in an increase in the biomass of the older age groups. The principle of 

 maximum increase in the population and survival rate of juveniles and 

 methods of its realization have been suggested for the conduct of 

 mariculture of a number of species of mollusks in waters of the Soviet 

 Union (Golikov, Scarlato, 1970). 



In a steady population with a regular decrease in the number of 

 individuls as they grow, growth production of each generation is always 

 greater than the supporting production, due to the predominance of the 

 numbers of individuals in the younger age groups. If the steady-state 

 condition is disrupted in the direction of increasing the population of 

 the younger age groups, positive development of the population occurs 

 until the relationships between population and biomass of the various 

 generations achieve equilibrium at the new level and the relationship 

 between Pg and P^ is restored. Conversely, with a significant decrease 

 in the supplementation of juveniles, an increase is observed in the 

 share of supporting production, which may indicate that degradation of 

 the population is beginning. In those cases when supplementation of the 

 population is severely limited, supporting production may become equal 

 to growth production or even exceed it. In this case, one can expect 

 severe and extended depression or even disappearance of the 

 population. Actually, when supplementation of a population is reduced, 

 after a certain period of time has elapsed, a decrease occurs in the 

 number of producers, which, with a fixed level of elimination, causes a 

 still greater decrease in supplementation. A similar effect can be 

 observed in the case of a direct and sharp decrease in the population of 

 sexually mature individuals, leading to a significant decrease in the 

 effectiveness of spawning, for example, due to excessive fishing of 

 producer or sudden or unfavorable changes in the environment, usually 

 occurring along the edges of areas of distribution. A decrease in the 

 relative fraction of juveniles in the composition of these edge 

 populations of a species may frequently result from a sudden decrease in 

 the duration of temperatures favorable for breeding (Hutchins, 1947; 

 Golikov, Scarlato, 1973), which may even lead to total absence of 

 spawning in particularly unfavorable years. One result of this is a 

 decrease, at first in abiotic (Kinne, 1963), then in biotic potential of 

 the edge populations and a decrease in their growth production to the 

 level of the supporting production, or even below it. 



At the boundaries of populations, the supporting production 

 apparently usully exceeds the growth production, which is one of the 

 mechanisms of limiting the area of distribution of a population. For 

 example, this phenomenon was demonstrated for a population of the 

 bivalve mollusks Nuculana pernula in Terpeniye Bay in the Sea of Okhotsk 

 (Tabunkov, 1974). Extensive information on the dynamics of the 

 population indicates that, given significant changes in the structure of 

 a population, the inertia of its development is very high and may 

 require many years for stabilization, or may result in cyclical changes. 



The fact that the supporting portion of production is calculated 

 regardles of whether the population is steady or not allows us to assume 

 that the Pq/Pc ratio can serve as an indicator of instability of a 

 population and of the direction of its development (positive or 



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