India's Central Marine Fisheries Research Institute (CMFRI) has identified the new species of mackerel in Kerala waters. The state of Kerala has nearly 600 km of Arabian Sea shoreline.
The black-spotted fish, round and more fuller in shape than regular mackerel, has soft flesh, and has been named 'Indian Chub Mackerel' (Scomber Indicus) by a team of CMFRI scientists.
The team, led by E M Abdussamad, published their work on the discovery in the Indian Journal of Fisheries. Their report says the new species is distinctly different from other members of the mackerel family, both taxonomically and genetically.
CMFRI has its headquaters at Kochi, a major port city on the South-West coast of India. The team of scientists have described Scomber Indicus based on the specimens collected from the eastern Arabian Sea.
The report says the "species is differentiated from its nearest congener Scomber australasicus, in having 29-32 gill rakers on lower limb of first gill arch, posterior, most part of hypohyal blunt, with presence of a pit between the hypohyal and the ceratohyal, and also in having a posteriorly directed haemal spine which is deeply curved in the basal region."
The report adds: "Genetic differentiation and divergence between the newly described species and the four valid species of the genus Scomber - S.scombrus, S.japonicus, S.australasicus and S.colias - were compared using cytochrome c oxidase 1 and cytochrome b gene sequences. The new species was found closest to S.colias."
CMFRI director A Gopalakrishnan says the new species will add to the marine wealth of the shore, and that it has been making waves since it was first netted last year.
He added that though 10 tonnes of the Indian Chub Mackerel was caught in 2015, it has grown to 25 tonnes so far this year. However, this year's catch has revealed lengths of 9-15 cms, indicating that the fish are not fully grown as yet.
Mr Gopalakrishnan said though last year’s catch was mostly mature mother fishes, the catches this year show more of juvenile ones, clearly indicating that the species has made the shore their home and spawned this April and May, before the monsoon season set in.
This year, the species is only visible in Kerala waters. E M Abdussamad, Principal Scientist, CMFRI, said reports of regular catches and landings of the new species were coming in from Vizhinjam, Alappuzha, Kollam and Kozhikode in Kerala.
First spotted along the Gujarat coast last year, the Indian Chub Mackerel started appearing along the Western coast, all along till Kanyakumari in the South. The towns of Alappuzha, Ernakulam, Kollam, Vizhinjam and Kozhikode coast in Kerala have recorded maximum presence of the species.
The new species is being monitored continuously to understand its biology and interaction with other species.
Incidentally, CMFRI officials point out that mackerels, of the regular variety, have been changing their habitat in the Indian peninsula. The Indian mackerel (Rastrelliger kanagurta), from being predominantly found in the southwest coast, appears to have moved up to the northern west coast of India.
The species appears to be expanding its habitat toward the northern part of Maharashtra and towards Gujarat. Though the movement of the Indian mackerel is being closely monitored, officials insist it could lead to loss of some species as mackerels are likely to feed on native fish.
Officials have pointed out that the phenomenon could change the nature of fisheries along India's 7500 km long coastline.