Transcript Akvaplan-niva presentation

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
Feed Type
Moisture
FCR
(%) Wet to wet
Trash fish
- 85
12:1
Moist
- 30 3:1
Dry
- 10 2:1
Dry (Norway) - 10 1.1:1
FCR
Dry to wet
1.8:1
2.1:1
1.8:1
1:1
Dry Feed
 Addition of a higher percentage of digestible proteins
 Extruded feed vs pelleted feed
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 - timing
Oxygen levels inside a fish pen
6
5
mg O2
4
3
2
1
Feeding
0
8:00
10:00
12:00
14:00
16:00
18:00
20:00
Tim e
22:00
0:00
2:00
4:00
6:00
8:00
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
min
max
mean weight (gr.)
35
48
48
60
12
14
14
16
16
18
18
20
20
22
22
24
24
26
26
27
27
28
28
29
29
30
0.19
0.43
0.75
1.28
1.92
2.43
3.02
3.25
3.30
2.60
1.95
0.15
0.34
0.59
1.03
1.59
2.04
2.54
2.74
2.78
2.19
1.64
60
80
80
100
100
150
150
200
200
250
250
300
300
350
350
400
400
450
450
500
500
600
0.12
0.26
0.46
0.81
1.27
1.66
2.06
2.22
2.25
1.78
1.33
0.11
0.24
0.42
0.74
1.15
1.49
1.85
1.99
2.02
1.59
1.20
0.10
0.22
0.38
0.65
0.99
1.26
1.57
1.69
1.72
1.35
1.02
0.07
0.17
0.31
0.52
0.78
1.00
1.24
1.34
1.36
1.07
0.80
0.07
0.15
0.27
0.46
0.70
0.89
1.10
1.19
1.21
0.95
0.71
0.06
0.14
0.24
0.41
0.62
0.79
0.99
1.06
1.08
0.85
0.64
0.05
0.12
0.21
0.36
0.54
0.69
0.86
0.92
0.94
0.74
0.55
0.05
0.10
0.17
0.30
0.45
0.57
0.71
0.77
0.78
0.62
0.46
0.05
0.09
0.16
0.27
0.40
0.51
0.64
0.69
0.70
0.55
0.41
0.05
0.09
0.14
0.24
0.36
0.46
0.57
0.61
0.62
0.49
0.37
0.04
0.08
0.12
0.20
0.30
0.40
0.50
0.53
0.54
0.42
0.32
Optimal temperature for growth is 28 'C
Optimal feeding rates
DAILY FEEDING RATE (SFR)
Temp
min
max
mean weight (gr.)
35
48
48
60
12
14
14
16
16
18
18
20
20
22
22
24
24
26
26
27
27
28
28
29
29
30
0.8
0.9
1.3
1.9
2.4
2.9
3.6
4.1
4.3
3.6
2.8
0.6
0.7
1.0
1.6
2.0
2.4
3.1
3.5
3.7
3.1
2.4
60
80
80
100
100
150
150
200
200
250
250
300
300
350
350
400
400
450
450
500
500
600
0.5
0.6
0.8
1.3
1.7
2.1
2.6
3.0
3.2
2.7
2.1
0.5
0.6
0.8
1.2
1.6
2.0
2.5
2.8
3.0
2.5
2.0
0.5
0.6
0.8
1.2
1.5
1.8
2.3
2.6
2.7
2.3
1.8
0.4
0.5
0.7
1.1
1.4
1.6
2.0
2.3
2.5
2.1
1.6
0.4
0.5
0.7
1.0
1.3
1.5
1.9
2.2
2.3
1.9
1.5
0.4
0.5
0.6
0.9
1.2
1.4
1.8
2.0
2.2
1.8
1.4
0.3
0.4
0.6
0.9
1.1
1.3
1.6
1.9
2.0
1.7
1.3
0.3
0.4
0.5
0.8
1.0
1.2
1.5
1.7
1.8
1.5
1.2
0.3
0.4
0.5
0.7
0.9
1.1
1.4
1.5
1.6
1.4
1.1
0.3
0.3
0.4
0.6
0.8
1.0
1.2
1.4
1.5
1.3
1.0
0.3
0.3
0.4
0.6
0.7
0.9
1.1
1.3
1.4
1.1
0.9
optimal temperature for food consumption is 28 'C
Optimal feed conversion rate
FEED CONVERSION RATE (FCR)
Temp
min
max
mean weight (gr.)
35
48
48
60
12
14
14
16
16
18
18
20
20
22
22
24
24
26
26
27
27
28
28
29
29
30
4.00
2.15
1.72
1.49
1.25
1.18
1.19
1.25
1.32
1.40
1.45
4.07
2.18
1.74
1.51
1.27
1.20
1.21
1.27
1.34
1.42
1.48
60
80
80
100
100
150
150
200
200
250
250
300
300
350
350
400
400
450
450
500
500
600
4.31
2.31
1.85
1.60
1.34
1.27
1.28
1.34
1.42
1.50
1.56
4.56
2.44
1.95
1.69
1.42
1.34
1.35
1.42
1.50
1.59
1.65
4.87
2.61
2.09
1.81
1.52
1.43
1.45
1.52
1.60
1.70
1.77
5.54
2.97
2.38
2.06
1.73
1.63
1.65
1.73
1.82
1.93
2.01
5.85
3.13
2.51
2.17
1.82
1.72
1.74
1.82
1.92
2.04
2.12
6.13
3.28
2.63
2.28
1.91
1.80
1.82
1.91
2.01
2.14
2.22
6.47
3.47
2.77
2.40
2.01
1.90
1.92
2.01
2.13
2.25
2.35
6.93
3.71
2.97
2.57
2.16
2.04
2.06
2.16
2.28
2.42
2.51
7.15
3.83
3.06
2.65
2.23
2.10
2.12
2.23
2.35
2.49
2.59
7.36
3.94
3.15
2.73
2.29
2.17
2.19
2.29
2.42
2.57
2.67
7.70
4.12
3.30
2.86
2.40
2.27
2.29
2.40
2.53
2.68
2.79
optimal temp for Food conversion rate is 24 'C
Optimal number of pellets per day
NUMBER PELLETS PER DAY AND FISH
feed
size
pellets / kg
Mistral21
3
21250
Temp
min
max
Mistral21
3
21250
mean weight (gr.)
35
48
48
60
12
14
14
16
16
18
18
20
20
22
22
24
24
26
26
27
27
28
28
29
29
30
6.8
8.2
11.4
16.8
21.1
25.2
31.7
35.8
38.3
32.0
25.0
7.1
8.6
11.8
17.8
23.1
28.1
35.2
39.8
42.6
35.6
27.8
Mistral21
3
21250
Mistral21
3
21250
Mistral21
5
7520
Mistral21
5
7520
Mistral21
5
7520
Mistral21
5
7520
Mistral21
5
7520
Mistral21
5
7520
Mistral21
5
7520
Mistral21
5
7520
Mistral21
7
3150
60
80
80
100
100
150
150
200
200
250
250
300
300
350
350
400
400
450
450
500
500
<
7.5
9.1
12.5
19.2
25.5
31.3
39.3
44.4
47.5
39.7
31.0
9.4
11.4
15.7
23.8
31.2
38.2
47.9
54.1
57.9
48.4
37.8
4.5
5.4
7.5
11.1
14.1
17.0
21.4
24.1
25.8
21.6
16.9
5.4
6.8
9.6
14.1
17.8
21.5
27.0
30.4
32.6
27.3
21.3
6.5
8.2
11.5
17.0
21.5
25.9
32.5
36.7
39.3
32.8
25.6
7.9
9.5
13.2
19.5
24.6
29.6
37.2
41.9
44.9
37.6
29.3
8.5
10.3
14.2
21.0
26.6
32.0
40.2
45.3
48.6
40.6
31.7
9.4
10.7
14.6
21.6
27.4
33.0
41.4
46.8
50.1
41.9
32.7
10.7
11.5
15.2
22.6
28.7
34.6
43.5
49.1
52.5
43.9
34.3
12.0
12.0
15.5
23.0
29.2
35.3
44.3
50.0
53.6
44.8
35.0
5.1
5.3
6.8
9.3
11.9
14.9
18.8
21.1
22.6
18.8
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
Analysis of Management Practices in Norway
 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
Spatial distribution of samples
 Close – under cages
– 41 samples
 Intermediate – 50100m
– 39 samples
 Reference – 1000m
– 49 samples
 Baseline samples
– 39 samples
Close
(0 m)
Main
current
Intermediate
(50- 100 m)
Reference
(1000m)
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
Current
speed
Class
Classification
<3
4
very sensitive
4–6
3
moderately sensitive
7 – 10
2
slightly sensitive
10 - 25
1
not sensitive
Predicted
Sensitivity
Normalized Class
-1
TOC (mg g )
Environmental
Quality
Environmental
classification
<20
1
excellent
20-27
2
good
27-34
3
intermediate
34-41
4
poor
>41
5
very poor
Univariate Results
Variable
Fish feed over the past 12 months (tons)
Number of years in operation
Depth of the site (m)
Average current speed (cm/s)
Classification and Frequency
0-249
250-499
500-999
> 1000
27%
27%
19%
27%
<2
2-4
4-6
>6
32%
17%
27%
24%
<25
25-50
50-75
>75
7%
41%
34%
17%
<3
4-6
7-10
10-25
24%
51%
15%
10%
Correlations (Spearman Rank Order Test)
Variable
Depth
Years of
Operation
Feed
Level
Fallowing
Currents
Correlation
0.0244
0.0648
0.1580
-0.4652
0.2715
P-Value
0.8787
0.6855
0.3220
0.0023
0.0857
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