Abstract
Increasing post-release survival of discarded fishes is a critical challenge to the development of effective conservation and management strategies. Among reef fishes, this challenge is further complicated by pressure-related injuries known as barotrauma. To address this, US fishery management agencies are enacting rules requiring fishers to possess descender devices onboard their vessels for barotrauma mitigation purposes. However, requiring possession of descender devices does not guarantee their use. Consequently, any benefits resulting from these regulations rely completely on fishers embracing the use of descender devices. In spite of this, fishers are questioning the survival of fishes released using these devices, claiming that this scenario provides easy opportunities for depredation. If resource managers are to promote descender devices as best practices, they must proactively address fisher concerns about depredation of fishes during descent. To examine if the use of descender devices increases opportunities for depredation, we investigated two disparate fishery-independent camera datasets from the Alabama Artificial Reef Zone in the northern Gulf of Mexico. The first dataset is from a vertical longline survey, and the second is from a mark-recapture study. Both gears were equipped with downward-facing GoProTM cameras, which allowed the fate of fishes from capture to landing (on the vertical longline) and from surface to bottom release (on hook-and-line) to be recorded. Between 2016 and 2018, GoProTM video footage was collected from 1483 vertical longline sets and 1096 descender releases. During vertical longline sampling, 54 depredation events were recorded, whereas none were recorded during descender releases. While far from a controlled study, this opportunistic comparison of ascending fishes on vertical longline and descending fishes on descender devices indicates that fishes on descender devices are substantially less prone to depredation – a finding that could ultimately promote the use of descender devices by stakeholders.
