WHITEBAIT EGGS

Hokitika Guardian, 27 March 1930, Page 2

WHITEBAIT EGGS

IMPORTANT BIOLOGICAL DISCOVERY. ( 1 ‘Manawatu Standard.”) FOXTON, March, 20. A discovery which may play a most important part in the iuture of the whitebait industry of this Dominion, was made by Captain L. Hayes M.C., of the Marine Department, on Monday. Last month Captain Hayes spent some time here when he made a comprehensive survey of the various waterways and lagoons with a view to securing some of the larger species of inanga (the parent fish of the whitebait) which he anticipated would “run* when the drain connecting Robinson’s lakes with the sea was opened. Unfortunately the “run’’ did not take place, but, nevertheless, the captain secured a number of samples and other useful data prior to his return to Wellington. It was with the object of further prosecuting his research work that he returned to Foxton last week and on Monday his efforts were rewarded for at a point a mile or so below the Foxton wharf he located the parent fish actually in the act of spawning. During his previous visit Captain Hayes explored a small drain on the northern bank of tjie Manawatu River at a spot known to’fishermen as Raupo, where he found low lying rush covered mud fiats which at the time he considered a very likely breeding ground for the inanga. .

Captain Hayes arrived at Raupo an hour before hjgli water and, by means of a set net - placed in the drain for possible down-coming fish meeting the tide, large numbers of inanga were netted when it was immediately seen that a “run” down, of inanga was taking place and the fish were liberated without the necessity for handling. The movements of the fish were then closely observed at the mouth of the clpain .when, they were seen to he passing' through the rushes, towards highwater mark.'' ’!•' A careful watch was ip ain't allied 'in the brief space of time tljat. existfj. between the maximum flood tide and the'commencement of the ebb. Captain:Hayes’ was. a lone spectator of a most remarkable sight for, before his Very eyes,:'.the water which covered the low rush flat turned milky white. Carefully. parting the weeds, he gazed for the first , time on the spawning of the inanga and,. as r the tide receded, leaving in itjs. wake millions of whitebait eggs, lie was 1 able without much difficulty to secure some excellent samples. On the following day an invitation was extended to a “Standard” representative to visit the spot on the chance that spawning would again take place at high water that day. Raupo was reached just at flood time. A few seconds later Captain Hayes announced the fact that spawning was going on all over the flat on which they stood. When the water had completely left the area,, a closer investigation was possible and everywhere could be seen whitebait eggs. The floor was covered with millions of eggs which were also to be seen adhering to the rushes and weeds, but all carefully covered with a thick matting of vegetation which completely shielded them from the wind and the ravs of the sun and kept them in a damn humid atmosphere ranging fi’nrri P 9 degrees Fall, to 72 degrees Foil., ideal for incubation purposes. The strangest part of the whole discovery however, was that the fish d°pnU+.nrl their chiefly at the limit of high water with the result that the first official discovery of whitebait e"gs was made hv Captain. Haves on the roots and stems of a clump ef clover, tho last place one would think to °o->reh for tlve eggs of this elusive little fish.

In conversation with the “Standard” representative, Captain Hayes said that the actual thing which led to the discovery was his knowledge of the behav'ou common to spawning fish. When he reached Raupo on Monday he knew that fish were spawning near at hand by their behaviour and the noise emanating from the rush covered flat. He could not see what was going on there at the time, hut knew the noise was that of the convulsions of spawning fish. His first move was to ascertain if the spawning fish were inanga and lie made a trap and caught some of the fish which confirmed this fact. The Water then became discoloured and he knew that lie had been successful in locating the spawning ground of the inanga. From the fact that he had discovered the eggs of the inanga to lie highly adhesive and heavier than salt water as a result of last year’s investigations, when he stripped eggs from a female fish and successful bred them in captivity in Wellington, lie anticipated that he would he able to locate some eggs when the tide receded, as there was scarcely any movement in the water there, the tide merely creeping over the area.. A spot was accordingly m a'deed during the height of spawning and* at the first parting of the grass when the water receded Captain Hayes recognised at once small translucent spherical eggs exactly the same as those hatched last year. A closer examination with a powerful hand lens established without doubt that they were those of the galaxias attenuntus, the parent of the young fish commonlv known as whitebait.

. A great deal of time will have to ho spent to thoroughly round off the observations, said Captain Hayes, but these final observations are not of any particular economical importance. For instance, it is impossible to say at the present whether one pair of inanga mate and keen together all the time. That would take a long time to decide and

there are many other matters which come into the academic side of the in vestigation which docs not enter int the functions of the department. Fron the observations carried out on tin two spawning days, it appeared quiti feasible that the females moved about fairly freely, and deposited eggs in the milt” of different males. It was not kiimfp how many days in which spawn ing was carried on, lnit the time lasted only for about half an hour, immediately before liiglnvater. On Monday spawning occurred to a far greater extent than it did on Tuesday, the whole area, a Strip of ground three yards wide by- two chains in extent being wholly discoloured by the milt. The department had a definite record as a result of last years investigations that the inanga ran to spawn from February 10th to Mnv 19th, and that tlmre were two definite age groups'hut what the age groans comprised they did not knew. Tim first spawners however, were the larger fish, the smalle-- running in April and May. Mr Jack MeOregor, however, had known th.e fish to spawn in January, Mr Jack McGregor, said Captain Haves, was the first man lie had come in contact with who could show him a place where lie had actually seen inanga spawning. That had been in a drain on Matakarapa opposite Robinson’s Bend which was only flooded at high tide. Mr McGregor had been of the greatest assistance to him and displayed keen interest in the investigations. <

Fortunately, said Captain Hayes, 1 have not noticed anything in the ground which might eat the whitebait eggs. Birds, strange to sny, have been very scarce ip the locality hut unfortunately it appears as if cattle do an immense amount of damage to the eggs. One hoof mark would be sufficient to wipe out thousands of the eggs, while it appeared as if a herd of cattle could wreck a whole bed of spawn.

Questioned as to how long he had been engaged oi research work in connection with the whitebait, Captain F°v»s said that tin's was his third official visit to Foxton in that connection over a period of two years. Last year he had', stripped four, pairs of; pi-

anga on May 19th, the largest being hree and' a-lialf inches long, and had ,oen able to establish the density of the ggs the period necessary for incuba,ion and the required temperature. He ,ad discovered that the eggs hatched •)ut quite well in fresh water at a temperature of 65 degrees, but possibly die mud fiats when the tide was out would show a greater temperature than this. The eggs were from 1.25 to 1.3 millimetres in size and were pale yellowish translucent spheres. Questioned as to bow it was young whitebait were so often to he seen coming over the bar and entering the Manawatu R : ver in the season. Captain Hayes said that he could not explain that ex oept to say that it had been discovered (bat quinnat salmon proceeded 150., miles up the Frazer River in Canada to spawn, and that young fish after being hatched out gradually worked their wav down that 1590 miles to the sea. There was a possibility that some whitebait were swept out to sea during the earlier stages of their lives and returned to the rivers in the season. The discovery of the spawning ground six miles up the river seemed to be quite conclusive evidence, that the inanga did not spawn at sea.