Exploitation Of Fishery Resources Research Articles

Binga's VaTonga communities involvement in Zambezi river fishery resource harvesting and management

Fishing dependent rural communities in developing countries are poor despite staying close to resources which can improve their lives. This motivated this study to assess the participation of Binga District communities in exploitation and management of fishery resources. A descriptive research design supported by both qualitative and quantitative research methods was employed. Questionnaires, interviews, focus group discussions and observations were used to collect data, and Microsoft excel 2016 was used for data analysis. Findings indicate that the VaTonga Communities of Binga (Basilwizi) District are not exercising their full fishing rights as expected because of a combination of lack of knowledge, failure of local authorities to represent local people in development policy designing, poverty and lack of transparency on expected management and exploitation rights of fishery resources. It was confirmed that all people wish to participate in fishing but strict access rights and poverty are major constraints. Main challenges faced by fishers include disruption of activities by crocodiles and hippos, poaching by foreign people and fish markets. Results showed that there is potential of livelihood improvement for people if their access rights are revised and if they are fully capacitated to exploit and protect their resources through community based natural resource management program. Unlike other studies in the same research domain, a framework for sustainable exploitation of fishery resources was developed as way forward. The framework recommends revision of access rights for local people and donor support to capacitate them with fishing resources amongst other aspects that need attention to improve socio-economic development and ecological integrity in the national thrust of leaving no one and no place behind towards achievement of global sustainable development goals. These findings will be an eye opener to policy makers with regards to the consequences of neglecting local people of ignoring them in decision making.

Complex dynamics of a fishery model: Impact of the triple effects of fear, cooperative hunting and intermittent harvesting

In natural ecosystems, predators often live in groups and have evolved cooperative hunting behaviors over time. This cooperative behavior on the one hand increases the success rate of the prey, but it also leads to the fear response of prey to predators, thereby affecting the reproduction rate of prey populations. In the current study, we put forward a fishery model for renewable aquatic resource with dual effects of fear and cooperative hunting, and investigate the impact of fear level and cooperative hunting intensity on the dynamics of the model. The analysis shows that the level of fear and the intensity of cooperative hunting can affect the existence and number of coexisting equilibria. Secondly, from the perspective of rational exploitation of fishery resources, we adopt a state-feedback intermittent fishing strategy, which fully considers the current status of the target species and avoids the impact of irrational fishing on the ecosystem. We investigate the dynamic behavior of the fishery model under discontinuous fishing model, including the existence and stability of predator-extinction periodic solution and co-existence order-1 and order-2 periodic solutions under different fishing thresholds, which not only provides a possibility to fishing species according to the period, but also ensures a certain robustness of the fishing strategy. Finally, the main results are verified by numerical simulations using MATLAB program and their biological implications are discussed.

Inventory and Dynamics of Fish Landings from Small-Scale Maritime Fisheries at the Fishing Port of the San-Pédro’s Port (South-West, Côte d'Ivoire)

Knowledge of the fish fauna in Ivorian waters is of concern to both scientists and those responsible for developing the fishing industry. Indeed, the increasing intensification of the exploitation of fishery resources is raising real risks of regression and disappearance of certain species. With this in mind, a survey of fishing activities was carried out in the fishing port of San-Pédro between July and December 2021. The aim of this study was to take stock of the dynamics of fish landings from small-scale fishing in this fishing port. Sampling of landed fish was carried out between 08:00 and 12:00 in the morning in two campaigns according to the two seasons that prevail in the region, by visual differentiation in plastic containers followed by counting. Identification was carried out using the appropriate keys. The conservation status and vulnerability of the various specimens were determined according to IUCN criteria version 2023. The inventory showed that a total of 55 species of fish from 32 families and 14 orders were landed during the two study periods. These catches were dominated by the order Perciformes, which was the most diverse (56.36% of species) and the most preponderant (61.29% of individuals). Oceanodromous species dominated the catches during the long rainy season. On the other hand, benthic species were the most common during the long dry season. Thunnus albacares was the most abundant during the long dry season, while Sardinella aurita (26.8%) dominated during the long rainy season. The analysis of conservation status and vulnerability showed that 18 species of fish landed were of biological interest for conservation. The presence of endangered species such as Rhinobatos cemiculus means that fishermen need to be made more aware of the problem and their catches need to be monitored more closely in order to protect them.

Promoting 4.0 Supply Chain Innovation for Fisheries Bioecoregion: A Case Study in West Java Province, Indonesia

The industrialization of marine and fisheries is the integration of production systems from upstream and downstream, to increase the scale and quality of production, productivity, competitiveness, and value added of fishery products. Bio-ecoregion-based fisheries and marine resources from each region, especially in West Java, which is one of the producers of fisheries and marine production through the development of industrialization innovations 4.0. This study aims to analyze how to promote 4.0 industrial innovations for Fisheries Bioecoregion, case study in West Java Province, Indonesia. The method used in this research is quantitative description, using primary and secondary data. Data analysis tools use SWOT to systematically analyze various factors based on logic that can maximize strengths and opportunities, but simultaneously can minimize weaknesses and threats. Based on the research results, the strength that is owned is to create a transformation of the potential of fishery resources to the exploitation of fishery resources based on Bioecoregion. Opportunities faced by the transformation of open market access management and high competitiveness in fisheries and marine products. The challenges faced must be able to create a digital bio-ecoregion-based fishing industry system. The threat faced by the transformation of the workforce towards digitalization. Based on the SWOT analysis being in quadrant 2 it means it is in a diversification strategy. Promoting 4.0 Industrial Innovations For a Fisheries Bioecoregion, based on: increasing the added value of fisheries industrialization, increasing the competitiveness of fishery products; strengthening of marine and fisheries industry players; commodity-based, regional, and regional management systems with a concentration on leading commodities, modernization of upstream and downstream production systems; balance between the use of natural resources and sustainable environmental protection; and changes in the mindset and behavior of modern society.

Comparison of Accounting Profit Between Offshore and Deep-sea Commercial Fishing Industry in Pahang State, East Coast of Peninsular Malaysia

Highlight Research Economic performance of commercial fishing industry in Pahang State, East Coast of Peninsular Malaysia. Comparison of accounting profit between the two prominent fishing gear types: trawlers and purse seine in Pahang State Comparison of accounting profit between the different zones of fishing operations by the trawlers and purse seine Research findings showed that trawlers give more profit than purse seine vessels in Pahang State and overcapacity and over exploitation is distinctly found in Pahang State commercial fishing industry. This study suggested that other analysis such as biological performance by this study area should be done in future coupled with the analysis of impact of management policies on the sustainability of the fishery. Abstract Marine capture fisheries in Malaysia plays prominent role in economic growth and commercial fisheries makes great contribution to country’s economy. The commercial fishing industry in East Coast of Peninsular Malaysia are mainly operated by trawlers and purse seines which rises a major concern in managing and achieving the goal of sustainable fishery. This study aimed to account the differences of accounting profit level in commercial fishing industry in Pahang State, East Coast of Peninsular Malaysia. In this study, comparison of accounting profits using revenue and profit approach among trawl and purse seine fishery in two different zones: Zone C (offshore) and Zone C2 (deep sea) was carried out based on the intensive survey on fishing capacity and other economic factors. The survey was carried out with the commercial fishermen and total respondents of 156 fishers at landing port. The result showed that trawlers incurred low cost yet provided higher profit than doses by purse seine. Moreover, there are more trawlers vessels operating in the Pahang state fishing ground and the open access nature of the fishery like larger profit invites more effort to use in the fishery which is leading to the over exploitation of fishery resources and threatening the sustainable condition of the fishery. The findings of the research inform the possible impact of fishing profit to overcapacity in sustainable fishery management in Pahang State fishery.

Analytical Studies on Ciguateric Fish in Okinawa, Japan (II): The Grouper Variola albimarginata

Ciguatera fish poisoning (CFP) refers to an illness caused by ingesting fish that have accumulated ciguatoxins (CTXs). CFP frequently occurs in the tropical and subtropical Indo-Pacific Ocean and the Caribbean Sea. In Japan, CFP occurs sporadically but constantly in Okinawa and the Amami Islands. The grouper Variola albimarginata is regarded to be safe for consumption. To assess the real risk of V. albimarginata, we analyzed 133 specimens of the fish in Okinawa using liquid chromatography–tandem mass spectrometry (LC–MS/MS). Ciguatoxin-1B, 54-deoxyciguatoxin-1B, and 52-epi-54-deoxyciguatoxin-1B were detected in 28 specimens (21%). In 11 of these specimens (8%), the CTX levels exceeded the US FDA guidance level (0.01 µg/kg CTX1B equivalent). However, only one fish (<1%) was found to have levels above the recommended level in Japan (0.175 μg/kg CTX1B equivalent). The amount of CTXs in the flesh (280 g) of the most toxic specimen (0.225 μg/kg) did not reach the level needed to cause illness. The CFP risk due to the consumption of this species was thus considered to be low in Okinawa, supporting local belief. The CTX levels in the flesh were positively correlated with standard length, body weight, and age. The total CTX levels significantly fluctuated between the male and the female of the species. The estimated annual catch of V. albimarginata in Okinawa and Yaeyama Islands was 4909 kg or 13,636 fish. As many as 1227 fish had levels over the US FDA guidance level, but only 136 fish had levels above the Japanese recommendation. Risk management based on the Japanese recommendation level seems to be effective in protecting public health and enabling appropriate exploitation of fishery resources.

Rebuilding Mediterranean marine resources under climate change

The Mediterranean Sea ranks among the most overexploited and fastest-warming ocean regions. This situation calls for urgent development of global change scenarios and models of marine biodiversity to anticipate changes and support ecosystem-based management strategies across the entire Mediterranean Sea. Using a new end-to-end modelling chain for the whole Mediterranean Sea, we explored the potential effects of changes in fishing pressure on marine resources and ecosystem structure and functioning under a worst-case climate change scenario (RCP8.5). We found that a decrease in fishing mortality or an improvement in fishing selectivity could increase the total biomass and total catch of high trophic level species by the middle and end of the 21st century, especially the biomass of demersal, large pelagic and benthic species, thereby reversing the projected climate-induced decrease in their biomass and catch by the end of the century in the western Mediterranean basin. In contrast, climate change could offer opportunities for some eastern Mediterranean fisheries to increase catches of thermophilic and/or exotic species benefiting from new favourable environmental conditions. Based on a suite of ecological indicators, our results indicated clear positive effects of a more sustainable fisheries management on ecosystem structure and functioning. However, a decrease in fishing pressure may not fully compensate for climate-induced changes on marine resources and ecosystems, but rather buffer some projected negative impacts. Our study highlights the need for a more sustainable exploitation of fisheries resources to restore marine ecosystems and increase their resilience in a global change context.

Evaluating the sustainability of fishery resources and fishing gears: Case study of Ngoyè and Elabè, Kribi, South Cameroon

Evaluating fishing methods and associated gears over the time is one key to understanding the sustainability of fisheries resources. Well-managed fishery is expected to use gear that catch most of the available species at sizes that do not undermine sustainability. This study investigates effects of two fishing gears used in two landing sites of Kribi and sustainable exploitation of fishery resources. The semi-direct survey included questionnaire interview from fishermen and direct observation of fishing gears at the time of operation was chosen to collect information. A total of 299 bottom-set gillnets with mesh sizes ranging from 15 mm to 100 mm and 17 beach seines were listed at both landing sites. Beach seine catches combined as well as pelagic, demersal or benthic species. Among the species caught, Ilisha africana was the dominant species followed by Pseudotolithus senegalensis, Pseudotolithus typus. Cath profile of bottom-set gillnet showed that Pseudotolithus typus, Pseudolithus senegalensis, and Cynoglossus sp. were the three dominant species. No growing stage is spared by the beach seine catches and the minimum size obtained was 4 cm for Selenne dorsalis and Pseudotolithus senegalensis. The reduction in size and relative high number of landed species result from pressure on fishery resources, non-compliance with regulations in terms of gear and fishing techniques.

Socio-economic impact of the exploitation of fisheries resources on the lives of fishing communities in Hébé, a lagoon village in the Sub-prefecture of Bonoua (ivory coast)

Socio-economic impact of the exploitation of fisheries resources on the lives of fishing communities in Hébé, a lagoon village in the Sub-prefecture of Bonoua (ivory coast)

Haor-Based Floodplain-Rich Freshwater Ichthyofauna in Sylhet Division, Bangladesh: Species Availability, Diversity, and Conservation Perspectives

Biodiversity assessment is important for evaluating community conservation status. The haor basin in Sylhet Division represents a transitional zone with high species availability, rare occurrences and endemism. As a result, this study aims to describe the haor-based freshwater fish composition, including habitat, trophic ecology, availability and conservation status. Semi-structured questionnaires were used to collect data on fish samples through focus group discussions, field surveys, and interviews with fisheries stakeholders on a monthly basis. We identified 188 morpho-species, of which 176 were finfish and 12 shellfish, distributed into 15 orders and 42 families where 29%, 42%, 15%, and 14% species were commonly available, moderately available, abundantly available, and rarely available, respectively. Cypriniformes was the dominant order in both total species and small indigenous species identified. Approximately 45.34% of species were riverine, 31.58% floodplain residents, 12.55% estuarine, 2.83% migratory, and 7.69% were exclusively hill stream residents. Carnivores and omnivores were the most dominant trophic groups. A total of 87.76% species were used as food, 12.23% as ornamental and 6.91% as sport fish. Approximately 50 species were threatened (7 critically endangered, 23 endangered and 20 vulnerable) at the national level, most of them belonging to Cypriniformes and Siluriformes. Based on endemism, 16 species were endemic of which Sygnathidae, Cobitidae, Olyridae, Cyprinidae and Balitoridae fell under the threatened category. Minimizing intense fishing efforts, banning indiscriminate fishing and destructive fishing gear, initiating fish sanctuaries and beel nurseries, and implementing eco-friendly modern fishing technology are suggested to conserve the threatened species. This study represents a guideline for assessing the availability and conservation of freshwater fish in the Sylhet belt and serves as a reference for decision-makers in order to allow for the sustainable exploitation of fisheries resources within an ecosystem-based framework.

Length-weight relationship of Parachanna obscura from Egbe Reservoir, Ekiti State, Southwest Nigeria

Length-weight relationship and condition factor play significant roles in fisheries management. The growth pattern and wellbeing of Parachanna obscura from Egbe Reservoir was evaluated employing length-weight relationship and Fulton’s Condition Factor (K). One hundred specimens of the fish were procured from artisanal fishermen between January and April, 2018. Fish were fixed in 10% Formalin and transported to the laboratory for data collection. Sex ratio for the fish samples was 1:1.33 in favour of male. The total length of the sampled fish ranged between 17.9 and 36.1cm. Fish weight ranged from 88.1 to 425.2g. The parameter ‘b’ for the fish was 2.359 in the Reservoir, denoting negative allometric growth pattern. The correlation coefficient (r2) was 0.571. Mean Condition Factor of the fish was found to be 0.938, thus indicating the suitability of the habitat to promote the wellbeing of the fish. Females appeared lengthier and heavier. Over seventy percent of the fish samples had lengths higher than the reported Lm50 for the species. The results of this study revealed that the fish appeared not threatened in the habitat and could therefore serve a basis for proposing management strategies for the exploitation of fisheries resources of the reservoir.

Variability of Biological Features of a Mugilidae Chelon Ramada in Two Tunisian Reservoirs

Mullet is the most massively harvested species, representing the third of the total freshwater fish landing in Tunisia. To ensure freshwater fish farming durability and development in the country, reservoirs have been stocked with Mugilidae fry which was collected from coastal and estuaries areas after a short adaptation period. The objective of this paper is to compare and contrast Chelon ramada’’s age, growth, and mortality in two Tunisian freshwater reservoirs (Seliana and Kasseb). The sample species were caught with a multi-mesh gillnets and were classified into five age groups. The study of the age and growth demonstrated variability between Chelon ramada species’ features. The optimal size of the captured mullet (Lopt) was equal to 37.62 cm for M=0.48, L∞=57.05 and K=0.31 in Siliana Reservoir. Whereas, it measured 31.42cm in Kasseb Reservoir, for M=0.795, L∞=48.15 and K=0.31. It has also been found that the fishing mortality rate is very high at Siliana Reservoir when compared to Kasseb Reservoir. This work is a contribution to the identification of the biological features of Chelon ramada that lives in Siliana and Kasseb Reservoirs. It seeks to ensure a rational and sustainable exploitation of fishery resources in these Tunisian freshwater reservoirs and it recommends the development and preservation of mullet fisheries.

FIRST DATA ON THE ICHTYOLOGICAL POPULATION OF A NEW HYDROELECTRIC LAKE: CASE OF THE DAM OF SOUBRE, COTE DIVOIRE

The new dam of Soubre in Cote dIvoire resulted in the creation of a 17.3 km2 lake in April 2017. After an 18-month ban, the exploitation of fishery resources started and is mainly carried out by foreignBozofishermen. The present study, whose main objective was to conduct the ichthyological inventory of this lake, was executed between August 2019 and July 2021. The artisanal catches of fishermen were examined monthly in the three main landing sites of the lake. The species richness of the lake was estimated at 42 species. The specific weight composition of the catches indicates the predominance of the catfish Chrysichthys nigrodigitatus with 16% of catches.For numerical abundance, the Mormyridae Marcusenius senegalensis leads the catches with a17% rate. It should be noted that this study allowed the observation of specimens of the freshwater shrimp of the genus Macrobrachium upstream of the lake, in the river-lake transition zone, while no individual of this species was captured in the lake.

Juridical analysis of the regulation of fishery resources in the Indonesian exclusive economic zone

As an archipelagic country, Indonesia has a wealth of living and non-biological natural resources, especially in its exclusive economic zone, specifically in this zone, there are an abundant wealth of fishery resources, but the economy and welfare level of traditional Indonesian fishers are still below the poverty line, in addition to the management of exploration and exploitation of fishery resources, Indonesia faces various problems, one of which is a problem with legal provisions. Therefore, researchers will analyze legal problems in managing fishery resources in this study's exclusive Indonesian economic zone. To answer the questions in this study, the authors used normative juridical research methods, and the results of the analysis were described using qualitative methods. After reviewing the literature, the study results indicate that legal problems in the fisheries sector are due to overlapping regulations and conflicting regulations. For this reason, in this study, the authors suggest the need to revitalize the law in the fisheries sector by harmonizing the law.

The role and value of science in shark conservation advocacy

Many species of sharks are threatened with extinction, and there has been a longstanding debate in scientific and environmental circles over the most effective and appropriate strategy to conserve and protect them. Should we allow for sustainable fisheries exploitation of species which can withstand fishing pressure, or ban all fisheries for sharks and trade in shark products? In the developing world, exploitation of fisheries resources can be essential to food security and poverty alleviation, and global management efforts are typically focused on sustainably maximizing economic benefits. This approach aligns with traditional fisheries management and the perspectives of most surveyed scientific researchers who study sharks. However, in Europe and North America, sharks are increasingly venerated as wildlife to be preserved irrespective of conservation status, resulting in growing pressure to prohibit exploitation of sharks and trade in shark products. To understand the causes and significance of this divergence in goals, we surveyed 155 shark conservation focused environmental advocates from 78 environmental non-profits, and asked three key questions: (1) where do advocates get scientific information? (2) Does all policy-relevant scientific information reach advocates? and (3) Do advocates work towards the same policy goals identified by scientific researchers? Findings suggest many environmental advocates are aware of key scientific results and use science-based arguments in their advocacy, but a small but vocal subset of advocates report that they never read the scientific literature or speak to scientists. Engagement with science appears to be a key predictor of whether advocates support sustainable management of shark fisheries or bans on shark fishing and trade in shark products. Conservation is a normative discipline, and this analysis more clearly articulates two distinct perspectives in shark conservation. Most advocates support the same evidence-based policies as academic and government scientists, while a smaller percentage are driven more by moral and ethical beliefs and may not find scientific research relevant or persuasive. We also find possible evidence that a small group of non-profits may be misrepresenting the state of the science while claiming to use science-based arguments, a concern that has been raised by surveyed scientists about the environmental community. This analysis suggests possible alternative avenues for engaging diverse stakeholders in productive discussions about shark conservation.

Addressing Cetacean–Fishery Interactions to Inform a Deep-Sea Ecosystem-Based Management in the Gulf of Taranto (Northern Ionian Sea, Central Mediterranean Sea)

Understanding of cetaceans’ trophic role and the quantification of their impacts on the food web is a critical task, especially when data on their prey are linked to deep-sea ecosystems, which are often exposed to excessive exploitation of fishery resources due to poor management. This aspect represents one of the major issues in marine resource management, and trade-offs are needed to simultaneously support the conservation of cetaceans and their irreplaceable ecological role, together with sustainable fishing yield. In that regard, food web models can represent useful tools to support decision-making processes according to an ecosystem-based management (EBM) approach. This study provides a focus on the feeding activity occurrence and the trophic interactions between odontocetes and the fishery in the marine food web of the Gulf of Taranto (Northern Ionian Sea, Central Mediterranean Sea), by zooming in on cetaceans’ prey of commercial interest. In particular, the quantification of trophic impacts is estimated using a food web mass-balance model that integrates information on the bathymetric displacement of both cetaceans’ prey and fishing activity. The results are discussed from a management perspective to guide future research and knowledge enhancement activities as well as support the implementation of an EBM approach.

Nonstationary Responses of Demersal Fishes to Environmental Variations in Temperate Waters of the Northwestern North Pacific under a Changing Climate

Although nonstationarity in marine ecosystems has attracted great attention, the nonstationary responses of demersal fishes to environmental variations induced by the changing climate are still not well understood. Here, we collected 21 time series of demersal fishes from 1956 to 2015 to investigate the climate-induced nonstationary responses in temperate waters of the northwestern North Pacific (NWP). We showed that these demersal fishes experienced state shifts in approximately 1986/87, accompanied by abrupt warming over this region. Moreover, the relationships between demersal fishes and sea surface temperature (SST) were found to change between the two identified eras (i.e., a weak relationship before 1986 and a strong negative relationship after 1986), which may be primarily caused by the alternating dominance of the East Asian winter monsoon and mega-ENSO on SST in temperate waters of the NWP. The identified climate-induced nonstationary responses of demersal fishes to SST variability in this study may provide implications for understanding climate-induced biological dynamics, predicting demersal fish fluctuations, coping with potential ecological risks, and the sustainable exploitation of fishery resources in the future climate. Note that the impact of fishing on the demersal fishes in temperate waters of the NWP was not assessed in this study due to the lack of fishing effort data and therefore the conclusions of our research should be approached with caution.

Study of Several Aspects of Fishery for Guiding Barrier Fishing Gear in The Coastal Town Palopo

Fishing is a profession that has long been carried out by humans and is estimated to have been thousands of years old. Sero is one of the many types of fishing gear that is often operated by coastal fishermen, especially in the Palopo City area. Fish, crabs, squids, lobsters, turtles and even estuarine crocodiles are just a few examples of variations in the types of marine life that can be trapped in sero fishing gear. Along with the growth of human population and advances in fishing technology, the level of exploitation is increasing. On the other hand, the carrying capacity of the environment, including fish resources, has limitations. The increasing number of fishing activities accompanied by the reduction of catch targets also causes competition between fishermen to compete for these resources often occurs. These things then motivated the author to conduct a scientific study in the hope that the results of this study can be one of the basis for the preparation of regulations, especially with regard to the use of sero-type fishing gear in Palopo City. The purpose of this research is to examine the existence of sero fishing gear in relation to potential conflicts, business contribution, types of catch, selectivity, and estimated catch to fishing effort. The research method used includes qualitative and quantitative analysis of several respondents who were selected either randomly (purpuse sampling) or based on a commonly used formula. The data obtained from the respondents are based on the results of interviews, both through filling out closed and open questionnaires. In addition to data from interviews, other necessary data are taken from government agencies, the results of previous research by experts, or taken directly at the research location. Based on the results of the study, the potential conflict between the use of sero fishing gear against other fishing gear users only has the potential to use traps, throwing nets, and hand lines. comparison of financing (R/C), and categorized quickly through analysis of return on investment (PP). The types of sero fishing gear caught consisted of 33 species of fish, 7 species of crustaceans, and 1 species of mollusk. The variety of species caught also proves the level of selectivity of fishing gear sero fishermen in Palopo City is categorized as medium based on species diversity analysis (H') and low category based on dominance analysis (D). The results in this study also prove that the level of selectivity of fishing gear sero fishermen in Palopo City is very low even though the level of exploitation of fisheries resources in Palopo City is actually still in the developing stage. Things that can be recommended based on the results of this study are the efficiency of the number of sero fishing gear and the use of mesh sizes as well as increasing efforts to conserve mangroves as a source of primary productivity.

Impacts of El Niño(2007) and La Niña(2015) events on spatial and temporal distribution of potential habitat of <italic>Scomber japonicus</italic> in the East China Sea

Chub mackerel <italic>Scomber japonicus</italic> is one of economically important fish species in the ocean, and it is also an important fishing target for Chinese distant-water fishery. The resources of <italic>Scomber japonicus</italic> are strongly affected by environmental changes, thus understanding the response of changes in the habitat suitability of <italic>Scomber japonicus</italic> in the East China Sea to different anomalous climate conditions can help better know the stock dynamics of its resources and fishing grounds, and make sustainable exploitation of fishery resources of <italic>Scomber japonicus</italic>. According to the fishery data of <italic>Scomber japonicus</italic> obtained from National Data Center for Distant-water Fisheries of China at Shanghai Ocean University, combined with three key environmental factors: sea surface temperature (SST), sea surface height (SSH) and net primary productivity (NPP), this study investigated and compared the differences in the habitat of <italic>Scomber japonicus</italic> in the East China Sea between 2007 (a La Niña year) and 2015 (an El Niño year), based on the method of arithmetic average habitat suitability index (HSI) modeling analysis. The results showed that the catch, fishing effort and CPUE (catch per unit effort) of <italic>Scomber japonicus</italic> in the La Niña year (2007) was higher than those in the El Niño year (2015). The latitudinal gravity centers of fishing ground (LATG) in 2007 were in the northern waters compared with that of 2015. Comparing the environmental conditions between the two years, it was found that the spatial distributions of SST, SSH and NPP from July to September in 2007 were significantly different from those in 2015. The habitat modeling analysis indicated that the environmental conditions in 2007 were favorable for the formation of high-quality habitat for <italic>Scomber japonicas</italic>. Moreover, the areas of suitable habitat (HSI>0.6) from July to September in 2007 were significantly larger than that in 2015, and the location of suitable habitats in 2007 was northward compared with 2015, leading to the LATG in 2007 more northerly. Our findings suggested that La Niña and El Niño events strongly affected the ranges and spatial distributions of suitable habitats of <italic>Scomber japonicus</italic> in the East China Sea and the impacts showed large differences under different climate variabilities.

Assessment of cetacean\u2013fishery interactions in the marine food web of the Gulf of Taranto (Northern Ionian Sea, Central Mediterranean Sea)

The exploitation of fishery resources acts as a driving force on cetaceans both directly, by determining their fishing mortality or injury as by-catch species, and indirectly, through the lowering the availability of their prey. This competitive overlap between fishing and cetaceans often results in inadequate solutions so that in some cases there have been cases of intentional cetacean culling to maximize fishing production. A modelling approach applied to investigate the ecological roles of cetaceans in the food web could prove more effective to integrate ecological and fishing aspects and to provide suggestions for management. The comparative analysis carried out in the Gulf of Taranto (Northern Ionian Sea, Central Mediterranean Sea) showed that fishing exploitation provides impacts on the investigated food web greater than those due to cetacean predation. Trawling was estimated to be the most negatively impacting fishing gear considering the mortality rates and consumption flows. On the other hand, the striped dolphin was the main impact on the food web due to its highest consumption flows. Analysis showed a negative and non-selective impact on the exploited species due to the fishing gears, while the odontocetes proved to select their prey species and provide a positive impact in the assemblage. In particular, while the fishing gears are primarily size selective, targeting mostly large and economically valuable fish, the odontocetes seem to follow a co-evolution process with their prey, developing a specialization in their resources, providing control of the meso-consumers and ensuring a trophic stability in the ecosystem.