ACCLIMATION STATES OF JUVENILE STRIPED BASS 707 



TABLE 1 



ACCLIMATION STATES OF JUVENILE STRIPED BASS, 



Morone saxatilis (DEC. 5, 1975), HELD IN CONSTANT AND 



FLUCTUATING REGIMES* 



*One fluctuation was with temperature rising (+) and the other was with 

 temperature falling (— ) between 0600 and 1800 hr. Fluctuations were for 24-hr 

 periods, with a sinusoidal curve ±5 C around a 20 C base. Acclimation states 

 were compared by determining critical thermal maximum (CTMax) expressed as 

 degrees centigrade. CTMax heating rate was 1.5 C/min, and the end point was 

 permanent loss of equilibrium. 



tDuncan's new multiple range test identified differences in these mean 

 CTMax values. Any two means not underscored by the same line are 

 significantly different (P < 0.05). 



series were different (P < 0.05). Test time did not affect CTM 

 (ANOVA P < 0.75) (see Table 2). 



The acclimation response of young-of-the-year striped bass in 

 fluctuating temperatures fell between the mean (20°C) and maxi- 

 mum (25°C) temperatures of the fluctuation. There were no 

 significant differences, however, between CTMax 's obtained for fish 

 tested when temperatures were rising and falling during the period of 

 illumination. The CTMax values determined increased with the 

 frequency of exposure to higher temperatures (Fig. 3). 



DISCUSSION 



The results of this study differ from those of several previous 

 investigations. Brett (1944) determined that a warm water catfish 



