Spatial assessment of albatrosses, commercial fisheries, and bycatch incidents on Canada’s Pacific coast

Ch Fox,Kh Morgan,Pd O’Hara,R Tadey,C Robertson

doi:10.3354/meps13783

Abstract

Fisheries bycatch mortality poses a primary threat to the majority of the world’s 22 albatross species, 15 of which are at risk of extinction. Although quantitative estimates of albatross bycatch are often unavailable due to a relative or total absence of monitoring, spatial overlap between fisheries and albatrosses is often used to estimate the extent of interaction, a proxy for exposure to bycatch, and to inform avoidance and mitigation actions. Using comprehensive records of commercial demersal longline and trap fishing and survey information for albatrosses (black-footed albatross Phoebastria nigripes, Laysan albatross P. immutabilis, short-tailed albatross P. albatrus), the extent of spatial potential interaction was estimated in Canada’s Pacific coast waters and examined across breeding and non-breeding seasons. The distributions of albatrosses and longline and trap fisheries were found to substantially overlap, with potential interaction hotspots concentrated along the continental shelf break. Trap fisheries reported 1 albatross bycatch incident, suggesting that these fisheries are responsible for negligible albatross mortalities. In contrast, >80% of recorded albatross bycatch incidents occurred within 10 km of albatross-longline fisheries hotspot locations, providing evidence that longline-albatross potential interaction hotspots represent actual areas of elevated bycatch mortality risk. Indicative of potential conservation concern, 60% of short-tailed albatross sightings occurred within 10 km, and 93% within 30 km, of longline-albatross potential interaction hotspots. By contributing knowledge regarding albatross-fisheries interactions, in addition to undertaking the first evaluation of albatross-fisheries hotspots with recorded bycatch incidents on Canada’s Pacific coast, this study represents a step towards enhancing albatross conservation through bycatch avoidance and mitigation.

Highlights

The world’s oceans, of critical importance to global nutrient cycles, climate regulation, biodiversity, and socio-economic systems, have been fundamentally altered by humans (Jackson et al 2001)
We further examine the utility of our approach by comparing potential interaction hotspot locations with locations of actual reported catches of albatrosses in longline or trap fisheries
Relative to the breeding schedule of albatrosses, longline fishing effort of the potential interaction hotspots was slightly larger during the breeding season (2794 km2) than during the non-breeding season (2514 km2; Table 2)

Summary

Introduction

The world’s oceans, of critical importance to global nutrient cycles, climate regulation, biodiversity, and socio-economic systems, have been fundamentally altered by humans (Jackson et al 2001). Considerable progress has been achieved in the development and implementation of modified gear and fishing practices to reduce the incidental take of non-target taxa (e.g. Hall & Mainprize 2005, Anderson et al 2011, Senko et al 2014, Domingo et al 2017) Despite this progress, bycatch remains a significant driver of seabird, cetacean, and turtle population declines and recovery failures, and directly threatens the persistence of numerous species worldwide (e.g. multiple albatross species: Arnold et al 2006, Jiménez et al 2014, Bakker et al 2018; North Atlantic right whale Eubalaena glacialis: Knowlton et al 2012; vaquita Phocoena sinus: Taylor et al 2017; leatherback turtle Dermochelys coriacea: Roe et al 2014)

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Discussion

Conclusion