Arripis trutta

{{Short description|Species of ray-finned fish}} {{Use dmy dates|date=September 2022}} {{Speciesbox | image =Arripis trutta.jpg | image_caption = | taxon = Arripis trutta | authority = (J. R. Forster, 1801) | synonyms = *''Sciaena trutta'' Forster, 1801 *''Perca trutta'' Bosc, 1802 *''Perca marginata'' Cuvier, 1828 *''Arripis salar'' (Richardson, 1839) *''Centropristes sapidissimus'' Richardson, 1842 *''Centropristes tasmanicus'' Hombron & Jacquinot, 1853 | synonyms_ref =<ref name = Fishbase>{{FishBase|Arripis|trutta|month=December|year=2019}}</ref> }}

'''''Arripis trutta''''', known as the '''Australian salmon''' in Australia and as '''kahawai''' in New Zealand,<ref name=":0">{{Cite journal |last1=Leach |first1=Foss |last2=Davidson |first2=Janet |last3=Horwood |first3=Michelle |last4=Mallon |first4=Sean |date=1996-06-01 |title=The estimation of live fish size from archaeological cranial bones of the New Zealand kahawai Arripis trutta |url=https://tuhinga.arphahub.com/article/34124/ |journal=Tuhinga |language=en |volume=7 |pages=1–20 |doi=10.3897/tuhinga.7.e34124 |doi-access=free |issn=2253-5861}}</ref> is a South Pacific marine fish and one of the four extant species within the genus ''Arripis'', native to the cooler waters around the southeastern Australian coasts and the New Zealand coastline. Other common names for this species include '''Eastern Australian salmon''', '''Eastern Australian mackerel''', '''bay trout''', '''blackback salmon''' (or just "black back"), '''buck salmon''' (or "buck"), '''cocky salmon''', '''colonial salmon''', '''woolley Judith''', '''newfish''' and '''salmon trout'''.

Although it is referred to as "salmon" in Australian English and its species epithet ''trutta'' is Latin for ''trout'', it is not related to true salmons or trouts, which belong to the family Salmonidae of the order Salmoniformes. All ''Arripis'' species belong to the family Arripidae of the order Scombriformes.

==Taxonomy== ''Arripis trutta'' was first formally described in 1801 as ''Sciaena trutta'' by Marcus Elieser Bloch and Johann Gottlob Theaenus Schneider with the type locality given as Cook Strait.<ref name = CofF>{{Cof record|spid=35071|title=''Sciaena trutta''|access-date=21 April 2020}}</ref>

==Description== ''Arripis trutta'' is a streamlined fish with a long and slender body. There is a bony ridge edge of bone beneath and in front of each eye which has obvious serrations in smaller individuals. In larger fish the scales feel smooth. The lobes of the caudal fin are equivalent in length to the head. These fish are dark bluish-green dorsally and silvery white ventrally. The juveniles have golden bars on their upper flanks and these break up into large spots as the fish matures. The pectoral fin is vivid yellow and the caudal and spiny part of the dorsal fin both have a blackish margin.<ref name = FofA>{{cite web | author = Bray, D.J. | year = 2018 | title = ''Arripis trutta'' | work = Fishes of Australia | access-date = 21 April 2020 | url = http://136.154.202.208/home/species/406 | publisher = Museums Victoria}}</ref> There are 9 spines and 15–17 soft rays in the dorsal fin and 3 spines and 9–10 soft rays in the anal fin. The maximum total length recorded is {{convert|89|cm|in}} although they are commonly a total length of around {{convert|47|cm|in}} and the maximum recorded weight is {{convert|9.4|kg|lbs}}.<ref name = Fishbase/> The most consistent difference between this species and ''Arripis truttacea'' is the gill raker count, ''A. truttacea'' has 25–31 gill rakers and ''A trutta'' has 33–40.<ref name =FofA/>

''Arripis trutta'' can differentiated from ''Arripis xylabion'', as the former has a larger tail.<ref name="Secrets">{{cite Q|Q114871191|pp=170-175}}</ref>

==Distribution== ''Arripis trutta'' is found in the southwestern Pacific Ocean mostly around the littoral waters of the Tasman Sea and Bass Strait.<ref name = Fishbase/> In Australia, they are found from Moreton Bay in Queensland to western Victoria and northern Tasmania, with infrequent records at Kangaroo Island in South Australia. They are also found around Lord Howe Island and Norfolk Island in the open waters of the Tasman Sea.<ref name = FofA/> In New Zealand, they are distributed around the coasts but are more common north of Kaikōura on the South Island.<ref name = OH>{{cite web | url = https://www.oceanhunter.co.nz/NEED+TO+KNOW/Species+Identification/Kahawai.html | title = Kahawai | access-date = 21 April 2020 | publisher = Ocean Hunter}}</ref> They are also found around the Chatham Islands and Kermadec Islands<ref name = Fishbase/> east of New Zealand.

==Habitat and biology== ''Arripis trutta'' is a migratory fish that may swim long distances, sometimes thousands of kilometres. The adults congregate and form very large schools off oceanic beaches and exposed coasts coastal areas,<ref name = FofA/> and will enter rivers.<ref name = Fishbase/> The juveniles live in smaller schools in more sheltered areas such as bays and estuaries, and these mostly occur in the more southerly areas in which this species occurs. It is carnivorous and feeds mainly on small pelagic fish and crustaceans such as krill.<ref name = FofA/> They are highly visual predators, preying on a diverse variety which eat a variety of crustaceans and polychaetes during their juvenile phase, however, adults shift their preferred prey to small schooling baitfish such as pilchards, sprats and anchovies. There is some evidence that the diet of ''A. trutta'' has undergone a marked shift since the late 20th century, studies conducted during 1950s and 1960s found that the adults fed largely on krill and squid, which are animals associated with cooler waters. Studies during the early 21st century have shown that the main prey taken is small pelagic baitfish. It is thought that this shift is a result of long-term changes in the East Australian Current which brings warmer waters from the Coral Sea and has extended farther south since the 1990s. It is further thought that this "multi-decadal southward penetration of the EAC" is one of the more obvious indications of global warming and the recorded change in the diet of ''A trutta'' forms a biological record of oceanic warming.<ref name = Dubbins>{{cite web | url = https://www.fishingworld.com.au/news/fish-facts-australian-salmon | title = Fish Facts: Australian salmon | author = Dr Ben Diggles | date = 14 September 2016 | access-date = 21 April 2020 | publisher = Fishing World}}</ref>

''Arripis trutta'' are preyed on by larger marine predators such as seals, dolphins and sharks. The feeding schools push the smaller fish they are preying on towards the surface, making them accessible to seabirds, In this way, this species has an important ecological role in facilitating transfer of energy among the upper levels of the pelagic food chain in inshore ecosystems.<ref name = Dubbins/> An example is the white-fronted tern (''Sterna striata'') which has the colloquial name "kahawai bird" because often feeds on shoaling fish in association with kahawai, gulls and shearwaters. Fishers hunting for schools of kahawai to troll look out for the flocks of white-fronted terns feeding in association with the predatory fish.<ref name = NZBirds>{{cite web | url = http://nzbirdsonline.org.nz/species/white-fronted-tern | title = White-fronted tern | access-date = 21 April 2020 | publisher = NZ Birds Online}}</ref>

The Australian population of this species spawns in the surf zone between Lakes Entrance in southeastern Victoria and Bermagui in New South Wales South Coast in the late spring and summer. They first spawn when they are around four years old and have attained a length of {{convert|39|cm|in}}<ref name = MV>{{cite web | url = https://collections.museumsvictoria.com.au/species/13728 | title = ''Arripis trutta'' (Forster, 1801), Eastern Australian Salmon | access-date = 21 April 2020 | publisher = Museums Victoria}}</ref> They can live for up to 26 years.<ref name = Fishbase/>

==In a human context==

''Arripis trutta'' is a major traditional food for Māori.<ref name=":0" /> Many tribes would migrate to river mouths in summer months, when kahawai would swarm.<ref name="Secrets" /> Kahawai could be caught using flecks of iridescent pāua shells, or by using a pā kahawai, a specialised hook that incorporated pāua shell in the design.<ref name="Secrets" /> The name kahawai is specific to Māori language, as the word is not used for any similar species of fish across Polynesia.<ref name="Secrets"/>

Early European settlers to New Zealand did not like the fish, describing it as dry, coarse and flavourless. Over time the fish grew in popularity, and is now one of the most caught recreational fish in the country.<ref name="Secrets"/>

===Fisheries=== ''Arripis trutta'' are caught in coastal waters, frequently in the vicinity of estuaries and off coastal beaches. Most of the commercial landings are caught using purse seines and spotter planes may be used to find the large schools They may also be taken as bycatch of purse seine and trawl fisheries pursuing other schooling species like snapper, mackerel and trevally. Although they are fished for throughout southern Australia, the main landings are in southern New South Wales and Eastern Victoria. The flesh of this species is not very popular with consumers and a high proportion of the landings have been used as pet-food or bait.<ref name = gfbf>{{cite web | url = https://goodfishbadfish.com.au/?fish=australian-salmon | title = Australian Salmon | access-date = 21 April 2020 | publisher = goodfishbadfish}}</ref> In New Zealand the principal commercial fishing areas are north of Kaikōura in the South Island, off the coast of North Island and in the Cook Strait.<ref name = sfnz>{{cite web | url = https://www.seafood.co.nz/show-species/kahawai/ | title = Kahawai | access-date = 21 April 2020 | publisher = Seafood New Zealand}}</ref> Fisheries New Zealand manages that nation's fishery to maintain the population of ''A trutta'' at roughly 52% of the stock which was present before modern commercial fisheries began and in 2019 the population was well above that target.<ref name = FNZ>{{cite web | url = https://www.mpi.govt.nz/travel-and-recreation/fishing/fish-species/kahawai/ | title = Kahawai | access-date = 21 April 2020 | publisher = Fisheries New Zealand}}</ref>

====Recreational fisheries==== ''Arripis trutta'' are highly prized by recreational fishers, especially for anglers fishing from beaches and rocks. Anglers tend to catch this species using light tackle or by fly fishing and it is said to be a "sporting catch".<ref name = sea-ex>{{cite web | url = http://www.sea-ex.com/fishphotos/salmon_australian-catching-fishing.htm | title = Catching & Fishing for Australian Salmon (Arripis trutta) | access-date = 2 April 2020 | publisher = Sea-Ex}}</ref>

==References== {{Reflist}}

==External links== * [https://www.youtube.com/watch?v=JRPDaWNmlcQ Juvenile Eastern Australian Salmon video on Youtube]

{{DEFAULTSORT:Arripis trutta}} Category:Arripidae Category:Fish of the Pacific Ocean Category:Marine fish of Eastern Australia Category:Marine fish of New Zealand Australian salmon Category:Taxa named by Johann Reinhold Forster