| POTENTIAL INDICES FOR ESTIMATING NUTRITIONAL CONDITION AND GROWTH RATES OF JUVENILE ATLANTIC COD (GADUS MORHUA) |
| CALDARONE, E.M. and MacLean, S.A., NOAA/NMFS, 28 Tarzwell Dr., Narragansett, RI, USA, 02882, elaine.caldarone@noaa.gov, sharon.maclean@noaa.gov; Sharack, B., NOAA/NMFS, 74 McGruder Road, Highlands, NJ, USA, 07732, beth.sharack@noaa.gov |
| We conducted a 23-day laboratory study to evaluate the response time and efficacy of a suite of potential indices for estimating nutritional condition and growth rates of juvenile Atlantic cod (Gadus morhua) (16 - 24 cm TL). The indices evaluated were: whole body bioelectrical impedance analysis (BIA), white muscle nucleic acid ratios (RNA/DNA), and whole-body proximate composition (total fat, protein, ash and water content). To obtain a range of nutritional condition and growth rates, individually tagged fish were subdivided into two groups: one fed (ad libitum) and one not fed. From each group, 4–5 fish were sacrificed every 3–4 days. For each fish, BIA measurements and tissue samples (RNA/DNA) were taken, and proximate composition was determined. By day 7 of the study, fish in the two groups exhibited significantly different growth rates. Differences between the groups were detected in mean RNA/DNA values by day 11, mean condition factor (Fulton’s K) by day 19, and mean phase angle values (BIA) on day 23. Mean proximate composition did not differ between the groups on any sampling date. Although the mean growth rate of the fed fish was low (0.3% mass day-1), RNA/DNA values were significantly correlated with growth rate (r = 0.70). Of the indices evaluated, RNA/DNA was the first to respond to food deprivation and the only one demonstrating the capability to estimate growth rates in juvenile cod. |
| back |
|
