. The Eastern Bering Sea Shelf : oceanography and resources / edited by Donald W. Hood and John A. Calder. Oceanography Bering Ecosystem dynamics 617 function of the relation between equilibrium biomass and actual biomass (, as conventionally assumed that large spawning biomasses produce proportionally smaller recruitment and vice versa) is shown in Fig. 37-6. The interactions of the biomass fluctuations are rather complex and would take too much space to analyze here, but computer printouts are available for this study. It should, however, be pointed out that there are "natural
. The Eastern Bering Sea Shelf : oceanography and resources / edited by Donald W. Hood and John A. Calder. Oceanography Bering Ecosystem dynamics 617 function of the relation between equilibrium biomass and actual biomass (, as conventionally assumed that large spawning biomasses produce proportionally smaller recruitment and vice versa) is shown in Fig. 37-6. The interactions of the biomass fluctuations are rather complex and would take too much space to analyze here, but computer printouts are available for this study. It should, however, be pointed out that there are "natural," quasiperiodic fluctuations of biomasses of considerable magnitude in the marine ecosystem. The period can be from a few yeeirs to more than a few decades and the magnitude can be considerable (, the biomass can be a fraction of a few tenths to several times its long-term mean value). These fluctuations can have manifold causes in addition to man (fishing). They can, to a certain extent, be studied with ecosystem -4 L Yellowfin sole Atka mackerel Pollock Herring Figure 37-6. "Natural" changes of biomasses of yellowfin sole, Atka mackerel, pollock, and herring in the fisheries management Area 1 in the eastern Bering Sea. SEASONAL DYNAMICS OF THE BERING SEA ECOSYSTEM There are two basically different causes of seasonal spatial and temporal changes in the biomasses. The changes in abundance are caused by seasonally changing growth, predation (and other causes of mortality), and production and release of eggs and milt; the changes in distribution are caused by sea- sonal migrations of species and environmental inter- actions. The results of both major causes of seasonal dynamics must be viewed spatially. Unfortunately, little consideration has been given to the spatial aspects of biomass (and ecosystem) dynamics in the past, mainly because of difficulties in empirical study by nonsynoptic resource surveys. However, the gridded ecosystem models with spa
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