Blog Tags: Juvenile Sharks
Whether you fear them or admire them, most people have an instant reaction when they hear great white shark.
Intrigue, mystery, and terror have guided attention on great white sharks since they lit up the screens in the 1975 thriller “Jaws.” The film made history 37 years ago for its chilling characterization of these powerful sharks, and swimming in the open ocean has never been the same since.
Great whites are making history once again, this time for their globally declining populations from bycatch in commercial fisheries, capture in beach protective nets, and slaughter for their fins, teeth, and jaws in the shark fin and curio trade.
Here on the US West Coast, new scientific studies have shed light on the status of great white sharks off California and Baja California, Mexico. Our great white sharks are even more unique than we thought; in fact they are genetically distinct and isolated from all other great white sharks around the world. They congregate off Mexican Islands and the “red triangle” off Central California (including the Farallon Islands, Point Reyes, and Point Sur), and make extensive offshore migrations to the distant “white shark Café” and even to the Hawaiian Islands.
But, sadly there may be as little as a few hundred adult great white sharks remaining in this population, far less than anyone expected. This low population alone puts these great whites at great risk of extinction from natural and human-caused impacts. Continued existence of these West Coast great white sharks is threatened by their low population size, inherent vulnerability to capture, slow growth rate, low reproductive output, and the ongoing threats they face from human activities. This is why Oceana is petitioning the federal government and the state of California to list this population of iconic sharks on the Endangered Species List.
What is threatening great white sharks off California and Mexico?
Young great white sharks are un-intentionally caught as bycatch in commercial fishing entangling nets. Set and drift gillnets--which together target California halibut, yellowtail, white seabass, thresher sharks and swordfish--catch great white shark pups in their nursery grounds.
Since 1980, over 10 great white shark pups have been reported being caught in these nets every year. The scary part is that monitoring of bycatch on these fishing vessels is very low so take of these pups remains underreported. In other words, more great white sharks are caught than we are aware.
Additionally, young great white shark “pups” caught in their nursery grounds off the Southern California coast have the second highest mercury level tested on record for any sharks worldwide. These mercury levels exceed six-fold the established thresholds where harmful physiological effects have been documented in other marine fish. Levels of harmful contaminants of PCBs and DDTs in their liver tissue are the highest observed in any shark species reported to date globally.
Endangered species status will bestow additional protections to white sharks, including better monitoring and management to reduce fishery bycatch and additional research to further understand these fascinating top predators of the sea.
As much as we may fear them for their bad rap, we need great white sharks to keep our oceans healthy. Just as wolves keep deer populations under control, great white sharks play a critical top-down role in structuring the marine ecosystem by keeping prey populations in check, such as sea lions and elephant seals, benefiting our fisheries and abundant wildlife.
Listing the West Coast population of great white sharks on the Endangered Species List will help us learn more about the lives and threats of these amazing animals through additional research funding and protection measures.
Please help us in our efforts to protect US West Coast great white sharks from extinction by signing a letter of support for their listing on the Endangered Species Act.
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