Factors Influencing Postrelease Predation for a Catch‐And‐Release Tropical Flats Fishery with a High Predator Burden

Abstract

Postrelease predation (PRP) of fishes released by anglers is a potentially significant contributor to overall mortality in recreational fisheries. We quantified PRP and examined the impacts of handling and release practices on Shortjaw Bonefish Albula glossodonta, a species of shallow‐water Pacific bonefish that supports a recreational fishery throughout its range and is emerging as recreationally important to the economy in Anaa Atoll, French Polynesia. We caught, released, and monitored the postrelease movements of Shortjaw Bonefish on the shallow flats of Anaa Atoll via recreational angling gear and small floats attached to the bonefish. Using Cox proportional hazards regression of our observations of PRP we tested how handling practices (air exposure) and release strategies (retained for a short period versus immediate release) influenced the probability of PRP. There was some evidence that air exposure increased susceptibility to PRP. However, retention in a recovery bag for 30 min did not reduce PRP. Actually, retention in the recovery bag increased the number of sharks in the release area after 30 min suggesting that Shortjaw Bonefish should be released quickly to avoid aggregating sharks. In both the handling and release practices components of the study, the number of sharks encountered proximate to the release site was the strongest predictor of PRP. Anglers and guides fishing in areas of high predator density such as at Anaa Atoll should release bonefish quickly to minimize aggregation of sharks that depredate released bonefish. Avoiding fishing flats with high predator densities and frequently rotating fishing flats may be necessary to quell PRP. Acknowledging risks and accounting for PRP and its contribution to overall postrelease mortality is essential for maintaining sustainable recreational fisheries for this species. Received August 17, 2016; accepted May 23, 2017Published online August 22, 2017

Life‐history characteristics of an exploited bonefishAlbula glossodontapopulation in a remote South Pacific atoll

“…Friedlander et al . () analysed the length frequency distribution of the A. glossodonta stock in Palmyra Atoll, which provides an estimate of natural mortality (0.27) in a virgin population at a Pacific atoll with high predator densities similar to that of Anaa Atoll (Lennox et al ., ). Given the uncertainty regarding the estimation of these parameters, historic failure of analogous fisheries and traditional ecological knowledge of the community citing significant declines in A. glossodonta abundance, we recommend the more conservative Hoenig () estimate of 0.21 for both sexes in the assessment of this population.…”

Length‐Based Assessment of an Artisanal Albulid Fishery in the South Pacific: a Data‐Limited Approach for Management and Conservation

“…; Lennox et al. ). Furthermore, owing to the nature of this spawning‐aggregation fishery in which bonefish are not vulnerable to capture until sexual maturity, the lower bound of the size limit is naturally enforced by the reproductive biology of the species.…”

“…To this aim, the establishment of a slot limit that protects both newly mature spawning females and megaspawners is a commonly utilized catch control in fisheries management (Froese 2004;Gwinn et al 2015). However, though theoretically effective, given the nature of the fishery where catches are brailed or netted from the traps in large quantities, we believe this solution will be hard to implement and there are many unanswered questions regarding the postrelease fate of these fish after interactions with humans (Coggins et al 2007;Lennox et al 2017). Furthermore, owing to the nature of this spawning-aggregation fishery in which bonefish are not vulnerable to capture until sexual maturity, the lower bound of the size limit is naturally enforced by the reproductive biology of the species.…”

Manual Acoustic Tracking Reveals the Spatial Ecology of Giant Trevally at a Remote South Pacific Atoll, with Implications for Their Management

“…Most giant trevally recreational fisheries adopt catch-and-release practices, but we know nothing about post-release survival rates beyond this study, in which all five animals survived. All of these fish were hooked in the corner of the jaw, suggesting fly-fishing may be a conservative way to effectively catch and release these fish, but our sample size is too small to make definitive conclusions and further research is needed to determine how factors such as gear type, hook placement, fight time, and the angler's treatment of the fish affect their survival rates (Cooke and Philipp 2004;Cooke and Cowx 2006;Danylchuk et al 2007;Lennox et al 2017). Numerous physiologic changes from increased exercise, air exposure and tissue damage as a result of interactions with fishing gear can result in mortality (Brownscombe et al 2013(Brownscombe et al , 2015.…”

“…Other predators at Tetiaroa that could potentially threaten the survival of caught and released giant trevally include blacktip reef sharks (Carcharhinus melanopterus) and lemon sharks (Negaprion acutidens). Lennox et al (2017) revealed that similar predator-rich coral atolls can yield high rates of post-release predation of fish released by recreational anglers, emphasizing the need for anglers to handle species with care and that these environments require more attention from catch-and-release science.…”