The existence of mackerel scad in Ambon waters, Moluccas Indonesia has decreased from year to year mainly due to the over exploitation. This research aimed to study the biological aspects, in particular were sex ratio, age group and length at first maturity of mackerel scad (Decapterus macarellus) from this area. Sampling was done on September 2016 to July 2017 at the southern waters of Ambon Island. Samples collected were dissected to determine their sex and their gonad maturity level then measured. Bhattacharya method was used to determine age group while Spearman- Kaber method was used to identify length at the first maturity of this species. It was found that mackerel scad in the southern waters of Ambon Island had an equal number of male and female that consists of four age groups with length at first maturity for male and female were 24.9 cm and 24.8 cm, respectively.

In Maluku, Indonesia, trap fishing is one of the traditional fisheries that plays an important role in supplying reef fish to sea food restaurants and to the trade of live fish. To support the implementation of ecosystem-based fishery management, it is important to analyse the catch of trap through a multi-species approach rather than a single-species (selectivity) approach. In this study, multi-species catch analyses estimated species diversity, trophic levels and spatial distribution based on catch data, and sustainability of catch based on biological and ecological information. Traps were fished from February 2018 to January 2019 in waters 5 to 40m deep in Ambon Bay, Waai Bay and at Babar Island. The most abundant fishes caught were the family Mullidae, Parupeneus barberinus (n = 102) and P. indicus (n = 126). Spatial distribution of species analysed with Multivariate Principle Component Analysis showed each trap has significant co-varying species. The mean trophic level of the traps was 3.37 (SE: 0.175), indicating that the trap catches were dominated by low to moderate levels of carnivorous secondary consumers. From 42 species captured by traps, the least likely to be sustainable was Heniochus cuminatus and the most likely to be sustainable were, Selar boops. It is proposed that traditional trapping is a suitable practice in coral reef areas, with low impacts on the community of reef fish that eventually supporting balance fishery.

Yellowfin tuna (Thunnus albacares) is one of large pelagic potential and economical species from the family of Scombridae. Production of yellowfin tuna from several potential fisheries areas (WPP) in Maluku was reported in the condition of overfishing. Meanwhile, tuna fisheries have been the potential resource for export demand. It is therefore, the status of yellowfin tuna fisheries should be monitored regularly following the regulation of PERMEN KP no 4 year 2017. The aims of this study were to measure the size of maturity of yellowfin tuna during October to December 2018 and utilize the empirical relationship to estimate optimum length and maximum length reached during this period. Observation on yellowfin tuna was conducted by joining local fishers from Kawa village, West Seram Regency. Handlines were occupied to catch yellowfin tuna around Banda Sea. From the catch sizes ranged from was 34cm to 168cm, the length maturity (Lm) of yellowfin tuna is 107.2cm of total length for female and 112.9cm for male. From the empirical relationship, the optimum length (Lopt) of yellowfin tuna during October-December 2018 was 120.5cm and maximum length (Lmax) was 181.4cm. This study showed that 90% of yellowfin catch was immature which indicated a recruitment overfishing. Only 2.4% of mega-spawners were caught during this study and indicated growth overfishing. Indication of an overfishing of the yellowfin tuna fishery contradicted to larger size of first maturity found. This contrary is discussed and balance fishing strategy is proposed as the idea to maintain the population of yellowfin tuna.

Gillnets are widely used by small-scale fishermen to catch giant travelly Caranx ignobilis in coastal waters, the dominant fish caught are small in size not according to market size. The parameters of gillnet such as mesh size and hanging ratio can optimize the target size. The purpose of this study was to analyze the effect of mesh size and hanging ratio of gillnets on the size of the local marketable size for C ignobilis. The fishing experiment was carried out in floating net cages at the Ambon Fisheries Training and Extension Center (BPPP) from June to August 2022. A Simple randomized experimental designed with a factorial pattern was used as the experimental model. The different mesh size were used as treatments, and they are 2.5, 3.0 and 3.5 inches (3 factors) and the hanging ratio consisted of 70%, 50% and 30% (3 factors). The population of C ignobilis that was used in this study with the middle of the class ranged from 24.5 to 29.5 cm total length. There is an effect of mesh size factor on the size of the target market for C ignobilis, where the mesh size of 3.0 inches is more effective than the others. In addition, the hanging ratio value affects the catch size of the local target market, where the hanging ratio value of 30% is more effective than the hanging ratio value of 70%. .