How seahorse hotels protect endangered species in Australia

While I love all animals, as a marine ecologist, I’m particularly drawn to the seahorse. But the threat of extinction is genuine for all these species. And I continually ask these sorts of questions:

• How do we manage the environment for threatened species?
• When considering the White’s seahorse, what’s the impact on development?
• How are seahorse hotels helping animals and projects move forward?

Since the endangered listing for the White’s seahorse, every development or activity proposed along the coastline where they live now requires a set of approvals. We must consider the impact and have a management plan. 

How do we manage the environment for threatened species?

Australian laws protect important plants, animals, ecological communities, and heritage places. They are called Matters of National Environmental Significance (MNES). Anything that could affect an MNES, such as commercial harvesting or urban development, requires government approval.

When development is proposed, our team is called in. Once we’re in the field, we must determine whether any threatened plants or animals are potentially living in a project area. Then, we need to understand if any human activities will:

1. Harm, disrupt or lead to a long-term decrease in its population or territory.
2. Decrease the availability or quality of their environment to the point that they are likely to decline. Or will it negatively affect the habitat critical to their survival.
3. Disrupt breeding or introduce disease or an alien species harmful to them.

If the assessment finds the project will negatively affect a threatened plant or animal, further analysis is required. The goal is to reduce or remove the impact.

White’s seahorse: The impact on development

Seahorses are a unique and fascinating fish. They belong to the Syngnathidae family and enjoy natural habitats such as sponge gardens, seagrass meadows, and soft corals. They also make their homes near artificial habitats, including jetty pylons and swimming enclosure nets.

The White’s seahorse (Hippocampus whitei) is widespread along the east coast of Australia. They live in shallow estuaries and coastal inlets from Hervey Bay, Queensland, in the north to Sussex Inlet, New South Wales, in the south. In July 2019, the government listed the White’s seahorse as an endangered species in Australia—the first Syngnathid to appear on the list. Their decline is mainly associated with losing natural habitats due to human activity..

White’s seahorse is now an MNES. Any activity where they’re likely to live must now consider its impact on them. The implications are far-reaching and potentially affect projects associated with every sponge garden, seagrass bed, pier, or swimming net along about 1,400 kilometres of coastline. So, if you have a development proposed in this area, part of your approval process must now include management of the White’s seahorse.

Interestingly, the White’s seahorse likes to make their home on artificial structures such as swimming nets and piers. This preference for artificial structures makes it more likely that they’ll be present in areas where projects will take place.

While the seahorse may be anywhere along the New South Wales coast, project managers must test this assumption on a project-by-project basis. To determine their presence, we’ve found combining trained scientific divers and eDNA a more effective way than using drop cameras and remotely operated vehicles. However, these methods are costly and time-consuming. And it may not prove or disprove their presence. Therefore, we find it best to apply the precautionary principle for these rare, enigmatic animals—assume they are present and manage them suitably. Even if we don’t find evidence of the seahorse in a project area, we recommend proper management regardless due to its cryptic, mysterious nature. 

Seahorse hotels: How they help animals and projects move forward

Since the threatened species listing, the management of White’s seahorse has been supercharged with a boom in research and conservation efforts.

When a project will impact the seahorse, it must have a management plan. The plans can vary. However, they contain actions to minimize impacts, which include alternative construction methods and project timing. It’s vital to consider typical seahorse life cycles when working on projects. We must slow down high-risk activities around sensitive breeding periods. The plans recommend that scientific divers relocate any seahorse away from harm before any work occurs.

But what happens if there are no suitable nearby new homes? That’s when we become hoteliers.

We’ll build and install seahorse hotels as temporary homes.

The hotels are made from biodegradable metal and look like discarded crab traps, which are popular with seahorses, who often use the traps to create their home. We install these hotels about three months before the seahorses arrive. Once in the water, the hotels gather algae, sponges, and other marine growth, which makes them more attractive to their new residents. These hotels provide temporary accommodation for the seahorse while any potentially harmful activity occurs.

Seahorse hotels are proving successful in our management plans and relocations in Sydney Harbour, including at Parsley Bay, Manly Wharf, Clontarf, and Kamay in Botany Bay. Two projects this year have been typical in their type and management process. In Clontarf, the tidal swimming net enclosure was replaced with a larger net. The old net was being demolished, but swimming nets are known critical habitats for seahorses. For Kamay, a new marine infrastructure project required a jetty installation over a highly productive seagrass bed. Seagrass beds are known natural high-value habitat for White’s seahorse. Both projects took two to three days of diving, where we found up to a dozen seahorses and relocated them approximately 100 to 500 metres away to preinstalled seahorse hotels.

The hotels can provide a high-quality, potentially permanent habitat for the seahorse. They are removed from development areas and can explore their surroundings. Over time, they may return to their natural environment—or simply make the hotel their home. 

Do I need to consider seahorse hotels for my development?

If you’re considering a project along the 1,400-kilometre coastline from Queensland to New South Wales the answer is simple: yes. Your approvals process must consider White's seahorse, and a management plan will be part of your application.

The recent management of the White’s seahorse is a success story. It’s a concrete example of how industry and institutions can use an endangered listing and the legislation protecting it for positive conservation outcomes. We’re seeing concepts such as "endangered" and "MNES" taken from paper and turned into real-life actions. They are helping species that need our help to survive and thrive.

Working with our clients, we’ve helped relocate over 50 seahorses, protecting them from harm’s way. As we look into the future, we anticipate our efforts contributing to delisting this fascinating species.