Marine report identifies rare species

Seahorses and fish species including the Ballina angel fish and Elegant wrasse have been found to be rarer than anticipated in a project which has mapped threatened and protected marine species along the coast between Tweed Heads and Port Macquarie.

The Northern Rivers Catchment Management Authority (NRCMA) project was completed by Southern Cross University researchers Associate Professor Stephen Smith, Dr Steven Dalton and Dr Steven Purcell, from the National Marine Science Centre in Coffs Harbour.

The project involved the collection of data on sightings of fish and marine species from recreational divers and research agencies.

"Understanding the geographical ranges and abundance of threatened and protected fishes, and the specific habitats in which they occur, were critical gaps in knowledge,” Associate Professor Smith said.

“We were surprised to find that some species, such as most seahorses, were quite rare in northern NSW waters, except for perhaps deep waters. We also found that the Ballina angel fish and the elegant wrasse were rare. In years past, these species were reported to have been more common at sites from Coffs Harbour to Tweed Heads.

“We cannot really say why so few of these species have been seen recently, and Lord Howe Island and oceanic reefs may be among the last refuges for these species. Although sparse, at least one other species, the Eastern blue devil fish, was sighted commonly by researchers and the diving public.”

In tandem with the study on distributions, a second NRCMA project by the Southern Cross University researchers also measured the specific habitats in which the threatened and protected fish species were sighted on reefs from Julian Rocks to South West Rocks.

“Some of the species were found to be generalists, like the Eastern blue devil fish, which we found in a broader variety of habitats than previously believed,” Dr Purcell said.

“But our measurements also showed that some protected fish species require quite specific habitats. Ornate ghost pipefishes, for example, occurred mostly near large black-coral trees.”

Dr Purcell said those findings reinforced the need for divers to take care when swimming around coral trees and gorgonian corals, which were not very common but could be found around outer islands.

“Our study also urges boat users to use moorings, as these types of underwater structures are easily damaged,” he said. “Trawling can also impact these critical habitat structures in deep waters, highlighting the need for adequate protection to allow sea whips and coral trees to reach a large size, which is needed for some protected fish.”

Dr Purcell said the next phase in their research was to determine habitats used by threatened and vulnerable species at Lord Howe Island, an important site for marine biodiversity in northern NSW.

Photo: The ornate ghost pipefish occur mostly near large black-coral trees.