Rasptooth Dogfish

About the Rasptooth Dogfish

The rasptooth dogfish is a a shark species found south of Japan, at depths of about 360 m (1,181 ft). Very little is known about their biology or their behaviour as only a few specimens have been studied. They’re presumed to be ovoviviparous, meaning it produces young by means of eggs that hatch inside the mother’s body, but litter sizes are unknown. They reach lengths of 43 cm (16.9 in).

There is some controversy regarding this shark’s family tree. They have been placed in the dogfish family, but more recent DNA tests puts them in the lanternshark family. They have also been placed in their own genus are known as miroscyllium shekoi, by Fishbase and IUCN.

It is taken by demersal trawl fisheries and retained for fish meal. The small size of the species may reduce its catchability. The deep-water trawl fishery in Taiwan has moved deeper over the past 30 years from 100–300 m (328–984 ft) to 300–700 m (984–2,297 ft) deep. During the monsoon season, the conditions preclude deep-water trawling and some trawlers operate in the shallower depths of 100–300 m (328–984 ft). In Japan, bottom trawl fishing effort decreased markedly over the last three decades and is continuing to decline. It has never been commonly seen at landing sites with little change in the observed abundance since the species was first described in 1986. This infers a stable population as fishing effort has remained relatively stable. The ban on trawls in Taiwan within 3 nautical miles and the fewer deep-water trawls in the monsoon may provide some refuge. The species may have refuge from fishing pressure if it occurs to 1,000 m (3,281 ft), and it may be naturally uncommon. There is no evidence of population decline and since the Rasptooth Dogfish is not suspected to be close to reaching the population reduction threshold, it is assessed as Least Concern. This species is too small for human consumption and is used for fish meal in Taiwan, and possibly discarded in Japan (D. Ebert unpubl. data 2019).

No specific measures are in place. Since 1999, all demersal trawling in Taiwan is prohibited within 3 nautical miles (nm) of the coast and within 12 nm for trawlers larger than 50 Gross Registered Tonnage (Fisheries Agency 2019, Liao et al. 2019). In Japan, management measures have been implemented since the mid-1990s to control fishing effort that include total allowable catches, seasonal closures, and gear restrictions (White Paper 2015). Research is needed on population size and trend, and life history, and catch rates should be monitored.

 

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