Abstract |
Studies on the dynamics and exploitation pattern of Mullus barbatus (red mullet), Merluccius merluccius (hake), Serranus cabrilla (comber), eae Serranus hepatus (brown comber) fish stocks of Crete were realised by means of experimental trawl surveys carried out along the continental shelf and slope. Specifically, fishing was performed (a) on a seasonal basis, from summer 1988 until summer 1991, at 40 pre-defined stations (hauls) distributed in three depth zones (<70, 70-150 and 150-300m) all over the island and (b) on a monthly basis in the Iraklion bay during the years 1991-1993. Growth and mortality parameters were estimated and the state of the stocks was assessed through the application of the analytical model of Beverton and Holt. The temporal and spatial biomass and abundance fluctuations were also determined. All stocks, except that of M. barbatus, were found to be overexploited but they seem to be on a stable condition. Exploitation of M. barbatus stock was closed to the recommended by the analytical model F0.1 level. Bigger M. merluccius individuals were suffering lower fishing mortality due to their movement in deeper areas outside the fishing grounds exploited by the commercial trawlers. Red mullet was the most abundant of the examined species and together with comber and brown comber were distributed in the two more shallow zones. Recruitment of the above species occurs during late summer and early winter months mainly in depths less than 70m. Hake was found in all depth zones and recruitment was observed throughout the year with a peak in June. It has been suggested that a reduction of about 20% of the fishing mortality accompanied by a small increase (e.g. at 20mm) of the mesh-size of the trawl's cod-end would lead to a rational management of the stocks.
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