FISHERY BULLETIN: VOL. 83, NO. 2 



(R-F-E/W) and the egg and larval mortality rates 

 through the function g {a, 13, tj) remain constant 

 from year to year It is clear that from 1951 to 1982 

 time series (Table 3) that the assumption of 

 constant egg and larval mortality has not been 

 met by the central California anchovy population. 

 The HEP requires constant reproductive output. 

 The validity of this assumption can only be tested 

 with future data. 



In addition to the ichthyoplankton data, several 

 other indices of anchovy biomass exist: acoustic 

 trawl surveys conducted by California Depart- 

 ment of Fish and Game, aerial survey records from 

 aircraft associated with the fishery, catch-effort 

 analysis (CPUE), and cohort analysis from the 

 catch of the United States and Mexican fishery. In 

 a recent management plan, all of these indices 

 except cohort analysis have been calculated and 

 compared with the time series of egg production 

 presented in this paper (MacCall et al.^). The 

 estimates of egg production covaried with these 

 other indices from year to year and appeared to be 

 the most consistent index of spawning biomass 

 among these indices (Table 5). 



Selection of the appropriate method for esti- 

 mating biomass depends upon the data availabil- 

 ity and knowledge of the growth of eggs and 

 larvae. If nothing is known of the age of eggs and 

 larvae and no information exists on reproductive 

 parameters, the LCE is the only method available 



'MacCall, A. D., R. D. Methot, D. D. Huppert, H. W. Frey, and 

 O. Mathisen. 1983. Northern anchovy second draft revised 



fishery management plan incorporating DEIS/RIR. 

 Manage. Counc. 



Pac. Fish. 



Table 5. — Correlations among various indices of an- 

 chovy spawning biomass. Upper value is correlation 

 coefficient, lower value is number of observations. (Repro- 

 duced from table 4.3-2 of MacCall et al. (text footnote 9). ) 



'Consistency is average of correlation coefficients. 



although subject to major biases. If egg and larval 

 age data exist but no data on reproductive param- 

 eters are available, then the HEP is the preferable 

 method. The EPM is the best method; it requires 

 not only knowledge of egg mortality but accurate 

 estimates of adult reproductive parameters as 

 well. In many time series, both growth and abun- 

 dance of eggs and larvae are available but repro- 

 ductive parameters are not. In these cases, the 

 HEP is probably the most accurate means of 

 creating a historic time series of biomass. 



ACKNOWLEDGMENTS 



I thank John Hunter, Roger Hewitt, Paul 

 Smith, Rick Methot, Alec MacCall, Jay Barlow, 

 National Marine Fisheries Service; David Farris, 

 San Diego State University; Grace Yang, Uni- 

 versity of Maryland; two referees for reviewing 

 the manuscript and making valuable suggestions. 

 I also thank Barry Finzel, Cynthia Meyer, Carol 

 Miller, and Richard Charter for compiling his- 

 torical egg and larval data files, and Mary DeWitt 

 and Debra BrowTi for typing the manuscript. 



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