Depth trajectory and performance of a trawl used for an international bottom trawl survey in the Mediterranean
Bertrand, J.A.; Leonori, I.; Dremière, P.-Y.; Cosimi, G. (2002). Depth trajectory and performance of a trawl used for an international bottom trawl survey in the Mediterranean. Sci. Mar. (Barc.) 66(S2): 169-182. https://dx.doi.org/10.3989/scimar.2002.66s2169
In: Scientia Marina (Barcelona). Consejo Superior de Investigaciones Científicas. Institut de Ciènces del Mar: Barcelona. ISSN 0214-8358; e-ISSN 1886-8134
Also appears in:
Abelló, P.; Bertrand, J.A.; Gil de Sola, L.; Papaconstantinou, C.; Relini, G.; Souplet, A. (2002). Mediterranean marine demersal resources: the MEDITS international trawl survey (1994-1999). Scientia Marina (Barcelona), 66(S2). Institut de Ciències del Mar: Barcelona. 280 pp. https://dx.doi.org/10.3989/scimar.2002.66s2, more
An international bottom trawl survey (the MEDITS programme) has been carried out every year in the Mediterranean since 1994. During each survey, about 1000 hauls are done by a fleet of 8 to 11 vessels from 10 to 800 m depth, applying a unique standardized sampling protocol. This study analyses the trajectory and the performances of the sampling gear used for this survey, from records obtained during the surveys aboard some vessels in different geographical sub-areas and at different depth levels. Two kinds of sensors have been used, one to characterize a posteriori the vertical trajectory of the trawl from the beginning of shooting to the end of hauling (830 hauls), the other to describe in real time the stabilization of the trawl at its beginning (16 hauls) and its geometry during the tow (840 hauls). The results show the variability extent of these parameters linked with vessel, area, depth and period, illustrating their impact on the swept area estimates used for biological assessments. The results strongly suggest the inforcement of a quality strategy combining the use of rigourous sampling protocols and systematic controlling of the main parameters characterizing the trawl performance during routine surveys.
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