Management parameters and gillnet selectivity of blacktip sea catfish Plicofollis dussumieri (Valenciennes, 1840) to support sustainable fishery management in the Oman Sea

Plicofollis dussumieri (Valenciennes, 1840) is a commercially important fish species that is caught using gillnets in the Oman Sea. However, the lack of standard gillnets with a suitable mesh size has resulted in damage to the stocks of this species and a high number of undersized fish being caught each year. In this regard, the selectivity of gillnets for P. dussumieri was studied from December to March 2021. Four commercial gillnets with mesh sizes of 4.8, 6.3, 10.0, and 15.3 cm were used in this study to find the best mesh size. A total of 818 specimens were caught during the experiment. The SELECT method was applied to fit four different gillnet selectivity models. The bi-normal curve yielded the lowest model deviance and was judged to provide the best fit to the data. The mean length ±SE was estimated as 34.13±0.41, 36.93±0.44, 38.74±0.33 and 42.7±0.44 cm for 4.8, 6.3, 10.0 and 15.3 cm mesh sizes, respectively. The size of P. dussumieri at first maturity was determined to be 32.3 cm. The results of the Kolmogorov-Smirnov (K-S) test of the length frequency of P. dussumieri species caught with different mesh sizes showed that there is a significant difference between the 4.8 and 15.3 cm mesh sizes (p<0.05). The findings of the study showed that there would be no threat of recruitment overfishing of P. dussumieri in the event of the introduction of gillnets with a mesh size of 10.0 cm for commercial fishing. Keywords: Gillnet, Mesh selectivity, Plicofollis dussumieri, SELECT method, Stock management, Oman Sea