FISHERY BULLETIN: VOL. 75, NO. 1 



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PACIFIC SARDINE 



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ATLANTIC MENHADEN 



55 

 % 



-'56 



FIGURE 8. — Year-class size related to 

 spawning stock size and linked in 

 chronological order for Atlantic 

 menhaden and Pacific sardine. Pacific 

 sardine figure after Radovich 

 (1962:134). 





SPAWNING STOCK SIZE (BILLIONS OF FISH) 



SIZE OF SPAWNING STOCK |NO OF EGGS * 10"l 



menhaden fishery, given high fishing effort and 

 additional years of poor survival, cannot be dis- 

 counted. 



Fortunately, there are significant differences in 

 the environment, biology, and fishery of Pacific 

 sardine and Atlantic menhaden. One of the more 

 important differences is the estuarine depen- 

 dence of menhaden. In every year, at least some 

 estuarine systems on the east coast should 

 provide favorable environments, insuring good 

 survival of larvae which reach those nursery 

 grounds. Also, spawning activities spread over the 

 entire coast should include at least some areas 

 conducive to survival, reducing the chance of 

 almost no survival over the entire range. Climatic 

 change which shifts the distribution of menhaden 

 spawning activities would not likely shift the 

 spawning region far enough away from suitable 

 nursery areas to cause the type of massive failure 

 that occurred in the sardine fishery. Another 

 significant factor in the collapse of the sardine 

 stocks was an increase in the stock size of compet- 

 ing species, filling the niche in the ecosystem as 

 the sardine population decreased. Although there 

 is no fishery for species which are potentially 

 competitive with Atlantic menhaden and 

 adequate stock data on such species are not av- 

 ailable, there are no indications of large increases 

 in abundance of any coastal pelagic species, and 

 the niche available to menhaden appears to be 

 open. However, John Radovich (pers. commun., 

 California Department of Fish and Game) points 

 out that "the value of not having identified an 

 increase in competitors for the menhaden may be 

 of little significance because: 



1) The sardine collapse and failure to recover 

 may have happened without a 'competing' 

 species such as the anchovy. 



2) Available forage and habitat may be utilized 

 through slight increases in the abundance of 

 several species, and hence go unnoticed. 



3) The capacity within a trophic level may vary 

 considerably so that actual changes in the 

 abundance of competing species may be 

 masked by changes in available forage and 

 habitat." 



The menhaden fishery is somewhat self- 

 regulating, in that low stock levels have brought 

 about economic conditions which forced a reduc- 

 tion in effort and closure of processing plants. The 

 closure of plants in the northeast United States 

 during the late 1960's reduced fishing effort on 

 older age-groups, halting the drastic decline in 

 spawning stock size (Schaaf in press). This action, 

 plus good survival in 1966 which produced the 

 spawning stock for the high transport, large year- 

 class year of 1969, is probably responsible for the 

 brief resurgence of the fishery in the early 1970's. 



Implications for the Fishery 



Implications for the fishery are rather 

 straightforward: in years of poor environmental 

 conditions recruitment is low regardless of stock 

 size; extremely low spawning stock sizes in years 

 of poor environmental conditions result in re- 

 cruitment below the level needed to maintain the 

 fishery; favorable environmental years will 



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