The debate about grey nurse shark numbers has been a passionate one ever since I arrived here 10 years ago, but the only way we are going to know is to do more counting and genetic testing of the sharks in the water. Whether there are 1,000 or 8,000 sharks, we don’t know.
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Generally the sharks are here for six months and head north when water temperatures drop, but the divers now suspect, with warmer temperatures, the sharks may be around longer. Last year they were sighted up until June.
According to the divers, grey nurse sharks are thought to live between 30 and 40 years, grow to around 3.2 meters and are relatively slow to mature. Female sharks mature between 2.2 and 2.6 m at 9 to 10 years, while males mature between 1.9 and 2.2 m at 6 to 7 years of age. The females gestate for 9 to 12 months and give birth to one or two pups, which at birth pups are around 1 m in length, every two or three years.
Divers say because of the shark’s slow reproduction rate, grey nurse shark numbers are struggling to recover, which they say makes sanctuary/habitat protection zones critical. The national recovery plan has identified 19 known aggregation sites which are considered key for the survival of the East Coast population, Montague Island is the most southern of these sites.
While the divers say injuries sustained from accidental, incidental or illegal capture, both commercially and recreationally, and mortality related to shark control activities are understood to be the primary threats to the shark’s survival, local fishermen say most hooks used by recreational fishers rust out in a few weeks. Perhaps it is time to ban stainless steel hooks and shark nets?
Photographs featured in our online gallery show fishing gear is found in the sharks. It has been suggested that there should be Fisheries divers attempting to verify what local divers are seeing. If the sharks are here until June, then perhaps the restrictions on bait use should be extended. But, as always, we should use scientific data and not passion to make decisions.
While fishing attracts lots of dollars, so too do the natural wonders including the sharks. Without a healthy environment, we won’t have a healthy fishery and the sharks could be the canaries of the ocean. We probably have more to worry about from ocean warming and acidification than we do the use of bait on the north end.