Age, Growth, and Natural Mortality of Graysby, <i>Cephalophilis cruentata</i>, from the Southeastern United States

Abstract

Graysby (Cephalophilis cruentata) (n = 1308) collected from the southeastern United States Atlantic coast from 2001 to 2016 were aged using sectioned sagittal otoliths. Opaque zones formed February to June (peaking in April). Ages ranged from 2 to 21 years, and the largest fish measured 453 mm TL. Growth morph analysis revealed two regionally distinct growth trajectories: von Bertalanffy growth equations were Lt = 388 (1 − e−0.12(t+5.73)) for fish from North Carolina through southeast Florida (northern region), and Lt = 267 (1 − e−0.17(t+6.20)) for fish from the Florida Keys (southern region). When growth was re-estimated using a fixed t0 value of −0.75 to estimate for smaller fish, growth equations were Lt = 349 (1 − e−0.26(t+0.75)) and Lt = 250 (1 − e−0.43(t+0.75)) for fish from the northern and southern regions, respectively. The age-invariant estimate of natural mortality was M = 0.30 for all fish, while age-specific estimates ranged 0.88−0.28 y−1 for fish aged 1−21 from the northern region and 0.89−0.47 y−1 for fish aged 1−15 from the southern region. This study presents the first comprehensive analysis of life-history parameters for graysby from the Atlantic waters off the southeastern United States, including specimens from both recreational and commercial fisheries.

Keywords

• ageing
• graysby
• growth morphs
• natural mortality