http://worldcat.org/entity/work/id/10438477

Biological reference points for anadromous alewife (Alosa pseudoharengus) fisheries in the Maritime Provinces

This report analyzes the population dynamics of four anadromous alewife populations in the Maritime Provinces to evaluate reference points for the management of alewife fisheries. These reference points are based on the biological characteristics of a fish stock and are used to gauge whether specific management objectives are being achieved. The first section uses a statistical, life-history-based assessment models to produce spawner-recruit time series and estimate maturity schedules, exploitation rates, and natural mortality for the populations studied. The second section estimates reference points for the alewife populations using yield per recruit, spawning biomass per recruit, and production models. In the third section, a simulation model is employed to evaluate the relationship between target fishing mortality rates and the performance of the fisheries when stochastic variability is added to the recruitment process. In addition, it compares simulations with stochastic variability in the maturity schedule with simulations using constant maturity schedules to determine whether failure to consider variability in age at maturity can lead to over-exploitation of these stocks.

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