Abstract
The queen conch fishery in Jamaica is sustained by Pedro Bank, which is the main harvesting site located approximately 80 km south-west from Kingston. Due to its relative size, Pedro Bank has been subdivided into zones for management purposes by the Fisheries Division and the Veterinary Services Division. Understanding whether these sub-divisions reflect different sub-populations is critical for managing exploitation levels because fisheries management must demonstrate that harvesting does not endanger the future viability of the population as queen conch are on Appendix II of the Convention in Trade in Endangered Species of Wild Fauna and Flora (CITES). This determination is essential for the continued export to international markets such as the European Union. Two hundred and eight samples were collected across the entire Pedro Bank and were genetically characterized using nine polymorphic microsatellite loci. Population structure analysis for Lobatus gigas from Pedro Bank yielded low but significant values (FST = 0.009: p = 0.006) and suggested a high magnitude of gene flow indicative of a fit and viable population throughout the bank. Analysis of molecular variance (AMOVA) indicated a 100% variation within individual samples with little variation (0.9%) between populations. In contrast pairwise genetic comparisons identified significant differences between populations located to the south eastern and eastern region of the bank to those in the central and western locations. Bayesian clustering analysis also indicated the likelihood of two population sub-divisions (K = 2) on Pedro Bank. The results provided evidence of a weak but significant population structure which has crucial implications for the fishing industry as it suggests the use of ecosystem based management (EBM) in setting quotas to promote sustainable harvesting of L. gigas within each monitoring zone on Pedro Bank.
Highlights
The queen conch Lobatus gigas, (Linnaeus 1758), is an edible marine gastropod mollusk of the order Mesogastropoda, and one of six species of the family Strombidae found throughout the Caribbean region [1,2,3,4,5]
GenAlEx computations of Gstatistics such as FST adjusted for bias GST, and standardized G”ST which further corrected for bias when number of population is small (S1 Table), showed values which correlated with calculated FST, all microsatellite loci were included in further analysis and reported using the fixation index
Despite the occurrence of high genetic variability maintained by gene flow within the Pedro Bank population, Yamamichi and Innan [40] cautioned against making the assumption that randomly mating populations existed in nature as all populations are at least partially structured into subpopulations
Summary
The queen conch Lobatus gigas, (Linnaeus 1758), is an edible marine gastropod mollusk of the order Mesogastropoda, and one of six species of the family Strombidae found throughout the Caribbean region [1,2,3,4,5]. In 1992, Jamaica became the largest queen conch producer in the Caribbean, and the resources on Pedro Bank began to show signs of overexploitation following a pattern of conch population declines elsewhere in the region [9, 10] In response to these events and concerns, the Convention on the International Trade in Endangered Species of Wild Fauna and Flora (CITES), moved queen conch (L. gigas) to a listing in Appendix II. Mahon et al [9], predicted a collapse in the Jamaican Conch Fishery within three years if adequate management measures were not put in place to reduce or eliminate the harvesting of immature individuals This led to the drafting of the Conch Management Plan and between 2008 and 2011, conch production decreased from the unsustainable early 1990s harvest figures of close to 3,000 mt to around 400 mt, with a value of approximately 2.6 million US dollars [7, 10]. Some of the management regulations currently in place include, licensing of conch fishers and conch fishing vessels, closed season, transferable quota system based on National Total Allowable Catch (NTAC), minimum weight of processed meat, vessel monitoring system (VMS), fishing effort report on each fishing trip along with inspection of catch on landing and a conch export levy which is put into a fisheries management fund for the development of a sustainable fisheries sector in Jamaica [2, 13,14,15]
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