Growth and secondary production of an eventual reef fish during mangrove residency

Abstract

Hierarchical data frameworks have been proposed to determine the relative value of fish habitats. Although conceptually accurate, judgments as to which habitat is more “essential” are limited by a lack of available information. This work provides much needed growth and production rates for gray snapper ( Lutjanus griseus), an ontogenetic habitat shifting reef fish, during mangrove residency. Ages were estimated using modal progression analysis of length–frequency distributions coupled with a biologically-realistic spawning date. Growth estimates place age-1 L. griseus at 155 mm (TL), age-2 at 243, and age-3 at 302 mm. These size-at-age estimates are consistent with otolith-based studies and are a natural extension of linear growth models for early juveniles. Lutjanus griseus primarily use southeastern Florida mangrove shoreline habitats for approximately 2 years between 0.86 and 2.84 years of age. Corresponding production:biomass ratios for these cohorts were 1.51 and 0.90. While these values are similar to other estimates for fishes inhabiting vegetated coastal wetlands in North America, they are much less than new estimates from a Bahamian mangrove creek system. These new data highlight important differences between the habitat value of mangrove shorelines of continental (low-relief) and island (high-relief) systems.