Elasmobranch bycatch in US West Coast groundfish fisheries

Je Jannot,J Mcveigh,R Bjorkland,Vj Tuttle,T Mitchell,Ka Somers

doi:10.3354/esr01121

Abstract

Effective management of multispecies fisheries in large marine ecosystems is challenging. To deal with these challenges, fisheries managers are moving toward ecosystem-based fishery management (EBFM). Despite this shift, many species remain outside protective legislation or fishery management plans. How do species that fall outside of formal management structures respond to changes in fisheries management strategies? In 2011, the US West Coast Groundfish Fishery (WCGF) shifted management to an Individual Fishing Quota (IFQ) program. We used data collected by fisheries observers to examine the impact of this shift on elasmobranch catch (sharks, skates, rays). Historically, not all elasmobranchs were included in the WCGF Management Plan, making them vulnerable to fishing mortality. We grouped elasmobranchs into 8 groups based on 14 ecomorphotypes to examine relative catch within groundfish fishing sectors during the period 2002-2014. Of the 22 sharks and 18 skates and rays that these fisheries capture, 9 are listed as Near Threatened or greater on the IUCN Red List and 10 species are listed as Data Deficient by IUCN. The bycatch of 4 non-managed elasmobranch species was reduced under the IFQ program; IFQ management had no significant impact on the remaining 27 species caught by the IFQ fleet. Overall, catch of non-managed elasmobranchs was relatively low. We show that groups of ecomorphotypes co-occur within fisheries, suggesting natural management units for use in EBFM. This work helps identify gaps in monitoring and assessing the impact of management and policy on elasmobranch populations.

Highlights

In the last 20 yr, fisheries science has moved away from single-species approaches to management toward ecosystem-based fisheries management (EBFM), which incorporates ecological processes and components that have historically been left out of fisheries management (Link 2002, 2010, Latour et al 2003)
To place our results in the context of global elasmobranch bycatch, we describe the diversity of elasmobranchs that interact with the West Coast Groundfish Fishery (WCGF) and identify species of concern, estimate incidental catch on those elasmobranch species not actively managed by the current West Coast Groundfish Fishery Management Plan (WCGFMP) (PFMC 2019), and examine trends in non-managed elasmobranch catch across time and fishery sectors
WCGF non-managed elasmobranch bycatch belonged to 14 ecomorphotypes and 8 broad groups (Table 1)

Summary

Introduction

In the last 20 yr, fisheries science has moved away from single-species approaches to management toward ecosystem-based fisheries management (EBFM), which incorporates ecological processes and components that have historically been left out of fisheries management (Link 2002, 2010, Latour et al 2003). EBFM fosters a greater consideration of all components of marine ecosystems affected by fishing activity, including non-target species and associated habitats. An on-going challenge of sustainable EBFM is the incidental catch of non-target species, or bycatch. Evidence collected in recent years indicates that elasmobranchs (sharks, skates, rays) might be susceptible to over-harvesting and bycatch in marine fisheries Stevens et al (2000) estimated that almost 50% of global chondrichthyan catch (elasmobranchs and chimaeras) was non-targeted bycatch Recent estimates indicate that global shark removals may be in the tens of millions of individuals annually (Clarke et al 2006, Crowder et al 2008, Oliver et al 2015, James et al 2016). Stevens et al (2000) estimated that almost 50% of global chondrichthyan catch (elasmobranchs and chimaeras) was non-targeted bycatch

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