Balearic Shearwater at sea, photograph by Pep Arcos

Andrés de la Cruz (University Institute of Marine Research, Cádiz University, Spain) and colleagues have published in the journal Aquatic Conservation: Marine and Freshwater Ecosystems on using spatial modelling as a tool to define the at-sea distribution of Critically Endangered Balearic Shearwaters Puffinus mauretanicus in the Gulf of Cádiz.

The paper’s abstract follows:

“1. Spatial modelling is an important research tool to improve our knowledge about the distribution of wildlife in the ocean. Using different modelling techniques (MaxEnt and a generalized linear mixed model), a predictive habitat suitability model was developed for one of the most threatened seabirds in the world: the Balearic shearwater, Puffinus mauretanicus.
2. Models were developed using a 10-year dataset from the Gulf of Cádiz (on the south-western Iberian Peninsula), a key foraging area for Balearic shearwaters during migration and the non-breeding season.
3. Predictive habitat maps strongly matched the observed distribution patterns, pointing to bathymetric features as the main modelling drivers. The species was concentrated on shallow areas (up to approximately 100 m in depth) of the continental shelf, very close to the mouth of the Guadalquivir River. In contrast with previous studies, Balearic shearwater distribution in the highly dynamic Gulf of Cádiz was not correlated with areas of high chlorophyll a concentration.
4. This lack of spatial correlation probably arises from the delay between the phytoplankton bloom and the response of the zooplankton and small fish that are preyed upon by Balearic shearwaters, which may result in important displacements of this trophic chain across the Gulf of Cádiz.
5. The analysis presented contributes to a better understanding of the spatial distribution and ecology of the critically endangered top predator in the Gulf of Cádiz and offers important information to improve management plans.”

With thanks to Barry Baker.

Reference:

de la Cruz, A., Ramos, F., Navarro, G., Cózar, A., Bécares, J. & Arroyo, G.M. 2021.  Drivers for spatial modelling of a critically endangered seabird on a dynamic ocean area: Balearic shearwaters are non-vegetarian.  Aquatic Conservation: Marine and Freshwater Ecosystems doi.org/10.1002/aqc.3542.

John Cooper, ACAP Information Officer, 06 April 2021

Short-tailed Shearweater at sea, photograph by  Kirk Zufelt

Lauren Roman (Marine Debris Research, CSIRO Oceans and Atmosphere, Hobart, Tasmania, Australia) and colleagues have published in the journal Marine Ecology Progress Series on starving Short-tailed Shearwaters Ardenna tenuirostris (Least Concern) feeding on floating pumice on their return to Australian breeding sites from trans-equatorial migration.

The paper’s abstract follows:

“Food deprivation may decrease selectivity in food; however, (1) whether animals can cross a selectivity threshold whereby they ingest non-nutritive items ('non-food') in lieu of food (engaging in pica/lithophagia), (2) their behaviour, or (3) the implications of these behaviours are not documented. By examining carcasses of seabirds that ingested pumice of known provenance prior to death, we provide insights into whether wild animals starve because they have eaten non-food, or whether they eat non-food because they are starving. We investigated ingestion of pumice and plastic in carcasses of short-tailed shearwaters Ardenna tenuirostris following a significant starvation mortality event (also known as seabird wreck), during which millions of shearwaters died along the eastern Australian coastline in 2013. We found that the stomachs of 96.5% of 172 seabirds sampled contained pumice or plastic at the time of death. We used global location sensors to track the 2013 shearwater migration and overlaid these tracks with the dispersing pumice raft from the 2012 Havre underwater volcanic eruption, Kermadec Islands, New Zealand. We determined that shearwaters in a starved state had ingested pumice 12-41 h before death, indicating that starving or food-stressed seabirds exhibit reduced prey discrimination. The provenance of the ingested plastic was not known. Ingestion of non-nutritive items has serious implications for wildlife, particularly long-lived or migrating species. Additional risk to already nutritionally compromised animals includes dietary dilution, gastric foreign body obstruction and toxicity. With a projected changing climate and increased marine pollution and over-exploitation of resources, this study has implications for the interaction of stressors, mass mortalities and exacerbation of existing threats to marine species.”

Read a popular account of the research, and access related papers by the senior author.

Reference:

Roman, L., Bryan, S., Bool, N., Gustafson, L. & Townsend, K. 2021.  Desperate times call for desperate measures: non-food ingestion by starving seabirds.  Marine Ecology Progress Series 662: 157-168.

John Cooper, ACAP Information Officer, 05 April 2021

The young Antipodean Albatross spreads its wings after release, photograph by  Dan Burgin, Wildlife Management International (WMIL)

A young Antipodean Albatross Diomedea antipodensis assigned to the gibsoni subspecies was brought in by the crew two days after landing aboard the fishing vessel Santa Rosa off the West Coast to the EcoWorld Aquarium & Wildlife Rehabilitation Centre in Picton, South Island, New Zealand.  Mike Bell of Wildlife Management International (WMIL) states on the Centre's Facebook page: “She is a young female albatross from this years breeding season. She was obviously very lethargic and weighed only 4.9 kg when she should be at about 7 kg in weight”.  Affectionately named Rosa, the albatross spent three weeks in captivity while it got back to a healthy weight, being fed on donated salmon and squid.  Following banding, the albatross was released on 29 March out at sea off the coast of Kaikoura from an Albatross Encounter Kaikoura tour vessel by Mike Bell and Dan Burgin of WMIL.

According to Wildlife Management International’s Facebook page the globally Endangered and Nationally Critical bird “spent a good amount of time bathing before swimming off.  Here’s hoping we get a band resighting at her breeding colony in years to come, but she has a long way to go still facing a myriad of threats out at sea.”  Read more here.

The Antipodean Albatross gets released at sea, photographs by Tracy McKeown, Albatross Encounter Kaikoura

A similar-looking young Antipodean Albatross “very dehydrated, very hungry and near death” on arrival was treated at New Zealand's South Island Wildlife Hospital, but died while still in care (click here).

John Cooper, ACAP Information Officer, 04 April 2021, updated 05  April 2021

Infographic from the report

Jason Jannot (Northwest Fisheries Science Center, Seattle, Washington, USA) and colleagues have produced a report that considers seabird bycatch in United States west coast fisheries from 2002 to 2018, including of the three North Pacific albatrosses.

The report’s Executive Summary follows, slightly shortened with reference citations and illustrations removed:

“The California Current marine ecosystem on the U.S. West Coast (Washington, Oregon, and California) supports a diversity of marine organisms, including seabirds. This report summarizes interactions between U.S. West Coast fisheries and seabirds, and presents estimates of fleetwide seabird bycatch—based on data from fisheries and federal observer programs—for the years 2002–18.

Lethal and nonlethal interactions, as well as sightings, are presented for six fisheries using hook-and-line gear, eight fisheries using trawl gear, and five fisheries using pot gear. In 2017, three new fisheries were added for observation by the Northwest Fisheries Science Center: the Pacific halibut hook-and-line fishery, the California ridgeback prawn trawl fishery, and the California sea cucumber trawl fishery. The Pacific halibut fishery had relatively high black-footed albatross bycatch, and the California ridgeback prawn fishery had relatively high bycatch of Brandt’s cormorant, compared to other fisheries. No birds were observed as bycatch in the California sea cucumber fishery. Recreational and tribal fisheries are not covered in this report.

A total of 47 bird species interacted with or were sighted in these fisheries over the 2002–18 period, up from 41 in the last report). Thirteen species are considered endangered, threatened, vulnerable, or near-threatened by the U.S. Endangered Species Act (ESA) or the International Union for Conservation. The remaining 34 species are not listed, or are categorized as “least concern” (i.e., not at risk).

All three North Pacific albatross species interact with these fisheries: black-footed, Laysan, and the ESA-listed short-tailed albatross. To date, only one short-tailed albatross has been observed taken by these fisheries, and the mean estimated mortality for most years is less than one individual per year. However, black-footed albatross are caught annually in a number of fisheries reported here, primarily hook-and-line fisheries. Laysan albatross have occasionally been taken by fisheries reported here, but the mortalities are few and infrequent. The estimated mean mortalities of black-footed plus Laysan albatross ranged from a low of 60.77 individuals in 2002 to a high of 139.58 individuals in 2010. The 2018 estimate, across fisheries, for black-footed and Laysan albatross was 88.69 individuals. Other birds (i.e., nonalbatross) showed a peak in mortality during 2009 of 439.76 birds taken, and the 2018 mean estimated mortality of other birds was 296.48.

Hook-and-line fisheries account for the largest number of albatrosses taken among the three gear categories (hook-and-line, trawl, pot). Over the last six years, hook-and-line fisheries accounted for 50–63% of seabird mortality, followed by trawl fisheries at 31–45%, and pot fisheries at 2–6% of bycatch. The largest number of albatross taken comes from limited entry (LE) sablefish vessels fishing hook-and-line gears. This prompted regulations requiring streamer lines on hook-and-line vessels fishing in U.S. West Coast groundfish fisheries; these were implemented in December 2015 for vessels 55 ft or longer. Beginning in January 2020, all vessels 26 ft or longer fishing with hook-and-line gear north of lat 36°N must use streamer lines during daylight hours (1 hr before sunrise to 1 hr after sunset). Alternatively, night-setting (1 hr after sunset to 1 hr before sunrise) can be used to reduce seabird bycatch on hook-and-line vessels in lieu of streamer lines.

Bycatch of nonalbatross species is generally split evenly between hook-and-line and trawl gears. Seabird mortality is likely underestimated on trawl vessels, because seabirds can be killed or injured by striking cables that exit aft of the vessel during trawling. These cables are not routinely monitored in these fisheries. Significant levels of bycatch, especially of albatross, have been recorded in similar trawl fisheries around the globe. In this report, we provide estimates of seabird mortality by cable strikes in the at-sea hake catcher–processor fleet. Pot gears appear to catch very few seabirds.

In earlier versions of this report we used ratios to estimate seabird bycatch. In the previous report), we implemented an improved method for bycatch estimation. We applied Bayesian models to estimate total bycatch and associated error for fisheries with less than 100% observer monitoring. These methods have been used with other rare bycatch species, including cetaceans, delphinids, pinnipeds, sea turtles, and sharks.). The Bayesian method better estimates uncertainty and provides fleetwide estimates even in years when no seabird mortality was recorded by fisheries observers.

In the previous report, we assumed the estimated bycatch rate, q, was constant through time. In this report, we explicitly test for constant bycatch rate. We also compare models using alternative measures of fishing effort (number of gear deployments, number of gear units, amount of landed catch) and alternative distributions of the bycatch process (Poisson versus negative binomial). The results presented here represent the optimal model when comparing these parameters.”

Reference:

Jannot, J.E., Wuest, A., Good, T.P., Somers, K.A., Tuttle, V.J., Richerson, K.E., Shama, R.S. & McVeigh, J.T. 2021. Seabird Bycatch in U.S. West Coast Fisheries, 2002–18..  U.S. Department of Commerce, NOAA Technical Memorandum NMFS-NWFSC-165.  64 pp. doi.org/10.25923/78vk-v149.

John Cooper, ACAP Information Officer, 03 April 2021