- Although the flesh of the almaco jack is considered quality table fare, the species has been associated with ciguatera poisoning, a seldom fatal stomach irritation.
- The almaco jack is susceptible to tapeworm parasites in the caudal peduncle area, but the meat can be eaten safely if affected portions are cut away.
Sandbar shark (Carcharhinus)
Sandbar sharks are sturdy, plain looking requiem sharks that are most easily identified by their high first dorsal fin. They are a cartilaginous fish, meaning they have a skeleton made of cartilage, and are related to the dusky, bignose and bull sharks. Relatively speaking, they are a medium to large shark and are among the larger coastal sharks.
The vast majority of sandbar sharks are brown-gray in color dorsally, although small numbers may be dark blue-gray or bronze. Occasionally, the color will have a bit of metallic shine to it. The ventral side, or bottom, is a very pale gray or white color. There is no major color difference on the fins, though they often have a dark shadow-like tinting on the fin tips. There are no significant markings on the body, though there is sometimes a darker, nearly invisible, horizontal stripe on the underside.
Sandbar sharks have a strong build that culminates in a flat head with a blunt, rounded snout. Both the upper and lower teeth are extremely sharp and have jagged edges. The upper teeth are somewhat triangular in shape, and the lower teeth are smaller and less jagged. The nostrils are relatively short. On the body, there is a ridge that runs between the two dorsal fins.
The first dorsal fin is triangular in shape and very tall with a slightly rounded apex. The second dorsal fin is smaller, though it too is relatively large. The pectoral fins are also rather large and curvilinear.
Sandbar sharks are nearly identical to the dusky shark and thus often confused. However similar they may be, the dusky shark can grow to over three times the size of a sandbar shark, making confusion of adults unlikely.
Sandbar sharks feed primarily on small, bony fish. However, they will also consume smaller sharks, rays, cephalopods, gastropods and amphipods. Their favored foods include fish such as sardine, shad, menhaden, anchovies, barracuda, moray eel, mullet, mackerel, bonito, jack, grouper, porgy, flounder, sole, bonnethead shark, guitarfish and rays. They diversify their diet with squid, octopus, shrimp, crabs and conch. Unlike other shark species, they will not ordinarily eat trash or carrion. Primarily a predator, they can also scavenge when necessary. Most of their feeding activity occurs near the bottom. They feed day and night, though activity increases at night.
Sandbar sharks are found in every major saltwater body in the world in both inshore and offshore coastal areas with temperate to tropical water temperatures. These areas include the Atlantic, Pacific and Indian Oceans, as well as the Caribbean and Mediterranean Seas.
In the western Atlantic, sandbar sharks are found along the coast of such places as Massachusetts, Chesapeake Bay, Florida, the Gulf of Mexico, the Bahamas, Cuba, Nicaragua, Costa Rica, Venezuela and Brazil. In the eastern Atlantic, they reside in waters around Spain, Portugal, the Canary Islands, Morocco, Senegal, the Cape Verde Islands, the Gulf of Guinea and Zaire. They are also found throughout the region of the Mediterranean, including near Libya, Egypt, the Sicilian Channel, the west coast of Italy, Malta and the Aegean Sea.
Within the Indian Ocean, sandbar sharks are most common around South Africa, Madagascar, Mozambique, Mauritius, Tanzania, the Seychelles, the Red Sea, the Gulf of Oman and the Persian Gulf.
Sandbar sharks are widely distributed in the Pacific Ocean and range from Australia to New Caledonia, Indonesia, Vietnam, Korea, China, Taiwan and Japan. They are also common around the Hawaiian Islands and the Galapagos Islands.
Sandbar sharks can be found inshore or offshore. They are an exclusively marine species that reside in tropical and temperate waters, though they will venture into shallow water and river estuaries. Generally, they favor areas over the continental shelf, around oceanic banks and near island mounts. They are quite often found just outside the breakers in shallow to medium depth water. It is not unusual, however, to see them in bays, harbors or estuaries, nor in deep ocean water.
It is speculated that they prefer smooth sandy bottoms and it is apparent that they avoid rough areas around surf zones and reefs. Also, they seldom are found directly at the surface. The greatest number of sand sharks are found in waters with temperatures between 72 and 81 F. Typically they roam at depths of 60 to 200 feet, though they have been known to come into water so shallow their fins protrude from the water or as deep as 800 feet or more.
Though there appear to be some sandbar shark populations that permanently reside in areas around the world, most populations engage in long migrations. These migrations seem to be triggered by a combination of seasonal changes in temperature and current patterns. These migrations can vary in distance depending on location, but distances of over 1,500 miles have been documented. Generally, males migrate earlier and at greater depths than females. In addition, males travel in large schools, sometimes numbering in the hundreds, while females tend to migrate individually or in very small groups.
Sandbar shark groups are also segregated by age. While young sandbar sharks develop mixed-sex schools, adults are separated into separate male and female groups.
- Sandbar sharks have no natural enemies, though great white sharks prey upon young sandbar sharks.
- Sandbar sharks are not considered a threat to humans, despite their size.
- As a cartilaginous fish, sandbar sharks have no swim bladder and must remain in constant motion to stay afloat. This constant movement assists the shark in moving oxygenated blood through the body.