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Right whales in the Gulf of Maine off Mount Desert Island. ISLANDER FILE PHOTO

Right whale birth rates are troubling



BOSTON, Mass. A study recently published in the journal “Frontiers in Marine Science” says that, despite efforts by fishermen and federal fisheries management authorities, more right whales than ever are getting tangled up in fishing gear. The study also states that injuries and deaths from those incidents “may be overwhelming recovery efforts” for the endangered right whale population.

In the report published in July, lead author Scott Kraus, a whale researcher at the New England Aquarium in Boston, says that while the population of whales has increased from fewer than 300 in 1992 to about 500 in 2015, births of right whales have declined by 40 percent since 2010.

According to the National Marine Fisheries Service, between 2009 and 2013, an average of 4.3 whales a year were killed by “human activities,” virtually all of them involving entanglement with fishing gear.

From 2010 to 2015, 85 percent of right whale deaths resulted from entanglements with fishing gear. Those numbers stand in sharp contrast to what occurred between 1970 and 2009.

According to the report, during those 40 years, scientists attributed 44 percent of right whale deaths to ship strikes and 35 percent to entanglements.

Lethal entanglements aren’t the only problem for the whales. As of last year, 83 percent of all right whales carried scars or were dragging ropes from past entanglements.

According to Kraus and his co-authors, those “sub-lethal entanglements can cause reproductive failure and declining health long after the entanglement is over.”

Based on research over the past two decades, the report raises three significant conclusions. First, until recently, the population was growing at 2 to 3 percent per year, less than half of the growth rate of all other well-studied right whale populations around the world. Second, the population growth rate seems to be dropping, “likely due to a combination of anthropogenic mortalities and reduced calving rates.” Third, deaths and serious injuries from fishing gear entanglements remain far higher than the limits set by the federal Endangered Species Act and the Canadian Species at Risk Act.

As a result, the report concludes, recovery of the endangered whale population is in jeopardy and the whale population is “vulnerable to declines.”

Patrice McCarron, executive director of the Maine Lobstermen’s Association, said this week that it was wrong to blame fishermen for the decline in the number of whale calves born in recent years.

“Given the tremendous positive growth in the right whale population since the 1990s and corresponding changes in how we fish, it is unlikely that fishing gear is the primary cause for a slower rate of right whale reproduction,” McCarron said in an email Tuesday morning. “A more likely explanation is rise in ocean temperatures and changing ocean conditions that have significantly altered when and where right whales frequent their traditional grounds in the Gulf of Maine.”