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Many seabirds dive to forage, and the ability to use this hunting technique varies according to such factors as morphology, physiology, prey availability, and ambient light levels. Proficient divers are more able to seize sinking baits deployed by longline fishing vessels and may return them to the surface, increasing exposure of other species. Hence, diving ability has major implications for mitigating incidental mortality (bycatch) in fisheries.Here, the diving behaviour and activity patterns of the most bycaught seabird species worldwide, the white‐chinned petrel (Procellaria aequinoctialis), tracked from Bird Island (South Georgia), are analysed. Three data sources (dives, spatial movements, and immersion events) are combined to examine diverse aspects of at‐sea foraging behaviour, and their implications for alternative approaches to bycatch mitigation are considered.The tracked white‐chinned petrels (n = 14) mostly performed shallow dives (<3 m deep) of very short duration (<5 s), predominantly during darkness, but only 7 and 10% of landings in daylight and darkness, respectively, involved diving, suggesting that surface‐seizing is the preferred foraging technique. Nonetheless, individuals were able to dive to considerable depth (max = 14.5 m) and at speed (max = 2.0 m·s−1), underlining the importance of using heavy line‐weighting to maximize hook sink rates, and bird‐scaring lines (Tori lines) that extend for long distances behind vessels to protect hooks until beyond diving depths. [ABSTRACT FROM AUTHOR]

International labor migrants have been widely studied, particularly on land. However, this anthropological research aims to shed light on the working and living conditions of labor migrants at sea, in the longline fishing industry on the Pacific Ocean based out of Honolulu, Hawaii. When working on a fishing boat, labor migrants encounter two distinct working environments: at port and in international waters. This report will focus on the second of these, a place impossible to monitor and therefore where labor laws have little sway. Rather, the captain plays an integral and important role when it comes to how these workers are treated, and as regards the quality of their working and living conditions. [ABSTRACT FROM AUTHOR]

This study delves into the value chain of Taiwan's distant-water tuna longline fishing industry and evaluates its impact on the country's GDP. Using empirical models, the research covers the period from 2016 to 2019, highlighting variations in the industry and related sectors' contribution to the GDP, which ranged from 0.804% to 0.640%. In response to regulatory challenges, the government has sought to optimize fleet size through vessel reduction. During the same period, the primary fisheries sector was the main contributor to the industry's GDP, with a contribution rate fluctuating between 0.383% and 0.518%. This was followed by contributions from the fisheries input sector (contribution rate: 0.144% to 0.161%) and the marketing and service sectors (contributing 0.090% to 0.100% to the fisheries GDP). The findings suggest that the revenue of distant-water tuna fishing companies primarily derives from the direct sales of fish products. However, operational costs are continually increasing with rising international oil prices and ethical concerns surrounding seafood sourcing. Therefore, the Taiwanese government should promote expanded participation of companies in the processing and service marketing sectors. SoonYi, an exemplary company, has successfully integrated primary production, processing, and marketing operations, demonstrating the effectiveness of this approach. By aligning with evolving international market demands, adhering to rigorous standards like the Marine Stewardship Council, and prioritizing the rights of fishing workers, tuna fishing companies can elevate the value of seafood products and strengthen Taiwan's position as a leader in the distant-water tuna fishing sector. [ABSTRACT FROM AUTHOR]

The length‐weight relationships were estimated for three reef fish species caught in the Gulf of Mannar, India using experimental longlines. The longline fishing took place from December, 2019 to September, 2021 in fortnightly intervals, using longlines (2400 m, 2700 m and 3360 m each), equipped with each 600 various "J" type fishing hooks (straight, reversed, kirbed). The hook sizes used were standard size numbers 6, 9, and 12. The longlines fabricated with polyamide monofilament line were operated from 20 to 50 m depth for 3–5 hours each time. Overall, 81,000 hooks were deployed in 45 fishing trials. The total length and total weight of the combined sex group was recorded nearest to 0.1 cm and 0.01 g, respectively. By using the logarithmic transformed data, linear regression analysis was performed to calculate a and b values for three fish species to establish length‐weight relationships. The parameters for the length‐weight equations for three species are provided along with respective coefficient of correlation and the 95% confidence intervals. A new maximum total length was recorded for two grouper species, viz., Epinephelus faveatus (36.5 cm) and Cephalopholis urodeta (46.0 cm). [ABSTRACT FROM AUTHOR]

Copyright of South China Fisheries Science is the property of South China Fisheries Science Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This study concerns a model of the fuel consumption and emissions from the bottom longline fishing fleet at Rio de Janeiro State, Brazil with data comprised vessel and engine characteristics, fuel consumption, landings and fishing trip duration of seventeen longliners operating in Rio de Janeiro between 2015 and 2016. The operational pattern was investigated for this fleet, based on an empirical approach to model the propulsion power requirements of the typical longliner fishing vessel. The current propulsion and power plants of the longliner fishing vessels under consideration are compared with alternative designs by estimating fuel consumption for the different models of propulsion systems. When the operational pattern evaluation is taken into account, it indicates the future potential for diesel-electric propulsion for longliner fishing vessels, as a result of a reduction in fuel consumption. [ABSTRACT FROM AUTHOR]

Albatrosses are among the most threatened seabird species. Often entangled in gillnets or hooked while longline fishing gear is being set, albatrosses are affected by fishing. This is assumed to be especially true in cases where illegal longline fishing vessels are involved, as they are less likely to implement the bycatch mitigation measures implemented to reduce the risk of albatrosses being caught on their hooks. This is the assumption that was tested in the current study, which uses environmental criminology as its guiding theoretical framework. Using the spatial units of one-half-degree by one-half-degree longitude/latitude cells, this research examined the patterns of concentration of potentially illegal longlining efforts and their relationships to commercially sought-out and illegally caught (i.e., CRAAVED—concealable, removable, abundant, accessible, valuable, enjoyable, disposable) fish species concentrations, as well as their effects on the average risk of albatrosses. The results indicated that (a) potentially illegal longlining activity is spatially concentrated; (b) this concentration is exhibited in areas with the highest concentrations of the presence of CRAAVED fish; and (c) the average risk score of albatrosses, as measured by their International Union for Conservation of Nature (IUCN) Red List status, is significantly higher in the areas where illegal longlining vessels are found controlling for the activities of legal longlining vessels. These findings provide strong grounding that illegal longline fishing poses a particularly serious threat to the survival of albatrosses. These activities, however, are not randomly spread across the vast oceans, but rather are highly spatially concentrated. Therefore, the bird conservation lobby should work closely with regional fisheries management organizations to devise and implement targeted interventions aimed at reducing potential illegal longline fishing, which, in turn, will likely have positive effects on albatrosses.

Climate-driven expansions of ocean hypoxic zones are predicted to concentrate pelagic fish in oxygenated surface layers, but how expanding hypoxia and fisheries will interact to affect threatened pelagic sharks remains unknown. Here, analysis of satellite-tracked blue sharks and environmental modelling in the eastern tropical Atlantic oxygen minimum zone (OMZ) shows shark maximum dive depths decreased due to combined effects of decreasing dissolved oxygen (DO) at depth, high sea surface temperatures, and increased surface-layer net primary production. Multiple factors associated with climate-driven deoxygenation contributed to blue shark vertical habitat compression, potentially increasing their vulnerability to surface fisheries. Greater intensity of longline fishing effort occurred above the OMZ compared to adjacent waters. Higher shark catches were associated with strong DO gradients, suggesting potential aggregation along suitable DO gradients contributed to habitat compression and higher fishing-induced mortality. Fisheries controls to counteract deoxygenation effects on shark catches will be needed as oceans continue warming. [ABSTRACT FROM AUTHOR]

Electronic monitoring (EM) systems have become functional and cost-effective tools for the conservation and sustainable harvesting of marine resources. EM is an alternative to on-board observers, which produces video segments that can subsequently be reviewed by analysts. It is currently used in a range of fisheries. There are two major challenges to the widespread adoption of EM. One is the large storage requirement for the video footage recorded and the other is the long time required by analysts to review the video footage. We propose an automated catch event detection framework to address these challenges. Our solution, based on deep learning techniques, automatically extracts video segments of catch events, which substantially reduces storage space and review time by analysts. Here, we demonstrate the framework using video footage from three longline fishing trips. The system recalled nearly 100% of the catch events across all trips. [ABSTRACT FROM AUTHOR]

Albatrosses are the iconic aerial wanderers of the oceans, supremely adapted for long-distance dynamic soaring flight. Perhaps because of this they are considered poorly adapted for diving 1 , in contrast to many smaller shearwater and petrel relatives, despite having amphibious eyes 2 , and an a priori mass advantage for oxygen-storage tolerance 3. Modern biologging studies have largely confirmed this view 4,5 , casting doubt on earlier observations using capillary tube maximum depth gauges 1 , which may exaggerate depths, and emphasising albatrosses' reliance on near-surface feeding. Nevertheless, uncertainty about albatross diving remains an important knowledge gap since bycatch in human fisheries (e.g. birds becoming hooked when diving for longline bait fish) is thought to be driving many population declines in this most threatened group of birds 6. Here we show, using miniature electronic depth loggers (TDRs), that black-browed albatross, Thalassarche melanophris , can dive to much greater depths (19 m) and for much longer (52 s) than previously thought — three times the maxima previously recorded for this species (6 m and 15 s), and more than twice the maxima reliably recorded previously for any albatross (from 113.7 bird-days of tracking 4,5,7). Further evidence that diving may be a significant behavioural adaptation in some albatrosses comes from co-deployed 3-axis accelerometers showing that these deeper dives, which occur in most individuals we tracked, involve active under-water propulsion without detectable initial assistance from momentum, sometimes with bottom phases typical of active prey pursuit. Furthermore, we find (from co-deployed GPS) that diving occurs primarily in the distal portions of long-distance foraging trips, with deeper dives occurring exclusively during daylight or civil twilight, confirming the importance of visual guidance. Albatross are surprisingly deep divers, suggesting an unforeseen behavioural flexibility that could influence bycatch risk in human fisheries, a key factor in many species' decline. Using miniature biologging technologies, Guilford et al. recorded black-browed albatross diving self-propelled to 19 m (52 s) — more than twice previous reliable records. [ABSTRACT FROM AUTHOR]

Copyright of South China Fisheries Science is the property of South China Fisheries Science Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Blackbelly rosefish Helicolenus dactylopterus (Delaroche, 1809) is one of the most important species of the demersal/deep‐water assemblages fished in the NE Atlantic Ocean (Azores archipelago). However, there is insufficient information about the stock structure of this species to support analytical resource assessments and it is currently managed with a precautionary approach. Here, we examine the depth and temporal distribution, size composition, sex, and movement patterns of blackbelly rosefish in order to test the hypothesis that the stock structure in the Azores region comprises different local management units (MUs). We also evaluate annual abundance indices and size composition from scientific surveys and commercial landings over the past c. 25 years for an assessment of the species' vulnerability to bottom longline fishing pressure. The greatest abundance occurred in seamount areas at 350–800 m depth. Larger individuals were mainly found in deeper waters, and no sexual segregation by depth was observed. Tagging results indicated a strongly sedentary behavior and an intraregional separation among populations. Although the abundance pattern and size composition were very similar over time, this species is particularly vulnerable to overfishing due to its biological characteristics (long life, large size, late maturity, slow growth, and low mortality rate). Proper monitoring and management of its exploitation should be a priority. Exploratory analysis for analytical assessment should be performed under the assumption of local MUs. Further oceanographic research is needed to understand larval transport and mixing of populations. [ABSTRACT FROM AUTHOR]

Sediment oxygen demand (SOD) and benthic nutrient fluxes were measured at five sites using an in situ benthic chamber: fish farm (FF), oyster farm (OF), Tongyeong Marine Science Station (TMSS), and two controls (FF-C and OF-C) June 27–July 1, 2017, to assess the impact of aquaculture on coastal waters of southern Korea. The net oxygen production rate of the epiphyte community attached to farming facilities was also measured using an oxygen microsensor to quantify the potential contribution of organic matter to bottom sediment. The SODs at the FF and OF were − 155.2 ± 0.2 m−2 day−1 and − 88.6 ± 0.1 m−2 day−1 respectively, more than twice those of the control sites (FF-C and OF-C). The benthic fluxes of ammonium and phosphate at the fish farm were 12.7 mmol m−2 day−1 and 3.3 mmol m−2 day−1, respectively, which were ~ 10 times higher than those of the control sites and ~ 1.5 times higher than at the OF site. The benthic N and P fluxes accounted for 128% and 501%, respectively, at FF and 89% and 70% of N and P requirements, respectively, at OF for primary production. This suggests that aquaculture activities result in an excess supply of nutrients to the water column, thereby inducing eutrophication in the coastal ecosystem. Potentially, the net production of organic carbon by the epiphyte community yielded about 65 mmol C m−2 day−1, which suggests that organic matter produced by epiphytic communities substantially contributed to benthic respiration. Thus, the commercial finfish and oyster farms increased SOD and benthic nutrient flux, but at a conservatively managed aquaculture (TMSS), there were minimal benthic impacts. [ABSTRACT FROM AUTHOR]

The identification of geographic areas where the densities of animals are highest across their annual cycles is a crucial step in conservation planning. In marine environments, however, it can be particularly difficult to map the distribution of species, and the methods used are usually biased towards adults, neglecting the distribution of other life‐history stages even though they can represent a substantial proportion of the total population.Here we develop a methodological framework for estimating population‐level density distributions of seabirds, integrating tracking data across the main life‐history stages (adult breeders and non‐breeders, juveniles and immatures). We incorporate demographic information (adult and juvenile/immature survival, breeding frequency and success, age at first breeding) and phenological data (average timing of breeding and migration) to weight distribution maps according to the proportion of the population represented by each life‐history stage.We demonstrate the utility of this framework by applying it to 22 species of albatrosses and petrels that are of conservation concern due to interactions with fisheries. Because juveniles, immatures and non‐breeding adults account for 47%–81% of all individuals of the populations analysed, ignoring the distributions of birds in these stages leads to biased estimates of overlap with threats, and may misdirect management and conservation efforts. Population‐level distribution maps using only adult distributions underestimated exposure to longline fishing effort by 18%–42%, compared with overlap scores based on data from all life‐history stages.Synthesis and applications. Our framework synthesizes and improves on previous approaches to estimate seabird densities at sea, is applicable for data‐poor situations, and provides a standard and repeatable method that can be easily updated as new tracking and demographic data become available. We provide scripts in the R language and a Shiny app to facilitate future applications of our approach. We recommend that where sufficient tracking data are available, this framework be used to assess overlap of seabirds with at‐sea threats such as overharvesting, fisheries bycatch, shipping, offshore industry and pollutants. Based on such an analysis, conservation interventions could be directed towards areas where they have the greatest impact on populations. [ABSTRACT FROM AUTHOR]

Two of the largest protected areas on earth are U.S. National Monuments in the Pacific Ocean. Numerous claims have been made about the impacts of these protected areas on the fishing industry, but there has been no ex post empirical evaluation of their effects. We use administrative data documenting individual fishing events to evaluate the economic impact of the expansion of these two monuments on the Hawaii longline fishing fleet. Surprisingly, catch and catch-per-unit-effort are higher since the expansions began. To disentangle the causal effect of the expansions from confounding factors, we use unaffected control fisheries to perform a difference-in-differences analysis. We find that the monument expansions had little, if any, negative impacts on the fishing industry, corroborating ecological models that have predicted minimal impacts from closing large parts of the Pacific Ocean to fishing. There are concerns that expansion of marine protected areas could have negative effects on the fishing industry. Here Lynham et al. demonstrate that the expansion of two of the world's largest protected areas did not have a negative impact on catch rates in the Hawaii longline fishery. [ABSTRACT FROM AUTHOR]

In order to provide relevant information for natural resource management, impact assessment and marine spatial planning, high-resolution estimation of longline fishing gear is needed. Because the use of satellite vessel monitoring system (VMS) data is limited by data access and receiving offshore ship location information. In this paper, based on the data of automatic identification system (AIS) and logbook data of Chinese longline fishing from October to November 2017, a model of fishing detection based on support vector machine (SVM) learning method is established to classify the fishing and non fishing activities in the central and Western Pacific Ocean, to carry out longline fishing and draw fishing effort map in the Western and Central Pacific Ocean. Before constructing a fishing detection model, each AIS point was classified and pre-labeled as potential fishing and non-fishing events by an expert based on information on information on fisheries characteristics as obtained from literature, analysis of the tracks and logbook data. The performance of the fishing detection model was evaluated by the overall accuracy, precision, sensibility and specificity. Fishing intensities were computed from the known fishing positions and the estimated fishing positions were compared with correlation coefficient. The spatial correlation coefficient of fishing intensities and catch data was computed to quantify the extent to which the distribution of longline vessels describes tuna distribution. The results showed that the overall accuracy and the Kappa coefficient of the model training dataset were 95.24% and 0.9, respectively. The precision, sensibility and specificity were 94.74%, 93.44%, 96.56%, respectively. The overall accuracy and the Kappa coefficient of the model testing dataset were 93.85% and 0.87 respectively. The precision, sensibility and specificity were 93.49%, 90.67%, 95.91%, respectively. Then the constructed model was used to identify all the AIS data for 12 longline fishing vessels in the Western and Central Pacific in October and November 2017, with an overall accuracy rate of 83.3% and the Kappa coefficient was 0.67. The precision, sensibility and specificity were 82.33%, 88.32%, and 77.27%, respectively. The longline fishing distinct in October and November 2017 mainly located in 168°E-173°E, 12°S-18°S, and there were three obvious high fishing intensity areas on the map. The spatial distribution of fishing effort was significantly different between October and November. The distribution of fishing intensity in November was closer to the island than in October and the value of fishing intensity in October was lower than November. The fishing intensity information based on the SVM model and logbook data records was highly correlated (r>0.98). The spatial distribution characteristics of the fishing effort of the fishing vessel identified by the SVM model were similar to the known fishing positions. But the fishing intensities were calculated from known fishing positions was higher than that of estimated fishing positions. The spatial correlation coefficients of cumulative fishing effort and catch per unit of effort (CPUE), catch tail, catch weight and number of hooks were 0.68, 0.93, 0.93 and 0.94, respectively. The fishing capacity of fishing vessels based on AIS information mining can also be used as an alternative method for fishery resource analysis. [ABSTRACT FROM AUTHOR]

Longlines bearing "hook timers" (HTs) and alternating circle (15/0 and 17/0) and "J" (10/0) hooks were employed off the coast of Brazil to measure differences in fishing mortality associated with hook type and on-hook time between capture and boarding. A total of 431 HTs were activated, revealing a clear pattern of the increased mortality rate of fishes associated with increased on-hook time. Swordfish had high mortality rates, unlike blue sharks, which had low mortality rates regardless of hook type and the location in which the hook was transfixed. The six species of tunas and billfishes examined in this study showed a strong association between hooking location and the animal's release condition, with reduced mortality associated with individuals hooked externally. Results suggest that knowledge of factors affecting the survival of pelagic fishes caught in longline fisheries may enable the development and adoption of fishing methods to reduce mortality of longline bycatch. [ABSTRACT FROM AUTHOR]

Destructive fishing practices (DFP) and illegal, unreported, and unregulated (IUU) activities result in significant marine ecosystem effects, such as habitat destruction, biomass reduction, bycatch, and waste of resources. They also generate socioeconomic impacts on artisanal fisher coastal populations. Both DFP and IUU are linked to fisheries management system failures and the impossibility of marine surveillance. In this context, from an Ethnoecological approach, the aim of this study was to analyze the local ecological knowledge of fishers from Ilhéus (Bahia), Northeastern Brazil, regarding DFP and IUU fisheries. A total of 59 interviewees pointed to decreased resource catches in recent years, citing increasing fishing efforts and certain types of gear as the main reasons. They also claim that local fishers and fishers from other Brazilian regions have been using banned equipment, such as compressors and lobster nets. In turn, although permitted by law, shrimp trawling and gillnet fishing were reported as being excessively applied and identified as destructive fisheries. Surprisingly, longline fishing was one of the most reported as responsible for excessive catches and for causing decreases in Common dolphinfish catches. This study reinforces the importance of including the knowledge of local fishers and their participation to contribute to fisheries management and resource conservation. In this context, some recommendations are highlighted to reduce the impacts of harmful practices and improve regional fisheries management, summarized as: (i) policy improvement; (ii) fishing monitoring; (iii) incentives; and (iv) enforcement. • This paper explores LEK of artisanal fishers to address DFP and IUU fishing issues. • Artisanal fishers pointed out decreased resource catches due to increased fishing effort and unsustainable practices. • Unequal competition with larger vessels from other regions is noted for the local fishing territory. • Environmental impacts arising from IUU and PPD fisheries are addressed. • Results point to the need for governance improvement, the regulation of DFP and reduced IUU fishing in the region. [ABSTRACT FROM AUTHOR]

Understanding the biology of fishing resources is a basic tool in order to define their adequate administration, and for that, trophic ecology studies gather important information about the spatio-temporal distribution of fish populations and their preys. Using passive fishing tackles such as longline and gillnets, 373 specimens of the gafftopsail sea catfish Bagre marinus were caught from which, 252 stomachs were analyzed. Forty-one food items were identified and classified in different groups of which, fish remains, the fish Anchoa sp, peneid crustaceans, the fish Cathorops mapale, fish eggs and vegetal material were the most frequent ones. The diet analysis indicates that it is an omnivore species. The feeding habits of this ariid, respond to an estuarine gradient in direction south-north, with significant differences between seasons and no significant overlapping between sites. To the north, the peneid crustacean preys are dominant in the diets, apparently due to high salinities of this zone that favor their abundance, while the south zone, characterized by large extensions of mangroves, is apparently an adequate area for a wider spectrum of marine and estuarine preys, particularly fish. [ABSTRACT FROM AUTHOR]

In the Southern Ocean, the impact of environmental changes and increasing human encroachment is causing declines in several populations of seabirds. Amsterdam island (77°33′E; 37°50′S) hosts some emblematic but globally threatened seabird species with alarming population trends. In 2017, concerns about Amsterdam Island's marine biodiversity led to the extension of a marine reserve to the boundaries of the exclusive economic zone (EEZ). Nevertheless, it is unknown whether this protected area is sufficiently large to encompass the most important foraging hotspots of the threatened seabirds, particularly during key stages of their life cycle (e.g. breeding period). We analysed movements of four threatened seabird species using a tracking dataset acquired over several breeding seasons from Amsterdam Island: Amsterdam albatross Diomedea amsterdamensis , sooty albatross Phoebetria fusca , Indian yellow-nosed albatross Thalassarche carteri and northern rockhopper penguin Eudyptes moseleyi. Our objectives were threefold: (1) characterise the at-sea distribution of the above-mentioned populations and delineate the marine Important Bird and Biodiversity Areas (mIBAs) triggered by them; (2) assess the potential threat at-sea by quantifying the overlap between seabird distribution and longline fishing efforts; (3) evaluate the coverage of identified mIBAs by marine protected areas and suggest complementary conservation actions. The identified important areas fell within the boundaries of the EEZ, but vastly exceeded the former reserve. Thus, our results reinforce the justification of the recent expansion of the reserve to the boundaries of the EEZ. However, overall seabird distributions extended beyond the EEZ (5 to 50% of the locations) and we found substantial overlap with longline fishing in the high seas. Our results provide a spatio-temporal envelope of where and when bycatch mitigation and observer coverage of longline fisheries should be mandated and enforced. [ABSTRACT FROM AUTHOR]

Abstract The activity of the Portuguese fishing fleet operating near seamounts of the Madeira Tore geologic complex was analyzed. The main objective is to identify the different fisheries taking place in the area, characterize the spatial patterns of vessels activity and estimate the fishing intensity, thus contributing to better inform management decisions. Vessel Monitoring System (VMS) and e-logbook data for the period 2012–2014 were used. The combined analysis of these data allowed the identification of fishing events and the estimation of the fishing intensity by gear type, as well as the characterization of general patterns relating to fishing operations. A total of 47 vessels displayed fishing activity in the studied area, mainly longliners based either on the mainland or the Madeira archipelago, visiting different seamounts in fishing trips lasting two to three weeks, and a few pole and line bait boats. Bottom and pelagic longlining alternate throughout the year, the former mostly in spring and summer, targeting the wreckfish Polyprion americanus and the European conger , Conger conger , while the latter is carried out in autumn and winter using a surface longline targeting the swordfish Xiphias gladius and a drifting longline set deeper in the water column, targeting the black scabbard fish Aphanopus carbo. A global evaluation of the fishing intensity and estimation of fishing impact in this area calls for the availability of VMS data, e-logbooks and landing declarations from non-Portuguese fleets, making monitoring in these areas a top priority to assess the sustainability of human activities. Highlights • The fishing activity of Portuguese vessels operating in Madeira-Tore (NE Atlantic) was analyzed using VMS and e-logbook data • Several fisheries were identified in the area, differing in intensity and in spatial patterns of vessels activity • For a global evaluation of fishing activity, data on the activity of non-Portuguese fleets need to be made available [ABSTRACT FROM AUTHOR]

A global expansion of satellite-based monitoring is making fisher behavioral responses to management actions increasingly observable. However, such data have been underutilized in evaluating the impacts of fishing on target and non-target fish stocks or the ramifications of management strategies on fishers. We demonstrate how vessel monitoring system (VMS) data can provide a suite of metrics (such as effort) for improving inputs to stock assessments, dynamic delineation of fishing grounds, and evaluation of regulatory or other (e.g., climatic) impacts on fisher performance. Using >1 million VMS records from the Gulf of Mexico grouper-tilefish demersal longline fishery, we first develop a generalized additive modeling approach that predicts fishing duration with ∼85% accuracy. We combine model predictions with logbook data to compare the fishery before and after implementation of a suite of regulatory changes (e.g., a shift to catch share management). We find a large-scale reduction in fleet size, accompanied by reduced fishing effort (duration * number of hooks), shorter trips, lower operational expenses, higher catch rates, and more earnings for those vessels that remained in the fishery. We discuss how the combination of VMS and associated metrics can be expanded for use in management strategy evaluation, parameterizing economic models of fisher behavior, improving fishery-dependent stock assessment indices, and deriving socioeconomic indicators in fisheries worldwide. [ABSTRACT FROM AUTHOR]

• Plastic is one of the main marine pollution sources challenging nature conservation. • In longline fishery, lost snoods contribute to marine plastic pollution. • Use of biodegradable plastic in snoods has potential to reduce plastic pollution. • No significant differences between biodegradable and nylon snoods were found. Pollution from lost, abandoned, or discarded fishing gear is recognized as a global nature conservation concern. Longlining with hooks is a commonly applied fishing method in fisheries around the world. The longline gear consists of a mainline with a number of baited hooks that are attached to it by thinner twine (snoods) which are often made of plastic material such as polyamide (nylon) or polyester that degrades very slowly in the marine environment. During longline fishing, some of the snoods are lost at sea contributing to marine macro- and micro-plastic pollution. The extent of the snood loss is often unknown and can vary between different longline fisheries and fishing grounds. In this study, we estimated and compared the risk for the biodegradable and nylon snood loss in an Adriatic small scale longline fishery. Further, we compared the catch composition and estimated catch efficiency between biodegradable and nylon snoods for capture of common pandora (Pagellus erythrinus), two-banded seabream (Diplodus vulgaris) and axillary seabream (Pagellus acarne). The risk for nylon snood loss in this longline fishery (3 % for each snood for each deployment), demonstrate that the use of more environmentally friendly materials is necessary for nature conservation. No significant differences between the performance of the two materials regarding snood loss rate, hook loss rate, catch efficiency and catch composition were found during short-term usage in the fishery. Based on these results, future long-term testing is encouraged to investigate whether this promising performance of the biodegradable snood material is persistent over longer fishing periods. [ABSTRACT FROM AUTHOR]

Elasmobranchs (sharks, rays, and skates) are caught throughout fisheries globally, leading to over one-third of species being threatened with extinction 1. Oceanic shark populations have undergone an average 71% decline over the last half century, owing to an 18-fold increase in relative fishing pressure 2. Incidental capture or 'bycatch' is a primary driver of population declines, and poses an important challenge for species conservation 3. This threat necessitates mitigation strategies that exist for sharks but are often focussed on haul-back and post-capture effects for longline fishing. We trialled a novel shark bycatch mitigation device ("SharkGuard") in a commercial longline fishery targeting bluefin tuna (Thunnus thynnus), where bycatch consists largely of blue sharks (Prionace glauca) and pelagic stingrays (Pteroplatytrygon violacea). There is an urgent need to reduce bycatch of sharks and rays in fisheries. Doherty, Enever et al. tested the efficacy of a novel bycatch mitigation device, 'SharkGuard' in a longline fishery targeting tuna. Results showed the electrical impulse from the SharkGuard device significantly reduced catch of blue sharks and pelagic stingrays. [ABSTRACT FROM AUTHOR]

Accounting for components of fishing mortality, including post-release mortality (Fr), is necessary for robust assessments of the effects of fishing. Forty-eight blue (Prionace glauca) and 35 silky sharks (Carcharhinus falciformes) were tagged with pop-up satellite archival tags to monitor Fr rates from pelagic longline vessels in the western tropical Pacific Ocean. There is a paucity of Fr studies at low latitudes and identifying factors that significantly explain Fr is critical for understanding fishing mortality. Mean Fr rates were 0.17 [95% CI 0.09-0.30] for blue shark and 0.20 [95% CI 0.10-0.36] for silky shark. When it occurred, Fr was acute with 87% of mortalities within 2 days of release. Several prognostic operational, environmental, biological and handling variables were evaluated to assess their influence on survival outcomes. Using Kaplan-Meier survival curves, logistic regression, accelerated failure time and Cox proportional hazards models to screen variables, the only significant prognostic or risk variable was health condition at haulback. There was close correspondence (~ 83% accuracy) between condition at capture and survival outcomes. Reliable methods to classify at-vessel condition represent an inexpensive and simple metric for estimating both Fr and at-vessel (Fc) mortality rates. Examining Fc rates in detail in longline fisheries using capture information on depth, temperature and dissolved oxygen that may act in synergy with condition code and hooking duration is a research priority. Results suggest that a large proportion of shark survive following release and that Fr rates can be increased by improving the haulback condition of captured sharks. [ABSTRACT FROM AUTHOR]

Stress-related physiological changes and post-release survival of elephant fish ( Callorhinchus milii ) in response to fishing capture and handling were assessed by experimental simulation using several different fishing gears for various periods under controlled laboratory conditions and by repeated blood sampling during a subsequent 72-h period to monitor the animals’ condition. Capture and handling caused physiological changes in elephant fish indicated by elevated plasma lactate, potassium and osmolality and immediately depressed plasma glucose. Maximum values of plasma potassium and osmolality occurred mainly immediately after capture (0 h), and maximum levels of plasma lactate at 0 and 3 h. Elevated plasma lactate concentrations returned to baseline values after 12 h of capture. Minimum levels of plasma glucose were recorded 3 h after capture. Hypoglycaemia followed by hyperglycaemia after stress was recorded. Handling alone significantly increased plasma lactate levels. Gillnet capture caused the greatest physiological stress, followed by longline, and then angling. Immediate mortality was 0% for all capture treatments, but delayed mortality varied widely among the capture treatments. Post-release survival rates were 70% (i.e. 30% delayed mortality) for longline and gillnet depending on fishing duration and 100% (i.e. 0% delayed mortality) for hook and line (angling) provided the animals were returned to the water immediately following capture. The best indicators of poor condition in this species were low plasma glucose concentration, red eyes (blood-shot), pale skin and impaired swimming. [ABSTRACT FROM AUTHOR]

It has been estimated that 44,000 Caretta caretta turtles die every year due to anthropomorphic activity in the Mediterranean Sea, and that longline fishing is one of the most significant causes of mortality. A total of 482 specimens of C. caretta were rescued from different parts of the Sicilian coast (Mediterranean Sea) from 2014 to 2016. The most numerous stranding was recorded during the spring and summer seasons, mainly along the north and eastern coasts of Sicily. The curved carapace length for all the specimens ranged from between 19 and 95 cm and most of these were young or sub adults. The highest number of strandings was recorded in 2014 and 2015, with 206 and 169 individuals, respectively. A total of 66 live specimens out of 239 were successfully rehabilitated and released after surgery or drug therapy; fishing hooks were found in 129 specimens in different parts of the digestive tract with greater frequency in the oesophagus (47.3%) followed by the gut (24.8%), stomach (14.7%), and mouth (13.2%). This paper will highlight the incidence of the incidental catch by longline fishing of C. caretta along the Sicilian coasts and also relate the size of ingested hooks to the size of examined specimens. [ABSTRACT FROM AUTHOR]

Over the past five decades, marine mammal interactions with fisheries have become a major human-wildlife conflict globally. The emergence of longline fishing is concomitant with the development of depredation-type interactions i.e., marine mammals feeding on fish caught on hooks. The killer whale (Orcinus orca) is one of the species most involved in depredation on longline fisheries. The issue was first reported in high latitudes but, with increasing expansion of this fishing method, other fisheries have begun to experience interactions. The present study investigated killer whale interactions with two geographically isolated blue-eye trevalla (Hyperoglyphe antarctica) fisheries operating in temperate waters off Amsterdam/St. Paul Islands (Indian Ocean) and south-eastern Australia. These two fisheries differ in the fishing technique used (vertical vs. demersal longlines), effort, catch, fleet size and fishing area size. Using 7-year (2010-16) long fishing and observation datasets, this study estimated the levels of killer whale interactions and examined the influence of spatio-temporal and operational variables on the probability of vessels to experience interactions. Killer whales interactions occurred during 58.4% and 21.2% of all fishing days, and over 94% and 47.4% of the fishing area for both fisheries, respectively. In south-eastern Australia, the probability of occurrence of killer whale interactions during fishing days varied seasonally with a decrease in spring, increased with the daily fishing effort and decreased with the distance travelled by the vessel between fishing days. In Amsterdam/St. Paul, this probability was only influenced by latitude, with an increase in the southern part of the area. Together, these findings document two previously unreported cases of high killer whale depredation, and provide insights on ways to avoid the issue. The study also emphasizes the need to further examine the local characteristics of fisheries and the ecology of local depredating killer whale populations in as important drivers of depredation. [ABSTRACT FROM AUTHOR]

Abstract: We conducted a meta‐analysis of literature reporting on the use of circle hooks and J‐hooks in pelagic longline fisheries. Our study included more data than previous meta‐analyses of the effects of hook type, due to both a larger number of relevant studies available in recent years and a more general modelling approach. Data from 42 empirical studies were analysed using a random effects model to compare the effects of circle hooks and J‐hooks on catch rate (43 species) and at‐vessel mortality (31 species) of target and bycatch species. Catch rates with circle hooks were greater for 11 species, including four tuna species, six shark species and one Istiophorid billfish. Catch rates on circle hooks were lower for seven species, including two Istiophorid billfishes and two species of sea turtle. At‐vessel mortality was significantly lower with circle hooks in 12 species, including three tuna species, three Istiophorid billfishes, swordfish (Xiphias gladius) and three shark species. No species had significantly greater at‐vessel mortality when captured with a circle hook rather than a J‐hook. While our general approach increased model variability compared to more detailed studies, results were consistent with trends identified in previous studies that compared the catch rates and at‐vessel mortality (between hook types) for a number of species. Our results suggest that circle hooks can be a promising tool to reduce mortality of some bycatch species in pelagic longline fisheries, although the effects depend on the species and the metric (catch rate or at‐vessel mortality), emphasizing the need for fishery‐specific data in conservation and management decisions. [ABSTRACT FROM AUTHOR]

Catch per unit effort (CPUE) is a widely used index of population abundance for informing stock assessments for the purpose of estimating population status and setting fishing policies. However, for CPUE to be an unbiased index, influences that are not related to population abundance (e.g., spatial variation in effort and temporal changes in gear efficiency) must be accounted for in analyses known as CPUE standardization. In longline fisheries, one important factor that can affect CPUE is the spacing between hooks (‘spacing effect’), which influences effective effort and has largely been ignored in previous analyses. Here, we use the Pacific halibut ( Hippoglossus stenolepis ) long-line fishery as a case study to explore the spacing effect. Both commercial and experimental (fishery-independent) data with hook spacing, and a survey-based CPUE series, are available for this fishery. It thus provides a unique opportunity to explore the effect of hook spacing and its effect on CPUE trends. We quantify this effect using non-parametric and parametric relationships inside a spatially-explicit (geospatial) CPUE standardization model for commercial data, and non-linear mixed-effects model for experimental data. We found a clear non-linear spacing effect (i.e., hooks were less effective the closer they were), but accounting for space had a larger effect on CPUE trends than accounting for hook spacing. For this stock, it is likely the effect of hook spacing on CPUE was minimal due to little variation in average hook spacing over time. Regardless, historical and future trends in hook spacing can have important effects on longline CPUE standardization, highlighting the value of collecting this information. Accounting for hook spacing effects in other fisheries may improve estimates of trends in relative abundance and lead to better management. [ABSTRACT FROM AUTHOR]

Improvement of harvesting efficiency and mitigation of undesirable environmental impacts of fishing gears are of considerable importance for achieving long term economic and environmental sustainability in fisheries. This paper analyses the operational efficiency and economic performance of the circle hook and the J-hook, commonly used by traditional fishers in the demersal longline fishery of the Sultanate of Oman. A longline experiment was conducted at three fishing locations at Masirah Island of Al-Sharqiyah Governorate. A total of 6,120 baited J-hooks and circle hooks were deployed over a 17-day period. The findings from this experimental research suggest that the overall performance (measured under various operational yardsticks such as hooking status and location, catch composition and quality, catching efficiency, and time and cost efficiency) of the circle hook is better than its counterpart. The results also indicate that the use of circle hooks has the potential to yield better financial returns. It is acknowledged that the reliance on three fishing locations may restrict the scientific generalizations. However, it is hoped that the results from this study will provide insight into the design of future experiments to ensure the validity of the present results and design effective management measures which will promote ecosystem-based approach to fishery management advocated by the FAO Code of Conduct for Responsible Fisheries. [ABSTRACT FROM AUTHOR]

In the Gulf of Alaska, sperm whales ( Physeter macrocephalus ) are known to remove sablefish ( Anoplopoma fimbria ) from commercial longline fishing gear. This removal, called depredation, is economically costly to fishermen, presents risk of injury or mortality to whales, and could lead to unknown removals during the federal sablefish longline survey that contributes to estimation of the annual fishing quota. In 2013 the Southeast Alaska Sperm Whale Avoidance Project (SEASWAP) evaluated the efficacy of an acoustic decoy in reducing encounters between sperm whales and longline fishing gear. The aim of the acoustic decoy was to use fishing vessel sounds to attract whales to an area away from the true fishing haul in order to reduce interactions between commercial fishing vessels and whales. A custom playback device that could be remotely activated via a radio modem was incorporated into an anchored buoy system that could be deployed by the vessel during a two-month trip between June and July 2013. Once activated, the decoy broadcasted vessel-hauling noises known to attract whales, while the vessel performed several true hauls at various ranges from the device. Passive acoustic recorders at both the decoy and true set locations were also deployed to evaluate whale presence. Twenty-six hauls were conducted while a decoy was deployed, yielding fourteen sets with whales present while the decoy was functional. A significant relationship was found between the number of whales present at the true fishing haul and the distance of the haul from the decoy (1–14 km range), with the decoy being most effective at ranges greater than 9 km ( t = −2.06, df = 12, p = 0.04). The results suggest that acoustic decoys may be a cost-effective means for reducing longlining depredation from sperm and possibly killer whales under certain circumstances. [ABSTRACT FROM AUTHOR]

Fisheries impacts on marine megafauna have received global attention and are recognized as a serious problem. In Saudi waters of the Arabian Gulf, the artisanal fishery is responsible for 99.6% of landings. It uses a range of boat sizes and various types of fishing gears and operates in all accessible areas from shallow coastal bays to deep offshore waters. The objective of this work is to assess the captures and the impact of all fishing gear types used by the Saudi artisanal fishery on four marine megafauna groups: turtles, birds, dolphins, and dugongs ( Dugong dugon ). Nine questionnaire surveys were carried out from May 2013 to November 2014, covering a two-month period each. Ten main gear types were found to be used by 25 directed fisheries, including shrimp trawl, wire trap, hand line, troll, pelagic and demersal longline, and drift, surrounding, fixed, and set gillnets. Turtles were captured in relatively high numbers (4726 captures year −1 ) in nine directed fisheries, among which shrimp trawl fishery was responsible for 86.3% of the captures. The lowest capture rates were found with birds (13.1 captures year −1 ) and dolphins (7.4 captures year −1 ), related mainly with the Spanish mackerel longline and Indian mackerel surrounding gillnet fisheries. No dugong captures were recorded. In all, the Saudi artisanal fishery operating in the Arabian Gulf has a high impact on turtles and low impact on birds and dolphins. No impact on dugongs was reported during this study. [ABSTRACT FROM AUTHOR]

Bird scaring lines (BSLs) protect longline fishing gear from seabird attacks, save bait, reduce incidental seabird mortality and are the most commonly prescribed seabird bycatch mitigation measure worldwide. We collaborated with fishermen to assess the efficacy of applying BSL regulations from the demersal longline sablefish fishery in Alaska to a similar fishery along the U.S West Coast. In contrast to Alaska, some U.S. West Coast vessels use floats along the line to keep hooks off the seafloor, where scavengers degrade the bait and the target catch. Our results confirmed that BSL regulations from Alaska were sufficient to protect baits from bird attacks on longlines without floats, but not baits on longlines with floats. Longlines with floats sank below the reach of albatrosses (2 m depth) at a distance astern (157.7 m ± 44.8 95% CI) that was 2.3 times farther than longlines without floats (68.8 m ± 37.8 95% CI). The floated longline distance was well beyond the protection afforded by BSLs, which is approximately 40 m of aerial extent. Black-footed albatross attacked floated longlines at rates ten times more (2.7 attacks/1000 hooks, 0.48–4.45 95%CI) than longlines without floats (0.20 attacks/1000 hooks, 0.01–0.36 95% CI). Retrospective analysis of NOAA Fisheries Groundfish Observer Program data suggested that seabird bycatch occurs in a few sablefish longline fishing sectors and a minority of vessels, but is not confined to larger vessels. Analysis also confirmed fishermen testimonials that night setting reduced albatross bycatch by an order of magnitude compared to daytime setting, without reducing target catch. Night setting could be an effective albatross bycatch prevention practice if applied to the U.S. West Coast sablefish longline fishery and provide a practical alternative for vessels that elect to use floated longlines. These results highlight the importance of understanding region-specific longline gear modifications to identify effective bycatch reduction tools and the value of working collaboratively with fishermen to craft solutions. [ABSTRACT FROM AUTHOR]

We investigated the effects of hook soak time on targeted reef species and shark bycatch in the reef fish bottom longline fishery in the Gulf of Mexico. Beginning in 2010, capture time and catch per unit effort (CPUE) for the primary target species red grouper ( Epinephelus morio ) in the fishery were evaluated using hook timers. Findings indicated that typical duration of hook soak times is longer than necessary to efficiently harvest red grouper and a reduction in gear soak times to less than one hour would result in minimal or no reduction in red grouper CPUE. The mean capture time of sharks and red grouper differed significantly, suggesting that a reduction in soak time would likely reduce the bycatch of sharks in the fishery. The study also revealed barometric pressure, lunar phase, and fish size were significant covariates with red grouper capture times and that different bait types significantly affected CPUE. Implementing shorter hook soak times would likely improve fishery profitability and potentially reduce discards of unwanted species in the fishery. [ABSTRACT FROM AUTHOR]

The pattern of somatic growth of the Pacific oyster Crassostrea gigas cultured in suspension in Geoje-Hansan Bay, Korea was evaluated between July 2013 and March 2014 comparing culturing sites and depths. Gross biochemical composition of oyster tissues provided a measure of physiological status, and clearance rates of oysters provided a measure of feeding physiology at different water flow speeds. A growth curve model indicated greater tissue growth in the surface than in the bottom layers, and advanced summer growth by more than 4 months in the stagnant inner bay compared with winter growth in the more rapidly flowing outer bay. Our results suggest that rapid tissue growth of oysters in the surface layer in summer is supported by high primary productivity in the inner bay. In contrast, oyster growth performance at the outer bay in late fall and winter may be related to seasonal food availability that is regulated by short residence time and thereby rapid renewal of water compared to the inner bay. Furthermore, a combination of the water flow regime of the bay and the flow rate-dependent feeding physiology of oysters proved to be an important determinant of seasonal growth dynamics. Finally, oyster growth was better explained by water flow rates than by hydrographic conditions. [ABSTRACT FROM AUTHOR]

Longline fishing kills over 160,000 seabirds annually, with bycatch in these fisheries contributing significantly to the widespread, global decline in albatross populations. One of the most effective ways to reduce this bycatch is for pelagic longliners to set their hooks entirely at night, when albatross are least active, and setting at night is recommended in some areas of the ocean by Regional Fisheries Management Organizations. To develop a global dataset of where and when longliners actually set their hooks, we apply machine learning to four years of GPS data of the global longline fleet (~5000 vessels). Our data reveal the vast footprint of longline fishing: over 40 % of the ocean is, at least one time during a year, within 30 km of a set, the distance within which an albatross can detect a vessel. On a given day, about 1.5 % of the ocean is within this distance of a set. Almost all of these sets were during daylight hours, with only 3 % of sets occurring entirely at night. In regions with threatened albatross species, night setting is more common (4–9 %), but it is much lower than suggested by on-board observer programs, highlighting the limitations of current monitoring. Furthermore, in albatross habitat, vessels more often set their lines during dawn hours when these birds are most active and bycatch risk is highest. [ABSTRACT FROM AUTHOR]

In 2000, longline fishing was banned inside the Galapagos Marine Reserve to prevent illegal fishing of sharks and bycatch of endangered, threatened, and protected (ETP) species. Despite local management institutions possess one of the most sophisticated control and surveillance systems in the Eastern Tropical Central Pacific, statistical and anecdotic evidence suggest the longline ban has been ineffective in eradicating illegal, unreported and unregulated (IUU) fishing for the last two decades. This short communication examines the legal, institutional, and socio-economic factors that have prevented the effective implementation of the longline ban and proposes an ecosystem approach to fisheries to maintain bycatch mortality rates below biologically based limits, facilitating the recovery of ETP species while safeguarding a sustainable development of the Galapagos small-scale tuna fishery. Significant investments in science, technology, and innovation are necessary to encourage gradual and adaptive improvements in fishing practices to reduce IUU fishing and bycatch. [ABSTRACT FROM AUTHOR]

Capture of sea turtles in longline fisheries has been implicated in population declines of loggerhead (Caretta caretta) and leatherback (Dermochelys coriacea) turtles. Since 2004, United States (U.S.) longline vessels targeting swordfish and tunas in the Pacific and regions in the Atlantic Ocean have operated under extensive fisheries regulations to reduce the capture and mortality of endangered and threatened sea turtles. We analyzed 20+ years of longline observer data from both ocean basins during periods before and after the regulations to assess the effectiveness of the regulations. Using generalized additive mixed models (GAMMs), we investigated relationships between the probability of expected turtle interactions and operational components such as fishing location, hook type, bait type, sea surface temperature, and use of light sticks. GAMMs identified a two to three-fold lower probability of expected capture of loggerhead and leatherback turtle bycatch in the Atlantic and Pacific when circle hooks are used (vs. J hook). Use of fish bait (vs. squid) was also found to significantly reduce the capture probability of loggerheads in both ocean basins, and for leatherbacks in the Atlantic only. Capture probabilities are lowest when using a combination of circle hook and fish bait. Influences of light sticks, hook depth, geographic location, and sea surface temperature are discussed specific to species and regions. Results confirmed that in two U.S.-managed longline fisheries, rates of sea turtle bycatch significantly declined after the regulations. In the Atlantic (all regions), rates declined by 40 and 61% for leatherback and loggerhead turtles, respectively, after the regulations. Within the NED area alone, where additional restrictions include a large circle hook (18/0) and limited use of squid bait, rates declined by 64 and 55% for leatherback and loggerhead turtles, respectively. Gains were even more pronounced for the Pacific shallow set fishery, where mean bycatch rates declined by 84 and 95%, for leatherback and loggerhead turtles, respectively, for the post-regulation period. Similar management approaches could be used within regional fisheries management organizations to reduce capture of sea turtles and to promote sustainable fisheries on a global scale.

Industrial longline fisheries cause the death of large numbers of seabirds annually. Various mitigation measures have been proposed, including the use of tori lines. In this study the efficiency of a single tori line to reduce seabird bycatch was tested on pelagic longline vessels (25-37m length). Thirteen fishing trips were carried out in the area and season of the highest bycatch rates recorded in the southwest Atlantic (2009–2011). We deployed two treatments in random order: sets with a tori line and without a tori line (control treatment). The use of a tori line significantly reduced seabird bycatch rates. Forty three and seven birds were captured in the control (0.85 birds/1,000 hooks, n = 49 sets) and in the tori line treatment (0.13 birds/1,000 hooks, n = 51 sets), respectively. In 47% of the latter sets the tori line broke either because of entanglement with the longline gear or by tension. This diminished the tori line effectiveness; five of the seven captures during sets where a tori line was deployed were following ruptures. Nine additional trips were conducted with a tori line that was modified to reduce entanglements (2012–2016). Seven entanglements were recorded in 73 longline sets. The chance of a rupture on these trips was 4% (95% c.l. = 1–18%) of that during 2009–2011. This work shows that the use of a tori line reduces seabird bycatch in pelagic longline fisheries and is a practice suitable for medium size vessels (~25-40m length). Because the study area has historically very high bycatch rates at global level, this tori line design is potentially useful to reduce seabird bycatch in many medium size pelagic longline vessel fishing in the southern hemisphere. [ABSTRACT FROM AUTHOR]

Mortality during commercial fishing activities is a significant threat to many imperiled seabird species, and myriad technologies have been developed to reduce mortality during longline fishing operations. However, individual studies have never been combined in a quantitative manner to determine if seabird bycatch reduction devices (BRD) have a detrimental effect upon target species catch. We performed a meta-analysis of the longline fishery BRD literature to determine the general impact of BRD technology upon commercial fishing operations. There were relatively few papers with data suitable for a meta-analysis (15), therefore we pooled studies in the analysis with BRD and fishery related metrics included as covariates. Overall, we found no reduction in target fish catch. In fact, we found an increase in target catch of 9% (95% CI [1,17]) with BRD use. We show that this increase occurs while BRDs reduce seabird bycatch by 89% (95% CI [82,93]). These patterns do not change with respect to geographic location or BRD type, indicating that efforts to reduce seabird bycatch are generally effective under different conditions. Our review identifies research needed to ensure the generality of our findings and to better understand the impacts of BRD implementation upon seabird conservation and commercial fisheries. [ABSTRACT FROM AUTHOR]

Seabirds, as foragers in marine waters for at least part of their lifecycle, encounter the global fishing fleet in search of marine resources. While fishing gear is designed to catch fish and invertebrates, it also catches unintended species, including seabirds. We reviewed bycatch incidence for 378 marine and coastal bird species in 18 different gear types, and found that 60% (228 species) have been recorded interacting with at least one type of fishing gear. At least one species from each of the taxonomic groups analyzed (generally at the family level) has been documented interacting with fishing gear. With respect to two measures of degree of interaction, four families have a high degree of documented interaction: Gaviidae (loons or divers), Podicipedidae (grebes), Diomedeidae (albatrosses) and Sulidae (boobies and gannets). Set and drift gillnets (among the most studied gear types), have the greatest number of documented species interactions: 92 and 88 species, respectively. Hook gear (longlines and handlines) have documented interactions with 127 species. Together these four gear types have documented bycatch of 193 species. The waters of the Arctic, the Caribbean, the Guinea and Canary Currents in the Atlantic, the Indian Ocean and Asia have been poorly studied. Particular gear types, including industrially-deployed seines, and the artisanal fisheries sector also constitute significant gaps in our knowledge of seabird bycatch patterns worldwide. [ABSTRACT FROM AUTHOR]