Puffinus Gravis Research Articles

Aggregative responses of marine predators to a pulsed resource.

Pulsed resources resulting from animal migrations represent important, transient influxes of high resource availability into recipient communities. The ability of predators to respond and exploit these large increases in background resource availability, however, may be constrained when the timing and magnitude of the resource pulse vary across years. In coastal Newfoundland, Canada, we studied aggregative responses of multiple seabird predators to the annual inshore pulse of a key forage fish species, capelin (Mallotus villosus). Seabird aggregative responses to fish biomass were quantified from weekly hydroacoustic and seabird surveys during July-August within an annually persistent foraging area (10 km2) associated with a cluster of capelin spawning sites across 10 years (2009-2010, 2012, 2014-2020). Seabird predators included breeding members of the families Alcidae (Common Murres Uria aalge, Razorbills Alca torda, Atlantic Puffins Fratercula arctica) and Laridae (Great Black-backed Gulls Larus marinus, American Herring Gulls L. argentatus smithsonianus) and Northern Gannets Morus bassanus, along with non-breeding, moulting members of the Family Procellariidae (Sooty Shearwaters Ardenna griseus, Great Shearwaters A. gravis). The inshore migration of spawning capelin resulted in 5-619 times (mean ± SE, 146 ± 59 times) increase in coastal fish biomass along with a shift towards more, larger and denser fish shoals. Within years, seabird abundance did not increase with inshore fish biomass but rather peaked near the first day of spawning, suggesting that seabirds primarily respond to the seasonal resource influx rather than short-term variation in fish biomass. Across years, the magnitude of the seabird aggregative response was lower during low-magnitude resource pulse years, suggesting that predators are unable to perceive low-magnitude pulses, avoid foraging under high competitor densities, and/or shift dietary reliance away from capelin under these conditions. The seabird response magnitude, however, was higher when the resource pulse was delayed relative to the long-term average, suggesting that predators increase exploitation during years of minimal overlap between the resource pulse and energetically demanding periods (e.g. breeding, moulting). This long-term study quantifying responses of multiple predators to a pulsed resource illustrates the ability of natural systems to tolerate natural and human-induced disturbance events.

Little change in plastic loads in South Atlantic seabirds since the 1980s

Despite growing concern about the large amounts of waste plastic in marine ecosystems, evidence of an increase in the amount of floating plastic at sea has been mixed. Both at-sea surveys and ingested plastic loads in seabirds show inconsistent evidence of significant increases in the amount of plastic since the 1980s. We use 3727 brown skua Catharacta antarctica regurgitations, each containing the remains of a single seabird, to monitor changes in plastic loads in four seabird taxa breeding at Inaccessible Island, Tristan da Cunha in nine years from 1987 to 2018. Frequency of occurrence in plastic ingestion and types were compared across four near-decadal time periods (1987–1989; 1999–2004; 2009–2014 and 2018) while loads were compared among years. The number and proportions of industrial pellets among ingested plastic decreased consistently over the study period in all four taxa, suggesting that industry initiatives to reduce pellet leakage have reduced the numbers of pellets at sea. Despite global plastic production increasing more than four-fold over the study period, there was no consistent increase in the total amount of ingested plastic in any species. Plastic loads in great shearwaters Ardenna gravis, which spend the austral winter in the North Atlantic Ocean, increased in 2018, but the proportion of shearwaters containing plastic decreased. We conclude that the density of plastic floating at sea has not increased in line with global production over the last 30 years.

Herpesviruses in migrating procellariforms, northeastern Brazil

Seabirds are one of the most threatened avian groups. Viruses, including herpesvirus, represent considerable threats to marine avifauna. Herein, our goal was to survey herpesvirus in Procellariiformes that stranded in Brazil between June and July 2021. We analyzed 12 Cory's shearwaters (Calonectris borealis), two Great Shearwaters (Ardenna gravis, syn. Puffinus gravis) and one Yellow-nosed Albatross (Thalassarche chlororynchos) found in an unusual mortality event in Bahía state, northeastern Brazil. After necropsy, selected tissue samples were tested for herpesvirus using a broad-range nested PCR. Overall, 20% (3/15) of the birds were herpesvirus-positive, i.e., two Cory's Shearwaters and one Great Shearwater. One alphaherpesvirus sequence type was identified in each shearwater species, classified into the genus Mardivirus. This study describes two likely novel herpesviruses in shearwaters, contributing to the currently very scarce data regarding infectious agents in Procellariiformes. Further studies are necessary to evaluate the presence and characteristics of herpesvirus in Procellariiformes, and the presence (or not) of related disease in order to understand the epidemiology of this infectious agent and eventually contribute to the conservation of this endangered seabird group.

Regurgitated skua pellets containing the remains of South Atlantic seabirds can be used as biomonitors of small buoyant plastics at sea

Using seabirds as bioindicators of marine plastic pollution requires an understanding of how the plastic retained in each species compares with that found in their environment. We show that brown skua Catharacta antarctica regurgitated pellets can be used to characterise plastics in four seabird taxa breeding in the central South Atlantic, even though skua pellets might underrepresent the smallest plastic items in their prey. Fregetta storm petrels ingested more thread-like plastics and white-faced storm petrels Pelagodroma marina more industrial pellets than broad-billed prions Pachyptila vittata and great shearwaters Ardenna gravis. Ingested plastic composition (type, colour and polymer) was similar to floating plastics in the region sampled with a 200 μm net, but storm petrels were better indicators of the size of plastics than prions and shearwaters. Given this information, plastics in skua pellets containing the remains of seabirds can be used to track long-term changes in floating marine plastics.

Great Shearwater (Ardenna gravis) attendance at commercial fisheries in the Argentine economic fishing zone

Great Shearwater (Ardenna gravis) attendance at commercial fisheries in the Argentine economic fishing zone

Long-term changes in petrel populations on Inaccessible Island, Tristan da Cunha, inferred from the diet of Brown Skuas Stercorarius antarcticus

Petrels that breed in burrows and return to their colonies after dark are among the most poorly studied seabirds. Brown Skuas Stercorarius antarcticus (family Stercorariidae) are major predators of burrowing petrels at many seabird breeding islands in the Southern Ocean, so monitoring the diet of skuas can provide insights into petrel population trends. Regurgitated pellets and other prey remains indicate that petrels comprise 94% (monthly range 91–97%) of all prey items in the pellets and other prey remains on Inaccessible Island, Tristan da Cunha. Other seabirds (0.7%), land birds (1.0%), subantarctic fur seals Arctocephalus tropicalis (0.5%) and marine animals (3.5%) make up the remainder of the Brown Skua diet. At least 12 species of petrels are eaten, including two species that are not known to breed on Inaccessible Island, but five taxa comprised over 98% of all petrels eaten: Fregetta storm petrels (44%), White-faced Storm Petrels Pelagodroma marina (23%), Broad-billed Prions Pachyptila vittata (21%), Great Shearwaters Ardenna gravis (6%) and Common Diving Petrels Pelecanoides urinatrix (5%). Pellets containing 2 or 3 avian prey items (15% of pellets) were more likely to contain conspecifics than heterospecifics, indicating either local differences in prey distribution or individual dietary specialisation. The prey composition changed seasonally linked to the phenology of the prey species, with White-faced Storm Petrels more common in the skua diet in spring, and Fregetta storm petrels in summer. Fur seals and Great Shearwaters have become more important in the skua diet, reflecting known or suspected increases in the populations of these species on the island, whereas the populations of Common Diving Petrels and Subantarctic Shearwaters Puffinus elegans may have decreased. Modal tarsal length of Fregetta storm petrels changed from 37 mm in 1987/89 to 39 mm in 2009, suggesting a possible increase of F. tropica relative to F. grallaria in the skua diet. However, overall there has been little change in the diet of Brown Skuas on this island over the last four decades.

Interspecific variability in plastic ingested by Procellariiformes off the Uruguayan coast

We assessed the interspecific variability in plastic ingested by albatrosses and petrels using bycaught birds from fisheries of the Southwest Atlantic. From 107 stomachs examined, 4.17 % of the albatrosses and 62.86 % of the petrels contained plastics. Macronectes halli and Ardenna gravis had 100 % of occurrence. They were followed by Procellaria conspicillata (75 %), Procellaria aequinoctialis (47.62 %), T. melanophris (4.35 %) and T. chlororhynchos (0 %). The most common groups of plastics by size, type and color, were mesoplastics (5–20 mm), user plastics and white-clear items, respectively. Larger species tend to ingest larger items with greater surfaces. Together with evidence from other studies, our results indicate that interspecific differences in the occurrence and the dimensions of plastics appear to be associated with digestive tract morphology, foraging techniques, body size, interaction with fishing vessels, and with the availability of plastics at the sea surface.

Ecological risk assessment of a pelagic seabird species in artisanal tuna fisheries

Abstract Fishery bycatch is a serious threat to several protected, endangered, and threatened species (PETs), requiring urgent action to develop and implement conservation measures. This study performs an Ecological Risk Assessment for the Effects of Fishing (ERAEF) using a spatially and temporally Productivity–Susceptibility Analysis (PSA) to calculate the potential risk to great shearwaters (Ardenna gravis) from direct interaction with the metiers of the artisanal tuna fishing fleet at the Bay of Biscay (baitboats and trollers). The PSA incorporates productivity attributes based on the Fecundity Factor Index; and susceptibility attributes calculated from the species spatio-temporal abundance patterns obtained developing density surface models and distribution and intensity of fishing activity based on pooled Vessel Monitoring System and logbook data. The PSA shows an overall moderate risk to great shearwaters by the artisanal tuna fishery also revealing that baitboats are less risky than trollers (risk score of 3.12 ± 0.09 and 2.70 ± 0.05, respectively). Spatially, the likelihood of presence of high potential risk areas was associated with prey availability for both the PET and the commercial fish species. The systematic, repeatable, and standardized ERAEF followed in this study can be used to advice for ecosystem-based fisheries management to improve management measures for reducing bycatch of PETs around the world.

Age-Related Interactions with Wind During Migration Support the Hypothesis of Developmental Learning in a Migrating Long-Lived Seabird

Wind patterns shape migratory pathways and detours of many procellariiform bird species that seasonally migrate between hemispheres. These seabirds are long-lived, and the period of immaturity is presumed to be a time of development and learning the environment, specifically how to use wind to their advantage. We assess how wind encountered by individual Great Shearwaters (Ardenna gravis) varies along the migration journey and compare responses between presumed mature and immature birds (early and late, respectively) in southbound migration and mature birds in northbound migration. We analyze modeled Argos locations from 71 individual tracks of migratory Great Shearwaters with concurrent U (East/West) and V (North/South) wind components. Migration in seabirds is well studied, but there is limited quantitative work measuring individual birds directly interacting with wind and their associated changes in flight behavior during migration. We show that Great Shearwaters made optimal use of winds, and that different age groups made decisions that exposed them to different wind constraints. Overall, Great Shearwaters derived positive responses from wind under most conditions and did not rely on a drifting strategy, which would be suggested if wind effect (difference between ground and airspeed) was predominantly positive during migrations. Instead, they appeared to use a compensating strategy to achieve an acceptable course and speed. The difference we observed in migration phenologies suggests that by migrating later, immature birds might travel the path of least resistance and experience flight conditions that are less risky furthering their ability to withstand a variety of wind conditions encountered later in life as done by adults, which migrate earlier and are subject to more variable flight conditions. We conclude that like other procellariiforms, a longer period of sexual maturity is required to enhance flight performance and mediate energy expenditure through experiential learning and increased fitness.

Exploring the Use of Seabirds as a Dynamic Ocean Management Tool to Mitigate Anthropogenic Risk to Large Whales

Vessel strike and entanglement in fishing gear are global threats to large whales. United States management actions to reduce human-induced serious injury and mortality to large whales have been inadequate, partially due to static, spatial protection schemes that fail to adjust to distribution shifts of highly mobile animals. Whale conservation would benefit from dynamic ocean management, but few tools exist to inform dynamic approaches. Seabirds are often found in association with whales and can be tagged at lower cost and in higher numbers than whales. We explored the use of satellite-tagged seabirds (great shearwaters) as dynamic ocean management tools for near real-time identification of habitats where humpback and North Atlantic right whales aggregate, potentially increasing anthropogenic risk. We identified shearwater habitat use areas in the Gulf of Maine with 50% kernel density utilization distributions at yearly, monthly, and weekly scales using satellite-telemetry data from 2013-2018. We quantified overlap using whale sightings and whale satellite telemetry data at two spatial scales: Stellwagen Bank National Marine Sanctuary and the Gulf of Maine. Within the sanctuary, shearwaters overlapped with >50% of humpback sightings in 4 of 6 (67%) years, 15 of 23 (65%) months, and 50 of 89 (56%) of weeks. At the Gulf of Maine scale, shearwater use areas overlapped >50% of humpback sightings in 5 of 6 years (83%) and 16 of 22 (73%) months, and encompassed humpback 50% utilization distributions (based on satellite telemetry) in 2 of 3 (66%) years and 7/12 (58%) months analyzed. Overlap between shearwaters and right whales was much lower, with >50% overlap in only 1 of 6 (17%) years and 3 of 23 (13%) months. These initial results demonstrate that satellite-tagged shearwaters can be indicators of humpback whale habitat use in both space and time. With further study, tagged shearwaters may provide near-real time information necessary to operationalize dynamic management to mitigate human impacts on humpback whales.

Notes on the seabirds of Gough Island and at sea between Gough and Cape Town, March–June 2021

Relatively little has been reported about the seabirds of Gough Island, central South Atlantic Ocean, from autumn and winter. We report ad hoc observations on the abundance, phenology and moult of seabirds at Gough Island from March to June 2021, and during the voyages between the island and Cape Town, South Africa. At least 43 species of seabirds were recorded: 1 penguin, 8 albatrosses, 5 southern and 1 northern storm petrel, 22 petrels and shearwaters, 1 gannet, 3 terns and 2 skuas. The results are presented as an annotated species list as well as a daily log of species for the voyages to and from the island. More species were seen per day at sea in June than in March, but fewer individuals were recorded in oceanic waters, mainly due to the large numbers of Great Shearwaters Ardenna gravis in March.

Moult chronology and strategies of sympatric Great (Ardenna gravis) and Sooty (A. grisea) Shearwaters based on stable isotope analysis

Moult is an energetically demanding period, during which flight may be impaired and foraging ranges may become constrained. During the non‐breeding period, GreatArdenna gravisand SootyArdenna griseaShearwaters migrate from South Atlantic breeding colonies to aggregate at North Atlantic feeding grounds. We investigated whether both shearwater species used coastal Newfoundland, Canada, as a moulting area and used stable isotope ratios (δ15N, δ13C) of recently moulted primary feathers (P1, P5, P10) to infer moult location/diet for both species. Moult scores indicated that both species finished their moult (i.e. P6–10) in coastal Newfoundland, which was further corroborated with similar stable isotope ratios for Great (δ15N = 15.17 ± 1.13‰; δ13C = −18.66 ± 0.54‰) and Sooty Shearwaters (15.54 ± 0.74‰; −18.43 ± 0.78‰); however, Sooty Shearwater moult was more advanced relative to that of Great Shearwater. In contrast, isotopic ratios of P1 and P5, which were grown before arriving in coastal Newfoundland, differed between and within species, suggesting divergent locations/diet during early moult. For Great Shearwaters, P1/P5 isotopic ratios were more variable (broader niche breadth) than P10, suggesting that some individuals started moulting in the South Atlantic prior to trans‐equatorial migration, whereas others start moulting in the North Atlantic Ocean. Sooty Shearwaters had two distinct groupings of either higher or lower δ15N in P1/P5, suggesting that individuals began moulting either on the Newfoundland Shelf or further offshore based on comparisons to reference shearwater feathers grown in known locations. These findings illustrate distinct locations and/or diets at the start of primary feather moult, both within and between species, but diets converged when aggregated together at the end of moult in coastal North America, where growing feathers of both species were sampled. More importantly, we identified an important area for both Sooty and Great Shearwaters to complete their moult in coastal Newfoundland. Protecting this moulting area would minimize disturbance and the impacts of threats (e.g. by‐catch) to both species during this energetically demanding period. The area has been suggested previously to be an important candidate area for protection due to annually persistent prey aggregations that can be spatiotemporally delimited based on specific prey habitat requirements.

Two new species of nasal mites of the genus Rhinonyssus (Acari, Mesostigmata, Rhinonyssidae) from shearwaters

Nasal mites of the family Rhinonyssidae are parasites living in the respiratory system of birds. To date there were no record of these mites from representatives of the order Procellariiformes, a numerous grouping of exclusively marine birds that includes albatrosses, petrels, storm-petrels and shearwaters. The paper describes two new species of the genus Rhinonyssus from shearwaters (Procellariidae) found on various shores of Brazil: Rhinonyssus borealis sp. nov. from Calonectris borealis (Cory’s shearwater) and R. procellaricus sp. nov. from Puffinus puffinus (Manx shearwater) and Ardenna gravis (Great shearwater). Both described mites are characterized by a large elliptical body and a relatively large and strongly sclerotized with the well-developed caudal extension. Rhinonyssus borealis sp. nov. and R. procellaricus sp. nov. are similar in their general appearance to each other but differ in the size of idiosoma, shape of podosomal and sternal shields and leg chaetotaxy.

Birds of a feather eat plastic together: high levels of plastic ingestion in Great Shearwater adults and juveniles across their annual migratory cycle.

Limited work to date has examined plastic ingestion in highly migratory seabirds like Great Shearwaters (Ardenna gravis) across the their entire migratory range, although this species is prone to ingest plastic as a wide-ranging procellariiform. We examined 217 Great Shearwaters obtained from 2008-2019 at multiple locations spanning their yearly migration cycle across the Northwest and South Atlantic to assess accumulation of ingested plastic as well as trends over time and between locations. A total of 2,328 plastic fragments were documented in the ventriculus portion of the gastrointestinal tract, with an average of 9 plastic fragments per bird. The mass, count, and frequency of plastic occurrence (FO) varied by location, with higher plastic burdens but lower FO in South Atlantic individuals from the breeding colonies. No fragments of the same size or morphology were found in the primary forage fish prey, the sand lance, (Ammodytes spp., n = 202) that supports Great Shearwaters in Massachusetts Bay, USA, suggesting the birds directly ingest the bulk of their plastic loads rather than accumulating via trophic transfer. Fourier-transform infrared spectroscopy indicated that low- and high-density polyethylene were the most common polymers ingested, within all years and locations. Individuals from the South Atlantic contained a higher proportion of larger plastic items and fragments compared to juveniles and non-breeding adults from the NW Atlantic, possibly due to increased use of remote, pelagic areas subject to reduced inputs of smaller, more diverse, and potentially less buoyant plastics found adjacent to coastal margins. Different signatures of polymer type, size, and category between similar life stages at different locations suggests rapid turnover of ingested plastics commensurate with migratory stage and location, though more empirical evidence is needed to ground-truth this hypothesis. This work is the first to comprehensively measure the accumulation of ingested plastics by Great Shearwaters over the last decade and across multiple locations spanning their yearly trans-equatorial migration cycle, and underscores their utility as sentinels of plastic pollution in Atlantic ecosystems.

The summer distribution, habitat associations and abundance of seabirds in the sub-polar frontal zone of the Northwest Atlantic

Biological production in the oceanic zone (i.e. waters beyond the continental shelves) is typically spatially patchy and strongly seasonal. In response, seabirds have adapted to move rapidly within and between ocean basins, making them important pelagic consumers. Studies in the Pacific, Southern and Indian Oceans have shown that seabirds are relatively abundant in major frontal systems, with species composition varying by water mass. In contrast, surprisingly little was known about seabird distribution in the oceanic North Atlantic until recent tracking showed that relative abundance and diversity peak in the Sub-polar Frontal Zone, west of the Mid-Atlantic Ridge, now proposed as a Marine Protected Area. However, absolute seabird abundance, distribution, age and species composition, and their potential environmental drivers in the oceanic temperate NW Atlantic remain largely unknown. Consequently, we systematically surveyed seabirds and environmental conditions across this area by ship in June 2017, then modelled the density of common species as functions of environmental covariates, validating model predictions against independent tracking data. Medium-sized petrels (99.8%), especially Great Shearwaters (Ardenna gravis, 63%), accounted for the majority of total avian biomass, which correlated at the macroscale with net primary production and peaked at the sub-polar front. At the mesoscale, the density of each species was associated with sea surface temperature, indicating zonation by water mass. Most species also exhibited scale-dependent associations with eddies and fronts. Approximately 51, 26, 23, 7 and 1 % of the currently estimated Atlantic populations of Cory's Shearwaters (Calonectris borealis), Great Shearwaters, Sooty Shearwaters (A. grisea), Northern Fulmars (Fulmarus glacialis) and Leach’s Storm-petrels (Oceanodroma leucorhoa) occurred in the area during our survey, many of which were undergoing moult (a vital maintena nce activity). For some species, these estimates are higher than suggested by tracking, probably due to the presence of immatures and birds from untracked populations. Our results support the conclusion that MPA status is warranted and provide a baseline against which future changes can be assessed. Moreover, they indicate potential drivers of seabird abundance and diversity in the oceanic zone of the North Atlantic that should be investigated further.

PATHOLOGY OF NORTHERN FULMARS (FULMARUS GLACIALIS) AND SHEARWATERS BEACHED ON SABLE ISLAND, NOVA SCOTIA, CANADA

Marine birds are frequently found dead on beaches, either from natural or from anthropogenic causes. Complete necropsies of those carcasses can provide valuable information, particularly for pelagic species, such as Northern Fulmars (Fulmarus glacialis) and shearwaters, which come to land only to breed and for which information on diseases that may affect them is, therefore, sparse. Between 2000 and 2012, 315 carcasses of four species of Procellariiformes (173 Northern Fulmars, 89 Great Shearwaters [Ardenna gravis], 50 Sooty Shearwaters [Ardenna grisea], and three Cory's Shearwaters [Calonectris diomedea]) were collected on Sable Island, Nova Scotia, Canada, an isolated island near the edge of the continental shelf. A complete necropsy, including examination for the presence of ingested plastic, was performed on all carcasses. Most (70%) of these birds were immature. The cause of death was undetermined in 22% (n=70) of the birds: 36% (62/173) of the Northern Fulmars, 4% (4/89) of the Great Shearwaters, 6% (3/50) of the Sooty Shearwaters, and 33% (1/3) of the Cory's Shearwaters. Emaciation was considered the primary cause of death in 91% of the remaining 245 birds: 87% (97/111) of the Northern Fulmars, 92% (78/85) of the Great Shearwaters, 100% (47/47) of the Sooty Shearwaters, and 100% (2/2) of the Cory's Shearwaters. Notable primary causes of death other than emaciation included mycobacteriosis and neoplasia in Northern Fulmars and transmural parasitic proventriculitis in Great Shearwaters. For Northern Fulmars, nutritional condition (as determined semiquantitatively) was compared with other parameters. Birds in good nutritional condition had heavier body mass and flight muscle mass than those in poor nutritional condition (P<0.01). More adults were in poor nutritional condition than expected by chance (91%; χ2=8.23, P<0.01), whereas only 57% of immature birds were in poor condition. There was no relationship between nutritional condition and sex or mass of ingested plastic. Our study provides information on some previously unsuspected health threats in Procellariiformes.

Heavy Metals Content in Great Shearwater (Ardenna Gravis): Accumulation, Distribution and Biomarkers of Effect in Different Tissues.

The purpose of this study was to explore the usefulness of Great Shearwater (Ardenna gravis) as a bioindicator for biomonitoring programs for metal pollution. Three different metals were analysed in liver, kidney, and feathers, including cadmium, lead, and zinc. Glutathione-S-transferase, malondialdehyde, reduced glutathione, and catalase were assessed as oxidative stress biomarkers. Sex-related trends in metal accumulation also were evaluated. In liver and kidney, the mean concentrations of Zn (146.1 ± 5.14 and 108 ± 2.70mg/kg, respectively) and Pb (0.19 ± 0.01 and 0.13 ± 0.01mg/kg, respectively) in A. gravis were generally comparable to values reported in other studies. However, animals presented slightly higher concentrations of Cd (9.67 ± 0.65 in liver and 17.41 ± 0.84mg/kg in kidney) than those reported in the same species sampled in Southern Atlantic waters. The slightly higher levels of Cd found in this study compared with other studies are probably affected by the location in Northern Atlantic waters (with different diet intake). In feathers, levels of Zn (70.70 ± 1.76mg/kg) were lower than in other Ardenna shearwaters, whereas higher levels were found for Cd (0.16 ± 0.01mg/kg) and Pb (0.84 ± 0.06mg/kg). The lack of differences found between males and females could be influenced by the migration status, because both sexes stay in similar physiological conditions, with no laying eggs. Levels found in the feathers of the present study were related to concentrations in internal tissues below those which cause adverse effects in birds. Thus, feathers would appear as a potential noninvasive tool for metals biomonitoring in seabirds, because it is possible to quantify them. Baseline data of oxidative stress levels have been reported, both in liver and kidney, presenting no correlations with the levels of metals in these tissues. The low internal metal levels and the lack of correlations between oxidative stress metrics suggest a low risk of the environmental concentrations for seabirds.

Plastic additives and legacy persistent organic pollutants in the preen gland oil of seabirds sampled across the globe

Plastic pollution, and its associated impacts on marine fauna due to chemical contamination, is an area of growing global concern. We analyzed 145 preen gland oil samples from 32 seabird species belonging to 8 families with different foraging habits and life history strategies from around the world for plastic additives and legacy persistent organic pollutants. The additives included two brominated flame retardants (decabromodiphenyl ether, BDE209; decabromo diphenyl ethane, DBDPE) and six benzotriazole UV stabilizers (BUVSs; UVP, UV326, UV329, UV328, UV327, and UV234). Polychlorinated biphenyls (PCBs) and organochlorine pesticides (Dichlorodiphenyltrichloroethane and its metabolites: DDTs and hexachlorocyclohexane: HCHs) were detected ubiquitously. High concentrations of PCBs (up to 20,000 ng/g-lipid) were observed in the seabirds from higher-trophic level taxa. These patterns can be attributed to PCB exposure via their diet and associated biomagnification. DDT concentrations showed strong positive correlations with PCB concentrations, suggesting that DDTs in seabirds are also a result of diet and biomagnification. Plastic additives were detected sporadically as BDE209 and DBDPE were detected in 16 seabirds from 10 species (range: 3–379 ng/g-lipid) and BUVSs were detected in 46% (67) of the examined individuals (range: 2–7,055 ng/g-lipid). UV stabilizers were more frequently detected than flame retardants because UV stabilizers are more widely applied to plastic products. None of the plastic additives were correlated to the presence of PCBs, nor were they explained by the foraging area or trophic level. High concentrations of additives were detected in the species with high levels of plastic in their digestive tracts. In some of these species, such as Hawaiian petrels (Pterodroma sandwichensis) from Hawaii and flesh-footed shearwaters (Ardenna carneipes) from Western Australia, plastics were directly observed in the stomach. For other species, including great shearwaters (Ardenna gravis) from Gough Island, blue petrels (Halobaena caerulea) from Marion Island, and black-footed and Laysan albatrosses (Phoebastria nigripes and P. immutabilis) from Hawaii, plastic ingestion has been documented in literature. These patterns can be explained if the additives are mainly from ingested plastics rather than diet. The detection of BFRs and BUVSs demonstrated that a significant proportion of the examined seabirds accumulated chemicals from ingested plastics.

Incidental capture of seabirds in Argentinean side-haul trawlers

SummaryBetween April 2008 and July 2015, we conducted a total of 18 trips on five different side-haul trawlers fishing within the Argentine Exclusive Economic Zone, monitoring 486 hauls. We observed 100% of the hauls and monitored trawl cables for 136.7 hours, about 5% of the trawl effort, to identify the levels of seabird bycatch from net entanglements and collisions with trawl cables. A total of 35 net entanglements of White-chinned Petrels Procellaria aequinoctialis, Great Shearwaters Ardenna gravis, Black-browed Albatrosses Thalassarche melanophris and Southern Royal Albatross Diomedea epomophora were recorded, all of which occurred during the autumn and winter. Additionally, 656 seabird collisions against trawl cables were recorded including 39 heavy, 96 medium and 521 light. Further, we recorded nine Black-browed Albatrosses and two Great Shearwaters potentially dead. Although in the study fishery the number of deaths in the trawl cables could surpass the number of birds incidentally killed in nets, the mortality rate caused by the latter type of interaction far exceeds those observed in nets from other trawl fisheries operating in the Patagonian Shelf. Fortunately, 26% of the seabirds entangled in the net were recovered and released alive, which indicates that awareness and training in safe bird handling and release may improve captured seabird survival rates. The main objectives of this work is to highlight a little-studied source of seabird mortality by entanglement, to generate discussion on potential technical mitigation measures for side-haul trawl fisheries, and to propose crew training in safe handling and release of seabirds as an immediate mitigation measure.

High collocation of sand lance and protected top predators: Implications for conservation and management

AbstractSpatial relationships between predators and prey provide critical information for understanding and predicting climate‐induced shifts in ecosystem dynamics and mitigating human impacts. We used Stellwagen Bank National Marine Sanctuary as a case study to investigate spatial overlap among sand lance (Ammodytes dubius), a key forage fish species, and two protected predators: humpback whales (Megaptera novaeangliae) and great shearwaters (Ardenna gravis). We conducted 6 years (2013–2018) of standardized surveys and quantified spatial overlap using the global index of collocation. Results showed strong, consistent collocation among species across seasons and years, suggesting that humpback whales and great shearwater distributions are tightly linked to sand lance. We propose that identifying sand lance habitats may indicate areas where humpbacks and shearwaters aggregate and are particularly vulnerable to human activities. Understanding how sand lance influence predator distributions can inform species protection and sanctuary management under present and future scenarios.