Coastal Aquaculture and Mariculture

Unit 5 - Major groups of Fisheries in India

5.1.5. Indian mackerel
The mackerels are shoaling pelagic fishes belonging to the family, Scombridae. It is the second important species after the oil sardine in India. The well-being of the marine fishing industry of India is determined to a large extent by the sustaining yields from the mackerel fishery. The bulk of the mackerel landings are contributed by a single species, Rastrelliger kanagurta (Indian mackerel). In addition to this, species such as R. brachysoma (Short mackerel) and R. faughni (Island mackerel) have also been reported to occur in India. However, their occurrence is very rare.
Distribution
Global
It occurs in coastal bays, harbours and deep lagoons in some turbid plankton rich waters. It is widely distributed in the tropical regions of the Indian and Pacific oceans, extending from the African coast to Australia i.e., between Latitude 300 North and 300 South and Longitudes 300 East and 1600 West. But it is only in Indian coast this species is highly exploited.
India
It occurs all along the east and west coasts of India from Karwar in the Northwest coast to Calcutta in the Northeast coast in the inshore waters up to 25 m. Dense shoals of Indian mackerel appear regularly from Sep - Mar along the west coast of India from Ratnagiri in the north to Kollam (Quilon) in the south. More than 75% of the total mackerel catch of the country comes from the west coast and the fishery until late 70's was mostly confined to a narrow coastal belt of a width of almost 10 nautical miles.
Production trend
It constituted on an average 8.6% to the total marine fish production in the country during 1985 - 2000. During the last decade (1990 -1999), the average annual catch of this species amounted to 0.19 million tones. Though distributed all along the Indian coast, the resource supports a fishery of high magrtitude along the west coast where it contributed 10.2% of the total marine fish catch during 1985 -2000 whereas the east coast was only 4.9%. Along the west coast, on an average 84.6% of the total landings were made. Along the east coast from where 15.4 % of the catch is realized, Tamil Nadu and Pondicherry dominate.

Recent production
It contributed 6.78% in 2002 to 10% in 2005 % to the total pelagic fish landings in India during 2001 - 2006. Its contribution to the total marine fish production ranged from 3.64 % in 2002 to 5.52% in 2004 during 2001 - 2006.

(Source: CMFRI, Annual Reports)

State-wise composition (during 1956 -2000)

Fishing season
It is from August to December along the west coast and from December to May (Peak: March -April) along the east coast.
Mode of exploitation
Beach seines, boat seines, drift net, gill net and cast net are the common traditional gears and dug-out canoes, canoe boats, catamarans and plank-built boats are the common crafts used for catching Indian Mackerels. However, bulk of the catch is mainly by large seines. Ring seines are very common in Kerala and purse seines in Karnataka and Maharashtra. Ring seines and purse seines together contribute bulk of the total mackerel catch in India. In other states, gill net is the dominant gear. Trawl net is slowly emerging as a main gear.
Size composition
The commercial fishery exploits mackerel of 18 cm size which are six months old. West coast catch comprises of size ranging from 110 to 150 mm and east coast from 175 - 215 mm. The major contribution to the commercial catch comes from 0-year class. About 80 -90% of fish in the commercial catch comes from size below 22 cm.
Food and feeding
It is a plankton feeder feeding to a greater extent on small zooplankton (cladocerans, ostracods, larval polychaetes etc.) and comparatively to a lesser extent on the phytoplankton (diatoms). Adult individuals feed on macroplankton such as larval shrimps and fish.
Size at first maturity
It is found to be between 190 and 220 mm.
Spawning season
They start maturing by around December. They become mature and start spawning by February. Intensive spawning occurs from Apr/May - July. Spawning intensity increases and reaches a peak by May. Peak spawning period coincides with south-west monsoon along the west coast and with north-east monsoon along the east coast.
Age and growth
Maximum size recorded is 390 mm.
Utilization
It is consumed fresh or in cured conditions. More than half of the mackerel catches are dried with or without salt. Consumption of fresh fish started gaining momentum recently.
Management
Even though there is no sign of over exploitation, growth overfishing is bound to occur as fishes below 15 cm size form about half of the catch. Hence, it is necessary to increase mesh size of large seines to 35 mm.