Embryo and Larval Developmental Staging Guides for Striped Bass

Reliable developmental benchmarks are essential for synchronizing incubation and first-feeding decisions in striped bass (Morone saxatilis) hatcheries, yet existing references are incomplete, outdated, or difficult to apply across variable temperature regimes. We developed contemporary embryo and larval developmental staging guides for striped bass using digital imaging and degree day standardization and paired these guides with measurements of early larval mortality and endogenous energy depletion to provide practical context for hatchery management. Larvae were photographed from hatch through metamorphosis to document key morphological transitions, including yolk absorption, mouth formation, swim bladder inflation, fin differentiation, pigmentation, and diet-related developmental milestones. To place these stages in physiological and survival context, aquarium trials showed there was no clear density-dependent mortality across rearing densities of 1.1–6.8 larvae/mL within the first 72 h post-hatch. Yolk reserves were typically depleted by approximately 4–6 days post-hatch (dph), while lipid droplets persisted longer as secondary endogenous energy stores in unfed larvae through 15 dph. Together, these staging guides provide a transferable developmental framework from fertilization to metamorphosis that links external morphology to endogenous reserve depletion and first feeding, thus supporting standardized hatchery monitoring, improved feeding synchronization, and more consistent assessment of embryo and larval quality.