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Examples of Telemetry and Video DataOver the past few years we have obtained a considerable amount of telemetry and video data from cod in the net pen. Below are some examples and some preliminary conclusions. Individual Fish Tracking We now have a total of ~50 billion data points, collected during 1718 hours tracking 48 different fish. Once the data is processed, we can visualize the movements of individual fish in several different ways. To the left is a video, in both AVI and MOV formats, showing the movements of one fish during a period of time when food is being administered through a feeding tube located near the top of the pen. Superimposed on that video is a video shot using a camera located at the bottom of the cage. It shows the behavior of many of the other fish, as they swim up to feed. Data of this type can be used to determine how often fish feed and whether they feed during the entire time feed is provided each day. One clear finding from this work so far is that cod are most active in the day. They also show spikes of increased swimming velocity during bouts of feeding. The cod in this study swam at an average speed of 23.13 cm/sec (0.74 BL/sec).
One might think that fish is a large pen would swim around and around in circles. However, our data do not support that hypothesis. Rather, they spend different parts of the day in specific areas of the cage. The video to the left is a density plot of the area occupied by a single cod during 24, 1 hour blocks of time. Note how it is more active during the day than the night and how it rises to the top of the cage during feeding. |
One of the major advantages of telemetry in comparison to video data
is that telemetry data can be easily quantified. Thus, it is simple
to calculate the average swimming speed of cod in the net pen, over
whatever periods we desire.
