Pearcy: Movements of acoustically-tagged Sebastes flavidus 



733 



Carlson and Haight (1972) also found that adult 

 yellowtail rockfish returned to their home site, some 

 from as far as 22.5km, some after displacement to 

 other yellowtail schools, and some after 3 months in 

 captivity. In both studies, yellowtail rockfish homed 

 even if released at sites where the habitat was similar 

 to that at the capture site and near other schools of 

 yellowtail rockfish. This demonstrates fidelity to a 

 home site. 



Not all yellowtail rockfish demonstrate site fidelity, 

 however. Eight of ten recoveries of 153 yellowtail 

 rockfish tagged in Puget Sound were from the open 

 Washington coast, 58-2214 days after release, indicat- 

 ing an offshore migration probably related to the onset 

 of maturation of these fish (Mathews and Barker 1983). 

 In another study, Stanley (1988) tagged 4622 yellowtail 

 rockfish in Queen Charlotte Sound, British Columbia 

 during 1980 and 1981. As of 1987, the five that were 

 recovered moved from <10km to >300km. Of 9417 

 yellowtail rockfish tagged southwest of Vancouver 

 Island, 24 were recovered. Twelve moved < 10km while 

 others were recovered 23 to > 500 km from the tagging 

 location (Stanley 1988). 



The degree of site fidelity and movement of yellowtail 

 rockfish may be related to the bottom topography of 

 the tagging location. This appears to be the case for 

 black rockfish, another offshore pelagic species. Culver 

 (1987; B.N. Culver, Wash. Dep. Fish., Montesano, pers. 

 commun.) found that black rockfish tagged over a 

 5-year period from rocky habitats of northern Wash- 

 ington exhibited "no significant movement," whereas 

 fish tagged in areas that had sandy sediments or small 

 pinnacles off the central Washington and northern 

 Oregon coast displayed appreciable movements. Per- 

 haps yellowtail rockfish on Heceta Bank, and other 

 rocky banks, are less mobile than those inhabiting areas 

 with level seafloors. 



Carlson and Haight (1972) found that fish displaced 

 to sites across open water with depths >100m returned 

 to the site of capture with much less frequency than 

 did fish released along the adjacent coast in shallower 

 depths. One fish in my study, released in relatively deep 

 water off Heceta Bank and tracked continuously for 

 14 hours (Fish 4, Fig. 3), was not oriented toward its 

 home site. These observations suggest that homing is 

 most effective over relatively shallow water (<100m), 

 even though yellowtail rockfish are basically midwater 

 fish. Homing may also be influenced by topography. 

 Matthews et al. (1987) reported that displaced copper 

 and quillback rockfishes S. caurinus and S. maliger 

 returned to high-relief, but not to low-relief, reefs. 



The sensory mechanisms and environmental cues 

 used for homing and home-site recognition by yellowtail 

 rockfish are not known. Possibly the fish on Heceta 

 Bank recognized familiar topography and prominent 



"landmarks." Movements of up to 0.75nmi by yellow- 

 tail rockfish (Figs. 5 and 6) indicate that they do not 

 always have as small a home range and may range over 

 a large portion of the bank. Perhaps they learn visual 

 "landmarks" over much of the bank in this way. 



One fish returned to its home site from 925 m after 

 only 11 hours, mainly during the night when recogni- 

 tion of visual landmarks would have been more diffi- 

 cult. This fish returned home more rapidly than sub- 

 strate-associated copper and quillback rockfishes that 

 took 8-25 days to return home after displacement of 

 only 500 m (see Matthews 1990 for this and summary 

 of homing by other rockfishes). This suggests oriented 

 or directed movement. 



Eight of the twelve fish tagged in August 1990 were 

 relocated 1 month after release but were all south of 

 the capture location and scattered in an east-west direc- 

 tion. None was found within 0.1 nmi of the capture site. 

 This dispersal from the capture site suggests reduced 

 site fidelity and perhaps seasonal dissociation of indi- 

 viduals from the large schools observed earlier during 

 the summer. This dispersal may be associated with 

 seasonal changes, perhaps related to mating behavior 

 and the fact that most of the fish tagged were large 

 males. Carlson and Barr (1977) reported that the 

 spatial distribution and activity of yellowtail and dusky 

 {S. ciliatus) rockfishes differed markedly between 

 May-October, when they were seen in the water col- 

 umn and apparently actively feeding, and November- 

 April, when they withdrew into crevices between 

 boulders. Although no distinct seasonal changes are 

 known in the bathymetric distribution of yellowtail 

 rockfish (J. Tagart, Wash. Dep. Fish., Olympia, pers. 

 commun., Aug. 1991), the spatial distributions of other 

 species of rockfishes are known to change seasonally 

 (Miller and Geibel 1973, Patten 1973, Matthews et al. 

 1987). Several species of juvenile rockfishes are known 

 to move to deeper reefs with the onset of fall and 

 winter storms (Love et al. 1991). It would be interesting 

 to learn if the yellowtail rockfish of Heceta Bank 

 disperse and become more benthic during the late fall 

 and winter, and then if they eventually regroup at the 

 original capture location next spring after spawning, 

 or instead acquire new home sites on the bank. Studies 

 are obviously needed on seasonal and long-term move- 

 ments of yellowtail rockfish. 



Diel vertical movements 



Most yellowtail rockfish were seen swimming above the 

 bottom during submersible dives on Heceta Bank. 

 However, a few were observed resting on the sea floor. 

 More fish were observed inactive on the bottom dur- 

 ing night than day dives. The tagged yellowtail rockfish 

 of Heceta Bank were pelagic, swimming far above the 



