Whale Strandings Largely Caused By Vessel Strikes, New Study Indicates

LONG ISLAND, NY — A new analysis of whale strandings has revealed that vessel strikes are a major driver in the incidents.

A paper written by Stony Brook University's School of Marine and Atmospheric Sciences professor Lesley Thorne and published in Conservation Biology spotlighted an analysis of East Coast data from 1995 to 2012 on the location, date and timing of strandings. The data revealed that vessel strikes, exacerbated by increased vessel traffic in whale foraging areas used by juvenile humpback whales — is a major contributor to strandings.

On Long Island, deceased humpback whales have been found more often in recent years: A deceased humpback whale was found in Westhampton in 2019, likely due to a vessel strike, officials said. In 2020, a deceased humpback whale was found floating about six miles off the coast of Montauk, the Atlantic Marine Conservation Society said.

According to the paper published in Conservation Biology, by the early 1900s, populations of many large whales were devastated by commercial whaling.

"Today, large whales are still affected by multiple stressors caused by humans. These include pollution, entanglement in fishing gear, disturbances such loud noises in the water, vessel strikes and other activities generated by people. These activities can lead to injuries anddeaths as illustrated by strandings of whales," the paper said.

Led by Lesley Thorne, PhD, the study investigated whale strandings and used data collected by the U.S. Marine Mammal Health and Stranding Response Program, along with information collected on mortality and serious injury determinations for humpback whales on the East Coast.

More than 200 strandings of humpback whales occurred from 2016 though 2022, and around 500 strandings occurred in total going back to 1995, the data indicated.

Thorne and co-author Dave Wiley, PhD, assessed spatial and temporal patterns of strandings relative to patterns of potential threats to large whales such as vessel traffic, entanglement in fishing gear, and offshore wind development. While they looked at strandings of all large whales, the detailed analysis focused on humpbacks since these whales dominate the strandings data, experts said..

Contrary to "unsubstantiated claims", the authors found no evidence that offshore wind development along the Northeast coast played a role in any observed patterns of strandings and on MSI determinations in humpback whales, they said.

"Very little offshore wind energy development occurred over the study period, yet we examined potential threats from offshore wind in different phases of development," Thorne said. "We focused more on offshore wind site assessment and characterization to match the phase that predominantly occurred during the period. And our spatiotemporal assessment did notsuggest a link between strandings and site assessment and characterization surveys for offshore wind farms."

The researchers reported that the New York and Virginia coastlines are "hot spots of whale strandings."

The data revealed high vessel traffic in those regions, which increased markedly during the period of unusual whale deaths and strandings.

Humpback whales began regularly using the summer foraging habitat in New York waters around 2011, Thorne said. Humpback whales feeding in New York and Virginia are predominantly juvenile whales, which feed in nearshore waters in those states. The researchers noted that increased vessel traffic in those regions, combined with foraging activities, and the inexperience of juvenile humpbacks, created a setting that made the whales more vulnerable to vessels striking and injuring them, they said.

The authors also wrote that "in addition to increases in vessel traffic, changes to humpback whale habitat use may play a role in the observed increases in stranding and mortality and serious injuries."

Although increased vessel traffic causing whale strikes appears to be a driver of continual whale standings on the East Coast, Thorne and Wiley said that their paper outlined important gaps in knowledge that needed to be addressed to better understand the causes of whale standings.

They outlined three key steps for future research: "First, a more thorough understanding of the movements and habitat use of humpback and other large whales, both spatially and seasonally, is needed to better understand and predict threats to these species. Second, assessments of broad spatiotemporal changes to the abundance and distribution of prey species that might influence large whale distribution are needed to understand both the habitat use and health of large whales. Third, more work is needed to determine how habitat use and foraging behavior (e.g., surface feeding and feeding in shallow coastal habitats) might affect risk of vessel strike."