86 ME. r. DAT ON THE MABHSTE FAUNA 



Some suppose that this fish is not, strictly speaking, migratory — 

 that is, that it does not travel comparatively far from the locality 

 in which it was hatched, reared, and came to maturity, but simply 

 changes from shallow to deep water, in accordance with tempe- 

 rature and the supply of food — one proof advanced being that 

 certain definite varieties are present in certain waters. Where 

 they conceal themselves is certainly remarkable. Thus along the 

 Devonshire and south-west coast of England, Mr. Dunn observes 

 that should a gale spring up numbers are taken in nets pur- 

 posely anchored parallel to the shore, while they are meshed on 

 the land side, and this in localities which had been unsuccessfully 

 swept by seines and nets a very short time previously. 



That herrings, in common with other species of the herring 

 family, will occasionally disappear from one locality, sometimes 

 reappearing in another, is well known. I have observed it as 

 occurring among the oil-sardines of India {Olupea longiceps) ; and 

 this has taken place in years when the fishing was very little 

 prosecuted. From 1690 to 1709 a very extensive herring 

 fishery existed at Cromarty ; about the latter year an immense 

 shoal was driven ashore near the tovni ; the remainder left the 

 vicinity in a single night ; and for upwards of half a century 

 no shoals reappeared. 



The two main objects of migration would appear to be for the 

 purpose of seeking some locality where spawn may be safely 

 deposited and the species continued, or else a search for food in 

 order to maintain the growth and existence of the individual. 

 But it would seem that fish may seek new ground when that they 

 usually reside on has become unsuited to them from any cause, as 

 absence of food or even their constant capture by incessant 

 netting. If having selected waters further from the shore than 

 formerly, the spawn were deposited and bred there, it does not 

 seem unreasonable to suppose that the progeny would locate 

 themselves where they were reared. In time, perhaps, this new 

 location may be found unsuited, and the shoal may return to the 

 spot they first inhabited, and where possibly a more abundant 

 supply of surface-food may exist. 



At Wick, upon the north-east coast of Scotland, the largest 

 race usually arrives with the new year, remaining until about 

 March, and then disappears. The next herrings come in May or 

 June in the shape of a few small ones of little value as food, 



