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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.

1. Many animal taxa exhibit sex-specific variation in ecological traits, such as foraging and distribution. These differences could result in sex-specific responses to change, but such demographic effects are poorly understood. 2. Here, we test for sex-specific differences in the demography of northern (NGP, Macronectes halli) and southern (SGP, M. giganteus) giant petrels-strongly sexually size-dimorphic birds that breed sympatrically at South Georgia, South Atlantic Ocean. Both species feed at sea or on carrion on land, but larger males (30% heavier) are more reliant on terrestrial foraging than the more pelagic females. Using multi-event mark-recapture models, we examine the impacts of long-term changes in environmental conditions and commercial fishing on annual adult survival and use two-sex matrix population models to forecast future trends. 3. As expected, survival of male NGP was positively affected by carrion availability, but negatively affected by zonal winds. Female survival was positively affected by meridional winds and El Niño-Southern Oscillation (ENSO), and negatively affected by sea ice concentration and pelagic longline effort. Survival of SGPs did not differ between sexes; however, survival of males only was positively correlated with the Southern Annular Mode (SAM). 4. Two-sex population projections indicate that future environmental conditions are likely to benefit giant petrels. However, any potential increase in pelagic longline fisheries could reduce female survival and population growth. 5. Our study reveals that sex-specific ecological differences can lead to divergent responses to environmental drivers (i.e. climate and fisheries). Moreover, because such effects may not be apparent when all individuals are considered together, ignoring sex differences could underestimate the relative influence of a changing environment on demography. K E Y W O R D S giant petrels, Macronectes giganteus, Macronectes halli, sex-specific effects, sexual size dimorphism, South Georgia, Southern Ocean, survival

Aim Networks of connected marine protected areas (MPAn) are recognized as the key area‐based management tool to preserve biodiversity, moderate exploitation of marine resources and increase ecological resilience to climate change. Although population genetic studies could greatly benefit connectivity assessments between MPAs, genetic data are rarely used in MPAn planning. Here, we aim to illustrate the use of a multispecies and multilocus approach to provide recommendations for MPAn design, highlighting the importance of the species selected and the analyses performed. Our study is focused on the Southern Ocean, an area of keen multinational interest given its scientific significance, economic importance and its unique, shared legal status. Location South Georgia and South Sandwich Islands MPA (SGSSI MPA), the South Orkney Islands and the Western Antarctic Peninsula (WAP)—where an MPA was proposed in 2018 (Domain 1 MPA) but has not been approved by the Commission for the Conservation of the Antarctic Marine Living Resources (CCAMLR). Methods Our datasets include 819 individuals from five different species with contrasting life‐history strategies: two nemerteans (Antarctonemertes valida and A. riesgoae), two annelids (Pterocirrus giribeti and Neanthes kerguelensis) and one sponge (Mycale [Oxymycale] acerata). To identify genetic connectivity patterns in our study area, spanning roughly 2500 km, we used the COI mitochondrial marker and genome‐wide ddRADseq‐derived SNPs. Results A consistent lack of connectivity between SGSSI MPA and the WAP was found for all studied species. Additionally, our data indicated a stepping‐stone role for the South Orkney Islands between these two genetically differentiated regions. Main conclusions Our results reveal how the application of comparative phylogeography and population genomics can guide policymakers in their decision‐making process during MPAn design. We detected priority areas for conservation in Antarctica, including the South Orkney Islands and the WAP, providing strong evidence for the implementation of the Domain 1 MPA.

AIM: Ecological niche modelling can provide valuable insight into species' environmental preferences and aid the identification of key habitats for populations of conservation concern. Here, we integrate biologging, satellite remote‐sensing and ensemble ecological niche models (EENMs) to identify predictable foraging habitats for a globally important population of the grey‐headed albatross (GHA) Thalassarche chrysostoma. LOCATION: Bird Island, South Georgia; Southern Atlantic Ocean. METHODS: GPS and geolocation‐immersion loggers were used to track at‐sea movements and activity patterns of GHA over two breeding seasons (n = 55; brood‐guard). Immersion frequency (landings per 10‐min interval) was used to define foraging events. EENM combining Generalized Additive Models (GAM), MaxEnt, Random Forest (RF) and Boosted Regression Trees (BRT) identified the biophysical conditions characterizing the locations of foraging events, using time‐matched oceanographic predictors (Sea Surface Temperature, SST; chlorophyll a, chl‐a; thermal front frequency, TFreq; depth). Model performance was assessed through iterative cross‐validation and extrapolative performance through cross‐validation among years. RESULTS: Predictable foraging habitats identified by EENM spanned neritic (<500 m), shelf break and oceanic waters, coinciding with a set of persistent biophysical conditions characterized by particular thermal ranges (3–8 °C, 12–13 °C), elevated primary productivity (chl‐a > 0.5 mg m⁻³) and frequent manifestation of mesoscale thermal fronts. Our results confirm previous indications that GHA exploit enhanced foraging opportunities associated with frontal systems and objectively identify the APFZ as a region of high foraging habitat suitability. Moreover, at the spatial and temporal scales investigated here, the performance of multi‐model ensembles was superior to that of single‐algorithm models, and cross‐validation among years indicated reasonable extrapolative performance. MAIN CONCLUSIONS: EENM techniques are useful for integrating the predictions of several single‐algorithm models, reducing potential bias and increasing confidence in predictions. Our analysis highlights the value of EENM for use with movement data in identifying at‐sea habitats of wide‐ranging marine predators, with clear implications for conservation and management.

Aim Marine protected areas can serve to regulate harvesting and conserve biodiversity. Within large multi‐use MPAs, it is often unclear to what degree critical sites of biodiversity are afforded protection against commercial activities. Addressing this issue is a prerequisite if we are to appropriately assess sites against conservation targets. We evaluated whether the management regime of a large MPA conserved sites (Key Biodiversity Areas, KBAs) supporting the global persistence of top marine predators. Location Southwest Atlantic Ocean. Method We collated population and tracking data (1,418 tracks) from 14 marine predator species (Procellariiformes, Sphenisciformes, Pinnipedia) that breed at South Georgia and the South Sandwich Islands, and identified hotspots for their conservation under the recently developed KBA framework. We then evaluated the spatiotemporal overlap of these sites and the different management regimes of krill, demersal longline and pelagic trawl fisheries operating within a large MPA, which was created with the intention to protect marine predator species. Results We identified 12 new global marine KBAs that are important for this community of top predators, both within and beyond the focal MPA. Only three species consistently used marine areas at a time when a potentially higher‐risk fishery was allowed to operate in that area, while other interactions between fisheries and our target species were mostly precluded by MPA management plans. Main conclusions We show that current fishery management measures within the MPA contribute to protecting top predators considered in this study and that resource harvesting within the MPA does not pose a major threat—under current climate conditions. Unregulated fisheries beyond the MPA, however, pose a likely threat to identified KBAs. Our approach demonstrates the utility of the KBA guidelines and multispecies tracking data to assess the contributing role of well‐designed MPAs in achieving local and internationally agreed conservation targets.

Aim: We assess biogeographical patterns, population structure and the range of species in the pulmonate genus Siphonaria across the sub-Antarctic. We hypothesized that locally endemic cryptic species will be found across the distribution of these direct-developing limpets in the sub-Antarctic. Location: The sub-Antarctic coasts of the Southern Ocean including South America, the Falkland/Malvinas, South Georgia, Kerguelen and Macquarie Islands. Methods: Multi-locus phylogenetic reconstructions, mtDNA time-calibrated divergence time estimations and population-based analyses of Siphonaria populations were used at the scale of the Southern Ocean. Results: We resolve two widely distributed lineages of Siphonaria (S. lateralis and S. fuegiensis) across the sub-Antarctic. MtDNA divergence time estimates suggest that they were separated around 4.0 Ma (3.0 to 8.0 Ma). Subsequently both species followed different evolutionary pathways across their distributions. Low levels of genetic diversity characterize the populations of both species, reflecting the role of Quaternary glacial cycles during their respective demographic histories, suggesting high levels of dispersal among geographically distant localities. Main conclusions: Siphonaria lateralis and S. fuegiensis constitute sister and broadly co-distributed species across the sub-Antarctic. Unexpected transoceanic similarities and low levels of genetic diversity in both these direct-developing species imply recurrent recolonization processes through long-distance dispersal to isolated sub-Antarctic islands. For such groups of Southern Ocean invertebrates, rafting may be more effective for long-distance dispersal than a free-living planktotrophic larval stage. This biogeographical model may explain why many marine species lacking a dispersal phase exhibit broad distributions, low genetic diversity and low population structure over thousands of kilometres.

The Subantarctic island of South Georgia lost most of its birds to predation by rodents introduced by people over 2 centuries. In 2011 a UK charity began to clear brown rats Rattus norvegicus and house mice Mus musculus from the 170 km long, 3,500 km2 island using helicopters to spread bait containing Brodifacoum as the active ingredient. South Georgia's larger glaciers were barriers to rodent movement, resulting in numerous independent sub-island populations. The eradication could therefore be spread over multiple seasons, giving time to evaluate results before recommencing, and also reducing the impact of non-target mortality across the island as a whole. Eradication success was achieved in the 128 km2 Phase 1 trial operation. Work in 2013 (Phase 2) and early 2015 (Phase 3) covered the remaining 940 km2 occupied by rodents. By July 2017, 28 months after baiting was concluded, there was no sign of surviving rodents, other than one apparently newly introduced by ship in October 2014. A survey using detection dogs and passive devices will search the Phase 2 and Phase 3 land for rodents in early 2018. Seven (of 30) species of breeding birds suffered losses from poisoning, but all populations appear to have recovered within 5 years. The endemic South Georgia pipit Anthus antarcticus was the first bird to breed in newly rat-free areas, but there were also signs that cavity-nesting seabirds were exploring scree habitat denied them for generations. Enhanced biosecurity measures on South Georgia are needed urgently to prevent rodents being reintroduced.

Routine respiration rates in the South Georgia stock of Antarctic krill (Euphausia superba) were measured to compare with previously published measurements on stocks from colder locations further south. Within the natural temperature range of this species (− 1.8° to 5.5 °C), respiration rate data from both the present and previous studies were adequately fitted by a single Arrhenius regression (Q10 of 2.8), although South Georgia krill showed an upward deviation from this regression between 0° and 2 °C (the lower temperature range at South Georgia). Metabolic compensation (i.e. the comparative lowering of respiration rate) at the high temperatures experienced at South Georgia was not apparent, although the higher than predicted metabolic rates at low temperatures suggests acclimation of South Georgia krill to a warm water lifestyle. Weight-specific respiration rate was significantly higher in sub-adults and adults compared to juveniles, highlighting the metabolic burden of reproduction. South Georgia krill showed no further increase in respiration rate when exposed to acute temperatures (5.5–12.2 °C), indicating that they were already at the limit of aerobic capacity by 5.5 °C. Overall, this study shows that even small degrees of additional warming to South Georgia waters are likely to make conditions there metabolically unsustainable for Antarctic krill.