How will climate change affect the Cold Water Prawn?

Transcription

1 INTERNATIONAL COLD WATER PRAWN FORUM 2013 How will climate change affect the Cold Water Prawn? Paul Wassmann

2 The Arctic Ocean: decisive facts in express speed Photo: R. Caeyers

3 The worlds largest and broadest continental shelves (potential for fisheries!) Deep basins

4 The arctic air temperature increases much more than the gobal Air temperature in the Arctic in 2100: 6-10 C higher

5 Sea ice decreases dramatically: > 5 % per decade. New record in 2012

6 Less ice, more sunlight Is-volumen Ice and sun in concert: The Tequila Sunrise Theory During the last 30 years about 75 % of the ice in the Arctic Ocean has melted The ice is now thin and moves quicker

7 Melting and warming of the surface creates stratification and prohibits vertical mixing Increasing light and warming does imply less ice, but not necessarily increased productivity Less nutrients in the surface layer = less harvestable production

8 The thick multi-year sea ice has already melted. In a few decades the entire sea ice of the Arctic Ocean will melting in summer A new, ice-free, stratified and completely unknown ecosystems will arise Foto: R. Cayers

9 What do we know about the marine ecosystems in the Arctic Ocean?

10 Little. Few comprehensive investigations of marine ecosystem: may be 15 Barents Sea is the best known and best managed of all Arctic ecosystems North of Svalbard? Fram Straight? Nansen basin? Kara Sea? Wassmann 2011

11 Extreme variations in season will disappear Organisms get smaller The size of fish feed decreases, no condition for overindulgence, more even distribution of food over time Sea ice today Sea ice in the near future Wassmann & Reigstad 2011

12 Short conclusion (before we look upon where cold water prawns may feed in the future) The Arctic Ocean exposed to the greatest climate change is still the least investigated marine ecosystems on earth Lack of knowledge is caused by the cold war (earlier), low attention (Siberia), but also territorial border disputes among the Arctic Five. Despite considerable research in latter years we still cannot project into the future in a responsible manner because we do not know the Arctic Ocean well enough before climate warming started Photo: A. Sveen

13 Model for production in the Arctic Ocean Mainly an European view Greenland Alaska Danmark Norway

14 Primary production in todays climate (or yesterdays) Average over 17 years ( )

15 Primary production plant-plankton (grams C m 2 ) Norway

16 Which production can we expect in the future?

17 Today 2100 Primary production (g C m -2 )

18 A European Arctic Corridor perspective

19 Pandalus borealis in the North Atlantic

20 Todays primary production between Greenland and Norway, Svalbard and Russia (g C m -2 ) Grønland Norge Svalbard Grøn

21 Is there a connection between primary production and cold water prawn stocks? Caution: many steps in the chain that leads from primary production to a stock Let us compare

22 Shrimp biomass

23 There is a direct, (but weak) connection between primary production and prawn stocks in colder water Models can predict the primary production of the future. How then will the primary production in the European Arctic change during this century? And what implications may climate warming have for cold water prawns?

24 Increase and decline of primary production

25 Increase and decreases of primary production in the Barents Sea (%) in the forthcoming 80 years Grønland Norge Svalbard Grøn

26 Most likely candidates for increased production in these cold waters are polar cod, prawns and scallops

27 Economic zones

28 Primary production today (g C /m 2 /year Economic zones

29 By 2100 primary production has in/decreased (in percent of today) Norwegian Sea: - 20% Svalbard: - 8% Jan Mayen: - 15% East Greenlandic: - 8% Russian zone: + 55%

30 Less ice implies more light and increased primary production. But increased stratification decreases the harvestable production. A balance Productivity increases in particular in the Kara Sea and along the shelf break to the deep Arctic Ocean Increased microbial activity, longer growth seasons and more competition for food suggest less food for larger organisms At the end of the century fish and prawns will feed over a larger area as compared to today, they will move north- or north-eastwards in the Barents Sea or they may face less food when they remain in todays regions Foto: O.M. Rapp.

31 Like all other bottom-dwelling forms prawns depend on primary production and what is left over in the upper water column and sinks to the bottom It is an insurmountable challenge to derive estimates of recourses upon knowledge of primary production alone Primary production can indicate where prawns may be found in decades to come In the future they may find better feeding grounds north of Svalbard They will probably experience extensive new feeding grounds in the entire Kara Sea and along the outer Siberian shelf Photo: A. Sveen

32 There are few fish competing for food in the cold waters that will experience extensive primary production in decades to come There may be only three commercial species that may utilize the increased primary production: polar cod, scallops and prawns Climate change may favor cold water prawn in the new productive region, but southern region may get lost Russia is the big climate winner in the Arctic Ocean It may be useful to look into the option of getting better access to Russian territorial waters and/or quotas. Or to invest in Russian cold water prawn interests. Photo: A. Sveen

33 Thanks! Photo: A. Sveen

34 How will climate change affect the Cold Water Prawn? Like all other bottom-dwelling forms prawns depend on primary production and what is left over in the upper water column and sinks to the bottom It is an insurmountable challenge to derive estimates of resourses such as fish, prawns and scallops based upon knowledge of primary production Primary production can indicate where prawns may be found in decades to come

35 They will be continously found in the Barents Sea, but may be in smaller quantities than now, in particular in the south. More towards the north-east In the future they may find better feeding ground north of Svalbard

36 They will probably experience extensive new feeding grounds in the entire Kara Sea and along the outer Siberian shelf Russia is the big climate winner in the Arctic Ocean There are few fish that will compete for food in the cold waters that in decades to come will experience extensive primary production That implies that there are three commercial species that may harvest the increased primary production: polar cod, scallops and prawns

37 In the long run.. It may be useful to look into the option of getting access to Russian territorial waters. Or to invest in cold water prawn interests in Russia.

38 Photo: A. Sveen

39 Todays primary production (g C m -2 ) Grønland Svalbard Norge

40 How will climate change affect the Cold Water Prawn? Paul Wassmann Faculty for Biosciences, Fisheries and Economy, University of Tromsø - Norways Arctic University

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44 Foto: R. Cayenz.

45 INTERNATIONAL COLD WATER PRAWN FORUM 2013 How will climate change affect the Cold Water Prawn? Paul Wassmann