O.A. Grimm (1896), in his now classical monograph, "Kaspiysko Volzhskoye 

 Rybolovstvo" (Fishing the the Caspian and Volga), in analyzing the paths of 

 influence of petroleum on the "fish content" of this basin, wrote, "It is 

 quite probable that petroleum kills the fry of the Clupeidae family of fish 

 and others, which float on the top or accumulate near the bank in shoals". 

 Somewhat later, H. Clark and G. Adams (1913) concluded that one of the lead- 

 ing causes of the decrease in the population of whitefish was pollution of 

 the spawning grounds in the Great Lakes with industrial wastewater. How- 

 ever, experimental study of the age specifics of toxicoresistance of fish 

 began only comparatively recently. 



One of the first reports in this area is that of N.S. Stroganov and A.M. 

 Pazhitkov (1941). In experiments with eggs, larvae, fry and mature individ- 

 uals of perch, it was shown that the early stages of development are less 

 resistant to the ions of copper and ammonia than mature fish. Given equal 

 exposure, mature perch survived in solutions of copper 100 times more con- 

 centrated than the lethal concentration for fry. In experiments with am- 

 monia, the differ^ence was less striking, but still clearly indicated the 

 lower stability of embryos and perch larvae than that of mature fish. 



The high resistance of mature fish in comparison to larvae and fry for 

 heavy metal salts was noted by other authors as well (Sollman and Schweiger 

 1957; Cairns and Seheir 1957). However, in later works, materials have been 

 presented indicating that the stability of fish in the early stages of on- 

 togenesis is higher than that of mature individuals, or at least equal 

 (Mosevich, et al_. 1952; Wurtz-Arle 1959; Katz and Chadwick 1961; Vernidub 

 1962). For example, N.A. Mosevich, et^ al. (1952), in experiments with eggs, 

 larvae and first-year perch, establisheT"that the first-year fish were less 

 resistant to phenol than the eggs and larvae. Developing eggs and recently 

 hatched larvae were found to be more resistant than mature fish to the 

 pesticide andrin (Katz and Chadwick 1961). These data agree with the mate- 

 rials of Ye. A. Veselova, et al_. (1965), who studied the toxicity of still 

 another pesticide - hexachlorane - and concluded that developing eggs and 

 larvae of many species of fish (salmon, roach, bleak, perch, rock perch, 

 pike) are somewhat more stable than mature individuals. Finally, in a work 

 of D. Wurtz-Arle (1959) performed on developing eggs and fry of trout, it 

 was shown that their resistance to two detergents (sodium alkylsulfates) de- 

 creases with age. 



Thus, in the mid-1960's there were two mutually opposite points of view. 

 The proponents of one believed that "the most vulnerable stage of ontogene- 

 sis in fish for the effects of toxic substances is the stage of the larvae 

 and fry" (Stroganov and Pazhitkov 1941, p. 68), i.e., the toxicoresistance 

 increases with age. The other group of authors held the opposite point of 

 view, assuming that the resistance of fish to poisons decreases with age and 

 that it is highest in the early stages of ontogenesis. 



Analysis of the available literature data has allowed us (Lukyanenko 

 1967) to find the reasons for this contradiction. It was found that the 

 proponents of the idea of increased stability of fish in early stages of in- 

 dividual development based their ideas on data obtained in experiments with 

 organic poisons (phenols, synthetic detergents, pesticides). Researchers 



157 



