Development of Labrus Bergylta (Ascanius 1767) Larvae from Hatching to Metamorphosis

Abstract

Ballan wrasse, Labrus bergylta (Ascanius, 1767), has commercial interest as a cleaner fish in aquaculture, and culture of juveniles may be a good alternative to catching wild fish. However, basic knowledge of early development is limited. To study hatching and larvae ontogenesis, eggs were collected from a broodstock of wild caught ballan wrasse held in captivity. Larvae were fed rotifers for 27 days; Artemia was introduced at day 20 and fed larvae to day 49 after hatching. Age at hatching, and larval ontogenesis based on external morphological features were linked to the chronological age of larvae as days post hatching (DPH) and physiological age as degree day (°C.day) and standard length (SL). The ballan wrasse egg diameter was 1.05 ± 0.04 mm and 0.87 ± 0.05 mm with and without the gelatinous layer, respectively, and hatched at a SL of 3.64 ± 0.05 mm, 7 days, i.e., 72°C.day, after fertilization. The ontogeny of larvae from hatching to metamorphosis was divided into four stages. Yolk sac larva, 0 to 9 DPH (SL 4.28 ± 0.11 mm), where mouth opens and pigmentation of the eyes is seen. Dilated swim bladder is visible. Preflexion larva, 10 to 25 DPH (SL 5.35 ± 0.30 mm); yolk sac has disappeared, and initial formation of caudal fin rays occurs. Gaseous inflation of swim bladder is observed. Flexion larva, 26 to 33 DPH (SL 5.9 ± 0.78 mm), initial resorption of primordial fin fold is seen. Postflexion larva, 34 to 49 DPH (SL 10.52 ± 0.82 mm) by the end of this stage (age 686°C.day), the dorsal, anal, caudal and pelvic fins were developed. The ontogenetic development, linked to SL, chronological and physiological age, provides a baseline reference and makes it possible to compare developmental levels in future studies of ballan wrasse in culture and wild populations.

Effect of cultivated copepods (Acartia tonsa) in first-feeding of Atlantic cod (Gadus morhua) and ballan wrasse (Labrus bergylta) larvae

“…Even only 1 week with copepod feeding resulted in significantly larger juveniles than for the larvae fed rotifers, which was demonstrated for both species at the end of the experiment on 60-61 dph. The growth of cod and the growth of ballan wrasse larvae fed rotifers were in the same range as observed in other experiments (Baskerville-Bridges & Kling 2000;Fletcher et al 2007;Wold et al 2007;Garcia et al 2008;Ottesen et al 2012;Hansen et al 2013). Although there were no differences in larval growth between the two groups fed rotifers for any of the species, significant differences were found between them in survival and stress tolerance.…”

Historical gene flow constraints in a northeastern Atlantic fish: phylogeography of the ballan wrasseLabrus bergyltaacross its distribution range

“…In fact, population structure has also been recorded for a variety of fishes [14,62]. This also seems to be the case of the ballan wrasse, which has a relatively long PLD of 37–49 days [67] but revealed genetic structure along the sampled area, especially when considering the CR dataset. The locations from Norway, Azores and the rest of European sites were considered to be significantly different.…”

Growth and stress factors in ballan wrasse (Labrus bergylta) larval development

“…However, drugs have remained the sea louse treatment of choice. Recently, reduced sea louse susceptibility to the available veterinary compounds has boosted the capture and deployment of wild wrasse, raising concern over overexploitation and depletion of wild stocks (Ottesen, Dunaevskaya & D'Arcy 2012).…”