Behavior of Nine Species of Pacific Rockfish after Hook‐and‐Line Capture, Recompression, and Release

Abstract

We evaluated the effect of barotrauma on the behavior of nine species of Pacific rockfish Sebastes spp. after hook‐and‐line capture and release using a video‐equipped underwater release cage. Sampling was conducted across a range of bottom depths (12–194 m), mostly where barotrauma resulting from an expanded swim bladder and gaseous release of dissolved blood gases would be expected. Behavioral impairment from barotrauma was depth related but highly species specific. Increased depth of capture was associated with lower behavioral scores for black rockfish S. melanops, blue rockfish S. mystinus, and yelloweye rockfish S. ruberrimus, but not for canary rockfish S. pinniger. Behaviorally impaired fish showed a decreased ability to maintain vertical orientation and were slower in exiting the release cage. Species differed in the degree of behavioral impairment resulting from barotrauma and in how rapidly behavioral impairment increased with depth of capture. When captured at depths between 40 and 99 m, blue rockfish showed the most serious behavioral impairment, 8 of 18 (44%) failing to swim away at the time of release and simply drifting off in a sideways or upside‐down posture. In the same depth range all of the other species sampled showed only moderate behavioral impairment, which is indicative of some potential for survival after discard by the fishery. Surface observations of the external signs of barotrauma were variable among species and were poor indicators of which species would show behavioral impairment upon release at depth. Within individual species, however, the external signs of barotrauma were associated with an increased probability of behavioral impairment at time of release.

The post-release behaviour and fate of tournament-caught smallmouth bass after ‘fizzing’ to alleviate distended swim bladders

“…We observed that fizzed fish were found at the bottom (but rightside up) of the observation containers, while unfizzed fish floated on their sides or backs prior to release. Several studies have argued that fizzing can reduce some problems associated with barotrauma (i.e., allowing fish to return to depth), but it may have little effect on any tissue and physiological damage that have already been inflicted (e.g., Morrissey et al, 2005;Hannah and Matteson, 2007). This is of particular concern in tournaments where fish are held in live-wells at atmospheric pressure for several hours prior to release.…”

Bycatch of rockfish and other species in British Columbia spot prawn traps: Preliminary assessment using research traps

“…All rockfish species are vulnerable to overfishing due to their low population growth rates resulting from late age at maturity and variable recruitment (Love et al, 2002). Being caught as bycatch in the trap fishery could impose additional mortality because discarded rockfish are unlikely to survive swim bladder rupture and other physiological and physical damage caused by rapid ascent of retrieved traps (Brill et al, 2008;Hannah and Matteson, 2007). All sources of rockfish mortality, including bycatch, should be evaluated.…”

Tailoring Ecological Monitoring to Individual Marine Reserves: Comparing Longline to Hook‐and‐Line Gear to Monitor Fish Species

“…However, incidence of barotrauma among rockfish species was much lower in the longline catch compared with hook-and-line sampling. This may be in part due to differing rates of acclimation among species (Hannah and Matteson 2007) and the slower retrieval rates of the longline (compared with the rapid reeling up of fish caught on hookand-line gear), which may allow for a longer acclimation period. As barotrauma reduces the survival rates of released fish, longlines may have an advantage over hook-and-line sampling in postrelease survival rates.…”