74 



NA TURE 



\Nov. 28, 1889 



phical labours as his are unsurpassed in hardship, and 

 the results obtained make his work one of the most im- 

 portant and fruitful researches of the time. 



THE HABITS OF THE SALMON. 



The Habits of the Salmon. By John P. Traherne. 

 (London : Chapman and Hall, 1889.) 



THE Stormontfield breeding- ponds have taught us 

 much of the history of the salmon from the eggs to 

 the smolt stage. After that he passes to the sea, beyond 

 the reach of observation, and, with the exception of what 

 we have learned from the return to the rivers of fish that 

 have been marked before their passage to the sea, all that 

 purports to be knowledge of the habits of the fish is really 

 only guesses at truth. 



Theories by a practical salmon-fisher, of wide experi- 

 ence, are entitled to respectful examination. This Major 

 Traherne can claim ; more than that he does not claim. 

 The arrangement of the chapters in the book is objec- 

 tionable as tending to confusion. It would be preferable 

 to take first the chapter on smolts, and then to follow 

 the life of the fish through its grilse, salmon, and kelt 

 stages. 



Notwithstanding that "smolts bred in the Stormont- 

 field, Howietown, and other fish ponds have never as 

 yet been known to evince the least desire to go to sea 

 before the spring months," yet Major Traherne is of 

 opinion, and supports his opinion with good evidence, 

 that there is a double emigration of smolts — autumn 

 as well as spring. Smolts that are bred artificially are 

 always the produce of ova spawned in November, and 

 these form the spring migration. It is assumed that 

 the later spawned ova form the autumn migration. If 

 this be so, it may explain the mystery of the spring and 

 summer run of fish. It is proved that smolts leaving 

 Stormontfield ponds in the spring have returned to the 

 river as grilses in July of the same year, having increased 

 in weight from 3 to 9 pounds each, the grilse caught on 

 July I weighing 3 pounds, and that caught on July 31 

 weighing 9^ pounds. The smolt would probably weigh 

 about 2 ounces, and the rapidity of growth, without any 

 expense for feeding, should make those who have charge 

 of salmon legislation ponder over the problem of close 

 time. 



What, then, becomes of the autumn emigration of 

 smolts ? Do they come back as spring salmon 1 The first 

 run of spring salmon, like the first run of grilse, is small in 

 size. From 8 to 10 pounds would be the average weight of 

 the first run of spring fish. The spring smolt takes three 

 months to return a grilse ; the autumn smolt would have 

 five months to return a spring salmon. 



We quite agree with Major Traherne that spring fish 

 stay in the rivers to spawn. We also think, from the 

 appearance of the fish, that the early, small spring fish are 

 maiden fish that have never spawned. Are they not the 

 autumn smolts ? 



But all rivers do not have a run of spring fish. Major 

 Traherne says : " I notice that early ascending salmon are 

 far more numerous in rivers that have an annual close 



time commencing on or before September i, than in 

 rivers where the close time commences after that date." 

 This is simply a confusion of cause and effect. It is the 

 early river that causes the early close time, not the early 

 close time that causes the early river. What causes a river 

 to be early ? or, in other words, what causes spring fish to 

 run up one river, and not to run up another 1 Major 

 Traherne replies, the temperature of the river. He con- 

 trasts the early arrival of salmon in Loch Naver with their 

 late arr'val, by way of the Thurso, in Loch More, and he 

 says that the River Naver, being fed by a large, deep loch, 

 is warmer than the Thurso, which runs from a small 

 shallow loch ; therefore the earlier run of fish into Loch 

 Naver ! But the fish run as early up the Thurso River as 

 they do up the Naver River ; so this illustration fails. He 

 afterwards refers to the Shin, the Cassley, and the Oykel, 

 all of which rivers empty themselves into the Kyle of 

 Sutherland. He says that the temperature of the water 

 in the Shin — a river flowing from a very large lake — is 

 higher than the temperature of the Cassley, or the Oykel, 

 which are not fed by big lakes ; and that this is the reason 

 why the Shin is the only river, running into the Kyle of 

 Sutherland, which produces early salmon. We reply by 

 denying the premise. The Shin may be a rather better 

 early salmon river than the Oykel, but it is not an earlier 

 river. The opening day always finds clean fish in the 

 Oykel, and, this year, from one bank, the Oykel yielded 

 thirteen fish in March. Last year the yield of one bank 

 of the Oykel in April was twenty-three fish ; both banks 

 of the Shin yielding thirty fish. Twenty fish in March 

 would be a good yield for the Shin. 



But to come back to the question, What causes a river 

 to be early .^ Certainly it is not the absolute temperature 

 of the river. On the north and east of Scotland the 

 rivers are early, on the west coast they are late. The 

 temperature of the rivers on the west is higher than that 

 of the rivers on the north and east. Contrast the rivers 

 Oykel and Inver. The former rises in the eastern slopes 

 of Ben More in Assynt, and is fed in March and April by 

 the melted snows. It has not any big lock as a reservoir, 

 and in March is often frozen over. The Inver runs out 

 of Loch Assynt at the western foot of Ben More. Little 

 snow lies on the western side of the hill, and Loch Assynt 

 is large and deep. The water of the I nver is higher in 

 temperature than the water of the Oykel. The rivers lie 

 opposite to one another in Sutherlandshire ; the Oykel, 

 icy cold in the spring, running east ; the Inver, much 

 warmer, running west. The cold river is an early river ;. 

 the warm river is late. Major Traherne is therefore wrong 

 when he says that the high temperature of a river makes 

 it early. We say that the relative temperature of the 

 river to the sea into which it empties itself determines 

 the run of the salmon. If the temperature of the river 

 closely approximates to the temperature of the sea the 

 fish will run, no matter how cold both river and sea may 

 be. On the west coast the sea is so warmed by the Gulf 

 Stream that the rivers on that coast, although positively 

 warmer than on the east coast, are, relatively to the sea, 

 colder, and they are accordingly late rivers. 



The relative temperature of the air and the water has 

 a great effect, too, upon the feeding of the salmon. 

 Major Traherne says : " I never expect to meet with a 



