The Dundalk Cockle Cerastoderma edule Fishery in 2003-2004

Abstract

A cockle fishery in Dundalk Bay has been infrequently documented since 1970. Cockle bearing sands and muds are 44.5 km2 in extent. The bay, which is in an SPA and a cSAC also supports large numbers of overwintering birds, of particular relevance is the oystercatcher (Haematopus ostralegus). In 2003 and 2004 when an assessment of the fishery was undertaken, cockles ranged from 0 to 8+ years of age, but the vast majority were 0 and 1+ animals. Growth was rapid and 53% of asymptotic length (49.1 mm) was achieved at the first winter. In agreement with observations elsewhere, the density of the rapidly growing animals was very low. The estimated cockle biomass in spring 2004 was 1,654 tonnes comprising 143 million animals. A survey undertaken in spring 2004, suggested that spat falls contributing to the population may not have been evenly distributed throughout the Bay. Condition factor in 2003 and 2004 did not conform to an expected seasonal pattern, suggesting that some parts of the area supported better growth rates than others. Cockle landings from this fishery are of good quality. Cockle size is at the upper end of the range in Britain and Ireland and the majority of individuals landed by suction dredging were 1+ years old. Raked landings contained more 2+ cockles than suction-dredged ones. Damage to cockles discarded by suction dredging followed the pattern reported elsewhere and damage rates increased with the size of the animals. Some cockle landings have probably always been made in Dundalk Bay by picking and raking, but 2001 marked the beginning of an expansion of the dredge fishery, whose landings exceeded 200 tonnes in 2004. The necessity for controls and management of this fishery in the context of EU legislation and particularly within the constraints of the Habitats Directive is briefly examined.