Dispersal of yellowtail kingfish (Seriola lalandi) from a coastal embayment following a recreational fisheries enhancement stocking program: attempts to integrate aquaculture and habitat-based initiatives

Fisheries enhancement initiatives including marine stocking and artificial reef deployments are becoming increasingly common in many parts of the world. Combining the two by releasing hatchery reared fish onto artificial reefs is used in sea-ranching operations but is an approach rarely adopted for recreational fisheries. Yellowtail kingfish (Seriola lalandi) form a valuable recreational fishery in Australia and in 2018 a pilot stocking program was initiated to enhance this fishery. Fish were released onto estuarine artificial reefs in Botany Bay to evaluate if estuarine artificial reefs are suitable release habitat for juvenile yellowtail kingfish and to monitor their dispersal patterns using acoustic telemetry and a tag-recapture program. Both approaches showed similar patterns, indicating juvenile yellowtail kingfish rapidly dispersed from the release location and can travel at least 60 km during their first weeks in the wild. Twenty percent of the acoustically tagged fish entered nearby estuaries to the north and south and tagged fish were also recaptured in these estuaries, indicating that the estuaries provide habitat for juveniles. There was little interaction between stocked fish and two large coastal artificial reefs positioned near Botany Bay. Stocked yellowtail kingfish will likely disperse rapidly from release locations which is consistent with their pelagic life history. While this may present challenges to fisheries managers, increasing release numbers to maintain stocking densities over a broader area may provide a solution. Future releases of fish on coastal natural and artificial reefs are an important next step in refining stocking practices for this species and will help further identify key juvenile habitats.

Some scientific issues related to biological resource use and management toward sustainable development of marine economy in the costal provinces in South Central Vietnam

Based on referring recent target scientific issues related to sustainable development in the world and considering practices of economic development in the provinces of South Central Vietnam, some issues were selected for analyses in terms of concepts, needs and orientations applicable to the region. They include, inter alia: Economic valuation of marine ecosystems; Important levels of habitats in coastal ecosystems; Rehabilitation and restoration of degraded resources; Natural hazards - prevention and resilience; Marine protected areas and fisheries enhancement; Deoxygenation in marine environment and economic losses in fisheries.

Short Communication: Application of artificial reefs for fisheries enhancement in Probolinggo, Indonesia

Isroni W, Samara SH, Santanumurti MB. 2019. Short Communication: Application of artificial reefs for fisheries enhancement in Probolinggo, Indonesia. Biodiversitas 20: 2273-2278. Overfishing is one of the biggest challenges in the fisheries sector in Probolinggo, Indonesia. The fish apartment (artificial reefs) was one of the solutions to increase the fish resource since it serves as the habitat for fish to live, spawn, and search for food. In this study, the fish apartment was installed in Probolinggo (Karang Katon and Dringu Beach) from 2017 to 2018. This study showed that five fish species (Caesio cuning, Acanthurus achilles, Acanthurus albipectoralis, Sphyraena jello, and Apagon novemfasciatus) were found in Karang Katon while four species (Chaetodon octofasciatus, Chromobotia macracanthus, Nemipterus japonicas, and Lates calcarifer) lived in Dringu Beach. From a total of 333 fishes, A. achilles was the species with the highest composition level of 51.65% (172) in Karang Katon station. In Dringu Beach station, C. octofasciatus had the highest fish species composition level of 46% (183) from a total of 402 fishes. The diversity index and dominance index in Karang Katon station were low at-1.280 and 0.343, respectively. The diversity index and dominance index in Dringu Beach station were also low at -1.115 and 0.3503. A. achilles had the highest density of 34.4 ind/m3 in Karang Katon station while C. octofasciatus had the highest species density of 36.6 ind/m3 in Dringu Beach Station. From this study, it could be concluded that artificial reefs application enhanced the fisheries in Probolinggo, Indonesia, and help its sustainability.

Density-dependent growth in ‘catch-and-wait’ fisheries has implications for fisheries management and Marine Protected Areas

Stock enhancement activities provide an opportunity to examine density-dependent suppression of population biomass which is a fundamental issue for resource management and design of no-take-zones. We document ‘catch-and-wait’ fisheries enhancement where all but the largest lobsters are thrown back, recapturing them later after they have grown to a larger size. The residency, rate of return, and potential negative density-dependent effects of this activity are described using a combination of tagging and v-notching and by relating spatial growth patterns to population density defined with Catch Per Unit Effort. The results successfully demonstrated the concept of catch-and-wait practices. However, a density-dependent suppression of growth (in body size) was observed in male lobsters. This demonstrates a mechanism to explain differences in lobster sizes previously observed across EU fishing grounds with different stock densities. This negative effect of density could also affect individual biomass production in marine reserve or no-take zones.

KEBIJAKAN PEMACUAN SUMBERDAYA IKAN DI PERAIRAN UMUM DARATAN INDONESIA: TEKNOLOGI ALTERNATIF UNTUK MENINGKATKAN PRODUKSI IKAN DAN PENDAPATAN NELAYAN

Pemacuan sumberdaya ikan adalah suatu teknologi untuk meningkatkanhasil tangkapan ikan dan sekaligus pendapatan nelayan. Potensi produksi ikan perairan umum daratan Indonesia (luasnya 13,85 juta ha) ditaksir 3.034.934 ton/th, sedangkan produksi ikan yang telah dicapai 325.000 ton/th. Berdasarkan keberhasilan penerapan pemacuan sumber daya ikan di beberapa badan air, produksi ikan dapat ditingkatkan menjadi 1.452.947 ton/th. Ke depan, penerapan kebijakan pemacuan sumber daya ikan yang selama ini kurang didasarkan hasil kajian yang memadai perlu diperbaiki. Untuk setiap badan air perlu ditetapkan protokol pemacuan sumber daya ikan. Protokol tersebut meliputi identifikasi sumber daya perairan, menentukan tujuan penebaran, menentukan jenis, jumlah dan ukuran ikan, serta biaya yang diperlukan, mengembangkan strategi penebaran, monitoring dan evaluasi, serta pembentukan kelembagaan pengelolaan. Pedoman pemacuan sumber daya ikan di Indonesia perlu segera ditetapkan yang mengacu pada tata laksana perikanan yang bertanggungjawab.Fisheries enhancement is a technique to increase fish yield and fishers’income. Fish potential yield of inland open waters (13.85 million ha in area) was estimated at 3,034,934 ton/yr, while an average of the actual fish production was 325,000 ton/yr. Based on the success story of fisheries enhancement techniques applied in some water bodies, the fish yield total can be increased to be 1,452,947 ton/yr. In the future, application of policy on fisheries enhancement should be improved. Protocol on fisheries enhancement should be designed for every waterbody. The protocol should consit of identification of fisheries resources,establishment of the objective, determine a suitable fish species, optimum number and size of fish released, estimation of total cost, development of stocking strategy, monitoring and evaluation, and establishment of fisheries management unit. A guideline of fisheries enhancement in Indonesian inland open waters need to be constructed referring to code of conduct for responsible fisheries.