Impact of climate change on fisheries. Keith Brander ICES/GLOBEC Coordinator

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1 Impact of climate change on fisheries Keith Brander ICES/GLOBEC Coordinator

2 It comes up to the shore here from the great fish pond which is the Icelandic Sea, towards the winter when the great part of other fish have left the land. And the herring does not seek the shore along the whole, but at special points which God in his Good Grace has found fitting, and here in my days there have been two large and wonderful herring fisheries at different places in Norway. The first was between Stavanger and Bergen and much further north, and this fishery did begin to diminish and fall away in the year And I do not believe there is any man to know how far the herring travelled. For the Norwegian Books of Law show that the herring fishery in most of the northern part of Norway has continued for many hundreds of years, although it may well be that in punishment for the unthankfulness of men it has moved from place to place, or has been taken away for a long period. Clergyman Peder Claussøn Friis ( ) 1614)

3 Northward extension of cod fishery to late 1930 s. Published in1939

4 Climate has always had impacts on fisheries We can learn from past periods of warming Situation now is different because Change is rapid and moving outside past experience Fisheries and marine ecoystems are more stressed than in the past

5 Increase in sea surface temperature over the past 25 years

6 How confident are we that climate change has an impact? Very confident that major changes during the past century were due to climate changes in fish and other biota at Iceland and Greenland distribution changes (fish, benthos, plankton, sea birds) decline of Canadian cod stocks ( also due to overfishing and to cooling, not warming) North Pacific fisheries

7 What does climate do to fish? Distributions change Productivity changes Some species decline and others become more abundant

8 Climate shifts perturb fisheries and have socio-economic impacts s Late 1960 s Late 1970 s (from Anderson and Piatt, 1999) Bottom trawl surveys, Pavlov Bay, AK (from Botsford et al. 1997)

9 Climate shifts perturb fisheries and have socio-economic impacts s Late 1960 s Late 1970 s (from Anderson and Piatt, 1999) Bottom trawl surveys, Pavlov Bay, AK (from Botsford et al. 1997)

10 Climate shifts perturb fisheries and have socio-economic impacts s Late 1960 s Late 1970 s (from Anderson and Piatt, 1999) Bottom trawl surveys, Pavlov Bay, AK (from Botsford et al. 1997)

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12 How urgent is it to tackle climate impacts on fisheries? Depends on how quickly climate changes over next 20 to 50 years (and on sensitivity of biota to change) Tackling excess fishing is much more urgent pressures of fishing and climate interact so the issues are interrelated [Mitigation actions are very urgent]

13 State of exploitation of marine capture fisheries (FAO 2007) recovering depleted overexploited fully exploited moderately exploited under exploited unknown

14 How confidently can we predict future impacts? Depends on how confident climatologists are about changes over next years? Temperature, salinity, oxygen, ph, wind, stratification, nutrients extreme events as well as changes in means Even with good climate predictions we can only predict a few biological responses with confidence

15 What does climate do to fish? (1) Direct effects on growth, maturity, survival, reproduction these affect production and resilience Cod growth experiment Cod recruitment meta-analysis 1 yr old fish per ha Greenland NE Arctic Iceland North Sea Irish Sea Surface temperature (weeks 14-26) Sensitive range Less sensitive range

16 What does climate do to fish? (2) Indirect effects via effects on food, parasites, competitors etc. Cod growth should increase as temperature rises to 8.5 o C but if their forage species decline at this temperature then growth will decline (cod-capelin at Iceland)

17 What does climate do to fish? (3) We can define bioclimate envelopes based on temperature and other factors. These help to define where a species is expected to occur and also to predict changes in distribution as climate changes.

18 How do we increase our confidence? Use the past as an analogue for the future warm period; Historic reconstructions Understand processes and represent them in predictions and models salinity and cod ; nutrient supply (vertical mixing, aeolian) Do experiments like crop experiments;

19 Summing up Fisheries have always been affected by climate - productivity (recruitment, growth, mortality, distribution) is affected This means that biological reference points (biomass, F) and management based on them need to adjust Climate and fishing are interacting pressures on fish stocks Climate can increase as well as decrease fish productivity

20 Reduce fishing pressure A triple-win, no regret strategy More resilient populations and ecosystems (enhances adaptation) Lower use of fuel (mitigation of GHG emission) Higher yields (most stocks overfished)

21 Conclusions We must lower fishing mortality on stocks whose productivity is reduced by climate Because climate change is taking us into unknown territory our management must be alert to change and responsive Early detection of changes requires monitoring and interpreting biological warnings Systems with tipping points (e.g. Baltic) need special attention

22 Are we prepared? For a 1 to 2m rise in sea-level by 2100? For the disappearance of Baltic cod? For an increase in the Greenland cod stock (and the relationship with Iceland) We cannot predict any of these with much confidence at present, but can work to put likelihoods on them and include them in strategic evaluation of risk and uncertainty.