Aspects of the life history of the Atlantic silverside (Menidia menidia) of the Annapolis River, Nova Scotia / B.M. Jessop.: Fs97-4/1694E-PDF

"Aspects of the life history of the Atlantic silverside, Menidia menidia, including seasonal distribution, age structure, sex ratio, growth rate, maturation and fecundity, were studied in the stratified, tidally restricted estuary of the Annapolis River, Nova Scotia. Adult silversides migrated into the estuary in April and May, spawned mainly in June and returned to sea between July and October. During spawning, adults were most abundant in the middle reaches of the estuary. Annapolis River silversides, which are near the northern limit of their range, have a greater proportion of Age-2 fish than do more southern populations. In all age groups, females are about twice as abundant as males. As a consequence of the shorter northern growing season, juveniles average smaller than do more southern populations, in spite of their faster growth rate. Maximum adult lengths are similar throughout the species range, but southern fish are Age 1 while northern fish reach Age 2. Females grew faster and lived longer than males, thereby attaining larger maximum sizes. Estimates of the von Bertalanffy growth-function parameters L ͚, K and tₒ for males were, 122.2 mm, 1.00 and -0.348; and for females, 128.2 mm, 1.04 and -0.305. A seasonal growth curve was more realistic and fitted the data better. The instantaneous rate of natural mortality (M) was similar (1.3) for both sexes. Sexual maturation and spawning first occur at Age 1. Fecundity increased with fish length, weight and age, ranging from about 700 to 3,100 ova/female. Age-2 females make an important contribution to population fertility. Insights into the life history of Atlantic silversides and the consequences for fishery management can be gained by viewing the species in terms of r- and K-selection theory. Silversides are typical r-strategists"--Abstract, page ix.

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publications.gc.ca/pub?id=9.951344&sl=0

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