R. FITRIANI*, R. HARTATI, S. SUNARYO, I. IRWANI, R. ARIO AND A. SOEGIANTO**
Departemen Ilmu Kelautan, Fakultas Perikanan dan Ilmu Kelautan, Universitas Diponegoro, Jl. Prof. Soedarto, SH. Kampus UNDIP Tembalang, Semarang 50275, Indonesia
*(e-mail : rahma.fitriani@outlook.com; Mobile : +6281295099971; **e-mail : agoes_soegianto@unair.ac.id; Mobile
: +6281335753862)
ABSTRACT
Tuna one of many landed commodities with important economic value in Pekalongan fishing port, Indonesia was caught using gill net, purse seine and mini purse seine. The purposes of this study were to determine
the growth, mortality, exploitation rate and the potential sustainability of Longtail Tuna (Thunnus tonggol) catches from the Java Sea. This research was conducted from October to December 2018 at Pekalongan
fishing port. Data analysis of growth and mortality was estimated using the FiSAT-II software and the surplus production model was applied to determine the maximum sustainable yield (MSY) and optimal efforts. Von Bertalanffy equation for length growth was fitted for length-at-age data to estimate L , K and t0. The results of this study showed that L , K and t0 were 56.18 cm FL, 0.62/year and -1.3373, respectively. Hence, the VBGF equation of Longtail Tuna in this study was Lt=56.18 (1-e[-0.62(t+1.3373)]). The total mortality rate (Z), natural mortality (M) and fishing mortality (F) were estimated as 2.39, 1.12 and 1.28/year, respectively, so the exploitation rate was estimated at 0.53. The maximum sustainable yield (MSY) and the optimal effort were 1,254.16 t/year and 457 trips/year, respectively. It showed that the exploitation status of Longtail Tuna resources in the Java Sea had been overfished.
Key words : Thunnus tonggol, growth parameters, mortality rates, maximum sustainable yield