. The Eastern Bering Sea Shelf : oceanography and resources / edited by Donald W. Hood and John A. Calder. Oceanography Bering 612 Fisheries oceanography A. Processes affecting biomass abundance Main process SPAWNING (reproduction, larval recruitment) GROWTH PREDATION (mortality) MORTALITIES â (SPAWNING) Processes affecting biomass distribution SOURCE-SINK AREAS (Differences in abundance affecting factors in space and time) MIGRATIONS Seasonal Life cycle dependent Environment dependent Major affecting factors Spawning biomass size (including fecundity) Predation on eggs and larvae Av
. The Eastern Bering Sea Shelf : oceanography and resources / edited by Donald W. Hood and John A. Calder. Oceanography Bering 612 Fisheries oceanography A. Processes affecting biomass abundance Main process SPAWNING (reproduction, larval recruitment) GROWTH PREDATION (mortality) MORTALITIES â (SPAWNING) Processes affecting biomass distribution SOURCE-SINK AREAS (Differences in abundance affecting factors in space and time) MIGRATIONS Seasonal Life cycle dependent Environment dependent Major affecting factors Spawning biomass size (including fecundity) Predation on eggs and larvae Availability of food (including starvation) Environmental factors (including advection) Age Temperature (anomalies) Food availability Vulnerability (sp. size) Predator abundance Senescent mortality Spawning stress mortality Disease mortality Growth Predation Other mortalities Feeding migration Search for optimum environment Spawning migrations Predation avoidance migrations Feeding migrations Search for optimum environment Advection by currents (APEX PREDATORS AND FISHERY) Figure 37-1. Major dynamic processes in the marine ecosystem. Predation has been included traditionally in the all- encompassing term "natural mortality," of which pre- dation constitutes the major portion in most species. In order to remedy this shortcoming the predation mortality is computed within ecosystem models in great detail, using data on food requirements for growth and maintenance and space- and time-variable food composition. Very few fish stomach analysis studies have been accomplished on Bering Sea stocks. Those available usually list only the frequency of occurrence of food items in the stomach, making these studies of little quantitative value. Fortunately recent European studies of fish feeding habits (, Daan 1973) have established that feeding in the marine environment is largely dependent on the size of the fish and the size and availability of the food; this knowledge has been
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