Potential of yellowfin tuna catch in East Java-Indian Ocean based on length frequency and age distribution

Tuna's catch in Indonesia is the largest in the world, which contributing approximately 16 percent of the world's tuna supply. Investigation of tuna length frequency distribution that caught in Indian ocean has conducted to know the Indonesian's fisheries potential included yellowfin tuna (YFT). The result study provide useful data for estimating fish growth as a fundamental for YFT stock assessments and managing exploitation. The 203 YFT samples were collected from fish landing area at Sendang Biru Malang, East Java Indonesia during April and May 2017. The research found that YFT in East Java-Indian ocean was dominated with length group of 151-180 cm (53.2 %) and followed by with length group of 121 - 150 cm (33.5%) with estimated age of 4.1 - 6.0 years and 3, 1-4,0 years respectively. There were 17 individual YFT at juvenile size in group length of 31-60 cm was found 8.4%, while the maximum group size (181-120 cm) was reported at level of 4.4%. The variation of YFT length and age indicates the variation of trophic level in East Java -Indian ocean water which very important for sustainable fisheries.