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Fishery Bulletin 90(4). 1992 



44°05 '_ 



44°00 



124° 55 



124° 50 



Figure 2 



Topography of the southern portion of Heceta Bank and the 

 areas encompassed in Figures 3-6. Depths are in meters. 



Methods 



Yellowtail rockfish were captured with hook-and-line 

 during the daytime and placed in deck tanks with 

 circulating seawater. Acoustical transmitters were 

 inserted into the stomachs of large (42-54 cm fork 

 length), active, uninjured, unanesthetized fish with a 

 1cm diameter rod. Most fish were males. Fish were 

 released within 15min at the capture site or within 

 30min at displaced locations. Displaced fish were 

 released over bottom topography and depths known to 

 be inhabited by yellowtail rockfish (except in 1988), and 

 within 2nmi of the capture location to facilitate survey 

 of several release sites during a cruise. They were 

 tracked using a directional hydrophone and acoustical 

 receiver. Four fish tracked during 1989 were also 

 tagged with external Floy tags. 



Preliminary tagging 



Before this study began, a few tests were conducted 

 in circulating seawater tanks aboard ship or in the 

 laboratory to evaluate methods of tagging pelagic 

 rockfishes on five yellowtail and five black rockfishes 

 (Table 1). Dummy tags of the same dimensions and 

 weight as those used in the study were inserted into 

 the stomach or attached externally to the side of fish 

 under the dorsal fin. The external tag attachment, 



Table 1 



Information on tag retention in 5 yellowtail Sebastesflavidus, 

 and 5 black S. melanops, rockfishes aboard ship (S) and in the 

 laboratory ashore (L). ARM = tags with hooks (anti-regurgi- 

 tation mechanisms). 



Days to regurgitate 

 Date S/L Tag (or die) 



S. flavidus 



Sep 1988 



Aug 1990 



S. melanops 



Apr 1990 



Jul 1990 



External 

 Stomach 

 Stomach-ARM 



Stomach 

 Stomach-ARM 

 Stomach 

 Stomach-ARM 



(3) 

 .2,(6) 



11 



1 



9 



0.5 

 2,89 



similar to the one used by Matthews et al. (1990) for 

 benthic rockfish, caused one fish to list to one side and 

 interfered with its swimming. It died after 3 days in 

 the ship's tank. Three fish with tags inserted in their 

 stomachs had normal orientation in deck tanks and 

 were more active. One of these fish died after 6 days. 

 Stomach insertion of tags was used in this study. This 

 method is quick and minimizes handling and trauma 

 to the fish (Stasko and Pinock 1977). The major disad- 

 vantage was possible regurgitation of tags (Table 1 and 

 Results), although Stasko and Pincock (1977) reported 

 that transmitters inserted into the stomachs of many 

 other species of fishes were not disgorged. During the 

 last year, to increase the retention of tags in the 

 stomachs, one or two small (no. 18 steel dry fly) hooks 

 were attached to the ends of tags with epoxy as anti- 

 regurgitation mechanisms (ARM's). Hooks protruded 

 2 mm from the tag. In experiments in large aquaria or 

 tanks in the laboratory, tags with ARM's stayed inside 

 either black rockfish S. melanops or yellowtail rockfish 

 a total of 2, 9, 11, and 89 days compared with 0.5, 1, 

 1, and 2 days (and one that died after 6 days) for con- 

 trols without ARM'S (Table 1). 



Equipment 



Acoustical tracking equipment (VEMCO Ltd.) was used 

 in this study, including a VR-60 receiver with preset 

 channel frequencies, a telemetry decoder and display 

 unit, directional hydrophone, and transmitters or tags 

 with five different crystal-controlled frequencies. 

 Transmitters were 16mm in diameter, 48-65mm in 

 length, with batteries of 4.5, 9, 21, and 60 days rated 

 life-span. In 1990, transmitters with the same frequen- 

 cies had different pulse widths and pulse periods which 



