C. Centre Island.

Records from this area have been made under such different circumstances from those at Tory Channel and Whangamumu that it is not feasible to compare the numbers closely with those recorded at the latter localities. No continuous watch was kept and the lighthouse keepers were not trained whale observers. In spite of these handicaps, the number of whales reported by them was so large, as compared with elsewhere along the New Zealand coast, and the records were kept for a sufficiently long period (four years), to give useful indications of the seasons for humpback movements past the south-west part of New Zealand.

During four seasons the northward migrants were first seen near Centre Island on or about May 10 and continued steadily until mid-July, when a decrease in numbers per day occurred and lone whales only were seen until these had also passed the area by early August. The mid point for 218 whales recorded during these months was June 15.

South-bound humpbacks, during the same four years, were first recorded between October 2 and October 6, but did not occur as a steady stream until approximately October 20. From that date until late November the greater part of the sightings were made, and except for “stragglers” the last humpbacks were sighted between December 9 and 14. Approximately 1,500 humpbacks were recorded for these months in four years, and the date on which half the sightings had been completed was November 8. The 300 counted in six days during November, 1955, are not included because the observations made at that time covered too short a period to indicate the duration and scale of movement in that year.

The most striking feature of the humpback migration past this area is the great difference in the numbers passing when north-bound as compared with the numbers passing when south-bound. From Fig. 5 it can be seen that although the period during which north-bound humpbacks are observed near Centre Island is longer than that for south-bound whales, approximately seven times as many have been recorded in the latter period as in the former. Part of this apparent increase may be caused by the re-counting of whales which remain relatively stationary in the area for several days as described earlier. However, the large totals frequently recorded in separated groups on any one day are also much greater than any noted during the north-bound migration, and it is evident that considerably more humpbacks traverse the locality when south-bound than is the case when north-bound. It may be largely the resut of a cumulative effect from whales approaching the west coast at various points and then all being deflected into the same area by the southwest trend of the coast.

The likelihood of such a cumulative process during the northward migration along the east coast of New Zealand has been discussed, and it was also pointed out that a considerable proportion of the humpbacks pass through Cook Strait and others may leave the coast beyond East Cape. Consequently those sighted near the northern end or any other part of New Zealand represent only a portion of the stock which approach the whole east coast of New Zealand. Of the south-bound whales reaching the west coast of New Zealand, only a negligible proportion pass through Cook Strait and there is no headland comparable with East Cape from which humpbacks leave the west coast until the south-west corner of the South Island is reached. Therefore the humpbacks seen in the latter area represent almost the entire accumulation along the west coast of both islands of New Zealand, whereas the much smaller