Coastal Aquaculture and Mariculture

Unit 5 - Pelagic fisheries

5.1.8. Ribbonfish
The ribbonfishes (Hair-tailor Cutlass) are shoaling pelagic fishes. They belong to the family, Trichiuridae. They are primarily marine, but occur in the estuaries too. This group is comprised of Trichiurus lepturus (Grey ribbonfish), T. russelli (Short tailed hair tail), T. gangeticus (Ganges hairtail), Lepturacanthus savala (Silver ribbonfish), L. pantuli (Coromandel hairtail), Eupleurogrammus intermedius, E. muticus (Small head hairtail) and E. glossodos (Long tooth hairtail). Of these species, Trichiurus lepturus is the most common ribbonfish species. They are caught almost all along the Indian coast. They form an exclusive fishery of considerable importance in Andhra Pradesh, Tamilnadu and Kerala.
Distribution
Global
They are distributed in the Atlantic and Indo-Pacific regions.
India
They are distributed all along the coast with abundance in the northwest and central east coasts.
Production trend
The ribbonfish extends all along the coasts of India with varying intensity in the different maritime states. The ribbon fish landing in India has shown an increasing trend with considerable annual fluctuations. On an average, it formed 4.4% of the total fish landings and 7% of the pelagic landings during 1956-2000. They are exploited all along the coast of India and the bulk of the landings during 1956-2000 came from Gujarat and Maharashtra, followed by Kerala, Tamil Nadu and Andhra Pradesh. The contribution by other states was less than 10%. In the nineties, nearly 39% of the ribbonfish landings came from Gujarat, followed by Maharashtra (27%) and Kerala (11%). The contributions by other states were much less. Juveniles of T. lepturus measuring less than 30 cm are normally discarded, since there is no market value. Plenty of juveniles are landed along with the trash fishes by the trawlers during the recruitment season.

Recent production

(Source: CMFRI, Annual Reports)

Species composition
Of the several species of ribbon fishes, Trichiurus lepturus is the dominant species forming more than 95% of the total ribbon fish landings. Other species are caught in less numbers. These are mostly reported from northeast coast (Andhra Pradesh and Orissa) where they together constitute about 14% of the ribbonfish catch. The contribution of species other than Trichiurus lepturus is only 5% of the total ribbonfish production in India.

Size composition
The maximum size of ribbon fishes ranges from 50 cm (T. gangeticus) to 234 cm (T. lepturus), grows to larger size and fish measuring > 1 m total length are common along the Indian coast. Fishes of one year old and above dominate in the fishery along the west coast and their mean length ranges from 58 to 69 cm. In the east coast, the fishery depends on 0-year class fish having the mean length varying from 42 to 50 cm.
Fishing season
The ribbonfishes move to the inshore areas of the continental shelf during monsoon, remain close to the shore in areas less than 60 m depth in the post monsoon period and contribute abundantly to the fishery. This migration is mainly for feeding purposes. The place where the continental shelf is narrow and gradient is steep the stock becomes unavailable to the fishery leading to an off-season. The place where the continental shelf is narrow and gradient is steep the stock becomes, unavailable to the fishery leading to an off-season. If the continental shelf is wider and gradient is low, it always remains in the fishing ground and is accessible to the fishing gears throughout the year. Hence, ribbon fishes are landed round the year in both the coasts. In southeast coast and Gulf of Mannar, the shelf is narrow, leading to a seasonal fishery, restricted to a few months in the monsoon and post monsoon periods. The ribbon fish has a prolonged fishing season, extending from July to April but the peak varies from area to area. In West Bengal, it is from November -February whereas in Orissa, July to November. In Andhrapradesh, the season is from August to December while it is from November to January in Tamilnadu and September to December in Maharashtra. The peak production in the national level is generally from October –December.
Mode of exploitation
The principal gear is trawl net. This gear landed 74% of the catch during 1991-2000. The other gears are dolnet, drift gill net, boat seine, shore seine, etc. The mechanized sector (trawl net, gill net, purse seine and others) contributed about 85% and the rest is from the non-mechanised and outboard-motorized sectors.
Food and feeding
All the species of ribbonfishes are highly carnivorous, predominantly piscivorous and occasionally cannibalistic too. They are voracious feeders, feeding both during day and night. They prefer small and medium size fishes, prawns and shrimps.
Size at first maturity
The size at first maturity of the most common species, Trichiurus lepturus is 46 -47 cm when it is about 1 year old. It is 30cm in E. intermedius and about 43 cm in E. muticus.
Spawning
T. lepturus has a prolonged spawning in some areas. On the west coast, the peak spawning is in April - June. In the east coast, it spawns during February to June with peak in May. Another short duration spawning also has been reported in November -December.
Fecundity
T. lepturus is found to lay up to 1, 34,000 ova depending on the size and age. It is from 4000 (42 cm) to 16,000 (60 cm). The fecundity of E. intermedius varies from 2349 (40.9 cm) to 9950 (45cm). In E. muticus, it is from 1327 (49.5cm) to 2087 (55.lcm) and in L. savala it varies from 9178 (37 cm) to 17347 (54 cm).
Utilization
In India, three decades ago, they were low priced fishes preferred only by the poor. Large fishes were consumed fresh and transported even to the interior markets, but the smaller ones, in excess of the local requirements, were usually sun-dried on the beach. But at present, they are significantly important in the export market. Currently, large quantities of ribbon fishes are exported in the frozen form to China, Japan and other Southeast Asian countries. During 2000-01, it formed 30% of the total seafood exported and 63% of total frozen finfish exported. This shows that the ribbon fish resource plays a key role in the marine product export of India. Only undamaged fresh fish are considered for export. Ribbonfish formed 56% of total frozen fish export (quantitywise) - 81720 tonnes; valuewise - 35% (Rs. 638.7 crores). Ribbonfish stands first position in the export of frozen fish -both valuewise and quantitywise. The local people consume large sized fresh fish while the undersized are sun-dried. A portion of the dried fish is sold in the interior markets and the rest is exported to Southeast Asian countries like Sri Lanka, Malaysia, Singapore, Thailand, etc. The under-sized fish brought ashore goes with the trash and are utilized in fishmeal production.
Conservation and management
In a multispecies fishery, it is impractical to regulate the exploitation of a single resource like the ribbon fishes. The ribbonfish landings have been showing annual fluctuations but still it has been maintaining an increasing trend of slightly higher-magnitude in recent years. This is due to resource abundance on one hand and increased exploitation on the other. The export market has paved the way for targeted fishing of this resource recently leading to certain degree of over exploitation in major centres, especially along the east coast. It is necessary to control the exploitation during the period of abundance through various regulatory measures.