The goal of this series of of experiments is to estimate how many calories cod use in the UNH offshore aquaculture net pens. We can determine their swimming speed, and patterns of activity, using telemetry. We use respirometry to measure oxygen consumption at different swimming speeds, with representative fish from the same group in the cages, at the same temperature. It is then straightforward to convert oxygen consumption values to calories, and estimate calories burned each day by the fish in the cages.
In the laboratory, using a Brett-type respirometer (shown on left), it is possible to measure the oxygen consumption of cod while they swim at different speeds. These data (liters of oxygen/gram/hr) can then be used to calculate the number of kilocalories they burn in and hour, while swimming at a given speed.
The swimming speeds of 5 cod were measured continuously for 5 days and nights and then we converted swimmming data into calories consumed, as described above. The graph to the left illustrates how fish use more energy during the day than the night ( 40 vs 50 calories/hour).
On average they use ~1000 calories each day.