LC
Northern Gannet Morus bassanus



Justification

Justification of Red List Category
This species has a very large range, and hence does not approach the thresholds for Vulnerable under the range size criterion (Extent of Occurrence <20,000 km2 combined with a declining or fluctuating range size, habitat extent/quality, or population size and a small number of locations or severe fragmentation). The population trend appears to be increasing, and hence the species does not approach the thresholds for Vulnerable under the population trend criterion (>30% decline over ten years or three generations). The population size is very large, and hence does not approach the thresholds for Vulnerable under the population size criterion (<10,000 mature individuals with a continuing decline estimated to be >10% in ten years or three generations, or with a specified population structure). For these reasons the species is evaluated as Least Concern.

Population justification
In Europe, the breeding population is estimated to number 683,000 pairs, which equates to 1,370,000 mature individuals (BirdLife International 2015). Europe forms 75-94% of the global range, so the global population size is estimated at 1,500,000-1,800,000 mature individuals, although further validation of this estimate is needed.

Trend justification
In North America, the population trend is increasing (based on BBS/CBC data: Butcher and Niven 2007). The European population is also estimated to be increasing (BirdLife International 2015).

Distribution and population

This species is found on both sides of the Atlantic Ocean, with small numbers of individuals reaching the equator on the western and eastern side in the south, and reaching Norway in the north. Breeding sites include northern France, the United Kingdom, Ireland, Iceland, Norway and the eastern tip Quebec (Canada) (del Hoyo et al. 1992).

Ecology

This strictly marine species wanders mostly over continental selves, feeding on shoaling pelagic fish which are mostly caught by plunge-diving from large heights. It also attends trawlers and will form large congregations where food is plentiful. Breeding is highly seasonal starting between March and April, usually in large colonies on cliffs and offshore islands, but also sometimes on the mainland. Young birds will migrate to the extreme south of its range, whereas adults range less extensively but still regularly winter in the Mediterranean and Gulf of Mexico (del Hoyo et al. 1992).

Threats

Northern Gannets are consistently recorded as bycatch across fisheries in the Atlantic. It is the species most freqently killed as bycatch in fisheries assessed in Portuguese Atlantic waters, and captured at a relatively high rate in demersal longline operations, but also set-nets and purse-seines (Oliveira et al. 2015). Total estimates of numbers killed are lacking. In nearshore water off the east coast of the U.S., estimates of under 500 individuals per year suggest that population level impacts may be relatively small; however, this is derived from observers on less than 5% of fisheries within a small proportion of the range, and there is no cumulative assessment of impact (U.S. Fish and Wildlife Service 2011). Considering the observation of bycatch in fisheries across the range of the Northern Gannet (Smith and Morgan 2005, García-Barcelona et al. 2010, Oliviera et al. 2015) and evidence of increased breeding populations following the closure of Canadian gillnet fisheries (Regular et al. 2013), levels of bycatch are sufficient to cause significant declines in the species. The use of fishing methods that reduce this mortality risk must be a conservation priority in future.
This species has been identified as being of particular risk of collision with offshore wind farms (Bradbury et al. 2014), but impacts appear limited as yet. Impacts from waste, particularly plastic pollution are currently unknown, but have the potential to reduce reproductive success. The species is hunted for food in some places, for example, a small annual harvest is carried out on Sula Sgeir, off north-west Scotland.

Conservation actions

Conservation Actions Underway
The species is listed on the African Eurasian Waterbird Agreement. It is covered by the EU Birds Directive as a regularly occurring migratory species. In Europe it is currently listed within 34 marine Important Bird Areas. Within the EU, it is currently listed within nine Special Protection Areas.

Conservation Actions Proposed
The following information refers to the species's European range only: Identification and protection of important sites at sea. Collection of more information on individual movements to assist careful placement of offshore wind farms. On-board monitoring programmes on fishing vessels to determine the number of birds caught across the region, and implementation of bycatch mitigation measures where appropriate.

Acknowledgements

Text account compilers
Butchart, S., Calvert, R., Bennett, S., Ekstrom, J., Fjagesund, T., Ashpole, J, Martin, R.


Recommended citation
BirdLife International (2022) Species factsheet: Morus bassanus. Downloaded from http://www.birdlife.org on 25/06/2022. Recommended citation for factsheets for more than one species: BirdLife International (2022) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 25/06/2022.