NEW ZEALAND FISHERISES. AND THE DESIRABILITY OF INTRODUCING NEW SPECIES OF SEA FISH.

Otago Witness, Issue 2179, 28 November 1895, Page 49

NEW ZEALAND FISHERISES. AND THE DESIRABILITY OF INTRODUCING NEW SPECIES OF SEA FISH.

By Geo. M. Thomson, F.L.S. (Read before tbe OtaAo Institute on October 8.) 11. When one considers the enormous number of ova produced by most species of fisb, it is difficult to believe that any amount of fishing oan make the slightest appreciable difference in the available supply. We have absolutely no data regarding the number of ova produced by our New Zealand fishes, but trustworthy and accurate information has been collected regarding many of the European species. The following figures are taken from the ninth Annual Report of the Fishery Board for Scotland, 1890 (p. 254, &c). The number of ova taken from a single individual of the following species was :— 1. Herring, 22,000 to 47.000. 2. Whitirg, 109,000 to 131,000. 3. Haddock. 156 009 to 806 000. 4. Brill, 825,000. 5. Halibut. 1.490.0C0 to 4,451 000. 0 6. Cod, 2,063,000 to 6,652,000. - 7. Turbot. 5.612 000 to 10,1 14. 000. 8. Ling, 12,300,100 to 23.360,00)). One large Ssh of the last-named species, 9G : .n long, weighing 86lb, had a roe weighing 141b, and estimated to contain 60,000,000 ova. Dr T. Wemyss Fulton, who is at the head of the scientific department of the Scotch Fisher; Board, points out in the report jaist quoted that the Royal Commission of 1854 recommended that no restrictions whatever should be mad* in regard to the sea fisheries, and, as the late Professor Huxley put it, everyone should be" free to fish " where you like, when you like, and as you like." The Royal Commission appointed in Belgium in 1865 made tbe same recommendations. The Scotch Commissioners of 18G3 66 " want very exhaustively into tbe subject, and apparently found no trustwoithy evidence of over-fishing ; and they recommended * that all acts of Parliament which profess to regulate or restrict the mode of fishing pursued in the open sea be repealed, and that unrestricted freedom of fishing be permitted hereafter,' " and this was done by tbe act of 1868. Tne Commission of 1878 stated " that there was no evidence that the 6upply of fish generally on tbe coasts of Er gland and Wales is decreasing " ; while the last great Cjmmusion stated that as regards offshore waters " no decrease, except in the case of soles, has been proved in the total takes of ' the North Sea." Since the publication of the report of this Commission several biologicfl stations have entered on the investigation of the question, and Dr Fulton points out (chap. ' I, p. 274) that " within tbe last few years a certain amonnt of definite knowledge b&i come to the surface, paiticularly in relation to the North Sea fisheries, which leave no room for doubt that over fishing has cccurred, atd is going on to a sarious extent." This over-fishing he attributes to tbe rapidly augmenting populations around the North Sea, and the vast increase in tbe extent and efficiency of the machinery of fuhiog. It is difficult to give any thing like acorrect estimate of the great number of boats and men engaged in the fisheries of the North Sea and its ntigliboui hood. To take Scotland alone:— ln 1889 over 49,000 men and boys were employed in tbe boats, beeideß 50,000 who- fcusd cccupation on th^re ; 15,000 boats of a total tonnpge of 125 000 tons, valued at. £777,000, together with nets valued at £713,000 and lines at. £125,000, were in use. In tbe same year 38 steam trawlers of 43G9 tons burdop, valued at £110,000, were emplojed; but in 1891, two years later, tbe number of steamers had increased to Gl, of 5929 tonp, and valued at £208,000. The majority of these boats were employed in the North Sea. When we remember that in addition an immense number of boats are employed by England, France, Belgium, Holland, Germany, Denmark, Norway, and Sweden, fiihirig in tbe same limited area, we need not be surprised that the total available number of certain kinds of fish in the North Sea has of late shown signs of cUminishiDg. But no such possibilities occur in this colony. It is turrounded on all sides by an ocean of vast extent. The population of the coast lines of the habitable lands in these southern seas is extremely sparse, and is not likely to become very dense for a coneiderabla length of time, so that there is no possibility of even perceptibly diminishing the fish supply, as far as all offshore fisb are concerned. This being so, it seems to me that while clause 12 of the act of 1894 giving the Governor power to declare any special fish proteotod should stand, the Oider-in- Council of 2 -id May last might, without any harm to the fisheries and with advantage to fishermen, be rescinded, and that a new order Bhould be issued protecting only all flatfish and grey mullet (Mugil peiusii) up to a certain size. A second obj action against the regulation of 2ad" May, as gazetted, is the want of scientific accuracy in the schedule. The meet of the fish named are well enough known by their popular appellation perhaps to stand, but several are obscure. If the regulation is to remain in force these ought to be more strictly defined. For instance, ' what is mullet ? In Auckland the grey mullet, or karae (Mugil perusii), is meant; in Danedin it is the sea mullet (Agonostoma Jforsteri), a totally different fish. The schedule limits the size of the blue cod td Boz, and of the rock cod to Boz, But these two names apply to one and the same fish (Percis colias), tbe first name being that by which it is known in the southern part of the oolony. Lastly, what is meant by the herring? The so-called Picton herring is „ affirmed by some to be the sea mullet (Agocostoma), while the fish which Is so abundant round the southern and south-eastern coasts of this iiland in the early part of the year is the sardine or pilchard (Olupea sagax). Tho general conclusion I would arrive at Is that there is very little need for fisheries legislation at the present time in this colony, particularly as such legislation is apt merely to harass thofo engaged in a struggling industrj, without vut comD§nj!Rtin« 9,<Xv9,U\

tage to either the oommunlty_atjargo or to the industry itself. "~~~ — 111. I now come to the third portion of my subjeot — viz., the possibility or advisability of INTRODUCING NEW AND DESIRABLE SPECIES OP FISH INTO THE NEW ZEALAND SEAS. And in this connection I would for the present confine my remarks to the following fishes :• Cod, herring, and turbot ; and to one crustacean, the edible crab, or partan, of Britain (Cancer pagurus). I wrote to Dr Fulton last year on this question, and he has favoured me at some length with his views on it. I quote the following extracts from his letter of Bth November, 1894:— "It seems to me that two points should first of all be cleared up before the experiment ia tried— first, the physical and biological condition of ths area where it is proposed to place the fish or their eggs, so far as it may affect the experiment; and, secondly, the means and methods of transport that may be available. The introduction of a new form in this way may be done by means of a considerable number of adults before the spawning time, or by-eggs or fry, but in any case the success of the experiment will depend upDn the survival of the firsi generation to tbe reproductive period in numbers sufficient to carry on the species. The two pointß in regard to the physical conditions wbicb should be investigated are the temperature and the currents, both of which might be simply ascertained, I need say nothing about tbe influence of the temperature, exespt that it has been too much exaggerated ; but from experiments we have now in progress, it appears that the action of the enrrents might have an important bearing upon the case by transporting the pelagic ova or fry a considerable distance from the place where they, or the adults producing them*, were placed in the sea. " In regard to the biological conditions, it would be jmportant to ascartain the spawning time of the native species and when their eggs and laivat are found in greatest abundance in tbe sea ; for it can scarcely be doubted that that would be the preferable time to intrvduce the new forms, as the minute life upon which larval fishes prey is then most abundant", and tbe other conditions most suitable." It would «em at first sight;, from the enormous fecundity especially of tbe cod and turbot, that even if one or two adult fi»h could be introduced into these sea?, and their ova were once liberated and fertilired, the experiment would be bound to succeed. But a remark of Dc Fulton's on this matter if worth quo' ing here. He says : — " A single female turbot may produce in one serson 9,000,000 or 10,000,000, a cod G 000,000 or 7,000,000, a ling 20,000,000 or 30 000.000, a haddock 500,000 to about 1,000,000, and so on. The import of this enormous fecundity has frequently been altogether misunderstood ; arguments have been based upon it to show the inutilily of interference in fisheries. In reality fecundity is a measure of the natural destruction that occurs In the life history of any species, eicce, on tha> reasonable assumption that the total^numbsr cf a species remains faiily constant over a period, it is only necessary that a few individuate of the new generation Bhould, on the average, survive to the reproductive stage in order to keep up tbe relative abundance of that species. Hence the proportion of the eggs produced by sea fishes which give rise to reproduotive individuals is infinitesimal. Of the 10,000,000 produced by the turbot, 9,999,998, or thereabout, take no part in the pioduction of another generation, but are destroyed at one period or another when left to na'ural conditions. So with other species." — Tenth Annual Report-, page 190. The enemies which the young fish would have to encounter here are just as numerous as in their native seas ; so that, unless tbe young fish after escaping from tbe egg were protected for a time, the chances against their survival would be very great. In order to arrive at any sure ground on which to base conclusions, I propose to consider, firs'", what is known about the life history of these fibh bearing on this subject ; and, second, what we require to know about local conditions as affecting tbe possibilities of carrying out any experiment to a successful issue. My facts under the first head are chiefly drawn from the Annual Reports of tbe Scotch Fishery Board, supplemented by papers in tbe Journal of the Maiine Biological Association of Great Britain. The cod (Gad us morrhua) spawns in Scottish waters from about the end of January to the end of May, but chiefly in March. As is the case with the majority of food fishe?, the eggs float at the surface of the water and remain floating up to the time ef hatching. The ova hatch out in about 14 days, when the temperature of the water is G 52deg C. This seems to be about an average temperature for the surface waters of the east of Scotland towards the end of April. With a j lower temperature the process of hatching is retarded. I have no data with regard to the cod, but, taking the figures given in the twelfth annual report for tbe plaice. I find that with a temperature averaging 5 24deg C. the eggs took 21 days to liatch out^while at 886deg C they only took 14 days. By lowering the temperature of the water in the hatching boxes it would then be quite easy to retard the hatching for some weeks. In January, February, and March, when cod begin to spawn, the temperature may range from 3df g to sdeg 0., but it would seem that very few fish hatch out till April, when the temperature begins to rise steadily. It would therefore be a very simple matter to obtain eggs during these months, and transmit them to Njew Zealand by direct steamer in suitable boxes supplied with a steady stream of sea water cooled probably to Odeg 0., as recommended by those competent to do so. Such eggs would arrive in the colony in the month of May, and would have to be dealt with at once. Perhaps adult cod could be brought out in suitable tanks. Dr Fulton, however, seems to think that the carriage of round fish will always be a matter of greater difficulty than that of fiat fish, and there really seems no reason why fertilised ova could not be easily carried and kept during the voyage at such a temperature that their hatching could be retarded for several weeks. The hatching of cod and the protection of the fry for a very brief period is now carried r on on a Y&et ml? jji tfiiuu cflunteifia. jftJwa

it is remembered that the greatest destruction of fish takes place while they are still in the egg, the ova being cast forth by millions into the open sea, and devoured in the great majority of cases before they can hatch, it will bo seen that the protection and hatching of the eggs is the all-important step towards reducing the death rate among them.

In 1892 the Dlldo hatchery in Newfoundland liberated 39,050,000 cod fry ; tbe Wood's Holl station in New England batched out 7,820,000 (in 1891, 36,000,000); while the great F oievig hatchery at Arendal, Norway, hatched and planted 207,000,000. The Dunbar hatchery in Scotland was only opened in 1893, and operations were chiefly confined to the hatching of plaice, of which over 26,000.000 fry were liberated. Of cod, only 500,000 oggs were hatched, but the hatching house is capable of accommodating 80,000.000 ova at one time, and two lots can be dealt with in a season. Of the 500,000 eggs placed in the hatchery, and which were obtained, not from fi*h kept in the breeding ponds, but from specimens caught and stripped at Bea, it is interesting to know that not above 4 per cent. died. It is clear there would be no difficulty whatever in obtaining ova, nor in getting the services of men thoroughly qualified to oarry on the work oE a hatchery.