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ISRA FACTSHEETS

AUSTRALIA AND SOUTHEAST INDIAN OCEAN

ISRA FACTSHEETS

AUSTRALIA AND SOUTHEAST INDIAN OCEAN

Hogan-Kent Islands ISRA

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Hogan-Kent Islands ISRA

Hogan-Kent Islands

Summary

Hogan-Kent Islands is located in northeastern Bass Strait in Tasmania, Australia. The area encompasses a central ridge reef feature in between two groups of Islands – the Kent Group and the Hogan Group. The habitat is characterised by reef ridges, scallop beds, rocky reefs, and coarse shelly sand substrates. It is influenced by seasonal well-mixed water, cold fronts, storm surges, and weak winds. This area overlaps with the Beagle Marine Park. Within this area there are: undefined aggregations (Port Jackson Shark Heterodontus portusjacksoni).

Hogan-Kent Islands

Hogan-Kent Islands

DESCRIPTION OF HABITAT

Hogan-Kent Islands is located in northeast Bass Strait in southeast Australia. It is situated in th state of Tasmania, near the border with Victoria. The area encompasses a margin of a central ridge reef feature in between two groups of Islands – the Kent Group and the Hogan Group. The habitat is characterised by shelly substrate from scallop beds, sessile invertebrate habitats, rocky reef, and coarse shelly sand substrate (Barrett et al. 2021; University of Tasmania 2024; NESP 2025).

This area is influenced by well-mixed water in the austral winter and spring (Baines & Fandry 1983; Sandery & Kämpf 2005). There are also influences from cold fronts and storm surges during autumn and winter (McInnes & Hubbert 2003), with weaker wind-driven currents in summer.

This area overlaps with the Beagle Marine Park (Parks Australia 2025).

This Important Shark and Ray Area is benthic and is delineated from inshore and surface waters (0 m) to 65 m based on the bathymetry of the area.

CRITERION C

SUB-CRITERION C5 – UNDEFINED AGGREGATIONS

Kent-Hogan Group is an important area for undefined aggregations of one shark species.

Port Jackson Sharks have been observed resting in aggregations in this area in groups of >1,000 individuals. Aggregations of this size were incidentally observed via autonomous underwater vehicles (AUVs) and remotely operated vehicles (ROVs) deployed to analyse the seabed in both tim periods that this area has been surveyed: July 2018 and August 2024 (Barrett et al. 2021; University of Tasmania 2024; NESP 2025). Animals are observed in association with the reef ridges on the central ridge, and Doughboy Scallop Mimachlamys asperrima beds that characterise this area (Barrett et al. 2021). Although Port Jackson Sharks have been observed aggregating in smaller numbers (~5 individuals) in the broader area (on ledges and in caves), this area has the largest known aggregations of the species in Australia. This aggregation may be for seasonal (winter) feeding purposes due to the nature of observations being recorded adjacent to scallop beds, which Port Jackson Sharks feed upon (Barrett et al. 2021; NESP 2025). This area also coincides with the southern point of their distribution within a large migratory corridor, and as such, the sharks could be using this area to feed and gain energy in preparation for movement out of this area, to locations where they lay their eggs (NESP 2025). As such, the nature of the aggregations may also be for reproductive purposes, with only females being recorded in 2024 (University of Tasmania 2024; NESP 2025). The low sample size is a reflection of the low survey effort of this remote area and further information is required to understand the nature and function of these aggregations.

Hogan-Kent Islands

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