Long-term effects of marine reserve protection on the population structure, density, and reproductive potential of the American lobster (Homarus americanus) in Bonavista Bay, Newfoundland

Collins, Roanne K. (Roanne Kyla). (2010) Long-term effects of marine reserve protection on the population structure, density, and reproductive potential of the American lobster (Homarus americanus) in Bonavista Bay, Newfoundland. Masters thesis, Memorial University of Newfoundland.

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Abstract

Marine reserves provide a means of implementing the precautionary principle in support of sustainability objectives. Many reserves have been established for several commercially significant species of spiny lobster, but are less frequently employed for Homarid lobsters. In 1997, two small reserves for American lobster, Homarus americanus, were established in Bonavista Bay, Newfoundland - one at Round Island, and one at Duck Islands. They were designated as Marine Protected Areas (MPAs) in 2005. Relatively short-term studies, employing 3 to 5 years of data, revealed significant differences in lobster density and/or mean size between populations within the reserves and similar reference locations, but did not examine differences in reproductive output. Using over ten years of data, I investigated differences in density, population structure (i.e. size; sex ratios), and reproductive potential between protected and unprotected populations of American lobster at both study sites. At the Round Island site, lobster density inside the reserve was greater than that of the adjacent reference area. Observed sex ratios in reserve and reference locations differed at both sites, with a greater bias towards females in reference locations. At Round Island and Duck Islands study sites, both male and female lobsters were significantly larger in protected populations, and mean sizes continued to increase over time. The increased female size in protected populations led to consistently greater reproductive potential inside these reserves, though the difference between protected and unprotected populations was small, averaging 10% for Round Island and 14% for Duck Islands. The results of this study provide further evidence that the Eastport MP As promote sustainability of the resource through increased density, mean size and reproductive potential of lobsters.

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