Gassman Juan, López Rojas Héctor, Padrón Dana
Rev Biol Trop. 2017 Mar;65(1):181-94.
Snooks C. undecimalis and C. ensiferus are important fishery resources in their distribution area. In Venezuela they are caught by artisanal fisheries along the entire coast. However, studies on their biology that would help establish fishing regulations are scarce. To study reproduction aspects of these species, we analyzed 1 325 individuals of C. undecimalis and 2 025 of C. ensiferus caught by artisanal fishing in the Laguna de Tacarigua in Northern Venezuela, from July 2009 to September 2010. Total length, total weight, sex and stage of gonadal development were recorded. The sex ratio varied throughout the year: there was a significant difference in favor of C. undecimalis males (1.5:1), and C. ensiferus females (1:3.3). Differences were also evident in the sexual proportion at each size group. For both species, males dominated in the lower size ranges while females dominated in the larger size ranges. These results suggested sequential hermaphroditism (protrandry) in both species. Size at sexual maturity (Lm50) for C. undecimalis was ♀= 73.6 and ♂= 59.3 cm, and ♀= 26 and ♂= 21.5 cm for C. ensiferus. C. ensiferus reproduced throughout the year with two periods of higher intensity (August to September and February to April). Although we found very few mature individuals for C. undecimalis, February showed an important reproduction peak. Growth differences were found between males and females of C. undecimalis: positive allometry for females (P= 0.0022L3.353) and negative allometry for males (P= 0.0108L2.945). Both males and females of C. ensiferus showed a positive allometric relationship (P= 0.0049*L3.235). Lack of fishing regulations and controls, evidenced in this study by significant volumes of immature individuals in the catches, and the particular reproductive biology of these species, strongly indicates the need to establish regulations to ensure their responsible use. We recommend establishing a closed season during the first quarter of the year and minimum catch sizes for both species.
斯努克斯氏无十带鲹和剑状无十带鲹是其分布区域内重要的渔业资源。在委内瑞拉，它们被沿岸的个体渔业捕获。然而，有助于制定捕捞规定的关于它们生物学特性的研究却很匮乏。为了研究这些物种的繁殖情况，我们分析了2009年7月至2010年9月在委内瑞拉北部塔卡里瓜湖被个体渔业捕获的1325尾斯努克斯氏无十带鲹和2025尾剑状无十带鲹。记录了鱼的全长、总重、性别和性腺发育阶段。性别比例全年都有所不同：斯努克斯氏无十带鲹雄性占显著优势（1.5:1），剑状无十带鲹雌性占显著优势（1:3.3）。每个体长组的性别比例差异也很明显。对于这两个物种，在较小体长范围内雄性占主导，而在较大体长范围内雌性占主导。这些结果表明这两个物种都存在顺序性雌雄同体现象（雄性先熟）。斯努克斯氏无十带鲹的性成熟体长（Lm50）为♀=73.6厘米，♂=59.3厘米，剑状无十带鲹为♀=26厘米，♂=21.5厘米。剑状无十带鲹全年都有繁殖，有两个繁殖强度较高的时期（8月至9月和2月至4月）。虽然我们发现斯努克斯氏无十带鲹的成熟个体很少，但2月出现了一个重要的繁殖高峰。斯努克斯氏无十带鲹的雌雄个体生长存在差异：雌性为正异速生长（P = 0.0022×L3.353），雄性为负异速生长（P = 0.0108×L2.945）。剑状无十带鲹的雌雄个体都呈现正异速生长关系（P = 0.0049×L3.235）。本研究中捕获的大量未成熟个体证明了缺乏捕捞规定和管控，以及这些物种特殊的繁殖生物学特性，都强烈表明需要制定规定以确保对它们的合理利用。我们建议在每年第一季度设立禁渔期，并规定这两个物种的最小捕捞尺寸。
