Predatory fish once common in our waters including groupers and snappers are at “critically low numbers”, causing a threat to Bermuda’s coral reefs, according to a new report.

Scientists Thaddeus and Jessie Murdoch released the report through the Bermuda Reef Ecosystem Assessment and Mapping (Bream) Programme.

The report — Baseline Condition of the Coral Reefs and Fishes Across Three Depth Zones of the Forereef of Bermuda — also revealed that hard corals are in “good to very good” levels across most of the deep reefs and protected parrotfish appear to have recovered from the overfishing in the 1980s.

Bermuda also enjoys high numbers of plant-eating fish across the lagoon, forereef and rim, which contribute to healthy reefs by preventing marine plants from overgrowing hard corals.

The report covers information collected from 2004 to 2011 by the Murdochs and their team of local and international scientists and graduate students. During that time, the Bream crew measured the amount of corals, marine plants, plant-eating fish and predatory fish at more than 180 reefs located across all of Bermuda’s reef habitats.

Thaddeus Murdoch believes that the loss of predatory fish is cause for alarm.

“Large predators like black grouper carry out important work by managing the numbers of small and large parrotfish that live on the reef,” Dr Murdoch said.

“Smaller predatory fish such as red hind, cony and grey snappers are also needed, as they keep coral-killing damselfish from spreading across lagoonal patch reefs.

“Bermuda’s coral reefs protect the island, give us food, and provide exciting experiences for locals and tourists alike. However, our reefs, along with those across the world, face destruction from an increasingly acidic ocean and increasingly violent storms.

“Our reefs can face these serious threats, but only when predatory fish like grouper and snapper, as well as plant-eating fish like parrotfish and surgeonfish, are abundant, marine seaweeds are sparse, and hard corals are healthy.

“Commercial and recreational fishing annually constitute only a very small portion of economic value generated by the services provided by Bermuda’s coral reefs to our society. However, we oversee the condition of our reefs as if they are primarily a fisheries concern.

“Reef condition is really a tourism and coastal protection issue, and should be managed accordingly,” Dr Murdoch continued.

According to Dr Murdoch, Bermuda can restore predatory fish populations by restricting the rate at which commercial and recreational fishers catch groupers and snappers, limiting the sale of key predatory fishes during their spawning season, expanding the seasonal prohibition and extent of protected spawning areas where necessary, and enhancing marine resource enforcement.

“Our centuries-old Bermuda reef fishery, and the multigenerational livelihoods that it provides, can only persist if we maintain the numbers of our breeding groupers and snappers. Marine-protected areas are one way to invest in our reefs, and they provide a valuable return in the form of a constant supply of fish that leave the protected areas and which we can eat.”

Dr Murdoch pointed out that if we ignore the loss of predatory fish on our reefs, it is likely that our coral reefs will erode.

“In an era of rising sea level, loss of reef structure will allow higher levels of storm waves to damage and remove our coastal properties and beaches, while also reducing the visual appeal of Bermuda’s waters to both visitors and locals,” he said.

The forereef of Bermuda surrounds both the island and its lagoon and encompasses an area of about 400 square kilometres. The coral-rich forereef protects Bermuda from storms, enhances tourism experiences, generates sand for our beaches, and provides habitats for the fishes we like to eat.

A spokesman for Bream said: “The Bream report provides clear evidence that the cover of corals remains high at forereef locations, but is lower at deeper depths within the lagoon and particularly at nearshore reefs where marine plants are overly abundant and plant-eating fishes are scarce.

“Predatory and plant-eating fishes are critical to maintaining healthy reefs.”

• The report is available at www.bermudabream.org