consumption in microliters from hatching 

 through and beyond metamorphosis on dry body 

 weight were nonlinear and fitted best by a third- 

 degree polynomial (Figure 5 from Laurence 1975). 

 A third-degree polynomial was statistically most 

 significant, as indicated by analysis of variance 

 (F = 13.2 for cubic term, 7.4 for quadratic term, 

 and 9.5 for linear term) over the weight range 

 studied (10-4,000 /xg). However, in this research 

 the size range for larvae was 10-1,000 /xg, and 

 only the predicted data from the first ascending 

 leg of the polynomial at 8°C were used in the 

 computations. 



2-C 2 -0 451  6 » id'w - IJ « ld*W 2 + 15 .lO^W 5 



5*C 0, = 0601  33 x 10 W-l 7x 10 W »2 5 i 10 W 



'^.-> c . ,^»,„> 



DRY WEIGHT (ug) 



FIGURE 5. — Regression of mean hourly oxygen consumption on 

 dry weight of winter flounder larvae and juveniles at three 

 temperatures. Circled data points indicate metamorphosed 

 juveniles. Results at 8°C used in these studies. (From Laurence 

 1975.) 



FISHERY BULLETIN: VOL. 75, NO. 3 



BIOENERGETIC MODEL 



A general model for the transformation of food 

 to fish flesh and the energy relationships involved 

 has been discussed in detail by Winburg (1956) 

 and Warren and Davis ( 1967). The basic relation- 

 ship can be expressed as: 



Q + =Q +Q' +Q 



(1) 



where Q + = energy of food consumed 



Q* = energy of waste products in feces and 



urine 

 Q' = energy of growth 

 Q_ = energy of metabolism. 



Since a portion of the energy value of food is 

 lost in the feces and urine and not utilized or 

 assimilated, Winburg (1956) proposed the follow- 

 ing "balanced equation": 



where b = the coefficient of utilization or, in 

 Brody's (1945) terminology, the physiological 

 useful ration. Equation (3) analyzes the conver- 

 sion of food energy inside the fish (physiological). 

 However, influences of the environment on food 

 consumption and utilization must also be consid- 

 ered. Many modifications based on my experimen- 

 tal results and additions of methods of other 

 researchers have been incorporated into a model 

 suitable for a broader analysis of the bioenergetics 

 of winter flounder larvae. The following para- 

 graphs present a detailed description of the 

 methods used to derive this model. 



Ivlev (1961b) formulated a model founded on 

 the basic bioenergetic equation (Equation (3)) for 

 the utilization of food by plankton-eating fishes. 

 The relationship is: 



0.7Q + = Q' + Q 



(4) 



The coefficient of utilization (b) is assumed to 

 be 0.7, based on information provided by Ware 

 (1975) who reviewed the most recent thinking of 

 the efficiency of food conversion. During the 

 course of a day, a larval fish will be active in 

 daylight (while feeding) and relatively passive the 

 remainder of the time (usually at night). It can 

 be assumed that the intensity of metabolism dur- 



534 



