Growth and Mortality, Recruitment and Exploitation Rate of Fringescale Sardinella Sardinella fimbriata (Valenciennes 1847) in Rote Island in the Savu Sea

Abstract

Fringescale sardinella is one of the largest fishery resources and has the highest economic value in the Savu Sea. The increasing demand for this fish makes it one of the main fishing targets, which allows overfishing to occur. Therefore, the purpose of this study was to determine the population dynamics of sardinella fringescale through growth and mortality, recruitment and exploitation rate of fringescale sardinella in Rote Island in the Savu Sea.

A total of 1095 fish sampled from Rote Island were assessed and showed the total length (TL) range from 90 mm to 157 mm. Further, the data were analyzed using FISAT II software with the following results: the length-weight relationship was W= 0.0004L^2.2523, while the negative allometric growth pattern and growth equation was Lt = 165.26 (1 - exp^{1,500 (t + 0.0585)}).

The age of S. fimbriata consisted of 1-2 cohorts. Recruitment of S. fimbriata in Rote Island occurred throughout the year with the highest peaks in May and August. The size of the first caught fish (Lc) was 96.98 mm TL. The total mortality rate (Z) was 2.41 yr^-1, natural mortality (M) was 1.45 yr^-1 and fishing mortality (F) was 0.97 yr^-1. The exploitation rate of S. fimbriata is estimated at 0.40 yr^-1; this implies that the stock does not exceed the optimum exploitation rate (E = 0.5) or that overfishing has not occurred in the Savu Sea. Nevertheless, this study’s results are sufficiently robust to anticipate that the unprecedented overexploitation of S. fimbriata in Rote Island has nearly occurred. Therefore, regular monitoring and surveillance of surface gillnet fishing gear are urgently needed.