Coastal Aquaculture and Mariculture

Unit 5 - Major groups of Fisheries in India

5.1.1. Indian oil sardine
The Indian oil sardine, Sardinella longiceps belongs to the family, Clupeidae. This pelagic fish forms schools in coastal waters and is strongly migratory. Of the fifty species of clupeoid fishes inhabiting Indian seas, at least 25 species are found to be commercially important. These clupeoid fishes are of great economic importance as a source of food and oil. Among the several clupeoid fishes, oil sardine is the most abundant and important one. It contributes to nearly 15% of the total marine fish production of India. This fishery is characterized by remarkably wide fluctuations on a seasonal, annual and decadal scale. The success or failure of oil sardine fishery shows a remarkable influence on the socio-economic status of fishermen to a large extent.
Distribution
Global
It is distributed in the northern and western parts of Indian Ocean only. It occurs along the coast of Somalia, Kenya, Seychelles, Middle East, Pakistan, India, Malaysia, Indonesia, Philippines and Vietnam. Very large shoals of oil sardines occur along1he Somalia coast.
India
It is distributed from Gujarat to Kerala on the west coast and Tamil Nadu, Andhra Pradesh and Orissa coasts on the east coast. Enormous schools, supporting the fisheris strike the Kerala and Karnataka coasts. Though it is available up to 50 m depth, the maximum abundance is found to be within 30 m. The optimum temperature and salinity ranges for distribution and abundance of oil sardine are 27 - 28°C and 22.8 -33.5 ppt respectively. Occasionally, they enter the estuaries along the southwest coast.
Production trend
The maximum landing of 3.01 lakh tonnes which formed 33% of the total marine catch was in 1968 and the minimum of 7,412 tonnes which formed 1 % of the total marine catch was in 1956. About 95% of the total oil sardine landings were reported only from the southwest coastal states of Kerala and Karnataka until 1980's. Catch was high in 1989 (2.89 Lakh t) and gradually declined thereafter till 1994 (47,000 t). However, since 1995, it started increasing. Since 1986, while oil sardine fishery declining along the southwest coast, there has been a phenomenal rise in the landings along the southeast coastal states of Tamil Nadu and Andhra Pradesh while in the northeastern states of West Bengal and Orissa, a new fishery has emerged from a position of almost no landings. It is a highly fluctuating fishery, contributing 10 to 20 % of the total marine fish landings of the country with an average of about 200 thousand tonnes.
Recent production
Pelagic fishes formed about 55 % of the total marine fish landings in general. Among the pelagic fishes, oil sardine alone contributed 22.54% to 28.32% to the total pelagic fish landings and 11.51% to 15.46% to the total marine landings during 2001 -2006.

(Source: CMFRI, Annual Reports)

Fishing season
Fishing season for oil sardine varies from one place to another place. It starts soon after the outbreak of monsoon in June and continues till March - April along southwest coast. Fishing is usually done throughout year except during Mar - May in Kerala, Sep/Oct - Jan in Karnataka and Goa and July - Oct in Andhra Pradesh. Usually juveniles appear during July-August period along the coast and they form a large proportion of the catch during Sep - Dec. However, 1 year and above age groups appear during Jan - Feb.
Mode of exploitation
Oil sardine fishery has been exploited by the indigenous craft and gear from very early times. This fishery was exploited by employing Artisanal fishing gears mainly boat seines, beach seines, cast nets and small meshed gill nets were employed for catching oil sardines along the southwest coast till 1970's. This fishery was confined to a narrow coastal belt of 8 to 12 km within the 25 fathom line till 1975. Fishmen started employing larger fishing gears like purse seines in the late 70's and ring seines in late 80's. In south Kerala, oil sardines are mainly caught by the one-boat boat seine ‘Thangu Vala’ and gill net 'Ayila Vala' and some purse seines. In North Kerala, boat-seine 'Pattan Kolli' is the major gear, followed by the gill net 'Mathichala vala' and the cast net. The chief crafts employed in Kerala are dugout canoes, the bigger 'odam' and the smaller 'vanchi'. Out rigger boats are common crafts in Karnataka coast. In Tamil Nadu, pair trawlers are also operated at 12 -16 m depths in Pamban - Rameshwaram area while ring seines being used in the Palk bay. At present, purse seine fleet operates at 30 - 40 m depth almost throughout the year. Motorized ring seines target small pelagics like oil sardine and mackerel fish in inshore waters during the monsoon season also. Purse seine is the most important gear at present. However, shore seine (Rampani and Vendi) and cast net are the gears commonly used for catching oil sardine.
Factors affecting fishery
I. Periodical migration into offshore waters
2. Heavy natural mortality
3.Availability of the diatoms (Fragillaria oceanica, Coscinodiscus and Pleurosigma)
4. Overfishing
5. El Nino
6. Water temperature
7. Rainfall
8. Ocean current.
Size composition
Commercial fishery comprises mainly of '0' year and '1' year old fishes. Small sized oil sardines of 0 -year class, measuring 70 to 100 mm in length dominate the commercial catches-from August to November. The bigger sized fishes of 100 to 200 mm dominate the catches in the later months during the peak season which generally extends up to January.
Food and Feeding
It is predominantly a phytoplankton feeder, feeding mostly on diatoms like Fragillaria oceanica, Coscinodiscus, Thallassiothrix and Pleurosigma. However, F. oceanica is the most favourite food item. In addition to diatoms, they may also feed on copepods, dinoflagellates, ostracods, larval prawn, larval bivalves, fish eggs and some bluegreen algae. The presence of diatoms, Fragillaria oceanica in large numbers indicates the abundance of oil sardine in coastal waters.
Age at first maturity
It attains maturity at about the end of the first year at 150 mm size. Maturation is controlled by climatic factors like temperature and intensity of rainfall experienced by the pre-spawners.
Spawning season
It grows rapidly during the first few months and matures early within its life span of about two and half years. Just prior to spawning, the oil sardine leaves, the inshore waters. It spawns only once a year and breeding season is rather short. Spawning season is prolonged with varying duration. On the west coast, peak spawning occurs during June - Aug, while on the east coast, intense spawning activity is observed during December to February. Juveniles are seen abundantly in the near shore waters during July-September.

Fecundity
It is a prolific breeder and liberates about 38,000 -80,000 ova at a time depending upon the age, size and condition of the fish.
Market
This fish is in good demand in local and distant markets and the fishery is fully exploited along the southwest coast. On the east coast, demand for local consumption is low and most of the catch is marketed in Kerala. During glut season, they are sun-dried and used for production of poultry feed. Frozen sardine is exported to countries like Japan, USA, Austria, Belgium, Spain, UK, China, Bahrain, Jordan, Kuwait, UAE, Australia, Kenya, New Zealand and Srilanka.
Utilization
A major bulk of the catch is disposed off in fresh condition. It also serves as a source for valuable by-products like sardine oil used in several industries and fishmeal for cattle and poultry feed production and as guano.

Conservation and management
There is an inverse relationship between the occurrence of oil sardine and Indian mackerel, Rastrelliger kanagurta. Destructive fishing practices like using small meshed seines should be effectively controlled by enforcing mesh size regulation (minimum 18 mm), closed season and restricted fishing (June - Sep) besides strict licensing and optimum deployment of fishing units especially ring seines and purse seines. Present coastal fishery scenario demands responsible fishing by all sectors to sustain the fishery as well as ensure the socio-economic well being of the fishermen. Necessary steps should be taken to exploit the offshore grounds to have better catch.