Yushinta Fujaya

Blue swimming crab ( Portunus pelagicus ) supports a valuable export fishery in Indonesia, currently estimated at over $400 million per year and employing over 250 thousand workers. High demand has led to the overexploitation of P. pelagicus in recent decades. However, accurately assessing stocks and harvest rates can be difficult. Variation in estimates of harvest sustainability among government, industry, and independent institutions highlights the need for comprehensive assessments. In this study, we examine the crab population in an artisanal nearshore fishery in Parepare Bay, South Sulawesi. We conducted a monthly analysis of the fishery for one year using two methods: (1) surveys of harvested crabs at a landing site and (2) collections of unharvested crabs from four sites in the bay using crab traps. From both methods, the average carapace width for male and female P. pelagicus was approximately 10 cm, and around half of the harvested crabs had not reached maturity. Estimates of spawning potential ratio for P. pelagicus in this fishery were 4%–9%, indicating overexploitation of the stock and impaired recruitment. As an additional aim, we examined the relative abundance of species in the crab community. We found that the bay is dominated by other species of swimming crab, namely Charybdis anisodon and Thalamita crenata . These other species may be predators of P. pelagicus , and high predation rates may further contribute to juvenile mortality in this stock. Achieving a sustainable harvest of P. pelagicus will likely require multiple actions such as enforcement of regulations, restocking of juveniles, and the restoration and protection of nearshore habitats.

This study aimed to analyze the effect of herbal extracts as functional feed additives on the utilization of feed and growth performance of orange mud crabs (Scylla olivacea). The test animals used were 60 crabs for each treatment dose. The crabs are kept individually in a crab box which was placed on a floating bamboo raft. This was to enable floating on the surface of the pond water which had a depth of ±80 cm. The treatments tested were four doses of a combination herbal extract from Morus alba, Curcuma xanthorrhiza, and Boesenbergia rotunda, namely 0, 200, 400, 600 mg kg-1 of feed. Formulated feed with the protein content of 41.93%, fat 7.43%, Nitrogen Free Extract (NFE) 29.33%, and crude fiber 7.82% was given at a dose of 5% body weight every day. Based on one-way ANOVA, the results showed that the dose of herbal extracts influences the feed utilization and growth performance of mud crabs. The dose of herbal extract 600 mg kg-1 of feed provided higher feed utilization and growth performance (LSD Test: P<0.1). Significant differences were found between feed utilization and growth performance of mud crabs after molting and non-molting. In molting mud crabs, treatment with herbal extract 600 mg kg-1 obtained an average weight gain of ±60.73 from the initial weight, compared to control crabs (without herbal extracts) gaining an average weight gain of ±43.73%. However, in non-molting crabs, ±5.44 and ±6.42 weight gain was observed, respectively. Significant differences also occurred between treatments for specific growth rates, feed consumption, feed efficiency, and condition factors. These results provided information that herbal extracts are potentially as feed additives to increase feed utilization and growth performance, as well as stimulate molting in crab cultivation.

Feed is one of the factors that affect the success of hatchery culture of mud crab (Scylla olivacea). The use of artificial feed in the form of microdiet can ensure availability, lower production costs and higher flexibility than natural feed. During this time the artificial feed used is a commercial feed, which is relatively expensive, therefore the need for research to produce artificial feed of good quality, with a cheap price.. The objective of this research is to determine the combination of raw material of artificial feed protein which produce dissolved protein content, protein hydrolysis degree and best protein content of feed. The experimental design used was completely randomized with eight treatments and three replications. The treatments were the use of various combinations of feed protein ingredients : A) 100% Artemia flour, B) 100% fish meal, C) 100% squid meal, D) 50% Artemia and 50% fish meals, E) 50% Artemia and 50% squid meals, F) 50% fish and 50% squid meals, G) 35% fish, 35% squid and 30% Artemia meals, H) commercial feed. The parameters used were dissolved protein content, protein hydrolysis degree and protein feed content. The results showed that the difference of feed protein raw materials had significant effect (p 0,05) than Artemia meal and combination between 50% Artemia and 50% squid meals, but significantly different (P < 0.05) than other treatments. The highest degree of protein hydrolysis in the diet with a protein raw materials was Artemia meal, but not significantly different (P> 0.05) than in commercial feed as well as combination between Artemia and squid meal (P> 0.05), but significantly different (P <0, 05) compared to other treatments. Feed protein content according to the needs of mangrove crab larvae. Fat content with a protein raw materials was 100% artemia meal was higher than the need. Carbohydrate content with a protein raw materials were 100% artemia meal, a combination of 50% artemia meal and 50% squid meal and commercial feed according to the needs of mud crab larvae.