872 MANUAL OF MODERN FAllKIERY. 



on their way to the sea, which may cause the ova to be 

 hatched sooner. This idea seems to be borne out by what 

 takes place in two Scottish rivers, namely, the Oikel and 

 Shin, in Sutherlandshh'e. The former of these is situated 

 on the border of tlie county, and takes its rise in a small 

 alpine lake, a,bout half a mile in breadth : the Shin is a tri- 

 butary of the Oikel, and has its origin from Loch-Shin, 

 wdiich is large and deep, and is connected with a series of 

 other deep lochs. This joins the Oikel, about five miles from 

 its mouth. Early in the spring all the salmon entering the 

 common mouth of these rivers invariably turn up the Shin, 

 returning to their own warmer stream, while very few pursue 

 their course up the Oikel until a much later period. 



The same kind of evidence is furnished by Dr. Heysham, 

 in his " Catalogue of Cumberland Animals." He says, 

 " The salmon is plentiful in most of our rivers, in all of 

 which they spawn ; but they evidently prefer, during the 

 winter and spring, the Eden to the Esk, the Caldew, or the 

 Peterel. Although the Esk and the Eden pour out their 

 w^aters into the same estuary, and are only separated at the 

 mouths by a short point of land, yet there is scarcely an in- 

 stance of a new salmon ever entering the former until the 

 middle of April or beginning of May. The fishermen account 

 for this curious fact from the difierent temperature of these 

 two rivers ; the water of the Eden, they allege, being consider- 

 ably warmer than the water of the Esk ; which is not alto- 

 gether improbable, for the bed of the Esk is not only more 

 stony and rocky than the Eden, but is likewise broader and 

 the stream more shallow, consequently, its waters must be 

 somewhat colder in the winter season. It is an undoubted 

 fact that snow-water prevents salmon from running up even 

 in the Eden : it is probable this circumstance may have consi- 

 derable efiect in preventing them from entering the Esk 



