Site icon Conservation news

U.S. whale entanglement figures steady in 2017

  • The National Oceanic and Atmospheric Administration (NOAA) recorded 76 whale entanglements in U.S. waters in 2017.
  • Floating fishing gear and other trash in the sea can impede a whale’s ability to feed and swim.
  • Humpback were most often seen entangled; historically, the species usually accounts for about two-thirds of reports in a given year.
  • Despite North Atlantic right whales only having been involved in two known entanglements in 2017, scientists say that any run-in with gear or trash threatens the recovery of the species, which now numbers around 450 animals.

The number of whales ensnared in fishing nets and other debris in U.S. waters didn’t change much between 2016 and 2017, according to a report by the National Oceanic and Atmospheric Administration (NOAA) released in early December.

Humpback whales (Megaptera novaeangliae) were the species that most often turned up entangled, NOAA experts said in a teleconference on Dec. 6, probably because they swim close to shore where struggling whales can be most easily spotted.

A team works to remove fishing gear from a whale. Image by Michael Dawes via Flickr.

The report, published annually, lays out the numbers of entangled whales in 2017, as well as their species, where they were spotted and what snagged them. The authors also tried to determine the fisheries and parts of the country that were the sources of the gear that ended up entangling whales. More than two-thirds of the 76 documented cases of entanglement in 2017 involved nets, traps and other gear used by commercial or recreational fishermen.

The Northeast and Mid-Atlantic, the West Coast and Alaska saw decreases in entanglements compared to 2016, while reports increased in Hawaii and remained steady in the South Atlantic region.

Scientists figure that when a whale gets tied up in ropes, lines and floating trash, it’s likely to die unless it gets help, said Sarah Wilkin, who coordinates NOAA’s response to strandings and entanglements. Tangling with fishing nets and lines can impede a whale’s ability to move in the water, thwarting its ability to find the tons of food necessary to maintain its bulk.

A humpback whale entangled in a net. Image by Michael Dawes via Flickr (CC BY-NC 2.0).

That’s especially concerning for the North Atlantic right whale (Eubalaena glacialis), an IUCN-listed endangered species. There were only two cases of entanglement for the species in U.S. waters in 2017. But mid-year, NOAA announced a still-active marine mammal “unusual mortality event” for the species, and 17 would die over the course of the year. In Canadian waters, researchers suspect that five died as a result of their injuries from fishing gear in 2017, according to the report.

“Given the endangered status of North Atlantic right whales — recent population estimates indicate only about 450 individuals remain —and declining trend of the species, any entanglement is a major threat to their recovery,” the authors wrote.

The population of right whales off the East Coast of the U.S. appears to have plateaued in recent years, after the species came back from a low point of 270 animals in 1990. The animal’s stagnating recovery, even amid the surge in efforts to rescue entangled whales and avoid their contact with gear in the first place, has perplexed scientists.

A disentanglement training exercise in Hawaii. Image courtesy of Coast Guard News via Flickr (CC BY-NC-ND 2.0).

Recent research suggests that towing around gear could be hampering female right whales’ ability to maintain their weight and carry a fetus to term. More than 80 percent of right whales come in contact with fishing gear at some point in their lives.

The North Atlantic Right Whale Consortium, a group of researchers, conservationists, and representatives of government agencies and industry, reports that there have been no recorded births in 2018 and that the number of right whales could be as few as 411.

Eleven entangled gray whales (Eschrichtius robustus) were spotted in 2017, “much higher” than the average of just over six per year, according to the report.

“The increase in entangled gray whales may suggest the animals overlapped with West Coast fishing efforts more than usual in 2017 during their annual migrations,” the authors write.

Two other species, the minke whale (Balaenoptera acutorostrata) and the humpback, have also been stranding and dying at alarming rates lately.

A  North Atlantic right whale towing a fishing rope. Image courtesy of the Florida Fish and Wildlife Conservation Commission, taken under NOAA research permit #15488 via Flickr (CC BY-NC 2.0).

While it’s difficult to say whether entanglement causes stranding, “There is some overlap in that we get whales that are stranded and entangled,” Wilkin said. But in general, more whales strand than are confirmed to have been entangled in a given year, she added.

NOAA’s Large Whale Entanglement Response Network addressed 50 of the entanglements in 2017, freeing — at least partially — 25 of the whales they went after.

The network comprises a highly trained crew, and while NOAA says it depends on boaters to report sightings of distressed whales, the agency cautions members of the public against trying to help the whales.

“Large whales are the largest animals on Earth, and disentangling them is inherently dangerous,” the report writers said. “Only trained and permitted responders should attempt to disentangle or closely approach an entangled large whale.”

NOAA warns the public not to try to disentangle whales. The agency has regional hotlines to report sightings. Image courtesy of NOAA.

Banner image of a humpback whale by Michael Dawes via Flickr (CC BY-NC 2.0). 

Clarification: This article was amended on Dec. 20 to reflect the ongoing nature of the unusual mortality event that NOAA announced in 2017 for the North Atlantic right whale. The article also misstated the span of time during which 17 right whales died. That period was 2017, not late 2016 through 2017.

Citation

Cooke, J.G. (2018). Eubalaena glacialis. The IUCN Red List of Threatened Species 2018: e.T41712A50380891. Downloaded on 18 December 2018.

FEEDBACK: Use this form to send a message to the author of this post. If you want to post a public comment, you can do that at the bottom of the page.