07-24-2024

Basking sharks are exceptionally vulnerable to ship strikes

Earth.com staff writer

A team of researchers has recently captured unprecedented footage of an endangered basking shark being struck by a boat off the coast of Ireland in April. This incident provided unique data on the impact of ship strikes on large marine animals.

“This is the first ever direct observation of a ship strike on any marine megafauna that we’re aware of,” said study lead author Taylor Chapple, a shark researcher at Oregon State University (OSU)’s Hatfield Marine Science Center.

“The shark was struck while feeding on the surface of the water and it immediately swam to the seafloor into deeper, offshore waters, a stark contrast to its behavior prior to the strike. Our findings demonstrate the risk and impact of vessel strikes and the need for measures to reduce this risk.”

Unfortunately, researchers could not determine if the shark recovered, as the tag released itself seven hours later, showing no resumption of normal activities.

Addressing the issue of ship strikes

The study, published in the journal Frontiers in Marine Science, highlights the importance of addressing vessel strikes, which pose significant risks to marine life.

“Overlap between marine megafauna and maritime activities has long been, and is increasingly, a topic of concern, especially given the increase in maritime traffic and the continued declines of some species. It has been demonstrated that phenomena such as the formation of ‘marine roads’ (i.e., shipping routes) pose significant risk to large surface-active marine megafauna,” wrote the study authors.

Basking sharks’ feeding habits

Basking sharks, the second-largest known fish, are particularly vulnerable due to their surface feeding habits, similar to some whales. These sharks are listed as globally endangered, and Ireland is a crucial aggregation site for them.

In 2022, basking sharks in Ireland gained protection under the country’s Wildlife Act. The establishment of Ireland’s first National Marine Park earlier this year, protecting 70,000 acres of land and sea in County Kerry, aims to safeguard these sharks.

Researchers conducted a study within the park’s boundaries, tagging the basking shark to study its foraging behavior.

Ship strikes have lasting impacts

After tagging, data showed the shark continued normal feeding for several hours, occasionally diving, until it made a quick evasive movement followed by the keel of a boat cutting across its back.

The shark then swam rapidly to the seafloor. Video footage revealed visible damage but no open wounds. Vessel strikes, even if non-lethal, can have lasting impacts on marine animals.

Vulnerability of basking sharks

Nicholas Payne, co-author and assistant professor at Trinity College Dublin, stressed the vulnerability of basking sharks to boats due to their surface feeding behavior.

“The fact that a shark we fitted our ‘Fitbit’ to was struck in this area within a few hours underlines just how vulnerable these animals are to boats and highlights the need for greater education in how to mitigate against such strikes.”

The incident underscores the need for greater education and measures to mitigate such strikes.

Further research is necessary to understand how often basking sharks occupy habitats where they are not visible at the surface.

Protecting an endangered species

Alexandra McInturf, a research associate in Chapple’s Big Fish Lab at OSU and co-coordinator of the Irish Basking Shark Group, emphasized the critical need to study basking shark behavior in Ireland, one of the few places globally where they are still observed regularly.

“This research raises additional questions about whether and how often the sharks are actually occupying such habitats when they are not clearly visible at the surface,” said McInturf.

“Given that Ireland is one of the only locations globally where basking sharks are still observed persistently, addressing such questions will be critical to informing not only our ecological understanding of the basking shark, but also the conservation of this globally endangered species.”

Marine life and human activities

The incident highlights the pressing need for continued efforts to protect marine life from human activities and ensure the survival of endangered species like the basking shark.

The data gathered from this event provide crucial insights into the risks these animals face and underscore the necessity for protective measures to mitigate vessel strikes.

The findings also offer valuable information for future conservation strategies and reinforce the importance of ongoing research to better understand and protect marine megafauna.