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Age, growth and maturity studies on the Pacific anchovy (Engraulis mordax) from the coast of British Columbia Pike, Gordon Chesley

Abstract

The Pacific anchovy, Engraulis mordax Girard, occurs in limited numbers in most of the bays and inlets of southern British Columbia where it supports a small purse-seine fishery during the spring and summer months. A study of the age, growth and maturity of this species was carried out by the analysis of samples randomly selected from commercial catches during the years 1947 to 1951. Age and growth studies are based chiefly on the analysis of length frequency distributions and checked by scale readings. The use of length frequencies was facilitated by the presence of one or two dominant year classes in each commercial catch. The reliability of the method is supported by scale readings. Average lengths of 107, 128, 140, 149, and 157 millimetres are calculated for females at 1, 2, 3, 4, and 5 years; and average lengths of 105, 126, 138, 146 and 153 millimetres for males at the same ages. Maximum size of females is found to be 168 millimetres, representing an age of 7 years. Maximum size of males is found to be 153 millimetres, representing an age of 6 years. The incoming year class majority of fish taken in the commercial catches are 2 or 3 years of age. Maturity studies based on measurements of ova diameters show that spawning occurs in most of the bays and inlets in southern British Columbia in late June, July and August, The majority of females mature in their second year, but some may mature in their first year. The situation for males appears to be similar. Growth of the ova begins in adult females of all sizes and from all localities in February and March. By June the majority of females have matured three size groups of eggs preparatory to spawning. Evidence is given that multiple spawnings occur and that each of these size groups of eggs is matured and in turn spawned. No maturing ova are carried over into succeeding years. A minimum average of 144,000 eggs are spawned in three or more batches each year.

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