Tagged shortfin mako shark caught and killed by fishermen

Tagged shortfin mako shark has ocean journey cut short
Mako shark. Credit: Guy Harvey Ocean Foundation

For one week every year people seem glued to their televisions watching program after program about sharks. After that week, the spotlight on sharks seems to fade – but not for the researchers who are studying these apex predators all 52 weeks of the year.

One thing they've learned in the decades of study – sharks have way more to fear from humans than the other way around. For evidence of such, look no further than research being done at Nova Southeastern University's (NSU) Guy Harvey Research Institute.

Earlier this year a team of researchers were off the coast of Ocean City, Maryland catching, tagging and releasing shortfin mako sharks. They have been doing this for more than a decade as a way to gather information about these animals so they can be better protected.

Unfortunately one of the sharks tagged during that excursion has been caught by fisherman off the coast of Rhode Island. The shark, named SeaWorld 5 (after the organization that sponsored the satellite tags), was tagged on May 25, 2018.

"We've had our satellite tagged sharks captured often during the study, and it's always sad when this happens because it not only interrupts the shark's migration but also hinders collection of data aimed at creating a sustainable fishery," said Mahmood Shivji, Ph.D., the director of NSU's GHRI. "At the same time we also understand that most of the tagged makos that have been captured have been taken in legal fisheries. But it does illustrate the gauntlet of hooks these sharks have to navigate on their migrations."

Tagged shortfin mako shark has ocean journey cut short
Tagged shortfin mako shark. Credit: George Schellenger

Turns out SeaWorld 5 lasted just 37 days after being tagged, logging 1,565 miles. The shark was captured by the longline fishing vessel 'Eagle Eye' and the tag was turned over by Captain John Caldwell after seeing a story in the local media about the missing tag. According to Caldwell, the shark was harvested in compliance with all rules and regulations.

"We appreciate Captain Caldwell getting in touch with us so he could return the satellite tag," said Brad Wetherbee, Ph.D. "The tags are a significant cost to our research, so we work with all fishing boat captains so they understand what's at stake and what to do if they catch one of our tagged makos. It's never a wrong time to do the right thing."

NSU's GHRI has tagged almost 100 mako sharks, with more than 30% having been caught and killed. This rate of fishing mortality is 10 times higher than previously thought and has helped convince fishery managers to increase protections for this economically and ecologically important species. Many of these sharks can be followed online in near real-time at www.nova.edu/sharktracking

"The satellite tags, which are affixed to a shark's dorsal fin, report the shark's location every time it breaks the surface of the water and are used to better understand the migration patterns of these open ocean travelers," said Greg Jacoski, executive director of the Guy Harvey Ocean Foundation. "Recovering the tag back allows researchers to refurbish and deploy it on another shark, helping reduce costs."

This shark is one of a handful that were sponsored by SeaWorld Parks & Entertainment (SEA) as part of a partnership with world-renowned marine artist and scientist, Dr. Guy Harvey. The partnership, announced in 2016, focuses on ocean health and the plight of sharks in the wild. The two organizations partnered to raise awareness of these important issues and to collaborate on science and research to increase understanding of how to better protect these critical predators and their habitats.

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Citation: Tagged shortfin mako shark caught and killed by fishermen (2018, August 1) retrieved 19 January 2021 from https://phys.org/news/2018-08-tagged-shortfin-mako-shark-caught.html
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