Baqueiro Cárdenas Erick, Aldana Aranda Dalila
Rev Biol Trop. 2014 Mar;62(1):45-57.
The queen conch, Strombus gigas, is a gastropod of commercial importance in the Caribbean. Population studies are based on size frequency analysis, using either length or weight parameters for the whole live organism. This contribution used mark-recapture data to estimate the Von Bertalanffy equation parameters and population number variation within a non harvest population from a protected area, to clarify the biometric parameters that better suit for the whole population, or for the juvenile and adult fractions. Conchs from Xel-Ha Park were monthly sampled from November 2001 to August 2005. Every conch found was measured and marked with a numbered tag that identified month and locality; and monthly abundance was estimated with Jolly's method. Length, lip thickness and weight increments were used to estimate the Von Bertalanffy growth equation parameters with Appeldoorn's subroutine of FISAT program. The population number varied through the study, with a minimum of 49 in April 2003 and maximum of 9 848 during June 2005. Conchs make only temporary use of Xel-Ha cove. Shell length gave the best fit for the juvenile fraction: L(infinity)=251, K=0.3, C=0.8 Wp=0.3; and lip thickness for adults: L(infinity)=47.78, K=0.17, C=0.1, Wp=0.86, while, the whole population was better represented by weight: L(infinity)=3850, K=0.36, C=0.8, Wp=0.3. A maximum age of 19 years was estimated from the population. Natural mortality was 0.49/year for juveniles and 0.29/year for adults. There were two pulses of recruitment: fall-winter and summer. It is concluded that population studies from length frequency data, should be analyzed independently in two groups, shell for the juvenile fraction and lip thickness for the adult fraction, or if it is not possible to analyze the population fractions separately, weight should be used to avoid miss calculation of the age structure.
大凤螺（Strombus gigas）是加勒比地区具有商业重要性的腹足纲动物。种群研究基于大小频率分析，使用整个活体生物的长度或重量参数。本研究利用标记重捕数据来估计保护区内非捕捞种群的冯·贝塔朗菲方程参数和种群数量变化，以阐明更适合整个种群、幼体部分或成体部分的生物特征参数。2001年11月至2005年8月，每月从谢哈公园采集大凤螺样本。对发现的每只大凤螺进行测量并用带有识别月份和地点的编号标签进行标记；每月丰度用乔利方法估计。利用FISAT程序的阿佩尔多恩子程序，通过长度、唇厚度和重量增量来估计冯·贝塔朗菲生长方程参数。在研究过程中，种群数量有所变化，2003年4月最少为49只，2005年6月最多为9848只。大凤螺仅临时使用谢哈湾。壳长最适合幼体部分：L(∞)=251，K = 0.3，C = 0.8，Wp = 0.3；唇厚度适合成体：L(∞)=47.78，K = 0.17，C = 0.1，Wp = 0.86，而整个种群用重量表示更好：L(∞)=3850，K = 0.36，C = 0.8，Wp = 0.3。据估计该种群的最大年龄为19岁。幼体的自然死亡率为每年0.49，成体为每年0.29。有两个补充高峰：秋冬和夏季。得出的结论是，基于长度频率数据的种群研究，应将幼体部分按壳长、成体部分按唇厚度分为两组独立分析，或者如果无法分别分析种群部分，则应使用重量来避免年龄结构计算错误。
