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Bonito plays an important role as the main ingredient for marinated products and provides a livelihood for coastal communities. Given the emergence of Indonesia's over-exploited small-scale marine fisheries resources, this study aims to characterize and evaluate fishery’s sustainability based on bioeconomic analyses. Time series catch and effort data were collected from 2005 to 2019 provided by Archipelagic Fishing Port of Prigi. Five surplus production models were also employed to generate catch-and-effort-based biological parameters, namely intrinsic growth rate (r), catchability (q), and carrying capacity (K). By adding economy parameters such as cost and price, the sustainability of catch and effort was also estimated at three management conditions. The catch abundance was peaked in April and September, characterized by the lack of rain. The CPUE was varied inter-annually. However, it declined during the last decade, indicating that the stock size was decreased. Although the average catches from 2015-2019 (9,984 tons) are lower than CMSY (11,695 tons). However, the effort in 2019 (15,239 trips) has exceeded EMEY (14,237 trips). Hence, reducing fishing efforts or maintaining it at E2018 level was suggested as a precaution to keep the fishery’s sustainability and simultaneously generate optimum profit.

The stock status of yellowfin tuna (Thunnus albacares) (YFT) in the Indian Ocean is currently concluded overfished and is subject to overfishing. The information about the YFT population structure is fundamental for effective fisheries management and conservation. The otolith shape as a tool for estimating population structure is the cheapest technique compared to other methods, such as genetic, parasite, and otolith chemistry, especially for analyzing the large samples. This study investigates the use of otolith shapes to determine the yellowfin stock from two different locations. Data collection was carried out at two locations, namely Kedonganan and Benoa, throughout 2018. Total samples collected from the two study sites were 314 otoliths, but only 147 whole otoliths could be analyzed. Image analysis was performed using ANOVA-like permutation (n=1000 to determine whether the individual can be reclassified to their sample origin. The subsequent analysis is the variations in the shape of the otolith with multivariate statistical methods using cluster analysis with Canonical Analysis of Principal Coordinates. The result shows that the YFT otolith Benoa is significantly different from the YFT otolith Kedonganan with the P-value = 0.0015.

The stock of yellowfin tuna (Thunnus albacares) has been in a declining trend in the last five years. Although the noticeable decline mainly occurred in the western part of the Indian Ocean, uncertainty lingers on how this phenomenon will affect the opposite leg. The study aimed to investigate the dynamics of stock through monitoring several indicators by utilizing logbooks, scientific port sampling, and observer data available. The result showed that both relative abundance and estimated catch trend are declining in recent years, a sign that the negative global inclination also influences Indonesian tuna longline fisheries. Further studies are needed to understand whether this phenomenon also impacts other gears. Hence, mitigation on conserving the resource by reducing the catch and strengthening the data collection should be the priority to maintain the livelihood and welfare of many coastal communities.

Knowledge of reproduction biology provides valuable information to better understanding population dynamics, including a population's resilience to fishing. The yellowfin tuna reproductive biology in the eastern Indian Ocean was studied by analyzing some essential characteristics: size at maturity, the spawning season, frequency of spawning, egg diameter, and batch fecundity. From 2018 to 2020, 206 female yellowfin tuna were sampled (23-170 cmFL). They were using histological and morphological analysis, resulting in the size at maturity (Lm50) of yellowfin tuna being 92.73 cmFL. The spawning season of yellowfin tuna occurred between September and May, spawning every 1.55 days within the spawning period. The oocytes size ranged between 27.1 – 570.5 μm, and the mean size of oocytes (mean ± standard deviation) was 189.5±129.4 μm. The mean batch fecundity was 3.1±1.7 million oocytes, and the mean relative batch was 82.4±38.4 oocytes gram-1 of GGT weight. The uncertainties in current yellowfin stock assessment models can be reduced by providing complete information on the reproductive traits in the region to achieve a sustainable fishery.