Oil Sardine Fish

Among the Indian coast, the oil sardine. Sardinella longiceps Valenciennes, 1847 is a neretic-pelagic clupeoid fish, which occurs on both west and east coast of India. It is a shoaling species of the west coast of India particularly. Such is the importance of the species that it is known as provider for the family. Although for centuries, there has been a massive fishery for the oil sardine, it was only during the last 50 years, scientific investigations have been made. An average catch of 2.5 lakh tonne have been taken annually during the current decade. However, it is a highly fluctuating fishery and the contribution of oil sardine to the marine fish landings in India is 1-33%. During 1989, 239216 tonnes of oil sardines have been landed in the country.

Distribution

The oil sardine has a general distribution from the Gulf of Oman along the Makhran coast of Pakistan along the West coast of India around Sri Lanka, east coast of India upto approximately Vishakapatnam. Where as the general confined distribution, oil sardine occur in massive shoals mainly along the south west coast of India (Kerala and Mysore coast). It is of interest to note that very large shoals of Sardinella longiceps occur in Somalia coast.

Fishing seasons

During July-August period, juveniles appear along the coast and by September, December, they form a large proportion of the catch. By January-February the number of juveniles have been drastically reduced and mostly 1 year and above age groups are taken. With the onset of pre-monsoon showers, the approximately 1 year group enter the inshore with ripening gonads from approximately June. The spent resting adults will start appearing with the juveniles during January-February, disappear from the area during February-June and reenter with the vargin spawners for second spawning.

The main reason seems to be a gradual increase in temperature from South to North from September to May and this might induce the shoal to move in a northernly direction along the coast. Chidambaram (1950) found that the temperature of 26⁰-28⁰ C is the favourable for inshore migration of the oil sardine, particularly the juveniles and he found that temperature over 29⁰ C during March to May causes the offshore disappearance of the adult fish. He also pointed out that the specific gravity of the sea water during March to May goes above 1.023, which may also account for the disappearance of adults from the inshore areas. Niar (1959) feels that the shore ward migration of the spawners during the monsoon season as well as the outward migration into the deeper waters during the post monsoon months are for spawning purposes.

There is little doubt that the shoaling of oil sardine, particularly of ‘0’ and ‘1’ year classes in the inshore waters is only for the purpose of feeding on the phytoplankton bloom. Among the important phytoplankton, which the oil sardine feed on are:

1. Fragillaria oceanica

2. Coscinodiscus

3. Pleurosigma

4. Dinoflagillates during summer months.

The copepods appear in the diet for most of the year, but are far less important than they were in the diet of the larval fishes. The oil sardines avoid Noctiluca blooms.

Migration

The migratory behavioural pattern has still got to be clearly defined. But most of the evidence point towards the initial appearance of the shoal towards the southern part of the Indian coast with roughly northernly migration of shoal.

Balan (1962) studied the shoaling behaviou of oil sardines in some detail. He classified shoals as follows:

i) Surface shoals:

a) Flipping -- when fish flips out of water being on surface

b) Pattering -- Pattering of water without coming out of water.

c) Rippling --Making small ripples or waves on water surface.

d) Leaping --when leap out of water regularly.

The above classification is based on the physical behaviour of the individual fishes of the shoal.

The colour effect of the shoal are as follows:

1. Bluish colour

2. Pinkish shoal

3. Lumniscent shoal

Bottom shoals do not come to the surface. Of these there are following types.

a) Bubbling shoal -- Making bubbles, which come out to the surface in form of forth.

2. Odoriferous shoal –Secretes mucus having strong and peculiar smell.

The most common of all these shoals are

1. Bluish shoals

2. Rippling shoals  Surface shoals

3. Bubbling shoals Bottom shoals

Lesser common are the leaping shoals and the luminescent shoals. The shoals are capable of moving in a speed of 3-5 kms. Per hour for surface shoal. The shoals extends from a minimum of 1 sq. metre to 500 square metres. The depth of the shoal normally are 0.5-8 metres.

From the fishermen’s report it appears that in highly turbid waters, highest catches (largest shoals) are to be encountered compared to clear water conditions. The discolouration of water is mainly due to turbulence, seems to have an attraction for shoaling oil sardines and during the months of September-October or even to November, when skies are overcast with dark cloud, the oil sardine shoals seem to be attracted towards the shore.

Size and Age Composition of the Commercial Catches

From 1933 to 1968, the landing datas have been analysed in general it has been noted that 100-140 mm.size group is the main mode, which contribute to the fishery. These are 0 year class just coming on to the 1 year i.e. juveniles. To a lesser extent, the 1 year group fish (150-170 mm.) contribute to the fishery. With 2 year and above class of fish, between 180-220 mm.make negligible contribution to the oil sardine fishery, which are heavily drawn upon by commercial fishing, from the basic stock, where as there are 2^nd year life of the oil sardine, the fish are not exploited.

That the gears being used traditionally are, normally of mesh size 14-66 mm.and the analysis of data make it quite apparent that the fresh recruits to the basic stock (i.e.juveniles below 100 mm.in length) and adults of 2 years and above (fish above 180 mm.in size) are not captured in appreciable numbers. Analysis of that 33 years landing data makes it obvious that the basic stock of oil sardines can easily be sustained without damage in such commercial exploitation. In the future, before introducing small meshes of high speed large mesh gear, it would be best if the parameters of natural mortality and the effect of these efficient gears on the basic stock are first determined.

Relation of Oil Sardine Population to Other Fisheries

There is a dual pelagic-neritic fish population relationship along the coast of India particularly oil sardine and Indian mackerel, R.kanagurta. A study of commercial catches since 1925 has revealed, that there seems to be an inverse relationship of the occurrence of oil sardines to that of mackerels i.e. if in a season oil sardine fishery is a good one, then the mackerel is a failure and vice versa. The reason, why this should be so are still obscure and is probably such a fluctuations in catches from season could be due to:

1. most of the catches are taken in a shallow waters by the boat seines and shore seines (Rampani net). Simultaneously fishing operations have never been carried out in the 50-100 fathom contour offshore. Thus it is likely that either oil sardines or of the mackerel are equally abundant and available in the same zone though in different depths;

2. the recruitment to the fishery of juveniles may also result in a super abundance of the oil sardines and these abundant fish population may so drastically reduce the phytoplankton blooms ,close to inshore, so that the zooplankton bloom is essential for attracting shoaling mackerel, there is naturally a paucity of mackerel during that particular fishing season in the inshore waters.

Exploitation

The chief craft in use for exploitation of oil sardines are,

1. Dug outs (Odam, Vanchi) in Kerala coast

2. Canoes (Thoni) in Kerala coast

3. Out trigger boats in Maharashtra and Mysore coast

The important gears used for capturing oil saedines are.

1. Engulfing nets or boat seines (Mathikolivala, Pattenkolivala, Odam Vala,

Paithuvalal)

2. Shore seines (Rampani)

3. Gill nets—both drift & set gill nets

(Mathichalavala).

Among them Mathikovivala, Pattenkolivala, Rampani and Mathichalavala are important. The shore seine, Rampani is possibly the most efficient, whenever it is utilised.

Fishing Areas

Roughly the west coast lying between 8 ^oN-16 ^oN represents the most intense cocentration of oil sardines shoals and accounts for the bulk of the Indian catches of the oil sardines, particularly the area around 11 ^oN witness the densest shoaling of the oil sardines. Most of the shoals are captured almost from the shore line to an off shore depth of 15 metres approximately. This roughly represent a belt of 12-15 kms.from the shore.

Fishing Season

The shoal starts appearing in the coastal waters in early June, but commercial fishing start from July to March with maximum intensity in October to January.

Factors Affecting the Fishery

Main factors affecting the oilsardine fishery appears to be as follows:

1. Abundant blooms of Fragillaria oceanica, Coscinodiscus and Pleurosigma due to the upwelling of coastal waters with the onset of south west monsoon.

2. Minimum average rainfall of 30 mm. daily for successful spawning.

3. Water temperature not exceeding 26 ^oc for shoaling for which successful south west monsoon is required.

4. Variations in the pattern of coastal current. The catches are maximum during the period (winter season), when the nothernly drift gets established along this coast. It is quite possible that the pelagic fisheries of the Indian west coast are intimately related to these coastal drift.

The fishery may, therefore, be forecasted considering the above points.

Fishing Industry

The mode of disposal of oil sardine landings in India are as follows:

1. Fresh: A major bulk of the catch is disposed off in fresh condition at a

price of Rs.73/-to Rs.250/-per tonne.

2. Canning and Freezing: In recent years a few companies in Kerala started

canning of oil sardines. But they could not compete the international market and the internal consumption is also very little.

3. Curing: Some of the catch is cured by sundrying and are exported to Sri

Lanka. But with the increasing demand in fresh conditions locally, the

curing has been stopped.

4. Oil Sardine Oil: Extracted from the body muscle, this oil utilised in

painting boats, patching of jute, dressing of leather and tampering of metals. In 1968-69,670 tonnes of oil was produced.

5. Fertilizers: The press cake or guano is also used as fish meal for live stock since it contains clacium, phosphate. An annual production of 37 tonnes of fish meal are obtained from Kerala.

The future of oil sardine fishery will depend on

1. Present status and better utilisation of the catch.

2. Mechanization and exploitation of offshore grounds for better catch.

3. Investigations on the dual pelagic neritic relationship with mackerel.

4. Intensive tagging for understanding;

1. migration pattern;

2. spawning behaviour and spawning ground;

3. precise growth data;

4. population studies—one or more discrete populations;

5. range of movements of individual shoals.

v) Improved technology for perfection of sardine oil and make it as substitute for menhaden oil in Japan.