Journal of the Marine Biological Association of the UK



Research Article

Distribution and damage to the by-catch assemblages of the northern Irish Sea scallop dredge fisheries


L.O.  Veale a1c1 , A.S.  Hill a2 , S.J.  Hawkins a3 and A.R.  Brand a1
a1 University of Liverpool, Port Erin Marine Laboratory, Port Erin, Isle of Man, IM9 6JA, UK
a2 SEPA, Clearwater House, Heriot-Watt Research Park, Edinburgh, EH14 4AP, UK
a3 Marine Biological Association, The Laboratory, Citadel Hill, Plymouth, PL1 2PB, UK

Abstract

The major by-catch species retained during twice yearly dredge surveys of great scallop, Pecten maximus, and queen scallop, Aequipecten opercularis, (both Mollusca: Pectinidae) populations on 13 fishing grounds in the northern Irish Sea, over a period of five years, were identified and enumerated. Additionally, the damage sustained by the by-catch was assessed and related to a range of physical parameters recorded during the survey. A number of species captured in the spring-toothed dredges exhibited differences in abundance and damage sustained between years, and also between the start and end of the closed season for great scallop fishing (1 June–31 October). The by-catch assemblage varied geographically, dependent upon the underlying community structure, as well as putative factors including gear efficiency and substratum type. Two clear assemblage types were identified by multivariate analysis, one to the south-west of the Isle of Man, the other covering fishing grounds to the north, east and south of the island. There is a hierarchy of species sensitivity to damage in great and queen scallop dredges, probably related to morphological and behavioural characteristics. This selective mortality of a fraction of the community may have long-term implications at the ecosystem level. The degree of damage sustained by many species is related to both the volume of stones retained in the dredge, and the total volume of the catch (dredge fullness). If these were reduced, the overall magnitude of incidental by-catch mortality would be lower.

(Received September 4 2000)
(Accepted October 20 2000)


Correspondence:
c1 e-mail: lewis@liv.ac.uk