Researchers discover millions of sharks have fishhooks stuck in their bodies from commercial fishing lines that can stay lodged up to SEVEN years
- Researchers tacked tiger sharks in Tahiti between 2011 and 2019
- They found that 38 per cent of the sharks was stuck with a hook at least once
- Hooks can stay in their body for years and cause necrosis or internal bleeding
Millions of sharks around the world are silently suffering the effects of commercial fishhooks embedded in their skin without any means of getting them out on their own.
According to new research from the Hawai’i Institute of Marine Biology at the University of Hawai’i Mānoa, fishhooks embedded in a shark’s skin or mouth can remain for several years and lead to major health problems, including internal bleeding and necrosis.
Between 2011 and 2019, the research team tracked tiger sharks in the ocean waters surrounding Tahiti, and found that 38 per cent were hooked at least once by a fishhook or similar industrial fishing gear during that period.
Scroll down for video
Researchers from the Hawai’i Institute of Marine Biology at the University of Hawai’i Mānoa tracked tiger sharks in the waters around Tahiti for eight years and found 38 per cent ended up with at least one commercial fishhook in their body during that period
‘This is a problem that likely affects millions of individual sharks across the world’s ocean,’ Carl Meyer, an associate researcher at the Hawaii Institute of Marine Biology, told Newsweek.
‘Sharks are hooked in a broad variety of fisheries ranging from coastal recreational angling to commercial open-ocean longlining.’
Longlining involves using a single fishing wire that can have between several dozen and several thousand hooks on it.
These longlines are cast out into the ocean and either left on the sea floor or on the ocean surface using floats, where they typically remain for several hours before being hauled back in.
Commercial fishers who use this technique mainly target high-value tunas and swordfish, according to Meyer, but numerous other ‘bycatch’ species can end up on their hooks.
Researchers believe the leading cause of hooking is commercial longlining, which can have between several dozen and several thousand hooks on a single line
Some hooked sharks will bite their way off lines, which can leave long strands of fish twine dragging behind them, something that can impede their ability to swim or get wrapped around a fin and cause necrosis
‘”In most cases, the fishers do not want to catch sharks—the sharks are simply attracted to the same bait as target species, or to the hooked target species themselves,’ Meyer says.
‘If hooked, sharks often break or bite the line, or are cut loose by fishers without them removing the hook.’
‘After these interactions, sharks may swim away with hooks embedded in their stomachs, throats, mouths or externally around the jaws—or elsewhere on the body—and may also be trailing line from those hooks.’
The hooks can cause anything from minor irritation to internal bleeding as a swallowed hook tears at the shark’s internal organs.
Researchers observed hooks that had been embedded for up to seven years
One immediate change that could help minimize the damage done to sharks is shifting from stainless steel hooks to carbon steel hooks, the more pliable nature of which would help them to fall out naturally much sooner
Hooks can also interfere with shark feeding, and fishing lines trailing from hooks can wrap around fins and cut off circulation to the fins themselves, causing necrosis.
One immediate change Meyer recommends is shifting from stainless steel hooks to carbon steel hooks, the latter of which would likely fall out much sooner.
‘Switching to the use of non-stainless hooks is not a panacea but will help to reduce impact by decreasing the time required for sharks and other animals to shed embedded hooks,’ Meyer says.
What is longline fishing?
Longline fishing is a technique that uses a mainline that has a number of baited hooks attached to it.
In areas such as the North Pacific, commercial fishing boats can have as many as 2,500 baited hooks at any one time.
The technique can be used to catch fish such as tuna, cod and swordfish.
Longline fishing often catches species other than those intended, including sharks, turtles and dolphins.
Some estimates suggest that up to 40 per cent of caught sea life is bycatch, much of which is then thrown back overboard as it is not wanted.
Wildlife charities have urged fisheries to utilise new technologies to reduce the amount of bycatch to protect our oceans.