FISHERY BULLETIN: VOL. 84, NO. 2 



44° 50' N 



- 44° 40' 



44° 30' 



124° 50' W 



124° 40' 



Figure 2.— The demersal trawl station grid occupied during 1980 and 1981 widow 

 rockfish behavior studies on the Nelson Island ground off Newport, OR. The 16 trawl 

 stations are marked with a (+). 



school of widow rockfish, which was sampled with 

 midwater trawl gear (Fig. 4). It was not possible to 

 stay in contact with the school long enough to 

 observe diel changes in behavior. 



When the study was repeated in April 1981, only 

 4 of 20 demersal tows contained widow rockfish. Two 

 of these tows contained only a single specimen each, 

 while the others contained 20 and 28 specimens. 

 Results again indicated that widow rockfish were 

 relatively unavailable to demersal trawl gear and that 

 their distribution was somewhat more closely 

 associated with Nelson Island during the night than 

 during the day (Fig. 3, 1981). 



It is important to be able to distinguish widow 

 rockfish from other species on the basis of echosign 

 in order to draw conclusions about their behavior, 

 distribution, and abundance Commercial fishermen 

 targeting on this species have shown that this can 



be done. We characterized the echosign produced by 

 widow rockfish and other species occurring on widow 

 rockfish grounds using echograms obtained aboard 

 research and commercial vessels and through discus- 

 sions with commercial fishermen on echograms and 

 corresponding catches. Widow rockfish schools most 

 frequently appeared on echograms as tall, slender 

 columns suspended over an irregular bottom (Fig. 

 5). These were often accompanied by less dense 

 layers probably composed of salps and other zoo- 

 plankton. Widow rockfish were sometimes present 

 during evening and morning in smaller schools high 

 in the water column (Fig. 6). Shortbelly rockfish, 

 Sebastes jordani, and redstripe rockfish, S. proriger, 

 have similar echosign characteristics and are most 

 likely to be confused with widow rockfish off the 

 Oregon coast (Figs. 7, 8). Other midwater targets 

 in the area were identified as layered schools of 



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