Mary Syrett - April 2011

 

The Bay's Quiet Shark
by
Mary Syrett

Many people are familiar with Peter Benchley’s novel Jaws or one of the movies it inspired. The image of a giant shark terrorizing a beach community is hard to forget. After all, the idea of predators (in this case, people) becoming prey realizes one of our most basic primal fears. It also makes for exciting reading and viewing.
Fortunately, actual shark attacks are rare. In fact, few species of shark are considered dangerous to man, and the poor reputation sharks have acquired is a result of fear and ignorance rather than anything having to do with scientific fact.
The Tidewater’s coastal waters harbor a rich diversity of marine life. Included in this diversity are several species of shark, including the sandbar shark.
Sandbar sharks: Carcharhinus plumbeus – the genus name Carcharhinus is derived from the Greek “karcharos,” meaning to sharpen, and “rhinos,” referring to the nose. The species name plumbeus is translated from Latin as “of lead.” Thus, literally, the sandbar’s name means “sharpened nose of lead.”
Sandbars live in temperate and tropical waters around the world. They grow slowly, their body is made up entirely of cartilage and they begin reproducing at around ten years of age. Females can live as long as 21 years and males 15.
Adults have saw-like teeth, a rounded snout, a tall, triangular huge first dorsal fin and the thick, narrow ridge of skin running along the back between the two dorsal fins.
Sandbar sharks can grow to about seven feet long, but the young that live in Chesapeake Bay are two to three feet in length. Males and females lead separate lives and meet only during summer migrations in May and June. Sandbar sharks are one of the few fish that give birth to live young.
Where Found. The sandbar shark has a global distribution. It is found in the Western and Eastern Atlantic, including the Mediterranean. In the Indo-Pacific region it ranges from the Persian Gulf, Red Sea, and southern Africa to Hawaii.
The creature is a bottom dweller, rarely seen on the surf unless in extremely shallow water. Sandbars are particularly fond of harbors, estuaries and other shallow inshore areas.
Also sometimes called the brown shark, the sandbar is one of the biggest coastal sharks in the world and is closely related to the bull shark. Body color can range from bluish to a brownish gray to bronze, with a white or pale underside. They are most active at night, at dawn and at dusk.
Sharks are somewhat like dogs; even within one species, there are different personalities. Some sandbar sharks can be downright shy, while others are inquisitive and aggressive.
How do sandbar sharks reproduce? They are different from most other fish because females give birth to live young. After carrying them for 12 months, a female sandbar shark gives birth to nine or ten live young.
The sandbar shark seeks out muddy or sandy bottoms in shallow coastal waters such as bays, estuaries, harbors and river mouths. Large schools of juveniles visit the Chesapeake Bay in the summer and fall. They are most often found in shallow grass beds.
Sandbar sharks usually stay in the Virginia portion of the Bay, though some do occasionally move northward into Maryland waters. In the fall, many leave Chesapeake Bay for warmer waters to the south.
Diet. The creatures dine on blue crabs, as well as sardines, shad, menhaden, eels, barracuda, mackerel, grouper, croaker, flounder, skates, stingrays, squid, shrimp, mollusks, cuttlefish and octopus.
Going, Going...? Everywhere in the world, sharks are an important part of fishery catches, both professional and amateur. On the U.S. Atlantic coast, sharks constitute some 60 percent of the bycatch found in fishing nets. As for sportfishing, sandbar shark catches are second only to blue marlin in terms of popularity. With high capture rates and given that these creatures reproduce only later in life, this shark has become quite rare in many parts of the world.
John A. Musick, a recognized expert on sharks associated with the Virginia Institute of Marine Science, points out that the decline in sandbar shark populations began in earnest in the 1980s as a result of a popular cultural phenomenon. “After the movie Jaws came out in 1975, recreational fishing for sharks exploded.” According to Musick, “sandbar populations today are only 20 to 30 percent of what they were in the 1970s.”
Sharks are harvested for their meat (for human consumption), as well as for their hides and livers, which are highly valued for the vitamin-rich oil that shark livers possess.
Many Chesapeake Bay watermen today target sandbar sharks because the meat and fins bring in a good price at a time when making a living from the water is becoming increasingly difficult. Regular shark meat costs around $6.95 per pound in markets on the U.S. East Coast. But in Hong Kong and other Asian markets, where shark fin soup is a highly sought delicacy, shark fins can bring in at least $200 per pound. Add that demand to the fact that a sandbar’s flesh and large fins are particularly tasty, and it becomes clear that economic factors have not been good for this creature, whose numbers have been declining for three decades.
Commercial shark fishing is unsustainable. The sandbar shark population, which is a primary target of commercial shark fishermen, is projected to take at least 70 years to rebuild while allowing only limited catches. Over-fishing, spurred by rising prices and insatiable demand, is blamed for a significant drop in shark populations. Because of fear of over-fishing and potential heavy fines that come with it, most watermen are skittish about going into detail concerning the monetary values associated with shark fishing in Chesapeake Bay.
Sharks are important ecologically because they sit atop the food chain as apex predators. As such, they play a significant role in keeping prey populations healthy by removing the weak, old and infirm. As shark populations continue declining due to over-fishing and habitat loss, prey populations are likely to increase unchecked, leading to an overall general decline in ecosystem health.
The sandbar shark suffers from an unfortunate case of mixed identities. It has had at least 10 scientific names since the early 1800s and half as many common names. Quiet, seldom seen, rarely studied and a bit mysterious, sandbar sharks form a link with the primordial past. We should pray that this magnificent creature will forever remain with us and contribute to the wonders of Chesapeake Bay, as well as many other water places on God’s green earth.