MIHROBI KHALWATU RIHMI
Program of Fisheries Resource Utilization, Faculty of Fisheries and Marine Science, Universitas Brawijaya. Jl. Veteran, Malang 65145, East Java, Indonesia

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Biological parameters and spawning potential ratio of Longtail Tuna Thunnus tonggol landed in Kranji fishing port, Lamongan District, Indonesia LEDHYANE IKA HARLYAN; MUHAMMAD ARIF RAHMAN; MIHROBI KHALWATU RIHMI; SYA’DIYA FAHMA ARMI ABDILLAH
Biodiversitas Journal of Biological Diversity Vol. 24 No. 12 (2023)
Publisher : Society for Indonesian Biodiversity

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.13057/biodiv/d241214

Abstract

Abstract. Harlyan LI, Rahman MA, Rihmi MK, Abdillah SFA. 2023. Biological parameters and spawning potential ratio of Longtail Tuna Thunnus tonggol landed in Kranji fishing port, Lamongan District, Indonesia. Biodiversitas 24: 6527-6535. Longtail Tuna (Thunnus tonggol), one of the small-pelagic tropical fisheries in the Fisheries Management Area (FMA-712), is important in supporting global food security. Therefore, to ensure its sustainability, this fishery is applying for fishery certification to be an ecolabel fishery by the Marine Stewardship Council (MSC). However, limited information about Longtail Tuna's biological parameters and stock status in this management area will lead to failure in certification completion. This study aims to provide biological parameters and stock status of Longtail Tuna landed in the Kranji fishing port, Lamongan, Indonesia. Length, weight, and gonad weight of female Longtail Tuna individuals which landed in the Kranji fishing port were conducted from January to April 2023. Several analyses were carried out to figure out the biological parameters of Longtail Tuna, such as length-weight relationship, length at first maturity ( ) and length at first capture ( ) estimation. Length-Based Spawning Potential Ratio (LB-SPR) analysis was conducted to estimate fish exploitation. Results showed that the Longtail Tuna landing in the Kranji fishing port exhibited a negative allometric growth pattern with the length-weight relationship model W = 0.0433 FL2.7608. A comparison between  (43.9+0.11cm) and  (43.6+0.04cm) indicated that most female Longtail Tuna landed in the Kranji fishing port are mature (60% of the total samples). The LB-SPR analysis showed moderate exploitation status (SPR = 34%). Fishing activities are still manageable in this situation by focusing on stock sustainability. An overlapping fishing ground occurs in the Kranji water, showing the domination of two species landed in the Kranji fishing port, Longtail Tuna and Eastern Little Tuna (Euthynnus affinis). Therefore, Longtail Tuna fishery management might also consider fishery management of Eastern Little Tuna or other species with overlapped habitats.
Species identification and population dynamics of cuttlefish Sepia spp. (Mollusca: Cephalopoda) landed at Brondong Fishing Port, Lamongan, East Java, Indonesia DADUK SETYOHADI; MUHAMMAD ARIF RAHMAN; LEDHYANE IKA HARLYAN; MIHROBI KHALWATU RIHMI
Biodiversitas Journal of Biological Diversity Vol. 25 No. 4 (2024)
Publisher : Society for Indonesian Biodiversity

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.13057/biodiv/d250403

Abstract

Abstract. Setyohadi D, Rahman MA, Harlyan LI, Rihmi MK. 2024. Species identification and population dynamics of cuttlefish Sepia spp. (Mollusca: Cephalopoda) landed at Brondong Fishing Port, Lamongan, East Java, Indonesia. Biodiversitas 25: 1359-1367. Cuttlefish (Sepia spp.) is one of Indonesia’s fisheries resources with high economic value. It is often caught in the northern Java waters, including Lamongan. As it is high value, cuttlefish resources should be managed to ensure sustainability. However, information on its biology and population dynamics is limited as the basis of fisheries management. This research aimed to identify species of cuttlefish and to estimate its biological aspects and population dynamics. Samples were randomly collected at Brondong Fishing Port from July to September 2022. The result indicated that there were two species of cuttlefish, Sepia aculeata (needle cuttlefish) and Sepia pharaonis (pharaoh cuttlefish), with a proportion of 57.1 and 42.9%, respectively. In addition, S. pharaonis was bigger and heavier than S. aculeata. The mean mantle length = 10.5 cm and weight = 166.6 g for S. aculeata, while S. pharaonis has mean mantle length = 11.4 cm and weight = 208.1 g, and both species have negative allometric growth patterns. Moreover, the asymptotic mantle length (L?) = 24.6 cm and 22.7 cm, growth rate (K) = 0.68 year-1 and 0.78 year-1, total mortality rate (Z) = 1.96 year-1 and 4.61 year-1, natural mortality rate (M) = 0.97 year-1 and 1.64 year-1, fishing mortality (F) = 0.99 year-1 and 2.97 year-1, and exploitation rate (E) = 0.51 year-1 and 0.65 year-1 for S. aculeta and S. pharaonis respectively. This finding might contribute to managing cuttlefish fishery in the north Java waters, especially in East Java.