Shark Identification for Cooperative Shark Tagging Program (A-B)
The Cooperative Shark Tagging Program is a collaborative effort between recreational anglers, the commercial fishing industry, and NOAA Fisheries to study the life history of Atlantic sharks. Sharks A - B
Overview
Accurate species identification is critical. To help with identifications we have provided information on size, distinguishing characteristics, distribution, and habitat for sharks in our region.
Atlantic Sharpnose Shark
Rhizoprionodon terraenovae
Lateral view of an Atlantic sharpnose shark.
Size
To about 4 ft (1.2 m).
Distinguishing Characteristics:
- Dorsal surfaces brownish-gray with scattered white spots in adults, white below; dorsal and caudal fins black-edged in juveniles
- Second dorsal fin originates over or behind midpoint of anal fin
- Mouth with long labial furrows around corners
- No interdorsal ridge
Distribution
New York to Florida, including the Gulf of Mexico, with strays north to New Brunswick, Canada.
Habitat
Coastal; shallow water ranging to 919 ft (280 m), often close to the surf zone; enclosed bays, sounds, harbors, marine to brackish estuaries.
Similar Species
Finetooth shark lacks white dorsal spots; it has second dorsal fin originating between origin and midpoint of anal fins. Blacknose shark lacks white dorsal spots; has dusky blotch at tip of snout. Smooth dogfish lacks white dorsal spots; has nearly equally sized dorsal fins, spiracles. Spiny dogfish lacks anal fin; has white spots on body, spines at origins of both dorsal fins.
Apex Predator Publications and Reports – Atlantic sharpnose shark
Management of Atlantic sharpnose shark
Basking Shark
Cetorhinus maximus
Lateral view of a basking shark.
Gill slits nearly circling the head of a basking shark.
Size
To about 32 ft (9.8 m).
Distinguishing Characteristics:
- Head nearly encircled with enormous gill slits; bristlelike gill rakers inside gill slits
- Color grayish-brown to slate gray above, often with lighter, irregular mottled patches; paler below
- Snout bulbous, conical
- Mouth large, subterminal; teeth minute and hooked
- Caudal fin lunate with single keel on caudal peduncle
Distribution
Newfoundland, Canada, to Florida; usually mid-Atlantic in spring; New England, Gulf of Maine, and Canada in summer.
Habitat
Coastal and offshore; sometimes enters inshore bays.
Similar Species
White shark has a dorsal surface that appears uniformly colored in the water, triangular teeth with serrated edges; lacks gill slits nearly encircling the head.
Apex Predator Publications and Reports – Basking shark
Bigeye Thresher Shark
Alopias superciliosus
Lateral view of a bigeye thresher shark's head.
Dorsal view of a bigeye thresher shark's head showing the deep grooves forming the "helmet".
Size
To about 15 ft (4.6 m).
Distinguishing Characteristics:
- Eyes large, directed upward
- Head with deep grooves on top forming "helmet"
- Caudal fin sickle-shaped, upper lobe extremely long (about 50 percent of total body length)
- Color dark purplish-brown or grayish-brown with dark metallic hues above; lighter coloring below, not extending above pectoral fin.
- First dorsal fin originating well behind free tips of pectoral fins
Distribution
New York to Cuba, including the Gulf of Mexico.
Habitat
Offshore at the edge of the continental shelf from the surface to 1,640 ft (500 m).
Similar Species
Common thresher shark has moderate-sized eyes directed laterally, white on abdomen extending above pectoral fins; lacks grooves on top of head.
Apex Predator Publications and Reports - Bigeye thresher shark
Bignose Shark
Carcharhinus altimus
Size
To about 9 ft (2.7 m).
Distinguishing Characteristics:
- Snout long and bluntly pointed to rounded, as long as or longer than width of mouth
- First dorsal fin large, originating over pectoral fin insertion to midlength of pectoral fin inner margin
- Pectoral fins long, nearly straight
- Color gray to grayish-brown above, white below
- Interdorsal ridge
Distribution
New Jersey to Venezuela, including the Gulf of Mexico and the Caribbean Sea.
Habitat
Offshore, deeper water near the edge of the continental shelf, 300-1,410 ft (91-430 m); bottom-dwelling; juveniles occasionally in shallower water up to 80 ft (24 m).
Similar Species
Sandbar shark, silky shark, and dusky shark have shorter snouts. Silky shark and dusky shark have first dorsal fins originating farther back, over or behind free tips of pectoral fins. Silky shark has a second dorsal fin with free-tip length usually more than twice fin height. Blacktip shark and bull shark lack interdorsal ridges.
Apex Predator Publications and Reports – Bignose shark
Blacknose Shark
Carcharhinus acronotus
Size
To about 4.5 ft (1.4 m).
Distinguishing Characteristics:
- Snout with dusky blotch at tip: distinct and dark in juveniles, diffuse and dusky in adults
- Color yellowish-gray or brown-to-greenish-gray above, yellowish or paler underside
- First dorsal fin small, originating over or behind free tips of pectoral fins
- No interdorsal ridge
Distribution
North Carolina to Brazil, including the Gulf of Mexico and Caribbean Sea.
Habitat
Inshore coastal waters over sandy, shell, or coral bottoms.
Similar Species
Atlantic sharpnose shark has scattered white spots on back and sides; lacks dusky blotch at tip of snout. Finetooth shark has more pointed snout, longer gills, bluish-gray color; lacks dusky blotch at tip of snout.
Apex Predator Publications and Reports – Blacknose shark
Blacktip Shark
Carcharhinus limbatus
Size
To about 6.5 ft (2m).
Distinguishing Characteristics:
- First and second dorsal fins, pectoral fins, and lower lobe of caudal fin black-tipped (black markings may fade in adults; maybe indistinct in juveniles).
- Anal fin white
- First dorsal fin fairly large with short free tip, originating slightly over or behind insertion of pectoral fins along inner margin, apex pointed
- Color dark gray, bluish-gray, to dusky bronze above, with light, conspicuous wedge-shaped band or Z-shaped line on sides beginning near pectoral fins, gradually widening rearward to pelvic fins to merge with white on belly
- No interdorsal ridge
Distribution
Massachusetts to Brazil, including the Gulf of Mexico and the Caribbean Sea. Rare north of Delaware.
Habitat
Shallow coastal and continental shelf waters; surface offshore. Common near river mouths, bays, and estuaries.
Similar Species
Sandbar shark, bignose shark, and silky shark have interdorsal ridges. Finetooth shark has unmarked fins. Spinner shark, most difficult to distinguish, has fairly small first dorsal fin originating at or just behind free tips of pectoral fins, black-tipped anal fin in specimens >2.6 ft (0.8m). Bull shark has a shorter snout, first dorsal fin rearward sloping; fins not usually black-tipped.
Apex Predator Publications and Reports – Blacktip shark
Blue Shark
Prionace glauca
Size
To about 12.5 ft (3.8 m).
Distinguishing Characteristics:
- Pectoral fins very long, narrow, pointed.
- Caudal fin non-lunate
- Body slender
- Snout rounded, long
- Color dark blue above, bright blue with metallic hues on sides, white underside
- First dorsal fin closer to pelvic fins than to pectoral fins
Distribution
Newfoundland, Canada, to Argentina, including the Gulf of Mexico and the Caribbean Sea. Common in the U.S. Northeast and Mid-Atlantic.
Habitat
Offshore; relatively cool waters 45-70°F (7-21°C); surface to about 1,970 ft (600 m).
Similar Species
Shortfin mako and longfin mako have more pointed snouts, protruding smooth-edged teeth, stouter bodies, lunate caudal fins, strong caudal keels.
Size
To about 5 ft (1.5 m).
Distinguishing Characteristics:
- Head shovel-shaped, lacking indentation at midline, evenly rounded between eyes.
- Back and sides often with scattered small dark spots.
- Color gray, tan, or greenish above, paler below.
- No interdorsal ridge.
Distribution
North Carolina to Brazil, including the Gulf of Mexico and Caribbean Sea. Rare to Rhode Island.
Habitat
Warm, shallow coastal waters over sandy and muddy bottoms, coral reefs, and grass flats; common in bays and estuaries.
Similar Species
Scalloped hammerhead, great hammerhead, and smooth hammerhead attain greater maximum size; have hammer-shaped, not shovel-shaped, heads.
Apex Predator Publications and Reports – Bonnethead shark
Bull Shark
Carcharhinus leucas
Size
To about 11.5 ft (3.5 m).
Distinguishing Characteristics:
- First dorsal fin large, triangular, rearward sloping, originating over or slightly behind pectoral insertion
- Snout much shorter than width of mouth and bluntly rounded
- Eyes small
- Body stocky to heavy, especially in adults
- Color pale to dark gray above, white below
- No interdorsal ridge
Distribution
New York to Brazil, including the Gulf of Mexico and Caribbean Sea. Rare north of Delaware.
Habitat
Primarily shallow coastal water; common in lagoons, bays, river mouths; often enters far into fresh water.
Similar Species
Sandbar shark, dusky shark, and bignose shark have interdorsal ridges; do not occur in freshwater. Sandbar shark and blacktip shark have first dorsal fins that are erect, not rearward sloping. Blacktip shark has black-tipped fins; does not occur in freshwater.
Apex Predator Publications and Reports – Bull shark
Other Species
- Shark Identification for Cooperative Shark Tagging Program (C-P)
- Shark Identification for Cooperative Shark Tagging Program (S-W)