The physical effects of an acoustic tag on the swimming performance of plaice and cod
Drag measurements in a small flume show that the Mitson-West transponding acoustic tag developed at the Fisheries Laboratory, Lowestoft, has a frontal drag coefficient C D 0 = 0·6. For fish moving at constant speed the ratio of fish drag to tag drag is given by D/d = 0·82 L 2 C D , where C D is an a...
| Published in: | ICES Journal of Marine Science |
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| Main Authors: | , |
| Format: | Text |
| Language: | English |
| Published: |
Oxford University Press
1978
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| Subjects: | |
| Online Access: | http://icesjms.oxfordjournals.org/cgi/content/short/38/2/189 https://doi.org/10.1093/icesjms/38.2.189 |
| Summary: | Drag measurements in a small flume show that the Mitson-West transponding acoustic tag developed at the Fisheries Laboratory, Lowestoft, has a frontal drag coefficient C D 0 = 0·6. For fish moving at constant speed the ratio of fish drag to tag drag is given by D/d = 0·82 L 2 C D , where C D is an appropriate drag coefficient for the fish and L its length in cm. Acoustically tagged plaice, Pleuronectes platessa (36–52 cm length), and cod, Gadus morhua (50–70 cm length), tracked by sector-scanning sonar in the southern North Sea have been observed to swim at speed of 1 to 2 L S−1 through the water. Calculations with theoretical and experimental values of C D show that the smallest of these fish could have been slowed down by 7% and the majority by rather less than 5%. The extra ower output required for a tagged fish to maintain the same steady speed as an untagged fish is between 3% and 5% and to maintain the same constant rate of acceleration less than 1%. The results suggest that the swimming performance of plaice and cod observed by sector-scanning sonar is unlikely to have been affected in any significant way by the addition of the acoustic tag. |
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