876 



Fishery Bulletin 97(4), 1999 



The word "looping" was recorded when a swimming 

 fish made a turn of more than 90 degrees. 



"Lying" was recorded when a fish stopped swim- 

 ming and lay on the bottom, and included (for fish 

 that lay near hooks) direction to the closest baited 

 hook in relation to bottom current. 



"Biting" was recorded when a fish took a baited 

 hook completely into its mouth. 



An "incomplete biting" was recorded when a fish 

 touched a bait but the bait or hook was never com- 

 pletely within its mouth. 



"Grazing" was recorded if a fish bit at a piece of 

 bait that was not attached to a hook. Pieces of bait 

 would occasionally fall free from the hook during the 

 rushing following a bite. 



"Rushing" was recorded when a fish swam rapidly 

 forward with the bait or hook in its mouth. 



"Spitting" was recorded when bait was either spat 

 or pulled out of a fish's mouth. 



"Hooking" was recorded when a fish retained a 

 hook in its mouth for at least twenty seconds, usu- 

 ally while the fish struggled or fought violently. This 

 time period was chosen as consistent with that in 

 other literature on hooking behavior (Ferno et al., 

 1986; Huse and Ferno, 1990). However, hooking was 

 not recorded until completion of the rushing behav- 

 ior When biting was followed by rushing lasting more 

 than twenty seconds, which was in turn followed by 

 spitting, that portion of the behavior sequence was 

 listed as "biting, rushing, spitting." A fish that rested 

 after rushing with the hook still in its mouth, and 

 which subsequently after twenty seconds or more 

 rushed and spat out the hook, was listed as "biting, 

 rushing, hooking, lying, rushing, spitting." 



"Attacking" was recorded when a fish chased or 

 bit at another fish, either a halibut or one of the other 

 species in the viewing area. 



"Departure" was recorded, along with direction of 

 travel in relation to bottom current, when a fish left 

 the observation area. Occasionally, a fish would leave 

 the observation area and be identified on its subse- 

 quent return by a short duration of absence (less than 

 5 s), and by its length, and body markings. In these 

 cases, the period of nonobservation was recorded as 

 "looping." 



Sequential occurrences of either lying or looping 

 were coded as single occurrences. Consecutive lying 

 behaviors were coded as a single behavior occurrence 

 only when the subsequent lying was the result of a 

 small position shift and the fish did not shift to a 

 different bait. Twenty-one occurrences of behaviors 

 were considered compromised by the experimental 

 setup. A behavior transition beginning with a com- 

 promised behavior was considered invalid. For ex- 

 ample, a bite where the hook or gangion was wrapped 



around the frame was considered compromised, and 

 the transition to the following behavior was consid- 

 ered invalid. 



Direction in relation to bottom current 



Fish approaching or departing within 67.5° to either 

 side of and into the current were coded as "upstream." 

 Fish swimming within the next 45° on either side of 

 the current (within a 22.5° arc to a line perpendicu- 

 lar to the current) were coded as "right angle to the 

 current." Fish swimming within 67.5° to either side 

 of and out from the current were coded as "down- 

 stream." These same criteria were used to record the 

 direction in which a fish was lying in relation to a 

 bait. 



Results 



The number of halibut observed was 129, ranging 

 from none (on 19 sets) to a high of 19 (on one set). On 

 average, 5.6 halibut were observed on sets where at 

 least one halibut was seen, and the numbers of hali- 

 but caught per set ranged from to 4. Measured fish 

 ranged from 72 to 114 cm in length (mean=86.8 cm, 

 SD=11.4 cm). Calculated lengths ranged from 52 to 

 196 cm (mean=90.1 cm, SD=24.2 cm). 



Beliaviors and behavioral transitions 



The time until first appearance of the first halibut 

 in a set varied widely, ranging from almost immedi- 

 ately (18 s) to more than an hour after the gear was 

 set (1 h 1 min), and averaged 18 minutes (SD=13 

 min 32 s). For 29 fish that swam away immediately 

 after observation, the time between appearance and 

 departure ranged from 7 to 33 seconds (mean=9 s, 

 SD=7 s). Orientation in relation to bottom current 

 was noted for 93 halibut approaches (Fig. 3). Another 

 18 approaches were noted as occurring during slack 

 current. Of those fish that approached during periods 

 of noticeable current, 75% approached upstream, 9% 

 approached at right angles to the current, and 17% 

 approached downstream. 



Looping and lying were the most common behav- 

 iors, with 80 loopings recorded for 60 halibut and 70 

 lyings recorded for 45 halibut (Table 1). The average 

 durations of looping and lying behaviors were 40 and 

 14 seconds, respectively (Table 2). Fifty-seven bites 

 were observed; 48 halibut made a single bite, 3 hali- 

 but made 2 bites, and 1 halibut made 3 bites. A total 

 of 25 halibut were classed as hooked. The transition 

 matrix in Table 3 details 426 valid behavior transi- 

 tions constructed from the observations. The main 



