AN INVESTIGATION OF THE POPULATION-DYNAMICS OF ATLANTIC MENHADEN (BREVOORTIA-TYRANNUS)
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abstract
A hypothesis of density-dependent growth is strongly supported by the data and that the dependence of growth on abundance appears to occur prior to recruitment. Age-specific natural mortality estimates seem biologically reasonable, except the estimate for age 1 menhaden, which appears to be too low. Most of the estimated migration probabilities also seem to be biologically reasonable, especially during the summer season for age 2 fish. Estimated age-specific fishing mortality rates demonstrate the increased fishing pressure on age 3 and younger fish since the early 1960s. When the environmental variables (temperature and Ekman transport) are excluded from the spawner-recruit analysis, the Beverton-Holt model fits as well as other models examined, and it is the only model that is significant at the 0.05 probability level. Of the environmental variables examined, only westward Ekman transport in the South Atlantic region shows a relationship with recruitment. -from Authors
