BROWN ET AL : LINEAR PROGRAMMING SIMULATIONS 



Table 4. — Sum of individual country's linear programming 

 simulation of 1975 catches, maximizing total catch (1,000 1), and 

 using 1973 bycatch ratios for the ICNAF area. 



total using 1973 bycatch ratios, the rest being 

 taken as bycatch. The highest percentage of 

 TAC's, which were caught in directed fisheries, 

 were for other pelagics (9(K^), Atlantic herring 

 (797r), other groundfish (76%), and redfish (75%) 

 using 1971 bycatch ratios, and for Atlantic her- 

 ring (89% ), silver hake (87% ), Atlantic mackerel 

 (85%), and redfish (82%) using 1973 bycatch 

 ratios. 



Referring to the individual country linear pro- 

 gramming output tables in the Appendix, it is 

 obvious that under 1971 and 1973 bycatch ratios, 

 national patterns ran the gamut from almost a 

 total mixed fishery by the U.S.S.R., and to a some- 

 what lesser extent by the G.D.R., to very specific 

 fisheries of the F.R.G. and Poland. 



As noted earlier, the species which was most 

 frequently limiting to the total reported 1975 



catch was Atlantic herring (6 out of 11 countries), 

 and the countries which had the most limiting 

 species TAC's were United States (5) and U.S.S.R. 

 (4). Except for the catches of U.S.S.R., United 

 States, G.D.R., and Poland, there was little differ- 

 ence in reported total catch minus simulated re- 

 ported catch, when 1971 and 1973 bycatch ratios 

 were used. Moreover, only for U.S.S.R were these 

 differences > 50,000 t, and for six of the countries 

 the differences were < 10,000 t for both schemes. 

 The species for which the simulated and reported 

 total catches differed most varied by country. At- 

 lantic herring and Atlantic mackerel were the 

 species most frequently differing in simulated vs. 

 reported catches, but Atlantic mackerel and silver 

 hake contributed most in metric tons to the differ- 

 ences. In general, and in view of the findings of 

 Brennan ( 1975), the differences between schemes 

 using 1971 and 1973 bycatch ratios were minimal, 

 and more likely due to the different grouping of 

 the data. 



A summary of the 1975 TAC's, the 1975 re- 

 ported catches, and the linear program estimates 

 of total catch by country, is presented in Table 5. It 

 is obvious that the overall TAG of 850,000 t for 

 1975 would not be attained without exceeding cer- 

 tain species TAC's unless bycatch was reduced, 

 according to the simulations. The expected catches 

 of 626,750 t using 1973 bycatch ratios and of 

 681,050 t using 1971 bycatch ratios are only 74% 

 and 80% , respectively, of the 1975 total TAG On a 

 country basis, and using the results derived from 

 the 1973 bycatches, it can be seen that the country 

 total TAC's were set for 1975 at approximately 

 appropriate levels for France and Spain (based on 



Table 5. — Comparison of linear programming estimates of maximum total catch by overall country's total allowable catches (TAC's) 



in the ICNAF area. Figures in 1,000 t. 



'No estimate available. 



^Six thousand metric tons of other species not prorated to other species. 



^Includes 2,000 t allocated to others. 



"Due to the absence of bycatch ratios for 1971 data, estimate of France's total catch is derived from the 1973 bycatch ratios. 



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