204 SALT-WATER FISHES 



is here merely necessary to state that it is now known to 

 consist (with various commercial adulteration) of the young of 

 the herring and sprat in proportions that vary according to the 

 season, and not, as was formerly held, to be the young of the 

 bleak, as stated by Pennant, or of the shad, as insisted by 

 Donovan. In June and July the whitebait of the Thames 

 estuary contains about 80 per cent, young herrings ; in 

 •February and March about 90 per cent young sprats ; at all 

 times young sand-eels, gurnards, pipe-fish, and even shrimps. 



The migrations of the herring in our seas have been studied 

 to much the same extent as those of the mackerel, and in both 

 cases the movements of the shoals are now regarded as much 

 less extensive than would be gathered from the circumstantial 

 accounts given by earlier writers. The modern view — which 

 further investigations of the subject, particularly on the basis 

 of the study of distinct races as pursued by Dr. Heincke and 

 by some of our own biologists, will either confirm or otherwise — 

 is that the fish leave or approach the coast, moving to and 

 from the deeper water of the northern seas, chiefly for the 

 purpose of procuring fresh food-supplies. These wanderings 

 do not appear, however, to have taken the fish through the 

 Straits of Gibraltar, for they are regarded as wanting in the 

 Mediterranean. Now and then the summer herring mass so 

 thick on favourite feeding-grounds on our coasts that the water is 

 thickened by their excreta, and many other fishes shelter in this 

 turbid area of the sea, where their enemies are unable to find 

 them. Both pilchards, however, and mackerel, so Dunn used 

 to say, keep away from these feeding shoals. He was also of 

 opinion that herrings displayed above most other fishes what he 

 called a sixth sense, for it was always observed that they were the 

 first to leave the inshore grounds on the approach of a coming 

 storm, and from the fact of their always moving away to 

 leeward, it looked as if they even knew the direction from 

 which it was blowing. 



The I'ilchard (C pilchardus) has, as before mentioned, 



