Population Assessments of Exploited Species at the Glover's Reef Marine Reserve, Belize

Acosta, Charles A. and Robertson, Denice N. (2001) Population Assessments of Exploited Species at the Glover's Reef Marine Reserve, Belize. Technical Report.

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    Abstract

    Marine Reserves that are closed to commercial fishing are now widely used as an essential tool for preventing overfishing and localized extinctions of exploited species in coastal environments. Reserves that function as harvest refuges for commercially valuable species have the potential to protect, sustain and even increase fishery productivity. Benefits that are expected to occur include larger population size, increases in average size of individual animals, increases in reproductive output of eggs and larvae and dispersal ("spillover") of animals from the protected area into fishing area after density increases in the harvest refuge. Because many exploited species are often keystone species that play important roles in coastal ecosystems, they may serve as "umbrella species" for the conservation of marine biodiversity and sensitive habitats. Given the multifaceted importance of protecting target species in marine reserves, we have been assessing changes in populations of spiny lobsters Panulirus argus and queen conch Strombus gigas, the two most commercially valuable and heavily exploited in the Caribbean. From the WCS Glover's Reef Marine Research Station at Middle Cay, we conducted quarterly population surveys and experiments in the no-fishing area ("conservation zone") and the fished area ("General Use Zone")of the Glover's Reef Marine Reserve. Our objectives were to assess and monitor their population dynamics, including density distribution, population size structure, reproductive activity, habitat requirements, and dispersal dynamics. We used these data in models to develop a predictive framework with which to evaluate reserve effectiveness. Due to the lack of data on key fish species, we also began to survey five of the most commercially valuable fish species in Belize. Our studies showed that, from 1996-1998 during which enforcement was minimal, density of lobsters and conch in the protected area was not different from density in the fished area. With consistent and effective enforcement by park rangers stationed at Middle Cay in late 1998, the density of lobsters and conch increased in the protected area, as predicted by our model for this reserve. The density of adult (exploitable) spiny lobsters increased by 300% and biomass increased by over 700% due mainly to survival and growth of large adults in the protected area.

    Item Type: Technical Reports (Technical Report)
    Related URLs:
      Publisher:
      Keywords: exploited species, marine reserve, population, assessments
      Subjects: (A) Biodiversity > (AC) Fish > (ACB) Marine
      (A) Biodiversity > (AF) Invertebrates > (AFB) Marine
      (H) Protected Areas > (HD) Marine Reserve
      Publication Sources: (3) Other Source > (3C) Other Universities
      Date Deposited: 12 Jan 2011 13:06
      Last Modified: 12 Jan 2011 13:06
      URI: http://eprints.uberibz.org/id/eprint/1192

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