
SEPTEMBER 1), CREEK MOUTH; Haul With Vu" Mesh Seine 
majalis 1-3/8" ~ 4-7/8" 
71 Killifish F. heteroclitus and F. 
9 Silverside “Menidia menidia aoa. : = Ul/ 
Weakfish Cynoscion regalis 2-1/8" - 3-1/8" 
3 Mullet Mugil c cephalus 3-3; /bt ~ 5-1/2" 
1 Menhaden Brevoortia tyrannus -1/)" 
1 Fluke Paralichthys dentatus l1-1/2" 
1 Goby species of Gobiidae not determined 1-5/8" 
Fish regularly enter or leave the creek and ditch systems with 
daily tidal currents. Only during the higher tides are they able to enter 
and leave the pools. In periods of such high water, fish populations in 
pools fluctuate greatly. This was demonstrated during three consecutive 
days when fish in a certain pool were present, absent, and then relatively 
abundant. 
Methods of Study 
Preliminary seining of fish from ponds indicated that this method 
would not be practical in appraising DDT mortality. Many fish were killed 
in these operations, and, in addition, it appeared almost impossible to 
capture all the fish in the ponds. For these reasons, seining of ponds was 
abandoned as a principal procedure. Instead, studies of fish mortality 
were based on: (1) general observations of fish abundance and activity 
before and after sprayings, (2) counts made within screen barriers set in 
creek channels, and (3) the use of caged fish. 
General Observations 
Seventeen hours after the first spraying in the 1.6 area dead 
fish were strewn liberally over creek sides and bottoms. Many others were 
seen floating in the slow ebb current of the creek. Observations of ditches 
revealed numbers of dead fish and no live ones although some fish normally 
remain when there is sufficient water. Nearly complete mortality occurred 
in shallow tide pools while in deeper pools it was somewhat less. Small 
fish less than 1-1/2" long made up the majority of the kill although a 
number of larger individuals up to 3" in length also succumbed. Fundulus 
killifish proved to be the predominant victims everywhere. Gulls were 
observed scavenging on a large scale. By the third day after spraying 
the evidences of death had largely disappeared. Gulls had aided in cleaning 
out dead fish from the tide pools and waterways, and water currents undoubt- 
edly had removed many of the floating carcasses from ditches and creeks. 
By the fifth day after spraying, not one dead fish could be seen anywhere 
in the area, 
Results of the second spraying on the 1.6 area were similar to 
the first. Mortalities in pools appeared as great as previously but the 
effects in creeks and ditches seemed less. Again, by the fifth day after 
Spraying, all evidence of dead fish had been removed. 
