Variability in size at maturity and reproductive season of queen conch Lobatus gigas (Gastropoda: Strombidae) in the Wider Caribbean Region

• Published in: Fisheries research 2018-05, Vol.201, p.18-25
• Main Authors: Boman, Erik Maitz, Graaf, Martin de, Nagelkerke, Leopold A.J., Stoner, Allan W., Bissada, Caroline E., Avila-Poveda, Omar Hernando, Baqueiro-Cardenas, Erick Raul, Smaal, Aad C.
• Format: Article
• Language: English
• Subjects: Caribbean; Fisheries management; Mollusks; Reproductive biology; Sexual dimorphism
• ISSN: 0165-7836; 1872-6763
• DOI: 10.1016/j.fishres.2017.12.016

•Maturity occurs after maximum SL is reached and after sizable growth in LT.•Does not show size at maturity variation according to the temperature-size rule.•Sexual dimorphism in size (lip thickness) at 50% maturity, with larger females.•Variation of annual temperature regulates temporality of the reproductive season.•Need for an update of current minimum size and closed season regulation. Queen conch (Lobatus gigas), is an economically and culturally important marine gastropod. The species is subject to extensive exploitation throughout large parts of the Caribbean which has led to a decrease in population densities across much of the species’ distribution range. Hence, there is a need for protective measures to safeguard the reproductive stock. This requires a better estimation of its size at maturity, which is best quantified as the thickness of the lip that the shell develops after reaching its maximum length. The lip thickness at 50% maturity (LT50) was determined using a logistic and an accumulation model, from seven representative location of distribution of this species in the Wider Caribbean Region. LT50 of both females (7–14 mm) and males (4–11.5 mm) varied between different locations in the Caribbean, although it did not correspond with variation in water temperature. In most cases females had a larger LT50 than males indicating sexual dimorphism. LT50 values estimated with the logistic model were smaller (7–14 mm for females, 4–11.5 mm for males) than values estimated with the accumulation model (13–26 mm for females, 16–24 mm for males), showing an overestimation of LT50 in queen conch in previous studies which used the accumulation model to estimate LT50. Locations with a relatively high variation in water temperature had a significantly shorter reproductive season. The implementation of adequate minimum size regulation based on lip thickness (ca. 15 mm) and a Caribbean wide seasonal closure (May–September) using the most recent biological information from this study, taking into consideration the local differences in LT50 and reproductive season, will assist in developing a long term sustainable queen conch fishery in the Caribbean.