Results of Survey Lac Bay, Bonaire for Queen Conch (Strombus gigas) and Seagrass characterization in 2007


In 1999 a survey was carried out (Lott, 2000) to estimate the conch population and determine the status of the seagrass beds in Lac Bay, Bonaire. Since 1999 the recreational use of Lac has increased, new structures have been built around Lac and illegal conch fishing still goes on (conch fishing is forbidden by Marine Ordinance of 1991). In order to assess the effects of the moratorium and the impact of increased activity in and around Lac the 1999 survey has been repeated, applying the same methods. Fieldwork was carried out from the end of May 2007 through the beginning of October 2007.


The main conclusion from this study is that the moratorium on conch fishing seems to be effective as Lac Bay’s conch population has increased; however, the cover of turtlegrass has diminished, which is most likely linked to an increase in anthropogenic disturbance of Lac.

  • The conch population has increased: in the 51,000 m2 survey area, 223 live conch were found, against 111 in 1999.
  • Adult conch were found (4% of the population) while in 1999 no adult conch were recorded.
  • The cover of turtlegrass has diminished in most of the 17 grids (2,142 quadrats of 1 m2 ) studied; these grids were spread over Lac Bay. Grid Cai showed no reduction in cover.
  • Trampling from windsurfers, snorkelers and other users of Lac Bay plays a major role in the reduction of turtlegrass.
  • Cover by macro algae has changed but not necessarily diminished; in some grids the cover increased, in others it decreased.
  • The number of most invertebrates has decreased.

Management Recommendations:

  • Further study on Lac Bay’s species composition.
  • Further study on Lac Bay’s water quality.

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