Distribution patterns of bottom trawl faunal assemblages in Porcupine bank: implications for Porcupine surveys stratification design.

• Main Authors: ICES, Velasco, Francisco, Serrano, Alberto
• Format: Report
• Language: unknown
• Published: ICES 2003
• Subjects: Pesquerías; Centro Oceanográfico de Santander; Porcupine Bank; North Atlantic; Northeast Atlantic
• Online Access: http://hdl.handle.net/10508/3399; http://hdl.handle.net/10261/327136

The distribution patterns of bottom trawl faunal assemblages in Porcupine bank is addressed using data from two bottom trawl surveys performed in the area. Hierarchical cluster analyses and canonical ordination analyses are applied respectively to define the different assemblages and to evaluate the main structuring environmental factors using information on depth, latitude, longitude, bottom temperature and salinity. Analyses are performed with two different matrices one in numbers of individuals per species in each haul and another in biomass of main commercial species in each haul. Three large assemblages are discriminated by hierarchical cluster analyses: shelf, outer-shelf and shelf-break, with some subgroups within each of them consistent in the results of both data matrices. Depth is the main structuring environmental factor in the area. Longitude has also an important effect on the bottom trawl assemblages distribution pattern, this effect is more likely to be related with relief structure and ground types differences in both sides of Porcupine bank. The original strata design used in Porcupine surveys, based on previous information on commercial catches, does not agree with the results of this study, but more information on the bathymetry in the area is needed to implement new bathymetric strata.