| Abstract: | The maximum egg mortality that a population can afford if itis not to wane, here labelled the affordable egg mortality,can be estimated from knowledge of life history traits, i.e.fecundity, development time, egg hatching time and post-eggmortality. Examination of changes in the affordable egg mort-alitywith variations in the life history traits yields two main conclusions:when development time is short, the affordable egg mortalityis maximized by reducing the egg hatching time, instead of bymaximizing fecundity. In contrast, when development time islong, or when post-egg mortality is high, the affordable eggmortality is maximized by a combination of low egg hatchingtime and very high fecundity, or by increasing the egg hatchingtime. For a growing population, the realized egg mortality shouldalways be less than the affordable mortality. This conditioncan be exploited to check the validity of measured mortalitycoefficients, and is illustrated with two examples from publishedfield studies on marine copepods. These examples reveal thatfor populations in temperate environments that typically displaygrowth in the winter and spring months, high egg losses (>>1 day–1) cannot be sustained unless recruits are suppliedfrom outside the population. |
