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Pacific bluefin tuna (PBT), Thunnus orientalis, is one of the most important species for aquaculture worldwide. For the conservation of this species and sustainable development of the tuna farming industry, production based on closed‐cycle aquaculture should be promoted. In this study, to develop an efficient method for transporting PBT eggs, we simulated egg transportation to optimize stocking density and shipping duration, which are the two variables critical to the transportation procedure of PBT. Based on the findings of this study, we concluded that PBT eggs should be transported at a density of 1 × 104 eggs/L within 12 h in the field. Furthermore, we showed that collisions between eggs during transportation negatively affected the normal hatching rates of eggs, and polyethylene glycol (PEG) treatment (at 1000 μg/mL for 12 h) could reduce such damage. Our results suggest that PEG treatment is a practical approach that contributes to the stable transportation of PBT eggs, particularly in cases where the effects of physical shock damage is considerably increased.

Highlight Research This is the first study of microplastics in four beach sediments in the east part of Java Island. Bahak and Pesona Beach are connected to Java Sea (north part), while Tambak Rejo and Balekambang Beach are connected to Indian Ocean (south part). A higher microplastics were observed on the beaches of the north part compared to the south part. Local sources and oceanographic parameters of the beaches influence the presence of microplastics in the study areas. Abstract Microplastic pollution in beach sediments has been studied intensively worldwide, but there are limited studies in the beach areas of the eastern Java Island, Indonesia. This study aimed to identify the distribution of microplastic in four beaches in Indonesia: Bahak, Pesona, Tambakrejo, and Balekambang. The first two beaches are located in the north of Java Island and influenced by the east Java Sea, while the last two are located in the south and influenced by the Indian Ocean. Sediment samples were collected along the strandline inside the 1 × 1 m transect quadrate in the top 5 cm using a stainless-steel shovel. Microplastic and granulometry analyses were conducted to obtain microplastic and sediment grain size data, respectively. Physical parameters of the beaches, such as wind, wave, and ocean current, were calculated using Copernicus and NASA (PODAAC), respectively. The total abundance of microplastic ranged from 54.7 ± 48.6 to 103.3 ± 4.7 particles kg-1 with the following descending order: Bahak > Pesona > Tambakrejo > Balekambang. Although there was no statistically significant difference in microplastic concentrations among the beaches, the beaches connected to the Java Sea accumulated more microplastics than the ones connected to the Indian Ocean. Fiber and blue were the dominating type and colors of microplastic. The results confirm that the distribution of microplastic is associated with the morphology of the beaches and the local source.

The morphology of larvae is a key factor influencing their behaviour, performance and ultimately their survival. There is evidence indicating a significant morphological variability among broods, and that this may be related to the size or conditions of the mother. However, this maternal influence is not consistent across decapod crustaceans. Using 35 broods from different mothers of the crab Hemigrapsus takanoi collected in the same locality of inner Tokyo Bay and at the same time, we tested the hypothesis that there is a positive relationship between the size of the mother and the progeny’s morphology. Our results indicate that different patterns in the length of the lateral, rostral and dorsal spines differentiated two distinct morphogroups of larvae. These morphogroups were linked to the size of the mother, showing that larger mothers produced bigger larvae with longer carapace spines. It is possible that larger size and longer spines can influence swimming performance and predator avoidance, respectively. These relationships should be tested in future experimental studies.

In the context of the general overexploitation of South Pacific reef fisheries, there is a global push to precisely define fishery parameters such as fishing effort, annual landings, and exploitation levels. In Bora-Bora, several surveys were performed to define the fishing grounds and the fishing effort of the reef fishery for the first time. Maps of the fishing grounds under different fishing pressures were created for the Bora-Bora reef fishery. The average fishing effort throughout the lagoon was 40 trips week −1 km −2 . Annual landings were estimated following two different methods: school participatory surveys and landing based on the catch per unit effort. These estimations were used to determine that the maximum sustainable yield of the island's fisheries was 6.5 tons km −2 year −1 . the reported annual yield in 2022 was 5.35 tons km −2 year −1 , under the estimated maximum sustainable yield. The level of exploitation of the fisheries was also estimated based on the catch size composition of the ten most fished species. This revealed that fishing is responsible for more than 50% of fish mortality in six of the ten studied species, and that catch length could be increased to optimize both catches and biomass. Overall, the Bora-Bora reef fishery may be experiencing growth overfishing (i.e., the catching of fish that are too small to maximise biological sustainability and economical yield), which can endanger stock recruitment in the future if no actions are taken.

We evaluated the utility of three male‐specific molecular markers, sdY, sdY 227U and OtY2m, in two wild populations of masu salmon (Oncorhynchus masou) in southwestern Hokkaido, Japan. Male‐specific fragments amplified in all phenotypic males across the markers. Phenotypic females were genetically identified as males using sdY (57%) and sdY 227U (4%), but no phenotypic females were identified as males using OtY2m. We conclude that OtY2m was the most reliable sex marker, followed closely by sdY 227U, among those tested in our study populations. Additional research is warranted to test the applicability of these markers in other populations and Oncorhynchus species. We evaluated the utility of three‐male specific molecular markers in two wild populations of masu salmon in southwestern Hokkaido, Japan. We found that some markers are more reliable than others for sex identification in our study populations. Additional research is warranted to test the applicability of our results to other populations and Pacific salmon.

The smallknob flathead, Thysanophrys papillaris Imamura et Knapp, 1999, is redescribed based on six specimens collected from southern Taiwan, which constitutes a northward range extension of the species [previously recorded from the Andaman, Timor, and Arafura seas (eastern Indian Ocean), and Nha Trang, Vietnam (western Pacific Ocean)]. Thysanophrys papillaris is distinguished from all congeneric species in having a combination of 11 second dorsal-fin rays, 12 anal-fin rays, 58–75 scale rows below the lateral line (slanting downward and forward), a longer snout (snout length / orbital diameter ratio 1.1–1.3), 1 or 2 small papillae on the eye, the upper iris lappet with short branches, a single preorbital spine and 3–5 suborbital spines. Previously suggested intraspecific variation in the number of eye papillae is confirmed.

Abstract Coastal areas have become an important part of Indonesia's evolving economy, with a variety of commercial activities taking place. The island of Java has both northern and southern coastal areas, each with its own distinctive characteristics and products. The studies about coastal development through its product value chain are still limited. This study aimed to determine the value chain of fishery products in Java to provide recommendations for enhancing coastal management. For the northern coast, milkfish and ariid catfish from Juwana Coast (Pati Regency, Central Java) were selected, while Whiteleg Shrimp from Mendit Coast and Trisik Coast of Kulon Progo Regency, Yogyakarta were chosen to represent the southern coast. The study involved 48 respondents, including small and medium-sized enterprises (SMEs), farmers, fishermen, wholesalers, middlemen, retailers, restaurants, and consumers. The analysis techniques used in this study included Porter’s value chain, Hayami’s added value, Return/Cost (R/C) Ratio, and marketing margin analysis. The results of the study revealed that the products followed various channels in the value chain, with longer chains leading to higher prices for the end consumers. The findings also indicated that processed and creatively packaged products tend to command higher prices and generate greater profits. Coastal management should not only focus on upstream activities but also consider downstream processes to increase the value of coastal products. Efforts to enhance coastal management should consider key actors and government interventions through developing the coastal local products. Highlight Research The coastal area of Java Island makes a significant contribution to the local economy. The supply chain of Whiteleg Shrimp, Ariid Catfish, and Milkfish involves various actors who play important roles in maintaining the distribution of coastal products. Value chain analysis reveals opportunities to increase and improve the quality of products to enhance their worth. It is necessary to enhance coastal management by involving local institutions, the government, and the private sector.

The coypu ( Myocastor coypus ) is a semi-aquatic herbivorous rodent that has been suspected to prey on freshwater unionid mussels in Japan. Fecal DNA metabarcoding that targeted bivalves and terrestrial plants was performed to examine the diet of exotic coypu in the Kiso River, central Japan. Thirty-two fecal samples from four floodplain waterbodies were collected seasonally. In one of the waterbodies, live and dead mussels were investigated to examine the possible effects of coypu predation on mussel population structures. Common coypu predation on unionid mussels was confirmed in two waterbodies. Midden surveys showed that medium- to large-sized mussels tended to be consumed by coypu; possibly resulting in population structures with few large-sized individuals. Seasonal diet selection of terrestrial plants was also detected: two perennial plants were consumed throughout the year, whereas some perennial plants were consumed seasonally. The number of terrestrial plant species/taxa as primary food was higher in summer than in winter, which was attributed to the high consumption of annual plants in the summer. Future studies need to examine the exhaustive diet of coypu including other animals and plants, as well as its effects on freshwater ecosystems in invaded regions. Le ragondin ( Myocastor coypus ) est un rongeur herbivore semi-aquatique que l'on soupçonne être la proie des moules unionidées d'eau douce au Japon. Un métabarcodage de l'ADN fécal ciblant les bivalves et les plantes terrestres a été effectué pour examiner le régime alimentaire du ragondin exotique de la rivière Kiso, au centre du Japon. Trente-deux échantillons de matières fécales provenant de quatre plans d'eau de plaine d'inondation ont été prélevés de façon saisonnière. Dans l'un de ces plans d'eau, des moules vivantes et mortes ont été étudiées afin d'examiner les effets possibles de la prédation du ragondin sur les structures des populations de moules. La prédation courante du ragondin sur les moules unionidées a été confirmée dans deux plans d'eau. Les études des buttes dépotoir ont montré que les moules de taille moyenne à grande ont tendance à être consommées par le ragondin, ce qui peut entraîner des structures de population comportant peu d'individus de grande taille. La sélection saisonnière du régime alimentaire des plantes terrestres a également été détectée : deux plantes pérennes ont été consommées tout au long de l'année, tandis que certaines plantes pérennes ont été consommées de façon saisonnière. Le nombre d'espèces/taxa végétales terrestres comme aliment principal était plus élevé en été qu'en hiver, ce qui a été attribué à la forte consommation de plantes annuelles en été. Les études futures doivent examiner le régime alimentaire exhaustif du ragondin, y compris d'autres animaux et plantes, ainsi que ses effets sur les écosystèmes d'eau douce dans les régions envahies.

A monitoring programme was established to collect plankton samples and information of environmental variables over the shelf off the island of Gran Canaria during 2005 and 2006. It produced a detailed snapshot of the composition and seasonal assemblages of the decapod larvae community in this locality, in the subtropical waters of the Canary Islands (NE Atlantic), where information about crustacean phenology has been poorly studied. The larval community was mainly composed of benthic taxa, but the contribution of pelagic taxa was also significant. Infraorders Anomura (33.4%) and Caridea (32.8%) accounted for more than half the total collected larvae. High diversity, relatively low larval abundance throughout the year and weak seasonality characterized the annual cycle. However, in relation to the temporal dynamics of temperature, two distinct larval assemblages (cold and warm) were identified that correspond to periods of mixing and stratification of the water column. The results also indicate that larval release times and durations in the subtropical waters are earlier and longer than at other higher latitudes in the NE Atlantic. We detected the presence of larvae of six species that have not yet been reported from the Canary Islands (Pandalina brevirostris, Processa edulis, Necallianasa truncata, Parapenaeus longirostris, Crangon crangon, Nematopagurus longicornis). Finally, this study provides a baseline for future comparisons with respect to fishery pressure and climate variability in this subtropical region.