Abstract. — The distribution 

 and activities of rockfish, Sebastes 

 spp., inhabiting depths between 21 

 and 150 m in the coastal fjord of 

 Saanich Inlet, British Columbia, 

 were assessed by using the Pisces 

 PV submersible. Quillback rock- 

 fish, S. maliger, was the numeri- 

 cally dominant rockfish, attaining 

 a median density of 5.7 fishlOOm" 2 

 between 21 m and 100 m of depth. 

 Copper rockfish, S. caurinus, tiger 

 rockfish, S. nigrocinctus, yellowtail 

 rockfish, S. flavidus, yelloweye 

 rockfish, S. ruberrimus, and green- 

 striped rockfish, S. elongatus, were 

 all observed in consistently low 

 densities (<1 fish-lOOm" 2 ). The 

 greatest densities of rockfish oc- 

 curred over complex habitat of bro- 

 ken rock and boulders. The major- 

 ity (>50%) of rockfish were ob- 

 served either perched on open sub- 

 strate, hovering, or swimming. All 

 rockfish species were observed 

 near quillback rockfish (>75% oc- 

 currence); and quillback, copper, and 

 yellowtail rockfishes were also found 

 in association with conspecifics. 



Observations on the distribution 

 and activities of rockfish, 

 Sebastes spp., in Saanich Inlet, 

 British Columbia, from the 

 Pisces IV submersible 



Debra J. Murie* 

 Daryl C. Parkyn 

 Bruce G. Clapp* 

 Geoffrey G. Krause** 



Department of Biology. University of Victoria 

 Victoria, B.C.. Canada V8W 2Y2 



Prior to the advent of submersibles, 

 in situ observations of deep-water 

 demersal fish assemblages were 

 constrained by time-depth limita- 

 tions of SCUBA, which restrict ob- 

 servations offish assemblages pri- 

 marily to depths above 40 m (130 

 ft) (e.g. Moulton, 1977; Larson, 

 1980; Hallacher and Roberts, 1985; 

 Richards, 1987; Murie, 1991). Dis- 

 tributional studies of fishes inhab- 

 iting waters deeper than 30-40 m 

 have therefore relied on hook-and- 

 line surveys, box trapping, or net 

 trawling, all of which have known 

 biases and limitations (Westrheim, 

 1970; Uzmann et al., 1977; Krieger, 

 1993). The recent availability of 

 small submersibles for research 

 purposes has allowed direct visual 

 assessment of the depth distribu- 

 tion, density, and habitat of a vari- 

 ety of deep-water fish species (Uz- 

 mann et al., 1977; Carlson and 

 Straty, 1981; Richards, 1986; Dennis 

 and Bright 1988; Pearcy et al., 1989; 

 Stein et al., 1992; Krieger, 1993). 



Rockfish {Sebastes spp.) are im- 

 portant to nearshore recreational 

 and commercial fisheries along the 



northeastern Pacific coast (Patten, 

 1973; Richards, 1987). Many in- 

 shore rockfish species are believed 

 to be ecologically and morphologi- 

 cally similar, and are primarily 

 benthic, sedentary fishes (Patten, 

 1973; Moulton, 1977; Mathews and 

 Barker, 1983; Richards, 1986, 1987; 

 Murie, 1991). Distributions of 

 nearshore rockfish may depend on 

 a variety of factors, including 

 depth, habitat, and the presence of 

 con- and hetero-specifics. Various 

 species are known to segregate 

 bathymetrically (Larson, 1980; 

 Hallacher and Roberts, 1985; 

 Richards, 1986, 1987; Pearcy et al., 

 1989), reducing or eliminating the 

 potential for competitive interac- 

 tions between otherwise ecologi- 

 cally similar species (Larson, 1980). 

 Using a submersible, it is possible 

 to observe directly the species-spe- 

 cific depth distributions, as well as 

 to estimate each species' numerical 

 abundance or density with depth. 

 Changes in density with depth 

 within a rockfish species may ulti- 

 mately be related to fish size be- 

 cause rockfish size is often posi- 



Manuscript accepted 18 October 1993 

 Fishery Bulletin 92: 313-323 (1994) 



* Present address: Department of Fisheries and Oceans, Pacific Biological Station, Ma- 

 rine Fish Division, Nanaimo, B.C., Canada V9R 5K6 



"Present address: Explorations Unlimited, #1-1012 Richardson St., Victoria B C Canada 

 V8W 3C5. 



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