A large angelshark species with a head inline with the pectoral fin margins. Thin, unfringed, cylindrical barbells with slightly spatulate tips. Nasal flaps weakly fringed or smooth. Spiracle to eye distance about 1.5x eye size. Concave forehead between eyes. Rows of small thorns (enlarged denticles) present on snout, between eyes and spiracles, and along midline of back. Pectoral fins have somewhat rounded apexes.
Dorsal coloration cream or tan with a dense covering of irregular, reddish-brown spots. Spots on either side of midline coalesce to form large, paired irregular blotches. No ocelli on pectoral fins. Ventrum pale. Dorsal and caudal fins pale and unmarked except near their bases.
Maximum size possibly 150cm. Reports of 2m individuals unsubstantiated. Size at birth approximately 22cm.
Temperate sandy substrates often close to monumentation such as rocky reefs. Inshore and continental shelf. From around 15m (personal observation) to at least 300m.
Northwest Pacific / Sea of Japan. Found from Korea, Japan, China, and Taiwan.
This species is apparently taken in large numbers in demersal trawl fisheries and is also likely caught as bycatch in set net and gillnet fisheries throughout large areas of its distribution (Compagno in prep.). It is unknown whether this species is truly targeted by fishing operations, but it is retained and can been found in local fish markets in Taiwan Island and Japan (S. Tanaka and D. Ebert pers.obs. 2007).
The East China Sea and Yellow Seas are intensively exploited, with several stocks declining due to overfishing and pollution (NOAA 2004ab). Heavy fishing mortality has resulted in a shift from an older, traditional fishery based on high-value demersal species to faster-growing, smaller, and lower-value species such as shrimp and cephalopods (NOAA 2004a). The Yellow Sea was once one of the most intensively exploited Large Marine Ecosystems (LME) in the world and is considered severely impacted in terms of overfishing, with destructive fishing practices (NOAA 2004b).
Fishing pressure from trawl vessels is intense off China, despite bans on bottom trawling in various areas. China has the largest number of fishing vessels and fishers in the world with a marine fishing fleet consisting of 279,937 motorized vessels in 2004 (1,996 of which were confined to distant waters), showing little change from 1999 (FAO 2007b). Catches have declined as a result, leading to catches of immature, small-sized and low value organisms (FAO 2007b). In 2004, the most common fishing gear used was the trawl net (in terms of production, trawlers accounted for 47.6% of catches in 2004 (FAO 2007b). Progress is being made in the introduction of ecosystem based management in the Yellow Sea and a fisheries recovery plan requires the cooperative effort of all countries bordering it. The Yellow Sea LME Project will assess fish stocks and establish TACs (NOAA 2004b). In February 2006, the Government of China issued the Programme of Action on Conservation of Living Aquatic Resources of China. This states that by 2010 they aim to reduce the size and power of the motorized marine fishing fleet and the corresponding domestic marine capture catch in China from 220,000 vessels with a total power of 12.7 million kW and catching 13.06 million tonnes marine organisms in 2002, to 192,000 vessels, 11.43 million kW (FAO 2007b). This represents a decline in fishing power of only 10%.
Other angel shark populations (e.g., Squatina californica, S. squatina, S. argentina) have proved particularly vulnerable to fishing pressure due to their low reproductive potential, vulnerability to trawl and gillnet fishing gear and low potential for recolonisation (due to their sedentary habit) (Gaida 1997, ICES 2004, Morey et al. 2006, Vooren and Klippel 2005). Squatina guggenheim and Squatina occulta, which occur in the Southwest Atlantic Ocean, have a triennial reproductive cycle, with a litter size of only two to eight pups. This extended breeding cycle means that they have a very low intrinsic rate of population growth. Consequently, these sharks are generally highly vulnerable to extirpation through bycatch in fisheries that are managed to sustain production of other, more productive, fishes (Musick et al. 2000, C. Vooren pers. comm. 2007).
Walsh, J.H. & Ebert, D.A. 2009. Squatina japonica. The IUCN Red List of Threatened Species 2009: e.T161558A5451036. https://dx.doi.org/10.2305/IUCN.UK.2009-2.RLTS.T161558A5451036.en. Downloaded on 24 January 2021.
The angular angelshark is an aplacental viviparous species. 2-10 pups per litter.
Feed on demersal fishes, molluscs and crustaceans.
Angel sharks are ambush predators that lay on the substrate partially covered by sand. When a fish swims within range, the angelshark explodes upwards from its concealment, mouth agape and clamps down on its prey.
Japanese angelsharks migrate into shallow bays along the Izu Peninsula during the winter months.
Reaction to divers
Easy to approach. Remains motionless, relying on camouflage. Will bolt if molested.
The Japanese angelshark is quite common at a few spots along the Izu Peninsula during the coldest winter months.
One excellent location is Izu Ocean Park; a shore diving spot with a sandy slope that starts at around 15m and quickly drops to below recreational diving depths. IOP often gets quite busy with local divers (especially at the weekend) causing the sharks to retreat into deeper water.
More difficult to reach (and therefore less busy) is Hatsushima Island off the east coast of Izu. This is another excellent shore diving site where numerous Japanese angelsharks can usually be found.
Mikomoto Island on the southeast tip of Izu is another area where angelsharks are regularly seen but sightings are not as frequent as IOP or Hatsushima.
There are also reports of winter sightings from the south coast of Chiba Prefecture.
The best way to search for angelsharks is to swim along the edge of the reef, about 2m above the sand, in rocky or kelpy areas where the sharks have sand they can hide under and access to a good supply of fishes.
Although the shark will likely be buried under a fine covering of sand, their outline is often somewhat visible. Even if the outline of the angelshark is obscured, they always keep their eyes and spiracles exposed. After a few encounters, you should be able to pick out the signs of a shark’s presence more easily.
Once you have located a shark, with slow, non-aggressive movements, it is usually possible to settle down next to it and gently fan away most of the sand to get a better look. This does not distress the animal or significantly waste its energy because one or two pectoral fin flaps will completely cover it again. Be careful not to wave your hand too close to its mouth to avoid a demonstration of its incredibly fast bite reflex!