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Although bycatch of seabirds and other long-lived species is a critical conservation issue in world fisheries, case studies documenting significant reductions in the mortality of these low-productivity species in a fishery are rare. We studied progress toward seabird conservation in the Alaskan longline fisheries, one of the largest and most diverse demersal fisheries. We generated annual seabird bycatch rates in 4 target fisheries and all fisheries combined from 23 years of fisheries observer data. We used 0-inflated negative binomial models to evaluate variables influencing seabird bycatch per unit effort (BPUE) in 2 target fisheries. Following adoption of streamer lines, at first voluntarily and then mandatorily, seabird BPUE was reduced by 77–90%, preventing mortality of thousands of birds per year. Despite this, BPUE increased significantly in 2 of 4 target fisheries since streamer lines were adopted. Although night setting yielded significant reductions (74–97%) in seabird BPUE and significant increases (7–11%) in fish catch per unit effort over daytime setting, nighttime setting increased the BPUE of Northern Fulmar (Fulmarus glacialis) by 40% and nontarget fish species by 5–17%. Thus, best practices to prevent seabird mortalities in longline fisheries varied by species assemblage and fishery. Our results inform global efforts toward fisheries bycatch reduction by illustrating that successful conservation requires fishery-specific solutions, strong industry support, constant vigilance in analysis and reporting observer data, and ongoing outreach to fleets, especially to vessels with anomalously high BPUE. Aunque la captura accesoria de aves marinas y otras especies con ciclos de vida largos es un asunto de importancia para la conservación en las pesquerías a nivel global, son raros los estudios de caso que documentan las reducciones significativas de la mortalidad de estas especies de baja productividad en las pesquerías. Estudiamos el progreso hacia la conservación de aves marinas en las pesquerías con palangre en Alaska, una de las pesquerías demersales más grandes y con mayor diversidad. Generamos tasas anuales de capturas accesorias de aves marinas para cuatro pesquerías y todas las pesquerías combinadas a partir de 23 años de datos de observación de pesquerías. Usamos modelos binomiales negativos con inflación 0 para evaluar las variables que influyen sobre la captura accesoria de aves marinas por unidad de esfuerzo (BPUE, en tnglés) en dos pesquerías. Después de la adopción de la caña de pescar, al principio voluntariamente y después de manera obligatoria, el BPUE de aves marinas se redujo entre un 77 y 90%, lo que previno la mortalidad de miles de aves por año. A pesar de esto, el BPUE incrementó significativamente en dos de las cuatro pesquerías diana desde que se adoptaron las cañas de pescar. Aunque las puestas nocturnas resultaron en reducciones significativas (74-97%) en el BPUE de aves marinas e incrementos significativos (7-11%) en la captura de peces por unidad de esfuerzo comparadas con las puestas diurnas, las puestas nocturnas incrementaron el BPUE del fulmar boreal (Fulmarus glacialis) en un 40% y entre un 5 y 17% el de las especies de peces cuya captura no es relevante para las pesquerías. Por lo tanto, las mejores prácticas para prevenir la mortalidad de las aves marinas en las pesquerías con palangre variaron dependiendo del grupo de especies y de la pesquería. Nuestros resultados informan a los esfuerzos globales hacia la reducción de la captura accesoria de las pesquerías al ilustrar que la conservación exitosa requiere de soluciones específicas por pesquería, un fuerte apoyo por parte de la industria, una vigilancia constante del análisis y el reporte de los datos de observación, y una participación continua de las flotas, especialmente en el caso de navíos con un BPUE anormalmente alto. 尽管全世界的渔场都面临着海鸟和其它寿命长的物种遭到兼捕这样ー个重要保护向题，但关于渔场中这 些低繁殖率物种的死亡率显著下降的案例分析仍然狼少。本研究分析了規模最大、种类最多的底层渔场之一 的阿拉斯加延绳钓渔场在海鸟保护方面的进展。我们根据 23 年间渔场的观察数据，获得了四个目标渔场和所 有渔场整体上毎年海鸟兼捕率的数据，并用零膨张负ニ项模型估计了两个目标渔场中影响每单位工作量的海鸟 兼捕量(bycatch per unit effort, BPUE)的因素。在从自愿到强制性地采用了飞绳钓方法之后，海鸟BPUE減 少了77-90%，毎年防止了数千只鸟的死亡。尽管如此，采用飞绳钓后，四个目标渔场中还是有两个渔场BPUE 显著增加。虽然夜间放钓竿相比于日间放钓竿，海鸟BPUE显著减少(74-97%),且每单位工作量的渔获量显著 増加77-11%),担夜间放钓竿导致暴雪鹱(Fulmarus glacialis；的BPUE増加了40%，非目标鱼种的BPUE也增加 T5-17%o因此，防止延绳钓渔场中海鸟死亡的最佳实践取决于物种群落和渔场的具体情况。我们的结果阐明 了成功的保护需要针对各个渔场_ 定解决方案、有强有力的产业支持、对观察数据的分析和报告保持谨慎，以 及要注意不断扩大的船队，特别是引起异常高BPUE的船只。这些结果为全球渔场减少兼捕的努力提供了重要 信息。

In the current study, remotely sensed sea surface ocean temperature (SST) and sea surface chlorophyll (SSC), an indicator of tuna abundance, were used to determine the optimal feeding habitat zone of the southern Indian Ocean (SIO) albacore using a habitat suitability model applied to the 2000–2016 Taiwanese longline fishery data. The analysis showed a stronger correlation between the 2-month lag SSC and standardized catch per unit effort (CPUE) than 0-, 1-, 3-, and 4-month lag SSC. SST also exhibited a stronger correlation with standardized CPUE. Therefore, SST and SSC_2 were selected as final variables for model construction. An arithmetic mean model with SST and SSC_2 was deemed suitable to predict the albacore feeding habitat zone in the SIO. The preferred ranges of SSC_2 and SST for the feeding habitat of immature albacore were 0.07–0.09 mg m−3 and 16.5–18.5 °C, respectively, and mainly centralized at 17.5 °C SST and 0.08 mg m−3 SSC_2. The selected habitat suitability index model displayed a high correlation (R2 = 0.8276) with standardized CPUE. Overall, temperature and ocean chlorophyll were found to be essential for albacore habitat formation in the SIO, consistent with previous studies. The results of this study can contribute to ecosystem-based fisheries management in the SIO by providing insights into the habitat preference of immature albacore tuna in the SIO.

False killer whales (Pseudorca crassidens) depredate bait and catch in the Hawai‘i‐based deep‐set longline fishery, and as a result, this species is hooked or entangled more than any other cetacean in this fishery. We analyzed data collected by fisheries observers and from satellite‐linked transmitters deployed on false killer whales to identify patterns of odontocete depredation that could help fishermen avoid overlap with whales. Odontocete depredation was observed on ˜6% of deep‐set hauls across the fleet from 2004 to 2018. Model outcomes from binomial GAMMs suggested coarse patterns, for example, higher rates of depredation in winter, at lower latitudes, and with higher fishing effort. However, explanatory power was low, and no covariates were identified that could be used in a predictive context. The best indicator of depredation was the occurrence of depredation on a previous set of the same vessel. We identified spatiotemporal scales of this repeat depredation to provide guidance to fishermen on how far to move or how long to wait to reduce the probability of repeated interactions. The risk of depredation decreased with both space and time from a previous occurrence, with the greatest benefits achieved by moving ˜400 km or waiting ˜9 d, which reduced the occurrence of depredation from 18% to 9% (a 50% reduction). Fishermen moved a median 46 km and waited 4.7 h following an observed depredation interaction, which our analysis suggests is unlikely to lead to large reductions in risk. Satellite‐tagged pelagic false killer whales moved up to 75 km in 4 h and 335 km in 24 h, suggesting that they can likely keep pace with longline vessels for at least four hours and likely longer. We recommend fishermen avoid areas of known depredation or bycatch by moving as far and as quickly as practical, especially within a day or two of the depredation or bycatch event. We also encourage captains to communicate depredation and bycatch occurrence to enable other vessels to similarly avoid high‐risk areas.

Decision strategies in fisheries management are often directed by the geographic distribution and habitat preferences of target species. This study used remote sensing data to identify the optimal feeding habitat of albacore tuna in the Southern Atlantic Ocean (SAO) using an empirical habitat suitability model applying longline fisheries data during 2009–2015. An arithmetic mean model with sea surface temperature (SST) and sea surface chlorophyll-a concentration (SSC) was determined to be suitable for defining the albacore habitat in the SAO. The optimal ranges of SST and SSC for the habitat were approximately 16.5 °C–19.5 °C and 0.11–0.33 mg/m3, respectively. The study revealed a considerable positive trend between the suitable habitat area and standardized catch per unit effort (r = 0.97; p < 0.05); due to the west-to-east and northward development of the suitable habitat, albacore schools moved to the northeast of the SAO, thus increasing catch probability in April to August in that region. Overall, the frontal structure of SST and SSC plays an essential role in the formation of potential albacore habitats in the SAO. Our findings could contribute to the establishment of regional ecosystem-based fisheries management in the SAO.

Objective The Gulf of Mexico (GOM) reef bottom longline fishery typically not only targets groupers and snappers but also interacts with 27 species of sharks, which are primarily discarded as bycatch. Slow growth, late maturity, and low fecundity in a landscape of increasing fishing pressure make sharks comparatively more susceptible to overfishing and endangered status than other fishes. The purpose of this study was to determine which gear and/or environmental variables best predict the shark catch per set for commonly caught shark species in the GOM reef bottom longline fishery. Methods We considered 12 commonly caught shark species that vary from the abundant Atlantic Sharpnose Shark Rhizoprionodon terraenovae to the critically endangered Scalloped Hammerhead Sphyrna lewini. Catch per set, effort, gear, and environmental data were taken from the National Oceanic and Atmospheric Administration National Marine Fisheries Service observer dataset for the GOM reef bottom longline fishery (2009–2017) and were used to fit generalized additive models. The Bayesian information criterion and 10‐fold cross‐validation were used to select the best set of variables that predicted catch per set to determine gear configurations, fisher activities, and environmental conditions contributing to higher shark catch per unit effort. We modeled each species individually, all species combined, and species grouped by similar ecology. Result Gear and fishing method variables were consistently included in the best predictive models across species and were the only potential basis for a single strategy that could decrease bycatch across all 12 species. Patterns of environmental variables were only consistent across species with similar ecology and habitat. Conclusion Sharks as a group should not be lumped together, as the effects of mitigation measures become confounded and directly managing trade‐offs between species when minimizing bycatch becomes impossible. Focusing on gear rather than environmental variables is the best apparent option to potentially reduce shark catch per set across commonly caught species while minimizing trade‐offs. Impact statement Sharks are slow‐growing species that give birth to very few offspring late in life, making them highly susceptible to overfishing. We used catch data from the Gulf of Mexico to determine gear and environmental conditions that contribute to high shark catch in an attempt to minimize incidental shark catch and prevent overfishing. Focusing on gear configurations is the best apparent option to potentially reduce shark incidental catch across commonly caught species.

Pelagic longline fisheries worldwide incidentally take long-lived seabird species. This mortality has led to fisheries restrictions to protect seabirds at risk, including Wandering (Diomedea exulans) and Amsterdam Albatross (D. amsterdamensis) in the South Pacific and Spectacled Petrel (Procellaria conspicillata) in the South Atlantic. Because pelagic longline fisheries involve multinational fleets operating in vast ocean regions, assessing total bycatch levels for a seabird is challenging. Here we present a case study of quantifying bycatch from a basin-wide pelagic longline fishery and assessing the populationlevel impact on a vulnerable seabird, the Black-footed Albatross (Phoebastria nigripes) in the central North Pacific. We develop an assessment method that uses observer data to estimate bycatch for one fleet and then uses scenario analysis to estimate bycatch for remaining fleets. Our method generates a bounded estimate of bycatch ithin an ocean region, ranging from the worstcase to the bestcase bycatch scenario. We find that Blackfooted Albatross mortality across all fleets in the central North Pacific may total as much as 10 000 individuals/yr. At this level of mortality, population declines are likely. However, even at the bestcase bycatch estimate (5200 individuals/yr), population declines may occur over the next three generations (60 years). Although this analysis requires extensive estimation and extrapolation from existing data, it is critical to provide fisheries managers with bounded estimates of likely population-level effects of current fishing activity.

— The data on the occurrence, distribution, and some biological and ecological features of Adelosebastes latens are given for the first time based on samples collected in the region of the Hawaiian-Emperor Seamount Chain during longline fishery. This comparatively rare representative of rockfishes is registered on the slopes of Jingu, Ojin, Lira, and Koko seamounts at the depths between 512 and 1068 m. The catches include individuals 24–39 cm body length and 180–1085 g body weight at the age 15–30 years. The onset of sexual maturity is different in the males and females. We suggest that A. latens is oviparous species with internal fertilization, and eggs are released in the spring.

Fisheries bycatch is one of the biggest threats to marine mammal populations. A literature review was undertaken to provide a comprehensive assessment and synopsis of gear modifications and technical devices to reduce marine mammal bycatch in commercial trawl, purse seine, longline, gillnet and pot/trap fisheries. Successfully implemented mitigation measures include acoustic deterrent devices (pingers) which reduced the bycatch of some small cetacean species in gillnets, appropriately designed exclusion devices which reduced pinniped bycatch in some trawl fisheries, and various pot/trap guard designs that reduced marine mammal entrapment. However, substantial development and research of mitigation options is required to address the bycatch of a range of species in many fisheries. No reliably effective technical solutions to reduce small cetacean bycatch in trawl nets are available, although loud pingers have shown potential. There are currently no technical options that effectively reduce marine mammal interactions in longline fisheries, although development of catch and hook protection devices is promising. Solutions are also needed for species, particularly pinnipeds and small cetaceans, that are not deterred by pingers and continue to be caught in static gillnets. Large whale entanglements in static gear, particularly buoy lines for pots/traps, needs urgent attention although there is encouraging research on rope-less pot/trap systems and identification of rope colours that are more detectable to whale species. Future mitigation development and deployment requires rigorous scientific testing to determine if significant bycatch reduction has been achieved, as well as consideration of potentially conflicting mitigation outcomes if multiple species are impacted by a fishery.

Incidental mortality (bycatch) in fisheries remains the greatest threat to many large marine vertebrates and is a major barrier to fisheries sustainability. Robust assessments of bycatch risk are crucial for informing effective mitigation strategies, but are hampered by missing information on the distributions of key life‐history stages (adult breeders and non‐breeders, immatures and juveniles). Using a comprehensive biologging dataset (1,692 tracks, 788 individuals) spanning all major life‐history stages, we assessed spatial overlap of four threatened seabird populations from South Georgia, with longline and trawl fisheries in the Southern Ocean. We generated monthly population‐level distributions, weighting each life‐history stage according to population age structure based on demographic models. Specifically, we determined where and when birds were at greatest potential bycatch risk, and from which fleets. Overlap with both pelagic and demersal longline fisheries was highest for black‐browed albatrosses, then white‐chinned petrels, wandering and grey‐headed albatrosses, whereas overlap with trawl fisheries was highest for white‐chinned petrels. Hotspots of fisheries overlap occurred in all major ocean basins, but particularly the south‐east and south‐west Atlantic Ocean (longline and trawl) and south‐west Indian Ocean (pelagic longline). Overlap was greatest with pelagic longline fleets in May–September, when fishing effort south of 25°S is highest, and with demersal and trawl fisheries in January–June. Overlap scores were dominated by particular fleets: pelagic longline—Japan, Taiwan; demersal longline and trawl—Argentina, Namibia, Falklands, South Africa; demersal longline—Convention for Conservation of Antarctic Marine Living Resources (CCAMLR) waters, Chile, New Zealand. Synthesis and applications. We provide a framework for calculating appropriately weighted population‐level distributions from biologging data, which we recommend for future fisheries bycatch risk assessments. Many regions of high spatial overlap corresponded with high seabird bycatch rates recorded by on‐board observers, indicating that our approach reliably mapped relative bycatch risk at large spatial scales. Implementation of effective bycatch mitigation in these high‐risk regions varies considerably. Although potential bycatch risk appears to have decreased since the early 2000s, albatross and petrel populations from South Georgia and elsewhere are still declining, emphasizing the need for much improved observer coverage and monitoring of compliance with bycatch regulations. 摘要 漁業活動中的意外捕獲(bycatch)造成許多海洋脊椎動物嚴重的生存威脅，意外捕獲也是漁業永續經營的主要障礙。而對意外捕獲風險做出可靠的風險評估，對於提出有效的忌避策略至關重要，然而卻受限於缺少這些受脅物種生活史各個關鍵階段(繁殖期成鳥、非繁殖成鳥、亞成鳥、幼鳥)的分布資料。 使用獨特的全面生物資料輸入數據組(1697項追蹤、790個體)，資料涵蓋了生活史各個主要階段，我們評估了在南喬治亞4種受脅海鳥族群範圍，與在南冰洋的延繩釣及拖繩漁業作業範圍的重疊情形。將資料套用族群模式推估出族群年齡結構，再將生活史各階段賦予權重，我們製作了每月族群分布圖。我們更針對性指出特定海鳥在那一個季節、那一個海域受到意外捕獲的最高風險，以及是被那一類漁船所威脅。 與浮延繩釣及底延繩釣作業區域重疊最高的是黑眉信天翁，其次為白額鸌、漂泊信天翁、灰頭信天翁。與拖繩漁業區域重疊最高的是白額鸌。 海鳥族群與漁業重疊熱點發生在所有主要的海盆，特別是在大西洋的西南部及東南部（延繩釣及拖網漁業），印度洋西南（浮延繩釣漁業）。對於遠洋浮延繩釣船隊而言重疊度最高是在5月至9月，這時在南緯25度以南的漁業作業最頻繁，底延繩釣及拖網漁業高峰則在1月至6月。重疊指數被特定船隊所主導: 浮延繩釣為日本及臺灣; 底延繩釣及拖網為阿根廷、納米比亞、福克蘭、南非；CCAMLR海域的底延繩釣為智利、紐西蘭。 綜合及應用：我們提供了一個架構可以用生物資訊輸入數據，計算經合理權重後的族群分布，我們建議未來可應用於意外捕獲風險評估。許多高度重疊區域呼應了由隨船觀察員紀錄的高海鳥意外捕獲率，顯示出我們這個方法可製作可信度高的意外捕獲風險地圖。在這些高風險區域安排有效海鳥忌避措施的作法有相當大的差異。雖然自2000年初以來，潛在意外捕獲風險看似降低，但南喬治亞及其它地區的信天翁及水薙鳥的族群數量仍在下降，更突顯出需要改進意外捕獲規定中觀察員覆蓋度，以及改善監測漁船忌避措施規定的遵守。 要旨 漁業による偶発的な死（混獲）は未だに多くの大型海洋性脊椎動物にとって最大の脅威であり、持続可能な漁業の障害となっている。効果的な対策には頑健な混獲リスク評価が重要だが、生活環のステージごと（繁殖成体、非繁殖成体、幼体、亜成体）の分布情報の不足が妨げとなっている。 全ての主な生活環のステージを含む包括的なバイオロギングデータ（1697追跡、790個体）をもとに、サウスジョージアに生息する海鳥4種の絶滅危惧個体群と、南氷洋の延縄漁とトロール漁の空間的重複を評価した。月毎の海鳥個体群レベルの分布域の作成には、個体群統計モデルをもとに各生活環ステージの年齢構成を考慮した。特に、何時、何処で、どの船団によって海鳥が混獲リスクに晒される可能性が高いかを判定した。 浮延縄漁と底延縄漁との重複はマユグロアホウドリが最も高く、ノドジロクロミズナギドリ、ワタリアホウドリ、ハイガシラアホウドリが次いだ。トロール漁と の重複はノドジロクロミズナギドリが最も高かった。 漁業との重複が高いホットスポットは全ての主要海盆で判明したが、特に大西洋の南東域と南西域（延縄とトロール）、インド洋の南西域（浮延縄）で高かった。重複が最も高かったのは、浮延縄では南緯25度以南の漁獲努力量が最も高い5月から9月で、底延縄とトロールでは1月から6月であった。顕著に重複スコアが高かった特定の船団は以下のとおりであった：浮延縄 ‐日本、台湾；底延縄とトロール ‐ アルゼンチン、ナミビア、フォークランド諸島、南アフリカ；底延縄 ‐ CCAMLR海域、チリ、ニュージーランド。 総括と適用。今後の漁業による混獲リスク評価には、ここに示したようにバイオロギングデータをもとにした、また適切な考慮を含む、個体群レベルの分布計算の枠組みを推奨する。空間的重複が高いと推定された多くの海域では科学オブザーバーによっても高い混獲率が記録されており、この手法で混獲リスクを大きな空間スケールで的確にマッピングができることが示された。効果的な混獲対策の施行は、リスクの高い海域間で大きく異なっている。2000年代前半以降は潜在的な混獲リスクが減少したように見受けられるが、サウスジョージアやその他のアホウドリ類とミズナギドリ類の個体数は未だに減少しており、科学オブザーバーによるカバー率と混獲に関する規制順守のモニタリングの大幅な改善の必要性を強調する。 We provide a framework for calculating appropriately weighted population‐level distributions from biologging data, which we recommend for future fisheries bycatch risk assessments. Many regions of high spatial overlap corresponded with high seabird bycatch rates recorded by on‐board observers, indicating that our approach reliably mapped relative bycatch risk at large spatial scales. Implementation of effective bycatch mitigation in these high‐risk regions varies considerably. Although potential bycatch risk appears to have decreased since the early 2000s, albatross and petrel populations from South Georgia and elsewhere are still declining, emphasizing the need for much improved observer coverage and monitoring of compliance with bycatch regulations.

Spatial management for highly migratory species (HMS) is difficult due to many species’ mobile habits and the dynamic nature of oceanic habitats. Current static spatial management areas for fisheries in the United States have been in place for extended periods of time with limited data collection inside the areas, making any analysis of their efficacy challenging. Spatial modeling approaches can be specifically designed to integrate species data from outside of closed areas to project species distributions inside and outside closed areas relative to the fishery. We developed HMS-PRedictive Spatial Modeling (PRiSM), which uses fishery-dependent observer data of species’ presence–absence, oceanographic covariates, and gear covariates in a generalized additive model (GAM) framework to produce fishery interaction spatial models. Species fishery interaction distributions were generated monthly within the domain of two HMS longline fisheries and used to produce a series of performance metrics for HMS closed areas. PRiSM was tested on bycatch species, including shortfin mako shark (Isurus oxyrinchus), billfish (Istiophoridae), and leatherback sea turtle (Dermochelys coriacea) in a pelagic longline fishery, and sandbar shark (Carcharhinus plumbeus), dusky shark (C. obscurus), and scalloped hammerhead shark (Sphyrna lewini) in a bottom longline fishery. Model validation procedures suggest PRiSM performed well for these species. The closed area performance metrics provided an objective and flexible framework to compare distributions between closed and open areas under recent environmental conditions. Fisheries managers can use the metrics generated by PRiSM to supplement other streams of information and guide spatial management decisions to support sustainable fisheries.