24 MIGRATIONS OP HERRINGS AND SALMON. 



open sea ; but they then come into shallower water, and seek a 

 convenient place for laying their eggs, where they remain until 

 towards the month of February. The older Herrings deposit 

 their spawn the first, and the younger ones afterwards; but 

 temperature and other circumstances also appear to have some 

 influence on this phenomenon ; for in particular localities, we 

 find eggs during nearly the whole year. After this period they 

 are thin and but little esteemed; fishermen then call them 

 " shotten herrings." Their multiplication is prodigious ; there 

 have been found more than sixty thousand eggs in the abdomen 

 of one single female of moderate size. We are told that their 

 spawn sometimes covers the surface of the sea for a great extent, 

 and at a distance appears very much as if saw-dust had been 

 spread tbere. Very little is known of these fish at an early 

 period. 



548. The Pilchard, the Mackerel, the Tunny, and the 

 Anchovy, are also Fish of passage, which periodically visit the 

 coasts, and give rise there to important fisheries. The Salmon 

 is equally remarkable for its voyages : it inhabits all the arctic 

 seas, and every spring it enters the rivers in large numbers, and 

 ascends nearly to their source. In these migrations the Salmon 

 follow a regular order ; forming into two long files united in 

 front, and conducted by the largest female, who commences the 

 march, whilst the smaller males form the rear-guard. These 

 troops generally swim with a great noise in the middle of the 

 stream, and near the surface of the water, if the temperature is 

 mild, but nearer the bottom if the heat is great. In general 

 the Salmon advance slowly and by leaping ; but if some danger 

 appears to threaten them, the rapidity of their swimming is so 

 great, that the eye can hardly follow them. If a dyke or a 

 cascade opposes their progress, they make the greatest efforts to 

 overcome it. By supporting themselves against a rock, and 

 violently bending their body in a bow, they throw themselves 

 out of the water, and jump sometimes to a height of from 10 to 

 16 feet into the air, so as to fall again clear of the obstacle 

 which impeded them. The Salmon thus ascend rivers nearly to 

 their source ; and then seek in the small streams and quiet places a 



