Domingos M.M., Dantas D.V. 2019. Proposed bycatch-reduction modifications of shrimp fyke nets used in South American lagoons. Acta Ichthyol. Piscat. 49 (1): 1-7.Background. Shrimp fisheries using fyke nets have been associated with a massive acquisition of teleost fishes as bycatch, potentially resulting in the decimation of their stocks. Based on this assumption, the presently reported study intended to test an alternative modification of a commonly used fyke net, in order to minimize the impact of its low selectivity. Materials and methods. To evaluate the alternative design proposed in this work, a total of 44 sampling efforts, including 22 with a control gear (CG) and 22 with a modified gear (MG), were conducted at a subtropical coastal lagoon system located in southern Brazil. In all trials, the fyke nets were installed at the fishing area approximately at 18:00 h and removed approximately at 06:00 h. The duration of each trial was nearly 12 h, which was similar to the catching time preferred by local fishermen. Results. Bycatch (BC) was preponderant in both modalities but the results showed that MG presented a reduction by 66 percentage points in BC catches, being more selective than CG. Additionally, the non-parametric test showed no significant differences of shrimp catches between the fishing gears used (MG and CG). So, the tested bycatch reduction devices (BRD) reduced the bony fishes acquisition preserving the volume of the target catch. Conclusion. The vertical opening reduction due the adoption of guiding panel + fan upper panel contributed to bycatch reduction, being a consistent BRD to reduce the potential impacts of this fishing gear over the bony fishes stocks.
Shrimp trawls are one of the main bycatch generators in artisanal fisheries. Our work evaluated the adoption of low cost devices for artisanal bottom trawling to reduce bycatch assimilation and improve shrimp catches. To evaluate the proposed changes, we evaluated the performance of four different trawl gears from May to July 2015 in Pinheira Beach, Brazil. The hauls were divided into four treatments as follows: (1) hauls with unmodified control gear, (2) hauls with gear that included the kite escape device (KED), (3) hauls with gear that included long sweeps, and (4) hauls with gear that included both the KED and long sweeps. The second trawling group (2) showed the highest reduction in bycatch for all trawl gears. Additionally, all hauls that included the KED and/or long sweeps had improved shrimp catches during the study compared with trawl nets without the KED. During the hauls with KEDs we got the best shrimp‐to‐bycatch proportion (1:8.9). The modifications proposed can improve trawl gear selectivity while maintaining the shrimp catches.
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