NATURAL HISTORY OF THE BAY SCALLOP 
617 
section, which includes southern Core Sound, to 13-16.6 parts per mille 7 on February 
7. Scallops are reported to have been then in very poor condition. In March scal- 
SA UNITY 
o/oo 
Figure 29. — Daily salinities at Pivers Island through autumnal periods of extreme scallop destruction (1924), moderate 
mortality of adults (1928), and good survival (1926). (Based on one hydrometer reading daily, corrected for tem- 
perature but instrumental error not known.) See Table 9 
lops were not being' taken there commercially, but whether because they had all 
been caught or because of mortality in situ is not known. Tables 8 and 9 and Figures 
30 and 31, show noticeably reduced 
salinities at Pivers Island early in 
1924 and 1925. Because scallops 
were generally abundant in the sum- 
mer of 1924 and at Pivers Island 
in 1925, it is evident that this low 
salinity caused no extreme mortal- 
ity, at least among the young. In 
February and March, 1926, salinities 
as low as 20 parts per mille were 
attained. In January, following the 
severe cold of late December, there 
was noticeable mortality among 
adult scallops, but not in February or March. In October, 1928, as a result of unusual 
inland rains in September, observed salinity at Pivers Island became as low as about 
19 parts per mille (18.6 parts per mille as calculated from routine hydrometer read- 
ings). This freshening was accompanied or followed by a considerable mortality 
among adult scallops at Pivers Island and other places in Beaufort Harbor. In 
Newport River the destruction was so great as to cause the general abandonment 
of its scallop grounds in the ensuing commercial season. Just how fresh the water 
over these grounds became is not known. However, near the mouth of the canalized 
connection with Neuse River and within the extreme limits of scallop extension, a 
salinity of 4.8 parts per mille was found. In Core Sound scallops survived salinities 
at least as low as 16.2 parts per mille (at Marshallberg) although in poor condition and 
perhaps with considerable delayed mortality. 
7 These figures for total salinity are based on data expressed as NaCl kindly furnished with other information by Dr. J. J. 
McManus, chief, Savannah station; Food, Drug, and Insecticide Administration; United States Department of Agriculture. 
The analytical work in this instance was done by James O. Clarke of the Food, Drug, and Insecticide Administration. 
°/co 
7 \~ 
I ... 3 ... 10 . ./O' . <0 .2S....3C., ■} . .3....n...l3... 29 
JANUARY F Z B RUARY 
Figure 30. — Daily salinities through a winter period (1925) with low 
salinities which produced no noticeable mortality and certainly 
spared sufficient young scallops for a good crop the succeeding 
winter (based on one hydrometer reading daily corrected for 
temperature but instrumental error not known) 
