Black-browed Albatrosses gather behind a Uruguayan trawler deploying twin bird-scaring lines either side of the warp cable; photograph by Pablo Troncoso

Sebastián Jiménez (Laboratorio de Recursos Pelágicos, Dirección Nacional de Recursos Acuáticos, Montevideo, Uruguay) and colleagues have published in the journal Biological Conservation on reducing seabird mortality due to warp cable collisions in a demersal trawl fishery in the South Atlantic.

The paper’s abstract follows:

“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).”

Black-browed Albatrosses behind a trawler in the South Atlantic, photograph by Graham Parker

With thanks to Sebastián Jiménez.

Reference:

Jiménez, S., Páez E., Forselledo, R., Loureiro, A., Troncoso, P. & Domingo, A. 2022.  Predicting the relative effectiveness of different management scenarios at reducing seabird interactions in a demersal trawl fishery.  Biological Conservation 267.  doi.org/10.1016/j.biocon.2022.109487.

John Cooper, ACAP Information Officer, 23 February 2022

Ana Carneiro (BirdLife International, Cambridge, UK.) and colleagues have published open access in the journal Animal Conservation on studying Wandering Albatross Diomedea exulans - fishing vessel interactions with immersion loggers.

The paper’s abstract follows:

“Advances in biologging techniques and the availability of high-resolution fisheries data have improved our ability to understand the interactions between seabirds and fisheries and to evaluate mortality risk due to bycatch.  However, it remains unclear whether movement patterns and behaviour differ between birds foraging naturally or scavenging behind vessels and whether this could be diagnostic of fisheries interactions.  We deployed novel loggers that record the GPS position of birds at sea and scan the surroundings to detect radar transmissions from vessels and immersion (activity) loggers on wandering albatrosses Diomedea exulans from South Georgia.  We matched these data to remotely sensed fishing vessel positions and used a combination of hidden Markov and random forest models to investigate whether it was possible to detect a characteristic signature from the seabird tracking and activity data that would indicate fine-scale vessel overlap and interactions.  Including immersion data in our hidden Markov models allowed two distinct foraging behaviours to be identified, both indicative of Area Restricted Search (ARS) but with or without landing behaviour (likely prey capture attempts) that would not be detectable with location data alone.  Birds approached vessels during all behavioural states, and there was no clear pattern associated with this type of scavenging behaviour.  The random forest models had very low sensitivity, partly because foraging events at vessels occurred very rarely, and did not contain any diagnostic movement or activity pattern that was distinct from natural behaviours away from vessels.  Thus, we were unable to predict accurately whether foraging bouts occurred in the vicinity of a fishing vessel, or naturally, based on behaviour alone.  Our method provides a coherent and generalizable framework to segment trips using auxiliary biologging (immersion) data and to refine the classification of foraging strategies of seabirds.  These results nevertheless underline the value of using radar detectors that detect vessel proximity or remotely sensed vessel locations for a better understanding of seabird–fishery interactions.”

With thanks to Richard Phillips.

Reference:

Carneiro, A.P.B., Dias, M.P., Oppel, S., Pearmain, E.J., Clark, B.L., Wood, A.G., Clavelle, T. & Phillips, R.A. 2022.  Integrating immersion with GPS data improves behavioural classification for wandering albatrosses and shows scavenging behind fishing vessels mirrors natural foraging.  Animal Conservation doi.org/10.1111/acv.12768.

John Cooper, ACAP Information Officer, 22 February 2022

 
Short-tailed Albatross, photograph by Hiroshi Hasegawa

Nigel Brothers (Marine Ecology & Technology, Wonga Beach, Queensland, Australia) and colleagues have published in the open-access journal Marine Ornithology on using satellite imagery to count Vulnerable Short-tailed Albatrosses breeding on the Senkaku Islands.

The paper’s abstract follows:

“Accurate monitoring of vulnerable albatross populations is essential to their conservation. Herein, we explore the prospect of monitoring one particular remote albatross population with a view to promoting accurate worldwide monitoring of vulnerable albatross populations. We used very high-resolution (VHR) satellite images to count nesting Short-tailed Albatrosses Phoebastria albatrus on two islands of the Senkaku group, western North Pacific Ocean, where conventional monitoring has not occurred for 19 years due to a geopolitical territory dispute. Despite count uncertainties across rocky terrain, many birds were clearly discernible using the highest resolution image available of Minami-kojima. The result was a count of 132 (109­-162) nesting pairs in the 2020/21 breeding season (the timing of the count indicates the presence of nesting birds); this compares to a count of 52 when the population was last surveyed in 2002. On Kita-kojima, no birds were counted in images available for the 2019/20 and 2020/21 breeding seasons; one bird (a chick) was counted in 2002. If accurate, these counts are inconsistent with existing projections of increasing abundance of this species at the Senkakus (190 breeding pairs by 2018/19). Based on our findings, we suggest that reliable satellite image-based counts, independent of ground verification, is an achievable goal for albatrosses. Images must be of the highest possible resolution, with angle and timing optimized appropriately for the breeding site.  There is a need for standardization of specific procedures and methodologies, a task that is well-suited to The Working Group of the Agreement on the Conservation of Albatrosses and Petrels.”

WorldView-3 30-cm resolution satellite image of Minami-kojima and Kita-kojima, Senkaku Islands, western North Pacific Ocean on 27 November 2020, with inset showing primary (P) and secondary (S) nest count areas of Short-tailed Albatrosses; ©2020 Maxar Technologies

Read about the taxonomic status of the Senkaku Short-tailed Albatrosses here.

With thanks to Nigel Brothers.

Reference:

Brothers, N., Bone, C. & Wellbelove, A. 2022.  Albatross population monitoring using satellite imagery, a case study:. Marine Ornithology 50: 7-12.

John Cooper, ACAP Information Officer, 21 February 2022

 
A Southern Giant Petrel on Gough Island, watercolour by Susanne Durchholz, after a photograph by Michelle Risi

Peter Ryan (FitzPatrick Institute of African Ornithology, University of Cape Town, Rondebosch, South Africa) and Stefan Oppel (RSPB Centre for Conservation Science, Cambridge, UK) have published in the open-access journal Marine Ornithology on the winter presence of Southern Giant Petrels Macronectes giganteus on Gough Island.

The paper’s abstract follows:

“Southern Giant Petrels Macronectes giganteus are partial migrants, but the proportion of adult males and females that visit the colony on Gough Island during winter is poorly defined. A better understanding of winter colony attendance is important to predict the possible impact of non-target mortality during restoration efforts involving poison baiting to eradicate introduced mammals. We repeatedly checked the individual identity of all giant petrels attending the largest breeding colony on Gough Island for rings during April-May 2021. Although the maximum number of individually identifiable ringed adults in a single check was 202, overall, 353 ringed adults were recorded, including almost 90% of the individuals that bred in 2020. Males were more likely to be present than females, but the ratio of males to females decreased from the end of April (3.24:1) to the latter half of May (1.25:1). Many birds were paired with their previous breeding partners by the end of May, despite egg laying not starting until late August. Our observations indicate that most adult Southern Giant Petrels are present at their breeding colonies on Gough Island 3-4 months before breeding, and are thus potentially susceptible to non-target poisoning during mammal eradication operations.’

Reference:

Ryan, P.G. & Oppel, S. 2022.  Winter colony attendance by adult Southern Giant Petrels Macronectes giganteus: implications for rodent eradications.  Marine Ornithology 50: 1-4.

John Cooper, ACAP Information Officer, 18 February 2022