Justification of Red List Category
Although this species may have a small range, it is not believed to 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.
The population is suspected to be increasing following a reduction in human persecution.
Breeding colonies are found off the coast of south-east Australia, Tasmania and New Zealand. One small colony is also found further north at Norfolk Island (to Australia). Winters in adjacent waters and up the east and west coasts of Australia as far north as the Tropic of Capricorn (del Hoyo et al. 1992).
The Australasian Gannet generally feeds over continental shelves or inshore waters, seldom far from land. Its diet is comprised mainly of pelagic fish, especially pilchard, anchovies and jack mackerel, but also squid and garfish. Prey is caught mainly by plunge-diving, but it is also seen regularly attending trawlers. Breeding is highly seasonal (October to May), nesting on the ground in small but dense colonies. Adults tend to stay within the vicinity of the colony after breeding, with young birds dispersing (del Hoyo et al. 1992).
Bycatch is a concern for all gannet species and Australasian Gannets interact with fisheries throughout the foraging range with considerable potential for impacts from longline and set-net fisheries (Carboneras et al. 2018). However, Australasian Gannets have been assessed as being at relatively low risk from commercial fisheries with an estimated annual mortality of 62 individuals (95% confidence interval 7-222) (Richard and Abraham 2013). The greatest mortality was observed in set-net fisheries (Richard and Abraham 2013).
Text account compilers
Calvert, R., Fjagesund, T., Martin, R., Butchart, S., Miller, E., Ekstrom, J.
BirdLife International (2019) Species factsheet: Morus serrator. Downloaded from http://www.birdlife.org on 17/02/2019. Recommended citation for factsheets for more than one species: BirdLife International (2019) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 17/02/2019.