In situ target strength measurements. Preliminary data of sardine (Sardina pilchardus W.) from the Mediterranean Sea

During the pelagic fishing stations of the acoustics surveys Ecomed 91 and Ecomed 92, carried out in november 1991 and 92, series on sardine TS were collected using a SIMRAD EK-500 38 kHz split-beam echo sounder and echointegrator. Only data with similar features in bottom depth, trawling depth and % of capture were used. The Least-Mean-Square regression of mean TS on the logarithm of the mean fish length of the form TS=m1og(1}+b was finally applied to 11 data series giving m=29.73 and b=-74.08 with r =0.94 or, requiring that m=20, b=-63.34, which is higher than ot~ers to similars species but close to the Love's one. This could be explained for the trawling depth or for the short range of length analyzed