Art. XXV.—Notes on Salmonidæ and their New Home in the South Pacific.
[Contributed to the Wellington Philosophical Society, 15th January, 1901.]
The following notes were read by Mr. A. J. Rutherfurd, Chairman of the Wellington Acclimatisation Society, at the quarterly meeting of that body on the 3rd December. The subjects dealt with are chiefly a description of the waters into which salmon and trout have been introduced in New Zealand, and the results likely to be obtained owing to the change in their surroundings:—
Situated between latitudes 34° and 47° S., in the Pacific Ocean, about a thousand miles from the main Australian Continent, the islands of New Zealand form an exceedingly interesting group, with their unique flora and fauna. They
lie on the upper edge of the “Roaring Forties,” along which the westerly gales (forming the northern parts of circular storms that extend into the Tasman Sea) prevail, so useful to eastward-bound vessels. Generally the ocean shelves off into deep water close to the coast, so that the conditions are widely different from those in the comparatively shallow North Sea, and approach more nearly to those of the Pacific Coasts of South America.
The fish frequenting the coasts of New Zealand correspond somewhat with those found in similar latitudes in the Northern Hemisphere—say, between Portugal and Madeira; and, roughly dividing the ocean belts into tropical, subtropical, temperate, and frigid zones, I think that the ocean surrounding New Zealand may be classed as intermediate between subtropical and temperate.
The great ocean-currents surrounding these Islands have a distinct bearing on the question under discussion, and I give my theories for what they are worth. In the ever-restless Pacific there is always a creep north of the waters cooled by the melting ice of the antarctic circle, which, sinking down, trend north in the deeper ocean. Conversely, there is always a set south of the warm water from the tropics, moving slowly along nearer the surface. Together with these two forces, there is a great easterly current influenced by the prevailing westerly gales, which, owing to the contour of New Zealand, is deflected towards the Chatham Islands.
In support of this theory I may mention the following interesting facts, supplied to me by Mr. Frederick Chapman, of Dunedin: (1.) Telegraph-poles washed overboard from the s.s. “Hinemoa,” in Foveaux Strait, were some five weeks afterwards found at the Chatham Islands.—(Captain Fairchild.) (2.) A bucket washed overboard from the ship “New York,” between the Snares and Auckland Islands, landed at the Chathams before the ship reached England. (3.) Wreckage from the Snares (ship “Assaye”) landed on the Chathams, and supplied the inhabitants with candles. (4.) A supply of candles was washed ashore at the Chathams from the wreckage of the ship “Lastingham,” wrecked in Cook Strait. (5.) Ice seen at the Chathams a few years ago was previously unknown to the Maoris, who have probably only been living on the islands sixty or seventy years. It is, however, reported that many years ago icebergs were stranded on Mahia Peninsula, north of Napier, and affected the climate there for three successive seasons.
Ice is seldom found so far north as the Auckland Islands, but it reaches into the Australian Bight, and very rarely up towards the Chathams. In other words, the ice-line sweeps south to clear New Zealand.
The cold antarctic flow probably rises as it strikes the shallow water on the south-east of New Zealand, and, working up the coast, seems to baffle between Otago Heads and Cook Strait with the warm tropical current which washes the northern end of New Zealand, works south into Cook Strait, and down the west coast of the South Island.
The usual meeting-place is probably somewhere about Banks Peninsula, but after a prevalence of southerly weather fish frequenting the colder waters are found as far north as Cook Strait. It may be that the meeting-place of these ocean-currents is one of the principal causes of the fogs so prevalent about Banks Peninsula, and, after southerly weather, in Cook Strait.
The migrations of the kanae, or grey mullet, seem to me to indicate the extreme limit of the warmer current, whilst the flying-fish, common enough in the Hauraki Gulf and Bay of Plenty, follows the flow of warmer water. The prevalence of mangrove vegetation in the estuaries in the northern parts of the Auckland Provincial District shows that the seaboard is directly influenced by the warm currents, which no doubt carried the floating seeds of this plant to the coast of New Zealand.
The kanae do not seem to work further down the coast than the estuaries running into Cook Strait, and I am not aware of their being caught south of Wellington Harbour. I believe they migrate with the seasons between the north of New Zealand and the extreme edge of the warmer current, in the same way that their representatives in the Mediterranean Sea migrate in similar latitudes on the Italian coast.
II. Rivers, Lakes, and Streams.
The beautiful system of rivers and lakes in New Zealand were recognised by the early settlers as admirably adapted for the well-being of Salmonidæ. In the South Island the rivers for the most part originate among snow-clad mountains of hard rock formations, flowing down through the low country, with shingle bottoms, which form excellent spawning-beds for trout. In parts of the North Island the same formations prevail to a large extent, but many of the rivers, such as the Manawatu, Ruamahanga, and Hawke's Bay Rivers, run for the greater length of their course through low country, and are not essentially snow-fed, though some of their tributaries are. The question of the chemical constitution of the water has never been carefully gone into, but I am inclined to think that in many of our mountain torrents and inland lakes there is a deficiency of salt; this, however, could only be determined by a careful experimental analysis.
As the geological formation is the basis of the banks and
river-bed, so the fertility of the soil through which a river flows (altitude, climate, exposure, and the temperature of the water being also taken into consideration) determines the abundance and quality of the vegetation on land and under the water, and the supply of insect life, Crustaceans, &c., which form the staple food of the trout. As a rule cold snow-fed rivers contain much less food than those draining warmer lower levels, and the fish in them are later in getting into condition.
It must be borne in mind that each river has a limited permanent carrying-capacity, and will only do justice to a certain stock of fish. If overstocked the result must inevitably be deterioration; hence it may be expected that in time our non-migratory Salmonidæ will deteriorate in size, and that we must look to annual visitors from the ocean (which, owing to the configuration of these Islands, is never far away) to keep up the record this colony holds for growing big trout, largely established at first by the fact that the virgin waters in which they were liberated contained abnormal quantities of food.
III. Indigenous Fish.
Before proceeding to discuss subjects surrounding the introduction of Salmonidæ into New Zealand, it may be interesting to take a cursory glance at some of the indigenous fish inhabiting our rivers. The only true representative of the Salmonidæ is the beautiful little Retropinna, or smelt, two varieties of which at least are found in our rivers and lakes. Somewhat allied to this fish, the graceful upokororo (Prototroctes oxyrhynchus), or native grayling, about whose life-history and habits so little is known, is found in many of our streams. The upokororo used to be plentiful in our rivers, but of late years have been thinned out by the formidable trout we have introduced, by mining operations, and, no doubt, by clearing the bank vegetation for farming purposes. It is said to be an almost unique variety, very like the Haplochiton, which inhabits the cold, fresh waters of Tierra del Fuego, and is allied to a fish found in Australia, the Yarra herring. Though said to differ from a true Salmonoid in certain structures, it is, I believe, a representative of the family in this hemisphere. I have never heard of their being taken in salt water, but they certainly have a habit of disappearing and reappearing again in a ghostly fashion, which makes one wish for a further acquaintance with their migrations and spawning habits. I would suggest that the Westland Acclimatisation Society, who have their hatchery in a suitable place, be asked to keep some in their ponds for the purpose of studying their life-history.
The strictly fresh-water varieties of fish (such as carp) are intolerant of salt water, and on examination of the indigenous fresh-water varieties in this colony it will, I think, be found that they are all more or less tolerant of salt water, and probably, almost without exception, descended from marine ancestry at no very remote period in the world's history. Many of them, such as the smelt, eels, and inanga, at times frequent salt and brackish water; while some of our marine fishes, such as the flounder, grey mullet, and kahawai, run up into fresh water, the two former living and thriving in some waters in the North Island where they cannot obtain constant and permanent access to the sea.
IV. Salmonidæ in General.
In his opening chapter on Salmonidæ, Dr. Günther remarks that there is no other group of fishes which offers so many difficulties with regard to the distinction of the species, as well as certain points in their life-history, as this family. Their almost infinite variety is dependent on age, sexual development, food, the ever-varying properties of water, and the tendency to interbreed exhibited by many of the so-called varieties. Colouration seldom assists us in distinguishing the species, varying as it does with the haunts of the fish and the seasons of the year. It is imitative, the colour of the fish, rapidly adapting itself to its surroundings. A living trout of dark colour placed in a white basin full of water becomes pale in half an hour, and in some days almost white. Conversely, a trout of light colour placed in a black vessel rapidly assumes the colour of the bottom. Hence, in almost every river the varieties of trout have local peculiarities of colour, which are favourable as a protection to the fish against its natural enemies. As a rule, clear rapid rivers produce trout with intense ocellated spots. In large lakes with pebbly bottoms the same fish are bright and silvery, with x-shaped black spots. In pools and parts of lakes with a muddy or peaty bottom they are of a darker colour generally, smudged and blotchy in their marking; and, when enclosed in caves and dark holes with but little light, often jet-black or nearly so. The action of brackish or salt water soon gives them a bright or silvery coat, as a rule sparsely spotted, none of the spots being ocellated.
Size depends chiefly on the amount of suitable food available, and the colour of the flesh on the particular nature of the food, the pink or red colour being probably produced by the red pigment of many salt and fresh-water Crustaceans on which they greedily feed.
This group of fish may be divided into many varieties, including the Salmones proper, such as the species of salmon
found in the Atlantic and Pacific Oceans, the many varieties and hybrids of the subgenera called trout—the Salvelini, or char; the Coregoni, such as the whitefish of America; the Thymallus, or grayling, &c.
Without going into the larger and more scientific question affecting the groups of this fish, which would require much study and elaboration, I wish in this short paper to discuss a few of the interesting questions involved in the introduction into the waters of the southern Pacific Ocean and rivers of the Islands of New Zealand of several forms of Salmonoids.
V. Salmonidæ Proper.
By these fish I mean the larger species, which live in the sea from the time they have reached the smolt stage, and only run into fresh water for the purpose of reproducing their species, or at times, perhaps, to rid themselves of sea parasites. From the time these fish enter the river they begin to deteriorate in condition, and when imprisoned in fresh water gradually lose many of their finest characteristics. The necessity for seeking their sustenance in the sea will be quite apparent if we reflect on the enormous quantity of food which would be required to feed the millions of large fish which annually run up the salmon rivers in the North to spawn.
Hitherto three species of the true Salmones have been introduced into the colony: (1.) The Salmo salar, or Atlantic species, the ova of which has been imported in large quantities, and a considerable number have been reproduced in captivity. This is the finest sporting species known, but its migrations in the Northern Hemisphere are chiefly confined to the temperate and sub-arctic zones, and hitherto its introduction has not been, as far as we know, permanently successful. This is much to be regretted from every point of view, and it would be of the utmost value to the colony if this fish could be successfully acclimatised. (2.) The Oncorhynchus tschawytscha, king, chinook, or quinnat salmon, a species growing to a large size. (3.) The Oncorhynchus nerka, sock-eye or blue-backed salmon, a smaller thick-set variety much used for canning in the Columbia River, some of the ova of which were introduced in one of the shipments to New Zealand. These—(2) and (3)—are species found in the North Pacific, and have a much wider geographical range than the Atlantic species, some of them being found from the far north down to Monterey Bay, in southern California, as well as in Japan and in northern Asia. Some of the ova of the quinnat and blue-back varieties have been introduced and the fry liberated. Fish caught in the Waitaki River have been sent to London and have, I am informed, been identified as belonging to the species found in the Pacific.
On the whole, I am inclined to think that, owing to our geographical position and ocean surroundings, we are more likely to be successful in introducing the forms of salmon found in the northern Pacific than our old friend Salmo salar of the Atlantic, which is a more delicate fish, and would probably find difficulties in ocean surroundings so widely different from those in its northern home.
It has been urged that it is a pity to introduce fish which do not, as a rule, give good sport in our rivers, though they are excellent sporting fish in the sea and estuaries. I do not think we need fear this at all. In introducing these fish we are stocking the ocean with very valuable fish from a commercial point of view; and I can see no reason why several varieties of salmon should not flourish on our coasts, and run up the rivers at different times of the year, as they do in the western rivers in Canada and the United States, in countless thousands. I believe, myself, that, owing to the warmer ocean-currents striking the coasts of the North Island, the best salmon rivers will be in the South, and consider that it will be good policy to endeavour to introduce the best species of salmon found on the coasts of British Columbia, Oregon, and California; and in doing so I think we shall succeed in permanently establishing one or more of these species, which will form a very valuable addition to the fishes of New Zealand, as well as probably of Tasmania, and any small islands to the south where there may be suitable streams for spawning.
VI. Salmo trutta, or Trout.
A number of varieties of trout have from time to time been introduced into New Zealand, such as Salmo fario, or brown trout; Salmo levenensis, or Loch Leven trout; Salmo samardii, variety, Scotch burn trout; Salmo trutta, sewen, sea trout, or white trout. Probably some of the ova originally brought out was crossed more or less with a strain of the Salmo eriox, or bull trout.
All these fish are gradually accommodating themselves to their new environment, and becoming very like the varieties found in corresponding northern latitudes—say, in Switzerland and northern Italy. Our Lake Wakatipu trout are almost identical with the trout I saw taken in the northern Italian lakes in nearly similar latitudes, and very much alike in their habits.
I believe, myself, that the varieties and hybrids of Salmonidæ called “trout” are merely one species, subject to animmense amount of variation, many of the larger forms of which seek their food, whenever conveniently situated, in the ocean, and run up the rivers like salmon to perpetuate their
species; but it is probable that they do not make such lengthened journeys at sea as the salmon proper are supposed to do, but frequent the shallower water on the coast.
Even within the limits of a single species (so-called) no two are found to be exactly similar, but there is a tendency to diverge from the original type in such direction as to preserve and increase useful varieties—a law of variability by adaptation, which is destined to modify every organism so as to fit it for new conditions of existence. A notable instance of this occurs in the gillaroo trout of Ireland, which have developed quasi-gizzards to enable them to crush and digest the small fresh-water snails and shells found in certain lakes. It will be interesting to watch whether similar developments are found in any of the varieties in our lakes at the antipodes.
In short, my theory is that, whatever variety we liberate of the ordinary species of trout, it will develope into a Salmo novæ-zealandiæ, suited to the water in which it is liberated, and corresponding with trout in similar latitudes in the Northern Hemisphere more closely than with the varieties found in the more northern latitudes of our Mother-country. I do not think that these fish will retain the characteristics of the variety found in the environment from which they were taken, and consider that the results already obtained in New Zealand have proved this.
VII. Salmo Irideus.
Turning to a more subtle family, the Salmo irideus, or rainbow trout, which we have successfully introduced into several of our rivers in the colony, there is considerable controversy as to what this variety really is. The progeny of ova taken from the Salmo gardneri, or steel-head, of British Columbia, are apparently identical with the progeny of the rainbow trout, and it is commonly believed by some of the experts that they are the same fish, and that the rainbow trout when it takes to sea-going habits developes into the steel-head. It will be very interesting to see whether this proves to be the case in New Zealand.
Personally, I am inclined to think that this species, in common with the rest of the trout on the Pacific Slope, is more allied to the char family than the trout. Its spawning habits are not like those of the trout, and in its play when hooked it is like a salmon. It lacks many of the shy habits of the trout, and is certainly the best sporting fish we have yet introduced. I do not think there is any probability of this variety crossing with the brown trout in our rivers, and I doubt their thriving well together.
There seems to be a marked divergence in species between
the forms of salmon and trout indigenous to the Atlantic and Pacific Oceans.
VIII. Salmo salvelini.
The Char family proper are a beautiful, but more delicate, variety of Salmonoid, shorter lived, and most of their forms requiring deeper and colder water than the trout. We have introduced the American brook char (Salvelinus fontinalis), but have not been very successful with these fish. The only stream I know which is well stocked is the Tahuna-atara Stream, between Rotorua and Taupo, which is full of them, and contains no brown trout. They are evidently very difficult to establish, and attempts to do so have proved a failure in most places, both in England and on the Continent, though in enclosed private waters they have been successfully propagated and are easily handled. My experience with them in the Tahuna-atara was that they were fairly easily caught with a small spinning bait, like a “halcyon spinner,” but that they did not rise well at the fly. When caught they made a few strong rushes, and then gave in without a long fight. For the table they are extremely rich and well flavoured, running, in that stream, up to about 6 Ib. in weight, and averaging about 2 lb.
I consider that it would be worth while trying to import the saibling (Salmo salvelinus) from Europe, and introduce it into our lakes. It is a lively and delicate fish, and it is probable that the S. alpinus and S.umbla are varieties of the same fish, and that we may develope a beautiful variety of our own in some of the clear, deep lakes of New Zealand.
A few eggs of the S.alpinus arrived and were hatched out at Masterton some years ago, but the young fish died, and for the present we have lost the breed.
IX. Salmo carpio (Trutta Lacustris Carpioni).
Some years ago we imported and reared to maturity some of a very fine variety of deep-lake trout, the Salmo carpio, or carp trout, of Lago di Garda, in northern Italy, a kind much valued as a table fish by the Italians. This fish has proved very difficult to introduce into any waters where it has been tried, and, unfortunately, owing to a want of knowledge of its habits, we have lost the breed.
The Salmo carpio live at a great depth, and the best chance would have been to have liberated the young fish in one of the deep lakes in the South Island and let them take their chance. The shallow ponds of our hatcheries were unsuitable to them. Dr. Bettoni, of Brescia, promised to supply us with a further consignment from the Italian Government hatchery at Peschiera if we required them, and, if
possible, another attempt should be made to introduce this fine fish. It is not a sporting fish, being caught trolling at a great depth, but is a very valuable fish, to net for market, and one of the most interesting of the varieties of the varieties of Salmonidæ found in deep lakes.
The Coregonus albus, or whitefish, of America is a most valuable fish from a table and food-supply point of view, and, though no good for sport, should suit our lakes well. Several successful importations of ova have been made, and it is more than probable that these fish are now in Lake Rotoiti, in the Nelson Provincial District. The whitefish fisheries in America are large and of great value, and I think we should persevere in attempts to introduce the Coregoni until a planked whitefish becomes a recognised delicacy in the hostelries adjoining our magnificent lakes. Once established in any lake, we could easily transport them to the other lakes of the colony.
The subjects on which I have ventured briefly to touch in the short space of time at my disposal are, I think, interesting ones, which might with advantage be enlarged upon ad infinitum.
I wish you to picture to yourselves the position of these Islands, far out in the southern Pacific, with ocean surroundings differing widely from those on the British coast. Then study, analyse, and make notes on the results already obtained from the introduction of various forms of Salmonidæ into entirely new environments—results which closely resemble those obtained in our sister-colony, Tasmania, and are of great interest in helping to solve problems in the scientific world. They seem to me to prove the truth of the theories I have advanced, many of which are practically those held by Dr. Francis Day, to whose works I am much indebted in writing this paper. This will, I think, give us a clearer conception of the scope of one branch of the work of acclimatisation and the far-reaching benefits we may hope to obtain if we strive conscientiously to people our waters with new forms of life, valuable not only from a sporting point of view and as an attraction to tourists, but best suited to the wants of the inhabitants of this fair land of our adoption.