This is Chapter 13 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
This chapter addresses fisheries and aquaculture in four large marine ecosystems, three in the northern North Atlantic and one in the North Pacific.The ecosystems around Greenland and off northeast Canada (east of Newfoundland and Labrador) are of a true arctic type. Owing to a greater influence of warm Atlantic or Pacific water, the other systems are of a cold-temperate type. Historical data are used to project the effects of a warming climate on commercial and other marine stocks native to these ecosystems.
Modeling studies show that it is difficult to simulate and project changes in climate resulting from the response to forces that can and have been measured and even monitored on a regular basis for considerable periods and on which the models are built. Furthermore, current climate models do not include scenarios for ocean temperatures, watermass mixing, upwelling, or other relevant ocean variables such as primary and secondary production, on either a global or regional basis. As fisheries typically depend on such variables, any predictions concerning fisheries in a changing climate can only be of a very tentative nature.
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 and therefore it is often 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 those in the past 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. Thus the effects of climate change on marine fish stocks and the eventual socio-economic consequences of those effects for arctic fisheries cannot be accurately predicted.
In general, it is likely that a moderate warming will improve conditions for some of the most important commercial fish stocks, e.g., Atlantic cod, herring, and walleye pollock.This is most likely to be due to enhanced levels of primary and secondary production resulting from reduced sea-ice cover. Reduced sea ice would automatically improve recruitment to Atlantic cod, herring, and walleye pollock stocks, as well as to a number of other smaller stocks.
Such changes could also lead to extensive expansions of habitat areas for species such as cod and herring.The most spectacular examples are cod at Greenland and the Norwegian spring-spawning herring. Atlantic cod appear to be unable to propagate off West Greenland except under warm conditions when a very large self-sustaining cod stock has been observed. At the same time, there has sometimes been a large-scale drift of juvenile cod from Iceland to Greenland. Many of these cod have returned to Iceland to spawn as adults, thus expanding the distribution range of Icelandic cod. In warm periods, the Norwegian spring-spawning herring forages for food westward across the Norwegian Sea to the north of Iceland, but is excluded from the western half of the Norwegian Sea and northern Icelandic waters during cold periods.This results in a loss of about a third of the summer feeding grounds for the largest single herring stock in the world.
Global warming is also likely to induce an ecosystem regime shift in some areas, resulting in a very different species composition. In such cases, relative population sizes, fish growth rates, and spatial distributions of fish stocks are likely to change.This will result in the need for adjustments in the commercial fisheries. However, unless there is a major climatic change, such adjustments are likely to be relatively minor and, although they may call for fresh negotiations of fishing rights and total allowable catches, such changes are unlikely to entail significant economic and social costs.
The total effect of a moderate warming of climate on fish stocks is likely 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 and the underlying research. Examples supporting this statement are the collapse of the “northern cod” off Newfoundland and Labrador, the fall and rise of the Norwegian springspawning herring, and the stable condition of the Alaska pollock of the Bering Sea. However, all arctic countries are currently making efforts to implement management strategies based on precautionary approaches, with increasing emphasis on the inclusion of risk and uncertainty in all decision-making.
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. These impacts will be very different to those experienced in earlier times, when the concept of fisheries management was almost unknown. Furthermore, in previous times general poverty, weak infrastructure, and lack of alternative job opportunities meant that the ability of societies to adapt to change, whether at a national or local level, was far less than today.Thus, 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 may, however, be greatly affected.
Chapter 13: Fisheries and aquaculture in the Arctic|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