Lucas Krüger (Instituto Antártico Chileno, Punta Arenas, Chile) writes in the journal Polar Biology on trends in numbers of Southern Giant Petrels Macronectes giganteus breeding at an Antarctic site.

The paper’s abstract follows:

“In several parts of Antarctica, the information on the size of seabird populations is outdated by decades. Considering the environmental changes taking place at the Antarctic Peninsula, up-to-date information is urgently required. In this study, the breeding population of southern giant petrel (Macronectes giganteus) at Harmony Point, Nelson Island, was counted and mapped during incubation. The total number of active nests was 481, distributed mostly in small dispersed groups (< 30 nests); one single colony presented > 100 nests. Nests were distributed throughout the whole area. Current colony distribution was similar to the ones reported previously. The current number of nests is similar to those reported since 2005, and also for early counts in the 1965 and 1989s. However, current numbers were almost half of those counted in the 1997. The apparent increases in the number of southern giant petrels by 1997 was attributed to prohibiting tourism visits to the area (giant petrels are sensitive to human disturbance), but causes of the following decrease are unknown. This highlights the need for updated information in order to understand which factors are responsible for trends in Antarctic seabird populations.”

Southern Giant Petrels breeding in Antarctica, photograph from Maria Virginia Petry & Uwe Horst Schulz.

Reference:

Krüger, L. 2019.  An update on the Southern Giant Petrels Macronectes giganteus breeding at Harmony Point, Nelson Island, Maritime Antarctic Peninsula.  Polar Biology doi.org/10.1007/s00300-019-02504-5.

John Cooper, ACAP Information Officer, 28 May 2019

BirdLife South Africa is tackling the problem of designing bird-scaring lines (BSLs) for small (<35-m) longliners in the domestic fishery that are cheap, easy to deploy and less likely to get entangled than those made for deployment on larger vessels.  Use of BSLs is mandatory in South African longline (and trawl) fisheries.

Andrea Angel and Reason Nyengera of BirdLife South Africa’s Albatross Task Force (ATF) write in a recent blog

“Bird-scaring lines (BSLs) have become the primary and most commonly prescribed seabird bycatch mitigation measure in longline fisheries worldwide.  These are usually composed of a backbone section, colourful streamers and a drag section or towing device. They are extremely effective at reducing seabird bycatch since they scare foraging birds away from the “danger zone” in which baited hooks are close to the surface and easily accessible.  However, since BSLs have primarily been developed for and on large vessels, there is an urgent need to adapt them to the reality of small vessels and the fishing gear and conditions found on these. In South Africa our domestic longline fleets are largely under 35 m and while some skippers report successfully deploying BSLs on a regular basis, others have reported concerns relating to difficulties with deployments in bad weather conditions, entanglements with fishing gear, lack of high attachment points and unnecessarily cumbersome and bulky BSLs.”

A South African bird-scaring line is deployed behind a demersal trawler, keeping two Black-browed Abatrosses (and a Cape Gannet) away from the warp

BirdLife South Africa’s ATF has been working for over a decade with the Ocean View Association for Persons with Disabilities (OVAPD), which is based in the southern part of the Cape Peninsula near Cape Town, to manufacture BSLs of two different designs to keep birds away from demersal trawl cables and from longline fishing hooks on South Africa vessels.  The partnership brings meaningful employment to a disadvantaged community (click here).  OVAPD members will now be trained to manufacture the new design of BSLs, before they can be used commercially. Read earlier ALN postings on OVAPD here.

OVAPD members make a bird-scaring line

OVAPD members with Andrea Angel, Albatross Task Force Leader in South Africa (kneeling left)

Photographs from BirdLife South Africa's Albatross Task Force

BirdLife International and ACAP have co-produced a series of 15 Seabird Bycatch Mitigation Factsheets which describe the range of potential mitigation measures available to reduce seabird bycatch in longline and trawl fisheries, including different types of bird-scaring lines.

With thanks to Andrea Angel.

John Cooper, ACAP Information Officer, 27 May 2019

Morgan Gilmour (Ocean Sciences Department, University of California, Santa Cruz, California, USA) and colleagues have published in the journal Ecological Indicators on mercury and prolactin levels in Flesh-footed Shearwaters Ardenna carneipes (globally Near Threatened) and Great-winged Petrels Pterodroma macroptera.

The paper’s abstract follows:

“Marine predators are frequently exposed to contaminants through diet, and thus contaminants like mercury have the potential to be used as tracers of foraging ecology. Mercury’s neurotoxic and endocrine-disrupting effects can have far-ranging consequences for both individuals and populations, and thus mercury concentrations could also be indicative of wildlife health. Because blood samples are relatively non-invasive and easy to obtain in seabird colonies, we investigated whether blood-based mercury concentrations were representative of foraging ecology and breeding hormone concentrations in seabirds. Blood-based mercury carbon and nitrogen stable isotopes, and the reproductive hormone, prolactin, were sampled from two seabird species that exhibit different foraging strategies in Western Australia: Great-winged Petrels (Pterodroma macroptera) are pelagic squid-specialists whose populations are under-studied; Flesh-footed Shearwaters (Ardenna carneipes) are coastal foragers that associate with fishing vessels, and are a species listed as Vulnerable in Western Australia. Mercury was six times higher in Great-winged Petrels (geometric mean ± SE: 3.360 ± 0.180 μg g⁻¹ ww, n = 15) than Flesh-footed Shearwaters (0.554 ± 0.109 μg g⁻¹ ww, n = 12). There was a significant difference in δ¹⁵N between species, and within-species variation in δ¹³C mirrored variation in mercury concentrations, supporting the view that foraging ecology plays a central role in mercury exposure. Furthermore, Great-winged Petrels’ mercury concentrations are among the highest reported in seabirds. However, no relationship between mercury and prolactin concentrations was detected. Overall, these results demonstrate that mercury can be used as a foraging ecology tracer in these populations but may not be a good indicator of seabirds’ breeding hormones like prolactin, though mercury may affect other aspects of reproduction that we did not measure. These results may aid in future assessment of population trends in these, and other, species.

Flesh-footed Shearwater, photograph by Barry Baker

Reference:

Gilmour, M.E., Lavers, J.L., Lamborg, C., Chastel, O., Kania, S.A. & Shaffer, S.A. 2019.  Mercury as an indicator of foraging ecology but not the breeding hormone prolactin in seabirds.  Ecological Indicators 103: 248-259.

John Cooper, ACAP Information Officer, 24 May 2019

Lucía Soliño (Instituto Português do Mar da Atmosfera, Lisbon, Portugal) and colleagues have published in the journal Harmful Algae on whether harmful algal blooms can affect pelagic seabirds, such as Cory’s Calonectris borealis and Scopoli’s C. diomedea Shearwaters.

The paper’s abstract follows:

“Marine birds have been hypothesized to be underreported victims of harmful algal blooms (HABs). Toxic blooms of Pseudo-nitzschia spp., the primary amnesic toxin producer microalgae, domoic acid (DA) are known to cause massive mortalities of coastal seabirds and marine mammals around the world. However, these fatalities are only detected when birds die nearby the coastline and little is known about possible outbreaks of pelagic seabirds in oceanic areas. Here we aim to understand whether pelagic seabirds are exposed to amnesic shellfish poisoning (ASP) toxins. For this purpose, we tracked pelagic seabirds feeding on small epipelagic fish and squid, reported to be vectors of DA, which are obtained in high productivity zones where intense Pseudo-nitzschia blooms regularly occur. In particular, we tracked Cory’s (Calonectris borealis) and Scopoli’s (C. diomedea) shearwaters breeding in Gran Canaria (Canary Is.) and in Menorca (Balearic Is.) and feeding on the Canary Current region and the Catalonian coast, respectively. We sampled birds for blood at the recovery of the GPS (Global Positioning System) and analyzed it for DA determination by Liquid Chromatography coupled with Tandem Mass Spectrometry (LC–MS/MS). Among the 61 samples analyzed from Gran Canaria, and 87 from Menorca, 31 (50.8%) and 28 (32.2%) from each location presented detectable levels of DA ranging 1.0–10.6 ng mL⁻¹. This work reveals that DA can be detected at variable levels in the blood of ASP-asymptomatic shearwaters and suggests a chronic exposure of shearwaters to DA, highlighting the need for further studies on DA effects. These results are of high relevance due to the vulnerability of these marine birds, which populations are in continuous decline. Since global warming is expected to alter and increase the occurrence of HABs, marine toxins might become an additional stressor for seabirds and exacerbate the already precarious conservation status of many species.”

Scopoli's Shearwater, photograph by 'Pep' Arcos

Reference:

Soliño, L., Ferrer-Obiol, J., Navarro-Herrero, L. González-Solís, J. & Costa, P.R. 2019.  Are pelagic seabirds exposed to amnesic shellfish poisoning toxins?  Harmful Algae 84: 172-180.

John Cooper, ACAP Information Officer, 23 May 2019