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This study identifies differences in vessel efficiency amongst purse seiners in Vietnamese fishery. Deterministic data envelopment analysis (DEA) was used to assess relative capacity utilisation of each vessel, and double bootstrap DEA was adopted to overcome some of the drawbacks of nonparametric DEA. The study was based on a survey of costs and earnings from 52 purse seiners in 2016, revealing an average vessel profit margin of 11%. By adopting double bootstrap DEA while assuming variable returns to scale, mean capacity utilisation was found to be 0.72 (with 95% confidence interval from 0.67 to 0.79). This indicates that to sustain the current catch levels, expected inputs should be reduced by 21-33%. The study shows that vessel size, fishing experience, and family size of skippers, all are factors affecting the capacity utilisation. [ABSTRACT FROM AUTHOR]

Fishing activities are important for food resources and economics globally, with more than 120 million people depending on fishing for their livelihood. Fisheries management, and the related crackdown on illegal fishing has been rapidly evolving in the last several years, particularly in Indonesian waters. This is critically important because of the significant fisheries resources within the region (estimated at more than $2 billion USD per year). The changes in regulations, including a moratorium on foreign vessels and on transhipment by foreign vessels, as well as changes in legislation related to domestic vessel activities means that Indonesia is in the limelight on addressing illegal, unreported and unregulated (IUU) fishing activities. An expert group identified key behaviours by vessel operators that indicate violations of these regulations, in particular the regulations on foreign and domestic transhipment. In this paper the transhipment indicators in purse seine and long line vessels developed in the workshop are characterised, governance changes are discussed, and the perverse consequences and impacts of new policies that have recently been implemented are highlighted. [ABSTRACT FROM AUTHOR]

Background. Purse seining with the use of light is among the most common fishing practices around the world, but there is lack of studies on the effect of light on the feeding of the target species in this kind of fishery and the possible consequences for other prey species. The presently reported investigation intended to provide indications on this issue by studying the diet of Atherina boyeri Risso, 1810, which is the target species of professional purse seine fishery, conducted using light in Lake Trichonis (Greece), and by comparing the acquired results with those of previous studies where the samples were taken without using light. Materials and methods. A seven-month (June through December 2014) purse seining fishing was conducted at night around two lamp rafts: 1) a traditional lamp raft producing white LED light and 2) an autonomous photovoltaic-battery-LED lamp raft producing green LED light. Stomach content analysis was conducted on 100 randomly selected specimens from each sample and the relative prey abundance and frequency of occurrence for each prey category was estimated. Calculations of predation pressure of A. boyeri upon the fish larvae of a goby, Economidichthys trichonis Economidis et Miller, 1990, were performed. Results. The study revealed the intense effect of light on the attraction and capture of prey species rarely found in previous studies, such as the larvae of the native and endangered fish E. trichonis, amphipods, and copepod nauplii. No significant differences were observed between the two light colours. A preference shift to larger prey with the increase of ontogenetic stage of A. boyeri was observed. Several thousands of pre-recruited E. trichonis larvae may be preyed upon each night around a single lamp especially during summer. Conclusion. Fishing with light may alter the dietary preference of the target fish species and even of the entire fish community. This may have serious consequences on the younger ontogenetic stages of other fish populations, especially when it coincides with their reproductive period. Considering the lack of similar field studies, the present results may stimulate analogous investigations on the effects of fishing lights in other marine and freshwater ecosystems worldwide. [ABSTRACT FROM AUTHOR]

By focusing on a single species and multiple fisheries, this study provides a stock assessment of the Spanish mackerel caught mostly by Korean large trawl (LT), large purse seine (LPS), and large pair trawl (LPT) fisheries. We standardize the fishing efforts for the three fisheries by using a general linear model. We also employ a surplus production model, the Clarke-Yoshimoto-Pooley (CYP) model, based on the Gompertz growth function. The CYP model estimates the maximum sustainable yield, allowable biological catch (ABC), and associated fishing efforts, while a bioeconomic model is used to estimate the maximum economic yield and associated fishing efforts. Furthermore, the study analyzes the economic interactions among the LT, LPS, and LPT fisheries in the Republic of Korea. The economic analysis compares the net profits of the three different axes accruing to the three fisheries from the estimated ABC. The results show that fishing efforts to catch Spanish mackerel have recently risen in the seas of Korea; however, the stock has reduced because of overfishing. Thus, the study's findings suggest that total allowable catch management is necessary for single species and multiple fisheries in order to preserve the Spanish mackerel stock in Korea. [ABSTRACT FROM AUTHOR]

Tuna fisheries catch over three million tonnes of skipjack tuna (Katsuwonus pelamis) each year, the majority of which come from purse-seine vessels targeting fish associated with man-made fish aggregating devices (FADs). A significant challenge for fisheries management is to maximize the efficiency of skipjack tuna catches whilst minimizing the bycatch of small and immature bigeye (Thunnus obesus) and yellowfin (T. albacares) tuna, for which long-term sustainability is uncertain in 75% of the world’s stocks. To better manage the issues common with this fishing method, an improved understanding of tuna behaviour around FADs is necessary. We probabilistically classified the vertical behavioural patterns of 50 bigeye and 35 yellowfin tuna (mean fork length 72cm and 70cm, respectively) electronically tagged throughout the western and central Pacific Ocean into shallow and deep states, using a state-space modelling approach. The occurrence of surface-association behaviours, defined as an individual remaining in a shallow state for 24-hours, was examined in relation to known capture events and FAD density. In general, surface-association events for both species were short and lasted on average less than three days, although events as long as 28 days were observed, and were more common in yellowfin when in archipelagic waters. Events were longest immediately following tagging in 62% and 17% of bigeye and yellowfin, respectively. Surface-association behaviour was not generally estimated just prior to recapture, being either non-existent or shorter than two days for 85% of bigeye and 74% of yellowfin. Current management measures in purse-seine tuna fisheries involve periodic or spatial closures for FAD use. If the chief benefit to purse-seine fishers of surface-association around floating objects is in locating schools in horizontal space at short-term time-scales, rather than holding fish near the surface for extended periods, controlling the number of sets made on FADs should be explored further as an additional management tool. [ABSTRACT FROM AUTHOR]

The purse seine fleet in southeastern and southern Brazil has the Brazilian sardine Sardinella brasiliensis as the target species, and fishery management is based solely on its life cycle. This study aimed to analyze a possible overlap of the reproductive cycle and recruitment of the main species caught by seine fleet. During the daily program of industrial fishing monitoring in the ports of Itajaí and Navegantes (Santa Catarina) biometrics were performed twice a month at landings between 2000 and 2013 for posterior analysis in laboratory abroad. The samples analyzed did not include part of the reproductive period and the recruitment due to the closed seasons. The size at first maturity (L50) was obtained by adjusting the proportion of adult females to a logistic model. The reproductive period was determined by analyzing gonadosomatic index and proportion of the maturation stages. Recruitment was determined from the length distribution and the ratio of immature throughout the year. L50 determined was 18.60 cm for S. brasiliensis, 19.58 cm for Opisthonema oglinum, 18.48 cm for Chloroscombrus chrysurus and 21.22 cm for Scomber japonicus. The analyzed species overlapped spawning period between November and April and recruitment in June and July. In the case of directing fishing effort to these non-target species, the possibility of inclusion of these species in closed seasons of target species could ensure a better management and consequently the sustainability of this activity. [ABSTRACT FROM AUTHOR]

Portugal is the third highest per capita consumer of fish in the world, with a fishing fleet consisting of trawlers, purse-seiners and multi-gear vessels, which use a wide variety of fishing gears, such as gillnets, trammel nets, longlines or traps. Climate change affects ocean conditions, impacting marine organisms and ecosystems, with consequences for marine fisheries. The consequences of climate change on fishing communities will depend on their exposure to this factor, the sensitivity of target species and ecosystems to climate change and fishermen’s ability to adapt to climate change. The Portuguese coast is mainly north-south oriented and located in a biogeographic transition zone, between temperate and subtropical waters, where the northern or southern distribution limits of several species can be found. Also, the Portuguese coast is expected to suffer changes in temperature and precipitation more accelerated than the global mean alteration rate, which makes it particularly adequate for studies of the effect of climate change on coastal communities and fisheries. The present study analysed trends in landings of the most important fishing métiers in the Portuguese coast and the vulnerability and adaptation capacity of Portuguese fisheries to climate change. Official Portuguese landings (1992–2012) were analysed and a survey was conducted to assess fishermen’s perception of landings and their potential behaviour in response to the effects of climate change on fisheries. Eighteen new species were landed in Portuguese fisheries over the past 5 years, of which 12 were tropical or subtropical and 5 had their distribution limit along the Portuguese coast. A latitudinal pattern in the number of new species in landings was found, agreeing with a northward shift of subtropical species. The south coast has shown a higher vulnerability to climate change, in terms of both exposure and sensitivity of target species and ecosystems to its effects. Trawlermen may be more adaptable and less vulnerable to climate change, given the high mobility of their fleet. Multi-gear fisheries may be more flexible in changing target species or fishing gear, which makes them potentially less vulnerable to climate change. On the other hand, the high sensitivity of sardine to the effects of climate change makes the purse-seine fisheries particularly vulnerable to climate change. [ABSTRACT FROM AUTHOR]

Seabird bycatch in commercial fisheries has been a growing conservation concern over the past 25 years. Large-scale fisheries employing gears known to incidentally catch seabirds operate off eastern Canada, however, regional bycatch information is limited., Using data collected from 1998-2011 by observers onboard Canadian domestic and foreign vessels, fishery sectors and target fisheries taking seabirds were identified, as were the seabirds most frequently taken. In addition, maps of seabird bycatch rates were used to identify localized areas where catch rates were high., Seabird bycatch was widespread. Despite generally low observer coverage, > 5000 bird deaths were recorded; most observed mortalities occurred in gillnet and longline sectors during summer and autumn. While the overall magnitude of seabird bycatch has likely decreased substantially since closure of the Atlantic cod Gadus morhua and Atlantic salmon Salmo salar gillnet fisheries in 1992, localized areas with high bycatch rates persist., For example, in Baffin Bay and Davis Strait, bycatch rates of northern fulmars Fulmarus glacialis were high in gillnet and longline fisheries targeting Greenland halibut Reinhardtius hippoglossoides near breeding colonies. In offshore areas of the Grand Bank, catch rates of migrant shearwaters ( Puffinus and Calonectris spp.) were high in deep-set gillnet fisheries for Greenland halibut and monkfish Lophius americanus during summer. In inshore regions of eastern Newfoundland, gillnets set for Atlantic cod near breeding colonies resulted in high bycatch rates of murres Uria spp. and shearwaters during summer. High bycatch rates were also observed in pelagic longline fisheries along the Scotian Shelf., While the observer data have highlighted several localized areas with high bycatch rates, information for inshore gillnet fisheries, which take seabirds but are poorly covered by the observer programme, and regional information on fishing effort must both be considered for comprehensive assessment of seabird risk areas and consequent management needs in eastern Canada., Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The Ecosystem Approach to Fisheries Management claims that fisheries management should take into account the ecosystem processes; in that context, it is useful to examine the functional traits of fisheries assemblages. This can be a challenge in multispecies fisheries. We used 21 biological traits of 86 species to investigate the relationship between-species and trait composition and to identify species with rare functional traits. Combining these traits with two catch datasets from the eastern Mediterranean (Patraikos Gulf: small-scale fleet, eastern Ionian Sea: entire multispecies fleet), we investigated whether certain fishing tactics or gears tend to remove specific traits, using multivariate methodologies. Species and traits composition of the catches were related, but an important part of trait variability was not explained by species composition. Rare traits and trait combinations were found for important target or bycatch species. Differences in the traits composition of fishing operations were revealed both between fishing tactics (Patraikos) as well as gears and areas (eastern Ionian); hierarchical clustering and MDS indicated the distinction of purse-seine catches at gear level. SIMPER analysis by trait indicated associations of certain trait categories mainly with purse-seines (at gear level) and longline metiers and a trammel-net metier (at metier level). The identification of rare traits or their combinations can have significant management implications as overfishing of the species with these traits could result in altering assemblage functioning. It seems that the multispecies character of the benthic fisheries results in a balanced trait removal, while management should regulate the effects of purse-seine fisheries on the fisheries assemblage functioning. Further investigation of the functions that fishing may remove from the ecosystem could contribute to understanding the effects of fishing and reveal overlooked aspects useful for the improvement of fisheries management. [ABSTRACT FROM AUTHOR]

An important task of natural resource management is deciding amongst alternative policy options, including how interventions will affect the dynamics of resource exploitation. Yet predicting the behaviour of natural resource users in complex, changeable systems presents a significant challenge for managers. Scenario planning, which involves thinking creatively about how a socio-ecological system might develop under a set of possible futures, was used to explore uncertainties in the future of the Indian Ocean tuna purse seine fishery. This exercise stimulated thinking on how key social, economic and environmental conditions that influence fleet behaviour may change in the future, and how these changes might affect the dynamics of fishing effort. Three storylines were explored: an increase in marine protection, growing consumer preference for sustainable seafood, and depletion of tuna stocks. Comparing across several possible future scenarios, a number of critical aspects of fleet behaviour were identified that should be important considerations for fishery managers, but which are currently poorly understood. These included a switch in fishing practices, reallocation of effort in space, investment in new vessels and exit from the fishery. Recommendations for future management interventions in the Indian Ocean were offered, along with suggestions for research needed to reduce management uncertainty. [ABSTRACT FROM AUTHOR]

Modern commercial fisheries are heavily dependent on the input of fossil fuels throughout their supply chains, particularly diesel inputs to fishing vessels. Fuel use intensity of fisheries varies with regard to target species, gears employed, region of fishing, technologies used, skipper behaviour, and other factors. Those fisheries that consume relatively less fuel not only have a lower carbon footprint, up to the point of landing, but are also in a favourable position to meet future fuel and emissions regulations, and may be more resilient to the effects of volatile fuel prices and limited oil resources. We measured fuel inputs to purse seining vessels targeting primarily skipjack ( Katsuwonus pelamis ) and yellowfin ( Thunnus albacores ) tuna. Data reported represent 28% of worldwide landings of skipjack and yellowfin by purse seiners in 2009. These vessels burned, on average, 368 L of fuel per tonne of wet weight landings. This corresponds to a fuel-related carbon footprint of 1.1 kg CO 2 per landed kg of tuna, lower than that of average marine capture fisheries as well as most forms of land-based animal protein production. Interestingly, the use of FADs in purse seine fisheries for tuna was found to be inversely correlated with efficiency, going against conventional logic that FAD use improves efficiency. This study is the largest snapshot of tuna fuel inputs to date, providing a baseline against which future performance can be measured, and an indicator for consumers concerned about the carbon footprint of their food choices. [ABSTRACT FROM AUTHOR]

Highlights: [•] In 2013 the EU proposed no discarding ban for the new CFP. [•] Difference between total catches (Illegal, Unreported, Unregulated catches -IUU) and landings is significant. [•] Total catch is 36% higher (range 28.2-41.5%) than officially reported landings. [•] Trawl account for the largest part of unreported catches, followed by multi-gear and purse seine fisheries. [•] IUU amounts have implications for sustainability and balance of trade. [Copyright &y& Elsevier]

Galicia (NW Spain) is an important fishing region with a high potential for cetacean–fishery interactions. Cetacean depredation on catch and damage to fishing gear can potentially lead to substantial economic loss for fishers, while cetacean bycatch raises conservation concerns. With the aim of gathering information on the types and scale of interactions and of suggesting possible management strategies, we conducted face-to-face interviews with fishers in local fishing harbours, in particular to identify specific problematic interactions and to quantify the level of economic loss and bycatch rates associated with these interactions. We found that cetacean–fishery interactions are frequent, although damage to catch and fishing gear by cetaceans was mostly reported as small. Nevertheless, substantial economic loss can result from common bottlenose dolphins (Tursiops truncatus) damaging coastal gillnets and from short-beaked common dolphins (Delphinus delphis) scattering fish in purse-seine fisheries. Cetacean bycatch mortality was reported to be highest for trawls and set gillnets, and probably exceeds sustainable levels for local common and bottlenose dolphin populations. Although interview data may be biased due to the perceptions of interviewees, and therefore should be interpreted with care, the methodology allowed us to cover multiple sites and fisheries within a reasonable time frame. Minimizing cetacean–fishery interactions requires the implementation of case-specific management strategies with the active participation of fishers. For set gillnet and purse-seine fisheries, the use of acoustic deterrent devices (pingers) may prevent cetaceans from approaching and getting trapped in the nets. For trawl fisheries, where bycatch appears to be particularly high at night in water depths of 100–300 m, possible solutions include the implementation of time/area closures and the relocation of some fishing effort to deeper waters. [ABSTRACT FROM PUBLISHER]

Purpose: The purse seine fishery for sardine is the most important fishery in Portugal. The aim of the present study is to assess the environmental impacts of sardine fished by the Portuguese fleet and to analyse a number of variables such as vessel size and time scale. An additional goal was to incorporate fishery-specific impact categories in the case study. Methods: Life Cycle Assessment methodology was applied, and data were collected from nine vessels, which represented around 10 % of the landings. Vessels were divided into two length categories, above and below 12 m, and data were obtained for the years 2005 to 2010. The study was limited to the fishing phase only. The standard impact categories included were energy use, global warming potential, eutrophication potential, acidification potential and ozone depletion potential. The fishery-specific impact categories were overfishing, overfishedness, lost potential yield, mean trophic level and the primary production required, and were quantified as much as possible. Results and discussion: The landings from the data set were constituted mainly by sardine (91 %), and the remainders were other small pelagic species (e.g. horse mackerel). The most important input was the fuel, and both vessel categories had the same fuel consumption per catch 0.11 l/kg. Average greenhouse gas emissions (carbon footprint) were 0.36 kg CO eq. per kilo sardine landed. The fuel use varied between years, and variability between months can be even higher. Fishing mortality has increased, and the spawning stock biomass has decreased resulting in consequential overfishing for 2010. A correlation between fuel use and stock biomass was not found, and the stock condition does not seem to directly influence the global warming potential in this fishery. Discards were primarily non-target small pelagic species, and there was also mortality of target species resulting from slipping. The seafloor impact was considered to be insignificant due to the fishing method. Conclusions: The assessment of the Portuguese purse seine fishery resulted in no difference regarding fuel use between large and small vessels, but differences were found between years. The stock has declined, and it has produced below maximum sustainable yield. By-catch and discard data were missing but may be substantial. Even being difficult to quantify, fishery impact categories complement the environmental results with biological information and precaution is need in relation to the stock management. The sardine carbon footprint from Portuguese purse seine was lower than that of other commercial species reported in. [ABSTRACT FROM AUTHOR]

South Africa's small pelagics fishery is currently the largest in volume and second largest in value in the southern Benguela. It exploits short-lived, small pelagic fishes such as anchovy (for reduction into fish meal and oil) and sardine (for reduction as well as human consumption through canned products), and to a lesser extent redeye round herring and mesopelagics, largely for reduction. We explore the recent history (1940s to present) of the social-ecological system around this fishery. The natural subsystem, at the scales of the ocean environment and the ecosystem, is characterized by high interannual and documented decadal-scale variability. We characterize the human social subsystem at the scales of the fishing industry, legislation, and west coast fishing towns, and demonstrate interdependencies between the natural and social subsystems by following system-scale changes. The pelagic fishing industry has evolved to deal with variability through consolidation, diversification, and range expansion. Legislation has increasingly looked for conservation of the resource while ensuring economic viability of the industry, and hence factory- and vessel-related jobs. Fishing communities under apartheid stayed largely dependent on company-generated infrastructure, combining seasonal employment in the fishing factories with inshore fishing, targeting rock lobster and line fish. While the pelagic industry persisted and communities survived, the resource base for both offshore and inshore fisheries gradually eroded. The advent of democracy in the mid-1990s brought allocation of long-term fishing rights to individuals or companies under conditions of depleted inshore resources aggravated by a shift in the distribution of pelagic fish away from the west coast towards the Cape south coast in the second half of the 1990s. The resultant loss of employment and fishing rights in the inshore has generated community coping strategies that include poaching and challenges to the current Marine Living Resources Act, while the industry continues to expand by range and species, possibly further eroding the resource base. We argue that the situation in the pelagic social-ecological system is indicative of further loss of resilience to change. Coping with future longterm, system-scale change will necessitate careful long-term scenario planning among the various interest groups involved, joint research being one way to overcome the communications breakdown and initiate the joint planning process. [ABSTRACT FROM AUTHOR]

This study analyzes the determinants of the choice of remuneration system and examines their influence on the economic performance of fisheries. The purse seine fisheries in Khanh Hoa province, Vietnam, are used as the study case, with data collected from 158 fishing households in 2005 and 2008. The principal-agent framework and the propensity score-matching technique are employed for the analysis. We demonstrate that insurance incentive-based problems are the rationale for the coexistence of share contracts and flat-wage contracts, even though share contracts bring greater economic benefit to both vessel owners and crew members. Crew members are found to be risk averse. Crew size and residence are important factors that influence the choice of contracts. Compared with flat-wage contracts, small share-contracted vessels are more efficient in managing the operating costs, while large ones are more efficient in yielding a high catch. [ABSTRACT FROM AUTHOR]

Abstract: Technical efficiency, uncertainties in data quality and natural fluctuations in fishing stocks constitute potential sources of fishing vessel inefficiency. Moreover, debate is on-going as to whether the skill of the fishermen (“skipper effect”) is an underlying actor in fishing efficiency. Therefore, this article monitors, calculates and quantifies the inefficiency caused by the “skipper effect”, if any, through the use of data envelopment analysis (DEA), with the aim of determining whether best practice target operational values in DEA, and their associated environmental impact reductions through LCA+DEA methodology, are achievable beyond the theoretical baseline they involve. A window analysis model is applied to the US menhaden fishery, a purse seining fleet with high homogeneity, since it is owned by the same company, with similar vessel and management characteristics. Results revealed relevant inefficiency levels in the four ports assessed, suggesting the existence of a “skipper effect” in all of them. Strong variances between vessels were identified, not only on an annual mean basis, but also per week of study. These variances could be attributed to random variation through time, if it were not for the fact that best performing vessels managed to repeatedly perform at high efficiency rates throughout the period. Moreover, standard deviations of low efficiency vessels were higher in all ports. Consequently, best performing targets calculated in LCA+DEA may be difficult to achieve in fleets where skipper skill strongly influences the sources of inefficiency. In these cases, the results suggest that resource minimization should be linked to specific measures to improve the individual skills of low performing vessels to attain best practice targets. [Copyright &y& Elsevier]

The marine fishery in Senegal, West Africa, is a major source of employment and food security. It currently faces the consequences of ecological degradation. This paper examines job satisfaction among small-scale purse seine fishers, who constitute one of the dominant fishing métiers in Senegal. The research sample consists of 80 purse seine fishers in three locations along the coast with varied degrees of urbanisation. The findings suggest that purse seine fishers are generally satisfied with the extent to which the fishery meets their Social Needs and Self-Actualisation. They are dissatisfied, however, with the degree to which Basic Needs are met, with the way in which Management is carried out, and-to a lesser extent-with the condition of the natural environment. However, the study shows significant differences between the more rural and urbanised settlements. These are most pronounced with regard to the willingness to change fishing type, move to another profession or advise a young person to enter fishing. [ABSTRACT FROM AUTHOR]

I analyze drivers of investment in a fishery with tradable quotas. Theory predicts that tradable quotas increase efficiency because efficient firms buy quotas from less efficient firms. I identify what drives investment, using data on Norwegian purse seiners. Results show that while the basic economic investment model explains investment within firms, it does not explain differences between firms. These differences are explained by other firm-specific factors such as geographical location, whether it is a family firm, and prices paid for quotas. Consequently, investment strategies are not necessarily driven by efficiency considerations, and quota trade may not increase allocative efficiency. [ABSTRACT FROM AUTHOR]

Abstract: Overexploitation of bycatch and target species in marine capture fisheries is the most widespread and direct driver of change and loss of global marine biodiversity. Bycatch in purse seine and pelagic longline tuna fisheries, the two primary gear types for catching tunas, is a primary mortality source of some populations of seabirds, sea turtles, marine mammals and sharks. Bycatch of juvenile tunas and unmarketable species and sizes of other fish in purse seine fisheries, and juvenile swordfish in longline fisheries, contributes to the overexploitation of some stocks, and is an allocation issue. There has been substantial progress in identifying gear technology solutions to seabird and sea turtle bycatch on longlines and to direct dolphin mortality in purse seines. Given sufficient investment, gear technology solutions are probably feasible for the remaining bycatch problems. More comprehensive consideration across species groups is needed to identify conflicts as well as mutual benefits from mitigation methods. Fishery-specific bycatch assessments are necessary to determine the efficacy, economic viability, practicality and safety of alternative mitigation methods. While support for gear technology research and development has generally been strong, political will to achieve broad uptake of best practices has been lacking. The five Regional Fisheries Management Organizations have achieved mixed progress mitigating bycatch. Large gaps remain in both knowledge of ecological risks and governance of bycatch. Most binding conservation and management measures fall short of gear technology best practice. A lack of performance standards, in combination with an inadequate observer coverage for all but large Pacific purse seiners, and incomplete data collection, hinders assessing measures'' efficacy. Compliance is probably low due to inadequate surveillance and enforcement. Illegal, unreported and unregulated tuna fishing hampers governance efforts. Replacing consensus-based decision-making and eliminating opt-out provisions would help. Instituting rights-based management measures could elicit improved bycatch mitigation practices. While gradual improvements in an international governance of bycatch can be expected, market-based mechanisms, including retailers and their suppliers working with fisheries to gradually improve practices and governance, promise to be expeditious and effective. [Copyright &y& Elsevier]

This work is proposing a dynamic model governing the evolution with respect to time of the sardine (Sardina pilchardus) stock in the Atlantic coast between Cantin Cape and Blanc Cape in the North West Africa, which is harvested by two different fishing fleets. We assume that the sardine stock is distributed on two closed zones and targeted by a composite fleet: The Moroccan purse seiners which can move between the fishing regions and a fleet of deepsea trawlers composed mainly of foreign vessels and operating in the southern zone. The model is a set of 5 Ordinary Differential Equations (ODE) with two components: a stock component which describes the sardine evolutions in its 2 zones of distribution, and a component governing the dynamics of the fishing efforts. By using some aggregation methods, we reduce the system to a set of 4 ODE, and then we study analytically the existence and the asymptotic stability of the equilibrium points. The parameters of the stock dynamics and harvest are then estimated using models fitting techniques based on a set of available data. The conditions leading to sustainable fisheries are then simulated. Interpretations of our results can be used by the authority responsible of fishery management, as general recommendations for a better management of Moroccan fisheries. [Copyright &y& Elsevier]

Abstract: Great Frigatebirds (Fregata minor) are large tropical seabirds that rely primarily on sub-surface predators such as tunas or cetaceans to capture their prey. We studied the foraging movements of 14 Great Frigatebirds breeding on Aldabra Island (9.4°S, 46.4°E), the largest colony in the Indian Ocean. This colony is located at more than 500km from the main fishing grounds of a very important industrial purse-seine fishery targeting surface-dwelling tunas. Despite their slow flight speeds (16kmh−1), frigatebirds are able to forage at more than 1000km from the colonies when breeding, using 2500–4750km long foraging loops over oceanic waters. All trips were directed to the north of the island up to the equator. Foraging bouts, indicated by reduced flight speeds, were rare and located throughout the trips. Foraging spots tended to be more frequent on higher surface chlorophyll concentration and in association with some cyclonic vortices. However, mesoscale activity is relatively weak between Aldabra and the equator and the chlorophyll variability is mostly the result of wind-mixing processes during the southwest monsoon. These results suggest that frigatebirds forage for widely distributed resources to the north of Aldabra. The northernmost foraging bouts were located in the vicinity of the purse-seine fishing grounds, but without a significant overlap between frigatebirds and tuna fleets. The results of the study are compared with those from another population at Europa Island (22.3°S, 40.3°E) where birds were foraging on predictable features, the edge of cyclonic eddies that are marked in the Mozambique Channel. We discuss the consequences of the reliance of populations on contrasted oceanographic conditions on foraging strategies and on the evolution of life histories in these long-lived animals in a changing climate, as well as the possible effects of overfishing on frigatebird populations. [Copyright &y& Elsevier]

Fisheries bycatches and discards constitute a significant problem in many fisheries worldwide. Unlike the pelagic purse-seine, the demersal purse seine usually targets high commercial value demersal species such as sea breams (e.g., Diplodus spp., Pagellus spp., Sparus aurata) and the European sea bass (Dicentrarchus labrax), while discards consist mainly of pelagic species and juveniles of the above mentioned species. In order to evaluate the efficiency of a selectivity device in reducing bycatch and consequently of discards in a demersal purse seine fishery, experimental deployments were carried out. The bycatch reducing device (BRD) consisted in the use of a panel of diamond-shaped mesh netting of 70 mm stretched mesh in the posterior part of the purse seine. Data from 61 experimental fishing trials allowed the evaluation of discards, with Scomber japonicus, Boops boops, Sardina pilchardus, Diplodus bellottii and Belone belone being the main discarded species. The mean discard ratio per set was 0.49 (± 0.30 standard deviation). The causes for discarding were also identified, with low commercial value being the most important reason. The results of the trials with BRD, were promising, with an average of 49% (± 24%) of the fish escaping per set, especially from those species that are most discarded. Overall, the use of this method for reducing discards can be considered positive for the following reasons: there is no need for structural modification of the fishing gear, the BRD is easy to deploy, and it is efficient in terms of species, sizes and quantities of fish that manage to escape. It therefore has significant benefits for the demersal purse seine fishery and possibly for other "métiers" as well. [ABSTRACT FROM AUTHOR]

Lennert-Cody, C. E., Roberts, J. J., and Stephenson, R. J. 2008. Effects of gear characteristics on the presence of bigeye tuna (Thunnus obesus) in the catches of the purse-seine fishery of the eastern Pacific Ocean. – ICES Journal of Marine Science, 65: 970–978.Overfishing of bigeye tuna in the eastern Pacific Ocean has motivated a search for a practical means of reducing the catch of bigeye tuna in mixed species aggregations. To explore the effects of gear characteristics on the catch of bigeye tuna, a classification algorithm for the presence/absence of bigeye tuna catch in purse-seine sets on floating objects is developed, using the tree-based method, random forests. Although the location of the set was the strongest determinant of bigeye tuna catch with these data, bigeye tuna in some areas were more likely to be caught on floating objects with greater underwater depths and with deeper purse-seines. Misclassified sets that caught bigeye tuna were concentrated within certain vessels, suggesting the existence of additional vessel effects. Results indicate that fishers may avoid catching bigeye tuna in some areas by changing the depth of the material hanging from the floating object and the actual fishing depth of the purse-seine, or by moving to other fishing areas. Nonetheless, given the complexity of configuring a purse-seine, and the difficulties associated with monitoring compliance with gear regulations, fishery-wide gear restrictions would be problematic. [ABSTRACT FROM PUBLISHER]

An observer's sampling scheme, that employed fisheries scientists onboard fleet vessels was used to examine temporal fishing tactics and strategies affecting catches of the purse seine fishery in the Mediterranean. The month, water depth and the fishers' behavior were found to have an effect on total and Trachurus spp. retained catches, with fishers' behavior explaining the largest percentage of the data variation. The distance of the fishing ground from port and the market price modulated both the retained catches and the fishing location choice. Results confirmed that fishers while in a specific fishing ground developed strategies that would allow them to retain, and thus land, the best possible combination of landings × market value. The current findings also revealed that, when constrained by physical and economic conditions, fishers preferred to minimise risk rather than maximize landings. The observed major switches in fishing strategy were attributed to fishers' risk attitude response towards higher profitability. As the Mediterranean fishery system is mainly based on control effort and technical measures regimes, the current findings are discussed in the light of the need to consider additional information to management plans and decisions. [ABSTRACT FROM AUTHOR]

The Cape horse mackerel Trachurus trachurus capensisis one of Namibia's most valuable fish stocks, and an important component to the diet of Cape fur seals, Arctocephalus pusillus pusillus,off northern Namibia. The level of overlap in the utilization of this resource between seals and the purse-seine fishery was investigated using two overlap indices. For high overlap measures, seals and the purse-seine fishery utilized age-2 horse mackerel. For low overlap measures, seals mainly consumed age-0 fish whereas the fishery caught age-2 fish. Both indices were adjusted by the proportion of horse mackerel in the seal diet, with the assumption that the proportion consumed by the seals reflects the abundance of horse mackerel in the coastal waters of Cape Cross, Namibia. Both unadjusted and adjusted overlap indices showed that overlap between seals and the fishery in their utilization of juvenile horse mackerel was high only at times when horse mackerel abundance was high, and low when abundance was small. Confidence intervals and significance testing were included. Overall, there was little overlap between seals and the purse-seine fishery. This study provides important information that should be taken into account in the management of the horse mackerel resource. [ABSTRACT FROM AUTHOR]

Observations from the purse seine fishery off northern Portugal are used to describe the early dynamics of sardine ( Sardina pilchardus) stress reactions and identify likely stressors during the commercial fishing operation. Sardine blood and muscle were sampled from the onset of fishing (school identification and encircling) to the end of fish transfer onboard (90–120 min later). The evolution of haematocrit, haemoglobin, cortisol, glucose, ionic concentrations, ATP and its catabolites were modelled using linear mixed models as a function of time spent in the net, biological (sex, reproductive state and condition) and operational variables (catch, light level and phase of fishing operation). Significant linear trends with time were detected for most stress variables and mean concentrations after 2 h in the net were similar to literature values corresponding to acute stress reactions for teleosts. Biological variables were rarely significant and explained a small proportion of variation, while operational variables were never significant. For each stress variable, levels varied considerably between trips but the temporal evolution was common across trips. Random trip effects were uncorrelated among most biochemical variables, suggesting that distinct factors affected each stress variable during the sampled trips. However, the linear trend with time spent in the net observed for most stress variables indicates that the duration of the fishing operation is an important stressor in purse seine fishing due to the progressive water volume restriction, crowding and manipulation associated to the fishing method. [ABSTRACT FROM AUTHOR]

The analysis of technical efficiency in developing country agriculture is well established but has been overlooked for developing country commercial marine fisheries. Policies raising technical efficiency in agriculture are viewed as uniformly positive but are a mixed blessing in fisheries due to the open-access property right and common-pool resource. This study explores this contradiction and policies aimed to promote sustainable development and management of renewable common pool resources through a case study of the Java Sea purse seine fishery. Season of the year rather than fisher or vessel characteristics primarily determines technical efficiency. The results are contrasted with developing country agriculture and conclusions drawn for fisheries development strategies. [ABSTRACT FROM AUTHOR]

The relationship between productive efficiency and sustainable development of fishing industries in developing countries has received little attention. Ill-structured property rights in common-pool resources lead to a contradiction between private and social technical efficiency, with private and social costs dependent on the level of technical efficiency. Development policies that increase private efficiency can increase the social cost with ill-structured property rights and common-pool resources, and thereby increase social inefficiency. This paper examines this relationship through a case study of the mini purse seine fishery of the Java Sea, and finds that private technical efficiency does not depend on any measurable attributes of human capital, diverges substantially between the peak and off seasons, and differs between vessels more within the off season. [ABSTRACT FROM AUTHOR]

An assessment has been made of the stock conditions of five major component fishery species ( Chrysichthys nigrodigitatus, Chrysichthys auratus, Hemisynodontis membranaceus, Oreochromis niloticus and Schilbe intermedius) exploited with illegal purse-seine (winch-net) gear in the Yeji sector of Lake Volta, Ghana. Chrysichthys nigrodigitatus was clearly found to be overexploited, but the others were being exploited near to, or under, optimum harvest levels. All five species were harvested at an inappropriate age-at-first-capture of ≈ 6 months, suggesting overfishing of young fishes. Consequently, the computed Lm:L∞ ratios were > 0.64. For most fish species, such a ratio implies their exploitation when at early maturity and at very small sizes. The estimated range of mesh sizes in the cod-ends was far lower (5–8 mm) than the legal mesh size of 25 mm, calling for urgent enforcement of rules and regulations. Single-species yield-per-recruit analyses indicated that yields could be improved by the reduction in the current fishing effort. As the fishery of the lake is not segmented to allow fish to be taken by the illegal small-mesh purse seines, studies on the interactions between the different fishery sectors need to be undertaken, alongside the proposed ban of the gear as enshrined in the Fisheries Law of Ghana. [ABSTRACT FROM AUTHOR]

Seabirds are known to make extensive use of fishery waste, a phenomenon that has been particularly well studied in relation to demersal fisheries, especially when operating during daylight hours. Contrarily, very little is known about the importance of predominantly nocturnal fisheries in providing feeding opportunities to seabirds. We considered the particular case of purse seining for small pelagic fish, which takes place basically at night, and assessed the significance of this fishing practice for seabirds off the Ebro Delta (NW Mediterranean). Fieldwork was conducted on board commercial purse seiners (nocturnal activity) in 1997-1998, and was complemented with observations performed on board both commercial bottom trawlers (diurnal activity; 1997 1998) and a research vessel (1999-2000). The purse seine fleet targets small clupeoids, which are attracted and concentrated by the light of a powerful lamp, and then captured using an encircling net. Purse seiners frequently changed fishing area, took very variable catches, and were strongly influenced by the weather. This made the fishery unattractive to most seabird species, which primarily attended purse seiners during the discarding process. This process took place on the way back to port after dawn (i.e. with daylight) during daylight and was quite irregular, thus attracting lower numbers of seabirds than did trawlers. The threatened Audouin's gull Larus audouinii was the only species attending purse seiners regularly at night, capturing live fish concentrated at the sea surface during the hauling process. This is in accordance with the specialisation of this gull in the capture of epipelagic fish at night, which seems facilitated by purse seiners. Indeed, the vessels would favour the direct capture of fish (illumination of the sea surface, concentration of the fish), as well as the location of the shoals (light signalling). The purse seining fishery was especially important for Audouin's gull during... [ABSTRACT FROM AUTHOR]

Data Envelopment Analysis (DEA) studies of fisheries usually apply output oriented capacity utilization based on physical measures. Although physical measures capture important input factors employed in fishing activities (such as boat size, engine power), economic measures directly reflect the cost of inputs employed. This case study investigates whether economic measures are vital or whether capacity efficiency is sufficiently well reflected solely by the use of physical measures. The analysis makes use of a double bootstrap DEA technique and compares input oriented capacity utilization based on physical versus economic measures. The double bootstrap technique was chosen as it allows statistical inference based on the estimated capacity utilization. The results show that economic measures give a lower capacity utilization than that obtained by physical measures. However, no significant difference was found in the capacity utilizations between the two measures. Truncated regression models indicated that factors such as skipper experience and family size did not significantly affect these two measures of capacity utilization at the 5% level. This study concludes that physical variables are capable of capturing the essential economic differences between vessels. [ABSTRACT FROM AUTHOR]

Presents theoretical debates about the skipper effect and contrasts the cultural and economic context of North Atlantic fisheries with a purse seine fishery for mixed tropical species in the Philippines. Purse seining in Batangas; Local models of fishing success; Statistical explanations of the causes of fishing success.

Yellowfin tuna in the western Pacific are harvested as juveniles by purse seiners and as adults by longliners. The study presents estimates of the multi-species harvest technology of these two types of vessel operating in Papua New Guinea's Exclusive Economic Zone. The results, together with price and cost information and estimates of the impact of the purse seine catch on the catch rates of longline vessels are used to perform a benefit/cost analysis of a reallocation of juvenile yellowfin through a one percent decline in purse seine harvest in PNG's EEZ. The marginal benefit of investment in the yellowfin stock is found to exceed that of marginal cost, suggesting that there may be an economic case for a reallocation. [ABSTRACT FROM AUTHOR]