Djisman Manurung

FISH STOCK ASSESSMENT USING MARINE ACOUSTICS DETECTION AND OCEANOGRAPHICAL CHARACTERISTICS IN JAVA SEA

Study on the movements of pelagic fish as a benchmark of pelagic fish stock assessments were investigated by using marine acoustics detection and oceanographical characteristics. Several surveys during 1992 to1994 using a dual-beam BioSonics 120 kHz echo-sounder installed on R/V Bawal Putih (192 GT) were carried out in the middle part of Java Sea. The objective was to verify the importance of seasonal shifting on fish abundance under strong influence of environmental changes. Data were systematically stored using Ines-Movies acquisition and processing system along isobaths 50m to100m. A depth layer was adjusted under 10m stratifications. Descriptions on environmental frame were done through measurements of temperature and salinity by using Seabirds CTD profiler. The result shows higher saline water above 34 ppm is stronger influenced on the east and central of Java Sea during south-east monsoon (September to October 1992 and 1993). This condition is strongly related to the occurrence of higher fish density. The vertical and horizontal distribution of fish density shows that several group of fish populations seasonally occupied in the area. These observations clarified that coldwater intrusion from the Flores Sea and Makassar Strait play an important role in the west-eastward movements of Java Sea pelagic fish stocks

HALMAHERA EDDY DISPLACEMENT IN RELATION TO PRODUCTIVITY SKIPJACK IN SURROUNDING WATERS

The water between Mindanao and New Guinea is one of areas fisheries potential skipjack (Katsuwanus pelamis) most advanced in the western pacific. The main of fisheries industry this type of dominated by purse-seine by large size (50-100 Gross Tonnage). The role of a Halmahera Eddy is very importance in the dynamics of fisheries in the region, but there is no that explain it yet. Data series arrest skipjack catch per unit of effort (CPUE) of Western Central Pacific Fisheries Commission (WCPFC) for a decade the period July 2002-December 2012 analyzed in order to see the relationship between shifting Halmahera Eddy with the productivity skipjack in the study areas. The results show that the productivity skipjack in the study areas correlates strongly against a meridional shifting of Halmahera Eddy where CPUE showing an increase in skipjack with lag time on two months after Halmahera Eddy center shifted to the north. While to zonal shifting have a correlation in which weak.