Scientia Marina, Vol 63, No S1 (1999)

Age validation and growth of yolked larvae of Patagonotothen tessellata (Richardson, 1845) (Pisces: Nototheniidae) from the rocky littoral of the Beagle Channel, Argentina


https://doi.org/10.3989/scimar.1999.63s1469

Gustavo Alfredo Rae
Centro Austral de Investigaciones Científicas CADIC-CONICET, Argentina

Nemesio Amaro San Roman
Centro Austral de Investigaciones Científicas CADIC-CONICET, Argentina

D. Emilse Spinoglio
Centro Austral de Investigaciones Científicas CADIC-CONICET, Argentina

Abstract


Age and growth estimation of Patagonotothen tessellata larvae over the endogenous period was estimated by examining their otolith microstructure and the associated increment deposition rate. Analyzed specimens were incubated from egg-masses collected in Lapataia Bay, Beagle Channel, Argentina. Validation was performed by monitoring reared larvae of known ages. Actual age and increment count were regressed suggesting a daily deposition of one ring in the otolith, which began at hatching time and continued until larvae reached sixteen days old (time of massive mortality). Mean lengths at each age were estimated using Richards´ growth function; their constant (m) attained a value close to zero indicating that the data fitted to the von Bertalanffy model. Absolute growth rate was 0.55 mm*d-1of total length at hatching, dropped near zero on the fifth day after hatching and afterwards, there was no growth. Yolk absorption rate (expressed as a ratio between minor axis/major axis of the vitelline-sac) showed a similar variation as that observed in absolute growth rate during the endogenous period. The total yolk absorption took five days in the unfed larvae group and seven days in the fed larvae group. The rapid absorption of the yolk and the observed growth pattern suggest that Patagonotothen tessellata larvae have a short endogenous period, reaching the state of first food uptake five days after hatching.

Keywords


Fish larvae; otolith; age determination; daily growth; Notothenioidea; Patagonotothen tessellata

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