Dampak Hidrodinamika Terhadap Sebaran Daerah Penangkapan Tenggiri Batang (Scomberomorus commerson) di Perairan Kepulauan Riau

Abstract

Narrow-barred Spanish mackerel (Scomberomorus commerson) is an exportable fish captured by gillnet fishing fleets from Bintan Regency. The fleets are operated in the Kepulauan Riau waters but information on their activities is limited. Such information is important to the institution the Agency for Marine and Fisheries Affairs of Archipelagic Riau Province for ensuring the sustainability of the fisheries from both economic and biological perspectives. This study aims to determine the spatial-temporal distributions of the mackerel fishing grounds along the year with reference to the capture data, sea surface temperatures, chlorophyll-a concentrations, and salinities in the last 4 months of 2022. This study analyzed data from a fish export company PT AK and Bintan Intan Gemilang (BIG), Pengawasan Sumber Daya Kelautan Perikanan (PSDKP) office at Tanjungpinang, Bintan, interviews of fishers affiliated with 44 fishing boat samples, and satellite-based marine data. Analysis on the simple moving average (SMA), monthly productivity index (MPI) and overlay optimum marine conditions for the mackerels were carried out to determine prospects of five recognized fishing grounds at Natuna, Anambas, Tambelan, Lingga dan Bangka. The results showed that Narrow-barred Spanish mackerel in Riau Islands waters, especially Bintan Regency, were caught predominantly with gillnet gear with a size of 10-30 GT. Monthly production of bar mackerel in the 2018-2022 period ranged from 10-105 tons/; from monthly fishing effort of 24-188 trips; with monthly productivity of 0.4-1.1 tons/trip. Oceanographic conditions where mackerels are caught are sea surface temperature 27.50-31.00℃, chlorophyll-a 0.1-0.6mg/m³ and salinity 32.00-33.50‰. While the optimum values for catchable/exportable Narrow-barred Spanish mackerel with are sea surface temperature 29.00-30.00℃, chlorophyll-a L 0.10-0.40mg/m³ and salinity 32.00-33.00‰. August to November the four DPIs of Natuna, Anambas, Tambelan and Bangka are very potential for fishing, in contrast to Lingga which is only potential from February-June. The long fishing season is in Bangka waters (11 months). The spatio-temporal trend shows north-south-north changes in fishing grounds associated with regional climate such as monsoon winds. The spatial- temporal patterns of the prospective fishing grounds for the mackerels can be used by the Agency for Marine and Fisheries Affairs to forecast the fluctuation of landings of the mackerels. The landings are expected to be high from September to December, medium from June to August, and low from January to May. The fisheries during the period of August to November is expected to be busy, i.e., more fishing trips for the mackerels. In the implementation of the Precision Fisheries, the agency can estimate the amount of national income other than tax more precisely. The fish exporters, can predict the fluctuation of landings of the mackerels so they can inform their customers overseas with more precise information on the supply for mackerels.