Authors: Düzbastilar, F. Ozan; Özgül, Aytaç; Aydin, İlker; Gül, Benal; Soykan, Ozan

Source: Acta Ichthyologica Et Piscatoria, Volume 40, Number 1, June 2010 , pp. 27-36(10)

Publisher: Acta Ichthyologica et Piscatoria

Abstract:

Background. Poor selectivity of trawl cod-ends has been a major problem of the modern-day fisheries, contributing to destruction of non-target organisms. It is expected that increased trawl selectivity can reduce bycatch and discards. This would only be true if significant numbers of the escaping fishes survive. The chances of survival of many species after escaping the trawl cod-end are still poorly known. This study was aimed at providing mortality estimates of brown comber, Serranus hepatus, escaping from two different demersal trawl cod-ends (40 mm diamond and square) in the Aegean Sea. We also looked at possible seasonal variation in the survival rate of escaped brown comber (diamond mesh).

Materials and Methods. Two experiments were conducted off the Yassıca Island, Izmir Bay (Aegean Sea, Turkish coast): in winter 2007 and summer 2008. Five hauls were performed in winter (January February 2007), and nine hauls in late summer (September 2008). Sampling time was 15 min, except for a control cage in 2007 experiments.

Results. No significant difference in the mortality of brown comber for 40 mm diamond mesh cod-end was demonstrated between the winter (2.2 percentage points) and the summer (1.9 percentage points). Throughout each period of this experiment, the survival of escaping brown comber showed a length-dependent mortality, with the majority of dead fish being less than 8.8 and 9.4 cm in length for diamond and square test cages, respectively. The experiments carried out in 2008 demonstrated that the survival of brown comber for diamond and square test cages was generally very high (98.1 and 82.9, respectively).

Conclusion. The escape mortality of brown comber was negligible for two different cod-ends and seasons.

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Keywords: BROWN COMBER; SERRANUS HEPATUS; BENEKLI HANI; ESCAPE MORTALITY; DIAMOND COD-END; SQUARE COD-END; SEASONAL VARIATION

Document Type: Research article

DOI: http://dx.doi.org/10.3750/AIP2010.40.1.04

Publication date: 2010-06-01

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• ACTA ICHTHYOLOGICA ET PISCATORIA (AI&P) is an international, peer-review scientific journal that publishes articles based on original experimental data or experimental methods, or new analyses of already existing data, in any aspect of ichthyology and fisheries (fin-fish only).
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