Research Document - 2010/058

Spatial Analysis of Coral and Sponge Densities with Associated Fishing Effort in Proximity to Hatton Basin (NAFO Divisions 2G-0B)

By V.E. Wareham, L.M.N. Ollerhead and K. Gilkinson

Abstract

A national Canadian Science Advisory Secretariat (CSAS) science advisory process was called (March 9-12, 2010) to aid in advancing Canada’s domestic and international commitments to manage impacts of fishing on sensitive benthic areas. A fundamental piece of information which is necessary to begin addressing questions of conservation of corals and sponges is their distribution in Canadian waters and the distribution and extent of ‘significant’ concentrations (= areas) of corals and sponges. The following Newfoundland and Labrador Region contribution focuses on an area in Hatton Basin in the Northwest Atlantic. The rational for selecting this study area was due to the location of important coral and sponge concentrations identified in earlier studies. In addition, the area is recognized as an area of high coral and sponge by-catch by the fishing industry which led to a voluntary industry closure to fishing in 2007.

Data on coral and sponge biomass and species richness were collected from by-catch records taken during the Northern Shrimp Stock Assessment Survey (2005-2008) and Groundfish Stock Assessment Surveys (1996-1999). The Northern Shrimp Stock Assessment Survey was used to model densities of corals and sponges, species richness, and to provide information on location of unsuccessful sets as a result of trawl net tear-ups which may be interpreted as an index of rough, hard ocean floor terrain, and therefore, possible prime coral habitat. Coral species were grouped into conservation units (bins) based on similar morphologies and life histories (growth rates and longevity).

A GIS-based density analysis was used to calculate and map the spatial distribution of areas of significant coral and sponge catches in NAFO divisions 2G-0B from the various surveys that took place between 2005 and 2008 and recorded data from 974 fishing sets. Data was modeled using the methodology from Kenchington et.al. (2009). Using these methods, density analysis was used to calculate and map the significant areas of corals and sponges based on biomass and areas of species richness. Commercial fisheries log book data was used as a coarse index of fishing effort through a specific time period (1998-2009) by fishery, and gear types based on recorded locations of fishing activities. The spatial distribution of fishing effort was coarsely compared with the distribution of significant areas of corals and sponges. The location and trends in distribution of significant areas of conservation units, i.e. coral and sponge groupings are discussed.

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