SEM photographs showing daily growth increments (DGIs) and growth checks in an Anguilla marmorata otolith. (a) SEM photographs showing daily growth increments (DGIs) and growth checks in an otolith of an Anguilla marmorata elver and measurements of otolith radii (R) and counts of DGIs (T) according to the developmental stage. Scale bar = 20 μm. (b to e) Magnified portions of (a) showing (b) estuarine check (EC) and the otolith edge (e), (c) metamorphosis check (MC), (d) discontinuous (dark band, Dz) and increment (light band, Lz) zones, and (e) the primordium (P), hatching check (HC), and first feeding check (FFC). R
t, radii from the primordium to the FFC, MC, and OE, respectively; R
t−m, distance from the MC to the OE; OL, otolith length; T
t−m, counts of DGIs on radii of R
m and R
t and the section R
t−m between the MC and OE, respectively.