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The archipelago of the Azores (mid-north Atlantic Ocean) is an outermost region of the European Union (EU) in which small-scale fisheries are a strong component of the local economy. Bottom longlining and handlining are the most important Azorean fisheries in landing values, fishing vessels and fishers. Despite their high selectivity and low discards, these fisheries can be highly impacted by the implementation of the Landing Obligation (LO). Semi-structured interviews were conducted with Azorean small-scale fishers to document their perceptions about discards and the LO, and to ascertain the mitigation measures they already implement or could further implement to avoid unwanted catch. Results suggest that most fishers strongly oppose the LO, perceiving it as inadequate to their fisheries. Several discard avoidance measures are already commonly used by most fishers, of which hook size and changing areas where there are too many undersized or over-quota individuals, are believed to be the most efficient. Additional measures to further improve selectivity and avoid unwanted catch appear limited. The recent conversion of many bottom longliners to handlining and the exemptions foreseen as part of the LO for the region might help Azorean fishers to mitigate the potential impacts of the LO., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Effective ocean management and the conservation of highly migratory species depend on resolving the overlap between animal movements and distributions, and fishing effort. However, this information is lacking at a global scale. Here we show, using a big-data approach that combines satellite-tracked movements of pelagic sharks and global fishing fleets, that 24% of the mean monthly space used by sharks falls under the footprint of pelagic longline fisheries. Space-use hotspots of commercially valuable sharks and of internationally protected species had the highest overlap with longlines (up to 76% and 64%, respectively), and were also associated with significant increases in fishing effort. We conclude that pelagic sharks have limited spatial refuge from current levels of fishing effort in marine areas beyond national jurisdictions (the high seas). Our results demonstrate an urgent need for conservation and management measures at high-seas hotspots of shark space use, and highlight the potential of simultaneous satellite surveillance of megafauna and fishers as a tool for near-real-time, dynamic management.

Background: The meagre, Argyrosomus regius, is a large coastal predatory fish inhabiting waters from the north-eastern Atlantic and Mediterranean Sea, where it is targeted by commercial and recreational fisheries. Previous genetic studies have found an unexpectedly high population differentiation not only between the Atlantic and the Mediterranean, but also along the Atlantic coast. However, the reasons underpinning this genetic barrier remained unclear. Likewise, even though the species is amongst the world's largest marine teleosts, knowledge about its movement ecology and migratory behaviour remains notably scarce, and primarily reliant on fisheries-dependent data. Methods: In this study, we used a combination of acoustic telemetry and pop-up satellite archival tags to investigate the movements of 22 adult meagre (70–143 cm total length) along the Southwestern coast of the Iberian Peninsula. Results: Our results strongly suggest that the previously reported genetic differentiation is not maintained by limited adult dispersal/movement, as hypothesized. On the contrary, we documented some of the longest individual annual migrations ever recorded for a coastal teleost, up to > 2000 km, with frequent back-and-forth movements between the West and Southern Iberian coasts. Moreover, their detected regional movement patterns support the existence of a marked seasonal behavioural shift, with individuals being less active and moving to deeper waters during winter, and are consistent with spawning philopatry associated to their summer reproductive movements. Finally, we identified putative aggregation areas that may harbour important feeding/overwintering grounds. Conclusions: These findings shed new light on the movement and behaviour patterns of meagre that may be of particular importance for the conservation and spatial management of this species throughout its range, and open the door to further research on functional connectivity. [ABSTRACT FROM AUTHOR]

Argyrosomus regius (commonly referred to as meagre), is one of Europe's largest coastal bony fish species and supports important recreational and commercial fisheries in the Atlantic and Mediterranean coasts. Demand for this species, and more recently for their swim bladders, has led to regional population declines and growing importance as an aquaculture species. Despite intense research in captivity, little is known about the spatial ecology of A. regius's wild population, including basic information such as vertical migrations and depth/temperature preferences. Previous research based on indirect data suggests a seasonal habitat shift from shallow to deeper waters, but this has never been validated through direct high-resolution movement data. In this study, we tagged 13 adult A. regius with pop-up satellite archival tags in the South of Portugal, which successfully returned data from 11 individuals including high-resolution data from six recovered tags (mean, range: 167 days, 28–301 days). We found that adults of this population spend 95.2% of their time between 5 and 75 m depth (mean ± SD, 30.9m ± 18.3m) and do not venture beyond 125 m. Across seasons, A. regius move across water temperatures between 13.3 and 24.8°C with a preferred thermal range between 14 and 18°C where they spent 75.4% of their time. The inferential modelling using this electronic data validated previous hypotheses by showing significant differences between a shallower and warmer summer habitat vs. a deeper and cooler winter habitat. Visual investigation of the diel effects on depth preferences suggests subtle changes in depth use between day and night during the warmer months of the year. We speculate that these patterns are in response to the species' behavioural ecology and physiology, reflecting the seasonal changes in water stratification and presence of prey, as well as on the species reproduction, which results in summer spawning aggregations in shallower areas. [ABSTRACT FROM AUTHOR]

Deep-water sharks are highly diverse, vulnerable, and understudied as a group, despite the increasing pressures on their populations. Twenty-five species of deep-water sharks have been recorded in the Azores, an oceanic archipelago in the mid-North Atlantic, that are regularly caught as bycatch in hook-and-line fisheries. Avoiding the bycatch of deep-water sharks presents multiple challenges due to their high catchability, difficulties in correctly identifying species, and the general lack of data on these species. This review summarizes the findings of recent studies from the region, providing an up-to-date science-based framework for mitigating bycatch effects of Azorean hook-and-line fisheries. Several depth-based, area-based, and gear-based measures have been studied that demonstrate the potential to either avoid or increase the survival of deep-water shark bycatch. However, these measures may have limited efficacy for some species (e.g. highly mobile species) and thus, limited widespread applicability. Convincing fishers to avoid deep-water shark bycatch is also a challenge given the antagonistic interactions with sharks damaging the catch and fishing gear, while simultaneously a market incentive for shark liver oil remains. It highlights the need to proactively engage fishers and incentivize the mitigation of bycatch of deep-water sharks in Azorean waters. [ABSTRACT FROM AUTHOR]

Broadbill swordfish (Xiphias gladius) is a key species in commercial fisheries, but management efforts continue to be hindered by data gaps in their basic biology, including ongoing debate over stock boundaries and movement between management zones. We deployed 20 pop-up satellite archival transmitting (PSAT) tags on juvenile swordfish in the Azores and adults in the northwest Atlantic (NWA). We applied a recently developed geolocation approach that synthesizes tag data with a global observation-assimilating ocean model to improve geolocation accuracy. Resulting tracks from 16 individuals averaged 3751 km (range 345–7247 km) over 93 days (range 17–181 days). Juveniles tagged in the Azores made regional movements while adults tagged in the NWA moved between summer foraging grounds near the Grand Banks to winter habitats near the Antillean Arc. All individuals spent considerable time in the mesopelagic zone during the day, and this behaviour increased with fish size. We integrate results from our PSAT-based movements with conventional tag and catch-per-unit effort data, which indicates complex stock structure within the North Atlantic that largely supports current stock boundaries. Our work demonstrates the utility in synthesizing fishery-independent electronic tag data and fisheries datasets to improve our understanding of large pelagic fish ecology. [ABSTRACT FROM AUTHOR]

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Abstract: Marine reserves have been widely implemented as tools for biodiversity conservation and fisheries management, amongst other goals. A large number of empirical studies have focused on their effects on reef fish populations. Yet, few studies have looked at their effectiveness on semelparous species such as cephalopods, in spite of their commercial importance in many coastal regions across the globe. In this study we combine behavioural (biotelemetry) and demographic (experimental fishing) data to understand the effects of the Luiz Saldanha Marine Park (LSMP) on local populations of cuttlefish, Sepia officinalis. We used a beyond-BACI design to analyze the possible effect of the implementation of a no-take area on the abundance and biomass of this species and acoustic telemetry data to assess its site fidelity and movements within the study area. Results indicate that there was no detectable effect of the implementation of the no-take area on the abundance or biomass of cuttlefish. We found evidence that acoustically tagged adult cuttlefish leave the reserve a few days or weeks after tagging. The fact that cuttlefish have low site fidelity inside the reserve and large movements across and beyond the study area explains why there is no increase in the population inside the MPA. These results suggest that small coastal marine reserves such as the LSMP are not effective in providing long term protection to cuttlefish populations and, probably, those of other short-lived, highly mobile cephalopods. [Copyright &y& Elsevier]

Abstract: A 10-year bottom longline survey and a smaller scale hook-and-line survey were used to study how habitat and fishing might affect the population structure of red porgy (Pagrus pagrus) at various scales in the archipelago of the Azores, central north Atlantic. The size and sex of fish caught responded to local factors rather than fishing or larger scale (geographic) factors. Young-of-the-year red porgy recruit to shallow, sandy habitats located inshore, and apparently migrate toward deeper and progressively rockier bottoms. This pattern seems to explain why red porgy are only found around the islands’ shores, being absent from shallow seamounts where suitable adult habitat exists but juvenile habitat is absent. The probability of sex-change was higher in sites whenever abundance was low. Significant large-scale differences among islands may well be attributable to exploitation, as the lowest abundances were consistently found off islands subject to higher fishing efforts. We also found some evidence of positive effects on porgy abundance and biomass from a 4-year ban on inshore longline fishing, but such benefits lack further (temporal) evidence. Recruitment to the fishery varied twice by an order of magnitude during the 10-year longline monitoring period, reflecting also high natural variability. These findings highlight the need to explicitly include the habitat essential for growth and, eventually, the presence of adequate ontogenic migration corridors when devising schemes of spatial management of red porgy populations, including marine reserves. [Copyright &y& Elsevier]

Copyright of Arquipélago. Life & Marine Sciences / Ciencias Biológicas e Marinhas is the property of Universidade dos Acores 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.)

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]

The recognition that deep-water sharks are among the most vulnerable marine species to fisheries exploitation led to the implementation of fishing prohibition regulations in European waters. Reducing unwanted bycatch and mortality are key fisheries mitigation measure for the conservation of these species. Yet, few studies have investigated how to mitigate the common bycatch of these sharks on deep-water longline fisheries. Specifically, the potential of hook type as such a measure has never been investigated. Here, we conducted fishing experiments to test how circle hooks affect the catchability, the hooking position, and the overall condition of deep-water sharks, in comparison to the commonly used J-hooks in the Azores bottom longline fishery. We found that circle hooks did not significantly reduce deep hooking (throat or gut hooked), nor improve the overall condition of captured sharks, while the catchability of deep-water sharks on circle hooks was greater than on the J-hooks currently used in the local fishery. As such, circle hooks do not appear as a suitable measure to reduce deep-water shark bycatch and increase survival potential in deep-water longlining. Despite deep hooking being rare for the deep-water sharks caught with both hook types in the experiments, at-vessel mortality was still substantial (around 40%). Post-release survival remains mostly unquantified but preliminary results suggest it could also be high. This study highlights the urgent need for continued research addressing bycatch mitigation measures for deep-water sharks and identifying efficient strategies to reduce bycatch and increase survival. • We tested circle hook as potential bycatch mitigation measure for deep-water sharks. • Circle hooks resulted in higher catch of deep-water sharks than J-hooks. • Circle hooks did not reduce deep hooking nor improve deep-water shark condition. • Circle hooks did not appear suited to mitigate deep-water shark bycatch in longlines. • Alternative measures to reduce bycatch and improve survival are still much needed. [ABSTRACT FROM AUTHOR]

Abstract: In the North Atlantic, blue shark has become an important by-catch species for the pelagic swordfish fisheries, and even the target species of these fisheries when swordfish abundance is low. Still, their complex life cycle and population structure remain poorly understood, limiting current management and conservation efforts for this species. This study provides information on the population structure and seasonal abundance of blue shark around the Azores Archipelago, in the central North Atlantic, based on detailed analyses of fishery independent and observer data for the area. A total of 23,119 blue sharks were sampled during 388 research longline fishing sets conducted between 1993 and 2004. Standardised catch rates varied greatly over the year, reflecting the changing presence of different sex and life stages in the area, and were strongly influenced by environmental factors, namely sea surface temperature, sea surface height anomalies and lunar cycle. In general, the catches were strongly dominated by juveniles, with higher catch rates during winter months. Young-of-the-year (YOY) juveniles of both sexes were present throughout the year. While older juvenile and sub-adult females dominated during winter, juvenile males dominated during the rest of the year, indicating that different juvenile life stages of both sexes alternate in using the area. The presence of mature females in advanced stages of pregnancy during spring, and the appearance of the smallest size-classes of YOY in early summer also suggest that the area is used as a pupping ground. Mature males appear mainly during summer, probably for feeding. The periodic presence of all these life stages emphasises the central role of the area, as some of these population components are seasonally associated with one of either sides of the North Atlantic. [Copyright &y& Elsevier]

The Azores (mid-north Atlantic) has a long history of artisanal multispecific fishery exploiting marine resources around the islands slopes and seamounts. Due to the archipelago´s oceanic character, demersal-deep-sea and pelagic-offshore species are central to local economy. However, a coastal subsistence fishery is also economically and culturally important, as well as understudied, underregulated and, up to the present, lacking independent monitoring. A Productivity and Susceptibility Analysis (PSA) was applied to determine stock vulnerability of 38, criteriously selected, coastal species. The PSA identified 20 stocks of concern (3 of which at major risk), thus considered of (high) priority to benefit from a precautionary management approach, at least until more quantitative stock assessments are developed in the future. All of these species generally share (1) a considerable basic knowledge gap (e.g., demography, trophic links, reproduction, habitat use, fisheries); and (2) the absence of previous formal stock assessments, resulting in unknown current population status. Such gaps become graver considering that most of these coastal resources show patterns consistent with progressive signs of intensive or even overexploitation, due to the intensification of combined pressure from the commercial and recreational coastal fishing dating back as early as the 1980's. As such, we propose an ecosystem-based framework for the regular monitoring, assessment and guidelines for general management of these data-poor coastal resources and fisheries in the region. [ABSTRACT FROM AUTHOR]