Following victory in the Russo-Japanese War, the Meiji government sought to expand its maritime influence in Northeast Asia by developing pelagic fisheries in the newly acquired Kwantung leased territory, but it encountered immediate resistance from the Qing court, which had just embarked upon ambitious reform to strengthen maritime defence through the building of a national fishing industry. The dispute first emerged as a clash between Japanese and Chinese fishery protection companies on the seas adjacent to the Chinese city of Xiongyue. It then gave rise to a protracted Sino-Japanese legal debate on the question of whether the Xiongyue fishing ground was in the free sea or part of Chinese territorial waters. However, the 1912 settlement agreement made no mention of the legal status of the fishing ground. By examining this oft-neglected dispute, this article not only provides a rare East Asian case that illustrates the tension between the requirements of national sea borders and the principle of navigational freedom, but also explores how the Meiji and Qing governments perceived and practised international maritime law at the turn of the twentieth century. It argues that neither government viewed international maritime law as the only referential framework to solve the dispute, especially when it contributed little to the conflict settlement and contradicted their perceptions of the historical relations between East Asian countries.

For Greater Scaup Aythya marila, classified as ‘Vulnerable’ on the European Red List of Birds, the south-western Baltic Sea is one of the most important wintering sites in Europe. In this area, a large concentration of gillnet fishery temporally overlaps periods of the most abundant occurrence of foraging diving birds. The aim of the article is to show how bycatch can impact the population of a diving duck. To assess this, we calculate the Potential Biological Removal (PBR) for the studied Greater Scaup population and we model the population change according to age-structured matrix models. Summing all the available recent figures on Greater Scaup bycatch in north-west Europe yields an estimated mean annual total of 3,991 individuals (2% of the flyway population). For a baseline stable population, an age-structured matrix model indicates that at this bycatch level the Greater Scaup population that winters in north-west Europe will decrease by 36% over the next 30 years, qualifying the status of the population as ‘Vulnerable’ according to IUCN criteria. As this population also experiences decline prior to bycatch, this decrease will be 57%, which qualifies the status as ‘Endangered’. PBR as an indicator of population vitality does not work in our case because the PBR-informed allowable bycatch values have a significantly negative impact on the population. Our results indicate unambiguously that fishery bycatch is among the most important threats responsible for the Greater Scaup’s decline. While recent data suggest that some improvement has taken place in the species’ status over the last 10 years, measures to protect Greater Scaup from bycatch are required. The solution should involve the prohibition of gillnet fishing in selected key sites and the use of mitigation techniques in other areas.

Understanding demographic processes over multiple spatial scales is vital for the optimization of conservation/management strategies, particularly for commercially harvested taxa such as the brown crab (Cancer pagurus L). Brown crab population genetic structure was investigated at (i) a local scale within the Irish Sea, which included comparisons with the Lundy No Take Zone (NTZ) and (ii) across the NE Atlantic. The results indicate that the brown crab does not exhibit strong spatial structure either within the Irish Sea or at the regional level, suggesting high gene flow within and among the Irish Sea, English Channel and North Sea. Comparisons between the Lundy NTZ and harvested areas revealed similarly high levels of genetic diversity. An intriguing result was that the Lundy NTZ sample exhibited a degree of genetic patchiness (ephemeral geographically unpatterned differentiation) which may indicate elevated recruitment skews within the NTZ. Overall, the results support the view that brown crabs within the sampled area belong to a single genetically panmictic stock and that if breeding stock sizes are maintained genetic drift will not be strong enough to reduce neutral genetic diversity. The highly connected nature of this species requires international cooperation for sustainable management, an important component of which will be the application of more powerful population genomic approaches to assess finer scale aspects of stock structure as well drivers of genetic patchiness reported for the species. This is a timely consideration in light of potential future misalignments between biological and geopolitical stock boundaries in the Irish Sea following Brexit.

The Istanbul Strait is an important cetacean habitat that is intensely used by humans. Yet little is known about their spatial-temporal distribution. To understand the encounter rates and residency patterns of bottlenose dolphins, photo-identification data were collected between 2011 and 2016 in the Istanbul Strait. The study showed that bottlenose dolphins are a regular, year-round component of the strait. The encounter rate was estimated to be four groups (22 individuals) per 10 km. The adjacent waters of Marmara Sea and Black Sea, that host relatively less marine traffic, had the highest number of encounters in the area. Conversely, the middle sections had the lowest number of encounters but the highest marine vessel density. Further, the encounter rates dropped to zero in the fishing zones, where the number of purse seines reached up to 100 per day. Additionally, dolphins showed varying degrees of residency patterns, with multi-year re-sightings. Maximum re-sighting distance was up to 35 km, which is more than the total length of the strait. This movement pattern should be investigated as it might reveal possible migration between local populations. This study finds that the Istanbul Strait serves as a critical habitat for the regional bottlenose dolphin populations and they are likely to be a part of a resident local population with a home range extending the length of the strait. Dedicated surveys with inter-regional collaborations are needed to evaluate the home range and population status of this endangered species for their effective conservation in one of the busiest waterways of the world.

Pleuroncodes monodon, an important fishery resource and key species in the Humboldt Current Large Marine ecosystem, has a prolonged reproductive period from winter until end of summer, and during this time females incubating their embryos are exposed to seasonal variation in food availability and in temperature. Additionally, in order to ensure successful reproduction and survival of embryos, changes occur in the main internal reserves and/or sources of energy of P. monodon. The aim of this study was to determine the extent of seasonal variation (winter vs summer) in the lipid content and fatty acid composition of ovigerous females and their embryos. The results show that a higher percentage of saturated and polyunsaturated fatty acids are found in females in winter. Similarly, the composition of fatty acids in embryos found here indicates that winter embryos have more saturated fatty acids and essential fatty acids (C18:2n6cis, C18:3n6 and C22:6n3) than do summer embryos. According to PCA analysis of fatty acid profile, samples from summer may be distinguished into two isolated groups with conspicuous variations in fatty acids profile of embryo and hepatopancreas. While in winter, the opposite pattern occurs in the fatty acid profile of embryo and hepatopancreas. These variations may be related to relevant physiological processes (reproduction and growth) and of their ontogeny (development and survival of offspring). Seasonal variation in the lipid content and composition of fatty acids of P. monodon could directly impact this species’ reproduction and survival and subsequently could have consequences on the food web and fishery exploitation.

Octopus mimus is the main octopus targeted by the small-scale fishery in the Eastern Pacific. Commercial catches of octopus from the Reserva de Producción Faunística Marino-Costera Puntilla de Santa Elena (REMACOPSE) Marine Protected Area in Ecuador were sampled from July to December 2013 in order to describe the reproduction and population structure of this octopus. The 4171 sampled octopuses ranged from 56 to 250 mm in mantle length (ML) and 45 to 3178 g in body weight (BW). Mean octopus weight did not change monthly. Males were mostly mature while the majority of females were immature. Presence of some mature and a few spent females in all months sampled suggests that the population shows an extended spawning period. No spawning peak could be properly defined. Sex ratios did not significantly shift from the expected 1:1 in most samples. Females mature at a larger size (1234 g, BW; 165 mm, ML) than males (487 g BW; 114 mm ML). We recommend considering a minimum legal size of 1200 g BW. A year-long sampling programme for O. mimus should also be completed in order to detect any spawning peak.

High plasticity in cephalopod populations shows dramatic changes in their biological traits. Commercial catches of Mayan octopus (Octopus maya) in six localities of the state of Campeche, Mexico, were sampled monthly for five consecutive fishing seasons (2005–2009) in order to describe variations in population structure and maturation. Octopus maya grows and matures during the fishing season, from August to December. Spent individuals predominate in January and February, revealing a year-long life cycle. However, the presence of a few spent females in all months sampled suggests that a small part of the population shows an extended spawning period. Overall sex ratios did not significantly shift from the expected 1:1 in most samples. Males are mostly mature while the majority of females are immature during the season. Use of illegal fishing gears (spear diving or pots) in central localities accounts for a larger share in mature females. Octopus size showed large interannual and geographic differences. Females mature at a larger size (1024 g body weight, BW; 124 mm mantle length, ML) than males (484 g BW; 91 mm ML). Size at maturity in both sexes varies more between seasons than between localities. Female ML at maturity is larger than the current minimum legal size and implications for current octopus fishing regulations are discussed.

Mangrove ecosystems are unique fish habitats because they provide shelter and food for juvenile fish. Hara Biosphere Reserve (HBR) is a coastal region in the Khuran Strait situated in the northern part of the Persian Gulf. Mangrove forests of this region are important for people's livelihoods. Moreover, shallow water, coastal wetlands and other estuarine habitats with very restricted water flow and nutrient rich areas provide shelter to young fish. The results of monitoring and Evaluation for Fishing Communities in 2008 showed that there are a total of 43 families of fish that were associated with HBR. Among 44 families Leiognathidae, Clupeidae, Carangidae and Mugilidae families are the most abundant fish species in the area. However, most popular fish were in the juvenile stage of their life cycle. Because of the rich diversity of fish in coastal waters, the lives of a large proportion of people living in this region are directly dependent on fishing. Results have shown that although there is no considerable difference in fish diversity among the different fishing methods, a clear distinction between the fishing methods and the weight of fish is obvious.

In Tunisia, elasmobranch landings have decreased substantially in recent years. Generally, species-specific information is largely unavailable for artisanal fisheries, but it is essential to increase knowledge and to ensure proper management of these species. This study analysed elasmobranch catches with longline fishery in the Gulf of Gabès. In total, 21 and 20 pelagic and bottom longline fishing trips were conducted, respectively, from July to September in 2007 and 2008. A total of eight elasmobranch species were caught: four batoids and four sharks. Pelagic longline captures were hooked externally while a high number of individuals captured with bottom longline were hooked internally. Discards due essentially to low commercial value and size represented 7.6% of total number of elasmobranch specimens caught. Longline landings in the Gulf of Gabès were principally composed of sandbar shark, Carcharhinus plumbeus, representing, respectively, 94.14% and 21.17% in number of pelagic and bottom longline captures. The importance of rhinobatids and Mustelus capture with bottom longline reflect their abundance in this area compared to other Mediterranean zones. Juveniles, including neonates with umbilical scars, dominated carcharhnids specimens, while smoothhound and guitarfish captures were dominated by mature individuals. Mitigation measures based on gear modifications, size limits and delineated nursery areas in the Gulf of Gabès should be developed to protect these vulnerable species.

The pink shrimp (Farfantepenaeus paulensis) is a very important fishery resource in southern/south Brazil. A great part of the total capture at these regions results from the artisanal fishery activity in Patos Lagoon estuary. The study of this species has importance because it is the main source of income for the communities of artisanal fisheries. This paper relates the climatic effects and the size of the species' adult stock with the harvest of pink shrimp in the estuary, in order to determine the influence of these variables on annual landings (t).

The reproductive systems of 39 male and 54 female Bathyraja albomaculata were assessed microscopically and compared with macroscopic maturity index values assigned by scientific observers. Inconsistencies were limited to ‘developing’ maturity stages in both sexes, but such discrepancies were attributed to different factors depending on sex. Furthermore, while spermatozoa were observed in the oviducal gland of females, they do not appear to accommodate long-term sperm storage in this species.

The wedge sole (Dicologoglossa cuneata, Moreau 1881) is a commercially important species for the artisanal fleet operating off the south-western Iberian Peninsula. During 2004 and 2005 a study was undertaken aiming to provide a scientific basis for management. Data collection included information on aspects of the fishery, spawning season, size at first maturity, tangle and gill-net selectivity. Seven nominal mesh sizes were used (40, 45 and 50 mm tangle nets and 40, 50, 60 and 70 mm gill-nets). Spawning lasts from December to June, with peaks in March and May. Length at first maturity for females was estimated at 18.5 cm. Catch rates decreased sharply with increasing mesh size, with tangle nets providing the highest yields. The log-normal selectivity model provided the best fit for specimens that were wedged. The higher catch-per-unit-effort of the smaller mesh sizes and the modal length of the fitted selectivity curve being below the size-at-maturity for wedge sole, suggests that the 50 mm nominal mesh size tangle net is the most appropriate for ensuring the fishery sustainability. Nevertheless, the minimum legal size should increase to at least 18 cm and a time–area closure should be implemented off the Guadiana River mouth.

This study uses a novel method for discriminating cohorts and investigating the population dynamics of the parasitic crustacean, Argulus foliaceus. Analysis of parasite length-frequency data was carried out in order to elucidate the timings and drivers behind the parasite's life cycle. Up to 6 cohorts of the parasite emerge through the course of 1 year in still-water trout fisheries in England. Recruitment ceases over the winter months; however, 3 cohorts of the parasite over-winter, 2 as eggs and 1 as a hatched stage. The technique, when used in conjunction with temperature data, also allowed for the reliable prediction of growth rates and provided estimates of egg incubation times and the length of hatching periods. These data showed that growth rates increased exponentially between the observed temperatures of 4 to 22°C. The method allowed for the time taken from hatching to egg laying under field conditions to be predicted and produced estimates that were validated against independent laboratory studies on the growth of the parasite.

Conflict between dolphins and fisheries is an important management issue in many parts of the world. In 2002, we examined the extent of depredation in the Italian small scale fishery by means of in situ interviews. Overall, 245 landing sites were investigated, representing 11.09% of the whole Italian artisanal fleet. The association between the commonly used artisanal fishing gear and the interacting fauna was investigated by means of correspondence analysis. Set gillnet and trammel nets were the types of the fishing gear most vulnerable to dolphin depredation; the interaction with these gear amounted to 66.4% while fish damage was reported in 72.2% of the cases. A regional ranking of the interactions in terms of both fishing gear alteration and fish damage, shows that the problem is most pressing in the Friuli, Campania, Sardinia and Apulia regions. This study is the first attempt to monitor dolphin–fisheries interactions and assess depredation rates in Italy, providing information on the areas where future investigation should be concentrated.

During a monitoring programme of stranded marine mammals conducted along the north-east coast of the Rio de Janeiro State, Brazil, we collected marine tucuxi dolphins (Sotalia guianensis) stranded along the beach. We examined the carcasses to identify characteristic evidences of fishery by-catch. From July 2001 to August 2007 43 S. guianensis were found in the study area, with an annual mean of 6.1 stranding events. Dolphins stranded with evidence of fishery interaction (‘by-catch’) occurred in almost every year (annual mean = 2). The majority of the by-catch events occurred during winter and spring. Most of the stranded dolphins were sexually mature. From 43 S. guianensis stranded from 2001 to 2007, 32.5% (N = 14) of these presented evidence of by-catch. Twenty-nine other dolphins did not show clear evidence of by-catch or it could not be evaluated. Most of the by-caught dolphins occurred in the northern zones of the study area where gill-net use is intense.

The population and conservation status of crocodiles throughout West and Central Africa is poorly known and the IUCN Crocodile Specialist Group's highest priority recommendations are country status surveys and examination of potential threats. This study presents survey data and a review of the conservation status of the Nile crocodile Crocodylus niloticus, slender-snouted crocodile Mecistops cataphractus and African dwarf crocodile Osteolaemus tetraspis at 67 sites throughout Ghana and Côte d'Ivoire. No crocodiles were sighted in 31.5% of surveys but, where encountered, densities averaged 0.90 crocodiles sighted km-1. The most frequently encountered crocodile was C. niloticus (94% of sightings) with population structure highly biased to individuals < 1 year of age (41.4%). Only 14 M. cataphractus were observed. Local informants report that crocodiles were more common 10–20 years ago than at present. There is now little commercial harvest, which includes limited use in the bushmeat and traditional medicine markets, because of the crocodile's scarcity. Habitat encroachment and incidental bycatch in fishing devices appear to be the major threats. Actions needed to improve the conservation status of crocodile populations in both countries, and throughout the region, are discussed.

The East China Sea (ECS) supports a highly productive fishery and is rich in biodiversity, but economic development in China and peripheral countries has led to intensifying anthropogenic impacts in the ECS. In response to this the Chinese government has introduced a range of marine spatial management measures. A spatial ecosystem model (Ecospace) of the ECS was developed to examine (1) the likely nature of trade-offs between fishery and conservation goals resulting from the marine protected areas (MPAs) and (2) possible trade-offs within the fishery sector resulting from the MPAs. The results suggest that overall the fishery has benefited from all of the simulated MPAs, whereas, although they defy categorical interpretation, effects of the MPAs on biodiversity and ecosystem structure are variable. Simultaneous application of several metrics of ecosystem status indicates that the perceived effect of an MPA on ecosystem status can depend on which metrics for ecosystem status are used, and how these metrics are interpreted. The simulations indicate that a fisheries and conservation outcome beneficial to all is possible, but not guaranteed, with the creation of an MPA. Total landings and profitability are predicted to have increased as a result of each of the MPAs, albeit at the cost of reduced landings and profits to some sectors of the fishery. This study demonstrates the benefits of the additional information relating to biodiversity, ecosystem structure and within fishery dynamics available from spatial ecosystem models compared to the single species models typically used to examine MPA effects. However, the use of a more complex ecosystem model introduces additional uncertainty in model interpretation.

The marine turtle fishery of Grenada was assessed using interviews with marine turtle fishermen and by examination of turtle catch data from a major landing site. An estimated 782 turtles, mainly Endangered green turtles Chelonia mydas and Critically Endangered hawksbill turtles Eretmochelys imbricata, were caught around Grenada and its sister island Carriacou each year between 1996 and 2001 during an annual 8-month open season, with only a small percentage being officially recorded at a landing site. Turtles were primarily caught with nets and spearguns, with more green turtles caught by net fishermen and more hawksbill turtles by spear fishermen. Catch per unit effort data suggested that relative abundance had declined since the previous estimate was made in 1969. Few adult green or loggerhead turtles Caretta caretta were caught, indicating the relative scarcity of this size class of these two species around Grenada. Adult-sized hawksbill turtles were caught regularly, with larger adults being caught in the non-breeding months of the open season than in the breeding months. A higher percentage of adult hawksbill turtles present during the breeding season are likely to be animals that nest in Grenada, and their smaller size may result from historically heavy fishing pressure. The larger sized adults caught during the non-breeding season are likely to be animals that forage around Grenada but breed elsewhere in the Caribbean where they are protected.

A preliminary economic evaluation of the feasibility of establishing a fishery to process red crab meal (Pleuroncodes planipes) was conducted. Risk assessment indicated that a fishery of nine boats could operate with an average 1.53 benefit-cost ratio (B C−1) and annual net revenues (NR) of US$427 840, and that there is certainty of obtaining economic profit in every season, with a B C−1 > 1 and NR > 0. Total catch and average catch per trip could be reduced from a total baseline catch of 10 328 tons (1735 t meal) to 6061 (1844 t meal), and from a baseline catch per trip of 11.4 t (4.78 t meal) to 6.73 tons (4.85 t meal) without economic losses. There was no possibility for profit when total catch and average catch per trip were, respectively, lower than 5365 t (1648 t meal) and 5.96 t (4.71 t meal). For a single-fishing trip operation, average B C−1 was 1.5 and NR was US$480. We determined that there was a confidence level of 84% to generate profits. To guarantee profits, a catch of 13.5 t per trip (1.35 t meal) should be obtained. Single trips catching less than 3.3 t (0.94 t meal) cannot make a profit. Sensitivity analysis indicated that plant processing efficiency for converting fresh red crab to meal, catch per trip, and sales price of red crab meal were most important in determining B C−1 and NR values. Plant efficiency constitutes the main element that needs to be optimized, particularly management practices to preserve fresh catch quality. A low sensitivity to costs for processing suggests the possibility of negotiating a higher price and the opportunity for processing plants to venture into processing of red crab meal.

This paper explores effects of environmental variability on the life cycle of the chokka squid, Loligo vulgaris reynaudii in South Africa, particularly the effect of physical and chemical influences on adult distribution, and the availability of spawning aggregations to the local jig fishery. The following hypotheses are presented: 1) temperature, dissolved oxygen and currents have a direct effect on the demersal distribution of adult chokka on the feeding grounds, but this is restricted to the west coast where environmental conditions are more extreme relative to the south coast, 2) chokka catches increase in proportion to the extent of coastal upwelling, 3) spawning behavior along the inshore regions (<50m) is strongly influenced by turbidity near the seabed. High turbidity forces the spawning popuation to lay their eggs in deeper waters, and are thus not available to the jig fishery. 4) El Niño – Southern Oscillation (ENSO) events are linked with large fluctuations in the availability of spawning squid aggregations to the inshore jig fishery.