THE VIVIPAROUS-FISH AND ITS YOUNG.
They swim close to the surface in immense shoals, and numbers are very craftily taken by the Indians, who literally frighten the fish into their canoes. At low-tide, when a shoal of fish is in the bay, or up one of those large inlets that intersect the coast-line, the savages get the fish between the bank (or the rocks, as it may be) and the canoe, and then paddle with all their might and main among the terror-stricken fish, lashing the sea with their paddles, and uttering the most fiendish yells. Out leap the fish from the water, in their panic to escape this (to their affrighted senses) terrible monster; and if not ‘out of the fryingpan into the fire,’ it is out of the sea into the canoes—which in the long run I take to be pretty much the same thing.
It appears to be a singular trait in the character of viviparous fish, that of leaping high out of the water on the slightest alarm. I have often seen them jump into my boat when rowing through a shoal, which is certainly most accommodating. The Indians also spear them: they use a long slender haft with four barbed points, arranged in a circle, but bent so as to make them stand at a considerable distance from each other. With this spear they strike into a shoal of fish, and generally impale three or four; many are caught with hooks, but they bite shily, the only baits I have seen taken being salmon-roe nearly putrid, or bits of crab.
Just prior to my leaving Vancouver Island, numbers were netted by some Italian fishermen who had a seine. They found a ready sale for them in the market, but as a table-dainty they are scarcely worth eating; the flesh is insipid, watery, and flabby, and I am convinced that no system of cooking or culinary skill would ever convert it into a palatable fish.
The geographical range of viviparous fish, as far as I have any opportunity of judging, is from the Bay of San Francisco to Sitka. It may perhaps (and I have but little doubt that it does) extend much farther south along the Mexican coast; but this I can only surmise, never having seen them beyond the limits above stated. It frequents all the bays and harbours on the east and west sides of Vancouver Island, and is equally abundant in the Gulf of Georgia and the Straits of Juan de Fuca; making its appearance about the same period, or perhaps somewhat earlier, in the various inlets on the Oregon coast, from Cape Flattery to the Bay of San Francisco. It will be just as well perhaps, before I go into the subject of its specific characters and singular reproductive organs, I should mention how I first stumbled upon the fact of its being viviparous.
Soon after I arrived at Vancouver Island, I at once set to work to investigate, as far as it lay in my power, the habits and periods of migration of the different species of fish periodically visiting the North-west coast. The sole means then at my disposal to obtain fish for examination, or as specimens to send home, was to employ Indians or catch them myself; so it happened, some of these fish were first brought me by Indians. Cutting one down the side (the plan I usually adopt to skin a fish, keeping the opposite side untouched), to my intense surprise, out tumbled a lot of little fish! My wildest dreams had never led me to suppose a fish I then thought was a bream, or one of the perch family, could be viviparous. I at once most hastily arrived at the conclusion that the greedy gourmand had eaten them. Dropping my knife, I sat in a most bewildered state looking at the fish.
The first ray of light that shone in to illumine my mystification seemed to spring from the fact, that each little fish was the model, counterpart, and facsimile of the larger, and in shape, size, and colour were exactly alike: from the position too they occupied in the abdomen of the larger fish, I was led at once to see the error of my first assumption, that they had been swallowed. Carefully dissecting back the walls of the abdomen, I discovered a delicate membranous bag or sac having an attachment to the upper or dorsal region, and doubled upon itself into numerous folds or plaits, and between each of these folds was neatly packed away a little fish; the bag was of a bluish-white colour, and contained fourteen fish. I had no longer any doubt that the fish was viviparous, and that it was a true and normal case of ovarian gestation. So much for my first discovery; the details of my subsequent examinations I shall again have occasion to refer to.
It happened most curiously that a Mr. Jackson (I believe a government officer of the United States) was, about this same period, amusing himself by fishing at Salsalita, and caught two viviparous fish, a male and a female. On cutting open the female, to obtain a piece of the belly for bait, he, like myself, was astonished at seeing a whole bevy of tiny fish come scrambling out, and at first imagined, as I did, that they had been swallowed. He immediately wrote a letter to Professor Agassiz, sending the mutilated fish, having previously satisfied himself that they had not been devoured, and stating at length his singular discovery. The professor was astonished, and disbelieved the possibility of the fish being viviparous, imagining some error had crept into the statement sent him by Mr. Jackson; but other fish in a similar state were subsequently obtained by Mr. Carey, and forwarded to the learned professor. The fact was then most undeniably established, that this and many other species were strictly viviparous.
I have spoken of this at some length, because it is a curious coincidence that the same fact should have been discovered by two men a long distance apart, about the same date, and by both in the same way,—by sheer accident.
Now we come to a ticklish question: how are the young fish vitalised in the abdomen of the mother? In this case I shall adopt what I conceive to be the most straightforward course, which is candidly to give my own thoughts, and solicit from abler, older, and better physiologists their opinions or theories—for I sincerely think this is a question well worth careful investigation. I believe the ova, after impregnation, at first goes through the same transformations in the ovarium as it would do, supposing it to have been spawned and fecundated in the ordinary spawning-bed, but only up to a certain point; then, I think, the membrane enfolding the ova, that have by this time assumed a fishlike type, takes on the character and functions of a placental membrane, and the young fish are supplied by an umbilical cord, just as in the case of a fœtal mammal. But a third change takes place. There can be no doubt that the young fish I cut out, and that swam away, had breathed before they were freed from the mother; hence I am led to think that, a short time prior to the birth of the young, sea-water has access to this marsupial sac, washes over the infant fish, the gills assume their normal action, and the regular systemic circle is established. Maturity attained, the umbilical attachment snaps, and the little fish, perfect in every detail of its organisation, is launched into the deep, to brave its many perils, and shift for itself. The strong transverse muscles attached to the powerful sphincter (constituting the genital opening acting from the abdominal walls), I imagine, are in some way concerned in admitting the sea-water, and it appears to me a contrivance admirably adapted to effect such a purpose; but how impregnation takes place, I may at once honestly confess—I do not know.