ABSTRACT: Indices of lobster abundance and population demography are often derived from pot catch rate data and rely upon constant catchability. However, there is evidence in clawed lobsters, and some spiny lobsters, that catchability is affected by conspecifics present in pots, and that this effect is sex- and size-dependent. For the first time, this study investigated this effect in Panulirus cygnus, an economically important spiny lobster species endemic to Western Australia. Three studies: (1) aquaria trials, (2) pot seeding experiments, and (3) field surveys, were used to investigate how the presence of large male and female conspecifics influence catchability in smaller, immature P. cygnus. Large P. cygnus generally reduced the catchability of small conspecifics; large males by 26-33% and large females by 14-27%. The effect of large females was complex and varied seasonally, dependent on the sex of the small lobster. Conspecific-related catchability should be a vital consideration when interpreting the results of pot-based surveys, especially if population demography changes. Analysis of the mean catch rate of large P. cygnus over the past 29 yr indicates that fishery management changes have created significant variations in the abundance of large lobsters. This is likely to have affected the catchability of smaller lobsters, which will have implications for the use of time series catch rate data in the stock assessment and management of this fishery.

中文翻译：

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大小很重要：大龙虾会降低小物种的捕获能力

摘要：龙虾丰度和人口人口统计指标通常是从盆栽捕捞率数据中得出的，并依赖于恒定的捕捞能力。但是，有爪龙虾和一些多刺龙虾中有证据表明，捕捞能力受到盆中存在的同种异形的影响，并且这种影响取决于性别和大小。这项研究首次调查了西澳大利亚地区特有的经济上重要的多刺龙虾物种Panulirus cygnus的这种效应。三项研究：（1）水族箱试验，（2）锅播种试验，以及（3）实地调查，被用来研究的大型男性和女性同种存在于小的，不成熟如何影响捕P.天鹅。大天鹅通常会降低小特定物种的可捕获性；大型男性的比例为26-33％，大型女性的比例为14-27％。大雌性的影响是复杂的，并且随季节而变化，这取决于小龙虾的性别。在解释基于罐的调查结果时，特别是在人口人口统计发生变化的情况下，与种相关的可捕获性应该是至关重要的考虑因素。对过去29年中大天鹅对虾平均捕获率的分析表明，渔业管理的变化已导致大龙虾数量的显着变化。这很可能影响了小龙虾的捕捞能力，这将对在该渔业的种群评估和管理中使用时间序列捕捞率数据产生影响。