Age, growth, and natural mortality of schoolmaster (Lutjanus apodus) from the southeastern United States

Abstract

Ages of schoolmaster (n = 136) from the southeastern Florida coast from 1981–2015 were determined using sectioned sagittal otoliths. Opaque zones were annular, forming March–July (peaking in May–June). Schoolmaster ranged in age from 1–42 years; the largest fish measured 505 mm total length (TL) and was 19 years old. The oldest fish measured 440 mm TL. Estimated body size relationships for schoolmaster were: W = 9.26 × 10−6 TL3.11 (n = 256, r2 = 0.95); W = 2.13 × 10−5 FL2.99 (n = 161, r2 = 0.95); TL = 1.03 FL + 10.36 (n = 143, r2 = 0.99); and FL = 0.96 TL − 8.41 (n = 143, r2 = 0.99), where W = whole weight in g, FL = fork length in mm, and TL in mm. The fitted von Bertalanffy growth equation was: Lt = 482 (1 − e−0.12(t+2.79)) (n = 136). Based on published life history relationships, a point estimate of natural mortality for schoolmaster was M = 0.10, while age-specific estimates of M ranged from 1.57–0.18 for ages 1–42.

Age, Growth and Natural Mortality of Blackfin Snapper Lutjanus buccanella from the Southeastern United States and U. S. Caribbean

“…The observed maximum age of Gray Snapper, a close congener, is 25 years (Burton 2001 (Brennan 2004;ML Burton, unpublished data). Schoolmaster (Lutjanus apodus), a small to medium snapper found in coastal habitats in the Florida Keys, was found to have a maximum age of 42 years (Potts et al 2016). The maximum age of Blackfin Snapper from this study should be not be considered a true maximum age since, with increased sampling, a new maximum could be encountered.…”

“…Cubera Snapper, the largest lutjanid in the SEUS, is both larger and longer-lived than Blackfin Snapper (maximum size 1422 mm TL, maximum age 55 years; ML Burton, unpublished data), but the range of estimated values for M was similar, 0.50-0.05 for ages 1-55. Survivorship to the oldest age is similar between these three lutjanids, with Schoolmaster survivorship estimated at 0.3% (Potts et al 2016) and Cubera Snapper survivorship estimated at 0.2% (ML Burton, unpublished data).…”

“…When we compare estimates of M from this study with estimates from other lutjanids, we need to be cognizant of differences in both maximum size and longevity, two factors that influence estimates of M. Potts et al (2016) estimated M = 0.47-0.12 for Schoolmaster for ages 1-42. Schoolmaster is a slightly smaller-sized fish than Blackfin Snapper but it has a higher maximum age (42 years vs. 27 years).…”

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

“…Age determination was based on recording an opaque zone count and edge type code by an experienced reader (MLB) with extensive experience interpreting otolith sections ( Burton, 2001 ; Potts, Burton & Myers, 2016 ) with no knowledge of date of capture or fish size for each sample. The edge codes refer to the type of zone, opaque or translucent, and in the case of translucent zones the amount of that zone between the last opaque zone formed and the otolith section edge.…”

Age, growth and reproductive biology of a widespread coral reef fish, yellowfin goatfish Mulloidichthys vanicolensis (Valenciennes, 1831)

“…The APE (5.3) and c.v. (6.6) shown in this study were slightly higher than those of the Brazilian goatfish Pseudupeneus maculatus (Santana et al ., 2006; APE: 2.3, c.v. : 4.7) and the Okinawan Mulloidichthys flavolineatus (Samejima et al ., 2021; APE: 3.3, c.v. : 4.4) but still within the acceptable levels of APE and c.v. , proposed by Campana (2001), of 5.5 and 7.6%, respectively. Furthermore, they were comparable to other well‐studied commercial fishes such as Lutjanidae, Scaridae and Serranidae (Barnett et al ., 2020; Burton et al ., 2016; Gordo et al ., 2016; Potts et al ., 2016). Thus, the precision of age determination in this study is considered acceptable.…”