Baqueiro-Cardenas, E.R.

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. 

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 (7–14mm for females, 4–11.5mm for males) than values estimated with the accumulation model (13–26mm for females, 16–24mm 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