What the Japanese Sawshark Is and Where It Lives
The Japanese sawshark is a small, flattened shark found in deep waters off Japan and nearby parts of the western Pacific. It is not a target species for recreational fishing — most anglers will never encounter one, and it is illegal to keep in most jurisdictions where it occurs. The fish is notable for its flat body shape and a long, flat snout edged with tooth-like projections that resemble a saw, which gives the species its name.
This shark lives at depths between 200 and 1,600 feet, well below the range of most recreational saltwater fishing. It prefers continental shelf and slope habitats where the seafloor is soft mud or sand. The species is found primarily around Japan, the Philippines, and parts of the South China Sea, making it geographically remote from most North American fishing grounds.
Japanese sawsharks are small — adults typically reach only 3 to 4 feet in length. They are ovoviviparous, meaning females carry eggs internally and give birth to live young. The species feeds on small fish and crustaceans on or near the seafloor, using its saw-like snout to probe and dig through sediment.
Key Takeaways
- Japanese sawsharks live in deep water (200 to 1,600 feet) off Japan and the western Pacific, far beyond recreational fishing depth.
- The species is protected in most regions where it occurs and cannot legally be retained by recreational anglers.
- These sharks are small (3 to 4 feet) and feed on the seafloor, making them of no commercial or sport value.
- Accidental capture by commercial deep-sea fishing operations is rare and typically results in the fish being released or discarded.
Depth and Habitat Requirements
The Japanese sawshark occupies a narrow ecological niche in deep, cold water where light does not penetrate. It is found most commonly between 600 and 1,200 feet, though specimens have been recorded as shallow as 200 feet and as deep as 1,600 feet. This depth range places it well outside the reach of standard recreational fishing methods, including bottom fishing, trolling, and jigging from boats.
The seafloor habitat is critical to the species' survival. Japanese sawsharks prefer soft substrates — mud, sand, and silt — where they can use their saw-like snout to search for prey. Hard rocky bottoms and coral reefs are not suitable habitat. The water temperature in these depths remains cold year-round, typically between 35 and 50 degrees Fahrenheit, which is consistent with the species' metabolic needs.
Because of these strict habitat requirements, the Japanese sawshark has a limited range and does not migrate seasonally. Populations remain localized to specific continental shelf and slope regions where depth and substrate conditions align with the species' needs.
Why You Won't Encounter One While Fishing
Recreational saltwater fishing in the western Pacific — even in Japanese waters — does not typically reach the depths where Japanese sawsharks live. Most recreational boats fish between the surface and 300 feet, and the vast majority of angling activity occurs in shallower water still. Specialized deep-sea fishing charters exist, but they target larger, more commercially valuable species like deep-sea snappers and groupers, not small sawsharks.
Commercial fishing operations that do work at these depths — primarily bottom trawlers and longliners — occasionally capture Japanese sawsharks as bycatch. When this occurs, the sharks are typically dead or dying by the time they are brought aboard, as the pressure change from deep water to the surface is fatal to many deep-sea species. Most commercial fisheries in the region have protocols to document and release bycatch, though survival rates are low.
Even if you were fishing in Japanese waters with deep-sea equipment, the likelihood of hooking a sawshark is extremely low. The species is not abundant, and it does not respond to standard baits or lures used in recreational fishing. Its small size and bottom-feeding behavior make it an incidental catch at best.
Legal Status and Conservation
The Japanese sawshark is not currently listed as endangered by international conservation bodies, but it is protected under Japanese fisheries law and cannot be retained by recreational anglers. Some regional fisheries management organizations have catch restrictions or bycatch reporting requirements for sawshark species, though enforcement varies.
The species' population status is not well documented, as deep-sea research in the western Pacific is limited and ongoing. Commercial bycatch data suggest the species is not abundant, but whether populations are stable, declining, or recovering is unclear. The International Union for Conservation of Nature (IUCN) has not formally assessed the Japanese sawshark, meaning no official conservation status has been assigned.
If you somehow catch a Japanese sawshark — whether through deep-sea fishing or as a bycatch observer on a commercial vessel — the correct action is to release it immediately if it is still alive, or to report the capture to local fisheries authorities if it is dead. Do not attempt to keep it as a specimen or trophy.
Sawshark Biology and Behavior
The Japanese sawshark's most distinctive feature is its rostral saw — the elongated, flattened snout edged with tooth-like projections. This structure is not a true saw in the mechanical sense; rather, it is a sensory and feeding organ. The saw is covered with electroreceptive organs called ampullae of Lorenzini, which allow the shark to detect electrical fields generated by prey animals hiding in the seafloor sediment.
The shark uses its saw to probe, dig, and slash through mud and sand, disturbing prey and bringing them into range of its mouth. Small fish, shrimp, and other crustaceans make up the bulk of its diet. The saw also serves a defensive function, though predators of adult sawsharks are not well documented.
Japanese sawsharks are ovoviviparous, with females giving birth to litters of 4 to 7 pups per year. Gestation period and age at maturity are not precisely known, but based on the species' small size and deep-water habitat, sexual maturity likely occurs at 2 to 3 years of age. Lifespan is estimated at 15 to 20 years, though this is speculative.
Sawshark Species and Confusion with Sawfish
Sawsharks and sawfish are often confused because both have saw-like rostrums. The key difference is taxonomic: sawsharks are sharks (class Chondrichthyes, subclass Elasmobranchii), while sawfish are rays (also class Chondrichthyes, but a different subclass). In practical terms, sawfish have gill slits on the underside of their body, while sawsharks have gill slits on the sides of their head, like other sharks.
The Japanese sawshark is one of about 20 sawshark species found worldwide, most in deep water. Other sawshark species occur in the Atlantic, Indian Ocean, and other parts of the Pacific. None are common in recreational fishing, and most are protected or restricted by regional fisheries regulations.
Sawfish, by contrast, are critically endangered and fully protected in most countries. If you encounter any sawfish species, it must be released immediately and reported to fisheries authorities. Sawfish are larger than sawsharks and occur in shallower water, making them more likely to be encountered by recreational anglers in tropical and subtropical regions.
Frequently Asked Questions
Can I keep a Japanese sawshark if I catch one?
No. The species is protected under Japanese fisheries law and cannot be retained by recreational anglers. If you catch one, release it immediately if it is alive, or report the capture to local fisheries authorities if it is dead. Keeping a protected species can result in fines and legal penalties.
What is the difference between a sawshark and a sawfish?
Sawsharks are sharks with gill slits on the sides of their head; sawfish are rays with gill slits on the underside of their body. Sawfish are larger, occur in shallower water, and are critically endangered. Both have saw-like rostrums, but they are not closely related.
Where would I need to fish to have a chance of catching a Japanese sawshark?
You would need to fish in deep water (600 to 1,200 feet) off Japan or nearby parts of the western Pacific using specialized deep-sea equipment. Even then, the chance of encountering a sawshark is extremely low. Most recreational fishing does not reach these depths, and commercial deep-sea operations do not target sawsharks.
Are Japanese sawsharks dangerous to humans?
No. The species is small (3 to 4 feet), lives in deep water far from human activity, and has no documented history of attacking people. There is no risk of encountering one while swimming or recreational diving.
Is the Japanese sawshark endangered?
The species is not formally listed as endangered, but its population status is poorly understood. Deep-sea research in the western Pacific is limited, and bycatch data are incomplete. The International Union for Conservation of Nature has not conducted a formal assessment.