A sediment accretion and carbon accumulation study was carried out in Kamora Estuary, Mimika Regency, Papua Province, Indonesia, to determine the accretion rate and total organic carbon loading in the area as well their correlation with geographical setting and mangrove aerial root type. The...

Wijayanti DP, Indrayanti E, Haryanti D, Wijayanti MK, Elmir ZG, Fachri FR, Bhagooli R, Nozawa Y. 2025. Molecular and risk-based approaches to the status of Goldbanded Jobfish Pristipomoides multidens (Day, 1871) in Kupang, Indonesia. Biodiversitas 26: 928-940. Snappers are economically valuable and important fishing activities in Indonesia. However, the lack of data on the stock status contributes to the uncertainty of the sustainability of the fisheries. We employed the Cytochrome C Oxidase subunit I (COI) mtDNA gene to analyze the genetic diversity of the fish in combination with the Risk-Based Framework (RBF) methods of the Marine Stewardship Council (MSC) to assess the status of the Goldbanded jobfish (Pristipomoides multidens, Day, 1871) fishery at Kupang, East Nusa Tenggara. Results indicated that all specimens collected from Kupang District belong to Pristipomoides multidens (Day, 1871), forming 2 clades. The clades have a low genetic distance, which likely suggests the fish are caught from the same fishing area. The phylogenetic tree reconstruction indicated potential genetic sub-divisions in the snapper population in the Timor Sea. The Risk-Based Framework approach showed the risk potency of the fishing activity has a low effect on the Goldbanded Jobfish, the baitfishes such as mackerel tuna, scads, Indian mackerel and squids, and most of the by-catch fishes. The final MSC score for the Goldbanded Jobfish fishery was 74, below the MSC £80 guide post, suggesting a medium risk potential faced by the fishery. Therefore, catch regulations, such as harvest control rules or open-close fishing should be applied to sustain the fishery.

White shrimp is one of the largest artisanal capture fisheries commodities in Demak. The utilization of these shrimps often overlooks their species category as they are mostly white in appearance. Growing trend of shrimp fishing may affect shrimp management due to population declination to the genetic level since the genetic data are insufficient. Hence, we aim to identify and study the genetic diversity of white shrimp caught in Demak Waters to provide an overview as a reference for fishery improvement project. A random purposive sampling method was used to collect a total of 90 white shrimp specimens from four fishing grounds (Babalan, Gojoyo, Menco, and Seklenting) in the Demak Waters. Specimens were extracted using Chelex 10%, amplified using PCR, and sequenced by the Sanger method based on the mtDNA COI gene. This research revealed the presence of five species of white shrimp: Penaeus merguiensis, Fenneropenaeus penicillatus, Penaeus vannamei, Metapenaeus brevicornis, and Metapenaeus ensis. The genetic diversity studies were continued using the Penaeus merguiensis species only. The results showed 17 haplotypes with a genetic diversity (Hd) of 0.6936 and a nucleotide diversity of 0.00108, which express moderate genetic diversity. Population analysis using Analysis of Molecular Variance (AMOVA) indicated a non-significant difference between the four study populations (panmictic population) with an FST value of 0.00756 (P-value < 0.05). Based on these results, an adequate management of stock is important. For instance, an open-closed season is needed in order to sustain and reduce capture pressure on the white shrimp population in Demak waters.

Understanding the factors influencing the variability in the composition of fish assemblages is essential for bolstering the resilience of coral reef ecosystems, effective coral reef management and maintaining sustainable fisheries. The benthic composition and reef fish assemblages at eight sites at the poorly studied St. Brandon, also known as a bank fisheries area in the Indian Ocean, were assessed to discern distribution patterns, including differences between channel (Passe Grand Capitaine, Passe Ile Longue-Canal Coco and Passe La Cayane) and non-channel (Chaloupe, Anchor Points 1 and 2, Bain des Dames, Pearl Island) sites and fisheries sustainability. The benthic composition exhibited clusters, revealing the distinct separation of Chaloupe which predominantly featured sand (75.26%) interspersed with sporadic coral patches characterized by live and dead corals and rubble. The three channel sites composed a cluster. Coral species across eight families were identified, with significant variability (p < 0.05) observed in their benthic cover, particularly live coral cover (LCC). Fish density and diversity analyses unveiled 58 fish species from 12 families, with no statistically significant disparity in density among sites. Total fish biomass (TFB) and target fish biomass (TB) ranged from 138.02 ± 65.04 to 4110.16 ± 3048.70 kg/ha and from 28.31 ± 24.52 to 3851.27 ± 2753.18 kg/ha, respectively. TFB and TB differed significantly (p < 0.05) among sites irrespective of channel and non-channel sites, with Pearl Island recording the highest biomass. TFB and TB recorded at five out of the eight surveyed sites exceeded the mean biomass benchmark (B₀) for the Western Indian Ocean, set at 1150.00 and 560.00 kg/ha for TFB and TB, respectively. Functional group analysis unveiled six discrete groups influencing TFB, with scrapers being the most dominant. This study presents the first report on fish biomass surveys in St. Brandon, highlighting a case for sustainable fisheries in the waters of the Republic of Mauritius.