SIZE -FREQUENCY DISTRIBUTION 

 C. [QUISIUS 



I 



N:78 



PI n 



m,nn.,,nmM 



so 90 100 no no 



STANDARD LENGTH (mm) 



Figure 3. — Size-frequency distribution of Coryphaena 

 equiselis which were attracted to the night light and 

 caught in dip net during ATEX aboard the RV Discover- 

 er, February 1969. 



data, I infer that the species spawns in the trop- 

 ical mid-Atlantic during January and February. 



My specimens are presently stored at the Troi)- 

 ical Atlantic Biological Laboratory, Miami, Fla. 



I thank Drs. Bruce B. Collette, Robert H. 

 Gibbs, Jr., and Robert V. Miller for reviewing 

 the manuscript, and Grady W. Reinert for pre- 

 paring the illustrations. 



Literature Cited 



Collette, B. B., R. H. (iiBBS, Jr., and G. E. Clipper. 

 1969. Vertebral numbers and identification of the 

 two species of dolphin (Coryphaena). Copeia 

 1969: 6.30-6.31. 

 Gibbs, R. H., Jr., and B. B. Collette. 



1959. On the identification, distribution, and biology 

 of the dolphins, Coryphae^ia hippuriis and C. equi- 

 selis. Bull. Mar. Sci. Gulf Caribb. 9; 117-152. 



POTTHOFF, T. 



1969. Searching for tuna. Commer. Fish. Rev. 

 31(7): 35-37. 

 Rothschild, B. J. 



1964. Observations on dolphins (Coryphaena spp.) 

 in the central Pacific Ocean. Copeia 1964: 445- 

 447. 

 Stoner, R. B. 



1969. A dryland sailor tries deep sea cruising. 

 Ensign 57(11) : 28-33. 



Thomas Potthoff 



National Marine Fisheries Service 

 Tropical Atlantic Biological Laboratory 

 Miami, Fla. 3311,9 



RESPIRATORY, BEHAVIORIAL, AND 



ENDOCRINE RESPONSES OF A TELEOST 



TO A RESTRICTED ENVIRONMENT 



It is common practice when measuring fish res- 

 ]3iration or activity to allow a varying length of 

 time for the fish to become accustomed to the 

 restrictions imposed by the apparatus and to 

 allow time for any oxygen debt to be repaid 

 (Fry, 1957). The following observations indi- 

 cate that such a procedure may introduce com- 

 plications in the interpretation of results since 

 the acclimation process results in changes in res- 

 piration, behavior, and endocrine activity. 



Poecilla reticulata males were placed in 

 groups of 10 in the 100-ml chamber of a con- 

 tinuous flow respirometer. Animals were main- 

 tained at 25° C with a 12-hr daylength and fed 

 daily at the start of the light period. Measure- 

 ments of oxygen were made with the wide bore 

 dropping mercury electrode (Briggs, Dyke, and 

 Knowles, 1958) or by the micro Winkler method 

 (Fox and Wingfield, 1938). 



A daily cycle of routine respiratory activity 

 in such an apparatus has already been described 

 (Sage, 1968). The minimum of oxygen con- 

 sumption occurs at the end of the dark period 

 23 hr after the last feed and this rate approx- 

 imates to the standard metabolic rate. Measure- 

 ment of this rate at daily intervals indicates a 

 progressive fall in standard o.xygen consumption 

 (Table 1). A similar fall in respiratory rate 



Table 1. — Effect of number of days in respirometer on 

 standard rate of o.xygen consumption of a group of 10 

 fish. 



Days 



Oxygen uptake mmVg/hr 



212 

 156 

 126 

 109 



to a base line of approximately 100 mmVg/hr 

 was observed with four other groups of fish 

 whereas control animals from large containers 



879 



