Size, structure, movement, and survival of American lobster, Homarus americanus, populations in areas with and without commercial harvesting

Rowe, Sherrylynn (2000) Size, structure, movement, and survival of American lobster, Homarus americanus, populations in areas with and without commercial harvesting. Masters thesis, Memorial University of Newfoundland.

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Abstract

To determine the potential effectiveness of no-take reserves as a fisheries conservation tool for American lobsters (Homarus americanus), I quantified the size, structure, movement, and survival of lobsters inside and outside of two small no-take reserves (Round Island and Duck Islands) in Bonavista Bay, Newfoundland during 1997-1999. These no-take reserves were established by harvesters as part of a co-management plan for the local fishery and supported approximately 1.5% of the local lobster population. Although this study only concerned the first three years following reserve establishment, there were clear differences in lobster population parameters inside and outside of the no-take reserves. At the Round Island reserve, population density was high and stable over time, and female and male size increased, as did the proportion of ovigerous females. However, at the Duck Islands reserve, population density increased dramatically between 1997 and 1998, and male size increased over time, but there was no detectable change in female size or in the proportion of ovigerous females. Lobster density, female and male size, and the proportion of ovigerous females were greater within the Round Island reserve compared to an adjacent harvested area. At the Duck Islands, females and males were larger in size within the reserve but I found no difference in lobster density or the proportion of females that were ovigerous between the reserve and an adjacent harvested area. Differences in the response of some lobster population components to small no-take reserves can be explained by patterns of lobster movement and survival. Because the frequency of lobster emigration from the reserves was low (only 8.7% of tagged lobsters recaptured were in an area with a harvesting status different from that of where they were tagged) and harvesting pressure outside of the reserves was intense (annual harvesting mortality amounted up to 87.2% for lobsters eligible for commercial harvest), my results indicated that no-take reserves can offer increased survival to lobsters and may provide direct benefits to the local fishery.

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