Selectivity of square and hexagonal mesh codends for the deep water rose shrimp, Parapenaeus longirostris (Lucas, 1846) (Decapoda, Penaeidae) in the Aegean Sea

This study aims to assess the selectivity of square and hexagonal mesh codends for the deep water rose shrimp, Parapenaeus longirostris. Experiments were conducted in Kuşadasi Bay and Sigacik Bay, eastern Aegean Sea, between 30 September and 25 October 2007 with a commercial stern trawler. The covered codend technique was used for controlling the escapees and selectivity parameters were estimated by maximum likelihood over a logistic model. The selectivity parameters for individual hauls were estimated using the software CC2000, whereas mean selection curves of the codends were estimated by using Fryer's model, taking into account the between-haul variation using the ECModeller software. The mean fifty percent retention length (L50) values of square and hexagonal mesh codends were estimated as 16.7 mm ± 0.07 and 17.4 mm ± 0.05, respectively. Selection range (SR) values were 6.5 mm ± 0.11 in square and 6.2 mm ± 0.15 in hexagonal mesh codend. Although L50 and SR values of the two different mesh shape codends are close to one another, L50 values of neither codend provides a satisfactory selection, considering the 21 mm length at first maturity (LFM) of this species. However, the hexagonal mesh codend can be used as an alternative for the same mesh size diamond mesh codend in targeted rose shrimp trawl fishery. © 2009 Brill Academic Publishers.