Scope for Activity, Specific Dynamic Action and Growth in Early Juvenile Stages of Atlantic Cod, Gadus morhua

• Main Author: Hansen, Sorren Lund
• Format: Text
• Language: unknown
• Published: DigitalCommons@UMaine 2003
• Subjects: Atlantic cod growth; Gadus morhua; Animal Sciences; Oceanography; Oceanography and Atmospheric Sciences and Meteorology; atlantic cod
• Online Access: https://digitalcommons.library.umaine.edu/etd/137; https://digitalcommons.library.umaine.edu/context/etd/article/1140/viewcontent/HansenSL2003.pdf

Growth rates of early life stages of Atlantic cod (Gadus morhua) are very high, but decline, as the fish grow larger. Little is know about the physiological processes that facilitate and regulate this growth pattern. In this study, feeding and swimming metabolism were measured in individual juvenile Atlantic cod (Gadus morhua) in order to investigate how energy are allocated to swimming and growth in fast growing stages of fishes. Metabolic rates were measured by the means of oxygen consumption using two "Brett-type" respirometers. The metabolic measurements were repeated several times in individual juvenile Atlantic cod with a wet body mass of 0.5-5.0 g over a period of 100 d. Wet body mass and total length of individual cod were measured biweekly during the experimental period and used together with metabolic measurements to determine the relationship between energy utilization and growth. The study consisted of two parts, 1) determination of aerobic scope for activity (the difference between standard and active metabolism), and 2) measurement of specific dynamic action (SDA, which represents the energy expenditure for ingesting, digesting, absorption of foodstuff, biochemical transformation of nutrients and assimilation of proteins). Power-performance relationships between oxygen consumption and swimming speed were established for juvenile Atlantic cod for the first time. Standard metabolic rate (RJ and active metabolic rate (R) were calculated fiom the power-performance relationships by extrapolating to zero swimming speed and maximum sustained swimming speed, respectively. Scope for activity was calculated as the difference between active and standard metabolism (&-F&). SDA duration, amplitude and magnitude were calculated by measuring oxygen consumption of fed and unfed fish swimming at a low cruising speed. Specific growth rates (G) ranged fiom 1.4 - 4.4% wet body mass dm' and decreased with increasing body mass. Scope for activity ranged fiom 10.2 to 40.7pmol 0 2 h-' for juvenile cod with a mass ...