Finetooth shark
Encyclopedia
The finetooth shark is a species
of requiem shark
, family
Carcharhinidae, found in the western Atlantic Ocean
from North Carolina
to Brazil
. It forms large schools
in shallow, coastal waters and migrate
s seasonally following warm water. A relatively small, slender-bodied shark, the finetooth shark can be identified by its needle-like teeth, dark blue-gray dorsal coloration, and long gill slit
s. It attains a maximum length of 1.9 m (6.2 ft). The diet of this species consists primarily of small bony fishes, in particular menhaden
. Like other members of its family, it is viviparous with females giving birth to 2–6 pups in estuarine
nursery areas every other year.
Valued for its meat, the finetooth shark forms an important component of the commercial
gillnet
shark fishery
operating off the southeastern United States
. Population assessments suggest that this fishery does not currently pose a threat to U.S. populations of the species. The International Union for Conservation of Nature (IUCN) has therefore listed the finetooth shark under Least Concern
, though there is no fishery data available for this species off South America. This shark is not known to pose a danger to humans, though it snaps vigorously when captured and should be handled with caution.
, in Müller
and Henle's 1839 Systematische Beschreibung der Plagiostomen. The type specimen is a 65 cm (25.6 in) juvenile male, possibly caught off the U.S. state
of New York
. This species was later moved to the genus Carcharhinus. The specific epithet isodon means "equal teeth" in Greek, and refers to the similar number of teeth in the upper and lower jaws. This species may also be referred to as the eventooth shark, smoothtooth shark, or night shark (usually used for C. signatus
).
As is the case for most Carcharhinus species, attempts to analyze the finetooth shark's phylogenetic relationships have yielded variable results. In 1988, Leonard Compagno
grouped this species with the spinner shark
(C. brevipinna), blacktip shark
(C. limbatus), graceful shark
(C. amblyrhynchoides), and the smooth tooth blacktip shark
(C. leiodon), on the basis of morphological
characters. Gavin Naylor's 1992 allozyme
analysis found that the finetooth shark is the second-most basal
member of the genus next to the blacknose shark
(C. acronotus). Mine Dosay-Akbulut's 2008 study, based on ribosomal DNA
, suggested that the closest relative of the finetooth shark is the smalltail shark
(C. porosus), and that the two species form a clade
apart from other Carcharhinus species.
to the northern Gulf of Mexico
, and very occasionally straying as far north as New York. In Central and South American waters, it is rare but may occur more widely than presently known, having been reported off Trinidad
and Guyana
, infrequently from the Caribbean Sea
, and off southern Brazil
from São Paulo
to Santa Catarina
. The northwestern Atlantic, Gulf of Mexico, and South America populations are distinct, with little interchange between them. There are old records of this species in the eastern Atlantic off Senegal
and Guinea-Bissau
, but these likely represent misidentifications of spinner shark
s (C. brevipinna).
An inhabitant of coastal habitat
s, the finetooth shark is often found near beach
es and in bay
s and estuaries. It ranges no deeper than 10 m (32.8 ft) deep in the summer and 20 m (65.6 ft) deep in the winter. Historically it was known to venture into rivers in the Gulf Coastal Plain
of Texas
, though most of paths into this area are now blocked by dam
s. The northwestern Atlantic population of this species is strongly migratory
: juveniles, followed by adults, arrive off South Carolina
from late March to early May, when the water temperature rises above 20 °C (68 °F). They remain until September to mid-October, at which point the water temperature drops and they move south to Florida
. The movements of other populations are unknown.
s (protective third eyelid
s). The mouth is broad with well-defined furrows at the corners. There are 12–15 tooth rows on either side of the upper jaw and 13–14 tooth rows on either side of the lower jaw. Each tooth is small and needle-like, with a narrow central cusp and smooth to minutely serrated edges. The five pairs of gill slits are long, measuring about half the length of the dorsal fin
base.
The first dorsal fin is high and triangular with a pointed apex, originating forward of the free rear tips of the pectoral fins. The second dorsal fin is relatively large and originates over the anal fin. There is no ridge running between the dorsal fins. The pectoral fins are small and falcate (sickle-shaped), with pointed tips. The dermal denticles are small and overlapping, each bearing three horizontal ridges leading to marginal teeth. Living finetooth sharks are a distinctive dark bluish-gray above and white below, with a faint pale stripe on the flanks and no prominent fin markings. Some individuals from Florida have green eyes. Males average 1.6 m (5.2 ft) in length and females 1.7 m (5.4 ft); the largest shark on record was 1.9 m (6.2 ft) long.
. This energetic, fast-moving predator feeds mainly on small bony fishes, often entering the surf zone
during the day to hunt. The most important prey of this species in the northwestern Atlantic is the Atlantic menhaden
(Brevoortia tyrannus), with sharks of all ages off northwestern Florida eat almost nothing else. The menhaden are swallowed whole after the head has been removed. Other known prey species include spot croaker
(Leiostomus xanthurus), Spanish mackerel (Scomberomorus maculatus), mullet
(Mugil spp.), shrimp
, and in one case a juvenile Atlantic sharpnose shark
(Rhizoprionodon terraenovae), which may have been scavenged
from the bycatch
discard of a shrimp trawler. The finetooth shark may be preyed upon by larger sharks.
s are nourished by yolk for the first 15 weeks, after which the depleted yolk sac
develops into a placenta
l connection to the mother. Females produce litters of 2–6 pups every other year. In the northwestern Atlantic, mating occurs from early May to early June and the young are born at around the same time the following year after a 12-month gestation period
. The males bite at the female to hold her for copulation. The semen
exuded by the male congeals into a large spongy mass inside the female's uterus
, in which the individual spermatozoa are embedded. Called a "spermatozeugma", the function of this short-lived structure is unknown. Newborn finetooth sharks measure 48–64 cm (18.9–25.2 in) long. Shallow bays and estuaries, such as Bull's Bay in South Carolina, serve as critical nursery areas for newborns and juveniles.
Female finetooth sharks grow much more slowly and to a larger ultimate size than males. Individuals in the northwestern Atlantic population have a larger body size and reach sexual maturation later than those in the Gulf of Mexico population; males in the two populations grow at similar rates, but northwestern Atlantic females grow more slowly than Gulf of Mexico females. In the northwestern Atlantic, males mature at a fork length (length from snout tip to caudal fin fork) of 99 cm (39 in) and females at 102 cm (40.2 in), corresponding to ages of 5 and 6 years respectively. In the Gulf of Mexico, males mature at a fork length of 94 cm (37 in) and females at 99 cm (39 in), corresponding to ages of 4 and 5 years respectively. The maximum lifespan has been estimated to be at least 9 years for males and 14 years for females.
due to its low reproductive rate, and to habitat degradation due to its inshore habits.
Substantial numbers of finetooth sharks are caught in drift gillnet
s operated by the shark fishery off southeastern United States, which peaked in 1999 at about 117 tons landed. Stock assessments conducted in 2002 suggested that U.S. populations had not yet been overfish
ed but that the catch rate was unsustainable, whereas assessments conducted in 2007 concluded that catch rates did not exceed sustainable levels and that populations were stable. Fishing for this species in U.S. waters is regulated by the National Marine Fisheries Service
(NMFS) 1993 Fisheries Management Plan (FMP) for Atlantic and Gulf of Mexico sharks; it is classified as a "Small Coastal Shark" (SCS) for the purposes of commercial quotas and recreational bag limits. As a result, the International Union for Conservation of Nature (IUCN) has assessed the finetooth shark as of Least Concern
overall and off the U.S. and Mexico. There is concern for this species in South America, where its numbers seem naturally low and it is potentially under heavy pressure by widespread, intensive coastal fisheries. However, at present the IUCN does not have sufficient data to assess its status in the region beyond Data Deficient
.
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
of requiem shark
Requiem shark
Requiem sharks are a family, Carcharhinidae, of sharks in the order Carcharhiniformes, containing migratory, live-bearing sharks of warm seas such as the tiger shark, the blue shark, the bull shark, and the milk shark.The name may be related to the French word for shark, "requin", itself of...
, family
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
Carcharhinidae, found in the western Atlantic Ocean
Atlantic Ocean
The Atlantic Ocean is the second-largest of the world's oceanic divisions. With a total area of about , it covers approximately 20% of the Earth's surface and about 26% of its water surface area...
from North Carolina
North Carolina
North Carolina is a state located in the southeastern United States. The state borders South Carolina and Georgia to the south, Tennessee to the west and Virginia to the north. North Carolina contains 100 counties. Its capital is Raleigh, and its largest city is Charlotte...
to Brazil
Brazil
Brazil , officially the Federative Republic of Brazil , is the largest country in South America. It is the world's fifth largest country, both by geographical area and by population with over 192 million people...
. It forms large schools
Shoaling and schooling
In biology, any group of fish that stay together for social reasons are said to be shoaling , and if, in addition, the group is swimming in the same direction in a coordinated manner, they are said to be schooling . In common usage, the terms are sometimes used rather loosely...
in shallow, coastal waters and migrate
Fish migration
Many types of fish migrate on a regular basis, on time scales ranging from daily to annually or longer, and over distances ranging from a few metres to thousands of kilometres...
s seasonally following warm water. A relatively small, slender-bodied shark, the finetooth shark can be identified by its needle-like teeth, dark blue-gray dorsal coloration, and long gill slit
Gill slit
Gill slits are individual openings to gills, i.e., multiple gill arches, which lack a single outer cover. Such gills are characteristic of Cartilaginous fish such as sharks, rays, sawfish, and guitarfish. Most of these have five pairs, but a few species have 6 or 7 pairs...
s. It attains a maximum length of 1.9 m (6.2 ft). The diet of this species consists primarily of small bony fishes, in particular menhaden
Menhaden
Menhaden, also known as mossbunker, bunker and pogy, are forage fish of the genera Brevoortia and Ethmidium, two genera of marine fish in the family Clupeidae.-Description:...
. Like other members of its family, it is viviparous with females giving birth to 2–6 pups in estuarine
Estuary
An estuary is a partly enclosed coastal body of water with one or more rivers or streams flowing into it, and with a free connection to the open sea....
nursery areas every other year.
Valued for its meat, the finetooth shark forms an important component of the commercial
Commercial fishing
Commercial fishing is the activity of catching fish and other seafood for commercial profit, mostly from wild fisheries. It provides a large quantity of food to many countries around the world, but those who practice it as an industry must often pursue fish far into the ocean under adverse conditions...
gillnet
Gillnet
Gillnetting is a common fishing method used by commercial and artisanal fishermen of all the oceans and in some freshwater and estuary areas. The gillnet also is used by fisheries scientists to monitor fish populations. Because gillnets can be so effective their use is closely monitored and...
shark fishery
Fishery
Generally, a fishery is an entity engaged in raising or harvesting fish which is determined by some authority to be a fishery. According to the FAO, a fishery is typically defined in terms of the "people involved, species or type of fish, area of water or seabed, method of fishing, class of boats,...
operating off the southeastern United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
. Population assessments suggest that this fishery does not currently pose a threat to U.S. populations of the species. The International Union for Conservation of Nature (IUCN) has therefore listed the finetooth shark under Least Concern
Least Concern
Least Concern is an IUCN category assigned to extant taxon or lower taxa which have been evaluated but do not qualify for any other category. As such they do not qualify as threatened, Near Threatened, or Conservation Dependent...
, though there is no fishery data available for this species off South America. This shark is not known to pose a danger to humans, though it snaps vigorously when captured and should be handled with caution.
Taxonomy and phylogeny
The finetooth shark was originally described as Carcharias (Aprion) isodon by French zoologist Achille ValenciennesAchille Valenciennes
Achille Valenciennes was a French zoologist.Valenciennes was born in Paris, and studied under Georges Cuvier. Valenciennes' study of parasitic worms in humans made an important contribution to the study of parasitology...
, in Müller
Johannes Peter Müller
Johannes Peter Müller , was a German physiologist, comparative anatomist, and ichthyologist not only known for his discoveries but also for his ability to synthesize knowledge.-Early years and education:...
and Henle's 1839 Systematische Beschreibung der Plagiostomen. The type specimen is a 65 cm (25.6 in) juvenile male, possibly caught off the U.S. state
U.S. state
A U.S. state is any one of the 50 federated states of the United States of America that share sovereignty with the federal government. Because of this shared sovereignty, an American is a citizen both of the federal entity and of his or her state of domicile. Four states use the official title of...
of New York
New York
New York is a state in the Northeastern region of the United States. It is the nation's third most populous state. New York is bordered by New Jersey and Pennsylvania to the south, and by Connecticut, Massachusetts and Vermont to the east...
. This species was later moved to the genus Carcharhinus. The specific epithet isodon means "equal teeth" in Greek, and refers to the similar number of teeth in the upper and lower jaws. This species may also be referred to as the eventooth shark, smoothtooth shark, or night shark (usually used for C. signatus
Night shark
The night shark is a species of requiem shark, family Carcharhinidae, found in the temperate and tropical waters of the Atlantic Ocean...
).
As is the case for most Carcharhinus species, attempts to analyze the finetooth shark's phylogenetic relationships have yielded variable results. In 1988, Leonard Compagno
Leonard Compagno
Leonard Joseph Victor Compagno is an international authority on shark taxonomy and the author of many scientific papers and books on the subject, best known of which is his 1984 catalogue of shark species produced for the Food and Agriculture Organization of the United Nations.-Career:*Ph.D,...
grouped this species with the spinner shark
Spinner shark
The spinner shark is a species of requiem shark, family Carcharhinidae, named for the spinning leaps it makes as a part of its feeding strategy. This species occurs in tropical and warm temperate waters worldwide, except for in the eastern Pacific Ocean...
(C. brevipinna), blacktip shark
Blacktip shark
The blacktip shark is a species of requiem shark, family Carcharhinidae. It is common to coastal tropical and subtropical waters around the world, including brackish habitats. Genetic analyses have revealed substantial variation within this species, with populations from the western Atlantic Ocean...
(C. limbatus), graceful shark
Graceful shark
The graceful shark or Queensland shark is a species of requiem shark, family Carcharhinidae, found in the tropical Indo-Pacific from the Gulf of Aden to northern Australia. It is a midwater species that has been recorded to a depth of...
(C. amblyrhynchoides), and the smooth tooth blacktip shark
Smooth tooth blacktip shark
The smoothtooth blacktip shark is a species of requiem shark, family Carcharhinidae, known only from a single immature specimen from the Gulf of Aden. It resembles the blacktip reef shark in shape and color, having black tips on all fins, but has a more pointed snout and narrow, smooth-edged...
(C. leiodon), on the basis of morphological
Morphology (biology)
In biology, morphology is a branch of bioscience dealing with the study of the form and structure of organisms and their specific structural features....
characters. Gavin Naylor's 1992 allozyme
Allozyme
Variant forms of an enzyme that are coded by different alleles at the same locus are called allozymes. These are opposed to isozymes, which are enzymes that perform the same function, but which are coded by genes located at different loci....
analysis found that the finetooth shark is the second-most basal
Basal (phylogenetics)
In phylogenetics, a basal clade is the earliest clade to branch in a larger clade; it appears at the base of a cladogram.A basal group forms an outgroup to the rest of the clade, such as in the following example:...
member of the genus next to the blacknose shark
Blacknose shark
The blacknose shark is a species of requiem shark, family Carcharhinidae, common in the tropical and subtropical waters of the western Atlantic Ocean. This species generally inhabits coastal seagrass, sand, or rubble habitats, with adults preferring deeper water than juveniles...
(C. acronotus). Mine Dosay-Akbulut's 2008 study, based on ribosomal DNA
Ribosomal DNA
Ribosomal DNA codes for ribosomal RNA. The ribosome is an intracellular macromolecule that produces proteins or polypeptide chains. The ribosome itself consists of a composite of proteins and RNA. As shown in the figure, rDNA consists of a tandem repeat of a unit segment, an operon, composed of...
, suggested that the closest relative of the finetooth shark is the smalltail shark
Smalltail shark
The smalltail shark is a species of requiem shark, family Carcharhinidae, found in the western Atlantic Ocean from the northern Gulf of Mexico to southern Brazil. It inhabits shallow waters close to shore, particularly over muddy bottoms around estuaries. It tends to swim low in the water column...
(C. porosus), and that the two species form a clade
Clade
A clade is a group consisting of a species and all its descendants. In the terms of biological systematics, a clade is a single "branch" on the "tree of life". The idea that such a "natural group" of organisms should be grouped together and given a taxonomic name is central to biological...
apart from other Carcharhinus species.
Distribution and habitat
In North American waters, the finetooth shark is common and found from North CarolinaNorth Carolina
North Carolina is a state located in the southeastern United States. The state borders South Carolina and Georgia to the south, Tennessee to the west and Virginia to the north. North Carolina contains 100 counties. Its capital is Raleigh, and its largest city is Charlotte...
to the northern Gulf of Mexico
Gulf of Mexico
The Gulf of Mexico is a partially landlocked ocean basin largely surrounded by the North American continent and the island of Cuba. It is bounded on the northeast, north and northwest by the Gulf Coast of the United States, on the southwest and south by Mexico, and on the southeast by Cuba. In...
, and very occasionally straying as far north as New York. In Central and South American waters, it is rare but may occur more widely than presently known, having been reported off Trinidad
Trinidad
Trinidad is the larger and more populous of the two major islands and numerous landforms which make up the island nation of Trinidad and Tobago. It is the southernmost island in the Caribbean and lies just off the northeastern coast of Venezuela. With an area of it is also the fifth largest in...
and Guyana
Guyana
Guyana , officially the Co-operative Republic of Guyana, previously the colony of British Guiana, is a sovereign state on the northern coast of South America that is culturally part of the Anglophone Caribbean. Guyana was a former colony of the Dutch and of the British...
, infrequently from the Caribbean Sea
Caribbean Sea
The Caribbean Sea is a sea of the Atlantic Ocean located in the tropics of the Western hemisphere. It is bounded by Mexico and Central America to the west and southwest, to the north by the Greater Antilles, and to the east by the Lesser Antilles....
, and off southern Brazil
Brazil
Brazil , officially the Federative Republic of Brazil , is the largest country in South America. It is the world's fifth largest country, both by geographical area and by population with over 192 million people...
from São Paulo
São Paulo (state)
São Paulo is a state in Brazil. It is the major industrial and economic powerhouse of the Brazilian economy. Named after Saint Paul, São Paulo has the largest population, industrial complex, and economic production in the country. It is the richest state in Brazil...
to Santa Catarina
Santa Catarina (state)
Santa Catarina is a state in southern Brazil with one of the highest standards of living in Latin America. Its capital is Florianópolis, which mostly lies on the Santa Catarina Island. Neighbouring states are Rio Grande do Sul to the south and Paraná to the north. It is bounded on the east by...
. The northwestern Atlantic, Gulf of Mexico, and South America populations are distinct, with little interchange between them. There are old records of this species in the eastern Atlantic off Senegal
Senegal
Senegal , officially the Republic of Senegal , is a country in western Africa. It owes its name to the Sénégal River that borders it to the east and north...
and Guinea-Bissau
Guinea-Bissau
The Republic of Guinea-Bissau is a country in West Africa. It is bordered by Senegal to the north, and Guinea to the south and east, with the Atlantic Ocean to its west....
, but these likely represent misidentifications of spinner shark
Spinner shark
The spinner shark is a species of requiem shark, family Carcharhinidae, named for the spinning leaps it makes as a part of its feeding strategy. This species occurs in tropical and warm temperate waters worldwide, except for in the eastern Pacific Ocean...
s (C. brevipinna).
An inhabitant of coastal habitat
Habitat
* Habitat , a place where a species lives and grows*Human habitat, a place where humans live, work or play** Space habitat, a space station intended as a permanent settlement...
s, the finetooth shark is often found near beach
Beach
A beach is a geological landform along the shoreline of an ocean, sea, lake or river. It usually consists of loose particles which are often composed of rock, such as sand, gravel, shingle, pebbles or cobblestones...
es and in bay
Bay
A bay is an area of water mostly surrounded by land. Bays generally have calmer waters than the surrounding sea, due to the surrounding land blocking some waves and often reducing winds. Bays also exist as an inlet in a lake or pond. A large bay may be called a gulf, a sea, a sound, or a bight...
s and estuaries. It ranges no deeper than 10 m (32.8 ft) deep in the summer and 20 m (65.6 ft) deep in the winter. Historically it was known to venture into rivers in the Gulf Coastal Plain
Gulf Coastal Plain
The Gulf Coastal Plain extends around the Gulf of Mexico in the Southern United States and eastern Mexico.The plain reaches from the western Florida Panhandle, the southwestern two thirds of Alabama, over most of Mississippi, some of western Tennessee and Kentucky, southwest Arkansas, the Florida...
of Texas
Texas
Texas is the second largest U.S. state by both area and population, and the largest state by area in the contiguous United States.The name, based on the Caddo word "Tejas" meaning "friends" or "allies", was applied by the Spanish to the Caddo themselves and to the region of their settlement in...
, though most of paths into this area are now blocked by dam
Dam
A dam is a barrier that impounds water or underground streams. Dams generally serve the primary purpose of retaining water, while other structures such as floodgates or levees are used to manage or prevent water flow into specific land regions. Hydropower and pumped-storage hydroelectricity are...
s. The northwestern Atlantic population of this species is strongly migratory
Fish migration
Many types of fish migrate on a regular basis, on time scales ranging from daily to annually or longer, and over distances ranging from a few metres to thousands of kilometres...
: juveniles, followed by adults, arrive off South Carolina
South Carolina
South Carolina is a state in the Deep South of the United States that borders Georgia to the south, North Carolina to the north, and the Atlantic Ocean to the east. Originally part of the Province of Carolina, the Province of South Carolina was one of the 13 colonies that declared independence...
from late March to early May, when the water temperature rises above 20 °C (68 °F). They remain until September to mid-October, at which point the water temperature drops and they move south to Florida
Florida
Florida is a state in the southeastern United States, located on the nation's Atlantic and Gulf coasts. It is bordered to the west by the Gulf of Mexico, to the north by Alabama and Georgia and to the east by the Atlantic Ocean. With a population of 18,801,310 as measured by the 2010 census, it...
. The movements of other populations are unknown.
Description
The body of the finetooth shark is slender and streamlined. The snout is long and pointed, with the nares preceded by short, broadly triangular flaps of skin. The eyes are large and round, with nictitating membraneNictitating membrane
The nictitating membrane is a transparent or translucent third eyelid present in some animals that can be drawn across the eye for protection and to moisten it while maintaining visibility. Some reptiles, birds, and sharks have a full nictitating membrane; in many mammals, there is a small...
s (protective third eyelid
Eyelid
An eyelid is a thin fold of skin that covers and protects an eye. With the exception of the prepuce and the labia minora, it has the thinnest skin of the whole body. The levator palpebrae superioris muscle retracts the eyelid to "open" the eye. This can be either voluntarily or involuntarily...
s). The mouth is broad with well-defined furrows at the corners. There are 12–15 tooth rows on either side of the upper jaw and 13–14 tooth rows on either side of the lower jaw. Each tooth is small and needle-like, with a narrow central cusp and smooth to minutely serrated edges. The five pairs of gill slits are long, measuring about half the length of the dorsal fin
Dorsal fin
A dorsal fin is a fin located on the backs of various unrelated marine and freshwater vertebrates, including most fishes, marine mammals , and the ichthyosaurs...
base.
The first dorsal fin is high and triangular with a pointed apex, originating forward of the free rear tips of the pectoral fins. The second dorsal fin is relatively large and originates over the anal fin. There is no ridge running between the dorsal fins. The pectoral fins are small and falcate (sickle-shaped), with pointed tips. The dermal denticles are small and overlapping, each bearing three horizontal ridges leading to marginal teeth. Living finetooth sharks are a distinctive dark bluish-gray above and white below, with a faint pale stripe on the flanks and no prominent fin markings. Some individuals from Florida have green eyes. Males average 1.6 m (5.2 ft) in length and females 1.7 m (5.4 ft); the largest shark on record was 1.9 m (6.2 ft) long.
Biology and ecology
Both adults and juvenile finetooth sharks form large schoolsShoaling and schooling
In biology, any group of fish that stay together for social reasons are said to be shoaling , and if, in addition, the group is swimming in the same direction in a coordinated manner, they are said to be schooling . In common usage, the terms are sometimes used rather loosely...
. This energetic, fast-moving predator feeds mainly on small bony fishes, often entering the surf zone
Surf zone
As ocean surface waves come closer to shore they break, forming the foamy, bubbly surface we call surf. The region of breaking waves defines the surf zone. After breaking in the surf zone, the waves continue to move in, and they run up onto the sloping front of the beach, forming an uprush of...
during the day to hunt. The most important prey of this species in the northwestern Atlantic is the Atlantic menhaden
Atlantic menhaden
The Atlantic menhaden is a silvery, highly compressed fish in the herring family, Clupeidae. A filter feeder, it lives on plankton caught in midwater. Adult fish can filter up to four gallons of water a minute; and they play an important role in clarifying ocean water...
(Brevoortia tyrannus), with sharks of all ages off northwestern Florida eat almost nothing else. The menhaden are swallowed whole after the head has been removed. Other known prey species include spot croaker
Spot croaker
The spot croaker or spot is a small saltwater fish. The species inhabits estuary and coastal waters along the eastern coast of United States, Gulf of Mexico, and the Caribbean....
(Leiostomus xanthurus), Spanish mackerel (Scomberomorus maculatus), mullet
Mugil
Mugil is one genus among 17 genera containing all together about 80 species of ray-finned fish of the family Mugilidae commonly known as mullet...
(Mugil spp.), shrimp
Shrimp
Shrimp are swimming, decapod crustaceans classified in the infraorder Caridea, found widely around the world in both fresh and salt water. Adult shrimp are filter feeding benthic animals living close to the bottom. They can live in schools and can swim rapidly backwards. Shrimp are an important...
, and in one case a juvenile Atlantic sharpnose shark
Atlantic sharpnose shark
The Atlantic sharpnose shark, Rhizoprionodon terraenovae, is a requiem shark of the family Carcharhinidae, found in the subtropical waters of the northwestern Atlantic Ocean between latitudes 43° N and 25° S,-Habitat:...
(Rhizoprionodon terraenovae), which may have been scavenged
Scavenger
Scavenging is both a carnivorous and herbivorous feeding behavior in which individual scavengers search out dead animal and dead plant biomass on which to feed. The eating of carrion from the same species is referred to as cannibalism. Scavengers play an important role in the ecosystem by...
from the bycatch
Bycatch
The term “bycatch” is usually used for fish caught unintentionally in a fishery while intending to catch other fish. It may however also indicate untargeted catch in other forms of animal harvesting or collecting...
discard of a shrimp trawler. The finetooth shark may be preyed upon by larger sharks.
Life history
Like other requiem sharks, the finetooth shark is viviparous: the developing embryoEmbryo
An embryo is a multicellular diploid eukaryote in its earliest stage of development, from the time of first cell division until birth, hatching, or germination...
s are nourished by yolk for the first 15 weeks, after which the depleted yolk sac
Yolk sac
The yolk sac is a membranous sac attached to an embryo, providing early nourishment in the form of yolk in bony fishes, sharks, reptiles, birds, and primitive mammals...
develops into a placenta
Placenta
The placenta is an organ that connects the developing fetus to the uterine wall to allow nutrient uptake, waste elimination, and gas exchange via the mother's blood supply. "True" placentas are a defining characteristic of eutherian or "placental" mammals, but are also found in some snakes and...
l connection to the mother. Females produce litters of 2–6 pups every other year. In the northwestern Atlantic, mating occurs from early May to early June and the young are born at around the same time the following year after a 12-month gestation period
Gestation period
For mammals the gestation period is the time in which a fetus develops, beginning with fertilization and ending at birth. The duration of this period varies between species.-Duration:...
. The males bite at the female to hold her for copulation. The semen
Semen
Semen is an organic fluid, also known as seminal fluid, that may contain spermatozoa. It is secreted by the gonads and other sexual organs of male or hermaphroditic animals and can fertilize female ova...
exuded by the male congeals into a large spongy mass inside the female's uterus
Uterus
The uterus or womb is a major female hormone-responsive reproductive sex organ of most mammals including humans. One end, the cervix, opens into the vagina, while the other is connected to one or both fallopian tubes, depending on the species...
, in which the individual spermatozoa are embedded. Called a "spermatozeugma", the function of this short-lived structure is unknown. Newborn finetooth sharks measure 48–64 cm (18.9–25.2 in) long. Shallow bays and estuaries, such as Bull's Bay in South Carolina, serve as critical nursery areas for newborns and juveniles.
Female finetooth sharks grow much more slowly and to a larger ultimate size than males. Individuals in the northwestern Atlantic population have a larger body size and reach sexual maturation later than those in the Gulf of Mexico population; males in the two populations grow at similar rates, but northwestern Atlantic females grow more slowly than Gulf of Mexico females. In the northwestern Atlantic, males mature at a fork length (length from snout tip to caudal fin fork) of 99 cm (39 in) and females at 102 cm (40.2 in), corresponding to ages of 5 and 6 years respectively. In the Gulf of Mexico, males mature at a fork length of 94 cm (37 in) and females at 99 cm (39 in), corresponding to ages of 4 and 5 years respectively. The maximum lifespan has been estimated to be at least 9 years for males and 14 years for females.
Human interactions
The finetooth shark has never been implicated in an attack on humans. However, when caught this shark will thrash and snap at anything within range, and people have been bitten attempting to handle it. Finetooth sharks are utilized for human consumption fresh or dried and salted. Other than off the southeastern United States, this species is of little commercial importance: it is small and occurs in water too shallow for most commercial and recreational fisheries, and is generally too fast-swimming to be caught by shrimp trawlers. Small numbers are taken incidentally by floating longlines and on hook-and-line. This species is susceptible to overfishingOverfishing
Overfishing occurs when fishing activities reduce fish stocks below an acceptable level. This can occur in any body of water from a pond to the oceans....
due to its low reproductive rate, and to habitat degradation due to its inshore habits.
Substantial numbers of finetooth sharks are caught in drift gillnet
Gillnet
Gillnetting is a common fishing method used by commercial and artisanal fishermen of all the oceans and in some freshwater and estuary areas. The gillnet also is used by fisheries scientists to monitor fish populations. Because gillnets can be so effective their use is closely monitored and...
s operated by the shark fishery off southeastern United States, which peaked in 1999 at about 117 tons landed. Stock assessments conducted in 2002 suggested that U.S. populations had not yet been overfish
Overfishing
Overfishing occurs when fishing activities reduce fish stocks below an acceptable level. This can occur in any body of water from a pond to the oceans....
ed but that the catch rate was unsustainable, whereas assessments conducted in 2007 concluded that catch rates did not exceed sustainable levels and that populations were stable. Fishing for this species in U.S. waters is regulated by the National Marine Fisheries Service
National Marine Fisheries Service
The National Marine Fisheries Service is a United States federal agency. A division of the National Oceanic and Atmospheric Administration and the Department of Commerce, NMFS is responsible for the stewardship and management of the nation's living marine resources and their habitat within the...
(NMFS) 1993 Fisheries Management Plan (FMP) for Atlantic and Gulf of Mexico sharks; it is classified as a "Small Coastal Shark" (SCS) for the purposes of commercial quotas and recreational bag limits. As a result, the International Union for Conservation of Nature (IUCN) has assessed the finetooth shark as of Least Concern
Least Concern
Least Concern is an IUCN category assigned to extant taxon or lower taxa which have been evaluated but do not qualify for any other category. As such they do not qualify as threatened, Near Threatened, or Conservation Dependent...
overall and off the U.S. and Mexico. There is concern for this species in South America, where its numbers seem naturally low and it is potentially under heavy pressure by widespread, intensive coastal fisheries. However, at present the IUCN does not have sufficient data to assess its status in the region beyond Data Deficient
Data Deficient
Data Deficient is a category applied by the IUCN, other agencies, and individuals to a species when the available information is not sufficient for a proper assessment of conservation status to be made...
.