Monitoring the Performance of Set Longlines Fishing Vessels at Fisheries Management Area 718 Indonesia

Catches reports by set longlines fishing vessels in the 718-fisheries management area (FMA) have been entered into the logbook reporting system since 2012. These vessels targeted reef and demersal fish. Set longlines is considered to be very efficient and productive for catching reef fish. This study aims to see the performance of set longlines vessels. The indicators used are CPUE and fuel efficiency. The results of the study show that the performance of set longlines vessels in the area is getting better and more efficient. Keywords: set longlines; reef fish; CPUE; fuel; efficient Abstrak Laporan hasil tangkapan oleh kapal penangkap rawai dasar di pengelolaan perikanan (WPP) 718 telah dimasukkan ke dalam sistem pelaporan logbook sejak 2012. Kapal-kapal rawai tesebut menargetkan ikan karang dan ikan demersal. Rawai dasar dianggap sebagai alat tangkap yang sangat efisien dan produktif untuk menangkap ikan karang. Penelitian ini bertujuan untuk melihat kinerja kapal rawai dasar. Indikator yang digunakan adalah CPUE dan efisiensi bahan bakar. Hasil penelitian menunjukkan bahwa kinerja kapal longline set di daerah tersebut semakin baik dan efisien. Kata kunci: rawai dasar; ikan karang; CPUE; bahan bakar; efisien

Underwater Photogrammetry Captures the Initial Recovery of a Coral Reef at Lalo Atoll

Recovery of coral reefs after physical damage sustained from storm events can be affected by various factors. Here, we examined the initial recovery of a coral reef at the southern end of uninhabited Lalo Atoll of Papahānaumokuākea Marine National Monument after its complete destruction by Hurricane Walaka in 2018. While the site was still mostly (98%) covered by a mixture of rubble and sand, surveys utilizing underwater photogrammetry allowed for detailed quantitative assessments of benthic cover and confirmed colonization of coral (Pocillopora meandrina and Porites lobata), macroalgae and sponges. The proportion of sand in the rubble–sand mixture also decreased from the level observed in 2019. Visual fish surveys confirmed the presence of 35 reef fish species, a large increase from no reef fish in 2019, despite the low biotic benthic cover. Overall, the colonization of benthic organisms and the return of reef fish, which is potentially supported by the benthos and cryptofauna in the rubble bed, offer positive signs of reef recovery. The photogrammetric surveys in the present study captured the subtle changes in the benthic cover and provided us with a procedure to continue monitoring the succession of the site. Continuous monitoring of the site should reveal whether the reef returns to the original state of Acropora coral dominance or progresses towards a coral assemblage with a different composition.

Predicting Future Shifts in the Distribution of Tropicalization Indicator Fish that Affect Coastal Ecosystem Services of Japan

Tropicalization characterized by an increase in marine species originating from the tropical waters affects human society in various ways. An increase in toxic harmful species negatively affects fisheries and leisure use, and an increase in herbivorous fish affects fisheries and carbon sink capacity by decreasing seagrass/seaweed beds. On the other hand, an increase in tropical reef fish attracts more tourism. This study aimed to predict future shifts in the distribution of functional groups of tropicalization indicator fish that can affect marine ecosystem services in temperate coastal waters of Japan. We estimated the distribution of harmful fish Aluterus scriptus and Scarus ovifrons, herbivorous fish Kyphosus bigibbus and Siganus fuscescens, and tropical reef fish Amphiprion frenatus and Chaetodon auriga by collecting their distribution data from open databases. Distributions in 2000–2018 and the future (2046–2055 and 2091–2100) under different climate change scenarios (the representative concentration pathways; RCPs) were estimated using a species distribution model. We used environmental variables such as minimum sea surface temperature (SST), depth, slope, coral reef area, and seagrass/seaweed bed area as predictors and carried out future predictions using the future ocean regional projection (FORP) dataset. The minimum SST was the factor most responsible for the estimated distribution patterns for all species. The depth, slope, and seagrass/seaweed bed were also important for some species. The estimated probability of occurrence was high along the Pacific coast, which was affected by the warm Kuroshio Current and Tsushima Current along the coast of the Sea of Japan. Projected shifts in distributions based on different RCP scenarios showed that these indicator species would significantly increase their distribution in the middle to northern parts of Japan (32–37°N). By the 2090s, their habitat range was estimated to increase to 1.2–1.9 times that of 2000-2018 with severe warming (RCP8.5). However, the target species habitat range would not change significantly with stringent mitigation (RCP2.6). Our results suggest that ambitious commitment to reducing CO2 and other greenhouse gas emissions, such as following the Paris Agreement, will alleviate future tropicalization. Moreover, the fine resolution results can also be directly used for planning climate adaptation programs for local decision makers.

Quantifying Mesophotic Fish Assemblages of Hawai‘i’s Au‘au Channel: Associations With Benthic Habitats and Depth

Mesophotic reefs (30–150 m) occur in the tropics and subtropics at depths beyond most scientific diving, thereby making conventional surveys challenging. Towed cameras, submersibles, and mixed-gas divers were used to survey the mesophotic reef fish assemblages and benthic substrates of the Au‘au Channel, between the Hawaiian Islands of Maui and Lāna‘i. Non-parametric multivariate analysis: Non-metric Multidimensional Scaling (NMDS), Hierarchical Cluster Analysis (HCA), Multi-Response Permutation Procedure (MRPP), and Indicator Species Analysis (ISA) were used to determine the association of mesophotic reef fish species with benthic substrates and depth. Between 53 and 115-m depths, 82 species and 10 genera of fish were observed together with 10 types of benthic substrate. Eight species of fish (Apolemichthys arcuatus, Centropyge potteri, Chaetodon kleinii, Chromis leucura, Chromis verater, Forcipiger sp., Naso hexacanthus, and Parupeneus multifasciatus) were positively associated with increasing depth, Leptoseris sp. coral cover, and hard-bottom cover, and one species (Oxycheilinus bimaculatus) of fish was positively associated with increasing Halimeda sp. algae cover. Fish assemblages associated with rubble were not significantly different from those associated with sand, Montipora coral beds and Leptoseris coral beds, but were distinct from fish assemblages associated with hard bottom. The patterns in the data suggested two depth assemblages, one “upper mesophotic” between 53 and 95 m and the other deeper, possibly part of a “lower mesophotic” assemblage between 96 and 115 m at the edge of the rariphotic and bottomfish complex.

Environmental DNA Biomonitoring Reveals Seasonal Patterns in Coral Reef Fish Community Structure

Coral reef fish populations are declining due to multiple factors including habitat destruction, overfishing, and climate change. While these can include seasonal impact, seasonal changes can also be a confounding factor, so that seasonal monitoring is essential for detecting true temporal changes in fish community abundance and composition. However, seasonal monitoring is rarely implemented. The aim of this study was to detect the seasonal patterns of coral reef fish community structure around Tidung Kecil Island, Indonesia, using eDNA metabarcoding (eDNA) and underwater visual census (UVC). The UVC identified 32 species belonging to 10 families in the rainy season and 29 species belonging to 7 families in the dry seasons. The eDNA metabarcoding identified 209 species belonging to 56 families and 27 species belonging to 17 families in the rainy and dry seasons, respectively. Based on eDNA metabarcoding data, coral reef fish abundance and community composition differed significantly between seasons (Mann Whitney, p<0.01), while the UVC method did not detect these seasonal differences (Mann Whitney, p>0.05). UVC and eDNA data both showed a predominance of omnivorous fishes in the rainy season and carnivorous fishes in the dry season. Ecological indices did not differ significantly between seasons for either method, although the species making the highest contributions to the similarity (SIMPER) analysis differed between methods. Overall, this study confirms the premise that eDNA metabarcoding can be an effective tool for monitoring seasonal variation in coral reef fish communities.

Reproductive timing and investment decisions of a protogynous hermaphroditic coral reef fish species

<p>Life-history theory suggests that an organism must balance its available energy between two competing physiological processes to maximize fitness: reproduction and somatic growth. Energetic trade-offs are a fundamental concept of life history theory and form the basis of intra- and inter-specific variation in life-history strategies. In fishes, reproduction-growth trade-offs are an essential component of life-history optimization. This is particularly true for species with protogynous sex- change (the most common reproductive mode among coral reef fish species), where reproductive success rapidly and disproportionally increases with body size/ corresponding social status. In such systems, lifetime fitness is inherently linked to patterns of growth and energy allocation strategies determined by an individual’s size-specific rank within the dominance hierarchy. However, energy allocation strategies in a protogynous species may not only be a function of body size. Coral reef fish species are exposed to extremely variable environmental conditions and this can favour the evolution of strategies that utilize good times and avoid disadvantageous times for reproduction. Consequently, size- specific parental investment decisions may vary greatly in time and space according to environmental cues. My thesis focuses on the protogynous reef fish, Thalassoma hardwicke (the sixbar wrasse), which is extremely abundant on shallow coral reefs throughout the Indo-Pacific region. Specifically, I evaluate patterns of spawning and reproductive investment as a function of body size, social status, lunar phase and other environmental parameters. I address the question of whether females/males of differing size make different fitness-related decisions when away from spawning sites, and I evaluate context-dependency in these decisions. Finally, I will attempt to reconstruct the developmental histories (e.g., larval growth rates) of individuals from otoliths to evaluate potential relationships between developmental histories and fitness attributes.</p>

Reproductive timing and investment decisions of a protogynous hermaphroditic coral reef fish species

<p>Life-history theory suggests that an organism must balance its available energy between two competing physiological processes to maximize fitness: reproduction and somatic growth. Energetic trade-offs are a fundamental concept of life history theory and form the basis of intra- and inter-specific variation in life-history strategies. In fishes, reproduction-growth trade-offs are an essential component of life-history optimization. This is particularly true for species with protogynous sex- change (the most common reproductive mode among coral reef fish species), where reproductive success rapidly and disproportionally increases with body size/ corresponding social status. In such systems, lifetime fitness is inherently linked to patterns of growth and energy allocation strategies determined by an individual’s size-specific rank within the dominance hierarchy. However, energy allocation strategies in a protogynous species may not only be a function of body size. Coral reef fish species are exposed to extremely variable environmental conditions and this can favour the evolution of strategies that utilize good times and avoid disadvantageous times for reproduction. Consequently, size- specific parental investment decisions may vary greatly in time and space according to environmental cues. My thesis focuses on the protogynous reef fish, Thalassoma hardwicke (the sixbar wrasse), which is extremely abundant on shallow coral reefs throughout the Indo-Pacific region. Specifically, I evaluate patterns of spawning and reproductive investment as a function of body size, social status, lunar phase and other environmental parameters. I address the question of whether females/males of differing size make different fitness-related decisions when away from spawning sites, and I evaluate context-dependency in these decisions. Finally, I will attempt to reconstruct the developmental histories (e.g., larval growth rates) of individuals from otoliths to evaluate potential relationships between developmental histories and fitness attributes.</p>