Jackson (1956) demonstrated that pellets of 
sodium hydroxide dropped in the nests of sun- 
fish would kill eggs and fry. In 1958, Bridges 
reported on the efficacy of sodium cyanide as 
a fish poison, It is toxic to fish at low con- 
centrations, persists only a short time in 
water, and first anesthetizes fish before kill- 
ing them, Fish may survive if removed 
promptly to fresh water. The compound, how- 
ever, is highly dangerous to humans, Also in 
1958, Applegate et al. related the results of 
research to find selective toxicants for the 
larvae of sea lampreys. The developmen: of 
TFM (3-trifluoromethyl-4-nitrophenol)as a 
selective larvicide was a long step toward the 
control of sea lampreys in the Great Lakes by 
the United States and Canada (Applegate etal., 
1961), It also stimulated increasing investiga- 
tion to find and develop better general and 
selective toxicants for fish. 
Saponin, a glucoside extracted from plants, 
was tested by Tang (1961) in Taiwan as a 
selective control for predaceous fish in in- 
tensively cultured shrimp ponds. Fish were 
successfully eliminated, but more work is 
needed to determine the effects of saponin on 
the food and the growth of shrimp. A malathion- 
dibrom mixture was introduced with some 
success in 1962 as a relatively selective con- 
trol for certain sunfishes (Grice, 1962), In 
step with the times, investigations by MacPhee 
(1963) center on the specific toxicants for fish 
sperm and ova. 
In 1963, Derse and Strong reported on the 
toxicity of antimycin to fish and indicated its 
promise as a fishery tool. Subsequently, re- 
search at the Fish Control Laboratories at 
LaCrosse, Wis., and Warm Springs, Ga., has 
been centered on this antibiotic product of 
Streptomyces, It appears effective against a 
wide variety of fish species and sizes, eggs to 
adults, in very small concentrations. It is 
easily applied; there is little evidence of 
hazard to fish food organisms; it is effective 
over a wide range of temperatures; and it 
degrades rapidly in water (Walker, et al., 
1964), The product is currently undergoing 
thorough testing in the laboratory and field. 
In his critique of the need and use for fish 
poisons, Miller (1950) pointed out a general 
lack of follow-up studies or controlled ex- 
perimentation with toxicants. He complained 
that the literature is limited on data on the 
31 
completeness of kills, fish recovered, and 
rapidity of repopulation of undesirable species. 
There is also a dearth of information about 
the hazards involved, Until recently, the ap- 
plication of toxicants for fishery management 
often preceded research on their side effects. 
This situation, fortunately, is now being rem- 
edied through the efforts of formal investiga- 
tions on chemicals as tools in fishery man- 
agement (Hooper et al., 1964; Lennon and 
Walker, 1964), 
FUTURE TRENDS 
Increased public awareness of fish and 
wildlife values, both economic and esthetic, 
has resulted in considerable opposition to the 
continued use of broad-spectrum lethal agents 
for many kinds of pest control. As stated by 
Baldwin (1964), ''There is a growing concern, 
coupled with positive action, for the preserva- 
tion of all forms of plant and animal life." 
This recognition along with mounting public 
interest in the effects of toxic chemicals on 
human health are, in large measure, due to 
the widespread publicity concerning pesticides 
aroused by publication of the book "Silent 
Spring" in 1962 by the late Rachel Carson. 
The next year this was followed by a report 
on the "Use of Pesticides" by the President's 
Science Advisory Committee. The recom- 
mendations in this report have had a strong 
effect on numerous kinds of pesticidal re- 
search during the current year. 
The future role of chemicals in the control 
of vertebrate pests will be increasingly de- 
pendent on new knowledge acquired through 
the combined efforts of chemists and biolo- 
gists. Priority is being given to nonlethal 
chemical methods for the management of fish 
and wildlife populations. Although the work 
includes a continuing and expanding search 
for selective lethal agents, their utility will 
be contingent upon their degree of specificity 
for target species and nonpersistence in the 
environment. 
Over the millions of years that multicelled 
organisms have been evolving, they have de- 
veloped a fantastic capability within them- 
selves to quickly synthesize complex chemical 
compounds, each having a special arrangement 
for one specific task. Among the vertebrates 
