Parent-egg-progeny relationships in teleost fishes: an energetics perspective

Age-related variations in chemical composition of egg matter were found in females in some studies, but they do not seem to be a universal phenomenon. In contrast, egg size can be well predicted from female age. The relationship has a parabolic shape, but the predicted size decrease of eggs from old females has not always been documented. Female size is an important contributor to egg size, both at intra- and inter-specific levels. Dependence of fecundity on body size has usually been described by a power function. A trade-off between egg number and size is considered in light of life history strategies. During a spawning season egg size may differ between successive batches, but lack of effects of egg batch sequence was reported in some studies. In yolk-feeding fish three discrete periods of elevated mortality are typically observed: shortly after egg activation, during hatching, and at final yolk resorption. The positive relationships between female size, egg size and offspring size/resistance to starvation and predation are a key pathway in parent-egg-progeny relationships. Both maternal and paternal effects contribute to the total survival of offspring, but they operate in different ways and at different times. In contrast to the importance of female size, no paternal size effects were revealed, but density and motility of spermatozoans were decisive. Typically, paternal effects diminish earlier in ontogeny. Major factors governing embryonic survival (fertilisation success and hatching success) differ from factors to which starvation mortality of yolk-feeding larvae is related. Embryonic survival is affected by female age via egg matter composition, by egg ripeness and paternal factors such as sperm density and motility. In contrast, starvation mortality of yolk-feeding larvae depends largely on female attributes (age, size and fecundity) via egg size, and, in some batch spawners, on egg batch sequence. Among teleost species egg size varies across a wide range (from 0.3 to 85-90 mm in diameter). Species that spawn large eggs are relatively rare. Caloric value of egg dry matter varies within a narrow range of 20-30 J mg(-1). Ecosystem and evolutionary components, and reproductive style are factors that contribute to egg endowment and yolk quality. During the last decade considerable progress was made in the methodology and understanding of paternal effect on progeny performance in fishes. This paper reviews these of parent-egg-progeny relationships.