Seabird Mortality Research Articles

Geographic, ecological, and temporal patterns of seabird mortality during the 2022 HPAI H5N1 outbreak on the island of Newfoundland

Highly pathogenic avian influenza H5N1 caused mass mortality of wildlife across the North Atlantic in 2022. Following European outbreaks, the first North American case was detected on the island of Newfoundland, Canada in November 2021, before spreading throughout North America. During the following summer, Newfoundland and surrounding islands (NFLD) experienced one of the most significant mortalities in Canadian provinces, with seabirds being the most affected taxa. From surveys and citizen reports, we estimate that 13517 mortalities that can be attributed to HPAI occurred in NFLD from April to September 2022. Most estimated mortalities were among Northern Gannets (Morus bassanus, Linnaeus, 1758) (6596), Common Murres (Uria aalge, Pontoppidan, 1763) (5992), Atlantic Puffins (Fratercula arctica, Linnaeus, 1758) (282), and Black-legged Kittiwakes (Rissa tridactyla, Linnaeus, 1758) (217). Mortality reports moved from west to east along the southern then eastern NFLD coast and peaked in July and August. We formulated exploratory hypotheses regarding traits that could contribute to infection and mortality. Species differences in mortality most strongly associated with inter-nest distance, breeding phenology, and at-sea overlap with allospecifics from other colonies. Unprecedented seabird mortality and ongoing transmission within the circulating avian influenza viruses highlight the need for continued monitoring and development of conservation strategies.

Evidence of Ecosystem Tipping Point on St. Lawrence Island: Widespread Lake Drainage Events After 2018

AbstractInfluenced by climate change, numerous lakes in permafrost regions are draining, showing significant spatial variability. This study focuses on St. Lawrence Island, where over the last two decades, 771 of 3,271 lakes have drained—a rate around 40 times higher than across the entire northern permafrost region. The surge in lake drainage began in 2018, coinciding with record low sea ice extent in the Bering Sea and unprecedented bird mortalities. Using satellite imagery and machine learning methods, we analyzed drainage events to identify the climatic drivers and potential climate thresholds affecting the island's lake ecosystems. Our findings indicate that autumn peak temperatures above 6°C more than triple the drainage probability, and warming‐induced permafrost thawing may be the direct driver of lake drainage. This research highlights the vulnerability of Arctic lake ecosystems to climate change and assists in developing predictive models for permafrost response, crucial for mitigating impacts on Arctic communities.

Cyclone Ilsa in April 2023 led to significant seabird mortality on Bedout Island

On 13 April 2023, Cyclone Ilsa crossed Bedout Island in the Timor Sea off Western Australia’s remote north coast. Extensive damage was done to the entire island, with all coastal vegetation stripped clear from the island’s surface. Here we use repeated aerial and ground-based transect surveys of Bedout’s important seabird populations during 17 April – 21 July 2023 and Monte Carlo modelling to estimate total mortality for three species. We estimate that 80–90% of the populations of three seabird species (Masked Booby Sula dactylatra bedouti, Brown Booby S. leucogaster, and Lesser Frigatebird Fregata ariel) were killed in the storm, with only 40 breeding Masked Booby (a putative endemic subspecies) recorded on the island 15 weeks later. The frequency and intensity of such storms is likely approaching a threshold beyond which Bedout’s seabirds cannot readily recover, with cyclones hitting the island, on average, every seven years in recent decades. We discuss the implications for Bedout Island, and for wildlife conservation more broadly in the face of increasing, climate-driven storms and impacts documented worldwide.

Investigation of a Mass Stranding Event Reveals a Novel Pattern of Cascading Comorbidities in Northern Fulmars (Fulmarus glacialis).

During 2018, a seabird mortality event occurred in central California, US, that affected Northern Fulmars (Fulmarus glacialis), Common Murres (Uria aalge), and Cassin's Auklets (Ptychoramphus aleuticus). An increase in beachcast birds were reported on standardized surveys in conjunction with an increased number of live-stranded birds admitted to rehabilitation centers. Neurologic symptoms were noted during intake examination for some birds. Coincident with the mortality event, increased levels of the harmful algal bloom toxins domoic acid and saxitoxin were recorded in Monterey Bay and Morro Bay. Birds that died in care and beachcast carcasses were submitted to the California Department of Fish and Wildlife-Marine Wildlife Veterinary Care and Research Center for postmortem examination (n=24). All examined birds were emaciated. Examined Common Murres and Cassin's Auklets had no gross evidence of preexisting disease; however, all examined Northern Fulmars exhibited severe pyogranulomatous inflammation of the urogenital system at gross postmortem exam. Tissues from nine Northern Fulmars were examined by histopathology, and samples from two Northern Fulmars were tested for the presence of domoic acid and saxitoxin. Histopathology revealed moderate to severe kidney infection by Eimeria sp. and gram-negative bacteria, intratubular urate stasis, ureter rupture, and emaciation. Additionally, domoic acid and saxitoxin were detected simultaneously in tissues of some tested birds. This communication highlights a novel pattern of cascading comorbidities in native seabirds from a mass stranding event.

Highly pathogenic avian influenza: Unprecedented outbreaks in Canadian wildlife and domestic poultry.

Canada experienced a wave of HPAI H5N1 outbreaks in the spring of 2022 with millions of wild and farmed birds being infected. Seabird mortalities in Canada have been particularly severe on the Atlantic Coast over the summer of 2022. Over 7 million birds have been culled in Canada, and outbreaks continue to profoundly affect commercial bird farms across the world. This new H5N1 virus can and has infected multiple mammalian species, including skunks, foxes, bears, mink, seals, porpoises, sea lions, and dolphins. Viruses with mammalian adaptations such as the mutations PB2-E627K, E627V, and D701N were found in the brain of various carnivores in Europe and Canada. To date this specific clade of H5N1 virus has been identified in less than 10 humans. At the ground level, awareness should be raised among frontline practitioners most likely to encounter patients with HPAI.

Incidental mortality of seabirds in pollock trawl fishery in the northwestern part of the Bering Sea

Purpose of the work: Estimation of average annual number of seabirds that die as a result of lethal strikes with fishing gear in the specialized pollock trawl fishery by large-tonnage fleet in the West Bering Sea zone.Methods used: The article is based on materials collected by ornithologists on large freezer trawlers in the summer and autumn periods in 2020 and 2021. To record bird deaths we used inspection of warps, net sonar wire third cable, net trawl, codend during trawl retrieval and count of bird lethal collisions with fishing gear during observation sessions at all stages of fishing operations. The total mortality was estimated by extrapolating the mean catch-rates (number of dead birds per vessel day) to fishing efforts of large-tonnage fleet in the West Bering Sea zone in 2020 and 2021.Novelty: The annual average mortality of birds in large-scale trawling was determined for the first time for domestic fisheries and an expert assessment of its potential risk to populations of the catched species was carried outResults: The death of 203 birds was recorded during 139 vessel days. The total estimated mortality in fishing gear was 8,355 (CI 5259–11451) birds per year: 4,717 northern fulmars, 1,667 short-tailed shearwaters, 1,006 Laysan albatrosses, 822 black-legged kittiwakes, 48 slaty-backed gulls, 48 Vega gulls, and 47 red-legged kittiwakes. Comparison of these estimates with the global or regional number of birds suggests that mortality in fishing gear in 2020 and 2021 did not have a significant negative impact on the state of species (proportion of dead birds was 0.005–0.085% of their population estimates). Despite the regular presence of short-tailed albatrosses near trawlers in the Navarin area, no deaths in fishing gear were recorded.Practical significance: The results are necessary for the process of ecological certification of the specialized pollock trawl fishery in the West Bering Sea zone.

Bird scaring lines reduce seabird mortality in mid-water and bottom trawlers in Argentina

Abstract Seabird bycatch in fisheries, and the development of effective mitigation to minimize this, have been subject to increasing research attention over the past three to four decades. Trawl fisheries represent a particular challenge, as bird mortalities (especially highly threatened albatrosses and large petrels, Procellariforms) occur primarily through difficult-to-detect collisions with warp and net monitoring cables. Effectiveness of bird-scaring lines (BSLs) as a mitigation measure can be fleet-specific, and studies relating specifically to reducing collisions with the net monitoring cable are rare. To support improved assessment and mitigation of seabird bycatch in trawl fisheries, we studied the mortality associated with mid-water and bottom factory trawl vessels along the southern tip of the Argentine Patagonian shelf, across 2144 trawls from 2012 to 2019, with three specific objectives: (i) inform improved bycatch management in this (and other) trawl fisheries by analysing differences in seabird collision rates and outcomes between net monitoring and warp cables, as well as the effect of mitigation measures in reducing collisions; (ii) explore the effects of key fishing operation variables on seabird impact outcomes; and (iii) estimate the annual seabird mortality in the study fleet. We tested the efficacy of BSLs as a mitigation measure to reduce seabird mortality, on warps and net monitoring cables. Our results show that seabird mortality increases in the presence of a net monitoring cable. Our estimation of fishery-wide mortality without the use of BSLs includes 108 [31–186] Southern royal albatross (Diomedea epomophora) and 279 [108–465] Black-browed albatross (Thalassarche melanophris) killed annually by the collisions with the net monitoring cable. We demonstrate the efficacy of BSLs in reducing the number of collisions and in combination with no discarding of fishes, seabird interactions fell to c. zero. Our study builds the case for better bycatch data collection in trawl fisheries, the strong influence of discarding, and the feasibility of simple mitigation measures to reduce seabird bycatch, including on the net monitoring cable.

Advances in Scale Assessment of Seabird Bycatch: A New Methodological Framework

This paper presents a methodology for indirectly estimating the scale of seabird bycatch using existing data. The study focuses on five key species of ducks that winter in the Polish waters of the Baltic Sea and are highly susceptible to bycatch: Long-tailed Duck, Velvet Scoter, Common Scoter, Greater Scaup, and Tufted Duck. The evaluation units used are divided into the Bornholm (BS) and Gotland Subdivisions (GS) within the Polish Exclusive Economic Zone (PEEZ). The analysis acknowledges the lack of bycatch data for certain areas known to have high concentrations of diving birds and fishing activity. The population sizes of waterbirds were assessed using ship-based surveys and a distance sampling approach. Fishing effort data from the five winter seasons between 2015/2016 and 2019/2020 were analyzed. Bycatch rates were estimated based on surveys conducted in previous seasons, and threshold values for bycatch were established using the concept of “small numbers” defined in EU directives. The results show that within the GS of the PEEZ, the estimated average abundance of all diving waterbirds was 174,800 individuals, with an average annual bycatch of 7921 birds (4.5% of the total). The Velvet Scoter was the most abundant species, followed by the Long-tailed Duck. In the BS, the estimated average abundance of diving waterbirds was 624,600 individuals, with an average annual bycatch of 5056 birds (0.8% of the total). The Long-tailed Duck was the most numerous species, followed by the Velvet Scoter. Acceptable bycatch thresholds were exceeded for all species in both subdivisions despite a much smaller scale of bycatch in the BS. The findings highlight the need for effective management and conservation measures to address the high mortality of seabirds due to bycatch. The methodology presented in this study offers a valuable approach for estimating bycatch scale and can support efforts to minimize the impact on seabird populations.

Mitigation of seabird bycatch in New Zealand squid trawl fisheries provides hope for ongoing solutions

ABSTRACT Although there is an increasing awareness of the high rates of seabird bycatch in trawl fisheries globally, there is relatively limited implementation of effective mitigation measures. Seabirds that are attracted to the stern of the trawl vessel to feed on fish-waste can be drowned or injured when they collide with warps/cables or when they become entangled in nets. Managing fish-waste discharge (processing offal and discards) and limiting access to it by scaring birds have been identified as the most effective measures to reduce seabird mortality from collisions with warps. New Zealand’s arrow squid (Nototodarus spp.) trawl fishery occurs during the austral summer and autumn when there is significant overlap with large numbers of foraging seabirds due to the proximity of breeding areas. Regulations introduced by the New Zealand government in 2007 requiring the use of devices to reduce warp strikes and operational procedures to manage fish-waste were independently implemented by the fishing industry in 2007 with the support of fishery regulators. The rate of capture of albatrosses by warps decreased from a mean of 2.9 birds per 100 tows during the period 2003 to 2006 to a mean of 0.7 birds per 100 tows after 2007. Long-term ownership of squid fishery quota catalysed the proactive engagement of the industry and has been reflected in a positive cultural shift in the attitude of fishers towards managing the risk of the capture of seabirds. Multi-sector collaboration and engagement allowed for the translation of experimental mitigation results into long-term, industrial-scale operational practices.

A simple but novel approach to calculate seabird light fallout: A case study from Kauaʻi

Injury and mortality of night flying seabirds due to lights (fallout) affects their long-term viability. However, the cryptic nature of these species hinders direct estimates and projections of fallout. The Kauaʻi Seabird Habitat Conservation Plan (KSHCP) characterizes the current and projected fallout for Newell's shearwaters (Puffinus auricularis newelli), Hawaiian petrels (Pterodroma sandwichensis) and the Hawaiʻi distinct population segment of the band-rumped storm-petrels (Oceanodroma castro) on the island of Kauaʻi across eight permittees. In the KSHCP, each permittee was required to itemize the lighting infrastructure related to their facilities (type, wattage, number of lights, etc.) as well as supply an overall expected seabird fallout number with an estimate of detection probability or ability to find the fallout birds. Light intensity is thought to be correlated to the degree of attraction to a light source. Here we identify seabird fallout using indirect estimates derived from the KSHCP and present a reproducible method to consistently project and calculate fallout between entities that need to reduce seabird mortality due to their light sources. Though the permittees did not provide an estimate of light intensity at their sites, we extrapolated luminous intensity (light brightness) from their itemized light information (i.e., lumens/watt). Using luminous intensity, we then derived the degree of fallout per lumen and its variation across the permittees. As a proof of concept, we then projected the fallout per lumen estimate onto streetlights owned by the Kauaʻi Island Utility Cooperative, as applied over a range of detectability correction factors. Though fallout varies significantly based on the detectability correction factor used, when considering the site differences on Kauaʻi, a previous fallout estimate, and the overlapping characteristics of the projected versus actual luminous intensities, the utilities projected fallout appears applicable. We feel that the methodology can be used as a baseline to infer fallout associated with various entities.

Pelagic seabirds reduce risk by flying into the eye of the storm

Cyclones can cause mass mortality of seabirds, sometimes wrecking thousands of individuals. The few studies to track pelagic seabirds during cyclones show they tend to circumnavigate the strongest winds. We tracked adult shearwaters in the Sea of Japan over 11 y and found that the response to cyclones varied according to the wind speed and direction. In strong winds, birds that were sandwiched between the storm and mainland Japan flew away from land and toward the eye of the storm, flying within ≤30 km of the eye and tracking it for up to 8 h. This exposed shearwaters to some of the highest wind speeds near the eye wall (≤21 m s-1) but enabled them to avoid strong onshore winds in the storm's wake. Extreme winds may therefore become a threat when an inability to compensate for drift could lead to forced landings and collisions. Birds may need to know where land is in order to avoid it. This provides additional selective pressure for a map sense and could explain why juvenile shearwaters, which lack a map sense, instead navigating using a compass heading, are susceptible to being wrecked. We suggest that the ability to respond to storms is influenced by both flight and navigational capacities. This may become increasingly pertinent due to changes in extreme weather patterns.

Reconstruction of epizootic outbreak provoked the largescale death of Rhinoceros auklet on the coast of the Japan Sea in the Southern part of Primorsky Krai (July, 2021)

Introduction. In July 2021, a mass mortality of seabirds of unclear etiology occurred on the coast of the Sea of Japan in the Khasansky district of Primorsky Krai. According to the Department for Protection of Wildlife and Specially Protected Natural Territories of Primorsky Krai, over a thousand dead birds were found on the coast. The main case occurred in the population of birds Rhinoceros auklets (Cerorhinca monocerata, Alcidae), also among the dead birds were found several dozens of gulls (Larus spp.) and terns (Sterna spp.), single individuals of other species. The peak of mortality in bird populations occurred on July 13–17, 2021. This territory is a recreational area, in the summer months a large number of people rest there. The current situation has caused increased attention of the entire scientific community, as well as organizations that protect the citizens health and the environment. The aim. To establish possible etiology of the epizootic outbreak and describe the cause of birds’ death.Materials and methods. Comprehensive examination using classical methods of virology, microbiology and toxicology, as well as the most modern research methods such as MALDI TOF-mass spectrometry and NGS.Conclusion. As a result of the studies, it was determined that the cause of birds’ death was infectious peritonitis with endogenous intoxication syndrome induced by a complex of pathogenic microorganisms, such as enteropathogenic Escherichia coli, Proteus vulgaris, Proteus mirabilis, Proteus pennery, Enterococcus faecalis and Wickerhamomyces anomalus, related to Candida pelliculosa.

Disease surveillance in England and Wales, June 2022.

Disease surveillance in England and Wales, June 2022.

Seabird beachcast events associated with bycatch in the Norwegian purse seine fishery

Beachcast events, where a large number of seabird carcasses drift ashore, occur with irregular intervals. These events are due to specific situations where mass mortality of seabirds have occurred. Disentangling the cause of these events can provide valuable information on stressors impacting seabird populations. Following several mass mortality events involving gulls in northern Norway, an investigation of the probable cause of death was initiated. In total 75 dead gulls were collected at two occasions and necropsies were carried out. The findings from the necropsy of the gulls were consistent with drowning as the primary cause of death. Bycatch in coastal purse seine fishery was considered a potential cause of the mortality and monitoring of seabird bycatch in this fishery was thus initiated. The monitoring of fishing operations revealed that 10% of 91 fishing events observed led to bycatch, with a total of 32 bycaught seabirds. These bycatch events resulted in a total estimated bycatch rate of 0.356 (95% CI = 0.133–0.949) birds per haul. These findings are consistent with the hypothesis that the registered mortality events were caused by bycatch in the purse seine fishery. The highly episodic and unpredictable nature of these events makes it demanding to achieve solid estimates of the occurrence and extent of bycatch without a very high monitoring effort. Our study shows that systematic investigation following beachcast events can shed light on the occurrence of such extreme events.

Predicting the relative effectiveness of different management scenarios at reducing seabird interactions in a demersal trawl fishery

The incidental mortality in trawl fisheries is considered a conservation threat for many seabirds. We simulate management scenarios, combining bird scaring lines (BSL; zero, one and two) and variables describing discards (occurrence, levels, type, and mode), to predict the total seabird collisions with warp cables potentially produced by a demersal trawl fleet operating in a region and season of high seabird abundance. A total of 2067 collisions, including 439 heavy collisions and 53 fatal collisions, were recorded on five trips aboard the Uruguayan trawl fleet. One BSL reduced collisions and heavy collisions by 89%, and the associated mortality by 94%. Best management scenarios in terms of reducing collisions were those without discards, where the models with BSL outperformed the scenarios without BSL. Scenarios with two BSL presented slight improvements, likely caused by the small sample size. Under a scenario without discards, the mortality caused by the entire fleet is likely to be negligible. Given the inability to eliminate discards in most situations, we simulated scenarios of discharge produced in batches with BSL. This could drive mortality to negligible levels. We provide six recommended scenarios (S) ordered by expected reduction in seabird mortality. Fisheries implementing BSL as a single mitigation measure should present a strong reduction in seabird mortality. However, the ability to hold discards on board, at least partially, can drive mortality to negligible levels. This should occur without discards and BSL use (S1), without discards and without BSL (S2), and with batch discharge and BSL use (S3).

Mass mortality of seabirds in GB

Veterinary RecordVolume 190, Issue 3 p. 129-130 Wildlife Surveillance Mass mortality of seabirds in GB E Fullick, E Fullick veterinary investigation officer APHA Thirsk, North Yorkshire, YO7 1PZSearch for more papers by this authorCA Bidewell, CA Bidewell veterinary investigation officer APHA Bury St Edmunds, Suffolk, IP33 2RXSearch for more papers by this authorJP Duff, Corresponding Author JP Duff veterinary investigation officer paul.duff@apha.gov.uk APHA Penrith, Cumbria, CA11 9RRSearch for more papers by this authorJP Holmes, JP Holmes veterinary investigation officer APHA Shrewsbury, Shropshire, SY1 4HDSearch for more papers by this authorF Howie, F Howie veterinary investigation officers SRUC Veterinary Services, Pentlands Science Park, Bush Loan, Penicuik, Midlothian, EH26 0PZSearch for more papers by this authorC Robinson, C Robinson veterinary investigation officers SRUC Veterinary Services, Pentlands Science Park, Bush Loan, Penicuik, Midlothian, EH26 0PZSearch for more papers by this authorG Goodman, G Goodman lecturers in wildlife health and conservation medicineSearch for more papers by this authorKM Beckmann, KM Beckmann lecturers in wildlife health and conservation medicineSearch for more papers by this authorAW Philbey, AW Philbey senior lecturer in veterinary pathology Royal (Dick) School of Veterinary Studies and the Roslin Institute, University of Edinburgh, Easter Bush Campus, Midlothian, EH26 9RGSearch for more papers by this authorF Daunt, F Daunt animal population ecologist UK Centre for Ecology & Hydrology, Bush Estate, Penicuik, Midlothian, EH26 0QBSearch for more papers by this author E Fullick, E Fullick veterinary investigation officer APHA Thirsk, North Yorkshire, YO7 1PZSearch for more papers by this authorCA Bidewell, CA Bidewell veterinary investigation officer APHA Bury St Edmunds, Suffolk, IP33 2RXSearch for more papers by this authorJP Duff, Corresponding Author JP Duff veterinary investigation officer paul.duff@apha.gov.uk APHA Penrith, Cumbria, CA11 9RRSearch for more papers by this authorJP Holmes, JP Holmes veterinary investigation officer APHA Shrewsbury, Shropshire, SY1 4HDSearch for more papers by this authorF Howie, F Howie veterinary investigation officers SRUC Veterinary Services, Pentlands Science Park, Bush Loan, Penicuik, Midlothian, EH26 0PZSearch for more papers by this authorC Robinson, C Robinson veterinary investigation officers SRUC Veterinary Services, Pentlands Science Park, Bush Loan, Penicuik, Midlothian, EH26 0PZSearch for more papers by this authorG Goodman, G Goodman lecturers in wildlife health and conservation medicineSearch for more papers by this authorKM Beckmann, KM Beckmann lecturers in wildlife health and conservation medicineSearch for more papers by this authorAW Philbey, AW Philbey senior lecturer in veterinary pathology Royal (Dick) School of Veterinary Studies and the Roslin Institute, University of Edinburgh, Easter Bush Campus, Midlothian, EH26 9RGSearch for more papers by this authorF Daunt, F Daunt animal population ecologist UK Centre for Ecology & Hydrology, Bush Estate, Penicuik, Midlothian, EH26 0QBSearch for more papers by this author First published: 04 February 2022 https://doi.org/10.1002/vetr.1462Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume190, Issue35/12 February 2022Pages 129-130 RelatedInformation

Tracking Flights to Investigate Seabird Mortality Induced by Artificial Lights

Light pollution causes attraction and/or disorientation of seabirds, leading to mortality events due to multiple threats. This is a poorly understood phenomenon, largely because of the challenge to track seabirds at night from their nests to the grounding light-polluted locations. New tracking technologies can inform about this phenomenon. Here, we used GPS transmitters with remote download to track the flights of Cory’s shearwaterCalonectris borealisfledglings from an inland experimental releasing site to the ocean. We released birds assigned to three experimental groups: GPS tagged, tape-labelled, and control birds. We assessed how both intrinsic (such as body mass, body condition, body size, and down abundance) and extrinsic (i.e., flight descriptors, such as distance, straightness, and flight duration, wind speed, or moon luminance) factors influenced light-induced groundings by using two datasets: one including the three groups and another including just the GPS tagged birds (as GPS devices provide unique information). We tested whether the probability of being grounded by artificial lights was related to intrinsic factors. With the use of the whole dataset, we found that birds with a higher down abundance had a higher probability of being grounded. GPS data revealed that the probability of being grounded was positively related to the tortuosity of flights and the overflown light pollution levels. Also, birds with slower flights were more likely to be grounded than birds with fast flights. Tortuosity increased with light pollution levels but decreased with the ambient light of the moon. GPSs with remote data download provided information on birds reaching the ocean, this being a substantial improvement to previous studies requiring recapture of the individuals to retrieve the data. GPS tracks of birds reaching the ocean allowed us to know that some birds overflew coastal urban areas so light-polluted as the landing sites of grounded birds. We provide novel scientific-based information to manage seabird mortality induced by artificial lights.

Targeting efforts in rescue programmes mitigating light-induced seabird mortality: First the fat, then the skinny

Oceanic conditions determine food availability to seabirds and affect seabird reproductive parameters, such as breeding success, chick growth, and survival rates. In seabirds, juvenile survival at sea is positively correlated with body condition at fledging. In addition, in several seabird species, especially petrels and shearwaters (Order Procellariiformes), fledglings are disoriented by artificial lights during their maiden flights from their nests to the sea, and many of them fall on the ground and are rescued by volunteers to mitigate light-induced mortality. We studied variations in body condition and body mass in Cory’s Shearwater (Calonectris borealis) fledglings on Faial Island (Azores), using data from rescue campaigns conducted over 15 consecutive years. We checked if body condition was related to oceanic conditions. Late fledglings were in poorer body condition than early ones. Significant inter-annual variations in fledging body condition were observed. These were not related to North Atlantic Oscillation fluctuations. However, annual mean fledgling body condition was positively correlated with sea surface temperatures measured in the autumn of the previous year in a northern feeding area used by adults throughout the breeding season. This study broadens our knowledge of the factors affecting fledgling body condition in Procellariiformes and provides advice to better manage the rescue campaigns. Optimal management of rescue campaigns is essential given the limited economic or human resources allocated to such an aim.

Mitigating the impact of longline fisheries on seabirds: Lessons learned from the South Georgia Patagonian toothfish fishery (CCAMLR Subarea 48.3)

Seabird mortality in fisheries is a global problem and a major driver of the continued decline of many seabird populations. Unless appropriate mitigation is in place, longline fishing can cause high levels of seabird mortality. Here we describe the development and implementation of seabird mitigation measures in the Patagonian toothfish Dissostichus eleginoides fishery around the sub-Antarctic islands of South Georgia (CCAMLR Subarea 48.3), since the fishery began in the late 1980s. The initial high bycatch mortality (>5000 birds / 0.59 birds per 1000 hooks in 1996) has been reduced to negligible levels (<0.01 per 1000 hooks) through implementation of a suite of mitigation measures and a high level of compliance. The principal species killed in the fishery were black-browed albatross and white-chinned petrels, with most of the mortality occurring in April and early May. Whilst the synchronous introduction of much of the mitigation makes it is difficult to confirm which measures have been most effective, there is compelling evidence that the restriction of the fishery to the austral winter was a major factor. Night-setting and line-weighting measures have also been important in reducing mortality and the 100% observer coverage in the fishery has encouraged high levels of compliance. We also consider how different measures may be effective for different species and how novel measures, such as the use of marked hooks, have helped encourage compliance. The mitigation measures developed in the South Georgia fishery have subsequently been adopted in other CCAMLR fisheries and have helped guide global best practice in addressing seabird bycatch.

Spatial and temporal patterns of beached seabirds along the Chilean coast: Linking mortalities with commercial fisheries

The Chilean coast holds a high seabird diversity and also extensive fisheries that interact with birds producing bycatch. We used data on beached seabirds reported by news media to depict spatial and temporal patterns of fishery-related seabird mortality and correlated these data with the spatial and temporal fishing effort of the three main purse-seine fleets operating in south-central Chile (33 to 40°S). Between 2005 and 2019 we detected 97 mortality events reporting >19,000 beached seabirds attributed to bycatch. Mortality was recorded between 18 and 53° S (~3800 km of coastline), affecting 16 seabird species, with 90% concentrated between 33 and 40°S (800 km), exactly where purse-seine fleets operate. Sooty shearwater (Ardenna grisea) comprised 70% of all dead birds recorded. Magellanic penguins (Spheniscus magellanicus) and guanay cormorants (Phalacrocorax boungainvillii) were also affected. Mortality events of Sooty shearwaters was highest (P < 0.001) between February and May (54%) and October–November (36%), coinciding with the timing of the species migratory movements; shearwater mortality was particularly high at 36–37°S (50%) and 39–40°S (36%). Sooty shearwater mortality presented a very high spatial overlap (93%) and significant temporal correlation (0.64) with combined industrial and artisanal purse-seine fishing effort targeting on Peruvian anchovy (Engraulis ringens) and Araucanian herring (Strangomera bentincki). Our study shows when and where seabirds are more susceptible to mortality due to interactions with fisheries along the Chilean coast. This information could be used by authorities to regulate the fishing activity and focus conservation efforts to the most affected species at the appropriate spatial and temporal scales.