Trap‐based indicators of egg production following increases in minimum legal size in Homarus americanus fisheries

Abstract

Minimum legal size (MLS) is an important conservation measure in trap fisheries for Homarus americanus. MLS has increased in several management areas in the Canadian Maritimes since 1987. A key conservation objective has been to increase egg production, with predictions of the effects of MLS increase based on egg‐per‐recruit models. We evaluated whether expectations of increases in ovigerous females (OF) were realised when MLS was increased. Data were examined from at‐sea samples of the commercial trap catch from 11 ports from 1986 to 2003. OF indicators were developed based on the OF catch‐per‐unit‐effort (CPUE) of different sizes, and on the percentage (PCT) of females that were ovigerous. Because there were within‐season increases in CPUE and PCT, annual indicators were based on regressions of CPUE on day in the season. There was considerable variability in all the time series of OF annual indicators and any effects of smaller MLS increases could not be detected. Increases in OF indicators were evident in areas that undertook the largest MLS increases (6–6.5 mm CL).