Lifeboats for hammerheads: essential habitats for conservation

The primary objective of this project is to identify essential habitats that are critical for feeding, shelter and reproduction in three threatened hammerhead species – scalloped hammerhead, great hammerhead and winghead – and thus for their global conservation.

Hammerhead species have experienced dramatic population declines due to human activity. So although the hammerhead shark family is the youngest in evolutionary terms, it may become the first to disappear from our oceans. Globally, hammerhead conservation is hampered by our lack of information about the species’ basic ecology, especially habitat use across life stages. We urgently need to understand the specific attributes of the different habitats that juvenile, sub-adult and adult hammerheads rely on for survival.

Hammerheads are highly charismatic and their distinctive appearance sparks fascination in children and adults alike. Unfortunately, seven out of the nine recognised species are threatened with extinction due to habitat destruction and overfishing. Some have experienced population declines of up to 98% in certain regions, highlighting the urgent need for better conservation. However, improved conservation of hammerheads depends on understanding their basic ecology and the physical characteristics of habitats essential for growth, feeding, shelter and reproduction. Due to depleted populations globally and resulting low sample sizes, this information is missing in many species, including the great hammerhead, scalloped hammerhead and winghead – three predators that play key ecological roles in inshore ecosystems. The information available suggests all three species depend on a variety of inshore habitats that are subjected to human alteration like coastal development, pollution and fishing. Currently, we do not know which combination of habitats represent areas necessary for the survival of juveniles, sub-adults and adults. Thus, we must determine the different habitat types needed to maintain populations. Unfortunately, we also must accept that we live in a world where it is unlikely that the main threats to many shark species, including hammerheads, can be fully removed. Thus, it is incredibly important to find critical priority areas for conservation. Without determining the habitat types hammerheads rely on for feeding, shelter and reproduction as well as the physical characteristics of these habitats, this will be difficult to do. Thus, we will use a multi-method approach across northern Australia to outline criteria of critical hammerhead habitats for great hammerheads, scalloped hammerheads and wingheads and identify such areas across their global distribution. Identifying and protecting important hammerhead habitats globally will be a key step in population recovery and ensure that they will continue to call our oceans their home.

Our main goal in this project is to determine the characteristics of habitats needed for feeding, reproduction and shelter by great hammerheads, scalloped hammerheads and wingheads across northern Australia and identify similar habitats across their global distribution. By combining acoustic/satellite telemetry, diet studies, remote sensing and environmental loggers, as well as catch and drone surveys, we aim to:

• Identify pupping grounds and potential nurseries as well as study habitat use by juveniles in nurseries.
• Investigate the environmental and physical characteristics of different habitat types used by juvenile, sub-adult and adult hammerheads over time.
• Study the feeding ecology of the three species to identify critical foraging habitats.
• Build species distribution models based on our data from northern Australia to identify further important hammerhead habitats for global conservation.
• Conduct risk assessments across identified important hammerhead habitats with regard to climate change, coastal development, fishing, etc.