Scientia Marina, Vol 71, No 1 (2007)

Comparison of the catches of European hake (Merluccius merluccius, L. 1758) taken with experimental gillnets of different mesh sizes in the northern Tyrrhenian Sea (western Mediterranean)


https://doi.org/10.3989/scimar.2007.71n147

Mario Sbrana
Centro Interuniversitario di Biologia Marina ed Ecologia Applicata, Livorno, Italy

Paola Belcari
Dipartimento di Scienze dell’Uomo e dell’Ambiente, Prisa, Italy

Stefano de Ranieri
Centro Interuniversitario di Biologia Marina ed Ecologia Applicata, Livorno, Italy

Paolo Sartor
Centro Interuniversitario di Biologia Marina ed Ecologia Applicata, Livorno, Italy

Claudio Viva
Dipartimento di Scienze dell’Uomo e dell’Ambiente, Prisa, Italy

Abstract


The impact of the gillnet fishery on Merluccius merluccius (European hake) was investigated in the northern Tyrrhenian Sea, western Mediterranean. Four mesh sizes were tested: 53, 62.5, 70 and 82 mm. Horse mackerel (Trachurus trachurus), hake and tub gurnard (Chelidonichthys lucerna) dominated the catches, from a minimum of 89% (82 mm mesh) to a maximum of 97.8% (70 mm) of the biomass caught. Efficiency of the four meshes was not significantly different with respect to the total hake catches. Selectivity on M. merluccius was assessed by Sechin and SELECT methods. Tangling was an important catch modality for hake, as evidenced by the results of the Sechin model which described only the first mode of the size distributions corresponding to the entangled specimens. SELECT showed that the bi-modal function gave the best adjustment to the length-frequency distributions; the modal catch sizes were 33, 39.2, 43.6 and 51 cm total length respectively for the 53, 62.5, 70 and 82 mm mesh sizes. Taking into account the size of first maturity for females (35.1 cm TL), 62.5 mm is the most adequate mesh for exploiting hake as it gives some protection to both immature specimens and large females.


Keywords


European hake; gillnet; selectivity; Sechin method; SELECT method; western Mediterranean; artisanal fishery

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