Researchers have carried out a genetic study of Bermuda’s baitfish to help develop a management programme for the several species in island waters.

Baitfish, also known as fry, often school in coastal waters and different species group together in “bait balls”.

But scientists have noticed a decline in some of the species over the past 40 years.

Net fishing for baitfish is banned in several locations, Coot Pond, Whalebone Bay, Shelly Bay and Somerset Long Bay, and researchers have questioned whether protected areas should be more evenly distributed around the island.

As part of a study, recently published in the peer-reviewed scientific journal PeerJ, researchers collected baitfish from ten locations around the island and took DNA samples.

The study found a “high degree” of genetic diversity in and between schools of baitfish, but that interbreeding between Bermudian baitfish and populations in the Caribbean and Western Atlantic was limited.

Joanna Pitt, a marine resources officer for the Department of Environment and Natural Resources, said in the July issue of Currents, the Bermuda Institute of Ocean Sciences newsletter: “As a resource manager, it’s important to be able to balance the ecological sustainability of baitfish populations and their role in commercial and recreational fishing.

“In practical terms, these two pieces of information mean that we need to work to conserve our baitfish stocks, but that we don’t need to worry about the exact placement of protected areas.”

Ms Pitt worked with Gretchen Goodbody-Gringley, a coral reef ecologist at the Bermuda Institute of Ocean Sciences, on the study, with assistance from Emma Strand, a former Bios Research Experience for Undergraduates student and PhD student at the University of Rhode Island.

The team collected samples of baitfish in June and July 2017.

The team has identified the five main species of baitfish in Bermuda: reef silverside, dwarf herring, red ear herring, Spanish sardine and the Bermuda anchovy, but genetic tests have identified a sixth species, the Atlantic thread herring.

Dr Goodbody-Gringley said: “For all six of the species we examined, our results showed a high degree of genetic diversity both within and between baitfish assemblages from different locations around Bermuda.

“This tells us that, in terms of management, we should consider Bermuda’s baitfish species as highly mixed populations in which individuals from all around the island contribute to a single gene pool.”

The tests also found that the endemic Bermuda anchovy was genetically “within 1 per cent similarity” of the bigeye anchovy found internationally.

The results suggested that more research would need to be done to find out if the Bermuda anchovies are endemic.

Baitfish are an important part of the marine ecosystem as they eat plankton and are a food source for bigger fish and birds.

The fish are also often caught with nets to be used as bait or chum.

The annual recorded harvest of baitfishes in Bermuda peaked at 105,072kg in 1988 at the peak of fish trap use and fell to a low of 26,842kg in 1995.