732 



Fishery Bulletin 90(4), 1992 



X 

 I— 

 Q_ 

 UJ 

 Q 







25 

 50 

 75 





 25 

 50 [ 

 75 





 25 

 50 

 75 







25 



50 ■ 



75 



100 



#2 



#3 



#5 



AUG 21 



AUG 22 



AUG 24 



AUG 25 



AUG 25 



AUG 25 



^r-\m^ 1 f 



12 16 20 



HOUR 



8 12 



Figure 7 



Depths of yellowtail rockfish Sebastes flavidus nos. 2. 3. and 

 5 measured with pressure-telemetering transmitters during 

 21-25 August 1989. Bottom depths 75-99 m during this period. 



Vertical excursions of fish during late morning and after- 

 noon of August 1990 showed a similar pattern, with fish 

 occupying midwater depths and occasionally diving to deep 

 water (Fig. 8). The records for Fishes 2 and 3 show that these 

 fish descended toward the bottom immediately after release 

 and then rose to progressively shallower depths during the 

 next several hours. Synchronous vertical movements of 

 several fish were not common (Figs. 7, 8) but some did occur 

 among the three fish tracked during 25 August 1990 (Fig. 

 8). Sometimes fish dove as the vessel approached, perhaps 

 a response to ship noise (Ona and Godoe 1990), but at other 

 times fish descended when the vessel was not underway. 



Maximum rates of descent for fish shown in Figure 8 were 

 0. 16-0.40 m/sec; maximum ascents were 0.1 5-0.31 m/sec. 

 Figure 9 shows the dive of Fish 5 after release, with the most 

 rapid descent during the first minute, and slower rates in 

 the next 3 minutes. Rapid vertical movements were also 

 observed during 1989, with maximum rates of descent of 

 0.15-0.45 m/sec, and rates of ascent of 0.15m/sec. 



Discussion 



Homing and horizontal movements 



During all three years of the study, yellowtail rockfish on 

 Heceta Bank demonstrated site fidelity and homing. Dis- 

 placed fish returned from as far as 2nmi from their capture 

 site, and those released over rocky habitat and at similar 



depths returned to the location of capture in 1990. 

 Eleven of twelve fish tagged in 1990 returned to 

 or remained close to the original capture site 13 

 days after release. One fish that was displaced 0.5 

 nm returned overnight to the location where it 

 was captured. 



