Rabbit Fish: Chimaera Monstrosa

Family: Chimaeridae

Common name(s)

Rabbit Fish, Rabbitfish, Rat Fish, Rattail.

Identification

A large chimaera with a large bulbous head and tapering body. Snout broadly rounded. Frontal tentaculum (cephalic clasper) present on forehead of males. Eyes very large. mouth wide. Nostrils large, round, and close set.
Pectoral fins very large, triangular, with narrowly rounded apices. Pectoral fin base short, muscular and mobile, supporting thin flexible fins that are used for locomotion. Pelvic fins much smaller than pectorals. First dorsal fin tall and triangular, with prominent rays, and a thick, venomous anterior fin spine that can be raised perpendicularly to deter predators, or lowered when swimming. Curved tip of fin spine exposed; extending above dorsal margin. Second dorsal fin low, straight, and very long, somewhat thinner at mid-length. Anal fin extremely small and inconspicuous, positioned close to caudal. Caudal fins low, long, and rounded. When intact, caudal fin terminates in a very long thin filament; 44-60% of total length.

Colour

Reddish-brown with pale marbling arranged in vague longitudinal stripes. Unmarked snout. Plain brown stripe running from back of head along median (on either side of dorsal fins) to tail. First dorsal and pectoral fins marbled anteriorly. Dorsal and caudal fins mostly translucent bluish grey, fading to black with a thin white band along margin. Caudal filament white. Ventrum white.

Size

Maximum length (including caudal filament) 150cm. Size at birth ~14cm.

Habitat

Temperate and polar seas. Usually benthic on sand and mud, but occasionally seen on rocky reefs. From less than 10m to 1663m but usually 200-700m. Prefers temperatures of 4.7-8ºC.

Distribution

Northeastern Atlantic. Widespread from Greenland to West Africa including the Barents Sea, North Sea, Mid-Atlantic Ridge, and the Mediterranean Sea.

Conservation Status

VULNERABLE

Recent genetic research has confirmed separate stocks of Rabbitfish (Chimaera monstrosa) in the Atlantic Ocean and Mediterranean Sea, with limited migration between the two regions. Some evidence of considerable population declines has been reported across part of its range in the Mediterranean Sea, however, these reports could be an artefact of survey limitations (e.g. not sampling the entire species’ depth range). Rabbitfish are taken as bycatch in deep-water trawl fisheries across its range. Data from the Northeast Atlantic shows official landings for chimaeras have more than doubled from 2006 to 2014, which may be an outcome of increased retention to replace the current zero-total allowable catch (TAC) for deep-water sharks for International Council for the Exploration of the Sea (ICES) member countries. Regional management implementations, including gear restrictions and fisheries closures may offer some refuge from fishing for the species. Given the high spatial overlap with fishing across much of its range, a population reduction of 30–49% is suspected over the last three generations (65 years) based on actual levels of exploitation and documented declines in the Mediterranean Sea, thus meeting Vulnerable A2bd.

Citation

Finucci, B. 2020. Chimaera monstrosa. The IUCN Red List of Threatened Species 2020: e.T63114A124459382. https://dx.doi.org/10.2305/IUCN.UK.2020-2.RLTS.T63114A124459382.en. Downloaded on 07 June 2021.

Reproduction

Oviparous. Egg cases hatch after 9-12 months.
Egg cases are long, thin, and tapered at one end with a feather-like fringe running along most of its length.

Diet

Consumes mostly benthic invertebrates. Will enter shallow water to forage around mussel farms.

Behavior

Swims slowly over the substrate locating food by smell.

Reaction to divers

May bolt if startled, but generally swims slowly away or ignores divers when concentrating on feeding.

Diving logistics

Rarely encountered south of Norway. In Trondheim Fiord, rabbit fish come into water as shallow as 15m at night to forage for food around mussel farms. In this spot, it is not uncommon to see a dozen or more rabbit fish on one dive.