NOAA, Canadian Fisheries pursue cause of right whale deaths

ELLSWORTH — Responding to the deaths of more than a dozen animals in the past three months, NOAA Fisheries last week declared an “Unusual Mortality Event” for endangered North Atlantic right whales throughout their range along the Atlantic coast, primarily in the Gulf of St. Lawrence region of Canada.

The event began in June, and the number of strandings remains high, with the most recent stranding occurring offshore of Cape Cod on Aug. 14, 2017.

As part of the investigation, NOAA Fisheries is assembling a team of independent scientists to coordinate with the agency’s Working Group for Marine Mammal Unusual Mortality Events and the Department of Fisheries Oceans Canada (DFO) to review the data collected and to determine potential next steps.

Since June 7, ten right whale deaths have been recorded in Canada — primarily in the Gulf of St. Lawrence — and two in U.S. waters. A third North Atlantic right whale mortality occurred in U.S. waters in April, before the designated Unusual Mortality Event is deemed to have begun.

The 13 recorded whale deaths far exceeds the number anticipated by scientists. According to NOAA Fisheries, the combined annual average number of dead whale strandings in the United States and Canada is 3.8.

As of Monday, full necropsy examinations had been conducted on seven of the 12 dead whales but results are not yet available. Two whale carcasses could not be retrieved.

Several, if not all, of the dead whales showed evidence of injury from ship strikes, entanglement with fishing gear or both. DFO has imposed speed restrictions on vessels traveling in the western Gulf of St. Lawrence and closed or modified several fisheries in the area to reduce the risk of entanglements.

In the United States, ship speed reduction rules are in effect when large numbers of right whales are present. Vessels at least 65 feet long are required to travel at 10 knots or less while entering or departing ports. This rule was put into place primarily for right whale presence in New England and Mid-Atlantic waters from November through July.

Recreational boaters must stay at least 100 feet away from whales at all times.

Prior to this year, four Unusual Mortality Events involving large whales have occurred in the Atlantic basin — in 2003, 2005, 2006 and 2016-2017. Three of those events primarily involved humpback whales: 16 in 2003; 48 in 2006; and 51 in the ongoing 2016-2017 investigation.

The 2005 event involved 34 whales of multiple species. Causes of the three closed Unusual Mortality Events were undetermined. The current 2016-2017 event is still under investigation.

One previous Unusual Mortality Event involving North Atlantic right whales occurred in 1996. This event involved six whales that stranded dead in Florida and Georgia over a two-month time period (January and February). One of these animals died as the result of ship strike but the cause of death was uncertain in the remaining five.

Scientists are seriously concerned about the high level of right whale mortalities this year.

According to NOAA Fisheries, in 2011, the western North Atlantic right whale population numbered at least 465 individual animals. Over the past six years, analysis of sightings data suggests a slight growth in population size, to perhaps 500 right whales.

Despite that, North Atlantic right whales remain critically endangered and with such a small population, the population trend could change quickly.

Stephen Rappaport

Stephen Rappaport

Waterfront Editor at The Ellsworth American
Stephen Rappaport has lived in Maine for nearly 30 years. A lifelong sailor, he spends as much time as possible messing about in boats. [email protected]

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