On the unknown postlarval stages of the garfish, Tylosurus strongylurus (Van Hasselt) and the seapike, Sphyraena jello Cuvier

Item Type article

Authors Thangaraja, M.

Download date 07/10/2021 06:12:56

Link to Item http://hdl.handle.net/1834/31798 Journal of the Indian Association 18. 1988, 369-374

ON THE UNKNOWN POSTLARV AL STAGES OF THE GARFISH, 'tYLOSURUS STRONGYLURUS (VAN HASSELT) AND THE SEAPIKE, SPHYRAENA JELLO CUVIER

M. TH ANG ARAJA*

Centre of Advanced Study in Marine Biology, Porto Novo, Annamalai University

ABSTRACT

Unknown larval stages of Tylosurus strongylurus and Sphyraena jello have been traced from Vellar Estuary, Porto Novo (lat. 11° 29'N; long. 79° 46' E). Descriptions of different stages (7-17.5 mm T. strongylurus,. and 18 and 22.5 mm. Sphyraena jello) are given. A thorough survey for 2 years (Nov. 1977 -Oct.1979) in the estuary revealed that these larvae were very rare in the estuary and were caught on one occasion (Nov.1978) only.

INTRODUCTION

The garfish, Tylosurus strongylurus, commonly inhabits coastal waters, and frequently enters backwaters and estuaries. The eggs and early larval stages of this were described by Job and Jones ( 1938). Nair ( 1952) described the postlarvae collected from the Madras coast. Venkataramanujam (1975) described a 10 mm postlarva collected from the Porto Novo coast. The 7 mm to 17.5 mm larvae collected from the Vellar estuary are described here for the first time since these stages. were not recorded by previous authors.

The common seapike, Sphyraena jello., is of delicate meat with good flavour and is in good demand. Early larval stages of this fish were described by Bal and Pradhan (1945, '46, '47, '51), Basheeruddin and Nayar ( 1962) and Venkataramanujam ( 1975 ). However, the 18 mm and 22.5 mm larvae are described here

Present address* Marine Science and Fisheries Centre, Ministry of Agriculture and Fisheries, P.O. Box: 467, Muscat, Sultanate of Oman. 370 THANGARJA for the first time.

MATERIAL AND METHODS

The larvae were callected from the Vellar estuary by a plank ton net made of bolting silk cloth, no 10, 158 mm. The larvae were sorted out and preserved 'in 5% neutralised formalin immediately after collection. Surface water temperature and salinity of the ·collection site were recorded. Drawings were made using camera lucida.

RESULTS AND DISCUSSION

(A) Tylosurus strongylurus (Van Hasselt)

7mm postlar-va (Fig.l) : The body is elongate as in -the case

~~&'~·.·.,~j t------i~----1 2 .

of hemiramphid larvae. The lower jaw is somewhat longer than the upper. The larval finfold is restricted to the preanal part, betow the level of the al.imentary canal region. Fin rays are feebly visible in the dorsal and anal fins. There are 5 rows of stellate melanophores on the body. Melanophores are also present POST LARVAL STAGES OF THE -FISH 371 along the ventrolateral region of the anterior abdomen, on the opercle and on the dorsal part of the upper jaw. The teeth are very prominent on both the jaws. Rows of head serrations are seen just above and below the orbits, on the periphery of the opercle and along the lower margin of the lower jaw.

10.5 mm postlarva (Fig.2): Besides the chromatophores met with in the previous stage, there is a row of melanophores along the midlateral aspect of the body and a few pigments along the dorsal aspect of the abdominal region. One more row of head serration is formed at the posterior end of the opercle. The preanal larval finfold is slightly reduced.

17.5 mm postlarva (Fig.3) : Although both the jaws are elongate, the lower jaw is longer than the upper jaw, and together the 'beak'. There are 5 groups of prominent and countable head serrations on the ventral side of the head beginning from the tip of the lower jaw to the posterior part of the , and 2 groups of serrations on the dorsal side of head just above the orbit. The distribution of the dorsal groups is as below: the first group on the isthmus region has 8 serrations; the 2nd on the periphery cif the operculum has 11 serrations; the 3rd just below the eyes has 8 serrations; the 4th on the lower jaw base has 7 serrations; and, the 5th. on the anterior part of the lower jaw has about 3 serrations. The distribution of the ventral groups is as below: the lst row just behind the orbit has 8 serr­ ations and the 2nd row above the orbit has about 28 serrations. The canine teeth protrude outside. The preanal ~infold has been replaced _by the primordial pelvic fin. The chrornatophores have spread all over the body including the alimentary canal region, but excepting the fin ·rays.

Early larval stages of T. strongylurus closely resemble those of Hyporhamphus limbatus and Pranesus pinguis (ThangaraJa,1982). However they can be differentiated from P. pinguis by the pre­ sence of ventrolateral pigments in the anterior abdominal region, the presence of 3 head pigments on the operculum and lower jaw and the presence of elongate alimentary canal as in clupeids. In the case of P. pinguis, the alimentary canal is very short, eventhough the body is elongate. T. strongylurus larvae can be diff­ erentiated from H. limbatus larvae by the presence of opercular serrations, the elongation of both jaws in advanced stages and the presence of canine teeth in both jaws.

Adult stages are common in the coastal waters, estuaries and backwaters of Porto. Novo. Although it does not grow big, it is preferred as a food fish by the local people. .,. j') THANGARJA

(B) Sphyr·aena jello Cuvier·

18 mm postlarva (Fig.4) : The body is elongate with enlarged jaws, the lower jaws being longer than the upper jaw. Canine teeth are present on both jaws. Two rows of opercular serrations are seen: the 1st row of 2 serrations is just below the orbit, and the 2nd row of 7 serrations just behind the 1st row. Minute pigment dots and stellate pigments develop on the dorsal side of the head and on the operculum just in front of the pee toral base. There are numerous pigments along the alimentary canal region, from the anus to the caudal peduncle, along the region and the dorsolateral side of the body. The midlateral line pigments extend from the caudal penducle to the anal region while the dorsolateral pigments extend upto the 1st dorsal origin. Branchiostegal rays have developed. Fin rays and spines are discernible. The two dorsal fins .are widely separated from each other. The 1st dorsal is of 5 spines and the z,,tj· of 1 spine and 9 r·ays. The position of the pelvic is .below thel~vel oJ the first dorsal. The a,riu·s is located below the level ot' the 2nd dorsal origin.

22.5 mm postlar'va (Fig.5) : The two rows of ·opercular serra­ tions have disappeared. The jaws are of equal length and the teeth are prominent. The extension of the maxillary bone is quite distinct. The chromatophores are numerous. Along the ventrolateral aspect of the body from the caudal peduncle to the ventral margin of the upper jaw , stellate pigments are uniformly distributed; along the dorsolateral aspecc, the chromato­ phores ex tend from the caudal peduncle to the dorsal margin of the upper jaw. Along the course of thA dorsolateral pigments, the pigments are much denser in 6 regions which include the caudal penduncle below the 2nd dorsal, below the lst dorsal and the cranium.

The presence of 5 spines on the 1st dorsal, wide gap between the 1st and 2nd dorsal and the position of anal oppo"site to thAt of the 2nd dorsal origin form the distinguishing characteristics of the larvae belonging to the family Sphyraenidae. On the basis of the origin of the lst dorsal at the level anterior to the tip of pectorals, the position of ventrals below the middle level pf pectorals and the presence of 2 anal spines, the larvae are identified as that of S. jellow and distinguished from S. obtusata, both occurring along the Porto Novo coast.

The larvae were found to be comparatively less active. They rest in a vertical position with the 'beak' pointing upwards and the caudal end downwards. The 18 mm postlarva closely POST LARVAL STAGES Of THE GAR-FISH .373 resembles the 17.5 mm postlarva of Tylosurus strongylurus, but di.f,.. fers from it with respect to the number of dorsal" fin and the position of the pelvic. T. crocodilus has only one and its pelvic is far backwards, close to the anus.

During the period of intensive collection for 24 months (Thangaraj a, 1982 ), the larvae of T. strbngylurus and S. jellow were met with in the plankton samples on one accasion only. The larvae were collected together in ·November 1979 where the salinity and temperature were 17.07°/00 and. 29.38°C respectively.

ACKNOWLEDGEMENTS

The author expresses his sincere thanks: to Or. K. Rama­ moorthi, Retired Professor, and Or. R. Natarajan, Professor, CAS in Marine Biology, parangipettai for providing facilities; to Dr. M. Oevaraj, Professor of Fisheries Biology, CIFE, Bombay for critically reviewing the manuscript; 'to the University Grants Commission for the financial aid and the authorities of Annamalai University for providing all the facilities.

REFERENCES

Bal·, O.V. and L.B. Pradhan, 1945. First progress report on "Invest­ igation of fish eggs and fish larvae from Bombay w.aters", 1944-'55. Govt. Central Press, Bombay.

Bal, D. V. and L.B. Pradhan, 1946. Second progress report on "lnvestigation of fish eggs and fish larvae from Bombay waters;' 1945-'46. Govt. Central Press, Bomb.ay.

Sal, D. V. and L.B. Pradhan, 194 7. Third progress report on "Invest­ igation of fish eggs and fish larvae from Bombay waters", 1946-'47. Govt. Central Press, Bombay.

Bal, 0. V. and L .B. Pradhan, 1951. Occurrence of fish larvae and post-larvae in Bombay waters during 1944-'47. J. Univ. Bombay, New Ser ., 20 B: 15pp.

Basheeruddin, S. and K.N. Nayar, 1962. A preliminary study of the juvenile of the coastal waters off Madras· City. Indian J. Fish., 8: 169-188.

Job, T .J. and S. Jones, 1938. Studies on the development of

the Indian gar fish, Tylosurus strongylurus (Van Hass.)9 with THANGARJA

notes on the young stages of Hemirhamphus gaimardi C uv. e t.

Val. Rec. Ind. Mus. 9 40: 245-253.

Nair9 R.V., 1952. Studies on some postlarval fishes of Madras plankton. Proc. Indian Acad. Sci., 35 B: 225-244.

Thangaraja, M., 1982. Studies on development, distribution abundance of fish eggs and larvae in the Vellar estuary, Porto Novo {South India). Ph.D. Thesis, Annamalai University. 265 pp.

Venkataramanujam, K. 1975. Studies in fish eggs and larvae of Porto Novo coastal waters. Ph.D. Thesis,. Annamalai

University 9 293 pp.