Created: Sep 29, 2022 07:53 AM
Whale researcher Andrew Stevenson picks up the underwater songs of humpback whales using a handheld hydrophone (Picture from Facebook)
“Groundbreaking” research has shed fresh light on the migrating humpback whales that could help to bring international status to Bermuda’s waters.
Whale researcher Andrew Stevenson, who spent years collecting data for use in the study, is to bring the findings before a major ocean conservation and research conference next month.
“The idea is to get some kind of status for Bermuda’s waters, which would be international recognition,” Mr Stevenson said.
The move would enable groups such as the United Nations International Maritime Organization to direct shipping away from seamounts off Bermuda during times of whale activity.
Mr Stevenson spoke in the wake of this month’s publication by Frontiers in Marine Sciencean open-access science journal, or an in-depth study of detailed whale songs that he recorded off Bermuda.
Instead of relying on a microphone slung over the side of a boat, Mr Stevenson and fellow researchers sent equipment known as Passive Acoustic Monitoring devices to the ocean floor in 2018 and 2019.
The listening devices were sent down to locations Mr Stevenson has come to know from painstaking years of research — including listening to whales from his boat since 2007.
Four torpedo-like machines were submerged on the southwest corner of the Bermuda Platform as well as the Challenger Bank and an offshore point known as Sally Tucker’s.
The devices gathered 12 months of recorded humpback whale song.
After getting the data back to the surface, Mr Stevenson got the recordings for researchers to analysis.
He said the study was comparable to the landmark work undertaken by Bermudian Frank Watlington, who was the first to record humpback whales in the 1950s.
During the Cold War, Mr Watlington was working with the US Navy to eavesdrop on Soviet submarines off Bermuda, when he picked up the songs of humpbacks.
The island’s last in-depth study of whale song was in 1976.
Mr Stevenson said: “This is the first time we have this level of quality songs recorded over a lengthy period.”
Andrew Stevenson retrieves an acoustic recorder from its lengthy deployment from Challenger Bank in 2019, about 15 miles off Bermuda (Picture from Facebook)
Tracking the whales meant uncovering more about their migrations across vast areas of the Atlantic, stopping by Bermuda in their travels from the northeastern corner of the Atlantic by Russia, down to the eastern Caribbean.
Another population frequently visited the northwestern Atlantic.
Mr Stevenson said: “What we’re looking at now is analyzing the song structure between the east and west Atlantic whales — that’s what we are about to embark upon.”
He admitted the work had been “a long slog”, including acquiring the monitoring devices from Jasco Applied Sciences in Canada and bringing them safely back to the surface with their recordings completed.
The dissertation that came out of the research was co-authored by Mr Stevenson with Tamara Narganes Homfeldt, of the Max Planck Institute of Animal Behavior in Germany, as well as the School of Geosciences at the University of Edinburgh; Denise Risch, from the Scottish Association for Marine Science; and Lea-Anne Henry, of Whales Bermuda.
Two other dissertations look at estimates of whale abundance in Bermuda waters, where numbers are thought to run from 700 to 1,500 per season.
Atlantic oasis: a pod of humpback whales surface off Bermuda in this photograph taken by veteran marine life lensman Andrew Stephenson and featured in his book The Secret Lives of the Humpbacks (Photograph supplied)
“I think that’s a good estimate,” Mr Stevenson said.
“We know from acoustic data and visual data that Bermuda is a very, very important stopover. We also know from the abundance estimates that there is a gradual increase in their population — which is great.”
A third scientific paper, which Mr Stevenson plans to present next month in Brazil, focuses on the human impact on whales.
The veteran researcher heads from October 10 to 14 for the general assembly of iAtlantic, an international research group studying areas of conservation significance across the Atlantic Ocean.
Part of the address will concern the human impact, from injury by sea vessels and acoustic interference.
Bermuda’s offshore exclusive economic zone is designated a marine mammal sanctuary, but Mr Stevenson said there was little legislation to back up protection.
He highlighted proposed new marine spatial plans for the island’s waters that would likely increase human activity on the water.
The island hosts busy shipping, while some recreational boats have harassed the seasonally visiting whales by following them too closely.
Mr Stevenson said he would advocate for better protection.
“One of the problems we have here is there’s no real recourse,” he added.
“There’s a $10,000 fine for disturbing whales, and there are guidelines for whale watching — but they’re just guidelines.”