Lecture on Sea fisheries- and integrated marine environment management in Conservation Biology course University of Oslo spring2013

1. Centre for Ecological and
Evolutionary Synthesis
Sea fisheries- and
integrated marine environment management
Geir Ottersen
Bio4150-9150 15/4-2013

2. I’ll be talking about
• Traditional fisheries management
• Fisheries management within the precautionary principle
• Ecosystem based fisheries management
• Examples of failed and successful fisheries management
• Integrated management plans for
the North, Norwegian, and Barents Seas
• The Arctic Ocean

3. Maximum sustainable yield
Principle: catch = population growth surplus
MSY is, theoretically, the largest catch that can be taken from
a stock over an indefinite period.
MSY aims to maintain the population size at the point of
maximum growth rate by harvesting the individuals that would
normally be added to the population, allowing the population
to continue to be productive indefinitely.

4. MSY assumes logistic growth
dN
=
dt
K-N
K
N·R
maximum
growth rate
reduction due
to competition,
density-
dependence
carrying
capacity
K-N
K
N·R·
N
K/2 K0
Pop. growth
(”production”)
Decrease in
production because
of dd effects
Small production
because of few fish
Max catch= max production= MSY

5. MSY was a leading fisheries management strategy until well into
the 1980s, is still used, but has a number of serious weaknesses:
- The concept is often difficult to apply in practice, ignores uncertainty
- Purely single species, no consideration of trophic interactions
- Tends to treat all individuals in the population as identical,
ignoring size and age structure
- Doesn’t take into account that productivity varies with environmental conditions
- Doesn’t account for spatial variability in productivity
- Ignores the issue of bycatch

6. Biological reference points – the precautionary principle I
Biological reference points represent either a level of fish mortality
or a level of the spawning stock.
Since 1998, ICES has defined precautionary-principle reference points
and attempted to quantify these for most stocks.
overfished and
overfishing
overfished
overfishing

7. Blim - a bottom limit for the spawning stock of a species
If the spawning stock falls under that limit,
there is great chance of poor recruitment
Flim - an upper limit for fishing mortality
If this limit is exceeded over a long period,
there is a high probability that the stock will fall below Blim
The precautionary approach implies that the stock should be kept well
above Blim and so a precautionary level (Bpa) is set at a higher level which
gives reasonable certainty that the stock will stay above Blim
Precautionary fishing mortality Fpa < Flim
Biological reference points – the precautionary principle II

8. Management strategies: Quotas
• Three main strategies for the setting of quotas:
1. Constant quotas
+ : economical/societal benefits of stable catch
- : unstable – a small stock may be fished out
not economically optimum yield for large stocks
2. Constant harvest rate (constant % of biomass caught)
+ : catch every year
- : not economically optimum yield
3. Constant escape (constant biomass escapes catch)
+ : economically optimum yield
- : economical/societal drawback of unstable catch levels
(some years no catch at all)

9. • Additional strategy to quotas: Some areas with no fishing/catch
• Best suited for demersal fish and evertebrates with relatively
small migration (flatfishes, lobster, scallops)
• Not well suited for highly migratory fish (mackerel, herring..)
(with different habitats according to life stage and season)
Management strategies: Marine reserves/protected areas

10. Four small reserves established in 2006
• Already in 2010 clear trend towards many more lobsters in the areas
• Significant increase in mean size/length
• No increase in lobster numbers in control areas with lobster fishing
Management strategies: Marine reserves/protected areas
Example: Lobster reserves around the Norwegian Skagerrak coast:

11. Traditional fisheries legislation only regulates
the relation between fishers and ressource
A move from single species to ecosystem based management
Graphics from WWF

12. Modern fisheries legislation ”Havressursloven” regulates the
relation between fishers and the whole ecosystem
Graphics from WWF

13. Example of failed management 1: Labrador-Newfoundland cod
• The fishery was of great economical, societal and political
importance from the 1500s
• Dramatic collapse of the stock around 1990-1991
• The fishery was stopped in July 1992 and there is still no
indication of a full-scale reopening
• 35000 Canadians lost their jobs

14. • Reasons for the collapse:
1. Stock estimates based upon ”catch per unit effort” (CPUE).
Fish concentrated in large shoals as numbers dropped →
stock size overestimated
2. High unaccounted mortality due to bycatch and dumping of
too small/unwanted fish
3. Simultaneously the climate changed towards colder
unfavourable conditions
4. Rebuilding of the stock is extremely slow – has the
ecosystem switched to an alternative stable state with more
shrimps, crabs and marine mammals?
Example of failed management 1: Labrador-Newfoundland cod

15. • Huge stock during the 1950s
• Long lived → a few good year classes is enough to give a large stock over a
prolonged period (e.g., 1950s)
• Stock more or less wiped out by the late 1960s/early 1970s
Example of failed management 2: NSS herring in the 1960s
WHY?
 Catch efficiency increased during the 60s (sonar, power block, synthetic nets)
 Dense schools also at low numbers (catchability still high)
 Catch (too) high as late as 1969
 Cold unfavourable conditions

16. • Herring and cod normally produce
many recruits in warmer years
• 1983: Warm year, good year class of
herring and cod at early stages →
researchers and managers predicted
good cod fishery in the late 1980s
Example of failed management 3: The Barents Sea in the 1980s
What happened:
Predation by cod and herring and fishery caused the capelin stock to collapse →
crisis in the cod fishery in the late 1980s →
- 100 000 harp seals ”grønlandssel” seeking food towards the coast drowned in nets
- 200 000 sea birds died
BUT
 One did not take into consideration that
1-2 year old herring eat capelin larvae
 Capelin is the key prey for cod
(rich in fat)

17. Common factors behind mismanagement examples
1. Overestimated stock size (Newfoundland cod, NSS herring) –
typically based upon catch-per-unit-effort
2. Underestimated mortality due to bycatch (Newfoundland cod)
or predation by other species (Barents Sea capelin)
3. Environmental shifts changes the sustainable catch level
(Newfoundland cod, NSS herring)
4. Ignorance of trophic interactions (Barents Sea, lack of
rebuilding of Newfoundland cod)

18. The stock is doing well!
Total stock estimate: 3.5 million tonnes
Expected spawning stock 2013: 2.2 million tonnes
Blim: 220 000 tonnes
Bpa : 460 000 tonnes
Catch 2011: 720 000 tonnes
Norwegian catch 2011: 332 000 tonnes
Norwegian catch 2011 value: 3.9 billion NOK
Agreed quota for 2013: 1 million tonnes
Examples of successfull management: Barents Sea cod now I

19. Examples of successfull management: Barents Sea cod now II
Why are we doing well now?
Better management practices
• HCR implemented
• IUU fishing reduced
Luck (favourable climate)
IMR’s SURVEY ON SPAWNING COD - ”SKREI”
2013
Late March 2013:
Enormous amount of
spawning cod – new record!

20. Integrated management plans
”Meldinger til Stortinget”
White papers to the Parliament
Norwegian Sea 2009
Barents Sea 2006
revised and updated 2011
North Sea 2013,
being finalized now

21. The Norwegian Sea

22. Status reports
by sector
Report on
societal issues
Vulnerability of
areas of particular
biological value
Integrated management plan for the Norwegian Sea
” Melding til Stortinget”
Environmental impact assessment by sector
Indicators, reference values
and action thresholds
Maritime
transport Fisheries
External
pressures
Assessment of cumulative effects
Conflicts Needs for further Cumulative
of interest knowledge effects
Petroleum/
energy
Description of the
environment including
areas of particular
biological value

23. The North Sea

24. Human impact on the North Sea

25. Report on vulnerability of
particularly valuable areas
The North Sea
Area report including environmental
and ressource description

26. Identification of areas of particular biological value
With areas of particular biological value we mean:
- Areas that are important for biological production
- Areas that are important for biodiversity
Within these two main criteria are a wide range of sub-criteria
The North Sea

27. 1 - Bremanger to Ytre Sula
2 - Korsfjorden
3 - Karmøyfeltet
4 - Boknafjorden/Jærstrendene
5 - Listastrendene
6 - Siragrunnen,
7 - Transekt Skagerrak,
8 - Ytre Oslofjord
9 - Skagerrak
10 - sandeel grounds
11 - sandeel grounds
12 - mackerel grounds
+ coastal zone
North Sea: Areas of
particular biological value

28. North Sea: Areas of
particular biological value
1 - Bremanger to Ytre Sula
2 - Korsfjorden
3 - Karmøyfeltet
4 - Boknafjorden/Jærstrendene
5 - Listastrendene
6 - Siragrunnen,
7 - Transekt Skagerrak,
8 - Ytre Oslofjord
9 - Skagerrak
10 - sandeel grounds
11 - sandeel grounds
12 - mackerel grounds
+ coastal zone

29. Example:
Area 7 - Transect Skagerrak
The aim is to protect the sub-surface
landscape with its plant and animal
life, representative of Skagerrak with
the broad range of nature types
present. The area spans from waters
sheltered between islands and
skerries to strongly exposed offshore
regions.
From National plan for marine protected areas

30. Example:
Areas 10-11: Sandeel ”tobis”
spawning/wintering areas
Sandeel is an ecologicaly
and commercially important
fish species in the North Sea

31. Vulnerability of the biologically valuable areas
Vulnerability is here a measure of how and
how much an activity influences the identified valuable area
The vulnerability of each of the biologically particularly valuable areas
was assessed in terms of the resilience of species and habitats to
anthropogenic pressures.
Pressures include fisheries, maritime transport, petroleum activities
and long-range transboundary pollution.

32. Area of
especial value
Value Vulnerability
Present activity level
Possible future
activity level
Normal activity
Acute
accidents
SVO 10:
Vikingbanken
Spawning
and habitat
area for
sandeel,
feeding area
for whale
Impacted by fisheries,
toxic substances,
marine waste
Vulnerable to heavy
fishing of sandeel,
environmentally
hazardeous substances
and marine waste
Vulnerable to
oil pollution
from accidents
with oil
spills from
ships or
platforms
Vulnerable to
heavy fishing,
oil pollution and
area use by
petroleum
activities
Vulnerability evaluation (example)

33. The Barents Sea
revised and updated report

34. Fisheries activity 2009
(vessels > 21 m)
Ship traffic
2nd half of 2010
Prospects for petroleum
extraction mapped 2007-2009

35. Areas of particular biological value and vulnerability (in green)

36. Nature types of particular biological value and
vulnerability Lofoten-Vesterålen-Troms

37. Examples of red-listed species in the area

38. A new ocean opening for human use – how to manage it?

39. Minimum in 1979
MINIMUM ICE COVERAGE

40. Suggested by IMR for Norwegian part:
A baseline study:
- Planning of a joint survey in the Arctic Ocean
(using the new ice-going vessel) scheduled for autumn 2016
Scientific research includes
- Evaluate the impact of changes in productivity and possible
restructuring of the Arctic marine ecosystem
- Investigate the interplay between the Arctic Ocean and
the shallow shelves
- Evaluate environmental risks of human activities
ARCTIC OCEAN:
- Mostly international waters – makes management complex
- Arctic council will play an important role
(Nordic countries, USA, Canada, Russia)

41. Do we expect expansion of Barents Sea
fish populations into the Arctic?
“Atlantic cod have a low potential to establish spawning
grounds in the Arctic….demersal shelf species”
Hollowed et al. Fish. Oceanogr. 2012
COD
Distribution autumn 2012

42. Do we expect expansion of Barents Sea
fish populations into the Arctic?
“Capelin potentially could expand in the Arctic if prey
concentrations were sufficient to sustain increased populations”
Hollowed et al. Fish. Oceanogr. 2012
CAPELIN (LODDE)
Distribution autumn 2012

43. That’s all,
thanks for your attention