The Effects of Scallop Dredge Fishing Practices on Physical, Behavioral, and Physiological Stress in Discarded Yellowtail Flounder, Windowpane, and Fourspot Flounder

Brooke N Anderson,Amelia M Weissman,James A Sulikowski,David B Rudders,John Mandelman

doi:10.1002/mcf2.10139

Abstract

AbstractThe Atlantic sea scallop Placopecten magellanicus dredge fishery is one of the most lucrative commercial fishing industries in the northeastern United States, and fish bycatch can comprise up to ~42% of the total catch. Benthic species, such as flatfish, are particularly susceptible to unintended capture in scallop dredge gear, and mitigating bycatch and associated mortality has been mandated a priority for fisheries management. Based on this management need, the present study evaluated the physical, physiological, and behavioral stress responses of Yellowtail Flounder Limanda ferruginea, Windowpane Scophthalmus aquosus, and Fourspot Flounder Paralichthys oblongus to capture in the scallop dredge fishery. More specifically, we used generalized additive models and linear regression models to assess the influence of various fishing practices, environmental conditions, and biological factors on injury condition, physiological parameters, and reflex indicators. Although these flatfish species appeared to be physically resilient to capture based on an observable injury assessment, dredge capture and handling factors proved stressful, with the degree of immediate mortality, physiological disturbances, and reflex impairment varying by species. While multiple factors influenced the degree of stress in these species, based on our results the reduction of tow duration and limiting air exposure/sorting duration would likely be the most effective strategies to mitigate the impact of scallop dredge fishing on these flatfish species.

Highlights

The incidental capture of nontargeted organisms, referred to as bycatch, is one of the most pressing threats to the world’s fish stocks (e.g., Davies et al 2009)
Conservative 90% mortality rates are assumed for Windowpane (WP) Scophthalmus aquosus and Yellowtail Flounder (YT) Limanda ferruginea (Grothues et al 2017) due to overfished stock statuses (NEFSC 2015), but total mortality has never been formally evaluated for these species in the scallop dredge fishery
The current study evaluated the physical, physiological, and behavioral stress responses of YT, WP, and Fourspot Flounder (FS) Paralichthys oblongus to capture and handling in the scallop dredge fishery

Summary

Introduction

The incidental capture of nontargeted organisms, referred to as bycatch, is one of the most pressing threats to the world’s fish stocks (e.g., Davies et al 2009). Fishing capture and handling can cause physical injury, physiological and behavioral perturbations, and unobserved postrelease mortality in discarded fish (e.g., Davis 2002) As such, evaluating these often species-specific responses to capture and handling is necessary to establish or refine management measures enabling overexploited stocks to rebuild (Beardsall et al 2013). Despite the susceptibility to capture and management concern for YT and WP, no studies to date have investigated the effects (i.e., stress, mortality) of scallop dredge fishing capture on any flatfish species Based on this need, the current study evaluated the physical, physiological, and behavioral stress responses of YT, WP, and Fourspot Flounder (FS) Paralichthys oblongus to capture and handling in the scallop dredge fishery. Our results are intended to provide considerations for reducing the impact of the scallop dredge fishery on these flatfish bycatch species

Methods

Results

Discussion

Conclusion