HISTORY OF THE AMERICAN MENHADEN. 55 



1874, December in Cbarlestoji averaged 48o.8; in 1875, January aver- 

 aged 500.2. 



The movements of the menhaden in this region have not been 

 observed, but since in the north it is not more hardy than the shad, and 

 since the shad do not venture into the Georgia and Carolina rivers in 

 December, it is sale to predict that the habits of the menhaden are 

 similar. 



Jacksonville, Fla., is the only point on the east coast from which there 

 are observations showing a temperature unformily above 51°, and here 

 the menhaden remain throughout the winter. 



Maximum limits of temperature. — On the coast of Eastern Maine wo are 

 told that the menhaden schools keep passing to the eastward until about 

 the middle of July, when their impetus is apparently checked and their 

 movements for thirty or forty days seem to be local only. During this 

 period the temperature at Portland ranges from 60° to 70°, this being 

 the height of mid-summer. The monthly means for July and August, 

 187G, were 66^.7 and 63o.9. The same months at New London are 

 placed at 73° and 73o.3 ; at Norfolk, 840.1 and 780.3. Wilmington, 

 Charleston, and Savannah do not range much above Norfolk ; June, 

 July, and August at Jacksonville average above 85°, and we have no 

 satisfactory evidence that the menhaden are seen there in mid-summer. 

 At Key West the lowest monthly mean is December, at G6o 4, in an 

 unusually cold winter. 



Preferred range of temperature. — These facts appear to indicate that 

 under ordinary circumstances the menhaden prefers a temperature of 

 60O to 70° Fahrenheit. When the rising temperature of spring haspassed 

 the limit of 50° to 51° the fish are certain to appear, and when the fall- 

 ing temperature of autumn reaches that point their departure is equally 

 sure, though a few individuals may linger in waters not congenial to 

 them. The opposite limit seems to be marked by the line of 80° or per- 

 haps 750. An easterly or northerly wind, lowering temporarily the sur- 

 face temperature, causes the schools to sink below the surface, as is shown 

 in paragraph 95- The chill of night also drives them down. 



These conclusions are not to be regarded as final. The movements 

 of the fish about Cape Hatteras are very puzzling and need to be inter- 

 preted by a series of careful temperature observations. 



It is a well-established fact that the summer of 1877 was not so warm 

 as that of the preceding year. It is also known that the catch of men- 

 haden in Maine for that year was much smaller than in 187G, when it 

 was unusually large. There may be a connection between these circum- 

 stances, though the observations of water temperatures at my disposal 

 are not sufficient to warrant decided generalization. The means for the 

 summer months of 1876 were, at Eastport, 450.5; at Portland, 57=^.9 ; at 

 Wood's Holl, 70O.4 ; at New London, 08° ; at Norfolk, 780.7. The corre- 

 sponding means for 1877 were, at Eastport, 420.8; Portland, 570.6; Wood's 

 Holl, 670.7 ; New London, 66o.9 ; and Norfolk, 77^.2. The summer of 



