Relationship between filial cannibalism, egg energetic content and parental condition in the flagfish

Filial cannibalism (the consumption of one's own offspring) is prevalent in a range of animals and is thought to represent an adaptive strategy in which parents consume some offspring to increase their current and/or future reproductive success. Relatively little is known about the relationship between parental condition, general offspring quality and filial cannibalism. I examined the relationship between filial cannibalism, paternal and maternal size and condition, and egg energetic content in the flagfish, a species in which males provide parental care and practise filial cannibalism of eggs. Males were more likely to consume their entire clutch when egg energetic content was relatively high and when the clutch was spawned by relatively large females. In contrast, there was a negative relationship between per-egg energetic content and the number of eggs consumed for cases of partial-clutch cannibalism. Similarly, maternal size was negatively correlated with the proportion and number of eggs consumed for cases of partial-clutch cannibalism. Both maternal size and egg energetic content have been previously correlated with posthatching survival in a range of fishes. Thus, for cases of whole-clutch cannibalism, male flagfish appear to consume their high-quality offspring, whereas for cases of partial-clutch cannibalism, males preferentially consume lower-quality offspring. In addition, smaller males netted a greater amount of energy through partial-clutch cannibalism than did larger males, suggesting that male size potentially influences cannibalism in the flagfish.