Distribution of deep-water corals, sponges, and demersal fisheries landings in Southern California, USA: implications for conservation priorities.

Enrique J Salgado,Peter J Etnoyer,Stephanie E Nehasil

doi:10.7717/peerj.5697

Abstract

Deep-sea corals in Southern California are diverse and abundant but subject to multiple stressors, including bottom-contact fisheries using mobile and fixed gear. There is a need for more information on the distribution of these taxa in relation to the distribution of demersal fishing effort, and the distribution of marine protected areas, in order to improve spatial planning. There are many marine managed areas in Southern California, including essential fish habitat (EFH) areas, conservation areas, and a national marine sanctuary, but specific areas of overlap between bottom fishing and benthic epifauna are poorly known. Groundfish surveys were conducted by the National Marine Fisheries Service using a remotely operated vehicle throughout Southern California between 2003 and 2011 to document abundance and distribution of deep-water rockfish and flatfish to a depth of 500 m. Corals and sponges were also common in these images, providing an opportunity to examine these communities. Analyses of 34,792 still images revealed abundance and diversity of coral and sponge taxa, as well as frequency of fishing debris. The occurrence data were overlaid in a geographic information system with landings data for deep-water (>50 m) demersal fisheries to identify areas of spatial overlap. Corals or sponges were observed in 23% of images. A total of 15 coral genera and six sponge morphotypes were identified. A total of 70 species codes were targeted by deep-water demersal fisheries operating below 50 m for years 2007–2011. A novel priority-setting algorithm was developed to identify areas of high richness, abundance, and fishing intensity (RAFi). Several highly-ranked areas were already protected as EFH (Footprint, Piggy Bank). Other highly-ranked sites (West Catalina Island, San Clemente Island, 9-Mile Bank, Santa Rosa Flats) were encompassed by transient gear restrictions, such as Rockfish conservation areas, but are now recommended for permanent protection by the Pacific Fishery Management Council.

Highlights

Deep-water (>50 m) azooxanthellate coral and sponge communities are widespread in the Northeast Pacific, from the Bering Sea west to the Hawaiian Islands and south to the tip of Baja California (Verrill, 1870; Ostarello, 1973)
Other records come from telepresence expeditions using remotely operated vehicles (ROVs) and incidental bycatch in commercial fisheries. These records are compiled through NOAA’s National Database of Deep-Sea Corals (NOAA, 2017), but to date there has been no synthesis of these occurrences in relation to fisheries landings in the Southern California Bight (SCB), such as the analysis provided here
In terms of geographic overlap, these results show that mobile gear has a relatively small footprint in the SCB compared to fixed gear, and there is considerable overlap between fisheries landings and the occurrence of corals and sponges for both mobile and fixed gear

Summary

Introduction

Deep-water (>50 m) azooxanthellate coral and sponge communities are widespread in the Northeast Pacific, from the Bering Sea west to the Hawaiian Islands and south to the tip of Baja California (Verrill, 1870; Ostarello, 1973). In this region, deep-water coral species are reported from 50 to 3,880 m, but are most abundant between 50 and 1,000 m (Etnoyer & Morgan, 2005). Several new, undescribed species of carnivorous sponges (Reiswig & Lee, 2007) and gorgonians (Etnoyer, 2008; Williams, 2013) were recently discovered using remotely operated vehicles (ROVs)

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