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2. Additional Observations on the Fungus Disease affecting Salmon and other Fish

Published online by Cambridge University Press:  15 September 2014

A. B. Stirling
Affiliation:
Assistant Curator of the Anatomical Museum of theUniversity of Edinburgh.
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Extract

In my former paper, read before the Society in June 1878, I gave an account of observations which I had made on the fungus disease affecting salmon, and described the character of the fungus, which I referred to Saprolegnia ferax.

In the present communication I propose to relate additional observations, and to discuss the theories which have been advanced by different writers in explanation of the cause of the disease. Four theories have been advocated, namely—pollution of rivers, overcrowding, absence of frost, diseased kelts and addled ova.

Type
Proceedings 1878–79
Copyright
Copyright © Royal Society of Edinburgh 1880

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References

page 232 note * See Proceedings of that date.

page 234 note * Since this reference to the Carham pond fish was read to the Society, it has been stated by Inspector Johnston of the Berwickshire Police that several fish had been found dead in the pond, which, in his opinion, had died of fungus disease. Those deaths, of which there can be no doubt, took place between 11th February and 3d May 1879, embracing a period of eighty-two days, during which five fish had been found dead in the pond by Mrs Robson, the gamekeeper's wife, who fed them. These fish were shown to Inspector Johnston, who apparently paid official visits to the pond, and from the appearance of the fish he concluded they had died of fungus disease. I do not accept Mr Johnston's opinion on this point. He was well aware that I was engaged in a scientific investigation of the disease; indeed he had, by order of Mr List, chief-constable, caught in the Tweed and forwarded to me several salmon to aid me in my research. It is singular then, that, knowing the interest I took in the pond fish, he was silent, and did not at the time report upon the disease, which, according to his version, had existed in the pond for eighty-two days, a period of sufficient length for the fungus to have destroyed the fish, both root and branch; also, according to his own statement, no one saw the dead fish, with the exception of himself and Mrs Robson, and probably Mr Robson, the gamekeeper; and, consequently, there is no scientific evidence that the cause of death was Saprolegnia ferax; and, to quote the words used by Mr List in a letter to me of 21st June, “if Saprolegnia ferax had been in the pond, it must have been seen on the fish on the 22d May, when we saw every one of them.” Taking those facts into consideration, I adhere to my statement thatthe case of the Carham pond fish fully proves that overcrowding is not the cause of fungus disease.

On the other side of the question—The pond-fish had been at least ten times specially examined during the five years they had been detained in it. By invitation of the chairman, I was present on two of those occasions, along with members of the experimental committee, Mr List the conductor of the experiment, a number of other gentlemen and practical fishermen, and it was a matter of surprise to all present that the fish were found in such fine condition. At the final examination, which took place on 22d May 1879, I was prevented from being present, but arrangements were made that if any fish were found bearing marks of the disease they were to be transmitted to me. On the following day Mr List wrote to me that the “fish were in splendid condition for kelts, not the slightest sign of disease on any one of them.”

It is well known among taxmen, practical fishermen, bailiffs, and anglers, that it is usual to find dead and dying salmon and sea-trout in rivers every season after they have spawned. This kind of mortality has been observed and written about for upwards of two hundred years. Isaac Walton mentions this as well known in his time, and there is no reason why the Carham détenus should be an exception to this rule, seeing they had spawned twice or thrice during their detention.

page 246 note * Cited by Dr Burdon Sanderson in his paper on the “Vegetable Ovum,” Cyclopœdia of Anatomy and Physiology, edited by Dr Todd.