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A diver releases a baby seahorse
Photograph: Tom Burd

The world's biggest ever release of endangered baby seahorses just went down in Sydney Harbour

A record release is good news for Sydney's endangered seahorses

Maya Skidmore
Written by
Maya Skidmore

Sydney, we have good news. Marine scientists just successfully pulled off the world’s largest release of baby seahorses in Sydney Harbour – and yes, this is real life. 

This record drop of 380 endangered White’s Seahorse babies into the waters of Sydney Harbour is legitimately the biggest ever seen in the world, and it’s an extremely exciting development for pretty much everyone involved. 

After being bred in captivity by the Sydney Institute of Marine Science for five months, the little creatures were taken to Chowder Bay, carried down to the sea floor in large plastic bags by divers, and then carefully placed into existing natural seagrasses and ‘seahorse hotels’ that have been built into the environment. The success of these artificial hotels were seen last year when a single endangered seahorse was found living beneath the Opera House

A close up of a baby seahorse face
Photograph: Sydney Institute of Marine Science

After being declared endangered in 2020, and then following the destructive floods of 2022 where the seahorses in Sydney Harbour died in mass numbers, it’s clear that these Sydney natives are in need of serious protection. This latest release isn’t the first time scientists have tried to reestablish the White’s Seahorse population in the Harbour but it is the most successful so far, with scientists saying this seahorse drop had the best survival rate out of any they’ve done. 

When three male seahorses from Chowder Bay gave birth (wild, we know) to hundreds of babies five months ago, researchers were stoked to see a huge amount of them survive. One of the best bits of this whole thing is that despite White’s Seahorses generally only having a survival rate of 1 per cent, 90 per cent of these babies survived the breeding process, a fact that’s keeping everyone’s hopes buoyed for the final goal of Sydney’s seahorses no longer being listed as endangered. 

Seahorse on coral
Photograph: David Harasti

The seahorses will be carefully monitored over the next few months, with the Sydney Marine Institute currently in the process of replanting sea forests, replenishing natural sea grass, and rebuilding seahorse habitats. They’re also planning to do another big release in the near future, with all signs pointing to a happy, healthy and seahorse-full future. 

We love a bit of seahorse hope. 


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