Trawl selectivity trials on the deep-water rose shrimp (Parapenaeus longirostris) in Sicilian waters

• Published in: Hydrobiologia 2006-03, Vol.557 (1), p.113-119
• Main Authors: RAGONESE, S, BIANCHINI, M. L
• Format: Article
• Language: English
• Subjects: Animal and plant ecology; Animal, plant and microbial ecology; Biological and medical sciences; Crustacea; Crustaceans; Deep water; Fisheries management; Fishing; Fundamental and applied biological sciences. Psychology; General aspects; Invertebrates; Marine; Marine biology; Parapenaeus longirostris; Retention; Straits; Synecology
• ISSN: 0018-8158; 1573-5117
• DOI: 10.1007/s10750-005-1314-y

Issue Title: Theme Issues of Decapod Crustacean Biology: Proceedings of the 8th Colloquium Crustacea Decapoda Mediterranea, held at the Ionian University, Corfu Isl., Greece, 2-6 September 2002, and organized by the University of Athens, Greece The selectivity of the traditional commercial bottom trawl net employed in Sicily to catch the Mediterranean deep-water rose shrimp, Parapenaeus longirostris, has been assessed. Two fishing campaigns were carried out in the Strait of Sicily and in the Southern Tyrrhenian Sea, using the covered cod-end method (mesh 20 mm vs. 31 mm). Of a total catch of 11,601 individuals, 23.4% escaped in the cover; the sample length structure from the Strait is unimodal, while that from the Tyrrhenian, polymodal. A logistic curve, fitted with a maximum likelihood criterion, has been used to model the selectivity data, in order to obtain the parameters CL^sub c50%^ (50% retention size), SR^sub 75-25%^ (selection range) and SF (selection factor, i.e. CL^sub c50%^/mesh). The two sets of data, besides a larger selection range for the Strait sample (5.2 mm vs. 2.3 mm), produced very similar estimates (retention sizes of 13.0 mm vs. 12.8 mm CL), fitting the logistic curve well. Almost no shrimp larger than 20 mm does escape from the cod-end; moreover, from the amount of damaged specimens found in the cover, even the evaded shrimps sustain a high fishing mortality. An increase of the present cod-end mesh opening, even above the size required by the EU bylaws (at present, 40 mm stretched) seems necessary for managing the fishery.[PUBLICATION ABSTRACT]