Relationships between density of mature adults and mating frequency in queen conch (Strombus gigas Linnaeus, 1758) were observed at three sites in the central Bahamas including one no-take marine reserve (Exuma Cays Land and Sea Park) and two historically important fishing grounds (Berry Islands and Andros Island). No mating was observed in any one count with density < 47 adults ha −1 , consistent with an earlier study suggesting a mate-finding Allee effect in queen conch. e unfished site had larger and older conch, and mating at that site increased rapidly with adult density, reaching an asymptote at 12%-14% of the population mating at highest density levels. Logistic modeling showed that a 90% probability of mating occurred at 100 adults ha −1. Mating frequencies increased more slowly with density on the fishing grounds; asymptotic mating frequencies were 6.3% in the Berry Islands and just 2.3% at Andros Island. In contrast to the marine reserve, 90% probability of mating required 350 and 570 adults ha −1 at Andros Island and the Berry Islands, respectively. Higher densities required for successful mating in the fished areas were associated with numerical dominance by small, thick-shelled adults. e small phenotype in adults appears to result from selectivity imposed by fishing pressure, and those adults had low mating frequencies, compounding the density effect on reproduction. Because releases of hatchery-reared queen conch have not been successful, preserving the integrity of spawner density and population structure will be critical for conch conservation.

No abstract

No abstract

Aim:A detailed understanding of spatial genetic structure (SGS) and the factors driving contemporary patterns of gene flow and genetic diversity are fundamental for developing conservation and management plans for marine fisheries. We performed a detailed study of SGS and genetic diversity throughout the overharvested queen conch (Lobatus gigas) fishery. Caribbean countries were presented as major populations to examine transboundary patterns of population differentiation.Location: Nineteen locations in the greater Caribbean from Anguilla, the Bahamas, Belize, Caribbean Netherlands, Honduras, Jamaica, Mexico, Turks and Caicos, and the USA. Methods:We genotyped 643 individuals with nine microsatellites. Population genetic and multivariate analyses characterized SGS. We tested the alternate hypotheses: (1) SGS is randomly distributed in space or (2) pairwise genetic structure among sites is correlated with oceanic distance (IBOD). Results: Our study found that L. gigas does not form a single panmictic population in the greater Caribbean. Significant levels of genetic differentiation were identified between Caribbean countries (F CT = 0.011; p = .0001), within Caribbean countries (F SC = 0.003; p = .001), and among sites irrespective of geographic location (F ST = 0.013; p = .0001). Gene flow across the greater Caribbean was constrained by oceanic distance (p = .0009; Mantel r = .40), which acted to isolate local populations.Main conclusions: Gene flow over the spatial scale of the entire Caribbean basin is constrained by oceanic distance, which may impede the natural recovery of overfished L. gigas populations. Our results suggest a careful blend of local and international management will be required to ensure long-term sustainability for the species. K E Y W O R D Sconnectivity, conservation, dispersal, fisheries, genetics, spatial | 1293 TRUELOVE ET aL.

Effectiveness of a marine protected area (MPA) in supporting fisheries productivity depends upon replenishment patterns, both in supplying recruits to surrounding fished areas and having a sustainable spawning stock in the MPA. Surveys for queen conch Strombus gigas were made in 2011 at 2 locations in the Exuma Cays, The Bahamas, for direct comparison with surveys conducted during the early 1990s at Warderick Wells (WW) near the center of the Exuma Cays Land and Sea Park (ECLSP) and at a fished site near Lee Stocking Island (LSI). There was no change in adult conch density and abundance in the shallow bank environment at LSI where numbers were already low in 1991, but numbers declined 91% in the deeper shelf waters. At WW, the adult population declined 69% on the bank and 6% on the island shelf. Unlike observations made in the 1990s, queen conch reproductive behavior near LSI is now rare. Average age of adult conch (indicated by shell thickness) at LSI decreased significantly during the 20 yr period between surveys, while average age increased at WW and juvenile abundance decreased. These results show that the LSI population is being overfished and the WW population is senescing because of low recruitment. In 2011, the ECLSP continued to be an important source of larvae for downstream populations because of abundant spawners in the shelf environment. However, it is clear that the reserve is not self-sustaining for queen conch, and sustainable fishing in the Exuma Cays will depend upon a network of MPAs along with other management measures to reduce fishing mortality. KEY WORDS: Marine protected area · Population structure · Reproduction · Queen conch · Bahamas Resale or republication not permitted without written consent of the publisherMar Ecol Prog Ser 460: [101][102][103][104][105][106][107][108][109][110][111][112][113][114] 2012 lacking, a large amount of literature has accumulated discussing reserve location and size and the role of MPA networks in the context of population connectivity, stock replenishment, and fisheries management (Lubchenco et al. 2003, Jones et al. 2007, Kininmonth et al. 2011.The efficacy of an MPA for both preservation of a stock and contributions to surrounding fisheries will depend upon either the self-sustaining capacity of the population within the MPA or recruitment from outside. Despite considerable optimism about the role of MPAs as an important tool in fisheries management, the limitations of MPA design and the importance of broader impacts outside the reserves themselves have become clear (Allison et al. 1998, Gaines et al. 2003, Mora et al. 2006, Botsford et al. 2009). Botsford et al. (2001) pointed out a decade ago that the reserve areas likely to be implemented by local governments may not be large enough to sustain natural communities unless fishing and other deleterious effects outside the reserves are limited. Stochastic processes associated with larval transport and population processes including recruitment, along with the human component of fisheries m...