 9 <1 43 25 27 5 <1 45 19 23 13 <1 45 18 26 11 <1 38 19 28 13 2 40 23 27 10 1

Total

310 365 351 442 509 594 482 441 577 547 503 642 642 716 684 752

8557

16

Table 14: Proportion (%) of core vessel (2: 4 years in fishery) number and proportion (%) of landings by core vessels in BCO 4 (for cod pot, Statistical Areas 049-052) from 1989-90 to 2004-05; core vessels are those that have operated in the fishery for at least 4 years; year 1999 refers to fishing year 1998-99.

Year 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 Total

Non-core 34 31 24 25 20 27 20 11 14 11 4

o 8

22 12 32 52

Number

Core Total 66 35 69 32 76 29 75 32 80 40 73 80 89 86 89 96

100 92 78 88 68 48

41 40 38 29 27 26 22 26 32 32 37

107

Year 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 Total

Non-core 14 7

9 10 7

13 5 3 4

9 o o 5

10 9

20 8

Landings Core Total

86 302 93 354 91 341 90 434 93 491 87 564 95 437 97 402 96 549 91 522

100 483 100 628 95 622 90 686 91 671 80 687 92 8173

Table 15: Percentage of strata with non-zero landings (R), average landings (kg) per stratum (L), and total number of strata (S), number of core vessels (C) in each of the Statistical Areas 049-052 (cod pot) from 1989-90 to 2004-05; year 1999 refers to fishing year 1998-99.

Year 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005

R 54 82 92

100 100 100 100 100 100 100 100 100 100 100 100 100

049 L S C

540 89 4 648 99 4 819 176 9 931 201 9 683 205 13 926 169 11 800 154 10 811 201 16

1 001 190 12 1 216 205 12 1 048 219 12

967 275 10 1 287 187 12 1 130 234 11 1 282 222 14

979 207 11

R 100 100 100 100 100 100 100 100 99

100 99

100 100 100 100 100

050 L S C

565 48 4 1067 46 5 1547 24 4

971 84 6 995 162 7

1073 150 7 990 68 8 805 97 8

1251 136 6 1 261 56 6 1059 76 7 1366 112 6 1507 105 7 1423 75 5 1395 75 6 1 502 71 5

17

R 100 94

100 94 99

100 100 100 100 99 99

100 100 98

100 100

L 1084 1 127 1 100 1073 1 194

897 1493 1 133 1 196 1071 1057 1 129 1324 1311 1206 1409

051 S C

125 8 107 9 79 9 87 10 72 11 91 11 81 10 93 10 90 7 87 6 88 6

128 6 111 9 109 10 109 9 61 8

052 R L S C

100 888 4 100 1505 19 3 100 884 11 4 100 818 15 1 100 1257 32 4 100 988 53 7 100 1004 61 7 100 954 31 5 100 1 131 36 7 97 1039 32 3

100 940 47 4 100 983 57 3 100 1 227 15 2 100 1 110 40 4 100 1020 33 4 100 2772 13 3

Table 16: Percentage of catches (t) by months aggregated from 1989-90 to 2004-05 in each of the Statistical Areas 049, 050, 051, and 052 (for core vessels, cod pot).

049 050 051 052

Oct Nov Dec 110 100 000 000

Jan Feb Mar Apr May Jun 2 5 14 18 8 5 1 3 16 15 11 8 o 0 10 11 10 9 o 0 12 20 11 4

Jul Aug Sep Total 10 17 17 2954 15 14 14 1613 19 22 18 1776 14 16 22 544

Table 17: CPUE indices and the corresponding lower/upper bound from lognormal and Poisson-gamma models fitted to RCO 4 data (for core vessels, cod pot, Statistical Areas 049-052 combined) from 1989-90 to 2004-05; year 1999 refers to fishing year 1989-99.

Year 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005

Index 0.79 0.83 0.77 0.78 0.82 0.93 0.96 0.82 0.96 1.22 1.04 1.13 1.36 1.35 1.28 1.33

Lognormal

Lower Upper 0.71 0.87 0.75 0.69 0.71 0.76 0.87 0.88 0.76 0.89 1.12 0.97 1.05 1.25 1.25 1.19 1.22

0.90 0.84 0.84 0.89 1.01 1.05 0.89 1.04 1.32 1.13 1.21 1.47 1.45 1.38 1.44

Year 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005

Index 0.86 0.95 0.94 0.92 0.90 0.93 0.92 0.84 0.92 1.10 0.99 1.02 1.23 1.21 1.20 1.18

Poisson-gamma

Lower Upper 0.80 0.93 0.89 0.88 0.86 0.85 0.88 0.87 0.79 0.87 1.04 0.94 0.97 1.16 1.15 1.14 1.11

1.02 1.01 0.98 0.96 0.99 0.98 0.90 0.98 1.17 1.05 1.07 1.30 1.27 1.27 1.25

Table 18: CPUE indices from lognormal and Poisson-gamma models fitted to data in each of the Statistical Areas 049, 050, 051 and 052 (for core vessels, cod pot) from 1989-90 to 2004-05; year 1999 refers to fishing year 1989-99.

Year

1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005

049

1.05 0.78 0.68 0.61 0.69 1.05 0.96 0.78 0.99 1.30 1.17 1.21 1.46 1.30 1.19 1.30

050 0.71 0.86 0.69 0.82 0.83 0.90 0.85 0.82 0.92 1.15 1.08 1.20 1.39 1.37 1.49 1.41

Lognormal 051 052

0.73 1.14 0.82 1.46 0.82 0.65 0.96 1.11 0.75 1.14 0.97 1.05 1.10 0.91 1.01 1.26 1.24 1.18 1.17

0.73 0.89 0.97 0.79 0.90 0.94 1.11 0.88 0.91 1.24 1.23 1.36 1.17

18

049 0.82 0.91 0.83 0.84 0.78 1.06 0.88 0.85 0.97 1.25 1.09 1.08 1.32 1.17 1.21 1.18

050 0.70 0.96 1.44 0.86 0.86 0.87 0.79 0.75 0.94 1.00 0.97 1.12 1.24 1.26 1.36 1.25

Poisson-gamma

051 052 0.79 1.14 0.84 1.27 0.96 0.86 0.99 1.17 0.78 1.24 0.96 1.07 1.02 0.91 0.96 1.15 1.14 1.07 1.09

0.99 0.92 0.97 0.78 0.83 0.84 1.00 0.88 0.92 1.19 1.19 1.19 1.23

Table 19: Variables included in order of importance in the stepwise regression of lognormal and Poisson-gamma models fitted to data in each of the Statistical Areas 049, 050, 051 and 052, as well as all the areas combined (for core vessels, cod pot); R2 refers to the percent of deviance explained.

Lognormal Poisson-gamma Variable R2 Variable R2

BC04 fishing year 0.046 fishing year 0.027 vessel 0.200 vessel 0.209 month 0.300 month 0.251

049 fishing year 0.080 fishing year 0.048 month 0.220 vessel 0.207 vessel 0.296 month 0.287

050 fishing year 0.110 fishing year 0.100 vessel 0.260 vessel 0.276 month 0.308 month 0.302



19

SCO 10

,L3SC04

I

•

Figure 1: The Quota Management Areas for blue cod.

20

405 \ 401 402 403 404 406

049 _ 050 &J, ~

d (~

-it 052 - 051

407 408 409 410 412

) 411

Figure 2: General Statistical Areas in BCO 4: 049-052 are located off the Chatham Islands and correspond to rock lobster Statistical Areas 940-943.

'" 0> C

'0 c j

1500

1000

500

5001000

5001000 5001000

5001000

5001000

Estimated catch

5001000

5001000

5001000

1500

1000

500

Figure 3: Daily landings vs. estimated catches (kg) for the groomed and stratified data. The x and y axis have a 1:1 ratio.

21

c: 0 t: 0 0-e a..

o o

0 CO

0 <0

0 "<t

0 C\I

\ , \

-- Target -1::.-- Bycatch

, ----- --------- ----------- ----- -----------------lLS ---------- ---- -ts -- ---- ---- -------- ------------- --------- ------ -------- --- -------- ----------

, ~ \ "6~/ \ 6

\ ' \ , t:,. / , t:,.~

\ .... .",..... / \ - ... 6. 6~ ',/ '. " ~~'6

6 , I -------- .......... . .......... --........ . .. -.......... ......................... -.. ...... .. --. . _--.-_ . __ .... .. ,---····7····· ····- -······ ··- -··--- -\ I \ I , I • I

6

0 __

0-0_ o 0-0_0-0_0-0-0-0_0_0-0_0_0

90 91 92 93 94 95 96 97 98 99 00 01 02 03 04 05

Fishing year

Figure 4: The proportion of strata with zero landed catch in BCO 4 from 1989-90 to 2004-05 for target and bycatch fisheries of blue cod; year 99 refers to fishing year 1998-99.

0 0 0r-

-- BCO -1::.-- CRA

o CX)

--+-- Other

o c: 0 0 <0 t: 0 0-0 .... 0 a.. "<t

~o_o, / , /0, 0 o~o, o 0 0 , / -0- "

---Q~tr--~~~~--------- - ----- - -------------------------- ----~ - -- - -------- - ------------------g-- -6~~ 0_0 \\ +

6 , ,

0 C\I

, 6 ' '6 / ' +-_ -+'

-------- ----- - - - ---------------':.:::,~lS---------- - ------,+.-------r~-----~-..... ts.--,-'-:.---:::+::::------------~~:2fr'-.. -,,- -"- t;/ ,Y,

_--+/ '4-'---t:,.--~+---- - +- ----+ '6---6" +-' , + --, __ + _____ + ___ -- + ---" 6 - --I:.

o

90 91 92 93 94 95 96 97 98 99 00 01 02 03 04 05

Fishing year

Figure 5: The number of strata by target species expressed as a percentage of the total number of strata; year 99 refers to fishing year 1998-99; BCO, blue cod; CRA, rock lobster.

22

Q) -ro ..... O'l c :e 0 0.. Q)

a:::

o 0-~

g-

R-

g-

g-

o_o/~\ 0

0_0/ / 0_0-0-0-0 / "'" 0-- --0

0"", / 0 o

I I I I I I I I I I I I I I I I

90 91 92 93 94 95 96 97 98 99 00 01 02 03 04 05

Fishing year

Figure 6: Reporting rates in BCO 4 from 1989-90 to 2004-05; the reporting rate is the estimated catches expressed as a percentage of landings; year 99 refers to fIShing year 1998-99 •

.;:t 0

o

C\J 0

0 ..... 0 ro Q) >. ex> O'l 0) c :E

CD en u::: 0)

.;:t 0)

C\J 0)

0 0)

CEl TCP lCE Other

Form types

Figure 7 : Annual landings (t) by form type in BCO 4 from 1989-90 to 2004-05; the bubble area is proportional to the catch; the largest circle represents 715 t ; year 99 refers to fishing year 1998-99; CEL, CELR; TCP, TCEPR.

23

""'" 0

C\J 0

0 ..... 0 ct1 Q) >. CO C> (J) c ..c

<.0 (J)

u:::: (J)

""'" (J)

C\J (J)

0 (J)

o

o

o

o o o o

o

o

BLL CP

o o

o

o

o o

o

o o

o

o

o o

o o o

o

o o

o

o

RLP Other

Primary method

Figure 8: Annual landings (t) by fishing method that caught most blue cod in BCO 4 from 1989-90 to 2004-05; the bubble area is proportional to the catch; the largest circle represents 691 t ; year 99 refers to fishing year 1998-99; BLL, bottom long-lining; CPo cod pot; RLP, rock lobster pot.

0 0 0

""'" 0 0

o 0 0 0

C\J 0

0

o 0

0 ..... 0

o

ct1 Q) 0 o

>. co C> (J)

0 0

c 0 0 0

..c <.0 (J)

u:::: (J) 0 0 0 o

o 0 0

""'" (J) 0

o

C\J (J)

o

0 (J)

o

BCO CRA HAP HPB SCH Other

Target species

Figure 9: Annual landings (t) by target species that caught most blue cod in BCO 4 from 1989-90 to 2004-05; the bubble area is proportional to the catch; the largest circle represents 715 t ; year 99 refers to fishing year 1998-99; BCO, blue cod; CRA, rock lobster; HAP, hapuku; HPB, hapukulbass; SCH, school shark.

24

@ • ..q-0 •

@ -0 <iD • C\J 0 0

0 0 0

@ @ €) • 0 0 ..... 0 0 @ <U @ Q) 0 • >. ex:> 0 O'l 0> 0

c 0

..c (0 (j) @

u::: 0>

0 @ @ @ ED

@ @ 0

..q- ED 0> 0 0 0

0 <iD C\J 0 0> 0

0

0 0>

Oct N@v Dec Jan Feb Mar Apr May Jun Jul Aug Sep

M@nth

Figure 10: Annual landings (t) by month in BCO 4 from 1989-90 to 2004-05; the bubble area is proportional to the catch; the largest circle represents 160 t; year 99 refers to fishing year 1998-99 .

..q-0

C\J 0

0 ..... 0 <U Q) >. ex:> O'l 0> C E

(0 (j)

u::: 0>

..q-0>

C\J 0>

0 0>

049 050 051

Statistical area

€)

€)

052

o

o

o

<iD @

@

o

Other

Figure 11: Annual landings (t) by statistical areas in BCO 4 from 1989-90 to 2004-05; the bubble area is proportional to the catch; the largest circle represents 322 t; year 99 refers to fishing year 1998-99.

25

Sep

Aug

Jul

Jun

May ..c Apr -c 0 ~ Mar

Feb

Jan

Dec

Nov

Oct

90 91 92 93 94 95 96 97 98 99 00 01 02 03 04 05

Fishing year

Figure 12: Density plot of number of fishing days per month for blue cod target fIShery in BCO 4 from year 1989-90 to 2004-05; year 99 refers to fishing year 1998-99.

Sep

Aug

Jul

Jun

May ..c Apr -c 0 ~ Mar

Feb

Jan

Dec

Nov

Oct

90 91 92 93 94 95 96 97 98 99 00 01 02 03 04 05

Fishing year

Figure 13: Density plot of number of fishing days per month for rock lobster target fishery in BCO 4 from year 1989-90 to 2004-05; year 99 refers to fishing year 1998-99.

26

50 49 48 47 46 45 44 43 42 41 40 39 38 37 36 35 34 33 32 31 30 29

>- 28 ~ 27

26 25 24 23

Q) C/) C/) Q)

> 22 21 20 19 18 17 16 15 14 13 12 11 10

9 8 7 6 5 4 3 2 1

. . · ..

:::::::::::1:::::::::::::r::::::::::.·~.q.'.·.I .... ·.~.·.··::·f~Q.··.·.··.··.····:::,:.· •. · •. i.·· .. ·.:·:: • • ":,"', .• :..'" _.J ":: ',

o + 0 + 0 : 0 , ····0······4-······-Q-······~····· · -Q-···· · .

o c; 0 c; 0

.. (1) .....•..... * ....•...•.. o + 0 ~ 0 •

····0······ <?- ...... -Q- ...... <?- ...... -Q- ..... ·0······

.... : ...... i ...... : ...... i ...... : .... ,. o 0 Q

•• -E) •••••• ~ •••••• ® ... <I> ~ 0

.--e-----.--.. -~--o c; 0

90 91 92 93 94 95 96 97 98 99 00 01 02 03 04 05

Fishing year

Figure 14: The number of fishing days by each of the core vessels (operated in the fisheries for at least four years) for the target pot fishery from 1989-90 to 2004-05; bubble area is proportional to number of tows; the largest circle represents 83 days/yr; vessels keys are arbitrary numbers; year 99 denotes the 1998-99 fishing year.

27

c 0 t 0 c.. e a..

o 0-

g-

~-

~-

~-

0-

o

o 0 /

--\-------------- -----------~--~-~JL~~~2-~o-~~-~-o~----_0 0_0 0

0-

0/

------~~-------------------------------------------------------------

I I I I I I I I I I I I I I I I

90 91 92 93 94 95 96 97 98 99 00 01 02 03 04 05

Fishing year

Figure 15: Number of strata with missing or zero effort number (pot lifts) as a percentage of total number of strata in BeO 4 (cod pot target fishery in Statistical Areas 049-052) from 1989-90 to 2004-05; year 99 refers to fishing year 1998-99.

0 0 0 ('t')

0 0 to C\J

0 0

.--. 0 0) C\J

~ 0 en

Q) 0 .c to .8 CIl () 0

0 0 T""

0 0 to

0

-- 049 -l::r- 050

x ; ! , .+ .. 051

'~,--es-2- -----f---, ! I

I ;

/::;. i ----~-~--------------~-------------------~~~A----~~~-

'\ /" ,', A" -L..lo---t::..r + I / ' , LJo .!r ... + ,.' /). , x :' ", ~--- {;r ,' ... ,,<,-" "7 Q,/

, I ' \ __ I'"t", / .. _e_ - ~ .... ~ / ~ ~:;.o ..... :~ ",,- -tt + ,t.,· .J.,. ... ~< + .... ~t ... ' ',', A , + to :"/' ~ ~ ... ' •••• +/~ ~ . ,'" £::i. \ I - a. L.l.... .,.., ;,;-r.;., x _._e_ ... /; -...." l / '~,......;::X7'--.6~~"~':.::!~-<}/0 ·-·-X~~ x 0 --7---~-----~-~---------------------------------------/ 0 0

~-

90 91 92 93 94 95 96 97 98 99 00 01 02 03 04 05

Fishing year

Figure 16: The average landings (kg) per stratum for Statistical Areas 049-052 respectively (core vessels, cod pot target fishery) from 1989-90 to 2004-05; year 99 refers to fishing year 1998-99.

28

0 0 CO

0 0 If)

0 0 "<t

S en Q) 0 .r::: 0 B ('I)

~ ()

0 0 C\I

0 0 0r-

O

o ~ 049 -b-- 050 .+ .. 051 0_0

--------------------------~-- ------- .~-~~~~ o

---------~~--------~--b.- ___ b. ~ ... 6

I ',0 :' . ---- 6---- b. I .... ' I

I + - " / : + ........ ·······:4~.;. ..... .: / --------------------~--~~~------------~ ~---------------

/ I: '-A/

I :' L.> ._ X , " .... X...... ... .....

I -' ... ,.... ........ X .---.- X· o i ,/ ",.X· .... X..... . ..... "

0_ / 6-~-~ :./ -·-X .... ~ =--.. - ~=== .a. ... -~::.:. *.-.~ * ....

Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep

Month

Figure 17: Catches (t) by months aggregated from 1989-90 to 2004-05 for each of the Statistical Areas 049, 050, 051 and 052 (for core vessels, cod pot); year 99 refers to fishing year 1998-99.

29

W ::J q a.. ()

o o

90 91 92 93 94 95 96 97 98 99 00 01 02 03 04 05

Fishing year

Figure 18: Standardised CPUE indices from the lognormal model fitted to BCO 4 data (for core vessels, cod pot, Statistical Areas 049-052). Dotted line represents the raw CPUE indices (average catches per stratum standardised to the mean) and vertical bars are the 95% confidence intervals; year 99 refers to fishing year 1998-99.

W

q C\I

::J q a.. ()

q o

90 91 92 93 94 95 96 97 98 99 00 01 02 03 04 05

Fishing year

Figure 19: Standardised CPUE indices from the Poisson-gamma model fitted to BCO 4 data (for core vessels, cod pot, Statistical Areas 049-052). Dotted line represents the raw CPUE indices (average catches per stratum standardised to the mean) and vertical bars are the 95 % confidence intervals; year 99 refers to fishing year 1998-99.

30

LU ::::)

a.. ()

q C\J

t.q ,...

q ,...

L{)

0

o o

-~ ., -~ ~, .. ' ----- - -- :-:-:.,.,-...:'- ----- --- -- - - - - '.:. -- --

90 91 92 93 94 95 96 97 98 99 00 01 02 03 04 05

Fishing year

Figure 20: Standardised CPUE indices from the lognormal model fitted to data in Statistical Area 049 (for core vessels, cod pot). Dotted line represents the raw CPUE indices (average catches per stratum standardised to the mean) and vertical bars are the 95 % confidence intervals; year 99 refers to fishing year 1998-99.

w

q C\J

::::) q a.. ()

t.q o

o o

90 91 92 93 94 95 96 97 98 99 00 01 02 03 04 05

Fishing year

Figure 21: Standardised CPUE indices from the Poisson-gamma model fitted to data in Statistical Area 049 (for core vessels, cod pot). Dotted line represents the raw CPUE indices (average catches per stratum standardised to the mean) and vertical bars are the 95% confidence intervals; year 99 refers to fishing year 1998-99.

31

W ::J a.. o

q C\J

q

q o

" , . , . . . . . , . , . , . , . . . . . -------- ------~-------------, . . .

,,'

-~----------------------. ,

90 91 92 93 94 95 96 97 98 99 00 01 02 03 04 05

Fishing year


W ::J a.. 0

q C\J

t.q

q

t.q 0

q o

", ",

90 91 92 93 94 95 96 97 98 99 00 01 02 03 04 05

Fishing year

Figure 23: Standardised CPUE indices from the Poisson-gamma model fitted to data in Statistical Area 050 (for core vessels, cod pot). Dotted line represents the raw CPUE indices (average catches per stratum standardised to the mean) and vertical bars are the 95 % confidence intervals; year 99 refers to fishing year 1998-99.

32

w ~ a.. ()

q C\J

LC'l ..-

q ..-

LC'l 0

q o

' ..

90 91 92 93 94 95 96 97 98 99 00 01 02 03 04 05

Fishing year


W ::::)

a.. ()

q C\J

LC'l ..-

q

LC'l 0

o o

90 91 92 93 94 95 96 97 98 99 00 01 02 03 04 05

Fishing year


33

w ::> a.. o

q (\J

tq o

q o

:.. .. :...- ----,---" -

--'at'

90 91 92 93 94 95 96 97 98 99 00 01 02 03 04 05

Fishing year


w

q (\J

::> q a.. o

tq o

q o

90 91 92 93 94 95 96 97 98 99 00 01 02 03 04 05

Fishing year


34

>< Q) "0 C

q C\J

q ,....

Lq o

o o

~ BC04 -~- 049 .. +-. 050 .-x-. 051 ~- 052

90 91 92 93 94 95 96 97 98 99 00 01 02 03 04 05

Fishing year

Figure 28: Standardised CPUE indices from the lognormal model fitted to data in each of the Statistical Areas 049, 050, 051 and 052, as well as all the areas combined (for core vessels, cod pot); year 99 refers to fishing year 1998-99.

>< Q) "0 C

q C\J

Lq ,....

q

Lq 0

q o

90 91 92 93 94 95 96 97 98 99 00 01 02 03 04 05

Fishing year

Figure 29: Standardised CPUE indices from the Poisson-gamma model fitted to data in each of the Statistical Areas 049, 050, 051 and 052, as well as all the areas combined (for core vessels, cod pot); year 99 refers to fishing year 1998-99.

35

• .. .. /.,

('I")

(IJ C)

(IJ

:::::I :::::I N "0 "0 til til Q) Q) '- "---

"0 N "0 Q) I Q)

N N '6 '6 '- '- C) (IJ (IJ

"0 "<;j "0 c: I c: (IJ (IJ ...... ...... ,,-(j) (j) I •

(D I

N I

ro .. I ('I")

I

-4 -2 0 2 4 -4 -2 0 2 4

Quantiles of the standard normal distribution Quantiles of the standard normal distribution

Figure 30: Plots of normalised residuals against standard normal quantiles from the lognormal (left) and Tweedie (right) models fitted to BeO 4 data (for core vessels, cod pot, Statistical Areas 049-052 combined).

C)

N I

.I "<;j --I

(D I

-3 -2 -1 0 1 2 3

Quantiles of the standard normal distribution

(IJ :::::I "0 til Q) "---

C)

,,I

N I

<:'0 I

-3 -2 -1 0 2 3


Figure 31: Plots of normalised residuals against standard normal quantiles from the lognormal (left) and Tweedie (right) models fitted to data in Statistical Area 049 (for core vessels, cod pot).

36

eu ::::l -0 (f) (J) L-

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37

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Figure 35: Expected catch rates (kg per stratum) as a function of each covariate, for median values of the other covariates from the lognormal (up) and Poisson-gamma (down) models fitted to BeO 4 data (for core vessels, cod pot, Statistical Areas 049-052 combined); vessel keys are arbitrary numbers.

38

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Figure 36: Expected catch rates (kg per stratum) as a function of each covariate, for median values of the other covariates from the lognormal (up) and Poisson-gamma (down) models fitted to data in Statistical Area 049 (for core vessels, cod pot); vessel keys are arbitrary numbers.

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Figure 37: Expected catch rates (kg per stratum) as a function of each covariate, for median values of the other covariates from the lognormal (up) and Poisson-gamma (down) models fitted to data in Statistical Area 050 (for core vessels, cod pot); vessel keys are arbitrary numbers.

39

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Figure 38: Expected catch rates (kg per stratum) as a function of each covariate, for median values of the other covariates from the lognormal (up) and Poisson-gamma (down) model fitted to fitted to data in Statistical Area 051 (for core vessels, cod pot); vessel keys are arbitrary numbers.

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40

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Summary of the blue cod (Parapercis colias) catch and ...docs.niwa.co.nz/library/public/FAR2006-61.pdf · difference caused by various form types (e.g., TCEPR forms record tow by