Banner

Fishers For Conservation Fish Focus Page: The Elephant Fish elephant fish 06/07/2006

Species common Name(s): Elephant Fish, Elephant Shark, Ghost shark, Reperepe (Maori), Southern Beauty

Species Scientific name: Callorhinchus milii

Family: Callorhinchidae (Plownose chimaeras) Order: Chimaeriformes (chimaeras) Class: Holocephali (chimaeras) note - Four closely related species are now recognised, requiring further revision of this class.

Size

Up to 1.5 metres (sources vary) Usually caught between 50 and 125 cm TL

Conservation Status

Very little is known about the conservation status of this species, though this does not deter major commercial catches being taken in both Australian and New Zealand waters.
Like most shark species the Elephant shark is slow growing and takes a long time to reach maturity. These characteristics along with its limited range make this species vulnerable to intensive fishing.

Modern commercial fishing methods such as demersal trawling are able to catch huge numbers of these fish while damaging critical benthic (sea floor) habitat and leaving a wake of dead and dying ‘bycatch’ (unwanted species thrown back into the ocean).
An interesting thought is that Elephant fish may thrive in the cleared underwater deserts created by the supertrawlers, if they can escape the nets in sufficient numbers to maintain their population.

Distribution/Environment

The Elephant fish inhabits subtropical (33°S - 50°S) continental shelf waters of the Southwest Pacific adjoining Southern Australia and New Zealand. Living to depths of at least 200m this fish is associated with muddy or soft bottoms.

Description

A silvery coloured fish with beautiful iridescent reflections and dark, variable markings on the side. On its snout it has a fleshy hoe shaped structure used in conjunction with obvious sensory canals and pores on the head, in foraging for food in the muddy bottoms of deep water. Its two dorsal fins are high and triangular, with an elongated upper lobe on the tail with a short lower lobe immediately preceded by a pointed anal fin, appearing to be part of the tail. The Pectoral fins are large and in front of its first dorsal fin it has a large serrated spine, which is thought to be poisonous. The Elephant shark has only a single paired gill opening and smooth skin (unlike most non-Chimaerid sharks).

Biology

Elephant fish are benthic (bottom dwelling) fish feeding in sandy or muddy areas usually in deeper continental shelf waters.

In spring, adults migrate into coastal bays and estuaries to lay their egg cases on the sandy or muddy bottom. Large eggs are contained in a yellow-brown horny capsule measuring up to about 25x10 cm. In the centre of the egg case is a cavity in which the embryo develops. From one end of this cavity a passage, closed by a special valve, leads to the exterior, and it is through this passage that the young fish in due course, escapes. Eggs take up to eight months to hatch and Elephant Fish are slow in growing, taking about 5 years to reach maturity. The distinctively shaped egg cases are sometimes found washed ashore after storms.

 

Recreational and/or commercial catch data

Catch data for this species is difficult to come by in Australia. Various sources refer to commercial catches in the 100’s of tonnes in both Australia and New Zealand and little seems to be known about the population or ecosystem effects of this fishery. In 2000 over 30 tonnes were sold through the Melbourne fish market alone. Surprisingly prices for this acknowledged good eating fish were only a quarter of that recorded for other commercial shark species.

In New Zealand fisheries have recently consistently exceeded the total allowable catch (TOC - 1069 tonnes p.a.) for this species, as they are unavoidable bycatch in the demersal trawl fishery. It is considered that this species is recovering form severe overfishing in the mid 80’s but the Ministry of Fisheries acknowledges that it had insufficient data to assess the appropriateness of its TOC level.
The Australian Fisheries Management Authority does not consider this species a ‘priority species’ and it is seemingly excluded from all research efforts.

Recreational fishing survey data fails to record this species specifically instead referring to data for ‘sharks and rays’. Anecdotal evidence suggests this fish is rarely targeted by recreational fishers and catch levels are not significant (with the possible exception of seasonal effort in Port Phillip Bay)

. Elephant Shark can caught from the shore at night in some areas.

Fishing regulations – Legal size, bag limit etc.

The lack of knowledge regarding the status of this species is reflected in a lack of fishing regulations regarding this fish.  Victorian regulations are the only ones to recognise the Elephant Fish in its own right with a bag limit of 3 per person.
Various Australian states have bag limits relating to shark species in general though it is unclear if these apply to Elephant Fish, as they are not part of the Class Chondrichthyes referred to in regulations.

The FFC recommends that a legal size limit of 60cm be provisionally introduced in the absence of detailed data; we acknowledge that the majority of fish currently taken exceed this proposed size limit.

What you can do to conserve this species and its habitat

The single most important thing you can do to help conserve this species is to oppose the use of the most damaging fishing method – demersal trawl (beam and otter trawl). This form of fishing is indiscriminate leading to large amounts of bycatch (wasted fish and other species discarded, generally dead) and is extremely damaging to marine habitats. The effects of this fishing gear can be likened to clear felling in terrestrial forests where chains strung between tractors drag the landscape bare destroying all in their path.

When fishing for Elephant Fish use of circle hooks will reduce the incidence of deep hooking and increase survival of released fish. All the normal precautions and practices should be adhered to when catching and handling this species. See The National Code of Practice for Recreational and Sport Fishing and the Code of Practice on Releasing Fish for general information.

Chimaerids

Elephant fish are Chimaerids. “Chimaerids are closely related to sharks, having a similar cartilaginous skeleton but lacking the flattened body form of skates and rays. Representatives of this order are found in all the oceans of the world, but they are generally restricted to cool temperate regions in waters between 200 and 1200m depth. They can be distinguished from sharks by their gill slits being covered with a skin (operculum), leaving a single opening on each side. Chimaerids also have smooth skins without the dermal denticles of sharks. They also have a single spine in front of their first dorsal fins, which can be laid flat as in bony fishes. Their heads are grooved with lateral lines and their upper jaws are fully fused to their heads, unlike in sharks where the upper jaw is only loosely attached to the skull. Their teeth are modified to form flattened crushing plates with sharp cutting margins (two pair in the upper jaw, and a single pair in the lower jaw).
Male Chimaerids have the normal claspers or intromittent sexual organs that are present in the sharks and rays alongside their pelvic fins, but they also have a second pair of flat, retractable claspers in front of the pelvic fins. These are usually armed with hooks and are probably used only to grip the female during mating. There is also a club-like frontal clasper on top of the head. All chimaerids are oviparous, laying large eggs in a horny case which is deposited on the bottom. Like most sharks and rays, development is slow and the young do not hatch until six months to a year after the eggs are laid.
Chimaerids live mainly on soft muddy bottoms on the deeper parts of the continental shelf or on the continental slope. They feed mainly on shellfish and bottom-living invertebrates, as well as a few small fish.” (seafriends.org.nz)

References / further information

Web references

http://www.marinethemes.com/elephant.html

fishbase.org - http://filaman.ifm-geomar.de/Summary/SpeciesSummary.php?id=4722

Australian Museum Fish Site - http://www.amonline.net.au/fishes/fishfacts/fish/cmilii.htm

Sea friends - http://www.seafriends.org.nz/enviro/fish/sharkray/chimaeri.htm

Australian Fisheries Management Authority - http://www.afma.gov.au/research/reports/2002/r02_0930.pdf

NZ ministry of fisheries homepage - http://services.fish.govt.nz/fishresourcespublic/Plenary2005/ELE_05.pdf

Other Refs

Kuiter, R.H. (2000) Coastal Fishes of South Eastern Australia. Gary Allen Pty Ltd, Sydney.  pp24

Gommon, M.F., Glover, J.C.M. and Kuiter, R.H. (1994) The Fishes of Australia’s South Coast. State Print, Adelaide. pp190-191