MORTALITY OF FISHES, WEST COAST OF FLORIDA. 



21 



It is noteworthy that the water in which the filefish was seen to die 

 was of the highest salinity and lowest alkalinity found. Otherwise, 

 there seem to be no factors showing any striking correlation. 



The following are the results of such determinations as were made : 



Alkalinity and Salinity. 



Fraction | 



of normal Salinity. 

 alkaU. 



1916. 



Nov. 19.... 

 Nov. 13.... 



Nov. 16.... 

 Nov. 19 . . . 



Nov. 14.... 

 Do.... 



Nov. 15.... 



Prior to 



Nov. 13. 



Nov. 19.... 



Nov. 15... 



Nov. 19 . . . 

 Mean 



. 00282 

 .00277 



.00272 

 . 00261 



.00236 

 . 00276 



'/oo 



29.94 



32.81 



31.52 

 30.61 



32.96 



33.10 

 30.97 

 32.43 



31.98 



In shallovr water at Bailey's wharf, Sanibel, where fileflsh died. 

 Sanibel post-office wharf; surface; day before storm; sealed in glass; 



76.5° F. 

 Sanibel post-office wharf; surface; day after storm; 65° F.; very low tide. 

 Bailey's wharf, Sanibel; 2 fathoms (bottom); 50 feet from pomt where 



fileflsh died; live mangrove snapper.s. 

 One-half mile from Point Ybel Light. San Carlos Pass; 75° F. 

 One and one-half miles from Point Ybel Light, San Carlos Pass; sample 



from surface; water 2 fathoms: 72.4° F. 

 Place where mullet died, shallow water of Tarpon Bay; described by 



fisherman; H hours before storm; 75.3° F.; live conchs; porpoises in 



water. 

 Specimens submitted by West Coast Fish Co., Kitchins Island, Pine 



Island Soimd. 

 Bottom (2 fatlioms) off Point Ybel Light wharf, Sanibel, IJ miles from 



point where filefish died; 65.4° F. 

 Near (Uilf mouth, Blind Pass; rising tide; surface sample; 2^ fathoms 



water; 20 minutes before storm broke; 75.8° F.; probably pure Gulf 



water. 

 Surf water on Gulf Beach. 



OTHER MORTALITIES DUE TO OBSCURE CAUSES. 



Other mortalities have occurred in different parts of the world, due 

 to obscure causes. Austin H. Clark (1903) observed a mortality of 

 fislies on the coast of Venezuela, which seems similar to that off the 

 Florida coast. Nordenskiold (1882) noted dead Gadus polaris in the 

 Silierian Polar Sea, which he supposes to have been killed by an in- 

 sufficiency of oxygen, under the ice, where the fish w^ere confined. 

 Cold has unquestionably brought about the death of fishes in many 

 parts of the world." 



Gilchrist (1914) cites numerous mortalities on the South African 

 coast in addition to those already cited, ascribed to Peridinium, 

 Noctiluca^ and diatoms, but altogether without satisfactory explana- 

 tion. One, however, deserves particular mention. In this case (which 

 repeats itself annually at Knysna) there was a narrow streak of 

 yellowish water extending along the coast for miles, of a temperature 

 nbout 10° F. lower than the blue ocean water farther out, which was 

 clearly marked oft' from the yellowish water. The author attempts to 

 explain this by the meeting off this coast of the Mozambique (warm) 



a On Feb. 2 and 3, 1917, a " freeze " occurred on both coasts of Florida, killing thou- 

 sands of fishes. This cold wave is described by R. H. Fitch in a forthcoming paper of the 

 Weather Bureau. 



99805°— 19 23 



