Notes and Memoranda

Extract

TheBulletin of the United States Fish Commission for 1889 contains a report upon a physical investigation of the waters off the southern coast of New England in the schooner Grampus during the summer of 1889, by Professor W. Libbey of Princeton College. This forms the first instalment of a series which promises to throw much light on the relations of temperature and salinity to the distribution of fishes and their food, and was itself directly suggested by researches upon the shad and the menhaden.

The observations cover the area between lat. 39° N. and lat. 41° 10′ N., and long. 70° W. to long. 71° 30′ W., soundings being obtained as nearly as possible every 10′ along lines 10′ apart. At each station a very complete series of temperature observations was made, and samples were collected at surface, bottom, and in the deeper soundings at an intermediate point. The specific gravities of these samples were determined by means of a Kilgard salMBImeter.

The temperature profiles along meridians of longitude are of great interest, extending as they do from near the coast over the edge of the continental plateau into deep water. The bathy-isothermal line of 50° F. shows a remarkable curvature off the continental platform, which the report says “would seem to point to a mechanical intrusion of cold water from the surface of the continental platform.” The conclusion is confirmed by the specific gravity observations; and the report goes on to say, “The existence of this body of warm water off the continental edge may offer an explanation of the richness of this particular spot in all forms of marine life, as shown by the successful dredging of the Albatross upon it.”