FISHERY BULLETIN: VOL 74, NO. 1 



catches taken at varying distances from shore, 

 were not available to examine this possibility in 

 detail. However, Messersmith et al. (1969) re- 

 ported that, during summer and fall echo-sounder 

 surveys, all sizes of anchovies were found concen- 

 trated close inshore. Since all sizes were encoun- 

 tered, we speculated that, if fishing were allowed 

 inside of 3 miles (4.8 km), the catchability coef- 

 ficient for older fish would become reduced only if 

 effort concentrated on or very near nursery 

 grounds, which occur on shallows and flats inside 

 of 50 fathoms. Although lower fuel costs might 

 dictate such a concentration, we further specu- 

 lated that enforcement of the current minimum 

 size limit of 10.8 cm would make fishing this far 

 inshore unattractive and thus curtail it. 



Given these speculations, simulation experi- 

 ments were conducted in our first application to 

 examine the biological and economic conse- 

 quences of opening the inshore area to commer- 

 cial fishing and of allowing a 12-mo fishing 

 season. These were contrasted to a "present" sit- 

 uation consisting of a closed inshore area and an 

 8-mo season (15 September-15 May). Moreover, 

 sensitivity of the model to changes in the stock- 

 recruit relationship was examined given alterna- 

 tive areal-seasonal restrictions. Stock-recruit 

 curve 2 (Table 8) was arbitrarily chosen as the 

 standard for comparison in these experiments. 

 Each experiment thus determined how an opti- 

 mal harvesting-processing configuration (num- 

 bers of vessels and plants) defined for curve 2 per- 

 formed when stock-recruit curve 1 or 3 were in 

 effect. Essentially, then, each experiment simu- 

 lated the decision-making problem wherein a 

 manager assumes that a given biological situa- 

 tion is "true" and plans to meet it but then en- 

 counters a completely different situation. 



The results of this first group of sensitivity ex- 

 periments are indicated in Table 10. The main 

 criteria for comparing performances under differ- 

 ent stock-recruit curves are the absolute and per- 

 centage differences in net economic returns indi- 

 cated in the last two columns of this table. In all 

 cases, relative to curve 2, harvesting-processing 

 systems performed better under curve 1 and 

 worse under curve 3. As seen from the larger re- 

 turns, catches, and biomasses generated and from 

 the fewer days of fishing required, curve 1 defined 

 a more productive biological regime relative to 

 curve 2. Likewise, from the smaller returns, 

 catches, and biomasses and from the generally 

 greater number of days of fishing required, curve 

 3 defined a less productive biological regime. 



The economic consequences of imposing differ- 

 ent regulatory schemes can also be determined 

 from Table 10. Opening the inshore area would 

 generate about a 30^ improvement in net return. 

 Given our assumptions, such an increase is likely 

 due to the increased availability of O's and I's 

 which in turn leads to greater catches for the 

 same level of effort. On the other hand, a change 

 in season length would generate an improvement 

 in returns of 120-130%. Quite obviously, from 

 an economic viewpoint, the model indicates that 

 the preferable management scheme would be 

 a change to the 12-mo season. Barring that, 

 the next best scheme would be to open the in- 

 shore area. 



However, these economic findings should be 

 tempered somewhat by sensitivity considera- 

 tions. Comparison of areas within seasons (Table 

 10) reveals that an open inshore area is less sen- 

 sitive to changes in stock-recruit relations than is 

 a closed inshore area. That is, the percentage 

 change in net returns is less for both curves 1 and 



Table lO. — Sensitivity of optimal configurations to changes in stock-recruit curves and areal 

 restrictions, given M = 1.10 and deterministic availability. 



'Situations used as standards for comparative purposes. 



126 



