CHARACTERISTIC DEEP-SEA TYPES. FISHES. 23 



Many surface fishes also descend to considerable depths. In 

 fact, the migration of our coast fishes is one of the most impor- 

 tant problems which the fisherman has to solve, and one of 

 which we as yet know but little. There seems to be no seri- 

 ous obstacle to extensive bathymetric movements' on the part of 

 fishes. The silver hake, which is abundant all summer long at 

 the surface on the New England coast, has been taken from 

 487 fathoms, and appears to live in September and October at 

 considerable depths off Southern New England. There is reason 

 to believe that the mackerel, menhaden, and the bluefish also go 

 down below the hundred-fathom line in winter. 



The fishes of the abyssal realm are very distinct from those 

 of the surface faunae. It is safe to say that there are more 

 genera common to the seas of Australia and North America than 

 to the littoral and abyssal faunae off the Atlantic coast of the 

 United States, excluding the pelagic types,- many of which 

 are cosmopolitan. Indeed, of the sixty or more genera which 

 have been dredged below 1,000 fathoms in any sea, only one 

 has been found in less than 200 fathoms on our own coast, and 

 four within the two hundred-fathom line in any sea, even in 

 polar regions. Of the same assemblage, only seven occur any- 

 where in less than 300 fathoms, and down to 500 fourteen are 

 added to the list. These fourteen genera represent ten fami- 

 lies. Out of the thirty-four family groups which are repre- 

 sented below 1,000 fathoms, or in mid-ocean beyond soundings, 

 only five are represented in any in-shore fauna, even in circum- 

 polar regions. 



We have now considered the composition of the abyssal 

 fauna, as found at the greatest depths. A glance at its upper 

 limits may also prove instructive ; we find below the hundred- 

 fathom line, and within the limit of 500 fathoms, a very hete- 

 rogeneous assemblage. Well-known surface species inhabit 

 at times water of considerable depths. The cod goes below 

 100 fathoms ; the halibut and the Newfoundland turbot go be- 

 low 300, and the haddock apparently to 500, on the New Eng- 

 land coast. Hake are also deep-sea lovers, being recorded at a 

 depth of over 304 fathoms. One of the species of Phycis (P. 

 regius) from 233 fathoms was discovered to be electric, giving 



