A NOTE ON THE BREEDING HABITS OF A COMMON , ANGUILLA BENGALENSIS GRAY AND HARDW.

BY M. RAHIMULLAH, SYED MAHMOOD AND S. A. KABIR (Department of Fisheries, Ityderabad-Deccan) RcceivedDecernbcr 9, 1943 (Communicated by Prof. A. 8ubba Rau, D.SC.) HAMtD KHAN from Punjab, Mukerjee from Calcutta, Sunder Raj from Madras have done some useful work on the development and breeding habits of some fresh-water and on marine fishes some valuable work has been conducted by the Madras and Travancore Fisheries Departments and also in the University Zoological Laboratory, Madras. Besides these Jones and Job have done some work of this nature on Larvicidal fishes also. Regarding migratory fishes Hora has done extensive work on the ana- dromous , Hilsa ilisha Ham. which comes to fresh-water for breeding from the sea during the floods and he asserts that it breeds even in closed water, and does not migrate to the sea at all. On the other hand, Sunder Raj and Naidu who have been working on this fish in Cauvery, Godavari and Kistna are of opinion that it is essential for the ttilsa to go to the sea after breeding in fresh-water and its migration is essential. In this paper we are dealing with a Catadromous fish Anguilla which belongs to the .4podes and Genus Anguilla. Extensive researches have been done on ,4nguilla anguilla and other allied species by many European workers and especially by the Danish Ichthologist Professor Schmidt who has traced the life-history in much detail. He was able to locate the breeding places near Sargasso sea in the Altantic very far from European coast. As it is well known, he has shown that Anguilla migrates from fresh-waters to the sea; gonads become mature only when it reaches salt-water; fertilisation takes place in the sea and LeDtocephalus or larval stages migrate first with the currents towards the land, then finally enter fresh-water and change into the Elver stage which is a small form of Anguilla, the growth in size takes place in fresh-water. Further, the elver stage is reached after or about the age of 5 years and scale-formation starts only when they reach a size of about 8 inches. In its geographical distribution eel shows very interesting features. The whole of America, South as well as the North, has no on its Pacific shores, whereas Japan, China, part of Australia and South have eels in most of their lagoons and rivers. In the fresh-waters which flow into 16 Breedi~zg Habits of Common Eel, A. bengalensis Gray & IZardw. 17 that sort of inland sea bounded on the north by Cochin China, on the west by the Malay Peninsula and the island of Sumatra, on the south by Borneo and Java, no sign of an eel is ever seen. On the other hand, there are swarms of eels in the rivers of Java and Borneo which empty themselves into the . It has been found that the regions which have eels in their fresh-waters are always bordered by seas of exceptional depth, or are visited by currents which pass over those depths. The situation becomes clearer when we remember that when eels are very young, while they are still fry, they come from the sea, that they begin life far out at sea and live there for a time before they begin to penetrate the rivers. They are originally deep sea creatures. Rising from the depths to approach the shore and enter the rivers, the parti- cular part of the land to which they will go is determined by the part of the

a, b and e. x50. Different patterns of scales from Anguiila bengalensis, measuring 11m. d. • A scale from a specimen 19" in length showing one growth ring. e. x 1. Young specimen of the same fish measuring 6" having no scales. sea from which they come. They can only approach the land when their home in the sea is within immediate reach. The problem was suggested to us by Professor R. Gopala Aiyer as he was of opinion that belonging to the same genus and family our eels may also have the similar habits and will go to the sea for breeding. During the month of September 1943 while on tour, one of us noticed swarms of small worm-like creatures which were trying to go up the current when the flood gates of Nizamsagar were opened. After catching some B2a 18 M. RahimuUah and others they were found to be young ones of eels the smallest being 6 inches long. More specimens were caught and preserved. To ascertain their age, the skin was carefully scraped and it was found that the smallest specimens of 6" had no scale formation, but the scales were present on specimens of 11 inches and upwards. As will be clear from the three types of scales found on this specimen of 11", no annual rings have formed and if we accept the deductions in the case of European eels this most probably was about 6 years old as the scale formation starts only after 5 years. Scales from a specimen of 19 inches were about double the size of the former and showed clearly only one growth ring which means that it may be a year older and of about 8 years of age. These are some of the results obtained after scale reading but further work regarding the growth rings on the otoliths is under progress. Collection of a large number of speci- mens is also contemplated when the condition of their gonads will be studied and further data will be collected. Nizamsagar dam is about 450 miles from the sea situated across the River Manjra which is a tributary of the Godavari. The Godavari falls into the Bay of Bengal and there are anicuts near Rajahmundry, a precipitious ascent near Bhadrachellum and another anicut near Dummugudam; the course in H.E.H. the Nizam's territory is mostly rocky, and the flow of water very swift. Now, arise some questions and doubts about the ascent of 'elvers' from the sea to the river. Where does the fish breed ? If it does so in the sea, is it possible for the young ones of such a small size to travel a distance of 450 miles against the current ? Does the fish breed in fresh-water ? We are of opinion that most prob- ably it breeds in fresh-water and has left its habit of going to the sea as has been shown by Dr. Hora for the anadromous fish, hilsa that it does not go to the sea at all and it grows and breeds in the closed waters near Pulta Reservoir and other places. It is an interesting problem and research workers situated near the estu- aries will be in a better position to solve it as it would be a very remunera- tive concern for the fisheries if its breeding habits are fully worked out.

REFERENCES Boulenger, G.A. .. Fishes, C. N. It. (1932). Day, F. .. Fishes, Fauna Brit. Ind., Vol. II (1887). Kyle, H.M. .. The Biology of Fishes, 1926. Roule, L. .. Fishes, Their Journeys and Migrations, 1933.

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