70 PHYSOSTOMI. 



The salmon appears to possess a homeing instinct which induces them to seek to 

 return to the rivers where they were originally bred, but instances are occasionally 

 brought to notice where such could not have been the case. Thus scarcely a year 

 passes but grilse or salmon are captured off the mouth of the Thames, from 

 which all these fish have long since been destroyed, due to the polluted state 

 of its waters. The majority enter rivers prior to the commencement of the 

 breeding season, others, especially grilse, much earlier, or in companies : many 

 appear to return to the ocean before they re-ascend at the time of the regular 

 immigration. A few would seem to pass up and down the river several times 

 during one year.* In the Rhine, Barfurth observed in 1874, that spawners ascend 

 from September to November, while there is likewise a barren winter variety 

 coming sporadically and for a brief season from September until May. 



Buckland tells us how a friend of his who owns a well-known island on the 

 west coast of Scotland, netted a certain pool in his fishery, and out of a number 

 of fish which he caught, he carefully marked some 20 or 30 : he then put these 

 fish on board his yacht, and keeping them alive sailed right round his island, then 

 up a creek to the mouth of the river, and turned them into a lake about half a 

 mile from the source of the stream from which they had been brought, which, 

 though close to it, was in no way connected, rising from a different watershed. 

 It was as though the salmon had been carried from one heel of an enormous 

 horseshoe round to the other heel, and then taken right into the middle of the 

 horseshoe and then let loose. During the same season some of these marked ones 

 were caught in or near their own pool, to do which they must have come back a 

 circuit of at least 40 miles, and passed by six or seven tributaries. 



When descending seawards a heavy flood often carries away down the stream 

 weak and spawned fish, but when migrating seawards it would appear that the 

 fish usually pass gradually into the sea. The migrating salmon fry or smolts keep 

 to the sides of the river, but having once arrived at the ocean would appear to 

 seek its depths. 



The food consumed by salmon is somewhat varied, for while living in the 

 ocean they appear to lay in a sufficient stock of fat around the stomach and coecal 

 appendages to last them when residing in fresh water, or at least until the 

 spawning season has passed. I have found the remains of sand-eels, Ammodytes, 

 herrings, Crustacea and echinodermata in their stomachs. Jardine remarked that 

 on the Sutherland shores they are often captured on haddock lines baited with 

 sand-eels. Thompson, in Ireland, also found these fish eating sand-eels, and that 

 they are occasionally taken in Dundrum Bay upon lines baited with pieces of 

 mackerel which were laid for mullet. Morrison records having captured salmon 

 within flood mark, some of which contained two, others three, full sized herrings. 

 In the British Museum are the remains of a gar-fish, Belone, taken out of a salmon 

 captured in fresh water, but evidently only lately from the sea. One of 24 lb. 

 being opened, two trout (size six to a pound) were found inside it (Fishing 

 Gazette, December 20th, 1879). Parnell remarks upon having discovered the 

 remains of some food in the lower intestines even when the stomach was empty. 

 As a rule very little food is found in those residing in fresh waters, while if in roe 

 they are almost invariably found to be quite empty. 



The young parr takes any bait with avidity, and at almost any time, even 

 when the trout refuses to rise, while their stomachs are often found gorged with 

 the larva of aquatic insects. Mr. Tegetmeier observed (Proc. Zool. Soc. 1868) 

 that the smolts which left the Stormontfields ponds in May that year were much 

 larger than those of the previous season, due to their diet having been changed 

 from boiled ox liver rubbed down to coarse powder. This season the aquatic weeds 

 in the ponds had become covered with Limnea peregra, on which they fed greedily 

 and to which the great increase in size was undoubtedly to be attributed. 



Fisheries. — As accurate statistics of what at present exist in the British Isles 

 are unobtainable and fancy has filled in what facts have not proved, I restrict 



* Gfinther observes that a salmon changing from salt to fresh water and vice versti several times 

 yearly, only occurs in rivers filling into the Moray Firth (Introduction, Study of Fish, p. 640). 



