Conserving Rockfishes: Barotrauma and Descending Devices in the Northeast Pacific

Descending devices allow rockfishes that are not being retained, such as the Tiger Rockfish Sebastes nigrocinctus pictured here, to be released near depth of capture, minimizing complications related surface release floating, barotrauma injuries, and predation. Rockfishes (Sebastes spp.) a diverse group fish in order Scorpaeniformes distributed globally but concentrated North Pacific. Recognizable by their large eyes distinct dorsal spines, genus is united shared characteristics including live births, head highly spinous fin succeeded soft-rayed portion, musculature attached closed (physoclistous) swim bladder. Despite these similarities, there an astonishing amount morphological variation among species streamlined bodies for active schooling midwater environments thick, heavily spined more sedentary, benthic lifestyles. can found from extremely deep slope shallow inshore rocky bottoms favor complex substrates, crevices kelp forests. Whatever preferred habitat, they tend remain close small home ranges throughout relatively long lives; most rockfish late-maturing, some even hundreds years. It older, larger females contribute population growth, although individuals have become much less common due decades intense fishing pressure. The establishment industrial methods has led devastating declines populations along northeastern Pacific coast, resulting many becoming threatened or endangered. In response, network Conservation Areas (RCAs) was implemented British Columbia (BC), prohibiting groundfish selected regions with suitable habitat. addition designating RCAs, Fisheries Oceans Canada (DFO) applied conservation measures increased catch accountability (including bycatch discards), improved stock assessment techniques, strategies decrease angler-induced mortality. efforts, overfished recovered. life history, reproductive, physiological make them susceptible pressure, particularly bladders, which substantially high post-release bladders function both buoyancy control sound production. Since no external connection uptake gases, limited gradual adjustments controlled passive diffusion gases into out bloodstream surrounding water through gills. While this functional mechanism typical situ adjustments, problems arise when captured, inevitably subjecting rapid change pressure brought surface. When gas enclosed bladder (deep water) low (shallow water), expansion occurs, causing decompression injuries referred barotrauma. External symptoms include those easily noticeable anglers: extended esophagus (esophageal eversion), roll mouth commonly mistaken bladder, well bulging (pop eye exophthalmia). Less obvious signs tight swollen abdomen, branchiostegal membrane (near throat operculum), bubbles within (membrane ocular emphysema, respectively). Internal damage also occur form tears, ruptures hemorrhaging various internal organs. Many barotraumatic subtle may go unseen discards anglers. barotrauma, sometimes unable recompress return depth, float at contend temperature shock seabird marine mammal Consequently, catch-and-release approach ineffective reducing mortality rates species, valid management RCAs records need consider sublethal effects effective. recent years, deepwater mechanisms (DRMs) descending widely used recreational angling community method recompressing increasing survival following capture release. Weighted, inverted hooks, milk crates, commercially available main types DRMs currently use. Various U.S. jurisdictions recommended required use cannot DFO introduced condition license 2019. novel requirements, compliance unknown regions. Additionally, while increase compared certain release, degree survivorship bolstered unknown. morphology vary so severity differ well, therefore, species-specific research always extrapolated entire genus. studies been done on short-term investigations long-term (i.e., months, years) very limited, significant gaps exist BC. Salish Sea, encompassing Strait Georgia, Juan de Fuca, Puget Sound, ideal location study rockfishes. This temperate coastal region vast amounts outcrops forests, community. Georgia off coast BC features incredible diversity 41 valued risk extent one few groups organisms own protected BC, Sea. this, several local still endangered showing recovery, highlighting urgent explore further efforts. A juvenile Quillback maliger nestles red soft coral Gersemia rubiformis. Substrate habitat important all stages, juveniles. Yelloweye ruberrimus captured using hook line exhibits esophageal eversion, protruding esophagus, caused anterior during ascent rolls fish's mouth. mistake anglers assume mouth, detrimentally puncture effort vent built-up gas. Pop (exophthalmia) visible. often affected pop (exophthalmia), (ocular emphysema), shown left (right side photograph). Our field observations revealed symmetrical, presentation emphysema delayed. Gas visible gill coverings opercula) maliger, just exhibited underside fully exposed, unnoticed We observed around operculum surface, indicating escape membranes region. Vermilion miniatus slowly lowered over vessel stormy Sea will device its lower lip, setting closest depth. Above it, camera set up record descent University Victoria researchers performing mark–recapture investigate impacts survival. Top: Copper caurinus tagged soon device. Bottom: S. released, collection valuable data length, symptoms. work conducted Nanaimo, Columbia, Canada, where impressive found.