Population dynamics of Scyllarid lobsters of the genus Thenus spp. on the Queensland Australia) east coast I. Assessing the effects of tagging A.J. Courtney a,* ,M.G.Cosgrove a ,D.J.Die a,b a QDPI Southern Fisheries Centre, P.O. Box 76, Deception Bay 4508, Qld, Australia b CIMAS-RSMAS, University of Miami, 4600 Rickenbacker Causeway, Miami, FL 33149, USA Received14March2000;receivedinrevisedform29September2000;accepted10October2000 Abstract The effect of different combinations of tagging and release methods was examined on the survival, moulting, growth incrementandrecaptureratesofslipperlobsters Thenus spp.ontheQueenslandAustralia)eastcoastusinggeneralisedlinear modellingmethods.Laboratoryexperimentsindicatedthatwhiletaggingisunlikelytosigni®cantlyaffectthesurvivalrateor growthincrementsoflobsters,itislikelytolowertheincidenceofmoulting.Inthe®eld,recaptureratesoftaggedlobsters increased markedly by applying an antibiotic/antifungal ointment to the tag wound and by minimising the length of time lobsters were held on board prior to release. Recapture rates for Thenus orientalis declined by about 0.5% for every hour lobsterswereheldonboardpriortorelease,eventhoughtheywerekeptinaeratedseawater.Abouttwiceasmanymale T. orientalis wererecapturedcomparedtofemales.Reasonsforthismayberelatedtosizedifferencesbetweenthesexesandhow the®shersvaluedtherewardsfordifferentsizeclasses.ThesizeoftheT-baranchortagaffectedrecaptureratesof Thenus indicus;recaptureratesoflobsterstaggedwithsmalltagswereabout33%higherthanthosewithlargetags. Twodifferent methodsofreleasewerealsocompared;surfacereleaseandbottomcagerelease.Recaptureratesoflargelobstersandthose thatwereheldonboardforseveralhourspriortoreleasewereimprovedbyusingthebottomcagemethod.However,under some conditions, the cage may lower recapture rates relative to the surface release method, possibly because of increased stressandtraumafromcrowdinginthecage.Forbothspecies,growthincrementsofrecapturedlobstersincreasedwiththe period at liberty and declined with increasing lobster size. Females had signi®cantly larger growth increments than males. # 2001ElsevierScienceB.V.Allrightsreserved. Keywords: TaggingScyllarids; Thenus orientalis; Thenus indicus;Effectsoftags 1. Introduction Littleresearchhasbeencarriedoutonthepopula- tiondynamicsoflobstersfromthefamilyScyllaridae slipper lobsters) compared with the more valuable Palinuridae spiny rock lobsters) and Nephropidae clawed lobsters). Of the seven genera constituting the Scyllaridae, Thenus is the most economically importantJones,1988).InAustralia,logbookreports indicate that about 600±1000t of slipper lobsters, mostly Thenus spp., are caught annually, mainly as byproductofprawnandscalloptrawling.Mostofthe catch 400±840t) is landed in Queensland and is composed of two species Jones, 1988; Kailola Fisheries Research 53 2001) 251±261 * Correspondingauthor.Tel.: 61-7-3817-9582; fax: 61-7-3817-9555. E-mail address:courtnt@dpi.qld.gov.auA.J.Courtney). 0165-7836/01/$ ± see front matter # 2001ElsevierScienceB.V.Allrightsreserved. PII:S0165-783600)00274-5