Momma's larvae: Maternal oceanographic experience and larval size influence early survival of rockfishes

Identifying factors that affect larval mortality is critical for
understanding the drivers of fish population dynamics. Although larval
fish mortality is high, small changes in mortality rates can lead to large
changes in recruitment. Recent studies suggest maternal provisioning can
dramatically affect the susceptibility of larvae to starvation and
predation, the major sources of early-life mortality. We measured otolith
core width-at-extrusion and validated that this is a proxy for larval
size-at-extrusion for eight species of rockfishes
(genus Sebastes) to examine the influence of initial larval size
on larval growth and survival and to understand how oceanographic
conditions experienced by gestating females affect larval size (i.e.,
quality). Otolith core width-at-extrusion was significantly positively
related to larval rockfish recent growth rate (5/7 species with sufficient
sample size) and survival (all eight species). This suggests that
individuals that are larger at extrusion generally grow faster and are
more likely to survive early life stages. Otolith core width-at-extrusion
was positively related to higher presence of Pacific Subarctic Upper Water
and was negatively related to warmer, saline waters at the depths
gestating mothers inhabited during the months prior to larval collection.
In addition, otolith core width was larger further from fishing ports,
possibly because these locations were historically less fished, contained
more older, larger females, and/or had inherently better habitat quality
(higher Pacific Subarctic Upper Water) than sites closer to shore. These
results indicate that the environmental conditions female rockfish
experience during gestation drive the size of the larvae they produce and
impact larval growth and survival.