Fecundity refers to:
Fecundity is an organism’s potential reproductive output under specified physiological and environmental conditions. It describes reproductive capacity, such as the possible number of eggs, seeds, or offspring that an individual can produce, rather than the number that is actually produced and survives. Fertility or realized reproductive performance is often used for the observed production of viable offspring, although terminology varies among disciplines. Ecologists distinguish potential from realized output because nutrition, mate availability, age, disease, social status, and environmental stress can prevent an organism from expressing its full capacity. Fecundity commonly appears in life tables as age-specific maternity, where it helps determine net reproductive rate and population growth. For example, a fish may produce thousands of eggs and therefore have high fecundity, yet recruit few juveniles because fertilization and early survival are low. Mortality is a separate demographic rate that removes individuals. The central principle is that fecundity sets an upper reproductive capacity, while ecological conditions determine how much of that capacity becomes actual recruitment.
Ref: Ecology: Concepts and Applications, Molles, 9th Ed., Ch. 11