Common otolith microstructure related to key early life‐history events in flatfishes identified in the larvae and juveniles of cresthead flounder Pseudopleuronectes schrenki

Abstract

Otolith microstructure of reared and wild cresthead flounder Pseudopleuronectes schrenki larvae and juveniles was used to investigate the daily periodicity of ring formation, morphological change and unique otolith structure related to important life events. By comparing microstructural features of P. schrenki with those reported for other flatfish species, it was shown that there may be microstructural features that are common to all flatfishes. In the sagittae and lapillus, a check (a distinct ring) was formed in the centre of otoliths at c. 6 days post hatching, and the daily formation of rings observed outside the check was confirmed. During metamorphosis, accessory primordia (AP) of otolith growth were formed on the outer edge of the sagittae, and the shape of the sagittae became more complex. No AP was formed on the lapilli, however, and otolith rings were concentrically formed throughout the larval and juvenile (≤51·6 mm standard length, L ) stages. It is proposed, therefore, that lapilli are more appropriate than sagittae for analysis throughout the larval and juvenile (≤51·6 mm L ) stages. During metamorphosis, unique rings that are relatively wide and show weak contrast are formed on lapilli (metamorphosing zone, MZ). Hence, the duration of metamorphosis, larval duration and the days of juvenile life can be estimated by the number of rings within the MZ, using rings from the check to outermost ring of the MZ, and that of rings formed outside MZ, respectively. The formation of AP on sagittae as well as the absence of AP, bilateral asymmetry and the formation of a unique structure during metamorphosis on lapilli have also been reported for other flatfishes.

Ontogenetic development of the sagittal otolith of the anchovy, <em>Anchoa tricolor</em>, in a subtropical estuary

“…The species inhabits the estuary at this stage (Araújo et al 2008) and still has more rounded otoliths with a small rostrum, which corresponds to fish with low swimming ability Echeverría 2003, Volpedo et al 2008). The circular shape is inherited from the larval phase (Joh et al 2015), which will be progressively reduced. From 41 to 60-70 mm TL, the swimming capacity of the anchovy increases, enabling its migration out of the estuary.…”

Life in the fast lane: Revisiting the fast growth—High survival paradigm during the early life stages of fishes

“…Fox et al, 2003; Ivarjord et al, 2008) and during the juvenile stage as a result of the formation of secondary primordia (e.g. Joh et al, 2015; Narimatsu et al, 2007). In cases where using otoliths to estimate age is not possible, verifying whether individuals sampled at the endpoint stage were part of the original larval cohort being compared may be difficult, except for species characterized by a punctual spawning season (e.g.…”