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Gareth Jordaan at his graduation ceremony held at the UKZN Westville campus last week. Picture: Abhi Indrarajan
The instances in which sharks are caught and sometimes killed as bycatch by commercial fishing vessels are often not recorded properly – leading to inaccurate shark population assessments. Photo by Jakob Owens on Unsplash
These concerns formed the backbone of Gareth Jordaan’s research, which earned him a Master of Science degree in Biology from the University of KwaZulu-Natal (UKZN) last week.
Jordaan, a passionate environmentalist who was a research assistant based at the Oceanographic Research Institute (ORI) in Durban, said the university in a statement, accumulated a unique dataset of information on sharks during his four month-long investigations at sea.
He was particularly interested in shark bycatch and discarding practices by pelagic longline fishing fleets.
“Global shark landings have increased over the last few decades, with many being caught as bycatch from fisheries targeting tuna and swordfish.
Some of the captured sharks are retained and prepared for export, whereas others are discarded overboard. The species, numbers and fate (alive, injured, or dead) of discarded sharks are not recorded.
This omission gives rise to hidden shark mortalities and ultimately inaccurate shark population assessments.”
He explained that sharks were apex predators which played a vital role in balancing the marine ecosystem and several species were listed as being vulnerable or threatened on the International Union for Conservation of Nature (IUCN) red list.
As part of his research, Jordaan was provided with landings data – collected when fishing vessels off-loaded their catch in port – from the Department of Agriculture, Forestry and Fisheries (DAFF).
“He also went out to sea on eight pelagic longline fishing vessel trips to get information on species composition of catches, discard practices and the fate of the discarded sharks.”
Jordaan’s study, said the university, was the first to investigate shark discards in pelagic longline fisheries in the south-east Atlantic Ocean and south-west Indian Ocean regions, and provided evidence that shark landings records grossly underestimated shark mortalities as a result of fishing.
“Jordaan’s research is significant in estimating the number of sharks discarded (alive and dead) by pelagic longline vessels, and it provides important information to fisheries managers on the total shark mortalities that occur at sea, that may not be accounted for in the landings numbers.”
This, the university explained, ultimately led to more accurate population assessments of those shark species where discards were significant and for those that were more vulnerable than others to over fishing.
Jordaan said foreign longliners fished seasonally along the east coast where they caught mostly tuna and sharks.
Local longliners fished year-round, mainly along the west, south-west and south coasts and caught the bulk of sharks.
Mainly blue sharks and shortfin makos were caught.
“Blue shark mortality is much higher than reflected in DAFF landings data,” said Jordaan.
Jordaan said he had always had an interest in sharks since his time in high school where he started scuba diving with them.
Through his research he hopes to find a way to curb the shark bycatch problem in longline fishing vessels.
A keen sportsman, scuba diver and lover of the outdoors who is passionate about living sustainably, he plans to develop his skills in fisheries assessments going forward in order to make sure fisheries were operating sustainably.
“I also want to make people aware of the importance of sharks and help them to realise that sharks are not the enemy. I want to help sustain these incredible, vulnerable animals.”