Measurements of the target strength of fish

Reply: The acoustic target strength of fish

“…2 as well as in a more recent paper 4 which takes account of a possible resonance of the .swim-bladder in region (a), whejn n has a value of about 2 (which is in agreement with the experimental results due to Cushing et al).There are also discrepancies inFig. 2of Mr. Carpenter's paper (which was reproduced fromCushing et al) 3. For example, in the Rayleigh scattering region, the vertical separation for a 10/1 change in frequency should be 40dB in view of the A ~ 4 law and the 'knee' occurs at increasingly higher values of the target strength for longer fish.…”

“…5 They suggest that the swim-bladder might be contributing a component of directivity to this relationship. But their fit to data was very much better than ours, 3 and it made it possible to use the reliable dependence of target strength on the length. In our 1963 paper Dr. Haslett's theoretical curve was indeed used but used only to locate the middle zone; the diagrams of target strength vs. log length were in fact based on the data from Midttun and Hoff which were published at that time.…”

“…1 of the first paper is based on my observations which had been published previously, 2 whereas it is drawn from the second paper by Cushing et al 3 (This figure gives the dependence of the acoustic target strength of a fish on its length.) I hope that this note will help to clarify the situation for other workers in this field.…”

The acoustic target strength of fish

“…I should like to comment on the paper by B. R. Carpenter which you recently published 1 and on an earlier paper by D. H. Cushing et al 3 from the same laboratory.…”

“…1 of the first paper is based on my observations which had been published previously, 2 whereas it is drawn from the second paper by Cushing et al 3 (This figure gives the dependence of the acoustic target strength of a fish on its length.) 1 of the first paper is based on my observations which had been published previously, 2 whereas it is drawn from the second paper by Cushing et al 3 (This figure gives the dependence of the acoustic target strength of a fish on its length.)…”