WHITEBAIT

Southland Times, Issue 21650, 11 March 1932, Page 2

WHITEBAIT

LIFE HISTORY THEIR SPAWNING HABITS. CO-OPERATION IN RESEARCH. While most people would b£ ready to agree that whitebait are greatly valued as food, few people know anything of the. life history of these little fish. In the course of an interview with a Times representative Mr George Jaquiery, secretary of the Research- Committee of the Southland Acclimatization Society, outlined what had been accomplished by the Marine Department as the outcome of its investigations in northern parts of New Zealand and made an appeal to local fishermen and those interested in nature generally to further the cause 'of research into the life history of whitebait in Southland. “Whitebait have been diminishing to such an extent as to give cause for concern,” said Mr Jaquiery. “It is believed that factors apart from the catching of the fish arc to blame for the scarcity. One of these factors is the destruction of the spawning beds by cattle or other agencies. I hope that with the assistance of other observers more light will shortly be thrown on this fascinating problem.” Mr Jaquiery handed to the reporter circulars from the Marine Department detailing the facts so fur ascertained concerning the spawning of whitebait, together with information intended to enable those who are interested to observe for themselves the act of spawning and to locate spawning grounds which have not hitherto been discovered. The following arc extracts from the circulars: — “All other fish known in New Zealand spawn in the water. The eggs of most sea fish float in the sea, some are attached to weeds or to stones, while salmon and trout bury their eggs in shingle on the bottom of the stream. Whitebait eggs are deposited so that they are out of the water from within an hour of being laid till the time the young ones hatch out. That is the remarkable and highly important fact about the propagation of this species.- The parent fish (or inanga) achieve this by making use of the spring tides, when the water comes up over the beach or the bank of a tidal river higher than usual. From tho highest spring tide, which usually occurs at full or new moon, or a day or two later, the high water mark becomes lower and lower until the time of quarter or threequarter moon when the lowest levels for high water mark are reached. These are the neap tides. It is clear from the above that during a spring tide a fish could get to places which would actually be dry land during the neap tide periods. It is well-known to Maoris that at the time of spring tides in late summer and autumn the inanga come down to the tidal waters near the mouths of rivers and creeks and there spawn. The Maoris apparently were under the impression that the spawn was washed out to sea where it produced whitebait which eventually came back to the river. From observations made during the list two years it has been found that natural spawning has taken place during November, December, January, February, March, April and May. In the tidal portions of whitebait creeks or rivers the parent fish may be seen to congregate m schools which number from a dozen to many hundreds about the time of the highest spring tide; and spawning actually takes place either on the highest tide or, more usually, on the tide following the highest of the “springs” of that particular moon. Where Spawning Takes Place.

The spawning beds will be found on the banks of the tidal portion of the river where the ground is covered at high water time of the Highest, or nearly the highest, of the spring tides and is left uncovered even at high water when the spring tide “takes off.” The places chosen by the parent fish must be accessible and must afford cover for the spawn. Bare ground, or ground which is covered only by short grass, is unsuitable and will not be used. Fairly long thickly growing grasses and rushes or similar vegetation which is partly submerged in water at spring tides has been found to be the sort of spawning bed usually chosen. The ground of a spawning l>ed >s firm and clean and free from silt or mulch. The water may be almost salt or may be practically fresh river water backed up by the push of the flood tide. Under favourable conditions the schools of inanga ready to spawn may be seen cruising about near the water’s edge at about the lime of high water. As soon as it has reached its highest level, but not before, and usually some minutes or possibly as much as an hour after high water, the fish make their way among the herbage, swimming or wriggling in the inch or two of water covering the ground. The eggs arc deposited on the ground and about the bases of the stems of grasses and at the same moment are fertilized by the milt exuded by the males. Sometimes a slight spattering or flicking sound may be heard, caused by the movements of the fish; and if spawning is taking place to any considerable extent the water which drains oil as the tide goes down may be seen to bo milky white from the presence of the milt. The eggs have the appearance of tiny balls of clear or slightly yellowish jelly about the size of a pin's head. Since the lime and place are so chosen that when the tide has ebbed the place will not again be under water till the next spring tides reach a sufficient height to cover the eggs, it is obvious that this pccu liar spawning habit provides a piace of safety from the attacks of all luatic enemies such as cels, bullies or l ayfish which would find the spawn very desirable food. When the eggs are next covered, which will be at the least nearly a fort night later, the young ones hatch out and are carried away by the ebb tide, to grow to the whitebait stage in salt water. By this unique device and by thus making use of the extensive areas of suitable land which under natural conditions were to lx found on the banks of the tidal reaches of most of the New Zealand streams it was possible for the species to propagate itself under conditions which were extremely favourable to the survival of a large proportion of each new generation. This undoubtedly accounts for the enormous abundance of whitebait in the early days of the colony. Civilization and settlement have brought about considerable changes, to the great detriment of the whitebait. Place? which nature made suitable mad safe for spawn are now grazed and tramp led over by cattle and other stock and arc affected in various ways by human operations resulting in an enormous amount of damage and loss to the spawn and consequently to the whitebait supplies. It is therefore of the utmost importance that spawning places should be located in order that steps may be taken to ensure the protection of the spawn from these ravages which, unknown to everyone, have been taking place for years while whitebait- supplies have been getting progressively poorer. Directions to Observers. Observers are advised to equip themselves with a note book, a pencil, a knife, a reliable watch and a rough tide gauge. It is desirable that prior to that period which has been selected to look for the spawning shoals observers should acquaint themselves with the nature of both banks of any creek, stream or river on that portion affected by a regular periodic rise and fall of the level of the water. In Southland the tide runs back as far as Wallacetown. The type of bank most usually selected and regularly used by the spawning shoals arc the low-lying rush and grass covered portions over which the spring tides creep for a distance of anything up to eight yards. On no account should attempts be made to survey large areas of rush flats regularly covered by tho tide and extending far back from a main water channel, as they do not harbour spawning grounds. The spawning usually occurs on dates which coincide with either the two or three successive days immediately following that day when the highest tide occurred. The spawning act will commence at the earliest at the time of high water. If, however, the range of the tide is very considerable, spawning will commence sometime after high water. The spawning act usually lasts about three-quarters

of an hour from the time of commencement. The observations which should be noted are as follows: (1) Give the ground a name and define it as accurately as possible, for example “the patch of rushes at the, bottom of Mr Robinson's paddock adjoining Dunn’s Road.” (2) Describe roughly the ype of beach and vegetation. (3) Whether ;tock at the present time have access to he ground. “I trust,” concluded Mr Jaquiery, “that ishermen and others will co-operatc in tins ■esearch work. \ny information I rceive will be forwarded to the proper quar.er.” ‘