Ichthyophonus and Mycobacterium‐like bacterial infections in commercially‐important rockfish, Sebastes spp., in the eastern North Pacific Ocean

Abstract

Recently there has been an increased concern about the status of demersal ®sh stocks, particularly rock®sh, Sebastes spp. (family Sebastidae), in the Paci®c Northwest (Musick, Harbin, Berkeley, Brugess, Eklund, Findley, Gilmore, Golden, Ha, Huntsman, McGovern, Parker, Poss, Sala, Schmidt, Sedberry, Weeks & Wright 2000). Offshore (slope and shelf) rock®sh ®sheries of particular concern (i.e. those that have declined signi®cantly in recent years) include canary rock®sh, Sebastes pinniger (Gill), widow rock®sh, S. entomelas (Jordan & Gilbert), Paci®c Ocean perch, S. alutus (Gilbert), yellowtail rock®sh, S. avidus (Ayres), and boccacio, S. paucispinus (Ayres) (Paci®c Fisheries Management Council 2000). Examples of rock®sh species that are considered at risk include S. pinniger and S. alutus, which are listed as `vulnerable' with a 77±93% and 81±91% decline, respectively. Sebastes avidus stocks are at 63% of pristine levels, but this stock is expected to decline because of poor recruitment (Paci®c Fisheries Management Council 2000). In a recent survey of marine ®sh for salmon pathogens conducted off the coast of British Columbia, we found that about 30% of the rock®sh examined were infected with the chlamydialike agent responsible for epitheliocystis, but most were light infections with insigni®cant associated pathological changes (Kent, Traxler, Kieser, Richard, Dawe, Shaw, Prosperi-Porta, Ketcheson & Evelyn 1998). In addition, Kent & Myers (2000) described severe liver lesions in redstripe rock®sh, S. proriger (Jordan & Gilbert), associated with a putative herpes virus. In 2000, Fisheries and Oceans Canada and Oregon Department of Fish and Wildlife research scientists conducted stock surveys of demersal ®sh, and we used this opportunity to conduct disease examinations of these ®sh to elucidate possible roles that diseases play in the demise of some of these stocks. Four species of rock®sh (S. alutus, S. avidus, S. reedi and S. pinniger) were examined from collections conducted off the coasts of Oregon on 5 May 2000 (latitude 44.35.00 N) and 20 September 2000 (latitude 44.40.00 N), and Washington (latitude 46.30.00 N) on 10 May 2000, except that S. reedi was not examined in the latter. An additional collection of S. alutus and S. avidus from Oregon was examined in September 2000. Also included here are data from 89 S. avidus, 56 S. alutus and 56 S. pinniger collected from three localities off British Columbia in the summer of 1999 (Table 1). The southernmost area in British Columbia was off the West coast of Vancouver Journal of Fish Diseases 2001, 24, 427±431