NICHOLSON: ATLANTIC MENHADEN PURSE-SEINE FISHERY 



Table 12. — Mean catch per purse-seine set of Atlantic menhadpn, in metric tons, by year, month, and area. 



means are weighted, column means are unweighted. 



Row 



enough to reflect real differences in population 

 abundance. 



Variations in year-class strength have con- 

 tributed to fluctuations in population abundance. 

 Estimates of year-class strength prior to 1952 

 have been based on catch-per-unit-of effort fig- 

 ures and since 1952 on catch samples. From 

 1950 to 1958 there were four exceptionally large 



year classes, the largest occurring in 1958 (June 

 and Reintjes, 1959; Nicholson and Higham, 

 1964) . Most of the year classes after 1958 have 

 been smaller than any of the year classes prior 

 to 1958. This series of small year classes oc- 

 curred simultaneously with the general decline 

 in abundance, which began about 1956 and be- 

 came more noticeable in 1963, after the large 



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