244 PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 



ON THE DESTRUCTION OF FISH IN THE VICINITY OF THE TORTUGAS 

 DURING THE MONTHS OF SEPTEMBER AND OCTOBER, 1878. 



By JLieut. J. P. JEFFERSON, E>i\ JOSEPH Y. PORTER, and 



THOUIAS MOORE. 



The following information, relative to the dying offish in the Gulf of 

 Mexico during the mouth of September last, will be found of much 

 interest, as bearing upon the sudden destruction in large numbers of 

 marine animals, and their accumulation in geological strata. — Editor. 



Fort Jefferson, Dry Tortugas, Fla., 



October 16, 187S. 



I have the honor to enclose herewith the skin of a fish* which was 

 found on the beach here. I send it because many old fishermen say that 

 they never before saw one like it. Some five or six were picked up 

 from a multitude of other fish ; aud to report this great mortality 

 among them is my principal reason for addressing you. Some three or 

 four weeks ago, the fishing-smacks over in Florida Bay lost about all 

 their fish in their wells, aud attributed it to fresh water, which they sup- 

 posed had from some cause or other come down in great volume from 

 the mainland. On the 9th instant, the sailing-vessel which connects us 

 with Key West met water of a dark color about midway between 

 here and there, but saw no dead fish. On her return, on the night 

 of the 11th, she struck it oft* Rebecca Shoals, about 25 miles east 

 of here, and found it extending some 10 miles out in the Gulf. That 

 same night it came down upon us here, and the next morning the beach 

 and surface of the water, as far as the eye could reach, were covered with 

 dead fish. The appearance of the water had entirely changed ; instead 

 of the usual clear blue or green, it was very dark, like cypress water, 

 and when viewed at depths over 10 feet, was almost black, precisely 

 like the Saint John's River. We could not perceive any change in the 

 saltness of the water but not having any other means of determining 

 this, had to depend upon taste. There was no appreciable change in 

 temperature. From the fact that almost all the fish that first came 

 ashore were small and of such varieties as frequent shoal water, I infer 

 that the dark water must have been of less density than the sea ; still, 

 great numbers of "grouper" have been seen, and these are generally 

 found in 3 or 4 fathoms, I believe. The destruction must have been 

 very great, for here, on a key containing but a few acres, and with a 

 very limited extent of beach, we have buried at least twenty cart-loads: 

 they have come ashore in such numbers that it has been a serious mat- 

 ter how to dispose of them. 



"This on examination by Professor Gill was pronounced to be Aulosloma coloratum. 



