Protocol for histology-anchored macroscopic staging of gonadal maturity in exploited fishes

Here, we present a protocol to assign gonadal maturity stages in commercially exploited fishes using a histology-anchored workflow. We describe steps for recording field metadata, photographing gonads, fixing central gonadal tissue, and processing paraffin sections. We then detail procedures for staining sections with hematoxylin and eosin, diagnosing gametogenic features, and assigning stages using a common reproductive-phase framework with species- and sex-specific reference descriptors. This protocol standardizes documentation and decision logic rather than proposing a new maturity scale.