NOTE Benetti et al.: Growth rates of captive Coryphaena hippurus 



153 



Results are expressed as: 



Absolute growth 

 Absolute growth 



rate 

 Relative growth 

 Relative growth rate 



Instantaneous growth 



rate 

 Specific growth rate 



Length-weight 

 relationship 

 VGBM (length) 

 VGBM (weight) 



AG = W 2 - Wj 



AGR = (W 2 -W 1 )/(t 2 -t 1 ) 

 RG = (W 2 -W 1 )/W 1 

 RGR = (W 2 -W i )/W 1 

 (t 2 ~t 1 ) 



IGR = (In W 2 - In W x ) / 

 (t 2 - tj) 



SGR = (In W 2 - In W x ) / 

 {t 2 -t 1 )x 100 



W = aL b 

 L. = L (1 



-Kit-t 



; o>) 



W, = W (l-e- /f,( - < o ) ) b , 



where W r = initial wet weight offish; W 2 = final wet 

 weight offish; t x = time at the beginning of an inter- 

 val; t 2 = time at the end of an interval; L = fork length 

 in cm; a and b are constants; L ( = fork length (cm) at 

 time t; W t = total weight (kg) at time t; L m and W m = 

 theoretical asymptotic length and weight, respec- 

 tively; K = constant indicating the rate of change in 

 length and weight (the Brody growth coefficient); t- 

 time; t = time of hatching; and VBGM is the von 

 Bertalanffy growth model (Ricker, 1975, 1979; von 

 Bertalanffy, 1962; Fabens, 1965): 



Results 



Fish grew to 4.93 kg and 75.8 cm from hatching in 

 9.5 months. Absolute growth rates (AGR's) in weight 

 and length were 19.18 g-d -1 and 0.227 cmd -1 , respec- 

 tively (Table 1). Specific growth rate (SGR) of 1-3 

 month juveniles was 10% of their body weight per 

 day, decreasing to 4.3% throughout the adult stage. 

 Most of the data correspond to fish younger than 6 

 months. The calculation of separate growth curves 

 for males and females was not legitimate because 

 sexual dimorphism could not be detected before that 

 age. Therefore, the growth curves and the von 

 Bertalanffy growth parameters were calculated from 

 combined data for all male and female fish. Growth 

 in length of dolphin was best expressed by a linear 

 relationship (r 2 =0.98), though an asymptotic curve 

 also fit the data well (r 2 =0.90). From Figure 1 it ap- 

 pears that a linear fit is better because of a weight- 

 ing of the regression by the smaller fish. Growth in 

 weight was best expressed as a quadratic equation 

 (r 2 =0.98, Fig. 2). The length-weight relationship is 

 expressed by the equation 



W = 0.00836 L 307 (r 2 =0.98; Fig. 3). 



The von Bertalanffy growth models (VBGM) were 

 used to estimate dolphin growth beyond the scope of 

 data measured and, therefore, should be interpreted 



