The Gulper shark (Centrophorus granulosus) is a long and slender dogfish, belonging to the family Centrophoridae. They are medium sized with smoother skin, distinct green eyes and two dorsal spines. Gulper sharks are widespread and can be found in deep water. Their reproduction rates are as slow as humans. In some locations their populations have depleted by 80%.
Family: Centrophoridae – Gulper Sharks
Genus: Centrophorus
Species: granulosus
Phylum– Chordata
Class– Chondrichthyles
Subclass– Elasmobranchii
Common Name– Dogfish Sharks
Family– Centrophoridae
Common Name– Gulpher Sharks
Genus– Centrophorus
Species– granulosus
Status: IUCN Red List VULNERABLE
Average Size and Length: Gulper sharks are born 11.8-16.6 inches. The size of an average adult male is 2-2.6 feet. The size of an average adult female is over 3 feet long. The maximum length is 3.5-4.9 feet long.
Teeth and Jaw: The teeth of the Gulper shark belonging to both jaws are “blade-like” and form interconnecting cutting edges. The teeth of the upper jaw are moderately broad with cusps varying from upright to oblique. The teeth of the lower jaw are broader than that of those on the upper jaw and they have an oblique asymmetrical cusp. The number of tooth rows vary from 33-40 tooth rows on the upper jaw to 30 rows on the low jaw. The upper teeth and the bottom teeth are finely serrated.
Head: The Gulper shark has a short, thick snout. The anterior nasal flaps are short. The eyes are green in color.
Denticles: The skin of a Gulper shark is smooth to the touch. They have wide-spaced, block-shaped dermal denticles that do not overlap and do not have pedicels.
Tail: There is a shallow notch in the postventral caudal fin margin in adult Gulper sharks. The lower lobe is somewhat long. The upper lobe of the caudal fin is moderately long and developed.
Demographic, Distribution, Habitat, Environment and Range: Gulper sharks are widespread. They can be found in the Atlantic, the western Indian Ocean, and the west Pacific and possibly the central Pacific. They can be found over continental shelves and slopes on or near the bottom. The Gulper shark is a bathydemersal. They can be found anywhere between 165-4,725 feet, but typically stay between 655-1,970 feet. Some research suggests that the juveniles occupy the lower depths more than the adults. They prefer tropical to temperate waters. Some suggest that they prefer murky water, but this is unconfirmed.
Diet: Gulper sharks mainly eat bony fish, crustaceans and squid. Research suggests they could eat lanternfish.
Larger fish, sharks and marine mammals could possibly pray on Gulper sharks, but this is unconfirmed.
Aesthetic Identification: Gulper sharks are slim and somewhat long. They are dark grey to grey brown above and lighter underneath. Their fin webs are dusky and the tips are darker in juveniles. The free rear tips of the pectoral fins extend into an acute lobe. The first dorsal fin is short and high. The second dorsal fin is almost as high as the first, with the spine base over the inner pelvic fin margins. The dorsal fin spines are grooved. There is no anal fin.
Biology and Reproduction: Gulper sharks reach maturity between 12 to 16 years for females, and between 7 to 8 years for males. Male Gulper sharks typically outnumber females 2:1. The life expectancy of female Gulper sharks ranges between 54 and 70 years. Having a long, life expectancy but a low net reproduction rate suggests that the population of Gulper sharks would be at a very high risk if too many of them were killed from excessive fishing.
Gulper sharks are ovoviviparous and participate in oophagy. Female gulper sharks typically have between 2 and 10 pups in their lifetime, with generally 1-2 pups per litter, this is considered to be a low fecundity. Gulper sharks have a long gestation period, around two years. Gulper sharks can have long resting periods between pregnancies.
Behavioral Traits, Sensing and Intelligence: Research suggests that they migrate and appear to school or shoal in small groups.
Gulper Shark Future and Conservation: Gulper sharks are considered vulnerable. They are targeted and also a bycatch of deepwater fisheries for their meat and liver oil. They take a long time to reproduce. Human interaction with the Gulper shark exists mainly in the form of fishing. Longline fishing is a typical method for fishing at the depth required to catch Gulper sharks. This is common practice to catch them globally. There have been significant population drops, in some areas as significant as 80%. They are very susceptible to overexploitation.
The General Fisheries Commission for the Mediterranean (GFCM), which is in charge of almost all intergovernmental fishery management decisions, mandated in 2005 to stop expanding deep water fishing beyond 1,000 meters. This mandate however, does not support the main population of Gulper sharks, which generally live 300–800 meters below the surface. Current deepwater fishing was not impacted, and therefore this conservation effort is ineffective. There are no other conservation efforts in any other area specific to this species. However, so other mandates do have a positive impact on the Gulper shark conservation efforts.
There are tagging efforts in place to monitor Gulper sharks, which is a good current population monitoring system, however a very passive conservation effort to no conservation effort. It is a way for us to gather population data. In addition, there is no collective central shared data location, and thus a lot of the data is rendered useless and outdated by the time anyone finds it.
Gulper Shark Recorded Attacks on Humans: Not a threat to humans.