CONSULTANCY AND RESEARCH IN AQUACULTURE AND THE AQUATIC ENVIRONMENT

A Company in the NIVA-group

Mitigating the environmental impacts of aquaculture

Acceptable impact?

For impacts to be acceptable, the impact must be reversible or the ecosystem can recover.

Impact to sediments, impact of nutrients in water column

AZE – acceptable zones of environmental impact – local to the farm or licensed area

Zoning of aquaculture so that impact is confined to certain zones

Permanent impacts must be considered very carefully with a full risk analysis undertaken.

Introduction of exotic species, cutting mangroves for ponds, draining wetlands

Precautionary approach

Recovery

Little is known about the rates of recovery of aquaculture sites, and most of what is known is from a small number of studies of abandoned sites.

More is known about short term recovery - fallowing

Oxygen dynamics play a major role in site recovery. Without adequate oxygen some of these processes cannot occur.

Many other factors, including physical conditions related to currents and mixing, can affect recovery.

Environmental management of aquaculture

Mitigating environmental problems requires concerted action of all farms in the water body.

There is pressure to reduce environmental impacts of aquaculture due to increased utilisation of aquatic resources, consumers, governments and the international community

Improvements in environmental sustainability of marine fish farming have been the made by use of – fallowing, – improved cage design to minimize escapees– reduced usage of antibiotics.

Environmental management of aquaculture

There is more effective enforcement of regulations throughout the world, although these measures are targeted at the farm level.

Regulations appear to be strong in those countries where the growth of aquaculture has been most rapid and producing high-value commodities.

In many countries, the industry has taken the lead to respond to the environmental pressures, mostly driven by market forces.

Producer organisations - Codes of Conduct, best practice, etc.

Wallmart – GAA – sustainable sources

Mitigation of impact

As a general rule, inputs should be minimized or more efficiently used where possible.

Mitigation of aquaculture impacts can take a variety of forms.

Improved feed quality Improved feeding strategy Fallowing Distance between farms Zoning Extractive species Integrated aquaculture

Fallowing

Fallowing is the removal or cages from an area after production to allow the sediments to recover before starting production again

It has been shown in Norway to reduce outbreaks of disease

It allows sediments to become repopulated. Recovery rate of sediments is dependent on

– Temperature– Oxygen– Currents– Level of impact

Improved feed conversion rate

Feed is the greatest input to fish farming. If you can reduce feed input you will reduce waste output and environmental impact

Automated feeding especially with feedback systems have significantly reduced feed inputs whilst maintaining productivity.

In salmon farming feed conversion ratio have been reduced from 1.5 to near 1.1. Such reduction reduceds organic matter and nutrients discharged to the environment.

However, other types of aquaculture (sea bream and sea bass in the Mediterranean Sea) have FCRs close to 2:1 and still need to improve their feed conversion ratios.

Improved digestibility of feed

Dry Feed Addition of a higher percentage of digestible proteins Extruded feed vs pelleted feed

Feed Type Moisture (%)

FCR

Wet to wet

FCR

Dry to wet

Trash fish - 85 12:1 1.8:1

Moist - 30 3:1 2.1:1

Dry - 10

Dry (Norway) - 10

2:1

1.1:1

1.8:1

1:1

Improved feeding strategy – quantity of feed

Timing feeds per day Quantity per feed

Quantity of feed is affected by– Size of fish– Water temperature– Growth rate

Improved feeding strategy - timingOxygen levels inside a fish pen

0

1

2

3

4

5

6

8:00 10:00 12:00 14:00 16:00 18:00 20:00 22:00 0:00 2:00 4:00 6:00 8:00

Time

mg

O2

Feeding

Feeding timing

In the Mediterranean, until we studied feeding behaviour of Mediterranean seabass we did not realise that during winter they preferred to feed at night

Fish feeding is affected by – cloudy days– Lightening– Time of day - early morning, early evening– Birds in area– Predator fish beneath cages– etc,

Seabream - Specific growth rate

SPECIFIC GROWTH RATE (SGR)

Temp mean weight (gr.)min 35 48 60 80 100 150 200 250 300 350 400 450 500

max 48 60 80 100 150 200 250 300 350 400 450 500 600

12 14 0.19 0.15 0.12 0.11 0.10 0.07 0.07 0.06 0.05 0.05 0.05 0.05 0.0414 16 0.43 0.34 0.26 0.24 0.22 0.17 0.15 0.14 0.12 0.10 0.09 0.09 0.0816 18 0.75 0.59 0.46 0.42 0.38 0.31 0.27 0.24 0.21 0.17 0.16 0.14 0.1218 20 1.28 1.03 0.81 0.74 0.65 0.52 0.46 0.41 0.36 0.30 0.27 0.24 0.2020 22 1.92 1.59 1.27 1.15 0.99 0.78 0.70 0.62 0.54 0.45 0.40 0.36 0.3022 24 2.43 2.04 1.66 1.49 1.26 1.00 0.89 0.79 0.69 0.57 0.51 0.46 0.4024 26 3.02 2.54 2.06 1.85 1.57 1.24 1.10 0.99 0.86 0.71 0.64 0.57 0.5026 27 3.25 2.74 2.22 1.99 1.69 1.34 1.19 1.06 0.92 0.77 0.69 0.61 0.5327 28 3.30 2.78 2.25 2.02 1.72 1.36 1.21 1.08 0.94 0.78 0.70 0.62 0.5428 29 2.60 2.19 1.78 1.59 1.35 1.07 0.95 0.85 0.74 0.62 0.55 0.49 0.4229 30 1.95 1.64 1.33 1.20 1.02 0.80 0.71 0.64 0.55 0.46 0.41 0.37 0.32

Optimal temperature for growth is 28 'C

Optimal feeding rates

DAILY FEEDING RATE (SFR)Temp mean weight (gr.)

min 35 48 60 80 100 150 200 250 300 350 400 450 500 max 48 60 80 100 150 200 250 300 350 400 450 500 600

12 14 0.8 0.6 0.5 0.5 0.5 0.4 0.4 0.4 0.3 0.3 0.3 0.3 0.314 16 0.9 0.7 0.6 0.6 0.6 0.5 0.5 0.5 0.4 0.4 0.4 0.3 0.316 18 1.3 1.0 0.8 0.8 0.8 0.7 0.7 0.6 0.6 0.5 0.5 0.4 0.418 20 1.9 1.6 1.3 1.2 1.2 1.1 1.0 0.9 0.9 0.8 0.7 0.6 0.620 22 2.4 2.0 1.7 1.6 1.5 1.4 1.3 1.2 1.1 1.0 0.9 0.8 0.722 24 2.9 2.4 2.1 2.0 1.8 1.6 1.5 1.4 1.3 1.2 1.1 1.0 0.924 26 3.6 3.1 2.6 2.5 2.3 2.0 1.9 1.8 1.6 1.5 1.4 1.2 1.126 27 4.1 3.5 3.0 2.8 2.6 2.3 2.2 2.0 1.9 1.7 1.5 1.4 1.327 28 4.3 3.7 3.2 3.0 2.7 2.5 2.3 2.2 2.0 1.8 1.6 1.5 1.428 29 3.6 3.1 2.7 2.5 2.3 2.1 1.9 1.8 1.7 1.5 1.4 1.3 1.129 30 2.8 2.4 2.1 2.0 1.8 1.6 1.5 1.4 1.3 1.2 1.1 1.0 0.9

optimal temperature for food consumption is 28 'C

Optimal feed conversion rate

FEED CONVERSION RATE (FCR)Temp mean weight (gr.)

min 35 48 60 80 100 150 200 250 300 350 400 450 500 max 48 60 80 100 150 200 250 300 350 400 450 500 600

12 14 4.00 4.07 4.31 4.56 4.87 5.54 5.85 6.13 6.47 6.93 7.15 7.36 7.7014 16 2.15 2.18 2.31 2.44 2.61 2.97 3.13 3.28 3.47 3.71 3.83 3.94 4.1216 18 1.72 1.74 1.85 1.95 2.09 2.38 2.51 2.63 2.77 2.97 3.06 3.15 3.3018 20 1.49 1.51 1.60 1.69 1.81 2.06 2.17 2.28 2.40 2.57 2.65 2.73 2.8620 22 1.25 1.27 1.34 1.42 1.52 1.73 1.82 1.91 2.01 2.16 2.23 2.29 2.4022 24 1.18 1.20 1.27 1.34 1.43 1.63 1.72 1.80 1.90 2.04 2.10 2.17 2.2724 26 1.19 1.21 1.28 1.35 1.45 1.65 1.74 1.82 1.92 2.06 2.12 2.19 2.2926 27 1.25 1.27 1.34 1.42 1.52 1.73 1.82 1.91 2.01 2.16 2.23 2.29 2.4027 28 1.32 1.34 1.42 1.50 1.60 1.82 1.92 2.01 2.13 2.28 2.35 2.42 2.5328 29 1.40 1.42 1.50 1.59 1.70 1.93 2.04 2.14 2.25 2.42 2.49 2.57 2.6829 30 1.45 1.48 1.56 1.65 1.77 2.01 2.12 2.22 2.35 2.51 2.59 2.67 2.79

optimal temp for Food conversion rate is 24 'C

Optimal number of pellets per day

NUMBER PELLETS PER DAY AND FISH

feed Mistral21 Mistral21 Mistral21 Mistral21 Mistral21 Mistral21 Mistral21 Mistral21 Mistral21 Mistral21 Mistral21 Mistral21 Mistral21size 3 3 3 3 5 5 5 5 5 5 5 5 7pellets / kg 21250 21250 21250 21250 7520 7520 7520 7520 7520 7520 7520 7520 3150

Temp mean weight (gr.)min 35 48 60 80 100 150 200 250 300 350 400 450 500

max 48 60 80 100 150 200 250 300 350 400 450 500 <

12 14 6.8 7.1 7.5 9.4 4.5 5.4 6.5 7.9 8.5 9.4 10.7 12.0 5.114 16 8.2 8.6 9.1 11.4 5.4 6.8 8.2 9.5 10.3 10.7 11.5 12.0 5.316 18 11.4 11.8 12.5 15.7 7.5 9.6 11.5 13.2 14.2 14.6 15.2 15.5 6.818 20 16.8 17.8 19.2 23.8 11.1 14.1 17.0 19.5 21.0 21.6 22.6 23.0 9.320 22 21.1 23.1 25.5 31.2 14.1 17.8 21.5 24.6 26.6 27.4 28.7 29.2 11.922 24 25.2 28.1 31.3 38.2 17.0 21.5 25.9 29.6 32.0 33.0 34.6 35.3 14.924 26 31.7 35.2 39.3 47.9 21.4 27.0 32.5 37.2 40.2 41.4 43.5 44.3 18.826 27 35.8 39.8 44.4 54.1 24.1 30.4 36.7 41.9 45.3 46.8 49.1 50.0 21.127 28 38.3 42.6 47.5 57.9 25.8 32.6 39.3 44.9 48.6 50.1 52.5 53.6 22.628 29 32.0 35.6 39.7 48.4 21.6 27.3 32.8 37.6 40.6 41.9 43.9 44.8 18.829 30 25.0 27.8 31.0 37.8 16.9 21.3 25.6 29.3 31.7 32.7 34.3 35.0 14.6

Feed back systems

The Mini-lift up is designed to drift with the prevailing current and to place its self under the feed spillage, which has been a problem with the more static solutions on the market. The grid from drain water can be placed on the side of the cage, where excess feed is lifted up by a collector can be viewed directly.

Simple cost effective feed back systems

Systems to monitor and prevent over feeding such as feeding trays

Distance between farms

Minimum distance between farms or farm areas Prevent disease transfer between farms Prevent pollution between farms Allow unimpacted zone between farms for

recolonisation of the sediment Prevent build up of nutrient levels to dangerous

levels

Zoning

Zoning of aquaculture areas To choose the best areas suited for aquaculture Calculate carrying capacity for those zones Limit production within zone (prevent over

production) Restrict impacts to that zone Prevent conflict with other users of the coastline

Use of extractive species

Mollusc or seaweed systems remove nutrients from the culture environment.

Effective integration of fed and “extractive” aquaculture practices can result in increase of productivity and can mitigate against nutrient build up in the environment.

Mixed culture of fish, molluscs and seaweeds practiced in the coastal bays of China is a good example.

However densely located extractive aquaculture systems can cause negative impacts on the environment, especially on sediments, as a result of faecal and pseudofaecal accumulation (Yellow Sea China).

Integrated aquaculture

Integrated aquaculture (IA) is a concept which has been developed to maximize water use efficiency by growing a number of species together or aqua/agri culture.

Increase productivity of scarce freshwater resources and reduce pressure on natural resources.

The three main environments are Irrigated systems, floodplains and inland valley bottoms

In integrated systems, aquaculture there is multiple use of the water and can increase water productivity (e.g. rice-fish farming in Asia).

However there are problems with the continuous supply of water, the use of agrochemicals

Managing the sector at an area level

Planning and management Proper zoning Environmental impact assessments (EIA) evaluation of the carrying capacity of the

environment

Some countries are already applying these tools as requirements for aquaculture licensing

This helps to reduce the negative environmental impacts of aquaculture and encourage establishing sites in suitable locations.

Factors affecting impact

Analysis of monitoring results from 168 environmental surveys on 80 Salmon farm sites in Norway (APN, 2003) has shown that management practices as well as environmental factors play a strong role on the impact of sediments below the cages.

For salmon production in cold waters, management practices such as years in operation (without fallowing) and feeding strategy were found to have greater influence on impact than environmental factors such as current speed and water depth.

Multi-factorial analysis of environmental and management variables on sediment quality

Local carrying capacity

– Depth

– Currents

– Sediment characteristics

– Sediment turnover

Management practices:

– Feeding regime

– Stocking density

– Time-scale of inputs

Historical:– National environmental quality guidelines

for coastal waters (1993) – Standardized monitoring schemes (1997)– National standard for monitoring (2000)

Samples (1996-1998):– 80 fish farms represented– 168 stations in the analysis

Analysis of Management Practices in Norway

Spatial distribution of samples

Close – under cages– 41 samples

Intermediate – 50-100m– 39 samples

Reference – 1000m– 49 samples

Baseline samples– 39 samples

Reference (1000m)

Close (0 m)

Intermediate (50- 100 m)

Main current

Selected Parameters for Analysis

Environmental quality measure (Y-variable)– total organic content (TOC) in sediments

Environmental Variables– particle distribution in the sediments– depth at site – water currents

Management Variables– feed consumption over the last 12 months– number of years site is used in production– abandonment of sites (fallowing)

Categorization of environmental variables

Predicted Sensitivity

Environmental Quality

Univariate Results

Correlations (Spearman Rank Order Test)

Conclusions from this analysis

~ 25% of the sites were heavily effected by organic enrichment

effects were local - 50 to 100 m from the cages, beyond that there was no evidence for increased organic enrichment

depth and speed of water currents are not sufficient as predictors for organic enrichment if used as single variables

fallowing has a strong influence reducing organic enrichment in the sediments

Results from EMMA project

Environmental management of aquaculture should be based on carrying capacity of the lake,

river or bay area Should have strong Government planning based

on science Government should control development and

enforcement of regulations Operator management options should be

encouraged through Codes of Conduct, best practice, etc.

Government planning options

Zoning of aquaculture areas (max production per zone)

placing cages in areas with higher exchange forcing integrated aquaculture (fish and

mollusc/seaweed) zoning (fish - mollusc - fish - mollusc etc.) minimum distance between cages minimum distances between farms mariculture parks (controlled development) controlled fry stocking season/date Large farms to be forced offshore Early warning systems for low oxygen/high algae

conc/poor water exchange

Government management and enforcement of regulations

Regular environmental monitoring of aquaculture zones

Checking licences removing abandoned structures removing unlicensed farms

based on carrying capacity of the lake, river or bay area

Limit number of licences (number of cages, pens, etc)

limit number of structures per licence Limit size of licence (50 tonnes, 100 tonnes/crop) Limit volume of structure (1000 m3) Limit surface area of utilisation limit maximum standing stock biomass (50

tonnes per farm) limit maximum density of stocking (fry per cage) limit maximum density in cage (15 kg/m3) Limit food purchase per farm Limit food delivery per area

Other operator management options

Codes of Conduct Best practice guidelines limit maximum density in cage (15 kg/m3) improved feeding strategy (time, frequency,

quantity) harvesting before risk periods not feeding during risk periods controlled stocking fry to miss high density during

risk periods moving cages after production to new area to

allow fallowing of old area moving further offshore or area with better water

exchange