'Discovery' reports
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By George W. Rayner (Plates V-XXII; Text-fig. i)
The progress and results of whale marking up to December 1939 have been described in a previous report1 wherein is recorded the number of whales effectively marked and the details of the 203 marks then recovered. It was shown from this evidence that the striking feature of whale migration was the manner in which whales of all the three species concerned were found year after year in the same region of the Antarctic as that in which they were marked. This was quite rigidly so in the case of Humpbacks and to a lesser degree with Blue and Fin whales, which are occasionally to be found at more considerable distances from the positions where they were marked. It was also for the first time proved by direct evidence that Humpback whales move from the Antarctic to tropical waters in very definite migrations.
Whaling has only continued on a very subdued scale during most of the war years, but additional marks have been recovered since 1939, all corroborating the results arrived at up to that time. In the case of Fin whales we now possess marks recovered at every yearly interval up to thirteen, and in no instance is the distance between the position of marking and the position of recovery greater than already recorded in the above-mentioned report, which dealt only with marks recovered up to periods of four years. Now that whaling in the Antarctic has recommenced on a considerable scale a greater number of recoveries may be expected in the near future, but until this accrues it is felt that the time has not yet come for a fresh analysis of the data. In the meantime since the previous report gave no more than a rough indication of the distribution of marking (Plate XLV) it is considered useful to publish a detailed record of the positions of markings. These fuller details will substantiate the data already published, and perhaps clarify some of the conclusions reached. The positions of marking show, for instance, the importance of negative results. If whales are marked in various regions over a series of years a certain proportion of recoveries may be expected, and it would be of considerable significance if no marks (or exceptionally few) were recovered from whales marked in substantial numbers in some definite region on a particular occasion. In the same connexion the division of Humpbacks into stocks off Enderby Land and off Queen Mary Land can be considered established; if it were otherwise it is reasonable to conclude, in view of the number of markings off Enderby Land, that whales from both regions would have been taken off North-west Australia.
It is not proposed to draw any new conclusions in this paper, which is intended simply to record positions of marking; but studied in conjunction with the report of 1940 it will be of assistance to those interested in the distribution and migrations of whales.
The positions of marking are now set out in a series of monthly plottings dealing with each of the three important species (Plates V to XXII). Two charts drawn on a polar equidistant projection cover the region from 90° W to 120° E in which whale marking has been carried out (see Text-fig. 1). These charts have been divided into quadrilateral areas bounded by one degree of longitude and thirty minutes of
1 Rayner, G. W., 1940, Whale Marking, Progress and Results to December 1939, Discovery Rep., xix, pp. 245-84.
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