Habitat and Ecology
Usually produces 12 pups per litter (Compagno in prep.). It grows to a maximum total length of 136-153 cm, with males maturing at 80-100 cm and females maturing at approximately 100 cm (Compagno in prep.). Size at birth is approximately 30 cm TL (Yamada et al. 2007). Feeds on small bottom dwelling organisms (Compagno in prep).
The species may make vertical migrations, according to water temperature, from shallow coastal waters to the upper continental slope (S. Tanaka pers. obs. 2007). The species can only be collected in coastal waters of the Izu Peninsula, Shizuoka, in early spring when water temperature is at its lowest (S. Tanaka pers. obs. 2007).
Life History and Behavior
IUCN Red List Assessment
Red List Category
Red List Criteria
This species is captured as a utilised bycatch of gill nets, trawl nets and bottom longline fisheries. This is not a commercial species, but it is particularly susceptible to capture in gillnets because of the thorns on the snout (Yamada et al. 2007). This species is captured as bycatch in gillnet fisheries targeting spiny lobster set in less than 20 m depth. Although the fishery operates from September-April, the species only occurs as bycatch during March-April. It is thought that the species moves into deeper waters throughout the rest of the year. It is captured occasionally at depth of 200-400 m by trawl net fisheries in the East China Sea (Yamada et al. 2007). It is also an uncommon catch of trawl net fisheries operating in Suruga Bay, Japan (S. Tanaka pers. obs. 2007).
According to the Law of Fisheries of China, bottom trawling is banned within certain areas of Chinese waters (Y. Wang pers. comm. 2007). Bottom trawling is restricted in certain zones and at different times in shallow water (Y. Wang pers. comm. 2007). Individual Provinces must apply national regulation within China. They also apply their own regulations on the basis of national regulations (Y. Wang pers. comm. 2007).
Relevance to Humans and Ecosystems
The Japanese sawshark (Pristiophorus japonicus) is a species of sawshark in the family Pristiophoridae. This shark has a long, narrow rostrum. Its first dorsal fin originates behind the tips of the pectoral fins, and its caudal fin is angled almost straight in line with the body. The Japanese sawshark reaches an maximum length of up to 1.36 m (4 ft 6 in).
Range and Habitat
Found in the northwest Pacific Ocean around Japan, Korea, and northern China between latitudes 48°N and 22°N. It is found over the sandy or muddy bottoms of the continental shelf at depths of 50 to 800 m (160 to 2,620 ft). This species may vertically migrate in the water column because of changes in temperature.
The Japanese sawshark has a varied diet of small benthic organisms. Like seemingly all sawsharks, this species is ovoviviparous. After an unknown gestation period, the female shark gives live birth to around 12 pups. These pups average around 30 cm (12 in) long. At sexual maturity the male is 80 to 100 cm (31 to 39 in) long, and the female is around 100 cm (39 in) long.
With little information on population size or frequency of bycatch, the Japanese sawshark is listed by the IUCN Red List as being Data Deficient. It is not clear if this shark's apparent rarity is because of natural reasons, or because the population has already been depleted. Due to its benthic lifestyle, and because the range of this shark is heavily fished, it is safe to assume that the Japanese sawshark is at considerable risk of being caught as bycatch in bottom trawling and gillnet operations. Because of its habitat and behavior, this shark poses no threat to humans.