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A. Longevity: Not much is known about the grwoth and age of sharks because many of the conventional methods of determining age won’t work. We know that sharks grow slowly compared to bony fish but growth rates vary between species. B. Studies on Shark Aging: The vertebrae of some sharks have growth rings deposited on them and this can be studied and compared with the growth rings of dead captive sharks. Sharks are also tagged, measured and released and when they are caught again the growth is measured and compared with the previous data. C. Predators: Several shark and batoid species have predators like other sharks, elephant seals and killer whales. D. Human Interaction: Sharks are very vulnerable to overfishing because they take long to reproduce and grow slow. Overfishing is due to an increased world market for shark products especially in Australia and the Far East. A way to stem overfishing is to set quotas on certains sharks, posession of a permit for shark fishing and that all unused, live sharks be returned to the sea without finning them. All the information about sharks can be used to set up effective fisheries management programs. |
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