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In 2001 fishermen and biologists reported large numbers of sharks in Sandy Hook Bay. Most were smooth dogfish but small thresher sharks and possibly a mako were spotted. Fishermen also reported fewer bluefish in the bay. Fishermen tend to keep gamefish and throw back trash fish (searobins, dogfish and skates). They may inadvertently alter the fish populations in the bay. | |
 Dogfish are commonly caught in
the evening but we found that they were biting during the day
throughout the summer and fall. |
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Dogfish feed on creatures like squid and don't need large teeth, so they are safe to handle. Shark skin is rough and has been used for leather and fine sand paper. In England, the fish in "fish and chips" is often "grey fish" which is the market name for the dogfish. Things to look for on the underside of a shark are the sensory organs like the ampullae of Lorenzini. | |
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The shark's eye is complex just like a human eye and can probably see as well as ours. The spiracle is located behind the eye. The roughness of the skin is made of dermal denticles, tiny toothlike scales. | |
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How do you tell the sex of a shark? A male shark has an extra set of clasper fins next to its pelvic fins. Dogfish can be handled easier than mako sharks, which can give a serious bite. The dogfish that we tagged (below left) were all safely returned to the water. Fishermen usually keep mako sharks (below right) to eat or to sell at the fish market. |
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Success! "Attitude is everything." We learned the three most important words in fishing: patience, patience and patience. A close up view of the shark reveals the lateral line, another sensory device used to detect movement and sound in the water. |
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This year we also found a number of parasitic isopods (crustaceans) on sharks and other fish. Some parasites are specific to certain fish. This isopod will be taken back to the lab for identification, and surprisingly it appears to be the genus Cymothoa, not Nerocila, which is more common on dogfish. Damage to the shark is probably insignificant but the parasite probably was attached for some time since it left a noticeable scar. |
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Sharks are fascinating creatures and play an important role in the marine ecosystem. After a hands-on introduction to sharks and a new appreciation of them, there is always an eager volunteer to give them a good luck kiss before we let them go. | |
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"Shadows in the Sea" by Harold W. McCormick and Tom Allen ISBN 0517179598 (includes a first hand account of the shark that terrorized the New Jersey coast and Sandy Hook Bay in 1916.) "Close to Shore" by Michael Capuzzo ISBN 0767904133 (the story of the shark attacks of 1916.) For programs on sharks and other marine life... and diving. Also visit www.sharks.org |
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| Plant and Animal checklists for your students. | ||
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For more information
about sharks: