Estimability of natural mortality and other population parameters in a length-based model: Pandalus borealis in Kachemak Bay, Alaska

• Published in: Canadian Journal of Fisheries and Aquatic Sciences
• Main Authors: Fu, Caihong, Quinn II, Terrance J
• Format: Article in Journal/Newspaper
• Language: English
• Published: Canadian Science Publishing 2000
• Subjects: Aquatic Science; Ecology, Evolution, Behavior and Systematics; Kachemak; Pandalus borealis; Alaska
• Online Access: http://dx.doi.org/10.1139/f00-220; http://www.nrcresearchpress.com/doi/pdf/10.1139/f00-220

Because stock-assessment models have become more complex, the question of estimability of population parameters is important. We conducted simulation-estimation experiments with a length-based model of the pink shrimp (Pandalus borealis Krøyer) population in Kachemak Bay, Alaska, to compare the robustness of various modeling approaches to specifications of natural mortality (M), catchability (q), a survey gear selectivity parameter (L 50 ), and data imprecision. Our goal was to determine the estimability of various parameters, particularly M, q, and L 50 . Simulation results suggest that interannual variations in M and L 50 could be estimated, if the underlying values have a trend over time. However, parameter q should be fixed at a chosen value, even when it varies over time. Estimated M for the Kachemak Bay P. borealis population increased in the 1980s, perhaps owing to increased predation mortality by groundfish.