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Whitebait. The results of general inquiries into the condition of the whitebait fisheries were summarized in last year's annual report (pp. 14-18). Arising out of these considerations came the recognition of the fact that until the gaps in our knowledge of the life-history of this species could be filled up we were not in a position to tackle the framing of regulations for its conservation with due insight into the fundamental facts of the situation. In particular, it was recognized that light should be thrown on the spawning of the species. Besides the well-known fact that whitebait, which are inanga {Galaxias attenuatus) at a juvenile stage, enter the mouths of rivers from the sea, there existed convincing evidence that the adults when about to spawn migrated in shoals from fresh water down to tidal water. The Maoris believed that the inanga spawned in the sea, and this view has been accepted by European and New Zealand writers on the subject, although there is also on record an account of the observation of what appeared to be the act of spawning of a shoal of " minnows " close to the bank of the Hokitika Estuary about half a mile from the open sea.* The exact location and identification of the naturally deposited spawn and the distribution of the larval (pre-whitebait) stages were unknown until the Department's investigations were made. Some preliminary light was thrown on the subject when, in May, 1929, ripe inanga of both sexes were obtained from the Whakapuni Drain near Eoxton and the ova artificially fertilized by Captain L. Hayes. Different lots of these ova were kept during the incubation stage in water of four different grades of salinity —(1) Sea-water from Wellington Harbour, (2) a mixture of two parts sea-water and one part fresh water, (3) a mixture of one part sea-water and two parts fresh water, (4) fresh Wellington tap water (derived from the Wainuiomata). The somewhat surprising outcome of this was that healthy larval fishes hatched out from each lot, indicating that both eggs (embryos) and larvae were tolerant to either fresh, brackish, or salt water, which is in itself a very exceptional phenomenon. It suggested that the natural incubation of this species took place under very variable conditions with regard to the salinity of the surrounding water, such as would be found for instance near the mouth of a tidal river. It was also found that the eggs preserved their vitality when kept packed in damp moss for several days. By this experiment also the character of the egg and of the newly hatched larva was determined —a necessary starting-point for the identification of the same when found naturally occurring. The number of eggs produced by a single female inanga has been found to vary from 1,500 in the smallest (2$ in.) fish to over 13,000 in a very large (5| in.) specimen. A further step now to be recorded is the actual observation of the act of spawning, the location of the spawn, the incubation period, the emergence of the newly hatched young fish, and their natural distribution. These observations were carried out by Captain Hayes on the Manawatu River between about three and a half and eight miles from its mouth, on a visit made about the middle of March, 1930, and on subsequent visits. The main facts which he brought to light are as follows : The ripe fish migrate to the tidal water in shoals, arriving at the time of spring tides. These migrations were observed to take place in the Manawatu River this year in March (once) April (twice) and May (twice). There was evidence to support the supposition that a spawning had also taken place in Eebruary. For spawning the shoal approached the very margin of the river at the time of high water. The minute eggs are deposited among rushes, grass, or other vegetation which affords concealment for the spawning fishes and cover for the eggs which adhere in masses on the ground about the bases of the stems of rushes or grasses. Spawning did not take place till the highest of the spring tides had passed. The ova were thus left " high and dry " when the tide receded, and, since they were deposited as near the water's edge as the fish could get and the tides which followed were of diminishing height, there could be no further contact with the water until the next spring tides occurred. The spawn is thus assured complete protection from any aquatic enemy for practically the whole of the incubation period. When the eggs are once more submerged on the next spring tide reaching them, hatching takes place and the larvas are carried down by the ebb tide. At the time when the eggs were hatching out considerable quantities of the larvae were taken by tow-netting in the estuary just above the bar. It has been demonstrated that if the spring tides succeeding the one on which spawning took place are not so high and therefore do not reach the zone where the spawn is deposited, the embryos remain unharmed while hatching is deferred. The period between spawning and hatching may thus be about fourteen days, or it may be extended to as much as forty-eight days. This provision by which the parent fish deposit their spawn at places which are only covered with water at the highest tides practically ensured immunity from enemies under the original natural conditions which held previous to the colonization of New Zealand. Under present-day conditions, however, adverse factors come into play which were not contemplated, so to speak, in the original natural state of affairs. In the locality investigated it was found that horses, cattle, and even human beings, by trampling over the ground on which the whitebait eggs were deposited in hundreds of thousands, wrought a considerable amount of destruction. A full account of these observations and other points connected with the natural history of the whitebait will appear in a later report. It appears that there is a regular " whitebait " fishery carried on from the Northcote pier in Auckland Harbour during the summer months. I was first informed of this fishery by Mr. A. W. Martin, of Northcote, who stated that the run commenced about November and finished about March. He had been catching them at Northcote for the past fifteen years. These facts were so difficult to square with what we knew about the season of the ascent of the Galaxias attenuatus young from the sea that it was suspected that an entirely different species of fish was here involved. Samples of the Waitemata

* Phillipps, W. J. : " The New Zealand Minnow." N.Z. Jour. Boi. &. Tech., Vol. 7, No. 2, p. 117.