HISTORY OF THE AMERICAN MENHADEN. G7 



kalleraglitz or American tnrbot {Reinhardtkis Mppoplossoidcs) is taken 

 "with books, in the dead of winter, under the floe ice of North Greenland 

 at a depth of 300 fathoms; in South Greenland, on the oceanic banks, at 

 CO and 80 fa'. horns; and at Fortune Bay, Newfoundland, it is captured in 

 the shore herring-seines at the same season. 



So long as the menhaden can avoid the extremes of temperature which 

 they so carefully avoid in the summer by seeking congenial warmtb 

 in the ocean strata under the Gulf Stream, need we suppose that they 

 will plunge into the colder strata below ? 



(2.) It involves less radical changes than hibernation in the habits of 

 the fishes. Some fishes, like the mud-minnow ( Umhralimi) of theFjastem 

 United States, are peculiarly adapted for life in the mud ; others, such, 

 as the " compound breathers " [Lahyrinthici) of India, are said to respire 

 with ease with their heads covered by liquid mud. Such fishes, how- 

 ever, are totally different in organization from the free-swimming spe- 

 cies of the open seas. 'All free swimmers are especially heedful to avoid 

 contact with the bottom. This is especially so in the case of the herring' 

 family, of AAiiich the menhaden is a member. They are provided usually 

 with deciduous scales, and never suffer themselves to come in contact 

 with the bottom. If one of the herring or mackerel tribe is placed in 

 an aquarium, it will be noticed that it keeps itself always free from the 

 bottom. Other fishes in the same tank, such as the sea-bass, tautog, or 

 king-fish, will be seen to rest on the bottom, and even to take refuge 

 under the stones. 



It is improbable that mackerel ever voluntarily sink into the mud of 

 the ocean bottom ; still more so in the case of the menhaden. 



(3.) It accounts better than the other theories for the early appear- 

 ance of the fish in the spring. 



Admitting the possibility of a winter's sojourn in the mud, we arc 

 met by a difficulty when we try to account for the prompt appearance 

 of the fishes in the spring. The deeper strata of the ocean are now 

 known to preserve throughout the year the uniibrm temperature of 22° 

 to 40°. The fish, once mummified in the depths of the ocean, would 

 remain so forever, unless they possess powers unknown to exist in other 

 animals. 



On the other hand, if we suppose the fish to be swimming in the strata 

 of mid-ocean, we know that they are in just the position to be suscepti- 

 ble to all the daily variations of temperature. Following, with the 

 advance of the season, the inward curving of the Gulf Stream, the warm 

 strata below it gradually ajjproach the shore. The schools of fish are 

 thus enabled gradually to draw nearer to the coast line, and when the 

 strata of 50° to 55° in temi)erature touch the coast the menhaden are at 

 hand. 



(4.) It explains, as well as the hibernation theory and better than the 

 migration theory, the peculiarity of the schools at difterent localities 

 along the coast. This was discussed in paragraph 88. 



