Arctic marine fisheries provide an important food source globally, and a vital part of the economy of the region. Because they are largely controlled by factors such as local weather conditions, ecosystem dynamics, and management decisions, projecting the impacts of climate change on marine fish stocks is problematic. There is some chance that climate change will induce major ecosystem shifts in some areas that would result in radical changes in species composition with unknown consequences. Barring such shifts, moderate warming is likely to improve conditions for some important fish stocks such as cod and herring, as higher temperatures and reduced ice cover could possibly increase productivity of their prey and provide more extensive habitat.

Greenlandic Cod and Climate

A striking example of a positive climate-related impact involves West Greenland cod. Under the very cold conditions between around 1900 and 1920, there were few cod around Greenland. In 1922 and 1924, large numbers of cod were spawned in Icelandic waters and drifted from Iceland to East Greenland and then to West Greenland where they flourished, resulting in the start of a significant fishery beginning in the mid- to late 1920s. Large numbers of these cod returned to Iceland to spawn in the early 1930s and then remained there. However, many other cod stayed and spawned off West Greenland, giving rise to an independent, self-sustaining cod stock. During the warm period that spanned the middle of the 20th century, the Greenland cod stock grew very large, sustaining an annual average catch of about 315,000 tonnes between 1951 and 1970. The cold conditions that have prevailed since about 1965 appear to have rendered cod incapable of reproducing in Greenlandic waters. The only significant catches since then have been based on fish born in Icelandic waters in 1973 and 1983 that drifted to Greenland from Iceland.

While projected conditions are likely to benefit some species, such as cod, they are likely to negatively affect others, such as northern shrimp, necessitating adjustments in commercial fishery operations. The area inhabited by some arctic species, including northern shrimp, will probably contract and the abundance of those species decrease. This would reduce the large catch (about 100,000 tonnes a year) of northern shrimp currently taken from Greenlandic waters. Furthermore, northern shrimp are an important part of the diet of cod in the waters off Greenland. Thus, if the cod stock were to grow as it did in the last century, the decline in the northern shrimp population could negatively affect the diet and growth of the cod stock. Because the commercial value of a healthy cod stock would be much greater than the value of the shrimp catch, the shrimp fishery would have to be curtailed even further.

Climate, Overfishing, and Norwegian Herring

In the early 1950s, the stock of Norwegian spring-spawning herring was as large as 14 million tonnes, the world's largest herring stock, and was important to Norway, Iceland, Russia, and the Faroe Islands. At that time, these herring migrated west across the Norwegian Sea to feed in the zooplankton-rich waters north and east of Iceland as well as in the oceanic area between Iceland and the island of Jan Mayen (71°N, 8°W). In 1965, a sudden and severe cooling of these waters resulted in the decimation of the tiny crustacean (Calanus finmarchicus) that was by far the most important single food item in the diet of these herring. The herring’s feeding areas were displaced to the east and northeast by several hundred nautical miles, thus placing the stock under severe environmental stress. In the 1960s, the stock was also subjected to severe overfishing and collapsed during the latter half of the decade. Although high fishing intensity of both adults and juveniles was the primary reason for the collapse, the climatic cooling probably contributed to the decline.

In the 1970s, the small numbers of herring that were left did not need to search far to feed and thus stayed close to the Norwegian shore. What was left of the fishery was strictly regulated, and fishing was prohibited for several years. These restrictions, coupled with favorable climatic conditions, contributed to the stock's increase to three to four million tonnes and limited fishing began again. In 1995, the stock reached five million tonnes and extended its feeding grounds and migratory range into international waters. The stock therefore became available for fishing outside Norway's jurisdiction, making the Norwegian management regime insufficient to protect the stock and threatening its continued recovery. In 1996, an agreement was reached between Norway, Russia, Iceland, the Faroe Islands, and the European Union to set quotas for allowable catches of Norwegian spring spawning herring. Such agreements will be crucial in the future as climate change alters fish stocks and their ranges.

Climate Shifts and Fisheries Impacts

A climate shift occurred in the Bering Sea in 1977, abruptly changing from a cool to a warm period, perhaps a reflection of the Pacific Decadal Oscillation. The warming brought about ecosystem shifts that favored herring stocks and enhanced productivity for Pacific cod, skates, flatfish, and non-crustacean invertebrates. The species composition of living things on the ocean floor changed from being crab-dominated to a more diverse mix of starfish, sponges, and other life forms. Historically high commercial catches of Pacific salmon occurred. The Walleye pollock catch, which was at low levels in the 1960s and 1970s (two to six million tonnes), has increased to levels greater than ten million tonnes for most of the years since 1980.

For most of the North Atlantic, the total effect of climate change on arctic and sub-arctic fish stocks is likely to be of lesser magnitude than the effects of fisheries management, at least for the next two to three decades. This is mainly due to the relatively small warming expected for the first part of the 21st century in this area. In the Bering Sea, however, rapid climate change is already apparent, and its impacts significant. The Bering Sea is experiencing a major warming in bottom water temperature that is forcing cold-water species of fish and mammals northward and/or into decline. The first concern of Bering Sea fisheries management is thus likely to be managing for the ecosystem reorganization that is and will continue to be taking place as a result of climate change.

While it seems unlikely that climate change effects on fisheries will have long-term arctic- wide social and economic impacts, certain areas that are heavily dependent on fisheries are likely to be affected. Very severe dislocations are possible and have occurred historically. For example, when the Labrador/Newfoundland cod fishery collapsed due to overfishing, shifts in oceanic conditions, and other factors in the early 1990s, many cod fishermen went out of business or switched to other species, and the value of the fish catch in the province declined sharply. The cod stock has still not recovered, although a decade has passed. The shrimp and crab fisheries that eventually replaced the cod fishery are much less labor intensive and employ far fewer people, although the total commercial value of the fishery is about twice the value of the cod fishery. So while the fishing industry can generally adapt at the national level, particular people and places can be strongly affected.

Seal Hunting, Fishing, and Climate Change in West Greenland:  A Historical Perspective

Historical changes in West Greenland provide a good example of the relationship between climate change and associated social and economic changes. A climatic variation resulted in warming of the waters to the south and west of Greenland in the 1920s and 1930s, causing seal populations to shift northward, making seal hunting more difficult for the local Inuit. At the same time, cod (as well as halibut and shrimp) moved into the warmer waters, enabling the development of a cod fishery. Some local people, such as those in the west coast town of Sisimiut, were able to take advantage of the opportunities that arose due to social and technological factors. Sisimiut became an important fishing center with other new industries and a diverse economic base. This stands in contrast to the development of the southwest Greenlandic town of Paamiut around the same time. Paamiut’s development was based largely on plentiful resources of cod. With few other resources available in commercially viable quantities, there was little incentive to diversify the local economy. The concentration on a single resource made the town vulnerable to environmental change. When the cod population began to fall, due to a combination of climatic change and overfishing, the economy and population of Paamiut declined as a result. This points to the importance of recognizing in any adaptive strategy that local conditions (environmental, social, economic, technological, etc.) are important factors in determining the success of a region subject to change.
 

Arctic marine fisheries provide an important food source globally, and a vital part of the economy of the region. Because they are largely controlled by factors such as local weather conditions, ecosystem dynamics, and management decisions, projecting the impacts of climate change on marine fish stocks is problematic. There is some chance that climate change will induce major ecosystem shifts in some areas that would result in radical changes in species composition with unknown consequences. Barring such shifts, moderate warming is likely to improve conditions for some important fish stocks such as cod and herring, as higher temperatures and reduced ice cover could possibly increase productivity of their prey and provide more extensive habitat.

Greenlandic Cod and Climate

A striking example of a positive climate-related impact involves West Greenland cod. Under the very cold conditions between around 1900 and 1920, there were few cod around Greenland. In 1922 and 1924, large numbers of cod were spawned in Icelandic waters and drifted from Iceland to East Greenland and then to West Greenland where they flourished, resulting in the start of a significant fishery beginning in the mid- to late 1920s. Large numbers of these cod returned to Iceland to spawn in the early 1930s and then remained there. However, many other cod stayed and spawned off West Greenland, giving rise to an independent, self-sustaining cod stock. During the warm period that spanned the middle of the 20th century, the Greenland cod stock grew very large, sustaining an annual average catch of about 315,000 tonnes between 1951 and 1970. The cold conditions that have prevailed since about 1965 appear to have rendered cod incapable of reproducing in Greenlandic waters. The only significant catches since then have been based on fish born in Icelandic waters in 1973 and 1983 that drifted to Greenland from Iceland.

While projected conditions are likely to benefit some species, such as cod, they are likely to negatively affect others, such as northern shrimp, necessitating adjustments in commercial fishery operations. The area inhabited by some arctic species, including northern shrimp, will probably contract and the abundance of those species decrease. This would reduce the large catch (about 100,000 tonnes a year) of northern shrimp currently taken from Greenlandic waters. Furthermore, northern shrimp are an important part of the diet of cod in the waters off Greenland. Thus, if the cod stock were to grow as it did in the last century, the decline in the northern shrimp population could negatively affect the diet and growth of the cod stock. Because the commercial value of a healthy cod stock would be much greater than the value of the shrimp catch, the shrimp fishery would have to be curtailed even further.

Climate, Overfishing, and Norwegian Herring

In the early 1950s, the stock of Norwegian spring-spawning herring was as large as 14 million tonnes, the world's largest herring stock, and was important to Norway, Iceland, Russia, and the Faroe Islands. At that time, these herring migrated west across the Norwegian Sea to feed in the zooplankton-rich waters north and east of Iceland as well as in the oceanic area between Iceland and the island of Jan Mayen (71°N, 8°W). In 1965, a sudden and severe cooling of these waters resulted in the decimation of the tiny crustacean (Calanus finmarchicus) that was by far the most important single food item in the diet of these herring. The herring’s feeding areas were displaced to the east and northeast by several hundred nautical miles, thus placing the stock under severe environmental stress. In the 1960s, the stock was also subjected to severe overfishing and collapsed during the latter half of the decade. Although high fishing intensity of both adults and juveniles was the primary reason for the collapse, the climatic cooling probably contributed to the decline.

In the 1970s, the small numbers of herring that were left did not need to search far to feed and thus stayed close to the Norwegian shore. What was left of the fishery was strictly regulated, and fishing was prohibited for several years. These restrictions, coupled with favorable climatic conditions, contributed to the stock's increase to three to four million tonnes and limited fishing began again. In 1995, the stock reached five million tonnes and extended its feeding grounds and migratory range into international waters. The stock therefore became available for fishing outside Norway's jurisdiction, making the Norwegian management regime insufficient to protect the stock and threatening its continued recovery. In 1996, an agreement was reached between Norway, Russia, Iceland, the Faroe Islands, and the European Union to set quotas for allowable catches of Norwegian spring spawning herring. Such agreements will be crucial in the future as climate change alters fish stocks and their ranges.

Climate Shifts and Fisheries Impacts

A climate shift occurred in the Bering Sea in 1977, abruptly changing from a cool to a warm period, perhaps a reflection of the Pacific Decadal Oscillation. The warming brought about ecosystem shifts that favored herring stocks and enhanced productivity for Pacific cod, skates, flatfish, and non-crustacean invertebrates. The species composition of living things on the ocean floor changed from being crab-dominated to a more diverse mix of starfish, sponges, and other life forms. Historically high commercial catches of Pacific salmon occurred. The Walleye pollock catch, which was at low levels in the 1960s and 1970s (two to six million tonnes), has increased to levels greater than ten million tonnes for most of the years since 1980.

For most of the North Atlantic, the total effect of climate change on arctic and sub-arctic fish stocks is likely to be of lesser magnitude than the effects of fisheries management, at least for the next two to three decades. This is mainly due to the relatively small warming expected for the first part of the 21st century in this area. In the Bering Sea, however, rapid climate change is already apparent, and its impacts significant. The Bering Sea is experiencing a major warming in bottom water temperature that is forcing cold-water species of fish and mammals northward and/or into decline. The first concern of Bering Sea fisheries management is thus likely to be managing for the ecosystem reorganization that is and will continue to be taking place as a result of climate change.

While it seems unlikely that climate change effects on fisheries will have long-term arctic- wide social and economic impacts, certain areas that are heavily dependent on fisheries are likely to be affected. Very severe dislocations are possible and have occurred historically. For example, when the Labrador/Newfoundland cod fishery collapsed due to overfishing, shifts in oceanic conditions, and other factors in the early 1990s, many cod fishermen went out of business or switched to other species, and the value of the fish catch in the province declined sharply. The cod stock has still not recovered, although a decade has passed. The shrimp and crab fisheries that eventually replaced the cod fishery are much less labor intensive and employ far fewer people, although the total commercial value of the fishery is about twice the value of the cod fishery. So while the fishing industry can generally adapt at the national level, particular people and places can be strongly affected.

Seal Hunting, Fishing, and Climate Change in West Greenland:  A Historical Perspective

Historical changes in West Greenland provide a good example of the relationship between climate change and associated social and economic changes. A climatic variation resulted in warming of the waters to the south and west of Greenland in the 1920s and 1930s, causing seal populations to shift northward, making seal hunting more difficult for the local Inuit. At the same time, cod (as well as halibut and shrimp) moved into the warmer waters, enabling the development of a cod fishery. Some local people, such as those in the west coast town of Sisimiut, were able to take advantage of the opportunities that arose due to social and technological factors. Sisimiut became an important fishing center with other new industries and a diverse economic base. This stands in contrast to the development of the southwest Greenlandic town of Paamiut around the same time. Paamiut’s development was based largely on plentiful resources of cod. With few other resources available in commercially viable quantities, there was little incentive to diversify the local economy. The concentration on a single resource made the town vulnerable to environmental change. When the cod population began to fall, due to a combination of climatic change and overfishing, the economy and population of Paamiut declined as a result. This points to the importance of recognizing in any adaptive strategy that local conditions (environmental, social, economic, technological, etc.) are important factors in determining the success of a region subject to change.