Population Dynamics of Bullet Tuna (Auxis rochei Risso 1881) from the Indian Ocean, West Nusa Tenggara, Indonesia

Abstract

Highlight Research:The bullet tuna (Auxis rochei) was identified and analysed.The length at first maturity (Lm) of bullet tuna (Auxis rochei) was analyzedThe eligibility status of bullet tuna (Auxis rochei) has been analyzed and estimatedThe LWR curve can be used to estimate age groups of fish compared to the sigmoid curveThe CF cannot be automatically used to estimate fish worth selling AbstractThe bullet tuna (Auxis rochei), BLT or tongkol lisong (Indonesian) is a species of neritic tuna which is one of the target fish for small scale fishers. The problem of bullet tuna fisheries was that it has reached overexploitation and the immature bullet tuna are still caught. This study aimed to assess the population dynamics of the BLT and its size composition caught by small scale fishers in the Indian Ocean, West Nusa Tenggara area was carried out in Bangko-Bangko (West Lombok), Cemplung Beach (South Sumbawa) and Tanjung Luar Fishing Port (East Lombok) between July 2019 and June 2020. The data was derived from the measurement and weighing results of 1,217 BLT collected from the respective collector traders at each sampling location. The growth pattern of BLT was isometric () which meant the ideal body shape (mesomorph) and length at first maturity (FLm) was 31.11 cm. The length-weight relationship curve showed that BLT was in an immature age group (adolescent fish). Meanwhile, the composition of BLT is worth selling (Condition Factor > 1.00), fit for catch (FLc / FLm > 1.00) and worthy of maturity (FLc > FLm), respectively 99.92%, 0.82% and 0.00%. The BLT fish composition indicates that the stocks of resources and populations do not support current sustainable fisheries management.

The effect of continuous lighting on the rearing of yellowfin tuna (Thunnus albacares) larvae

“…To determine the average seed produced and the best growth rate at the end of the study, data analysis with a t-test was analyzed. The research on the rearing of yellowfin tuna larvae does not require special permits because the larvae used come from hatching eggs from cultivated parents; and yellowfin tuna is not included in protected fish [2].…”

“…Tuna (Thunnus albacares) has an important economic value in the world market and contributes greatly to the export of fishery commodities in Indonesia [1]. The total annual catch of yellowfin tuna in the Indian Ocean from 1980 increased significantly between 2014 and 2018 with an average annual catch of around 404,655 tons [2].…”

Biological aspects of bullet tuna (Auxis rochei Risso, 1810) landed in Towo’e Market Tahuna Indonesia

“…The bullet tuna is a fish resource that is epipelagic, neritic, and oceanic in warm waters such as Indonesia [8]. In Indonesia, the bullet tuna is distributed in the Indian Ocean waters west of Sumatra [9], Makassar Strait [10][11][12], Indian Ocean south of Java, Bali, and Nusa Tenggara [13][14][15][16], Bone Bay [17] and Banda Sea [18]. The bullet tuna is usually caught with fishing gear such as gillnet, hand line, troll line, lift net, purse seine and seine net [9], [19].…”