Selectivity of Oreochromis niloticus and O. aureus caught by trammel nets | ||||
| Egyptian Journal of Aquatic Biology and Fisheries | ||||
| Article 19, Volume 26, Issue 4, July and August 2022, Page 321-333 PDF (757.2 K) | ||||
| Document Type: Original Article | ||||
| DOI: 10.21608/ejabf.2022.249879 | ||||
 View on SCiNiTO | ||||
| Author | ||||
| El-Azab E. Badr El-Bokhty | ||||
| Abstract | ||||
| The present study is the first concerning commercial trammel net selectivity in El-Salam Canal. Selection ogives were estimated using Holt's method (1957) for both Oreochromis niloticus and Oreochromis aureus . L50 retention lengths of both species were estimated as 11.1-cm and 11.5-cm corresponding to the inner layer-mesh bar (2.15-cm) for the two species, respectively. With increasing the mesh bar to 2.65cm, L50 increased to reach 14.2 and 13.0cm in respective order for both species. The mean selection length calculated by Holt's method for Oreochromis niloticus increased from 11.97-cm (as opposed to the smaller mesh bar) to 14.76-cm (as opposed to the larger mesh bar). The same trend for O. aureus, the mean selection length increased from 11.64-cm to 14.34-cm in respective order also. Therefore, it's recommended to use a larger inner layer mesh bar length of 3 cm at least to gain extra weight and give more reproduction opportunities. | ||||
| Keywords | ||||
| El-Salam Canal; Trammel nets; Selectivity; Oreochromis niloticus; Oreochromis aureus | ||||
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