High-latitude marine fisheries are very productive. For example, those in the northern Pacific Ocean and the Bering Sea contribute more than 28% to total world landings of fish, mollusks, and crustaceans. In some northern countries, fisheries and fish products account for a large proportion of gross domestic product. In Greenland, the shrimp industry contributed more than 30% to GDP in 1986. Landings of fish in the Northwest Territories and in Nunavut, in the commercial and the subsistence sectors of the economy, are valued at CDN$12 million.
Shifts in oceanic circulation associated with global warming are likely to affect the distribution of commercially important fish and their migration routes (Buch et al., 1994; Vilhjalmsson, 1997). For example, the first catches of two species of Pacific salmon (Oncorhnchus nerka, O. gorbuscha) recently have been made in estuaries on Banks Island, Canada. These locations are well outside the known range for these Pacific species (Babaluk et al., 2000). Changes in ocean currents, nutrient availability, salinity, and the temperature of ocean waters can be expected to influence the disposition of larval and juvenile organisms, the growth rates of individuals, and the population structure of different fish species (Otterson and Loeng, 2000). For example, recruitment appears to be significantly better in warm years (Loeng, 1989), an example of which is increased landings of cod (Gadus morhua) associated with warmer air and surface water temperatures (Brander, 1996). During a warm phase between the 1920s and the 1960s, Norwegian herring fed in Icelandic waters but disappeared when the water temperature cooled by 1°C (Vilhjalmsson, 1997). Quinn and Marshall (1989) report positive correlations between salmon returns and reduced sea ice. However, species that are adapted to cold water, such as the Greenland turbot and the Alaskan King crab, declined in numbers during these warm phases, although other factors also contributed to the decline of crab stocks (Weller and Lange, 1999). However, the underlying mechanisms that account for changes in population sizes are poorly understood. This topic is a high research priority, particularly because plankton production and trophic interactions may be significantly altered by changes in climate. Research and management advice for fish stocks is provided by the International Council for the Exploration of the Seas (ICES). This authority and others face formidable challenges if the distributions of fish populations change in response to global warming (Hønneland et al., 1999; Freese, 2000).
Husbandry of different subspecies of Rangifer tarandus is widely practiced in different regions of the Arctic, particularly in Eurasia. Between 1991 and 1997, Russia's domestic reindeer stock declined from 2.3 million to 1.6 million animals. Whether climate change contributed to this decline is uncertain (Weller and Lange, 1999), but climate warming is likely to alter husdandry practices. Concerns include the presence of deep snow with an ice surface that stops animals from obtaining forage, lichens and graminoids that are ice-covered, destruction of vegetation as a result of "overgrazing," exposure of soil that encourages establishment of southerly weedy species under a warmer climate (Vilchek, 1997), and an increased likelihood of damage from more frequent tundra fires.
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