NOTE Kerstetter et al : Use of satellite archival tags to demonstrate survival of Makaiia nigricans 



941 



Tag deployment 



Four commercial longline vessels (48-70 feet LOA [length 

 overall] ) in the western North Atlantic Ocean were used 

 for the present study. All carried approximately 20 miles of 

 longline on one large spool, centrally mounted amidships. 

 Gear was set off the stern and retrieved from a hauling 

 station located on one side, approximately amidships — a 

 standard vessel configuration for the U.S. Gulf of Mexico 

 and east coast swordfish fleet. Fishing gear was also typical 

 for vessels in this fleet. A mainline of single-strand mono- 

 filament was used and a variety of terminal gear configu- 

 rations. Different lengths of dropper lines or numbers of 

 hooks between floats (or both) were used in attempts by 

 captains to increase billfish catch rates, although all modi- 

 fications to the gear were within the range of terminal gear 

 configurations used in this pelagic longline fishery. Leader 

 lengths ranged from 5 to 20 fathoms (9.2-36.6 m), and the 

 buoy drops generally were 10 to 15 fathoms (18.3-27.5 m). 

 Vessels in this study used a combination of "J" hooks (8/0- 

 9/0 sizes) and circle hooks ( 16/0 size). Bait was either mack- 

 erel (Scomber sp.) or squid (lllex sp.), and almost every set 

 used chemical lightsticks of varying colors attached to the 

 leader approximately 2 meters above the hook. 



PSATs were prepared for attachment to blue marlin 

 prior to departure of the vessels. A large, hydroscopic, sur- 

 gical-grade nylon tag head was attached to the PSAT with 

 an approximately 20 cm length of 300-pound-test Momoi® 

 brand (Momoi Fishing Co., Ako City, Japan) monofilament 

 line. Metal crimps, covered with black heat-shrink tubing 

 to minimize potential abrasion along the fish's body, were 

 used to attach the monofilament line to the PSAT and the 

 tag head. Individual PSATs were activated and tested at 

 the start of each fishing day prior to the morning haulback. 

 The white flotation bulbs of the 30-day tags were colored 

 black with a permanent marker prior to deployment to 

 decrease their visibility while attached to the fish. 



PSATs were attached to all blue marlin that were caught 

 on commercial pelagic longline gear, weighed more than 

 approximately 100 pounds (45.0 kg), and were observed 

 to be in relatively good physical condition, e.g. no large 

 wounds to the viscera. Of the ten blue marlin caught during 

 this study, all but one passed this minimum standard (the 

 one fish that was rejected arrived at the side of the vessel 

 missing the posterior half of its body due to several large 

 bites). Fish were brought alongside the vessels just aft of 

 the hauling station along the rail prior to tagging. Several 

 fish required up to two minutes to become calm enough 

 to be tagged accurately. Many longline captains attempt 

 to save as much leader material as possible from bycatch 

 fishes, and bringing a fish close to the vessel prior to cut- 

 ting the line is a common practice. The FV Ark Angel had 

 a removable section of rail that facilitated tag attachment; 

 on the other three vessels one was forced to lean out over a 

 rail to attach a tag. The average distance between the top 

 of the rail and the fish (freeboard) was approximately one 

 meter. The PSAT tag head was carefully inserted about 

 5-10 cm below (ventral) the midpoint of the anterior dorsal 

 fin. Tag heads were implanted to a depth of about 8 cm by 

 using a modified tagging applicator approximately 2 me- 



ters in length. A conventional streamer tag was attached 

 well posterior of the PSAT by using a standard tagging 

 applicator. Total tagging time, from identification of the fish 

 on the leader as a blue marlin to release following tagging, 

 was less than 5 minutes per fish. 



Blue marlin were released by the standard commercial 

 release protocol of cutting the leader near the hook and al- 

 lowing the hook to remain in the fish. Approximate weights 

 were estimated, and physical location of the hook noted for 

 each blue marlin. An "ACESS" condition scale, analogous 

 to the human neo-natal APGAR test (Apgar, 1953), was 

 developed to quickly evaluate the condition of each fish on a 

 scale of 0-10 by examining five characteristics and assign- 

 ing each a score of 0-2 (poor to good). These characteristics 

 included overall activity, color, condition of the eyes, stom- 

 ach eversion, and the general state of the body musculature 

 (presence of bites or lacerations). The time of day, vessel 

 location, and surface water temperature were recorded 

 immediately after tagging. The location of a hooked fish on 

 the longline was also noted in order to estimate the "soak 

 time" of that hook, i.e. the maximum time the fish could 

 have been hooked. 



Results and discussion 



Seven 5-day PSATs were deployed on blue marlin off Ber- 

 muda (;! = 1) and Florida (n=6) during 2000, and two 30-day 

 PSATs were deployed on blue marlin off North Carolina 

 and Virginia during the summer of 2001 (Tables 1 and 2). 

 Tags were attached onboard four vessels during six trips, 

 ranging from one to eleven fishing days each. The captains 

 all later indicated that the PSAT tagging procedures had 

 minimal interference with normal longlining operations. 



Although the captains attempted to target blue marlin 

 by fishing in different areas and with slightly different gear 

 than usual for swordfish trips, the catch rates for this spe- 

 cies were not notably different from the catch rates in NMFS 

 data; the catch rate for the trips in 2000 was slightly above 

 average for both season and location, whereas the catch rate 

 in 2001 was below the norm. Of the four trips in 2000, the 

 average CPUE for blue marlin was approximately 0.08 per 

 100 hooks (7 blue marlin/8650 estimated total hooks), which 

 is comparable to the reported blue marlin CPUE of 0.05 per 

 100 hooks for the NMFS southeast statistical region for the 

 third quarter of 1998 (Cramer, 2000). For all billfish, exclud- 

 ing swordfish, the CPUE was 0.15 per 100 hooks ( 12 billfish/ 

 8650 estimated total hooks). This value is also comparable 

 to the reported billfish CPUE of 0.12 per 100 hooks for the 

 NMFS southeast statistical region for the third quarter of 

 1998 (Cramer, 2000). For the three trips in 2001, the blue 

 marlin and billfish CPUEs were lower: 0.04 blue marlin per 

 100 hooks (3 blue marlin/7780 estimated total hooks) and 

 0.12 billfish per 100 hooks (9 billfish/7,780 estimated total 

 hooks). These similar catch rates, even when targeting bill- 

 fish, could be the result of decreased abundance, an inability 

 of the gear to effectively target billfish, or unfavorable water 

 conditions in the study areas. 



Of the ten blue marlin caught on the trips, nine were 

 alive and in relatively good physical condition. Based on 



