Art. XII.—On four Fishes commonly found in the River Avon; with a consideration of the question: “What is Whitebait?”
[Read before the Philosophical Institute of Canterbury, December 2, 1869.]
I Venture to hope that an attempt to settle the vexed question, “What is Whitebait?” will not be unprofitable. The fish, in question, is one of the most important of our fresh-water fishes, and forms a very agreeable variation in our somewhat-restricted colonial diet. A similar question has been raised, from time to time, regarding the English Whitebait, which has been looked upon as the young of the Sprat, the Shad, and the Herring. Naturalists are now, however, tolerably well agreed that it is an adult fish of a distinct species; and it appears amongst the Clupeidæ under the name of Clupea alba. The New Zealand Whitebait has no affinity with the English fish, whose name it bears, not belonging to the same family, even; and the question at issue is this, “Is the Whitebait an adult fish, or the young of some other species? if the latter, what is its adult form?” Attempts have been made to solve the doubt, by keeping Whitebait in confinement, so that they might develope under observation, but these experiments have always been performed without
sufficient care being taken to exclude sources of error. Mr. Johnson, the curator of the Acclimatization Society, has introduced Whitebait into the fishponds in the gardens, and is convinced that they grow and develope into what he designates Smelts. He, yesterday, showed me, in the ponds, a shoal of these fish; they were certainly much larger than average Whitebait, and had somewhat lost their vermiform shape, we could not, however, succeed in catching any of them,—I am glad to say, however, that he captured some this morning; I shall have something to say about them in the sequel. Mr. Bealey also tells me that he put a number of Whitebait into a reservoir supplied only with artesian water, and that they developed into Smelts, and such seems to be the general opinion. Unfortunately, two very distinct fish are confounded together under the name of Smelts, and the observers are not sufficiently positive as to which particular fish the Whitebait became. If, on comparison, the Whitebait should not correspond, in general characters, with any larger fish common in the Avon, we shall be quite justified in rejecting these observations as careless, and inaccurate; if, however, the Whitebait agree closely in generic and specific characters with some larger and common fish, the experiments rise in importance.
This has led me to institute a comparison between the Whitebait and such other fishes as are found commonly in the Avon, with a view to deciding this question, and I now proceed to lay the result of these observations before the Society. I do so, however, with considerable diffidence, partly because I have not hitherto devoted my attention to fishes, and partly because I am almost entirely destitute of works of reference in this particular line, and our libraries are in the same condition; I shall, therefore, endeavour to confine myself to plain and prominent characters, and crave indulgence to any possible errors.
The Whitebait averages two, to two and a half, inches in length; it is anguilliforous in form; and, in its transparency, and the size and prominence of its eyes, has the appearance of an immature fish. It is scaleless, has a transparent greenish tinge, possesses six fins, excluding the caudal fin, which is rather large and forked.
A row of distinct black spots runs along the lateral line. The swimbladder is large and distinct, its situation being bordered by a band of black spots. The teeth are microscopic. The fin rays are all soft, and the abdominal position of the ventral fins refers them to the Malacopterygii abdominales; whilst the single dorsal fin, the absence of scales, and of a spine in the dorsal fin, indicate that it is a Galaxia.
Its specific characters are as follow:—
One dorsal fin; first ribs of dorsal and anal fin in a line, one-third of the length of the body from the origin of the caudal fin; ventral fin abdominal, one-third the length of the body behind the pectorals; teeth, imperceptible; fin rays: (P.) 11 or 12, (V.) 7, (D.) 10, (A.) 16, (C.) 16.
There are only three fish in the River Avon, sufficiently common to justify the supposition that either of them may be the adult form of the Whitebait; these are the Bull-head, the Silver-fish, and the Smelt. The name of Smelt is applied indiscriminately to the two latter fish, we will, however, retain the trivial name of Silver-fish as a distinction. We may first dismiss the Bull-head, there is no possibility of confounding the Whitebait with this fish; it is thoroughly well-known, both in its adult and young form.
It is an Acanthopterygious fish, with two dorsal fins, the first having simple, though flexible rays, it belongs to the sub-class Acanthopterygii, family Gobioïdæ, genus Eleotrinæ, and is probably the Eleotris basalis, described by Dieffenbach; though Dieffenbach's description is too meagre to decide positively. Its characters are as follows:—Head, large, one third the length of the body, which is tapering in form; colour, dark-brown, mottled of a
darker tint, with five blackish bands, transversely covered with a slimy secretion; scales, large and pectinated; gill openings, very wide; gape, small; teeth, microscopic, and densely set; branchiostegal rays, five. No swimbladder; dorsal fins, two in number, large, the first having simple flexible rays; ventrals, distinct, sub-pectoral; anal fin opposite to second dorsal; the fins all banded with black. Fin rays (1st D.) 7, (2nd D.) 10, (P.) 13, (V.) 5, imperfectly developed, (A.) 10, (C.) 15 or 16.
The Silver-fish again belongs to the Malacopterygii abdominales, or fishes having soft fin rays, with the ventral fins placed beneath the abdomen. In its bright silvery colour, it possesses a superficial likeness to the Whitebait, it has, however, no affinity with it.
Everyone will recognize the likeness to the true English Smelt, Osmerus Eperlanus, both in appearance, and in its remarkable smell, when freshly removed from the water, likened, by some to cucumbers, by others to violets; but although it belongs to the same family, the Salmonidæ, it is not a Smelt, as the position of the first dorsal fin indicates, which in the Smelt is situated over the ventrals. The second dorsal adipose, the well-marked cycloid scales, refer the Silver-fish to the Salmonidæ, but to what genus of this numerous and difficult family it belongs, I am quite unable to decide; it has the following characters:
Two dorsal fins, the second adipose and destitute of rays, colour, grey with a silvery band down the sides; belly, white; teeth, small and numerous; branchiostegal rays seven; anal fin slightly in advance of second dorsal.
Fin rays, (P.) 10, (V.) 6, (1st D.) 11, (A.) 17–18, (C.) 18.
We now come to the last fish on our list, called, by boys, the Smelt; but why a Smelt, I know not. And now, even on a superficial examination, we perceive an affinity to the Whitebait, in the absence of scales like the Whitebait; the Smelt is a Galaxia, soft fin rays abdominal, ventrals, a single dorsal, no scales, and the dorsal destitute of a spine. It has a yellowish-brown colour, dotted with black spots, which are especially numerous in the neighbourhood of the lateral line; 1st rib of the anal fin opposite to the third dorsal, and very near the caudal fin; ventrals, half way between gill covers and origin of caudal fin.
Fin rays, (P.) 9 or 10, (V.) 7, (D.) 9, (A.) 15 or 16, (C.) 16.
We will now institute a comparison between the Whitebait and the Smelt.
The fishes from which these notes were taken, were obtained on different occasions, and the characters noted down separately. I have arranged the specific characters in parallel columns, and will give them, seriatim:
|One dorsal fin.||One dorsal fin.|
|Ventrals, one-third length of body behind pectorals.||Ventrals, midway between gill covers and origin of caudal fin.|
|First ribs of dorsal and anal fins on a line, one-third length of body from origin of caudal fin.||First anal rib about opposite to third dorsal and near caudal fin.|
|Fin rays.||Fin rays.|
|P.11||p. 9 or 10|
|A.16||A. 15 or 16|
There is a slight discrepancy in the proportions, but in no respect more than would be expected between a young and an adult fish: the number of
fin rays corresponds almost exactly, and the difficulty of counting the rays in the Whitebait is considerable, as they are more and more rudimentary at the commencement and terminations of the fin. I wish to direct your attention to this drawing of a Whitebait, which has been in the Acclimatization Society's ponds a short time. I think anyone would say it was a young Smelt, it has lost its Eel-like appearance, and is assuming the colour and markings of the adult Smelt.
In concluding this contribution to the natural history of the fresh-water fishes of the River Avon, I may say that I am quite satisfied that the Whitebait is the young of the Galaxia, commonly known as the Smelt, but if any of the members doubt it, let me urge on them the propriety of setting the question at rest in one of two ways; either by developing Smelts from their ova, and observing whether they pass through the Whitebait stage; or, secondly, by preserving the Whitebait themselves and watching their development, care being taken to exclude all sources of error, such as the access of the ova of other fish. Such an experiment is easily tried, and would be decisive.