364 



Fishery Bulletin 90|2). 1992 



In C. arel and C. Ma, age of fish had no effect on 

 the number of eggs. Among fish of the same length, 

 older ones did not contain more eggs than yoimger 

 ones. This resiilt is consistent with the findings of Simp- 

 son (1951) and Bagenal (1957). 



More fecund C. lida (relative fecundity 287-1664, 

 X 988) laid smaller eggs (< 0.6250 mm d.m.), while 

 less fecund C. arel (relative fecundity 124-1096, x 

 464) laid larger eggs (<0.8125mm d.m.). Dahl (1918) 

 and Svardson (1949) also found that more fecund 

 species lay smaller eggs. 



In C. arel and C. lida, males outnumbered females 

 and were relatively smaller in size than females. The 

 present finding is inconsistent with Qasim's (1966) view 

 that the sex which outnumbers the other attains a much 

 bigger size. 



Chi-square values showed a significant deviation 

 from the expected 1 : 1 ratio for 3 months in C. arel and 

 for 5 months in C. lida. Such a deviation could be due 

 to a partial segregation of mature forms through 

 habitat preference (Reynolds 1974), due to migration 

 (Collignon 1960) or behavioral differences between 

 sexes (Polonsky and Tormosova 1969), thus rendering 

 one sex to be more easily caught than another. 



During the present investigation, spent individuals 

 of C. arel and C. lida were not found throughout the 

 study period, since spawning of tonguefishes appears 

 to take place mainly in deeper waters, as observed by 

 Seshappa and Bhimachar (1955) for Malabar sole 

 Cynoglossus semifasciatus. This is a gap in the repro- 

 ductive biology of these tonguefishes. Deep-sea fishing 

 is needed to confirm this type of spawning behavior 

 by the tonguefishes. 



For C. arel, the spawning peak was in January which 

 is the post-(northeast) monsoon period along the south- 

 east coast of India. Monsoonal floods end by this time, 

 and food resources (like copepods and amphipods, 

 which are essential food items of juveniles) are abun- 

 dant; this season would appear to be a favorable time 

 for spawning. The spawning peak of C. lida was in Sep- 

 tember, which is the pre-(northeast) monsoon period 

 along the southeast coast of India; this period coincides 

 with the most active southwest monsoon period along 

 the west coast of India. Most of the rivers originating 

 in the west receive floodwaters through the southwest 

 monsoon and empty them into the Bay of Bengal, which 

 thus gets rich primary food resources at this time. This 

 period would also appear to be a favorable time for 

 spawning, because of food abundance. 



Thus C. arel and C. lida, though co-occurring sym- 

 patrically in the continental shelf waters off Porto 

 Novo, share available food resources and appear to 

 avoid competition for food and space for their juveniles 

 by exhibiting spawning peaks during different periods 

 (pre-/post-northeast monsoon). 



Acknowledgments 



I am indebted to Dr. Bruce B. Collette, Systematics 

 Laboratory, for his many helpful suggestions in the 

 modification of this manuscript for publication, and for 

 providing the facilities of the Systematics Laboratory. 

 My sincere thanks to Dr. Thomas Munroe for critical- 

 ly reviewing part (food and feeding) of the manuscript. 

 Comments made by the editor, and two anonymous 

 reviewers helped in modifying this manuscript. Special 

 thanks go to Ms. Ruth E. Gibbons, for "her suggestions 

 regarding computer graphics. Grateful acknowledge- 

 ment is extended to the University Grants Commission, 

 New Delhi, to Dr. R. Natarajan, and to the authorities 

 of Annamalai University, India, for offering financial 

 support and necessary facilities to carry out this study 

 as a part of my Ph.D. program. I thank Dr. K. Srira- 

 man, Tamil Nadu Fisheries, Porto Novo, for his help 

 in the statistics. My sister, Miss G. Shantha, helped me 

 in processing the data. Computer help extended by Mr. 

 H.A. Kurt Luginbyhl, Dr. Jeffrey Williams, Mr. Tom 

 Orrell, and Mr. Jeffrey Howe is greatly appreciated. 



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