Age, growth, mortality and reproductive seasonality of jolthead porgy, Calamus bajonado, from Florida waters PeerJ

Ages of jolthead porgy (Calamus bajonado Schneider 1801) (n = 635) from Florida commercial and recreational fisheries from 2008–2016 were determined using sectioned sagittal otoliths. We determined, using edge-type analysis, that opaque zones were annular, forming March–June (peaking in April). Jolthead porgy ranged from 1–13 years, and the largest fish measured 680 mm TL (total length, mm). Body size relationships for jolthead porgy were TL = 1.09FL + 20.44 (n = 622, r2 = 0.99), FL = 0.90 TL –14.26 (n = 622, r2 = 0.99), and W = 1.1 × 10−5 TL3.06 (n = 577), where W is total weight (grams, g) and FL is fork length (mm). The von Bertalanffy growth equation for jolthead porgy was Lt = 737(1 − e−0.14(t+2.02)) (n = 635). Point estimate of natural mortality was M = 0.32, while age-specific estimates of M ranged from 0.58–0.17 y−1 for ages 1–13. Catch curve analysis estimated the instantaneous rate of total mortality Z = 0.70, while instantaneous rate of fishing mortality F was 0.38. Macroscopic staging of female gonads indicated the presence of hydrated oocytes from December–March, and GSI data indicates that peak spawning in females occurs during March. This study presents the first published findings of life history parameters for jolthead porgy from the Atlantic waters off the southeastern United States.