,c DEPaRTtdEliT sF f,g J qirBl!i:r1r: f ;; & LAII0i,ifr il AGEI{ig$iT DEPARTMENTOF FISHERIESAND FAUNA WESTERN AUSTRALIA REPORTNo. 10 AN INVESTIGATIONINTO THE STATUSOF INTRODUCEDTROUT (Salmo spp.) IN WESTERN AUSTRALIA By Dr. N.M. Morrissy Published by the Director of Fisheries and Fauna, Perth. under the authority of the Hon. Ron Davies, M.L.A; Minister fo! Fisheries and Fauna _LL6 rssrf,rlon v:rrr8fsnv N&tss|[ NI a ooos ouTee I \ '-,/ ilooEt (EcocoEfi{r iro soJvJsttr{J oJ;NI NofwiItss r.tr $v €T-[€J+snYur3+s3.ll ?TrnedT)Ir€ saTreqsT$ .;o luauFedaq 88.iss 0 ^^ffmErr\Tmq \,\JIIT I Introduction II Distribution (a) lreas coveretl by stocking activities 3 (t) w.t"rs il which trout occr:r ) D istributioa naP 't3 (c) ct:rnate (a) r'row of streans 1B (e) water temperatr:res 18 21 (f ) Spaqning faci-lities lII Aburd-ance (a) An6J-ers' catches ao (b) Sanplir€ IT Sr:rcaarlr antl Conclusions 39 (a) oistritution 39 4q (b,l Abundance v Recomenrl ati-ons ' o o 39 VI References 4o )+1 Appendix Centre Photographic Pl-ates Pa€es. aaJaqr,c$to srr^rn+a.r3tqqs1,3: qltlr . .s.ra19ue uosTJBduoc u-t a.req qsTJ op oqn aq+ a.rB TnJssaccns roH (t) apqsTJ seceld pue .senbluqcel 8uc1ftre Jo uoT+ecTlsTrldos 6s.ra13ue Jo JeqrEnuJo srrr.re+uT uog1e11ollxa 1e s1drne11e+uasard Jo +uoqrre eq1 sg 1eq4 (7) S,tgpnb pe8pe1nota1ceJo seTrar{sTJ a.r€ eJeq+ aJaqlAaJeqfi.asTe sJa+er q11n a.reduoc oJarl +noJ+ pgid Jo EuoT+€Tndod .;o aoueprmq€prrB uoTlnqTJ+sTp ar{+ saop l^oH ( | ) :uoT+€JapTsuocarrnba"r suol -1senb ?u-trao11oJer{+ uoT+en+Ts +uo.rmc sq+ Jo TesT€rdde TTnJ € Jog '(9951 'sToc.or$) eTq"TT"^€ s?r so+€+s ure+s€e eq+ uT +6aq oq+ q+Tir aTq€.reduocft4rqsTJ +er{+ raeT-o.aq+ o+ ( eq-L66L sr,r4ue3) ,ftaqs1.; +noJ+ TnJssaccns e roJ pooJ +ueTcT.lJnsul peplao.rd s.:a1e.u eq+ +eq+ uoTsnlcuoc aq+ norJ pel.rea uolu;do leuroJrrT +c?J qI .eJnTT?J ro ssaccns e paSpnf aq ?Tnoc uoT+"zT+?uTTccp+noJ+ Jeq+aqn uo uoT+eulrogrF , .pacuamoc r€aTc ou s?.|[ aJaq+ L96L LrE ser lesle.rrlde luas a:d eq+ uoq.tr . steatt 9E uaq+ arorn 8ug1se1 saT+T^T+oeftr-rncols pa8uolo.rd aq1 a4ldsaq .(+sa;o?u-t TecTro+sTr{ Jo saT+TAT+o€ Jo s+rmooce roJ . L96l-e161. .f1a!cog uoT+€zT+errgTccy+nor; uor&ft- uo+raquad arl+ Jo €+JoiIaU Tenuuq aes) +oTJ+sTq uer.r€.Ueq+ uT rfJJ SuTs?oTaJ 1xr€ €^o pa+JodET ftrF{c+tsq uT ?a?€eccns tlfgceileo a1ea3.:d e u_t 8u31oe t.ua1x 1::lt3 .JrI usrli Lt5! ocrlFs +ser-q+nos Je[oT aq+ uT uo+Jequed +€ ?oJlueo ueaq seq srageu 8u_'r4oo+sJoJ +noJ+ Jo uoT+cnpoJd .f.reqcleg .saT+TT€nb qsg.;-ame8 ou 3uoaaeu .qcTg$ s€r{ aq+ a{TT eT$?o ,(TqAFq oTTq.& (fa nfqU fr6oIFoA-EiiC' ffi) .relqqoc eq+ sT +uasard qsTJ a^T+€u e3.re1 .f{uo aqj .slaleu aseql Jo +sortr u-t luasa.rd sT (r{+TrS ffiCuTnuo=T-ffi) uo.r.zemsnouaS-rpu1 a9.re1 oq& .qs.TJeue8e uo .f.raqi1;: lrods .meleue ue apg.io.rd o+ eTT€J+snVuJo+sejl oq+ pacnpor+rt Jo +sa!.-qqn!ls Jo sJo+en ?rr€TuT o+u-T-"+tffit uaaq a^?q +noJ+ (uocpr€qcgg TT?ffi'€g'B) rcqnger pu€ (.T o@E) rrlrcxq qlos Nori[3n@&INI r It is a-lso llpcrtant to conper': tne situaticn in Western Austrai"ia with the history of i-ntroduced- trout il Eastern Austra-l-ia. and New Zealadid"whe re tirere ltas b,).,ri]; (t) n" i-rlitiuf stoc<ing of sl;re:uas rhich il aIL these other fish- eries resu-lted in the establisbment of self-sust ai_ning wild populations of trout in the fatter half of the last centurv ( usualJ.y very mal-l liberations, PO - 2OOOfry, were success- fuJ- ). tr'ollowed by, (2) fishi-ng of hi6h quelity on relati-vely unexploited- stocks in waters little interfered with by naa. .And in recent years, (.r) fi"hi"e of grad.ual-ly declining quality, particularly ne ar large npnJ.roe ^f n^nr'lrJ-.inn drra in vvLrnwor rJ,llJ]16fi<hino rh; /la<+a,,^+i^n ^f habitat. This situation has started since the l99t s. Ptrases (1) ana (Z) have been called, respectively, the accli.:natiz- '193-l). ation and maintena-nce stages (lobbs plase 13) ^ay be caffed the destructive stage. Hobbs 119J7) tu New Zea-l-aridard Nichol-t-s (1958) in Tasrnania showed that releases of artificial ly propa6ated. trout had. often been c ont irrued urnecessarif-y ilto stage (2) sfuce trout, once established., reproduce s atisfactoriJ-y. This situation exists jn N.2., Tasmalia, nost of Victoria aid N.S.W., and a srnall paxt of S.A. for streams. However, there a.re some parts of these fisheries which have had to continuously be restocked si-nce their J-nception because natural spaming is inad-equate since survival- of fish is poor due to su.mner climate. For exarople stocking is necessary in dams, fakes or streams where there are no feed-er streams with suitable spawni:ng gravef. Stocking is aL6o necessar;r to maintain fishabfe stocks i-n rnargi-nal areas where surviva.l- is poor, iI some years, due to high summer temperatules. The latter is the case for streams in western N.S"W., as l,ake (1917) poi.rrted out, as weLL as in western Victoria, and in S.A. These points become relevant when the l-atitude of the south-west, the altitude of the waters, a.rd the hot dry strnmer cfimate a.r:e considered. A d-istinctlon between the grointh rate ard. d-ensity of fish is need-ed in ev a,l-uatj:rg the success of the fishery in terms of angling benefits. To many a-nglers the captr.rre of a few Large trout per day is conparable with the capture of many snall- fish only a few of which are just legal size. Trout in narginal waters where density is fi-{nit ed by sr.loner cond-itions usually grow ertremely rapidly reachilg legal-size in a year or so. In contrast waters in colder regions usua-l-l-yhave a high density of fish but the fish grow more slowly. .J€+€^! pTqJn+ q+T^{ suep TTEUS .t edrffi 'suoo8el 'saryT .Ja+€r'ti J?aTc q+T /i,rsue? .ro Jo TTEUS . suep uoT+€8tJJE Er€ srlep ,{1ddns .za1e.pt . Z a&Cf .saTJ?+nqTJ+ JTar{+ pue sJa^Tu . 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