Once fertilized, females can hold up to 6 mature egg cells, or oocytes, in their body at a time. The length of time these egg cells are kept inside the female's body is called the gestation period. Gulper sharks have a long gestation period, around two years. Gulper sharks can have long resting periods between pregnancies. They are ovoviviparous, meaning the only parental care they give their young is during the incubation period. Since not all oocytes form into pups, when a pup or two is formed inside the female, they eat the remaining fertilized eggs, known as oophagy. After they are born, they are on their own. Having a low fecundity, a long gestation period, breaks between pregnancies, and a late age of maturity all contribute to the gulper shark having a very low net reproduction rate. It is believed that the gulper shark has the lowest reproduction rate of any elasmobranch species. Geographic range The gulper shark is a deepwater oceanic species, living in waters ranging between 100 and 1490 meters in depth, with the juveniles being the main occupant of the lower half of the depths. Acceptable habitats for gulper populations are found globally, wherever temperate and tropical waters are found. The gulper shark is most commonly found in the 300 to 800 meter depth range, inhabiting the upper continental slopes and outer continental shelves, the gulper is highly migratory species and has schooling habits based on multiple sharks being present around baited cameras. Due to the frequency and patterns of migration the gulper shark population estimates may be inaccurate with some sharks being counted twice, which are exacerbated by inappropriate tagging techniques. There are multiple species of gulper sharks, which has contributed to misidentification in the past. For example, populations of the gulper shark in the Southeast Atlantic Ocean may represent a separate species. Therefore, taxonomic confusion may influence current geographical range. The gulper sharks like deep, murky waters. Human interaction Fishing and bycatch 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, and the broad distribution of gulper habitat leads to this method being used to catch gulpers around the world. However, gulper sharks are not always caught intentionally. The deep waters in which the gulper and similar shark species live is difficult to harvest,