lale I96()"s, it went on to skirt Greenland and Labrador in the 

 direction of the North Atlantic current, reaching the Barents 

 Sea in 1979-80 (Dickson ('?«/., 1984). In the late I980"s.this 

 anomaly led to extremely low prevailing temperatures in the 

 waters off northern Iceland, which was probably the cause for 

 the drop in numbers of Atlantic-Scandinavian herring. 



The above changes in fish resources were brought about 

 by relatively short-term tluctuations in the temperature of the 

 environment. Proceeding on the assumption that global wanning 

 would entail a long-term upward creep t)f temperatures, this 

 factor may be expected to have even more profound effects on 

 the fish resources of the ocean. A rise in the mean temperature 

 of polar and subpolar waters of the World Ocean of just l°C 

 could have a substantial influence on the distribution, growth, 

 and replenishment offish populations. Commercially valuable 

 fish stocks may acquire new spawning grounds, which would 

 entail considerable changes in their distribution patterns. 



The strong homing instincts of salmonids in the Northern 

 Hemisphere would probably render changes in the geographic 

 distribution of these species to be fairly difficult. On the other 

 hand, salmonid populations may suffer considerable attrition 

 should geographic shifts of habitat become an absolute necessity 

 for thein. 



A more complete assessment of the effects of global 

 warming on the state of fish resources in the high latitudes of 

 the World Ocean requires allowance not only for temperature 

 rises, but also for increased hard ultraviolet radiation fluxes. 

 The latter factor would impact first and foremost upon those 

 fishes whose early developmental stages live either in neuston 

 communities or in coastal ecosystems. It must be borne in mind 

 that notwithstanding the relative opaqueness of seawater to 

 ultraviolet radiation, the roe and fry floating and swimming 

 near the surface, together with the accompanying phyto- and 

 zooplanklon, corals, and algae of tidal /ones, would be subjected 

 to prolonged and intense irradiation, which may well increase 

 the mortality of young fish and adversely affect the gene pool 

 of the marine organisms in question. 



Regional Aspects of the Problem (Using the Bering Sea as 

 an Example) 



Taking into account all of the foregoing, we would draw 

 particular attention to the extensive body of information 

 concerning the functioning of the Bering Sea ecosystem built 

 up in the course of long-term joint US-USSR studies (the 

 project entitled Comprehensive Analysis of the Bering Sea 

 Ecosystem , under the "Bering Sea" Program). 



According to predictions based on the use of GCM's, the 

 effect of global warming on the Bering Sea region could take 

 the fonri of a displacement of surface water isotherms toward 

 the North Pole (warming by 0.5°C over a single decade would 

 be accompanied by a shift in isotherms of over 30 km | Hansen 

 et ai, 19881 ). Temperature rises could lead to earlier vernal 



blooming of phytoplanktt)n and to a lengthening of the entire 

 blooming season. 



By present estiinates, primary production in the Bering 

 Sea averages 0.6.3 g C/m7day, attaining 7 g C/ni7day in some 

 places (McRoy&Goering, 1976; Izraelefa/., 1986;Whitledge 

 etai. 1988). The predicted advent ofconditions more conducive 

 to phytoplankton vegetation suggests increases of primary 

 production up to 0.75-0.90 g C/m'/day. 



Starting from a current rate of degradation of organic 

 matter in the Bering Sea that averages 0.3 g C/mVyear (Izrael 

 et ai. 1986; Whitledge et ai, 1988), global warming might 

 bring this value up to 0.35-0.50 g C/mVyear. 



The expected acceleration of microbiological and 

 photochemical processes would be accompanied by more 

 rapid decomposition of organic pollutants and, as a consequence, 

 by a reduction of levels of pollution of the given ecosystems by 

 human activities (Izrael et ai. 1990). 



An intensiflcation of production-degradation processes 

 could also result in the acceleration of biosedimentation 

 processes, especially in coastal areas. According the latest 

 experimental assessments based on determinations of organic- 

 matter biosedimentation rates (Izrael et al., 1986), 

 1.6 X 10' tons of C settle to the bottom of the Bering Sea 

 annually. On condition that the balanced character of the 

 biogeochemical carbon cycle is maintained, this value can be 

 taken as the lower limit for the influx of atmospheric carbon 

 into the waters of the Bering. It is relevant in the connection to 

 mention that the total contribution of carbon to the World 

 Ocean is 53 x 10'* tons/year (Odum, 1986). These figures 

 confirm the significance of subarctic ecosystems in the overall 

 context of the global carbon cycle and point up their major role 

 in shaping the Earth's climate. 



One of the inost significant consequences of global warming 

 may be the displacement of the subarctic front, which would 

 entail radical changes in the environment of pelagic and benthic 

 communities, including many valuable fish species. Since the 

 Bering Sea is a fishing area of enormous importance to a 

 number of countries that together catch 3 x lO*" tons of fish 

 annually (Wilimovsky, 1974), it is imperative to foresee possible 

 detrimental consequences of global warming in this region as 

 they impact upon the distribution and replenishment of many 

 valuable species offish, birds, and mammals. Elaboration of 

 prognoses of the state of living resources in the Bering Sea area 

 in conditions of global warming would greatly facilitate the 

 development of an effective system of adaptive responses for 

 this region. 



The long-term studies in the Bering and Chukchi Sea 

 conducted over the past decade will continue and will in future 

 encompass the issues discussed in the present paper within the 

 context of BERPAC. 



Efforts under BERPAC are part of the USSR's MONOK 

 program: The Integrated Ecological Ocean. 



11 



