The Queen conch Strombus gigas, a large marine gastropod, is found in the territorial waters of 36 countries and tettitories in the Caribbean region. Over the past decades, intensive fishing has led to population declines resultin gin the total or temporal closure of the fishery in a number of locations. Since November 1992, the species has been included in Appendix II of CITES. In 2002, concerns about levels of illegal trade led to a "review of Significant Trade" in queen conch by TRAFFIC on behalf of the CITES. For this review, data on commercial fisherisies landings, CITES trade data, stock status, and management measures were compiled with the assistance of CITES and fisheries authorities, and regional experts.
Large-scale distribution of a large, commercially significant gastropod, Strombus gigas (queen conch), was investigated in a II ,OOO-haregion of the Great Bahama Bank near Lee Stocking Island, Exuma Cays. Maps of depth and seagrass biomass, generated with Landsat thematic mapper data, and a 4-year survey of juvenile conch distribution showed that most of the juveniles were in aggregations located in 1.5-4.0-m water depth. Although general locations of juvenile conch aggregations remained the same between 1989 and 1992, their total surface area occupied only about 1.5% of the 8,300 ha of seagrass habitat available. Locations of only the most persistent long-term aggregations could be predicted on the basis of preferred seagrass biomass (30-80 g dry weight m-2); however, important conch nurseries were always located in tidal channels which brought clear, oligotrophic water from the Exuma Sound. Harmonic analysis of water temperature data from sites with and without juvenile aggregations showed that conch nurseries were subject to flushing with oceanic water on every tide, whereas non-conch sites reflected only diurnal heating and cooling of bank water. Relationships between circulation and juvenile conch distribution on the Great Bahama Bank may be related directly to larval recruitment, or indirectly to aspects of nutrient cycling and food production; evidence for both mechanisms exists. Although exact locations of conch aggregations shift from year to year, these shifts appear to occur within larger nursery habitats, the boundaries of which are set by a precise combination of physical and biological factors. Because most meadows are probably unsuitable for this severely ovcrfished species, critical nursery habitats should be identified and protected.
ABSTRACT: There is increasing recognition that habitats should be managed as part of fisheries management. It is generally assumed that amount of suitable habitat is linked to production of de- mersal species and that maps of bottom type will provide the information needed to conserve essen- tial habitats. In this review, a synthesis of nursery habitat is made for Strombus gigas (queen conch), a large, economically important gastropod in the Caribbean region. Juveniles occur on a variety of bottom types over their geographic range. In the Bahamas, nurseries occur in specific locations within large, beds of seagrass, while obvious characteristics of the benthic environment such as seagrass density, depth and sediment type are not good predictors of suitable habitat. Rather, nurseries persist where competent larvae are concentrated by tidal circulation and where settlement occurs selec- tively. Nursery locations provide for high juvenile growth resulting from macroalgal production not evident in maps of algal biomass, and they provide for low mortality compared with seemingly simi- lar surroundings. Therefore, critical habitats for queen conch juveniles are determined by the inter- section of habitat features and ecological processes that combine to yield high rates of recruitment and survivorship. While maps of bottom type are a good beginning for habitat management, they can be traps without good knowledge of ecological processes. A demersal species can occupy different substrata over its geographic range, different life stages often depend upon different bottom types, and specific locations can be more important than particular habitat forms. Habitat management must be designed to conserve habitat function and not just form. Implicit in the concept of ‘essential habitat’ is the fact that expendable habitat exists, and we need to prevent losses of working habitat because of inadequate protection, restoration or mitigation. Key nurseries may represent distinctive or even anomalous conditions.
An important scientific workshop on queen conch was held in Caracas, Ven ezuela, in July 1991. This workshop and the proceedings that emerged from it (Appeldoom and Rodriguez, 1994) pro vided a good background on the status of research on biology, fisheries, and mariculture of the queen conch. Be cause the general biology of the queen conch is already relatively well known, the purpose of this paper is to summa rize some of the important advances made in the study of queen conch since the 1991 workshop. Emphasis has been placed on topics related to the ecology of queen conch that are most relevant to fisheries management and stock re habilitation. In the following sections an attempt has been made to draw con clusions about habitat requirements for the species, mortality of juveniles as it relates to stock rehabilitation and en hancement, larval ecology and fisher ies oceanography of the species, and the conservation of reproductive stocks.
This report describes the activities and outputs of the project to improve and harmonize scientific approaches required for the sustainable management of queen conch.
Five case studies were undertaken for the countries: The Bahamas, Belize, Dominican Republic, Grenada and Haiti. For each case study, a report of findings, conclusions and recommendations were completed. With the exception of Haiti, each country was visited and information obtained from stakeholders and local sources.
A regional review of scientific and management approaches to the management of queen conch was completed, containing regional management options. Information for regional review was obtained from the cases studies, CRFM, other international organisations and other contacts in the region.
Based upon the information obtained from the case studies and review, a 3-day regional validation workshop was conducted in St. Vincent, 6th-8th June 2013.
A Regional Management Options Paper was successfully produced and endorsed by the validation workshop for further consideration by CRFM and CARICOM states.
The main recommendation is that the Regional Management Options Paper should be used as the basis for a regional queen conch management plan by CARICOM states. Implementing the recommendations in the paper will not only improve management, but also increase international confidence in the region’s fishery management, reducing the chance of trade sanctions.
This report also places emphasis on developing analytical approaches for harvest strategies and specifically support for The Bahamas in developing its harvest strategy.
Despite years of regional discussions and trade regulation under the Convention on International Trade in Endangered Species (CITES), most queen conch fisheries suffer from uncoordinated management and unsustain- able harvest. Queen conch is listed in Appendix II of the treaty and, as such, each shipment of the species must be accompanied by a permit for which the exporting country has made findings that the specimens have been legally acquired and that the trade is sustainable. The Appendix-II listing for Queen conch has proven to be a useful complement to national management pro- grams. In April 2003, the CITES Secretariat released a lengthy analysis of the Caribbean conch fisheries and associated international trade. Subsequently, the International Queen Conch Initiative (IQCI) convened its members to discuss this report and renew calls for regional cooperation on law enforce- ment, management measures, and capacity building. A list of regional commitments resulted from this meeting, and will be formally transmitted to the CITES process as the trade analysis unfolds. These commitments will be considered as CITES considers how member countries should act to reduce poaching, coordinate management, and ensure sustainable international trade in the species. This entire process, known as the CITES “review of significant trade” will require governments in the Wider Caribbean to bring about sustainable use of this resource, via binding management advice from an international technical committee. Specific CITES actions and timelines for their completion will be available by autumn 2003. This report discusses the reasons for a second CITES trade analysis, presents fundamentals of the CITES significant trade review process, highlights the outcomes of a 2003 technical committee meeting, and makes some conclusions about the future of regional conch management in the wider Caribbean.
Egg masses of Strombus gigas, S. costatus, and S. pugilus were gathered from depths of 3 to 18 m in the western part of the Los Roques Archipelago, Venezuela. S. gigas spawns from early July through mid-November. S. costatus begins spawning in November, and continues until May. S. pugilus egg masses were first discovered on March 29. Eggs were hatched in the laboratory and veligers fed enriched natural cultures of phytoplankton. Juveniles were fed various species of algae which grew naturally on the sides of the tanks, plus algae growing on rocks, which were introduced into the tanks. Preliminary growth data show S. gigas reaching a length of 31.7 mm in 171 days after hatching. After 175 days, S. costatus reached 42.7 mm. S. pugilus attained a mean length of 20.9 mm after 121 days. Mariculture potential and some aspects of the ecology of the three species, especially the juveniles, are discussed.
Queen conch, Strombus gigas (Linnaeus, 1758), is a species of significant economic importance in the Caribbean Sea, exploited mainly for consumption by a ravenous export market in the USA and French West Indies. Because populations have been depleted throughout the Caribbean region by over shing, present conservation efforts are focused on regional harmonization of conch management to improve its sustainability. In the present study, we compare the reproductive cycle of S. gigas from eight sites (Florida Keys, Alacranes Reef, Chinchorro Bank, San Pedro, San Andrés Archipelago, Guadeloupe, Martinique, and Barbados) to consider the biological rationale for a harmonized closed shing season. A framework recognizing four reproductive stages for males and females is proposed for use in future studies. Signi cant di erences were found in the timing and intensity of reproductively active stages between conch from western and eastern sites in the wider Caribbean region. Two distinct reproductive strategies were observed: (1) continuous and low level of reproduction throughout the year (Alacranes Reef, San Pedro, and San Andrés Archipelago); and (2) a discrete and intense reproductive period with rapid gametogenesis (Guadeloupe, Martinique, and Barbados). Queen conch required a temperature of ≥27.7 °C to initiate gametogenesis; and were found in the resting stage below 27.5 °C. Based on a comparison of spawning seasons across the reproductive strategies observed, we suggest that the most “biologically meaningful” period for a closed season for the entire western central Atlantic would need to incorporate the months of June to September, at a minimum, to over regional protection for spawners.
The present study was undertaken in nine locations along the north coast of Havana province; at the reefs located east and south of Batabano Gulf, Jardines de la Reina Archipelago and Cabo Crue (west coast of Oriente); in the period between May 1972 and May 1974.
The investigation deals with the influence of the environment on the growth rate of the queen conch (Strombus gigas, Linnaeus). Observed growth rates are between 4 and 8cm per year. Shallow waters (less than 2m deep) are better fit for rapid development. The morphology of the shell changes, according to the intensity of growth: large, light shells with numerous short spines and well defined spiral markings, are evidence of rapid growth. Growth is positively correlated with final size of the shell and negatively correlated with duration of the development period (juvenile stage).
Measures of population abundance, patterns of distribution and habitat characteristics are given. The preliminary values of the mortality coefficient are between 1.01 and 1.90. Other biological data are also given.
The Convention on International Trade in Endangered Species (CITES) Authority issued injunctions in 2003 and 2004 to halt export trade of Caribbean queen conch (Strombus gigas) from several countries and initiated reviews of a number of other conch-producing countries. The current regula- tory framework for regional conch fisheries has obviously failed to protect stocks. I present a case study of the Belize conch fishery to examine fishing impacts, effectiveness of existing regulations, and potential for population recovery. Fishery-independent data from a no-take marine reserve indicated that unfished density and biomass were nearly an order of magnitude greater than in comparable fished areas. Size structure of the protected population showed that an average of 38% of the legal catch may consist of juvenile conch. The spawning potential ratio indicated that the fished stock is severely over- exploited, and furthermore, the protected population has not compensated to make the local fishery sustainable. Under these conditions, a moratorium under CITES may be warranted. Until stock assessment models are refined, action should be taken to reduce juvenile fishing mortality, extend closed seasons, and enforce a network of functional no-take reserves in essential habitat.