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The coastal fishing of the snail Titanostrombus galeatus is carried out in some coastal countries of the Tropical Eastern Pacific. In this study, the individual growth of T. galeatus that are fished in the community at Punta Maldonado was estimated. The size structure was made using the shell length (SL), and the growth parameters were estimated through the five Schnute cases, where cases 1, 2, and 5 describe asymptotic growth and cases 3 and 4 describe nonasymptotic growth. The male population was more abundant than the females, with 398 and 322 specimens, respectively, but the females were larger (198 ± 9.66 mm). In general, the average SL during the two sampling cycles was 196 ± 9.44 mm; this size was not significantly different between the first and second cycles (P = 0.98). Females had a greater range of SL (170–267 mm) compared with males (170–240 mm). The lengths of both sexes showed significant differences between months (P < 0.05). The multinomial analysis showed a multimodal SL distribution, with one to three modal groups for females and males. In growth, cases 2 and 5 were the ones that best describe the growth in females, in males the best were cases 5 and 2. According to the best case (case 2) in females, the growth curve is sigmoidal. In males, the best case (case 5) describes growth according to an inverted exponential curve. In relation to the estimated growth parameters, females showed faster growth than males, analyzed using Kimura's test. The present investigation is the first that reports the growth for both sexes of T. galeatus using the five cases of the Schnute model. The information generated can be used for management purposes, as this species is not currently regulated in Mexico. [ABSTRACT FROM AUTHOR]

The spider-like strombid Lambis lambis is widely distributed in the Indo-Pacific region and possesses morphological diversity. In the present study, the complete mitochondrial genomes of two morphologically different specimens of L. lambis that were collected in Sanya (SY) and Zhaoshu (ZS) islands of the South China Sea (namely L. lambis-SY and L. lambis-ZS) were sequenced. They were also compared with that of L. lambis previously published and sampled from coastal waters of Quanfu (QF) Island of the South China Sea (namely L. lambis-QF). The newly sequenced mitochondrial genomes L. lambis-SY and L. lambis-ZS contained 13 protein-coding genes, 22 transfer RNA genes, two ribosomal RNA genes, and several noncoding regions, indicating a similar pattern with respect to genome size, gene order, and nucleotide composition compared with that of L. lambis-QF. Although L. lambis-SY and L. lambis-ZS differed in shell morphology, the genetic distance between them was small. On the other hand, considerable genetic distance values were detected between L. lambis-QF and L. lambis-SY/L. lambis-ZS, suggesting that the former might be a possible cryptic species within L. lambis. The divergence of the cryptic lineage L. lambis-QF was dated to 4.6 Mya, falling in the lower Pliocene that corresponded to a paleoclimatic transition from cool to warm conditions. This study, therefore, suggests a correlation between paleoclimate change and speciation event. [ABSTRACT FROM AUTHOR]

Despite the commercial and cultural values of conch (family: Strombidae), there is a paucity of biological and ecological information to assist with the management of many conch fisheries. The common spider conch Lambis lambis, harvested throughout the Indo-Pacific for its meat and shell, is an example of such a data-deficient conch species. This study used passive acoustic tracking to estimate the spatial requirement and broad movement patterns of L. lambis over a 13-mo period in an extremely shallow (depth < 2 m) lagoonal environment of the Cocos (Keeling) Islands (CKI). The mean kernel utilization density home range for L. lambis during the study period was estimated at 18,059 ± 3,298 m2 (n = 14). The mean home range was also estimated monthly and was found to be significantly larger in January (austral summer) than in the preceding October and November, likely a function of the reproductive cycle of L. lambis at CKI. Estimated home range size and animal size were not found to be correlated, and there were no observed differences between the sexes. The results show that, in an environment of preferable habitat with adequate resources, L. lambis have a home range that is relatively small when compared with studies of the Caribbean queen conch Lobatus gigas. The information on the spatial requirement and movement ecology for L. lambis at CKI from this study will assist with informing management techniques, not only for this fishery but also for other small conch fisheries worldwide. [ABSTRACT FROM AUTHOR]