Philip Matich, a marine biologist at Texas A&M-Galveston, took part in an international study that showed shark populations have seen a sharp decline over the past 70 years.
According to the study, the decline is due to overfishing and loss of habitat, causing many shark species to become threatened or endangered. The research was published in the latest issue of Nature, a weekly international journal.
During the study, Matich and his team of researchers sent out more than 15,000 baited remote underwater video stations on 371 coral reefs in 58 countries. No sharks were found on 20% of the surveyed reefs.
These findings supported a belief that the demand for shark products such as fins and meat, as well as bycatch — sharks found in nets of fishermen seeking other fish — are key contributors to the overall decline in shark populations.
“The study globally assessed sharks at coral reefs, which included 59 different species in the Atlantic, Pacific and Indian Oceans,” Matich said in a release. “These ranged from Caribbean reef sharks and bull sharks to hammerheads, tiger sharks and many other species, including those not tied to coral reefs.
“But sharks were completely or nearly absent from some countries, which was not expected considering the importance sharks play in maintaining the stability of marine food webs. Many of the nations that lacked sharks were characterized by low socioeconomic status, which can affect conservation and management due to available resources, including finances, personnel, food security, education and infrastructure.”
Matich said in the release that this study shows if corrective measures are not taken in areas with ineffective management, then shark populations will continue to dwindle. Matich added that shark populations are important to determine overall ocean health.
“Sharks have important roles in marine ecosystems, but disturbance can alter this role,” Matich said. “A major disturbance to sharks and their ecological roles is habitat deterioration — as habitats are damaged, the resources they provide, like food and shelter, can change, often negatively. In turn, changes in shark populations can further affect the health of ecosystems because they help regulate prey populations by eating and scaring them, affecting behavior and abundance when present.”
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