Queen Conch

Introduction

1. The queen conch (Strombus gigas) is one of the most important fishery resources in the Caribbean in terms of its annual landings and its social and economic importance. Queen conch is an edible marine gastropod of the Caribbean Region that has been listed in Appendix II of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) and Annex III of the Protocol Concerning Specially Protected Areas and Wildlife (SPAW) of the regional Convention for the Protection and Development of the Marine Environment of the Wider Caribbean Region (Cartagena Convention).
2. While many problems of the fisheries in the region have been addressed, there is still significant concern over the status of some stocks and management in the region. As a result, a Queen Conch Expert Workshop was organised by the Caribbean Fisheries Management Council in Miami, USA, 22–24 May 2012 to discuss the various constraints on improving the management of the queen conch fisheries. This report contains the findings, conclusions and recommendations of this workshop. 

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. 

Queen conch (Lobatus gigas) is an important food source and export product for Belize, where extraction is regulated by shell length (SL) and market clean weight (MCW) limits. However, lip thickness (LT) limits are used to manage juvenile mortality and reduce risk of growth overfishing in other countries. Empirical studies suggest relationships between LT and sexual maturity vary spatially and need to be determined locally. This study was conducted to determine the most reliable, easily measurable proxy indicator(s) of maturity and associated target size limits in L. gigas that can effectively restrict harvest of juveniles. Morphological measures (SL, LT, lip width, unprocessed meat weight, MCW, operculum dimensions), gonadosomatic index (GSI) and histological evaluations were recorded from L. gigas collected in PHMR before, during, and after the L. gigas closed season. Upon determining Period 2 (during closed season) as the peak reproductive period, relationships between these variables in Period 2 were examined. No relationship was found in males between SL and maturity, and was weak in females, whereas there were significant curvilinear relationships between LT and GSI for both sexes, suggesting urgent need to base size limits on LT not SL. LT at which 50% of the population was mature (LT50) was 15.51 mm for females and 12.33 mm for males, therefore a 16 mm LT limit is recommended. MCW of female L. gigas was also significantly related to GSI, indicating MCW may be an appropriate management tool in conjunction with LT as it can be measured at landing sites whereas shells are usually discarded at sea. However, MCW at which 50% of females were mature (MCW50) was 199 g and many individuals exceeding LT50 had MCW <199 g, suggesting the current 85 g MCW limit is too low to protect juveniles yet 199 g MCW limit would be too high to substitute the recommended LT limit at landing sites. To minimize short-term impacts yet maximize long-term benefits to fishers’ livelihoods, multi-stage adaptive management is recommended that integrates initial catch reductions, followed by introduction of size limits of 16 mm LT, and 150 g MCW. Adjustable LT and MCW limits determined by fishery simulation could later be introduced. 

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. 

Prior to 2014 little research had been conducted on the Anguilla conch fishery aside from indirect data collected by the Department of Fisheries and Marine Resources (DFMR) during annual monitoring of reef and seagrass areas, or via generic landing site visits and other observations. Due to a suspected inadequacy of current regulations combined with concerns relating to fishery sustainability, DFMR facilitated two small groups of visiting researchers in 2014 and 2015 to fill this knowledge gap. The work conducted, combined with that carried out recently in neighboring islands, confirmed that the current minimum landing size of 18 cm shell length for Lobatus gigas (formerly Strombus gigas) is a poor indicator of conch maturity, with up to 94% of individuals of this size still immature. Histological analysis of gonad samples revealed that there is no correlation between shell length and maturity, with the development of a flared lip a much more precise indicator. It was concluded that a lip thickness of 10 mm should replace the minimum shell length legislation in order to move towards a more sustainable fishery. Semi-cleaned meat weight (digestive glands removed), essential to allow assessment of conch chucked by fishers while out at sea, currently set at 225 g was concluded to be sufficient given that meat weight can reduce as conch pass well beyond maturity. By accompanying fishers while harvesting L. gigas compliance to regulations seemed good, although it was recognized that this could be due to a researcher being present onboard. From in-water habitat and L. gigas abundance surveys a patchy distribution of conch were observed which led to an overall conclusion that the conch fishery in Anguilla is likely to be unsustainable, and so the need for legislative change is urgent. Based on boat activity surveys during the study period it was estimated that 69,190 lbs of semi-cleaned meat is landed per year by the fishery across an active fleet of seven full to part-time vessels (thus excluding recreational or small scale catches). This represents an estimated 6% of the fishable biomass. It is suggested that to ensure sustainability, this fishery should not be developed much beyond its current size and consideration be given to the issuance of special species specific licenses, and the introduction of recreational catch limits. This is especially relevant due to L. gigas being listed in 1992 under Appendix II of Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES), of which Anguilla is party. It has been suggested that consideration be given to the possibility of conch farming in Anguilla, although the present study found this an unviable option due to a lack of extensive protected shallow water habitats and the difficulty in obtaining hatchery seed or juveniles for culture. 

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.

The overall objective of this 10-year Regional Queen Conch Fishery Management and Conservation Plan is to guide the implementation of a set of identified management measures that can be applied at the regional or sub-regional level for the sustainability of queen conch populations and for the maintenance of a healthy fishery and livelihood of the people involved in the fishery.

The ecosystem approach forms the basis of this Regional Queen Conch Fishery Management and Conservation Plan, enhancing partnerships and collaboration throughout the Wider Caribbean region to improve the long-term governance of queen conch fisheries across the Caribbean.

The Regional Queen Conch Fishery Management and Conservation Plan was formulated with the following specific objectives:

1. To improve the collection and integration of scientific data needed to determine the overall queen conch population status as the basis for the application of ecosystem-based management.

2. To harmonize measures aimed at increasing the stability of the queen conch population and to implement best-management practices for a sustainable fishery.

3. To increase coordination and collaboration toward achieving better education and outreach, monitoring and research, co-management and strengthening, optimizing and harmonizing regional governance arrangements.

4. To adopt regional management measures, which incorporate the precautionary approach.. 

Morphometric measurements were taken from queen conch (Strombus gigas) from various sections of the Antigua and Barbuda shelf to: 1) ascertain if there were spatial variability regarding morphology; 2) analyse length-weight relationships for various maturation stages; 3) develop statistically valid conversion factors for different levels of processed conch meat; and 4) assess current management regimes (e.g., minimum size / weight). For both juvenile and adult conch, shell length differed significantly among the coastal groupings, p < 0.001. Shell lip thickness, an indicator of the age, was also significantly different among the coasts (p < 0.001), where conch from the north and west coast were significantly older than those from the east or south coast of Antigua (p < 0.001). Significant sexual dimorphism was only detected for adult conch (p < 0.001), with females being 4% larger than their male counterpart. The mean lip thickness for conch collected from commercial fishing trips was 25.0 mm (N = 785, S.D. = 5.5 mm) indicating that divers were targeting an old population however the sex ratio of the allowable catch (minimum weight of 225g) was favouring the harvesting of female conch, X2 (1, N = 711) = 4.26, p < 0.05. Conversion factors differed significantly among maturation stages (juvenile, sub adult, adult and old adult), p < 0.001; hence the use of a single conversion factor to transform processed conch to nominal weight is problematic since conversion factor is dependent on the age structure of the population. These morphological differences require a multifaceted management approach (closed season, protected areas, etc) to ensure the long-term sustainability of the fishery. 

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 reproductive cycle of the Queen Conch, S. gigas, in the Archipelago of San Andres, Providencia and Santa Catalina, Colombia, was estimated during a 1-year period (February 2003– January 2004) from monthly observations on histological sections of gonads collected from sexually mature individuals. The resting, gametogenic, mature, and post-spawning stages were present almost all year long, while spawners (or “gamete producers” as S. gigas does not spawn into the water but copulates) appeared only twice, from March to April (6% males and 20% females) and in September (6% males, 43% females). The results of our histological analyses are congruent with those of previous works on S. gigas in San Andres Archipelago based only in mating and egg-laying behaviors, and in the presence of egg-masses as proxies for spawning. The current fishing season of Queen Conch in San Andres Archipelago extends from November 1 to May 31, according to Resolution No. 179 of May 5, 1995, and overlaps with the first reproductive event of this species. As harvesting egg-laying females during March–April could place the recovery of the population at risk, we suggest two possible scenarios to modify the current fishing regulation: a) reducing the fishing season from November 1 to March 1, and b) opening two fishing seasons per year, one from November 1 to March 1 and the other from June 1 to July 31. The success of any of these management options can only be evaluated by implementing a monitoring plan in San Andres Archipelago. This simple procedure will help protect this species, improve its sustainability through time, and guarantee the availability of the resource to local fishermen.