Divers off the coast of Nova Scotia have made a rare discovery: a rarely-seen lined seahorse in the seagrass off St. Margaret’s Bay, Nova Scotia.

Divers Nedia Coutinho and Martin Roy, owners of underwater imaging company UW Distribution, discovered the threatened seahorse during a routine dive.

While the lined seahorse’s habitat does technically extend all the way to Nova Scotia, it’s more often spotted among the mangroves, sponges, and floating mosses in the waters of the Caribbean and central America.

In fact, the lined seahorse has not been reported in Nova Scotia waters since 2000. And the last sighting before that was in 1989. Altogether, only about 20 to 25 of the seahorses have ever been recorded off the coast of Nova Scotia.

Coutinho says in her experience diving throughout the Caribbean and on the Great Barrier Reef in Australia, she had never seen a seahorse in the wild before.

“I was obviously not looking for a seahorse, but when I saw it I could not believe my eyes,” she said in a statement.

Lined seahorses, also called hippocampus erectus, are considered a vulnerable species by the International Union for Conservation of Nature and Natural Resources. They are often scooped up as bycatch by shrimp trawlers and other fisheries. They’ve also been threatened by habitat degradation from pollution and coastal development.

Coutinho and Roy snapped a picture of the little creature and sent it along to the University of British Columbia’s Project Seahorse.

Last year, the organization launched a smartphone app called iSeahorse Explore that allows divers and amateur marine lovers to log seahorse sightings and upload photos whenever they find them in the wild.

“This is a thrilling discovery,” Amanda Vincent, director of Project Seahorse, said in a statement.

“These charismatic and mysterious animals are so highly cryptic – and, in many places, so threatened – that we often have to be very lucky to find them.”

Several seahorse species are threatened or endangered due to habitat loss. They’ve also been overfished to be used in aquarium displays, traditional Chinese medicine, or just as curios.

Understanding the scope of the problem in the world’s oceans has been difficult because of the small size of seahorses and their ability to blend into their surroundings. Of the 48 seahorse species listed on the IUCN Red List of Threatened Species, 26 are considered “data deficient” -- meaning there isn’t enough information to know whether they are thriving or disappearing.

Vincent says there are currently fewer than 15 scientists around the world studying seahorses in the wild, which is why getting help from citizen divers like Coutinho and Roy is so important.

Researchers with Project Seahorse are hoping to use the data gathered through iSeahorse to better understand the creatures’ behaviour and the threats they face, as well as to improve seahorse conservation around the globe.