International trade in vulnerable marine species is regulated once they are listed in CITES Appendices (the Convention on International Trade in Endangered Species of Wild Fauna and Flora). Parties to the Convention submit proposal(s) 150 days prior to the CITES Conference for voting on the inclusion of new species in Appendices I and II, making a case for why CITES listing criteria are met in each case. Before the vote, Parties receive advice from (a) the Food and Agriculture Organization of the United Nations, (b) the International Union for Conservation of Nature-TRAFFIC and (c) the CITES Secretariat, among others. This paper offers an expert review of listing processes, which are the subject of much debate in fishery and environment-protection communities, looking at two specific cases: silky shark (Carcharhinus falciformis, Carcharhinidae) and bigeye thresher shark (Alopias superciliosus, Alopiidae). The reviewers determine that the evidence made available to voting Parties is substantial, but suffers from non-standard presentation across assessments. The best available data are not always presented or described transparently in relation to CITES criteria. An extension of the assessment period, as well as the opportunity to refute evidence, has been suggested as ways to support more informed and effective decision-making by CITES Parties, whose composition of delegations varies greatly in their experience of marine species management and trade. Experts welcomed a greater coherence of advice between fishery and non-fishery sources in the long term, and proposed a range of suggested improvements for the delivery of information and advice to CITES Parties.

Recent observational and numerical studies have suggested that the decadal modulation of the Kuroshio Extension system, driven by mesoscale eddies, profoundly affect the basin scale physical and biogeochemical oceanography. However, it remains unclear how these decadal changes affect distribution and abundance of fish species in this region. In this study, 26,964 swordfish catch data obtained by longliners during 2004–2010 in the western North Pacific are analyzed with an eddy-resolving ocean reanalysis by using mesoscale dynamic parameters and an eddy detection technique, to clarify the effects of mesoscale eddies and their variabilities on the swordfish relative abundance. During this period, the Kuroshio Extension underwent two different dynamic phases: stable path state in 2004, 2005, and 2010; and unstable path state during 2006–2009. Based on our analyses, we show here that swordfish are more concentrated in and near the anticyclonic warm-core eddies in the northern site, 36–45°N, of the Kuroshio Extension system, especially during the unstable path phase. This is found to be caused by the interannual modulation of mesoscale eddy activities due to more warm-core rings generated from the unstable Kuroshio Extension, making it easier for fishermen to target swordfish in this region.

The age of striped marlin (Kajikia audax) in days and years (daily and yearly ages) were estimated by counts of otolith microincrements (n=25) and dorsal fin spine annuli (n=175) using specimens caught in the tropical eastern North Pacific between September and November 2004. Daily ages of small striped marlin (87.0–145.5cm lower jaw–fork length) were estimated to range from 81 to 239 days, which indicates that the species in the area grow, on average, to over 100cm within 4 months. Back-calculated hatch dates were estimated to be from March to July; this period is earlier than the known spawning season in a slightly more northern area. Approximately 20% of these year-0 striped marlin had one or more growth bands in the sectioned spine. They were thought to be false annual growth bands and excluded from yearly age estimation. The estimated yearly age of 175 individuals (87.0–228.4cm) ranged from 0 to 5 and was dominated by ages-0 to 3 (>90%). Age composition was different among three subregions in the eastern North Pacific.

We analyzed the factor affecting bycatch occurrence rate. Random forest was applied to analyze. We constructed four models examining effect of species group, season, year, environmental factors, distance from the colonies, a lunar phase, and catch of fish. Our model was likely to be a statistically appropriate model because out of bags is an acceptable range though a little high. Dominant variables in common with analyzed four models were latitude, longitude, elapsed days from the first day of the year, number of observed hooks, species group, sea surface temperature in this study. Also year, cruise ID and lunar phase were dominant variables in common with two to three models. Those variables would have the large impact on bycatch occurrence rate. Thus, it was suggested that those variables should be considered in the comparison between CPCs and in the collaboration work.

Population growth rate, which depends on several biological parameters, is valuable information for the conservation and management of pelagic sharks, such as blue and shortfin mako sharks. However, reported biological parameters for estimating the population growth rates of these sharks differ by sex and display large variability. To estimate the appropriate population growth rate and clarify relationships between growth rate and relevant biological parameters, we developed a two-sex age-structured matrix population model and estimated the population growth rate using combinations of biological parameters. We addressed elasticity analysis and clarified the population growth rate sensitivity. For the blue shark, the estimated median population growth rate was 0.384 with a range of minimum and maximum values of 0.195-0.533, whereas those values of the shortfin mako shark were 0.102 and 0.007-0.318, respectively. The maturity age of male sharks had the largest impact for blue sharks, whereas that of female sharks had the largest impact for shortfin mako sharks. Hypotheses for the survival process of sharks also had a large impact on the population growth rate estimation. Both shark maturity age and survival rate were based on ageing validation data, indicating the importance of validating the quality of these data for the conservation and management of large pelagic sharks.

The blue shark (Prionace glauca) is the most frequently captured shark in pelagic oceanic fisheries, especially pelagic longlines targeting swordfish and/or tunas. As part of cooperative scientific efforts for fisheries and biological data collection, information from fishery observers, scientific projects and surveys, and from recreational fisheries from several nations in the Atlantic and Indian Oceans was compiled. Data sets included information on location, size and sex, in a total of 478,220 blue shark records collected between 1966 and 2014. Sizes ranged from 36 to 394cm fork length. Considerable variability was observed in the size distribution by region and season in both oceans. Larger blue sharks tend to occur in equatorial and tropical regions, and smaller specimens in higher latitudes in temperate waters. Differences in sex ratios were also detected spatially and seasonally. Nursery areas in the Atlantic seem to occur in the temperate south-east off South Africa and Namibia, in the south-west off southern Brazil and Uruguay, and in the north-east off the Iberian Peninsula and the Azores. Parturition may occur in the tropical north-east off West Africa. In the Indian Ocean, nursery areas also seem to occur in temperate waters, especially in the south-west Indian Ocean off South Africa, and in the south-east off south-western Australia. The distributional patterns presented in this study provide a better understanding of how blue sharks segregate by size and sex, spatially and temporally, and improve the scientific advice to help adopt more informed and efficient management and conservation measures for this cosmopolitan species.

The Kuroshio–Oyashio transition zone is one of the most important fishing grounds for pelagic fish, including blue shark and swordfish, which are primarily targeted by shallower Japanese longliners. We evaluated the fishing behavior of Japanese longliners based at the Kesennuma fishing port to estimate the standardized catch per unit of effort (CPUE) of blue shark. In our analysis, we first used data that had been filtered for blue shark sets and found that annual target shifts occurred seasonally and geographically; the greatest change in target species, from swordfish to blue shark, occurred in spring (April–June). Beginning in the early 1990s, the fishing grounds shifted from the southwest to the northeast of the North Pacific, and the number of sets targeting blue shark gradually increased. To incorporate this variable target behavior into the abundance index, the 10th percentile of the swordfish CPUE values was applied as the target indicator in the CPUE standardization model. The results indicate an upward population trend that has been caused by a decrease in fishing pressure from the early 1990s due to the prohibition of drift nets in 1992 and the subsequent decrease in longline vessels.

Longline surveys have been conducted in the Northwest Pacific Ocean from 2000 to 2014 using chartered commercial longline vessels. Each year, two cruises were conducted offshore of northeastern Japan from mid-April to mid-June. For each longline set during the surveys, onboard scientists collected detailed biological information about the species caught, such as the size and sex, and recorded the catch numbers for all species. Blue shark (Prionace glauca) and shortfin mako (Isurus oxyrinchus) have eurythermal distributions, but the application of a generalized additive model (GAM) showed that the sea surface temperatures (SSTs) at catch sites positive for shortfin mako were warmer than those for blue shark. On the basis of the GAM, the probabilities of occurrence of both sharks differed by size category: small sharks had a narrower SST range than that of large sharks. Most catches of both sharks were juveniles, and the nominal catch rate of blue shark was more than 10 times that of shortfin mako. The standardized catch per unit effort (CPUE) for both species was calculated using a generalized linear model (GLM) with negative binomial errors, or a delta-lognormal GLM. The standardized CPUE for blue shark in the second quarter of the year peaked in the mid-2000s and then decreased, but it has been increasing since 2012. The CPUE for shortfin mako in the second quarter generally increased, with fluctuations.

The bigeye thresher ( Alopias supercilious ) is occasionally caught as bycatch in pelagic longline fisheries targeting tunas and swordfish. Still, it is one of the least known and studied of all pelagic sharks, which hinders assessment of the status of its populations. As part of an ongoing cooperative program for fisheries and biological data collection, information collected by fishery observers and through scientific projects from several nations that undertake fishing activities in the Atlantic (Japan, Portugal, Spain, Taiwan, Uruguay and US) was compiled and analyzed. Datasets include information on location, size, sex and, in some cases, maturity stage. A total of 5590 bigeye thresher records collected between 1992 and 2013 were compiled, with sizes ranging from 70 to 305 cm fork length (FL). Considerable variability was observed in size, with tropical regions recording a smaller mean size compared to other regions. The distribution of juvenile and adult specimens also showed considerable variability, and the sex ratios varied between regions and size classes. Median sizes at maturity were estimated at 208.6 cm FL for females and 159.2 cm FL for males. Pregnant females were recorded in the tropical northeast and southwest Atlantic, with these regions possibly serving as nursery areas. The biological and distributional patterns presented in this study provide a better understanding of different aspects of this species in the Atlantic, which can help managers adopt more informed and efficient conservation measures.

The new seabird mitigation regulation was enforced in July 2014 in the area south of 25S in IOTC convention area. It demand for fisheries to adopt two of three mitigation measures of tori-line, night setting and blanch line weighting which have high effectiveness for mitigation of seabird bycatch (Melvin et al. 2014, Sato et al. 2014). In this document, Japanese seabird by catch data in the south Indian Ocean (south of 25S) collected by on-board observers in the period before and after the introduction of the new regulation were reviewed, to explore the possibility to evaluate the effectiveness of the new mitigation measures. It seems that the distribution of the observer data collected form almost main fishing areas of Japanese longliners in the period analyzed. The observer data indicated that many Japanese tuna longline vessel (71-94%) had already adopted the combination use of weighting blanch line and Tori line or night setting and Tori line before the introduction of regulation (2012 2013). This would be mostly due to the fact that bait loss by seabirds is one of serious concern of Japanese fishers but also suggest their positive attitude toward seabird conservation. The amount of data seemed insufficient as data after the introduction of the new regulation was only one year, analytical method supposed to be rather preliminary. However, the good efficiency of the regulation with using fisheries data, further collection of data appeared to be necessary for the stochastic evaluation of the effect of new mitigation measure, such as considering the effect of the interaction of each mitigation, target species. Also, the detail situation when the mitigation measures were used would be needed to investigate in the future. Introduction Recently, new seabird mitigation regulation was introduced in ICCAT, IOTC and WCPFC conventional area (ICCAT; Rec11-09 started from July 2013,IOTC; Res 12/06 started from July 2014, WCPFC; Conservation Measure 2012-07 started from July 2014), and the commission of these tuna RFMOs tasked their scientific committee to evaluate its effectiveness of the regulation needs to be tested. It demand for fisheries to adopt two of three mitigation measures of tori-line, night setting and blanch line weighting which have high effectiveness for mitigation of seabird bycatch (Melvin et al. 2014, Sato et al. 2014). In this document, Japanese seabird by catch data in the south Indian Ocean (south of 25S) collected by on-board observers in the period before and after the introduction of the new regulation were reviewed, to explore the possibility to evaluate the effectiveness of the new mitigation measures. It seems that the distribution of the observer data collected form almost main fishing areas of Japanese longliners in the period analyzed. IOTC–2015–WPEB11–37 Rev_1

Age determination and growth estimation of blue marlin (Makaira nigricans) were performed by combining method of otolith micro-increment counts of 27 young (17–185-cm lower jaw–fork length, LJFL) and sectioned dorsal fin spines of 571 adult individuals (155–352cm). Otolith micro-increments were counted with ages of 26–338 days old. The estimated mean length (185cm) at Year 1 and growth rate were used to predict the position of the first annual growth band in sectioned fin spines. Distinct growth bands were formed in fin spines annually between September and October. Indistinct growth bands were considered false-annual growth bands. The observed and back-calculated LJFLs at each age were highly variable for both sexes. Von Bertalanffy growth parameters were estimated using mean back-calculated LJFL data as: L∞=295cm, k=0.23, t0=–3.31 years for females and 212cm, 0.29, –4.49 years for males. Females grew to >200cm in 2 years and to >250cm in 5 years on average, whereas the growth of males slowed appreciably after they reached the age of 1 year. This is the first study of blue marlin growth for entire life stages.

Cosmopolitan pelagic species often show shallow genetic divergence and weak, or no, genetic structure across a species’ range. However, there have been few such genetic studies for pelagic sharks. The pelagic blue shark (Prionace glauca) has a broad circumglobal distribution in tropical and temperate oceans. To investigate the population genetic structure and demographic history of this species, we analysed variation in the mitochondrial cytochrome b sequence for a total of 404 specimens collected from 10 locations across the Indo-Pacific region. The observed genetic diversities were comparable among sampling locations (h=0.77–0.87; π=0.17–0.23%). Spatial analysis of molecular variance (SAMOVA), pairwise ΦST and conventional FST estimates, and analysis of isolation with migration indicated weak or no genetic differentiation of this species across the Indo-Pacific region. The results of three phylogeographic analyses (i.e. mismatch distribution and parsimony haplotype network analyses and a neutrality test) suggested that the Pacific blue shark had historically experienced a sudden population expansion. These results, coupled with the biological properties of this species, imply that historical climate fluctuation has had only a minor effect on the genetic structuring of the blue shark.

The North Pacific Transition Zone (NPTZ) is one of the most productive offshore regions. To identify important habitats for pelagic top predators within this region, we investigated the at-sea distributions of black-footed (Phoebastria nigripes) and Laysan albatrosses (P. immutabilis) by vessel-based surveys during their non-breeding season (July and October in 2010 and September and October in 2011). We developed statistical models using satellite-based oceanographic data at spatial scales of 4, 20 and 80 km to explain their densities. For both species, sea surface temperatures (SST) and distance to the Emperor Seamounts emerged as important factors in the better-fitting models at all spatial scales. In addition, black-footed albatrosses were widely distributed in the NPTZ (SST 17.7–27.4 °C), whereas Laysan albatrosses favoured northern and colder waters (13.6–25.4 °C). Our results also indicated that the Emperor Seamounts, where trawling and longline fishing occur, were an important habitat for both species in the NPTZ. Therefore, careful attention should be paid to interactions between fisheries and albatross species in this region.

This study used a delta-lognormal model to analyze monthly catches of age-0 Pacific bluefin tuna by the troll fishery. The model included fixed effects of month, area, and month–area interaction, and random effects of port, year and port–year interaction. The catch patterns by month and area predicted by the statistical model (standardized catch) revealed that main fishing grounds along the Tsushima Warm Current generally shifted from north to south as the season turned from autumn to winter. In contrast, the standardized catch along the Kuroshio Current did not show such clear spatiotemporal patterns. The standardized catch along the Tsushima Warm Current is significantly associated with average monthly sea surface temperatures in the fishing grounds and consistent with migration routes revealed by tagging experiments in previous studies. These associations indicate the spatiotemporal catch pattern in the Tsushima Warm Current region partly reflects seasonal migration. Knowledge of the possible associations among fish migration, environmental factors and spatiotemporal distribution of the catch will contribute to future management of this species.

To examine the effectiveness of the paired tori lines (PT) for reducing seabird bycatch in pelagic longline fisheries, bait attack behaviors during PT deployment was compared with that during single tori line (ST) deployment. Detailed observations of seabird species abundance and attacks on baits were conducted from a longliner operating in the western North Pacific from December 2010 to January 2011. Line settings alternated between ST and PT deployments. About 90% of the seabirds attending the vessel were Laysan albatrosses (Phoebastria immutabilis), and most attacks were by this species. Attacks occurred across broad areas from 25 to 200 m of the stern during ST deployments, whereas PT deployment resulted in few attacks within 75 m of the stern. The number of secondary attacks (birds charging for the bait brought to the surface by the bird making the primary attack) was significantly lower during PT than during ST deployment. These results suggest that PT performed better than ST in reducing bait attacks, and consequently seabird mortality. (C) 2012 Elsevier B.V. All rights reserved.

The number and weight of shortfin mako caught by the Japanese tuna longline vessels in the Atlantic was estimated based on the logbook data and the standardized CPUE from 1994 to 2010. Live releases and dead discards were estimated based on the information on the life status which was collected in the observer program. The catch number was estimated at 1,9164,395 t for the North (from the equator to South of 50 degrees North) and 665-6,720 t for the South, and the catch weight was estimated at 72-227 t for the North and 32-308 t for South.

Knowledge of a species’ distribution is an important element in its effective management and conservation. The porbeagle (Lamna nasus) is a common by-catch shark in the tuna longline fishery in the southern hemisphere, but its distribution and abundance are largely unknown. The investigation of observer data from the tuna longline fishery and other fishery survey data has revealed that (1) porbeagles are distributed in the pelagic waters across the oceans of the southern hemisphere, (2) juveniles and adults are distributed in cooler environments than are neonates, (3) pregnant females occur in the pelagic waters of the Indian Ocean and the Tasman Sea, most being frequently recorded around the Cape of Good Hope between June and July and (4) the standardised catch per unit effort (CPUE) based on tuna longline fishery (1994–2011) and driftnet survey (1982–1990) data indicate no continuous decreasing trend in the abundance of the southern porbeagle, contrary to the declining trend reported in a limited region in the South Atlantic. Considering its circumglobal distribution, stock status of this population should be assessed using information from the areas of its major distribution, including pelagic waters, and international coordination across oceans is necessary for the effective management of this population.