Researchers record first-ever images and data of a shark experiencing a boat strike
IMAGE:
A 7-METER BASKING SHARK FEEDING NEAR THE SURFACE AFTER IT WAS TAGGED BY RESEARCHERS.
view moreCREDIT: BIG FISH LAB, OREGON STATE UNIVERSITY.
NEWPORT, Ore. – Hours after tagging an endangered basking shark off the coast of Ireland in April, researchers captured what they believe is the first ever video of a shark or any large marine animal being struck by a boat.
The data, collected by an activity measurement device similar to a FitBit and a connected camera, provided scientists a unique opportunity to learn more about the impact of vessel strikes on large marine animals, which is a rising concern around the globe, said Taylor Chapple, a shark researcher at Oregon State University’s Hatfield Marine Science Center and lead author of the study.
“This is the first ever direct observation of a ship strike on any marine megafauna that we’re aware of,” Chapple said. “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.”
Researchers do not know whether the shark, a female about 7 meters long, eventually recovered from the strike. The tag was designed to release itself from the animal at a pre-determined time. About seven hours after the strike, the tag was released and later retrieved by researchers. The data showed the shark never resumed feeding or other normal behavior while it was being monitored, Chapple said.
The findings were just published in the journal Frontiers in Marine Science.
Basking sharks are the second largest known fish, frequently reaching more than 8 meters in length. They are listed as globally endangered by the International Union for Conservation of Nature, and Ireland is one of the only known locations worldwide where basking sharks continue to aggregate in large numbers.
They filter feed at the water’s surface, similar to some whales, which makes them more susceptible to boat strikes. But unlike the whales, basking sharks often sink when killed, making it hard to gauge mortality rates, said Chapple, assistant professor in the Coastal Oregon Marine Experiment Station and Department of Fisheries, Wildlife, and Conservation Sciences in OSU’s College of Agricultural Sciences.
Basking sharks in Ireland were protected under the country’s Wildlife Act in 2022. Earlier this year, the Irish government announced the establishment of the nation’s first National Marine Park, protecting 70,000 acres of land and sea on the coast of County Kerry where basking sharks frequent seasonally for feeding and potentially mating.
Shortly after the park’s establishment, the researchers were conducting a previously planned study in the park boundaries to learn more about basking shark foraging behavior and how such behavior corresponds to environmental factors. As part of their research, they tagged the basking shark with a camera and activity monitor system while it was feeding.
After following the shark at a safe distance for a few hours, the researchers departed the area for the day. The tag was designed to record autonomously until its scheduled release, at which time the researchers located it and recovered the data.
Data from the tag revealed that for several hours following the tagging and tracking, the shark spent most of its time on the surface, continuing its normal feeding behavior, with an occasional dive. Then the shark attempted to make a quick, evasive movement, which was followed by the keel of a boat cutting across its back, just behind its dorsal fin. The shark tumbled through the water and immediately increased the frequency of its tailbeat as it headed to the seafloor.
Video from the camera showed visible damage to the shark’s skin, paint marks and a red abrasion but no apparent bleeding or open wound. Vessel strikes are not always immediately lethal, but even non-lethal injuries can have short- and long-term consequences for the affected animal, the researchers noted.
“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,” said co-author Nicholas Payne, an assistant professor at Trinity College Dublin’s School of Natural Sciences. “Basking sharks filter feed at the surface, like some whales, and this behavior makes them similarly susceptible to strikes.”
The incident highlights the need for additional research on the interactions between water users and basking sharks in the National Marine Park and other hotspots along the Irish coastline, said co-author Alexandra McInturf, a research associate in Chapple’s Big Fish Lab at OSU and co-coordinator of the Irish Basking Shark Group.
“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,” McInturf said. “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.”
Additional coauthors are David Cade and Jeremy Goldbogen of the Hopkins Marine Station at Stanford University; and Nick Massett of the Irish Whale and Dolphin Group in County Kerry, Ireland.
This image depicts the keel of a boat striking a basking shark.
This image shows paint and an abrasion on the back of a basking shark that ha been struck by a boat.
This image shows paint and an abrasion on the back of a basking shark that ha been struck by a boat.
CREDIT
Big Fish Lab, Oregon State University.
Big Fish Lab, Oregon State University.
JOURNAL
Frontiers in Marine Science
METHOD OF RESEARCH
Data/statistical analysis
SUBJECT OF RESEARCH
Animals
ARTICLE TITLE
Behavioral response of megafauna to boat collision measured via animal-borne camera and IMU
ARTICLE PUBLICATION DATE
24-Jul-2024
URI partners on study that tracked whale shark for record-breaking four years
Rio Lady's movements, migration allow researchers to 'investigate whale sharks at a unprecedented degree'
UNIVERSITY OF RHODE ISLAND
KINGSTON, R.I. – July 22, 2024 – A team of researchers at the University of Rhode Island and Nova Southeastern University in Florida have been tracking a 26-foot endangered whale shark – named “Rio Lady” – with a satellite transmitter for more than four years – a record for whale sharks and one of the longest tracking endeavors for any species of shark.
Whale sharks, which live from 80 to 130 years, are the world’s largest fish and third largest creature in the ocean – behind blue and fin whales. The size of a small school bus, they inhabit tropical oceans and swim slowly near the surface, with their mouths wide open, scooping up whatever’s in their path – small fish, fish eggs, and plankton. Annually, they need to travel about 5,000 miles to find enough food to survive. Whale shark populations worldwide have declined, primarily as a result of interactions with humans, to the point where they are now listed on the International Union for Conservation of Nature Red List as Globally Endangered.
Researchers at URI and Nova Southeastern tracked Rio Lady for about 27,000 miles over nearly 1,700 days between 2018 and 2023. Her journey took her through the Gulf of Mexico, the Caribbean and out into the Atlantic Ocean south of Bermuda. A study conducted by the researchers was published in the journal Marine and Freshwater Research, describing movement, migration and habitat use of Rio Lady.
“This was an amazing length of time to be able to track the movements of a wild animal,” said lead author Daniel Daye, who graduated from URI in May 2023 with a master’s degree in biological and environmental sciences. “Four years of data about the movements of even a single individual has allowed us to investigate whale sharks to an unprecedented degree and investigate questions that can’t be answered with shorter tracks.”
Rio Lady was tracked by satellite telemetry using a smart-position and temperature transmitter (SPOT) affixed to her dorsal fin. The tag provided location transmissions over four years of her life. Satellite telemetry has revolutionized the study of animal movement – particularly with marine species – allowing researchers to uncover long-term movement patterns and core areas for marine animals, the study says.
“As the biggest fish in the ocean, it is challenging to follow the movements of whale sharks over long periods of time,” said Brad Wetherbee, assistant professor of biological sciences at URI and an expert on shark movement and migration, who consulted on the project. “But information on the movements of these endangered sharks is important for management of their populations.”
A primary challenge in managing large marine species, such as the whale shark, said Daye, is that they are hard to follow. Whale sharks travel great distances and routinely dive deep, which makes studying the full extent of their habitat difficult.
“Since these sharks travel such great distances, it’s important to identify when and where the sharks are located, along with what they are doing in each of these areas,” said Daye. “This way management can take a more targeted approach so that effort isn’t wasted on areas when sharks are using habitats elsewhere. While Rio Lady is only one shark, the extremely long lifespan of the SPOT tag has allowed us to start examining some of these questions in more detail regarding what sharks do on a year-to-year basis, rather than a single year.”
Rio Lady was first tagged in 2007 with a pop-up satellite archival transmitter affixed to her near the Isla Mujeres, in waters off Cancun, Mexico, that are frequented by hundreds of whale sharks annually from July through August. She was tracked for 150 days before her transmitter popped off. She was re-tagged in August 2018 in the same area by Rafael de la Parra, executive director of Ch’ooj Ajauil AC, an ocean conservation organization in Mexico. De la Parra also collaborated on the study.
During the study, Rio Lady was detected by satellite over 1,687 days – Aug. 30, 2018 to April 12, 2023. For a period of about 1,085 days – Aug. 30, 2018 to Aug. 18, 2021 – 1,354 locations were recorded at relatively frequent intervals. In that time, she traveled about 27,000 miles, covering about 25 miles a day.
Researchers found that Rio Lady occupied three distinct regions in the Gulf of Mexico and timing of when these areas were used was pretty consistent, Daye said. Between July and August, she consistently returned to the waters near Isla Mujeres. In the area known as the Afuera, hundreds of whale sharks aggregate for the largest gathering worldwide – dining on an endless fish egg “buffet,” said Daye.
After leaving the Afuera area, few detections were received during autumn and winter each year of the study. Rio Lady was believed to travel south into the Caribbean Sea, as far as Colombia for two of the years, before returning to the Gulf of Mexico early in the year. Researchers believe Rio Lady’s seasonal migration may be typical for whale sharks that aggregate off the Isla Mujeres in the summer.
“This unprecedented track of Rio Lady sheds new light on long-term consistency of movements and illustrates the type of information that this technology can generate,” said Mahmood Shivji, professor of biological sciences at Nova Southeastern University, who collaborated on the study.
Rio Lady’s continued journey can be followed on the Guy Harvey Research Institute tracking website, click on project 21.
METHOD OF RESEARCH
Observational study
SUBJECT OF RESEARCH
Animals
ARTICLE TITLE
Tracking 4 years in the life of a female whale shark shows consistent migrations in the Gulf of Mexico and Caribbean
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