Fishing Areas Research Articles

Aligning bottom-up initiatives and top-down policies? A comparative analysis of overfishing and coastal governance in Ghana, Tanzania, the Philippines, and Thailand

As coastal communities across the Global South confront the multiple challenges of climate change, overfishing, poverty and other socio-environmental pressures, there is an increasing need to understand diverse coastal governance responses and livelihood trajectories from a comparative perspective. This paper presents a holistic investigation of the pressures coastal communities face in four countries and examines possible meeting points between bottom-up initiatives and top-down policies. We compare the experiences of eight fishing areas in Ghana, Tanzania, Thailand and the Philippines and ask how small-scale fishing communities perceive overfishing and other socio-environmental pressures; what factors determine the success and failure of coastal governance initiatives; and how different initiatives can be made congruent to improve coastal, rural development outcomes. Results from an extensive survey of 835 fisherfolk and semi-structured interviews with 196 key informants show that overfishing remains a significant driver of livelihood trajectories in the communities and that fisherfolk respond through informal mechanisms of collective action. Drawing from these diverse experiences, we propose viewing coastal livelihood trajectories through the integrated dimensions of socio-environmental relationships and coastal governance options and discuss implications that address institutional scalar flexibility, illegal fishing, and persistent marginalisation.

Culinary Business Management Strategy Through Fish-Based Food Processing Training in Randusari Village, Semarang District

Randusari Village is part of the Semarang sub-district, the city of Semarang, which is a coastal area. Agrarianly as a producing area of marine fish and brackish water fish. As an effort to utilize fish that can increase family income, namely by playing a culinary business management, through fish-based food processing training. The objectives of the activity are 1) to provide information on culinary business management. 2) developing innovative fish-based food products. The benefits provided are efforts to improve the family economy and information on processed fish innovations that have selling value and nutritional value. The method of activity is lectures and demonstrations of fish-based food processing. The service activities were carried out in the Randusari Village hall, with 30 housewives participating. The results obtained by participants were that 85% received increased information about business planning, business implementation, and culinary business marketing. The demonstration resulted in processing fish into: pindang dumplings, catfish dragon legs, spicy fish bakpia, bandeng zuppa soup, tilapia rolls filled with vegetables, bandeng rolls, catfish satay lilit. The fish-based food products are expected to be marketed at the Tiban market, which is open every Sunday, and is managed by residents. The next hope is that the product can be marketed more broadly, and can add variants of souvenir products in the city of Semarang.

GAM (Generalized Additive Model) Analysis for Predicting Potential Area of Lemuru in Bali Strait

Lemuru is a potential fish in the Bali strait with 80% of the total catch. The fishing process is determined by the efficiency and effectiveness of improving the fishing area. However, the lack of awareness of fishing areas by fishermen tend to be less optimal, waste of time and fuel. One of the alternatives is to use remote sensing data. Fishing areas information can be obtained through oceanographic parameters. Sea surface temperature and chlorophyll-a are main factor determined fishing areas. This study aims to predict the fishing area of S. lemuru using GAM (Generalized Additive Model) analysis, the results of this model can show a range of oceanographic factors that significantly explain high fishing related to marine environmental parameters. Fishing data and coordinates were obtained from PPP Muncar, Banyuwangi on May 2021. Data used is from fishing data around two years in Bali strait. The optimum value of chlorophyll-a Lemuru fishing is at 0.1- 1.2 mg m -3 and sea surface temperatures around 27 - 31°C. According to GAM statistical modelling, the most appropriate fishing area was data combination among data fishing, sea surface temperature of AIC and CDE AIC around 23044.21, and CDE 8.18%. The whole area of Bali strait is Lemuru fish distribution yet located in different areas each season such as west season at latitude (-8.26°)-(-8.59°) longitude (114.466°)-(114.449°), east season at latitude (-8.74°)-(-8.70°) longitude (114.299°)-(114.187°), while in transition season 1 at latitude (-8.50°)-(-8.78°) longitude (114.819°)-(115.070°) and season 2 at latitude (-8.27°)-(-8.56°) longitude (114.742°)-(114.819°

Country of origin label monitoring of musky and common octopuses (Eledone spp. and Octopus vulgaris) by means of a portable near-infrared spectroscopic device

Modern analytical techniques using miniaturized and portable near infrared (NIR) spectroscopy instruments are particularly suited for assessing the authenticity of fishery products since meeting the requirements of rapidity, eco-friendliness, cost-effectiveness, and easiness of application. The objective of the present study was to verify the suitability of use of a portable and ultra-compact NIR spectrometer combined with machine learning to characterize the geographic origin of two octopus species. Replicate NIR spectra (908.1–1676.2 nm) of 118 musky and 29 common octopus specimens (Eledone spp. and Octopus vulgaris) from Portuguese Atlantic or Spanish Mediterranean fishing areas were recorded, pre-processed and elaborated via the following classification algorithms: orthogonal partial least square discriminant analysis (OPLS-DA), logistic regression (LR), random forest (RF), support vector machine (SVM), and multilayer perceptron-artificial neural network (MLP-ANN). When 7-fold cross validation was performed on 75% of data, the results showed that linear tools (OPLS-DA and LR) were the most powerful and stable techniques in recognizing the origin of both octopus species (mean sensitivity, specificity, accuracy, and precision values above 98%). During the external validation phase OPLS-DA, SVM, and MLP-ANN performed better for common octopuses, while LR and MLP-ANN for musky octopuses. The achieved outcomes suggest the combination of portable NIR spectroscopy and machine learning as a promising plan of action to be adopted for the creation of an integrated analytical platform with capabilities for automated data recording, processing, and reporting, which may be helpful for on-site and in-line monitoring of fishery products.

Результаты гидроакустических исследований байкальского омуля (Coregonus migratorius) на рыбопромысловых акваториях озера Байкал с использованием отечественных информационных разработок

After many years of interruptions, sonar surveys of the main fishing areas of Lake Baikal were carried out: Selenginsky shallow water and Northern Baikal. When performing hydroacoustic research and data processing, a Simrad EY500 scientific echo sounder with a frequency of 70 kHz and with an ES 70-11 antenna (split beam), a domestic GIS "CartMaster" with a hydroacoustic database was used. In the area of the Selenginsky shallow water, accumulations of omul were recorded in the depth range from 70 to 300 meters. In the water area of 145,010 hectares, the number of omul was 11386970, and its biomass was 4108 tons. The maximum registrations of omul accumulations per unit of distance traveled on Northern Baikal were higher compared to the Selenga shallow water. The densest accumulations of omul were recorded in the depth range from 120 to 250 meters. In the water area of 14695 hectares, the number of omul was 6370,540, and its biomass was 992 tons.
 The results of hydroacoustic surveys turned out to be comparable with the results of biological studies and on the basis of which it can be assumed that the decline in abundance and biomass has stopped. There is an increase in spawning herds and the number of larvae, which means that we can expect an increase in the total biomass in the foreseeable future.

Spatial and temporal catch concentrations for Antarctic krill: Implications for fishing performance and precautionary management in the Southern Ocean

The undergoing rapid climate changes recorded along the Western Antarctic Peninsula (WAP) in combination with the increasing seasonal catches reported by the krill fishery have raised concerns as to whether the management strategy established by the Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR) is effectively avoiding impacts on the krill stock and related ecosystem.Despite the current fixed catch limit being spread across fishing areas to reduce spatial catches concentrations, our 38-year analysis revealed the highest historical spatial (ton/km2) and temporal (ton/day) fishing concentration levels across the WAP and South Orkney Islands. Higher seasonal catches in recent decades removed persistently within the same small fishing areas and during shorter fishing seasons are key factors influencing this situation.We used the catch per unit effort (CPUE) as a measure of fishing performance. CPUE was standardized using a GAMM model taking into account operational factors such as fleet composition, trawling methods, seasonality and daily catches, and we detected negative CPUE trends over time and across the different fishing areas. Our results suggest that the fishing performance have responded to the elevated spatio-temporal fishing concentration and changes in sea-ice. We discuss whether the negative CPUE trends are caused by fishing-induced depletion or driven by other factors such as krill flux, reduction and contraction of krill abundance and increased cetacean foraging (due recovery of whale populations). Finally, we also highlight the need to expand the survey's coverage (by acoustic or net-based methods) to the new, highly fished, and non-monitored areas such as Gerlache Strait, which is an important area for krill and dependent predators.

Effects of fish meal replacement with Chlorella meal on growth performance, pigmentation, and liver health of largemouth bass (Micropterus salmoides)

Chlorella meal is a potential protein source for aquafeeds. However, the physiological response of carnivorous fish fed Chlorella meal remains elusive. This study evaluated the effects of replacing dietary fish meal with Chlorella meal on growth performance, pigmentation, and liver health in largemouth bass. Five diets were formulated to replace dietary fish meal of 0% (C0, control), 25% (C25), 50% (C50), 75% (C75), and 100% (C100) with Chlorella meal, respectively. Total 300 fish (17.6 ± 0.03 g) were randomly assigned to 15 tanks (3 tanks/group). Fish were fed the experimental diet twice daily for 8 weeks. The increased dietary Chlorella meal quadratically influenced the final body weight (FBW), weight gain rate (WGR), specific growth rate (SGR), and feed intake (FI), which were significantly lower in the C100 group than in the other groups (P < 0.05). The feed conversion ratio (FCR) increased linearly or quadratically with dietary Chlorella meal. Dietary Chlorella meal linearly or quadratically increased the lutein content of plasma, liver, and dorsal muscle of largemouth bass (P < 0.05). Compared to the C0 group, all supplemented Chlorella meal groups significantly improved the yellowness (b∗) of the dorsal body (1.5 to 2.0 fold), abdominal body (1.5 to 1.8 fold), and dorsal muscle (3.8 to 5.4 fold) of largemouth bass (P < 0.05). In addition, compared to the C0 group, the liver vacuolation area of fish was significantly increased in the C75 and C100 groups (P < 0.05). Transcriptional levels of apoptosis-related genes of β-cell lymphoma-2 (bcl2), caspase-9-like (casp9), and caspase-3a (casp3) were markedly upregulated (0.9 to 1.6 fold) in the C100 group compared to the C0 group (P < 0.05). Based on the quadratic regression analysis between FBW, WGR, or SGR and dietary Chlorella meal level, largemouth bass had the best growth when replacing 31.7% to 32.6% of fish meal with 15.03% to 15.43% dietary Chlorella meal. The present results indicated that dietary supplementation with Chlorella meal (11.85% to 47.45%) significantly enhanced the pigmentation; however, total replacement of fish meal (40%) with Chlorella meal (47.45%) caused growth retardation, apoptosis, and liver damage in largemouth bass.

Contrasted spatio-temporal changes in the demersal fish assemblages and the dominance of the environment vs fishing pressure, in the Bay of Biscay and Celtic Sea

Climate change and resource exploitation represent strong selection pressure affecting the spatio-temporal dynamics of marine assemblages that ensure food provision for humans. However, such dynamics remain poorly documented, and their drivers unclear. Here, we investigate changes in fish assemblages of two key European fishing areas, the Bay of Biscay (BoB) and the Celtic Sea (CS), during the last two decades. We quantify the relative contribution of change in energy (i.e. temperature and trophic resources), habitat (depth, substrate, oxygen) and fishing pressure to explaining observed spatial and temporal variations in fish diversity. We used long-term scientific surveys to evaluate the spatio-temporal changes in species richness (SR), abundance and composition of demersal fish (Actinopterygii) assemblages at different spatial scales combined with a range of regression models and variance partitioning. Diversity patterns showed greater variability in space than in time: SR weakly changed over time, while compositional dissimilarity showed local patterns of taxonomic homogenization in the CS and differentiation in the southern BoB, where local assemblages were becoming more similar and dissimilar over time, respectively. Energy funnelled through small pelagic species as a potential trophic link affecting the dynamics of demersal assemblages was the most important driver, while habitat and fishing pressure had limited importance. Our study revealed contrasted dynamics of demersal fish assemblages at a regional scale that were best explained by the dynamics of small pelagic species. Direct effects of environmental forcing and fishing pressure were limited in both regions which have a long history of fishing and still remain relatively buffered from global warming effects. This research paved the way to combine methods inspired by biogeography with scientific monitoring surveys to detect spatio-temporal dynamics of fish assemblages and their drivers in marine ecosystems under multiple pressures.

Distribution of anisakid nematodes in the muscle tissue of cod (Gadus morhua) from the Norwegian Sea

Atlantic cod (Gadus morhua) is an important commercial fish species on the world market. The aim of our studies was to explore the presence, intensity of infection and distribution of the zoonotic nematodes of the different genera of Anisakidae in the muscle tissue of G. morhua from the Norwegian Sea. Cod from fishing areas FAO IIa1 (n = 50) and FAO IIa2 (n = 56) were sampled in March 2017. The unskinned flesh of each fish was examined using a white-light transilluminator. Collected parasites were identified to the genus level, and a subsample was identified using molecular methods. We found a higher prevalence of infection with Anisakis than with Pseudoterranova in the musculature of cod from both fishing areas. In FAO IIa1, a lower prevalence of infection with Pseudoterranova was recorded (14%) than in FAO IIa2 (∼39%). However, the intensity of infection was higher (53) in FAO IIa2 than in FAO IIa1 (8 parasites per fish). The opposite was found with Anisakis (prevalence 88% in FAO IIa1 and ∼55% in FAO IIa2, intensity up to 30 and up to 25 parasites per fish respectively). Most Anisakis larvae were present in the belly flaps (predominantly the left side), while Pseudoterranova spp. were dispersed with descending frequency in belly flaps, dorsal fillet and caudal fillet. Molecular identification revealed the presence of A. simplex (s.s.), P. decipiens (s.s.) and P. krabbei in both areas, and a hybrid of P. decipiens and P. krabbei in FAO IIa2.

SKIPJACK TUNA FISHING SEASON AND ITS RELATIONSHIP WITH OCEANOGRAPHIC CONDITIONS IN PALABUHANRATU WATERS, WEST JAVA

Skipjack tuna (Katsuwonus pelamis) is the main catch species in Indonesian Palabuhanratu waters. The dynamics of skipjack fishing areas are influenced by oceanographic parameters such as sea surface temperature and chlorophyll-a concentration. This study aims to predict the skipjack fishing season, analyze the dynamics of oceanographic conditions, especially the distribution of sea surface temperature and the distribution of chlorophyll-a, and determine the relationship between skipjack fishing season and the dynamics of the distribution of sea surface temperature and the distribution of chlorophyll-a in the waters of Palabuhanratu, West Java. Catch per unit effort analysis was used to determine the fishing season index, while the dynamics of sea surface temperature and distribution of chlorophyll-a were analyzed from MODIS image data. The results showed that skipjack fishing season in Palabuhanratu waters was from July to November. Monthly sea surface temperatures range from 26-30℃ with an average value of 29℃. The distribution value of chlorophyll-a concentration ranged from 0.09 mg/m3 to 0.51 mg/m3 with an average value of 0.23 mg/m3. Skipjack tuna production tends to increase when sea surface temperatures are low and chlorophyll-a concentrations increase.

Assessing Conservation and Management Actions with Ecosystem Services Better Communicates Conservation Value to the Public

Abstract Fish and wildlife populations are under unprecedented threats from changes in land use and climate. With increasing threats comes a need for an expanded constituency that can contribute to the public support and financial capital needed for habitat conservation and management. Using an ecosystem services approach can provide a framework for a more holistic accounting of conservation benefits. Our objective here is to provide a greater understanding of the role that taking an ecosystem services approach can have in expanding the public constituency that supports the use of financial capital required to conserve and manage the nation's natural capital. To demonstrate a methodology and the usefulness of taking an ecosystem services approach when communicating the value of conserving and managing fish and wildlife habitats, we performed an evaluation of U.S. Fish and Wildlife Service-owned Waterfowl Production Areas, National Wildlife Refuges, and easement lands (both wetland and grassland) in Stutsman County, North Dakota. We quantified amphibian habitat, grassland bird habitat, floral resources for pollinators, and carbon storage services under various scenarios of conservation. While we did not include all possible ecosystem services in our model, our case study shows how this process can provide a more complete picture of the collateral benefits of conservation directed primarily toward waterfowl. Using this ecosystem services approach, we documented marked losses in all services modeled if current conservation lands were developed for the production of agricultural crops. By having access to a more complete picture of benefits provided by conservation lands, decision makers can better communicate their value. By garnering greater public support through a more accurate accounting of societal benefits, conservation and management of dwindling natural capital may someday attain the same level of thought and consideration that is put into the conservation and management of the nation's financial capital.

Preventive measures to ensure the sea fishing regime

Marine areas that contain living resources are subject to international protection; their species, one of which is the maritime economic zone, have a special legal status: they can be marine - fishing and territorial areas of general&#x0D; purpose. The legislation of Ukraine actualizes the problem of environmental protection, creation of conditions of inviolability of law enforcement activity of a set of norms of various branches of law.&#x0D; The general causes and conditions of environmental crime are in the system of contradictions that arise from the interaction of man, society and nature. Their essence is that society, being part of the biosphere, resists the ecosystem due to limited opportunities for nature.&#x0D; The growth of environmental crime is facilitated by the shortcomings of current legislation and its protection by relevant government agencies, the lack of mechanisms for its effective implementation.&#x0D; Within the zones of general definition, the laws of Ukraine apply to all offenses. Such a zone is recognized as the territory of the respective state and the laws apply to persons who have committed the relevant offenses. In this case, there may be peculiarities in the application of laws that contain a blanket disposition. An example is environmental offenses, the responsibility for which is based on other regulations. In the conditions of such zones, the corresponding normative acts have specifics which distinguish their application in the territory of other states.&#x0D; Within the exclusive (marine) economic zone, coastal states have the right to carry out exploration, development, management of natural resources, to exercise jurisdiction over the conservation of the marine environment, to conduct marine research

Diversity, distribution and extinction risk of native freshwater fishes of South Africa.

Extinction risk for 101 valid species and 18 unique genetic lineages of native freshwater fishes of South Africa was assessed in 2016 following the IUCN Red List criteria. An additional five species (three new species that were described and two species that were revalidated subsequent to the 2016 assessments) were assessed in the present study. A synthesis of the outcome of the assessments of the 106 valid species and 18 genetic lineages indicates that 45 (36%) of South Africa's freshwater fish taxa are threatened (7 Critically Endangered, 25 Endangered, 13 Vulnerable). Of the remaining taxa, 17 (14%) are listed as Near Threatened, 57 (46%) are Least Concern and five (4%) are Data Deficient. More than 60% of the endemic taxa are threatened. The Cape Fold Ecoregion has the highest proportion of threatened taxa (67%) due to the existence of a unique assemblage of narrow-range endemic species. Galaxias and Pseudobarbus have the highest number of highly threatened taxa as most of the species and lineages in these genera are classified as either CR or EN. Major threats to the native freshwater fishes of the country are invasive fish species, deterioration of water quality, impoundments and excessive water abstraction, land use changes and modification of riverine habitats. Immediate conservation efforts should focus on securing remnant populations of highly threatened taxa and preventing deterioration in threat status, because recovery is rare. Accurate delimitation of species boundaries, mapping their distribution ranges, improved knowledge of pressures and long-term monitoring of population trends need to be prioritised to generate credible data for the 2026 IUCN threat status assessments and designation of important fish areas as part of the National Freshwater Ecosystem Priority Areas (NFEPA) initiative.

Fish-spawning channels are a means of improving the conditions of natural reproduction of populations of anadromous fish on regulated rivers

The relevance of the development is predetermined by the need to solve the problem of creating conditions for the natural reproduction of commercial stocks and the restoration of populations of passable, semi-passable and aquatic fish in the conditions of river flow regulation carried out by the construction of cascades of waterworks on them. One of the ways to solve this problem on the Lower Don is the creation of near-hydro-node fish-spawning channels that provide conditions for the passage and spawning of anadromous-migrating fish. When designing such structures, specialists feel a lack of information and recommendations on the technical justification of their layout and design solutions. This circumstance predetermined the purpose of the study, which consists in summarizing information and evaluating the layout and design solutions of the Nikolaev, Konstantinovsky, Bagaevsky and Kochetovsky fish-spawning channels (FSCs) and developing proposals for their improvement. The factual basis of the development was made up of the materials of the survey of existing and analysis of projects of fishspawning channels on the Lower Don low-pressure waterworks. Based on the materials of the survey and analysis, the schemes of their layout and design solutions, flow-rate parameters and geometric dimensions were established, the advantages of fish-spawning channels over other types of fish-passing structures were determined. Based on the materials of the survey of existing structures, the disadvantages of their layout and design solutions were found, consisting in the remoteness of the entrances to the channels from the dams, excessive flow rates in their tracts, the absence of recreation areas for fish, the inability to regulate the values of speeds attracting fish with changing water levels in the river, the lack of equipment of the entrance heads, the failure of the technical execution of the channel coating and elements of enhanced roughness. The directions of improving the layout and design solutions of the channels in terms of eliminating their shortcomings in the projects of the Bagaevsky and Kochetovsky waterworks are determined. The evaluation of design solutions is given and generalizations are made to determine the parameters of channels and their layout and design solutions, which are recommended to be taken into account and used in their design.

Proactively averting the collapse of Amazon fisheries based on three migratory flagship species.

Migratory species are the most important commercial fishes in the Amazon. They are also now the most threatened directly by some combination of overfishing, floodplain deforestation, and dam construction. Limited governmental monitoring and implemented regulations impede adequate management of the fisheries at adequate scale. We summarize the current stock status of the three most heavily exploited long-distance migratory species, which are two goliath catfishes (Brachyplatystoma rousseauxii and B. vaillantii) and the characiform Colossoma macropomum. In addition, we analyze impacts beyond overfishing on these species. Our results indicate: (i) the overfishing trends for these important species are either ominous or indicate the verge of collapse of the commercial fisheries based on them, and (ii) a dangerous synergy between overfishing, hydroelectric dams, and floodplain deforestation further challenge fisheries management of migratory species in the Amazon. We propose eight direct governmental actions as a proactive approach that addresses the main impacts on the fisheries. We consider that the most practical way to assess and manage overfishing of migratory species in the short run in an area as large as the main commercial fishing area in the Amazon is at market sites where enforced regulations can control fish catch. The management of the three species considered here has implications beyond just their sustainability. Their management would represent a paradigm shift where the governments assume their legal responsibilities in fishery management. These responsibilities include regulation enforcement, data collecting, inter-jurisdictional cooperation to protect migratory species at realistic life history scales, mitigation of the Madeira dams to assure goliath catfish passage to the largest western headwater region, and recognition of monitoring and managing wetland deforestation for the protection of fish and other aquatic and terrestrial biodiversity.

Elemental fingerprinting of thornback ray (Raja clavata) muscle tissue as a tracer for provenance and food safety assessment

The verification of food authenticity and provenance is a complex task and has raised public concern in recent years due to multiple episodes of food fraud and potential risks to consumers. In this sense, the evaluation of multi-elemental signatures is increasingly applied to confirm and validate the site of origin of animal products. Yet, we lack understanding of its efficacy for mobile organisms such as fish. Using multi-element Total Reflection X-ray Fluorescence (TXRF) analysis of muscle of thornback ray Raja clavata we successfully identified the fishing area of individuals collected in four areas along the Portuguese Atlantic coast (Atlantic Iberian waters, Northeast Atlantic). Overall, As, Fe, Sn, V and Zn presented higher contributions to discrimination (especially Fe and Rb for neighbouring collection areas), whilst the higher concentration elements (Na, K, P, S, Ca, Cl, Br and Sr) had similar concentrations among locations. Rays captured in the two areas with higher urbanization/industrialization presented higher concentration of elements associated with anthropogenic activities (such as As, Zn, Sn and V). In terms of food safety, only 0.9% and 2.8% of the individuals surpassed the recommended thresholds values for human consumption for Hg and Cd respectively. A canonical analysis of principal components resulted in classification accuracy of thornback ray to collection site of 56.7–84.2% (depending on site), with an overall accuracy of 65.1% over c. 500 km of coast in the Northeast Atlantic.

Impact of fuel subsidies on bottom trawl fishery operation in China

Fishery fuel subsidies reduce the cost of fishery production, promote the continuous expansion of the fishing vessel scale and fishing intensity, lead to overfishing, and eventually result in the deterioration of fishery resources. Based on survey data from Rongcheng, Xiangshan and Beihai, China, in 2018 and 2019, this paper analyzes the cost-benefit, break-even and sensitivity of bottom trawlers to explore the impact of fuel subsidies on bottom trawl fishery operations in China. The results show that the fuel expenditure is the biggest production cost of bottom trawl fishery. The fishery fuel subsidies are crucial to most bottom trawling economies. With fuel subsidies, the break-even operation ratios of bottom trawlers in all three fishing areas are below 100%, and trawler operations are profitable. Without fuel subsidies, only Xiangshan’s trawler operation is in a safe range and can continue to operate. The results of the sensitivity analysis show that the catch price and the fuel cost are the top two sensitivity indexes and the two most important determinants of net profit in the bottom trawl fishery operation. Without fuel subsidies a large number of bottom trawlers will withdraw from fishing and decrease fishing effort, thereby reduce the current threat to fish stocks.

Identifying three-dimensional swimming corridors for fish to match their swimming characteristics under different hydropower plant operations: Optimization of entrance location for fish-passing facilities

Fish that require migration are often diverse in the dam-built river, and some of them are benthic. For fish to pass efficiently across the dams, it is necessary to identify the swimming corridors and possible cluster areas of the target fish. However, previous studies have only predicted the two-dimensional swimming corridors of a single species. In this study, the relationships between the swimming behaviours of different species of fish and the three-dimensional (3D) hydrodynamic field were determined, and a model of the 3D swimming corridors corresponding to the fish swimming characteristics was constructed. The model was verified by a fish acoustic telemetry experiment. By simulating the river 3D hydrodynamic field in different scenarios, the possible swimming corridors and clustering areas of the target fish were further evaluated. We showed that the swimming corridors of the target fish were different among different scenarios, and the swimming corridors were mainly concentrated on both sides of the mainstream. With increased flow due to power station operation, the proportion of potential swimming corridors of target fish throughout the basin gradually decreased, and the proportion of velocity barrier zones of target fish gradually increased. By analyzing the possible swimming corridors of the target fish, the slow-flowing areas near the suddenly narrowed swimming corridors were considered to be the areas of target fish clustering. The cluster areas of the target fish weres also the optimal choice of the fish passing facility entrances, so as to ensure the best fish-crossing effect. The reliable and quantitative 3D fish swimming corridors model proposed in this study can provide a scientific basis for the layout of fish-crossing facilities and facilitate the scientific operation and management of the reservoir in the fish spawning season.

Law Enforcement Against Unreported Fishing: What Does Beyond the Catch Record?

Transparency is significant in highly migratory fisheries. The reliability of the catch data is essential for decisions of internationally agreed targets. Nevertheless, the data accuracy will much depend on each state's performance. Focusing on unreported catches of migratory fish, this study highlights the Thunnus Macoyyi (Southern Bluefin Tuna) fishing in Indonesia, as this fish species had experienced for being the limelight of unreported fishing allegations. The main objective is to reveal what are the difficulties that Indonesia is facing on its responsibility to maintain the accuracy of the catch record. Accordingly, the study examines two points by applying the pure legal method and doctrinal approach. Firstly, the international legal framework towards unreported fishing by analysing three main instruments such as the UNCLOS 1982, the UNFSA 1995, and the CCSBT policies. Secondly, it examines Indonesia law enforcement as a State party of regional fisheries organisation. It argues that the international authority could not be completely extended to a State's domestic fishing area. Thus, it gives more discretion to the national law to enforce compliance. Lesson learned from the case study of Indonesia's southern bluefin tuna contributes to unreported fishing literature and allows us to expose the legal gap remained in managing highly migratory fish stocks.

Genetic recruitment patterns are patchy and spatiotemporally unpredictable in a deep-water snapper (Lutjanus vivanus) sampled in fished and protected areas of western Puerto Rico

Genetic recruitment patterns are patchy and spatiotemporally unpredictable in a deep-water snapper (Lutjanus vivanus) sampled in fished and protected areas of western Puerto Rico