This is Section 13.6 of the Arctic Climate Impact Assessment
Lead Authors: Hjálmar Vilhjálmsson, Alf Håkon Hoel; Contributing Authors: Sveinn Agnarsson, Ragnar Arnason, James E. Carscadden, Arne Eide, David Fluharty, Geir Hønneland, Carsten Hvingel, Jakob Jakobsson, George Lilly, Odd Nakken,Vladimir Radchenko, Susanne Ramstad,William Schrank, Niels Vestergaard,Thomas Wilderbuer
Modeling experiments show that it is not easy to project changes in climate due to forces, which can and have been measured and even monitored on a regular basis for considerable periods of time and are the data upon which such models are built.The main reason being that major natural events occur over time scales greater than decades or even centuries and the period of regular monitoring of potentially important forcing events is relatively short. Also, current climate models do not include scenarios for ocean temperatures, watermass mixing, upwelling, and other relevant ocean variables such as primary and secondary production, neither globally nor regionally.Thus, it is not possible to predict the effects of climate change on marine fish stocks with any degree of certainty and so the eventual socio-economic consequences of these effects for arctic fisheries. Nevertheless, and despite these difficulties, the scientific community should still rise to the challenge of predicting reactions of marine stocks in or near the Arctic to climate change, basing initial studies on past records of apparent interactions, however imperfect and inconclusive. It is on such bases – and such bases only – that effective future research can and should be planned and undertaken.
Commercial fisheries in arctic regions are based on a number of species belonging to physically different ecosystems.The dynamics of many of these ecosystems are not well understood. This adds a significant degree of uncertainty to attempts to predict the response of individual species and stocks to climate change. Indeed, to date it has been difficult to identify the relative importance of fishing and the environment on changes in fish populations and biology. Moreover, current fish populations differ in abundance and biology from past populations due to anthropogenic effects (i.e., exploitation rates). As a result it is unclear whether current populations will respond to climate change as they may have done in the past.
Nevertheless, it does appear likely that a moderate warming will improve the conditions for some of the most important commercial fish stocks, as well as for aquaculture. This is most likely to be due to enhanced levels of primary and secondary production resulting from reduced sea-ice cover and more extensive habitat areas for subarctic species such as cod and herring. Global warming is also likely to induce an ecosystem regime shift in some areas, resulting in a very different species composition. Changing environmental conditions are likely to be deleterious for some species and beneficial for others.Thus, relative population sizes, fish growth rates, and spatial distributions of fish stocks are likely to change (see Table 9.11). This will result in the need for adjustments in the commercial fisheries. However, unless there is a major climatic change over a very short period, these adjustments are likely to be relatively minor and are unlikely to entail significant economic and social costs.
The total effect of climate change on fish stocks is probably going to be of less importance than the effects of fisheries policies and their enforcement.The significant factor in determining the future of fisheries is sound resource management practices, which in large part depend upon the properties and effectiveness of resource management regimes. All arctic countries are currently making efforts to implement management strategies based on precautionary approaches, with increasing emphasis on ecosystem characteristics, effects of climate changes, and including risk and uncertainty analyses in decision-making. Ongoing adjustments to management regimes are likely to enhance the ability of societies to adapt to the effects of climate change.
The economic and social impacts of altered environmental conditions depend on the ability of the social structures involved, including the fisheries management system, to generate the necessary adaptations to the changes. It is unlikely that the impact of the climate change projected for the 21st century (see Chapter 4) on arctic fisheries will have significant long-term economic or social impacts at a national level. Some arctic regions, especially those very dependent on fisheries or marine mammals and birds in direct competition with a fishery may, however, be greatly affected. Local communities in the north are exposed to a number of forces of change. Economic marginalization, depopulation, globalization-related factors, and public policies in the different countries are very likely to have a stronger impact on the future development of northern communities than climate change, at least over the next few decades.
This chapter considers the possible effects of projected climate change on four major ecosystems: the Northeast Atlantic (Barents Sea), the central North Atlantic (Iceland/Greenland), Northeast Canada (Newfoundland/ Labrador), and the North Pacific (Bering Sea).There are substantial differences between these regions in that the Barents Sea and Icelandic waters are of a subarctic/ temperate type, while the arctic influence is much greater in Greenland waters, the waters off northeast Canada, and the Bering Sea. It follows, therefore, that climate change need not affect these areas in the same or a similar manner. Also, the length of useful time series on past environmental variability and associated changes in hydrobiological conditions, fish abundance, and migrations varies greatly among regions. Finally, there are differences in species interactions and variable fishing pressure, which must also be considered.
Owing to heavy fishing pressure and stock depletions, the Barents Sea, Icelandic waters, and possibly also the Bering Sea could, through more efficient management, yield larger catches of many fish species. For that to happen research must increase, and more cautious management strategies must be developed and enforced. However, a moderate warming could enhance the rebuilding of stocks and could also result in higher sustainable yields of most stocks, among others, through enlarged distribution areas and increased availability of food in general. On the other hand, warming could also cause fish stocks to change their migratory range and area of distribution. This could (as history has shown) trigger conflict among nations over distribution of fishing opportunities and would require tough negotiations to generate viable solutions regarding international cooperation in fisheries management.
The waters around Greenland and off northeast Canada are very different from the above.These regions are more arctic in nature. Greenland appears unable to support subarctic species such as cod and herring except during warm periods. Examples from the 20th century prove this point. For example, there were no cod in the first two and a half decades, but a large local self-sustaining cod stock from 1930 until the late 1960s, apparently initiated by larval and 0-group drift from Iceland. If current climate conditions remain unchanged little change is likely around Greenland. On the other hand, a “moderate warming” such as that between 1920 and the late 1960s is likely to result in dramatic changes in species composition – a scenario where cod would play the major role. The northeast Canadian case is an extreme example of a situation where a stock of Atlantic cod (the so-called “northern” cod), which had sustained a large fishery for at least two centuries, is suddenly gone. Opinion differs as to how this has happened; most people believe that the decline was due entirely to overfishing, whereas others think that adverse environmental factors were significant contributors. In the present situation, however, the northern cod stock is so depleted that it is very likely to take decades to rebuild – even under the conditions of a warming climate
An evaluation of what could happen to marine fisheries and aquaculture in the Arctic should the climate warm by more than 1 to 3 ºC is not attempted in the present assessment.This is beyond the range of available data and would be of limited value. In general terms, however, it is likely that at least some of the ecosystems would experience reductions in present-day commercial stocks which might be replaced partially or in full by species from warmer waters.
Chapter 13: Fisheries and Aquaculture
13.2 Northeast Atlantic – Barents and Norwegian Seas
13.3 Central North Atlantic – Iceland and Greenland
13.4 Newfoundland and Labrador Seas, Northeastern Canada
13.5 North Pacific – Bering Sea
13.6. Synthesis and key findings
13.7. Research recommendations