MEMORANDUM FROM JOHAN HJORT. Sc.D., F.R.S., PROFESSOR AT THE UNIVERSITY OF KRISTIANIA, NORWAY,
reTHE UNFAVOURABLE CONDITIONS FOR COD IN THE WATERS OF LAKE MELVILLE.
The documents placed before me, viz The Memorandum from the Dominion of Canadas Commissioner of Fisheries, the Extract from Dr. E. M. Kindle’s Report of the Geography and Geology of the Lake Melville District considered in the light of modern research in Canadian and North European waters seem to me to give satisfactory proof of the statement made by the Commissioner of the Dominion of Canada in the said Memorandum, “ that the conditions existing in Lake Melville are so unfavourable for Cod, that neither their spawning nor their life-development, nor their adult life would be possible in the waters referred to.” In addition to this the material at disposal seems to me to warrant the conclusion, that no immigration of cod from the Labrador waters into Lake Melville may be expected, in any case not to such an extent that it could be considered of importance for practical fishing operations.
I base this statement, which gives my answer to the question laid before me, viz., “ as to the suitability of the waters of Lake Melville for deep sea codfish ” on the following facts and considerations.
The Norwegian coast and coast-waters resemble in many respects the Labrador coast, and the great cod-fisheries of Norway also bear a close resemblance to the cod-fisheries of the Labrador coast.
We find on both sides of the Atlantic a coast-line hundreds of miles long with large inlets or, as they are called in Norway “ fjords.” In the hydro-graphical character of these fjords there is a great variety. In some of them the depths of coast bank continue like deep-sea-channels into the fjords, such channels having in Norway a depth of several hundred fathoms like the great Laurentian channel of the Gulf of St. Lawrence (See Figure 1). The Canadian Fisheries Expedition 1915. Ottawa 1919, page 22, Fig. 14 which illustrates the field of my investigations in the Gulf of St. Lawrence and which especially gives the depth curves for 200 and for 300 fathoms, as well as the places where floating newly-spawned Cod-eggs were found.
In Norway a distinction is made between two types, sometimes thought to represent different races of Cod. The one belonging to the open waters outside the coast, characterised by its large size, the mature spawning fish
all over 70 or 80 centimeters (i.e., some 30 inches) long. In the long fjords and especially in the southern part of the Norwegian waters, the Skagerrack, there is another type, reaching maturity in some cases at a size of 10 or 11 inches. These types are not everywhere so marked as this, on the contrary there seems to be a great variation in their development according to the natural conditions of the surroundings.
The coast type makes enormous migrations of perhaps thousands of miles during a year, a fact which has been established by accurate marking experiments. (Johan Hjort Fluctuations in the great Fisheries of Northern Europe. Rapports et Procès—verbeaux, Vol. X. Copenhagen 1914). Cod marked in Northern Norway have been found as far south as in the neighbourhood of the town Bergen, but all such migrations take place along and outside the coast, only a small part of the migrating shoals being found at the mouth or a few miles inside the deep fjords, where they may be caught mostly at depths of 50 to 100 fathoms. Among some 5,000 marked cod a
number of some 500 were recaptured none of which were found further in than the mouth of a fjord.
As a proof of this statement, it may be mentioned that in the
year 1919 the catch of large codfish off the coast in the greatest fishing district of Norway, the province Nordland, amounted to some 22,500 tons, while the “ fjordfish ” comprising both immigrating coast fish and the local fjord type amounted to some 890 tons in spite of this district being conspicuous for its large open and deep fjords.
The chart, Figure 2, may serve as an example of the variety of the Norwegian fjords with regard to geographical topography, and it is an experience of a hundreds of years, that no immigration of Cod takes place into fjords, where barriers exist and shallow entrances lead into deeper and wider basins farther inland. The water on such barriers may have all depths from say 50 fathoms up to one or two fathoms and the deep basin behind the entrance may be several hundred fathoms deep.
The natural conditions of this special class of fjords have long been an interesting subject for study. In the year 1897 I discovered—(Report on Norwegian Fishery and Marine Investigations, Vol. 1. 1900)—that in the so called “ Drammensfjord ” a branch of the Christiania fjord, the water was deficient in Oxygen and poisoned by hydrogen sulphide (H2S) which of all living organisms only permits some special kind of bacteria to live in the water. Similar conditions were previously found in the Black Sea. Since then extensive and very valuable investigations have been made by Dr. T. Gaarder (Torbjørn Gaarder. Surstoffet i fjordene. Bergens Museums Aarbok 1915–1916)—who determined the oxygen present in the seawater at different depths of a long series of different fjords at different months of the year.
In the following figures (3–5) some examples of his work are given. In these figures the amount of oxygen is expressed in percentages of normal saturation of seawater under the temperatures present. Figure 3 gives an example from the station marked 11 (on the chart, fig. 2) which is situated fairly near the coast in a fjord having a deep channel from the outside waters, and it will be seen that the percentage of oxygen in the seawater here is fairly high (over 90%) all through the year even in depths down to 600 meters (over 300 fathoms). In the other figure (4 and 5) examples are given from fjords having shallow entrances (about 3 meters) and deep basins behind. Here the percentage of oxygen approaches zero in the deep water in any case in some parts of the year. Other examples contained in the paper show intermediate conditions and the whole work furnishes valuable material in explanation of the important fact that these fjords are so poor in organic life and that the great fish-shoals of the outside waters never migrate into these stagnant basins.
From the admiralty chart (No. 375, Sandwich Bay to Nain) it is evident that the depths at the entrance to Lake Melville through the Narrows off Rigoulette may not exceed some ten, or at the most twelve fathoms. The depths of the lake itself are much greater, at least 100 fathoms. From the surrounding land large rivers pour enormous quantities of fresh water into the lake. From this there must result a strong outgoing current carrying very fresh water, which is borne out by the low specific gravity on the surface and at the bottom off Rigoulette observed by Dr. Kindle on the 20th July and by the many observations of low salinity in the surface waters of the lake.
On the other hand there may be a possibility of an accidental and very rare inflow of water from outside at such periods of the year when the outflow of fresh water stops, but the lack of importance of this inflow is evident from