Publication Abstract

Spatial distributions (1989-2004) and preferential habitats of thornback ray and lesser-spotted dogfish in the Eastern English Channel

Spatial distributions (1989-2004) and preferential habitats of thornback ray and lesser-spotted dogfish in the Eastern English Channel

C.S. Martin, S. Vaz, B. Ernande, J.R. Ellis, P.D. Eastwood, F. Coppin, S. Harrop, G.J. Meaden and A. Carpentier

Thornback ray (Raja clavata) and lesser-spotted dogfish (Scyliorhinus canicula) are two of the most abundant demersal elasmobranchs occurring in the Eastern English Channel. R.clavata is commercially exploited, though S. canicula is of less commercial importance. As part of the CHARM project (http://charm.canterbury.ac.uk), Catch Per Unit Effort (CPUE) data for the period 1989-2004 were compiled from two annual, fishery-independent trawl

surveys that are undertaken in the Eastern English Channel (ICES Division VIId), the English Eastern Channel Beam Trawl Survey (ECBTS) and the French Channel Groundfish Survey (CGFS). Annual patterns in the relative abundance (number of fish per km²) of R. clavata and S. canicula were mapped, and seasonal and inter-annual variations examined. Quantile regression modelling was used to relate the relative abundance of both species to significant environmental factors (e.g. depth, seabed sediment type, bed shear stress, water temperature, salinity), and the resulting equation used to map habitat suitability using GIS. Observed patterns in relative abundance and model-derived suitable habitats were discussed in the light of a previous study that investigated the roles of both species as a structuring part of the

Eastern English Channel fish community. This works aimed to increase the scientific understanding of the spatial distribution of R. clavata and S. canicula, so that preferential habitats can be identified in order to facilitate improved management of these stocks. This is particularly relevant since the Eastern English Channel is subject to intense anthropogenic impacts in terms of shipping, aggregate extraction, tourism and both commercial and recreational fishing.

Reference:

C.S. Martin, S. Vaz, B. Ernande, J.R. Ellis, P.D. Eastwood, F. Coppin, S. Harrop, G.J. Meaden and A. Carpentier (2005) ICES Copenhagen. ICES CM 2005/N:23, 27pp.

C. S. Martin, S. Vaz, B. Ernande, J. R. Ellis*, P. D. Eastwood*, F. Coppin, S. Harrop, G. J. Meaden and A. Carpentier

ICES CM 2005/N:23, 27pp.