Quantifying Delayed Mortality from Barotrauma Impairment in Discarded Red Snapper Using Acoustic Telemetry

We tested the ability of venting and descender (recompression) devices to increase the relative survival of released Black Sea Bass Centropristis striata, a physoclistous reef species with high discard rates in hook‐and‐line fisheries that operate in the U.S. Atlantic Ocean and Gulf of Mexico. We caught fish via hook and line from waters that were 38 m deep, a depth where Black Sea Bass often exhibit signs of barotrauma and may be unable to submerge after release. Fish were conventionally tagged and vented with either an 11‐gauge cannula or a 16‐gauge needle, descended using a descender (recompression) device, or released as tagged controls (no venting or recompression). Tests of independence were used to determine the relationship between submergence and treatment (excluding recompressed fish) as well as between submergence and tag return rate. Tag‐recapture data were used to inform a Cox proportional hazards model that evaluated the survival of fish treated with each experimental device relative to the control group. A significantly greater proportion of fish submerged when treated with either venting device relative to the controls, and the fish that submerged had a greater proportion of tag returns relative to those that did not submerge. Venting and recompression increased postrelease survival compared with the controls. The results provide guidance to managers who seek methods to reduce discard mortality rates in hook‐and‐line fisheries for this important species. Future studies should examine the use of these devices at a range of depths to determine their effectiveness.

Section: Discussionmentioning

confidence: 99%

“…; Curtis et al. ), and Snowy Grouper Hyporthodus niveatus (Runde and Buckel ). Thus, the finding that recompression increases survival rates of Black Sea Bass reeled from relatively high pressures (approximately 5 atm) is not surprising.…”

Section: Discussionmentioning

confidence: 99%

Effectiveness of Venting and Descender Devices at Increasing Rates of Postrelease Survival of Black Sea Bass

Rudershausen

Runde

Buckel

2019

“…For example, the use of fish descending gear and venting tools increased the survival of released Red Snapper by 3.0 and 1.9 times, respectively (Curtis et al. ).…”

mentioning

confidence: 99%

Understanding Resource‐Conserving Behaviors Among Fishers: Barotrauma Mitigation and the Power of Subjective Norms in Florida's Reef Fisheries

Crandall

Garlock

Lorenzen

2018

Understanding the factors underlying fishers’ decisions to adopt resource‐conserving behaviors is important to successful fisheries management. This study used an online survey to explore factors motivating decisions to use alternative barotrauma mitigation measures (venting and descending) to improve discarded reef fish survival across recreational, charter, and commercial fishers in the state of Florida. A majority of respondents (66–69%) had experienced fish showing gross signs of barotrauma, and more than half of those (52–69%) reported using barotrauma mitigation most of the time when needed. Use of mitigation by other fishers was perceived to be lower (30–57%) and to have declined after removal of a venting tool requirement. Overall, respondents were more likely to have used venting tools (96–99%) than fish descenders (14–27%), and most respondents (81–86%) intended to use venting tools in the future. The theory of planned behavior was used to predict and explain intentions to use venting tools and/or fish descenders based on three variables: attitudes toward the method, subjective norms (i.e., social pressure), and perceived control (i.e., confidence in their ability to use the method). Fishers across sectors perceived venting tools and descenders to be similarly effective in improving released fish survival, but they felt that descenders were more time consuming, difficult to use, and expensive. Subjective norms and perceived control were stronger for venting tools than for descenders. Overall, subjective norms had the strongest influence on fishers’ intention to use either form of mitigation; attitudes and perceived control were also important in the case of descenders. Outreach efforts focusing on re‐enforcing subjective norms should have the greatest impact on increasing fishers’ use of barotrauma mitigation methods. Comparatively greater efforts are required to increase the use of descending gear than to increase the use of venting, and care should be taken to avoid strategies that could result in an overall decline of barotrauma mitigation.

“…Were predation explicitly accounted for (e.g., through tagging studies), increases to the estimates of fishing‐related mortality would be likely (Curtis et al. ) and the inferred effect of the recreational fishery would likewise increase. Given these unresolved issues, we echo the recommendation by Campbell et al.…”

Section: Discussionmentioning

confidence: 99%

Using Common Age Units to Communicate the Relative Catch of Red Snapper in Recreational, Commercial, and Shrimp Fisheries in the Gulf of Mexico

Putman¹,

Gallaway²

2020

The natural mortality rates and fecundity of Red Snapper Lutjanus campechanus vary substantially by age, so the age composition of catch is an important consideration when quantifying the relative effects of catch on the Red Snapper population across different fisheries. For example, the shrimp fishery catches many (but younger) Red Snapper, whereas directed commercial and recreational fisheries catch fewer (but older) individuals. We propose a simple approach for comparing catch across sectors. Fish that are caught can be scaled to a common age by multiplying or dividing by natural mortality rates so that the catch data can then be reported in “common age units.” Applying this approach to the catch data from the 2018 Red Snapper stock assessment, we showed that the shrimp‐trawl bycatch typically accounts for <10% of the relative catch, the commercial sectors account for ~32%, and the recreational sectors are responsible for ~59%. We believe that the effective management of Red Snapper requires regulation and oversight of each fishery that is proportional to its effect on the population. Given the apparently large influence of recreational fisheries on Red Snapper populations, recent management changes that delegate state‐by‐state control over important aspects of the recreational fishery (Amendment 50) should be accompanied by efforts to improve the understanding of this sector's interactions with Red Snapper.