Large Spiny Lobsters Reduce the Catchability of Small Conspecifics
Vol. 666: 99–113, 2021 MARINE ECOLOGY PROGRESS SERIES Published May 20 https://doi.org/10.3354/meps13695 Mar Ecol Prog Ser OPEN ACCESS Size matters: large spiny lobsters reduce the catchability of small conspecifics Emma-Jade Tuffley1,2,3,*, Simon de Lestang2, Jason How2, Tim Langlois1,3 1School of Biological Sciences, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia 2Aquatic Science and Assessment, Department of Primary Industries and Regional Development, 39 Northside Drive, Hillarys, WA 6025, Australia 3The UWA Oceans Institute, Indian Ocean Marine Research Centre, Cnr. of Fairway and Service Road 4, Crawley, WA 6009, Australia 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 cyg nus, 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 investi- gate 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 demo graphy changes.
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