3. When the estimated spawning biomass is 1 million 

 tons or greater, OY for the combined reduction 

 and non-reduction fishery is 18,000 tons or 1/3 

 of the biomass in excess of 1 million tons , which- 

 ever is greater. 



Under this formula, OY at a biomass of 1.8 million tons 

 spawning biomass would be 267,000 tons, considerably less 

 than the MSY figure of 484,000 tons of the same biomass. 

 In contrast, OY for a spawning biomass of 3.6 million tons, 

 the estimated population for 1976, would be 870,000 tons, 

 much greater than the 1976 harvest of about 200,000 tons. 



The OY formula is expected to reduce the impact of ex- 

 ploitation when anchovy biomass is low, and to protect the 

 long-term productivity of the resource. The plan concludes 

 that a long-term average anchovy biomass in excess of 2 mil- 

 ion tons should not have a severe adverse impact on preda- 

 tors. Under the OY formula determined in the plan, spawn- 

 ing biomass is anticipated to fluctuate around an average 

 of 2.5 million tons. 



Bering Sea Groundfish Draft Plan, 1978 



The North Pacific Council's Draft Bering Sea Groundfish 

 Plan covers many species, including Alaska pollock, yellow- 

 fin sole, turbot, other flatfish, Pacific cod, rockfish 

 including Pacific ocean perch, sable fish, Atka mackerel, 

 squid and others. The plan, in fact, covers all groundfish 

 except herring and Pacific halibut. The plan includes as 

 an objective designing fishing strategy to minimize effects 

 on other fisheries and on the environment. 



The Bering Sea has some very productive waters and con- 

 sequently high densities of fish, marine mammals and birds. 

 Fish fauna are dominated by pollock. A computer simulation 

 model, DYNUMES III (Dynamic Numerical Marine Ecosystem Model) 

 has been developed for the fish of this region (Laevastu and 

 Favorite, 1978). The DYNUMES model considers growth, re- 

 cruitment or production, and mortality of individual fish 

 species or groups of species. The model also considers pre- 

 dation on groundfish by marine mammals, birds, and other fish. 

 In the plan, fish consumption by predators is estimated to 

 be 5 : 8 million metric tons on the basis of the DYNUMES model. 

 However, no estimates were made of changes in the availa- 

 bility of food to predators which might be associated with 

 various proposed fishing levels in the plan, even though 

 the DYNUMES model uses information on which such estimates 

 could have been based. 



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