The Spawning, Embryonic and Early Larval Development of the Green

Animal Reproduction Science 125 (2011) 196–203 Contents lists available at ScienceDirect Animal Reproduction Science journal homepage: www.elsevier.com/locate/anireprosci The spawning, embryonic and early larval development of the green wrasse Labrus viridis (Linnaeus, 1758) (Labridae) in controlled conditions a,∗ a b a a V. Kozulˇ ,N.Glavic´ ,P. Tutman , J. Bolotin , V. Onofri a Institute for Marine and Coastal Research, P.O. Box 83, 20000 Dubrovnik, Croatia b Institute of Oceanography and Fisheries, 21000 Split, Croatia a r t i c l e i n f o a b s t r a c t Article history: Green wrasse, Labrus viridis (Linnaeus, 1758), is an endangered species in the southern Adri- Received 21 May 2010 atic Sea, but it is also of interest for potential rearing in polyculture with other commercial Received in revised form 17 January 2011 species for the repopulation of areas where it is endangered or as a new aquaculture species. Accepted 24 January 2011 A parental stock of the green wrasse was kept in aquaria for six years. The spawning, embry- Available online 2 February 2011 onic and early larval development maintained under controlled laboratory conditions are described and illustrated. The average diameter of newly spawned eggs was 1.01 ± 0.03 mm. Keywords: Mature and fertilized eggs were attached to the tank bottom by mucus. Hatching started Green wrasse ◦ after 127 h at a mean temperature of 14.4 ± 0.8 C. The average total length of newly hatched Labrus viridis ± Spawning larvae was 4.80 0.22 mm. Absorption of the yolk-sac was completed after the 5th day Eggs when larvae reached 5.87 ± 0.28 mm. Larvae Larvae were fed with the rotifers Brachionus plicatilis. The pigmentation of L. viridis larvae Adriatic Sea is similar to that of Labrus merula and Labrus bergylta, but the main differences between these species are in the size of larvae and the development time of the melanophores on the anal fin-fold (five days later than with L. merula) and on top of the head (nine days earlier than with L. merula). © 2011 Elsevier B.V. All rights reserved. 1. Introduction could still only be caught in the southern Adriatic. The same data (Onofri, 1975) concerning the endangerment of Green wrasse, Labrus viridis (Linnaeus, 1758), is an wrasse was noted ten years later, while researching various endangered species in the southern Adriatic Sea, but it is species of labrids along the eastern shores of the Adriatic. also of interest for potential rearing in polyculture with It is the only species in Croatian coastal waters whose fish- other commercial species for the repopulation of areas ing and trading is permanently banned due to population where it is endangered or as a new aquaculture species. reductions since 2002 (Directive on the Protection of Fish Green wrasse is distributed throughout the Mediterranean, and Other Marine Organisms, National Gazette, 101/02, in the western region of the Black Sea and in the east- 2002). In the time prior to the ban, wrasse was caught at ern Atlantic from Portugal to Morocco (Quignard and Pras, a rate of about 2 tons of per year along the eastern shores 1986). Quingnard (1966) noted more than 40 years ago that of the Adriatic (Jardas, 1996). There are no available data the wrasse was a very rare species in the northern Adriatic, on the annual catch of wrasse since the introduction of the scarcer in the central Adriatic and that larger specimens Directive and up to the present time. During the 1970s, the largest recorded length of green wrasse was 60 cm (Onofri, 1975), while it decreased to 55 cm in the nineties (Jardas, ∗ 1996). The average catch length 10 years ago was 20–35 cm, Corresponding author. Tel.: +385 20 323131; fax: +385 20 323872. E-mail address: [email protected] (V. Kozul).ˇ with a weight of up to 1.7 kg (Jardas, 1996). In the south- 0378-4320/$ – see front matter © 2011 Elsevier B.V. All rights reserved. doi:10.1016/j.anireprosci.2011.01.013 V. Kozulˇ et al. / Animal Reproduction Science 125 (2011) 196–203 197 ern Adriatic, the wrasse inhabits rocky seabeds with many small pelagic fish, mollusks and sea urchins. When male crevices, and it is always one individual. These habitats are interest for females increased, fish were removed to the located on the outer side of islands facing the open sea laboratory tank (300 l). These specimens, one male (420 g, and along vertical rocky sea beds (Onofri, 1975) at depths TL 34.0 cm, 4+ age) and one female (480 g, TL 33.0 cm, 4+ of 2–50 m (Jardas, 1996). The reasons for the reduction of age) spawned spontaneously. During the spawning period, ◦ green wrasse populations are due to intense commercial temperature was 14.2 C, salinity 38.1 psu, oxygen 7.2 mg/l, and sport fishing. and pH 7.9. After spawning, the fish were returned to the The green wrasse is an obligatory carnivore, preying on aquarium pool. The same male also spawned with another mollusks, worms, crabs and urchins (Quignard and Pras, female (458 g, TL 31.0 cm, 4+ age) ten days after the first 1986; Onofri, 1975; Jardas, 1996). The species is a protog- spawning. ynous hermaphrodite, and sex commences at a length of 27 cm (Quignard and Pras, 1986; Jardas, 1996). Spawning 2.2. Egg incubation and embryonic development takes place at the end of winter and at the beginning of spring in natural conditions (Onofri, 1975; Jardas, 1996). The first release of eggs occurred in the aquarium Onofri (1975) states that this species attaches eggs to algae, tank, and immediately afterwards, the male and the but the author did not give any data on this phase of female were transferred to the laboratory tank, where the development for eggs transported to the laboratory. Onofri spawning continued. We gathered the first eggs released (1970, 1975) presented the morphological and meristic from the aquarium’s gravelly bottom, together with the data of adult stages of green wrasse and other species of gravel to which they were attached, which served as a labrids in the southeastern Adriatic, but there is insufficient control for embryonic development in further research. information on the early developmental stages of green Prior to stocking in the experimental tank for incubation, wrasse. Information on the spawning and early develop- these egg samples were disinfected for 15 min using a mental stages of another LABRID species Labrus merula on low-concentration solution of formaldehyde (1 part 37% the eastern shores of the Adriatic is given by Dulciˇ c´ et al. formalin to 600 parts of water) (Ferguson, 1978; Cross and (1999). Globally, much research has been carried out due Needham, 1978). This egg sample was placed inside the lab- to problems with parasites, such as sea lice. Due to dam- 2 oratory tank in a dish the size of the bottom 80 cm , with ages in the rearing of salmonid caused by sea lice, in the a permeable bottom made of plankton netting of 500 ␮m last few years, the possibility of biological control by using mesh for better aeration. Other eggs that were released cleaner wrasse has become very interesting for aquacul- during spawning in the laboratory tank were attached to ture (Bjordal, 1990; Darwall et al., 1992; Kvenseth, 1993; the tank bottom and could not be retrieved for sampling. Treasurer, 1993, 1994, 1996, 2002; Deady et al., 1995; The eggs had a constant daily exchange of 50–70% seawater Young, 1996; Tully et al., 1996). through a 50-␮m mesh net. The experiment was carried out Due to the vulnerability and declining population num- under an artificial photoperiod (12L:12D h, 2000 lux). The bers of this species on the east coast of the southern water was gently aerated from the bottom of the tank. Adriatic, our investigations of controlled breeding are ◦ Eggs and larvae were incubated from 13.8 to 15.5 C useful for repopulation or as potential mariculture in poly- ◦ (mean 14.4 C). Dead larvae were removed daily. After fer- culture production for the fish market. This paper presents tilization, a sample of 10–15 eggs was taken every 5–7 min the first data on egg, embryonic and larval development of to determine the exact time of first cleavage. Random sam- wrasse under controlled laboratory conditions. The objec- ples of 10–15 eggs were taken every hour during the first tives are to describe the early life history and to assist in 10 h after fertilization, and subsequently every 6 h. The egg the identification of the planktonic stages of this species, diameter was measured and the stages of the embryonic and also to provide first information on possible breeding. development were recorded using a binocular microscope. Photos of individual stages were taken. The number of 2. Materials and methods eggs and larvae were significantly lower during the sec- ond spawning with the same male and the other female. 2.1. Brood stock Due to the low number of spawned eggs during the sec- ond spawning, egg measurements and the monitoring of Parental fishes were collected from southeastern Adri- embryonal development in this group was not carried out. atic waters, around the island of Lokrum near Dubrovnik. Fish were caught on hooks or in fish traps and, after being quarantined, they were placed with other specimens in 2.3. Larval development the brood stock tank. A parental stock (two males and six females) was kept in aquaria at the Institute for Marine After hatching commenced, various measurements and Coastal Research in Dubrovnik.

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