Today we look at the Blackmouth Dogfish in the tenth of our Species Fishing and ID guides.
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Other Names: Galeus melastomus, Blackmouth Catshark
Description: Blackmouth’s are a slender dogfish with a distinct marbled brown dorsal surface. The inside of the mouth is black in colour, giving the fish its name. Blackmouth Dogfish have two small, rounder dorsal fins and long, almost continuous ventral fins. The tail of the dogfish is long and compressed with a very small lobe.
Maximum Size: 80cm
Habitat: Blackmouth Dogfish are found over a wide range of sea beds but generally in deep water areas, as such Blackmouth’s are generally caught over muddy sea beds.
Depth: 55-3,850m, juveniles are often found in shallower waters than adults but are very rarely found in waters less than 50m deep.
Distribution: Generally found offshore around the Scottish coast or close to shore in deep water areas.
Feeding: Blackmouth Dogfish are opportunistic predators and scavengers; they feed mainly on small crustaceans, squid and fish.
Biology: Males mature at 48-79cm and females at 56-79cm, age at maturity is unknown. Blackmouth Dogfish are oviparous (egg-laying); females lay up to 13 eggs after mating. Mating and egg laying is found to occur all year round but the frequency of reproduction is not know, it is estimated that mature females may lay 60-100 eggs per year. Blackmouth Dogfish egg cases are deposited on muddy sea beds in relatively shallow waters, the eggs are around 3.5-6.5cm in length and vase shaped (tapering at both ends) with very small horns.
Caution: Relatviely harmless though they do have rough skin and small, sharp teeth.
Current Fishery: Blackmouth Dogfish are generally not targeted commercially due to their low economic value though are occasionally taken as bycatch in deep water fisheries for human consumption.
Conservation Status: Least concern. However relatively little is known about this deep-water shark.
GFAC Size: The release of Blackmouth Dogfish is recommended by the SSTP.
Tagging: Blackmouth Dogfish are not currently tagged under the SSTP, however capture of Blackmouth’s should be reported to the SSTP in the same way as undersized fish.
Targeting Blackmouth Dogfish in Scotland
Tackle: Although Blackmouth Dogfish are generally small they are often found in very deep water, this means that weather and tide conditions rather than the fish itself are likely to influence tackle selection. In general a 6-12lb class boat rod is suitable.
End Tackle: Small shrimp rigs or flapper rigs with barbless size 4 hooks are suitable for Blackmouth Dogfish. The fish are generally small and will pick up small baits.
Bait: Popular baits include small strips or squares of mackerel, sandeel and squid.
Tactics: Blackmouth Dogfish are generally found in deep water, using braid eliminates line stretch and will show bites clearly even in water over 200m deep.