Ecological interactions did play a role to some extent 

 in the selection of OY levels. The rationale was qualitative 

 in nature, however, and rested on the assumption that the 

 average anchovy density expected in association with the pro- 

 posed fishing regime has not in the past been associated with 

 any observed decline in predator populations such as marine 

 mammals. While that assumption cannot be discounted on the 

 basis of available evidence for the 1950-1960 period, it can- 

 not be supported by that evidence eitner. 



Some quantitative analysis of the impact of proposed 

 fishing levels on the forage available to predators would 

 have been possible based on the data provided in the plan. 

 In the northern anchovy section of Appendix F, an example cal- 

 culation of changes in forage availability is presented. The 

 example is based on estimated rates for natural mortality, 

 fishing mortality and somatic growth rate for the population 

 presented in the plan, as well as on estimates of the expected 

 median annual abundance for anchovies under the proposed OY 

 regime. The example uses standard fishery calculations of 

 natural mortality given the population growth rate assumptions , 

 but interprets the calculations in a new way. The long term 

 reduction in anchovy consumption by predators with the pro- 

 posed OY catch of several hundred thousand tons per year is 

 estimated in the example in Appendix F to be on the order of 

 1.2 million tons per year, half of the predation on ancho- 

 vies in the absence of a fishery, or one quarter of total 

 forage fish consumption. The impacts of such a large change 

 in food availability on ecosystem carrying capacity and pre- 

 dator populations, the availability of alternate prey re- 

 sources, and the impacts on those alternate prey of increased 

 predation were not discussed in the plan. While the per- 

 formance of the calculations in Appendix F demonstrates that 

 such a quantitative analysis would have been possible given 

 information provided in the plan, no rough quantitative eval- 

 uation of the impact of proposed harvest levels on anchovy 

 predators was attempted in the plan. 



The Northern Anchovy Plan dealt with an endangered spe- 

 cies, the California brown pelican. However, the recommenda- 

 tion of monitoring of pelican populations appears to be equiv- 

 alent to a "wait and see" attitude toward the pelican, par- 

 ticularly since the council itself will not be responsible 

 for monitoring the pelican populations. In effect, the treat- 

 ment of pelican populations in the plan would seem to require 

 that an adverse impact on pelican populations will have to 

 be demonstrated before any action on OY would be taken to 

 mitigate such an adverse impact. The ESA requires that fede- 

 ral agencies ensure that actions authorized by them do not 



36 



