Fish: In Relation to Their Surroundings (Classic Reprint) - Softcover

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Excerpt from Fish: In Relation to Their Surroundings

The special interest of this case lies In the fact that during that single night this fish was absolutely exterminated, so far, at any rate, as the area alluded to is concerned, for the reports that have been published during succeeding years have shown that the fish has not been since met with in its old habitats. Our American friends naturally thought that this summary extinction was due to volcanic action 5 but if this were so, it is only natural that other fish, known to be living in the same water, should have 'been destroyed. In the absence Of all but here and there a stray carcase of any other fish, they have come to the conclusion that the destruction was due to a change (and most probably a reduction) in the temperature Of the water, brought about mainly by a churning action and by the fact that they had just passed through an excessively hard winter. Which had left a quantity of ice as its legacy. The possibility that this is a sound conclusion is the greater from the study of more familiar facts concerning the common Cod. When captured these fish are frequently placed in wells in the bottom of the boats, which are exposed to the isea beneath, and it has been found that under these circumstances they may become numbed on being brought into contact with cold water. We thus see that a fish may, be so sensitive to immediate change in its environment, that in a single night a species destined to become one of the most important food fishes of the world may be destroyed. An interesting fact bearing on this question is reported from Tasmania. For many years efforts have been made to acclimatize the English Salmonidae to' Tasmanian waters.' With the Trout there has been success; but although some thousands of pounds have been spent in the endeavour to acclimatise the Salmon, it has been found that when the young Salmon have been reared to the migratory stage, they \disappear. The temperature of the sea into which the River Plenty flows, is found to be 10 degrees higher than that around Great Britain 5 hence it is argued that the young Smolt have been.

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