Larvae need to orient themselves soon after hatching to increase their chance to find any reef or to come back to their home reef. This notion of 'larval homing behavior' is a new concept, but it makes sense when compared to other essential larval developmental traits such as first feeding and swimming.

If early fish larvae can sense their way home, we were certainly missing an important component in current bio-physical models that would change predictions of marine population connectivity.

critical period
The team used Hjort's "critical period" hypothesis, which says that fish recruitment variability is driven by the fate of the earliest larval stages, and that food and "aberrant drift" are the main factors contributing to the survivorship during this early phase.

According to this hypothesis, the proportion of survivors during this "critical" larval phase is carried over throughout the entire life history of the fish's population. "Orientation during the "critical period" appears to have remarkable demographic consequences," said UM Applied Marine Physics Professor Paris.

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damselfish larvae (Chromis atripectoralis) swimming freely in the open ocean, all in the same direction. Credit: Ricardo Paris -