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Yellowtail trumpeter

The Yellowtail trumpeter, Amniataba caudavittata, (also known as the Flagtailed terapon, Yellowtail grunter and Yellow-tailed perch) is a common species of coastal marine fish of the grunter family; Terapontidae. The Yellowtail trumpeter is endemic to Australia and Papua New Guinea, ranging from Cape Leeuwin in Western Australia along the north coast of Australia to Bowen, Queensland and north along the coast of southern Papua New Guinea. The species is distinguishable by its colouring patterns, as well as anatomical features such as spine and gill counts.

The species commonly inhabits estuaries during the warmer months of the year, moving offshore in winter to avoid the influx of fresh water from swollen rivers. The species breeds in the upper reaches of estuaries, with an average of 310,000 eggs produced per individual in a season. The Yellowtail trumpeter is a benthic omnivore, preying on algae, crustaceans and polychaetes predominantly and shows a change in diet with age.

The species is often taken by with handlines, seines, and other inshore fishing gear but is considered to be a relatively poor table fish. The Yellowtail trumpeter is of no relation to the true trumpeters of the family Latridae.

Taxonomy and naming

The Yellowtail trumpeter is one of three species in the genus Amniataba, which is one of fifteen genera in the grunter family, Terapontidae. The grunters are Perciformes in the suborder Percoidei.

The species was first described by Richardson in 1844 as Terapon caudavittatus, before he subsequently republished the species under the names Datnia caudavittata, Amphitherapon caudavittatus and the currently accepted binomial name of Amniataba caudavittata. The reasons for all the synonyms are not clear, either Richardson didn't know he was redescribing the same species, or he changed his mind as to which genera the species belonged in. Castelnau redescribed it once again as Therapon bostockii in 1873. All names except Amniataba caudavittata are invalid under the ICZN rules.

The species has a number of common names, with the name Yellowtail trumpeter the common in usage, even though the species has no relation to the 'true' trumpeters of the family Latridae. Other names include Yellowtail grunter, Yellow-tailed perch and the name used by the FAO; Flagtailed terapon.

Description

The Yellowtail trumpeter is a moderate-sized species, growing to a maximum size of 28 cm, but more often observed at around 15 cm. The body is quite deep in profile and is compressed laterally. The upper jaw is slightly longer than lower jaw. The first gill arch has 6 to 8 gill rakers on the upper limb and 12 or 13 on the lower limb. The dorsal fin has 12 or 13 spines and 8 to 10 soft rays, the spinous part of dorsal fin is curved, with the fifth spine being the longest, and the final spine the shortest. The anal fin has 3 spines and 8 or 9 soft rays, with the second anal-fin spine longer than third, but shorter than longest anal-fin rays. The pored scales in the lateral line number 46 to 54 with 7 to 9 rows of scales above lateral line and 17 to 19 below it.

The colour of the upper portions of the body is grey, with only light pigmentation on the lower part of the body. The upper half of body has a number of dispersed spots somewhat smaller than the pupil, while some individuals have 5 or 6 incomplete vertical bars extending from the dorsal fin surface of body, down to the level of the pectoral fins. The fins are generally yellow in colour, with a variety of dusting and blotching. The spinous dorsal fin has irregular spotting and a faint duskiness distally, but does not exhibit a distinct patch of dark pigmentation. The soft dorsal fin is dusky at the base while the spinous portion of anal fin is also slightly dusky. The caudal fin is also spotted basally, with a highly distinct, black blotch extending obliquely across each lobe.

Range and habitat

The Yellowtail trumpeter ranges along the north coast of Australia from Cape Leeuwin in Western Australia eastwards to Bowen in Queensland, also extending north to southern Papua New Guinea.

The species is known to tolerate a very wide range of salinites, from fresh river waters to hypersaline waters found in some areas of Shark Bay and everything in between. Yellowtail trumpeter often inhabit estuarine waters along the Western Australian coast, as well as sand and seagrass beds in inshore and offshore waters of the continental shelf.

Biology

The Yellowtail trumpeter is a seasonal inhabitant of many estuaries in Western Australia, with the species most abundant in summer due substantial recruitment of juveniles following the spawning period in early summer. During colder months, they tend to move into deeper offshore waters to avoid the large influxes of fresh water entering the estuaries from upland river systems.

There has also been evidence provided that suggests Yellowtail trumpeter naturally hybridises with another species of freshwater terapontid, Leiopotherapon unicolor, on occasion.

Diet

The Yellowtail trumpeter is a benthic omnivore, exhibiting a change in diet over the life of the individual. The younger age class feeds primarily on algae and a range of small crustaceans, while older fish prey to a greater extent on polychaetes.

Life cycle

Most individuals of the species reach sexual maturity at the end of their second year, with some large fish mature after only one year. The fish spawn in estuaries, with a number of studies focused on the population of Swan River in Western Australia. Here they spawn in the upper reaches of the estuary in a period from November to January, producing an average of 310,000 egg in a season. The spawning period is associated with a lull in the freshwater influx of the river, resulting in fairly stable salinity and temperature regimes. This allows the species to be very successful in the Swan, and other rivers.

The mature, unfertilised eggs of the Yellowtail trumpeter are small and spherical, having an average diameter of 560 μm. The larva are pelagic and characterized by an elongate body, which becomes moderately deep and laterally compressed during development. The species grows seasonally, with growth only occurring in the warmer months of the year. Yellowtail trumpeter live for at least 3 years.

Importance to humans

The Yellowtail trumpeter is of minor commercial importance throughout its range, caught with handlines, seines, and other inshore fishing gear. It is not considered particularly good table fare, and considered a nuisance by many recreational fishermen who target bream in estuaries.