The sea sweep (''Scorpis aequipinnis''), also known as the maomao, snapjack, or sweep is a

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

of marine

ray-finned fish Actinopterygii (; ), members of which are known as ray-finned fish or actinopterygians, is a class of bony fish that comprise over 50% of living vertebrate species. They are so called because of their lightly built fins made of webbings of sk ...

from the

subfamily In biological classification, a subfamily (Latin: ', plural ') is an auxiliary (intermediate) taxonomic rank, next below family but more inclusive than genus. Standard nomenclature rules end botanical subfamily names with "-oideae", and zo ...

Scorpidinae The Scorpidinae, commonly known as halfmoons, knifefishes, and sweeps, are a subfamily of the family Kyphosidae, the sea chubs, a family of marine fish in the order Perciformes. The Scorpidinae are distributed throughout the Pacific and east In ...

of the

sea chub The sea chubs, also known as rudderfish and pilot fish and in Hawaiian as ''enenue'' or ''nenue'', are a family, Kyphosidae, (from Greek, ''kyphos'' = hump) of fishes in the order Perciformes native to the Atlantic, Indian and Pacific Oceans u ...

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

Kyphosidae. It is native to the southwestern

Pacific Ocean The Pacific Ocean is the largest and deepest of Earth's five Borders of the oceans, oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean, or, depending on the definition, to Antarctica in the south, and is ...

from Australia to New Zealand.

Description

The sea sweep has deep and strongly compressed body with a thin caudal peduncle. The head is moderately sized with an almost straight dorsal profile, a short snout and quite large eyes. The mouth is small and oblique with small but strong teeth in the jaws arranged in broad bands with the outer band being enlarged and recurved. Most of the body is covered in very small ctenoid scales and there is a gently curved

lateral line The lateral line, also called the lateral line organ (LLO), is a system of sensory organs found in fish, used to detect movement, vibration, and pressure gradients in the surrounding water. The sensory ability is achieved via modified epithelia ...

. The

dorsal fin A dorsal fin is a fin on the back of most marine and freshwater vertebrates. Dorsal fins have evolved independently several times through convergent evolution adapting to marine environments, so the fins are not all homologous. They are found ...

continuous with a very short first spine, there are a 10 spines which progressively become higher towards the tail, the first rays in the soft-rayed portion of the dorsal fin is only slightly higher than the spiny portion giving the dorsal fin an almost straight profile. The soft-rayed part of the dorsal fin contains 26-28 soft rays. The

anal fin Fins are moving appendages protruding from the body of fish that interact with water to generate thrust and help the fish swim. Apart from the tail or caudal fin, fish fins have no direct connection with the back bone and are supported o ...

has 3 spines and 27-28 soft rays. The soft portion of the dorsal fin is notably longer than they spiny portion. It has small

pectoral fin Fins are moving appendages protruding from the body of fish that interact with water to generate thrust and help the fish aquatic locomotion, swim. Apart from the tail or caudal fin, fish fins have no direct connection with the vertebral column ...

are small with the uppermost rays being the longest. The

pelvic fin Pelvic fins or ventral fins are paired fins located on the ventral (belly) surface of fish, and are the lower of the only two sets of paired fins (the other being the laterally positioned pectoral fins). The pelvic fins are homologous to the hi ...

s are also small and are located below and to the rear of the

s. Sea sweeps are grey ventrally, often with a tinge of blue, green, or sometimes brown. The belly is silvery. There are two indistinct dusky bands on the upper sides. This species can reach a length of 40cm and 3.5kg.

Distribution

In Australia the species is known from the southern coast of New South Wales, around the south of the country and north to the central coast of Western Australia, and in Port Phillip Bay, Victoria.

Habitat and biology

Sea sweeps are a schooling species that are seen in small aggregations to large schools often feeding on plankton. Adult sea sweeps are found on coastal

reefs A reef is a ridge or shoal of rock, coral, or similar relatively stable material lying beneath the surface of a natural body of water. Many reefs result from natural, abiotic (non-living) processes such as deposition of sand or wave eros ...

at depths down to at least , It feeds on

plankton Plankton are the diverse collection of organisms that drift in Hydrosphere, water (or atmosphere, air) but are unable to actively propel themselves against ocean current, currents (or wind). The individual organisms constituting plankton are ca ...

over rock reefs where it forms schools while juveniles settle in

tide pools A tide pool or rock pool is a shallow pool of seawater that forms on the rocky intertidal shore. These pools typically range from a few inches to a few feet deep and a few feet across. Many of these pools exist as separate bodies of water only ...

and can be found in the

brackish Brackish water, sometimes termed brack water, is water occurring in a natural environment that has more salinity than freshwater, but not as much as seawater. It may result from mixing seawater (salt water) and fresh water together, as in estuari ...

waters of

estuaries An estuary is a partially enclosed coastal body of brackish water with one or more rivers or streams flowing into it, and with a free connection to the open sea. Estuaries form a transition zone between river environments and maritime environm ...

. They

spawn Spawn or spawning may refer to: * Spawning, the eggs and sperm of aquatic animals Arts, entertainment and media * Spawn (character), a fictional character in the comic series of the same name and in the associated franchise ** ''Spawn: Armageddon' ...

in the winter with the peak breeding season between May and August. The eggs are pelagic. The young fish grow very quickly for the first 2–3 years but growth slows down significantly after sexual maturity, although they may live over 50 years. Sea sweeps have separate sexes.

Taxonomy

The sea sweep was first formally described by John Richardson in 1848.

Fisheries

The sea sweep is of secondary importance as a target for commercial fisheries and is caught using

purse seine Seine fishing (or seine-haul fishing; ) is a method of fishing that employs a surrounding net, called a seine, that hangs vertically in the water with its bottom edge held down by weights and its top edge buoyed by floats. Seine nets can be de ...

s and trap nets.

References

{{Taxonbar, from=Q2691248 aequipinnis Taxa named by John Richardson (naturalist) Fish described in 1848