Spawning behaviour ofCheimerius nufar in captivity

Abstract

SynopsisThe santer Cheimerius nufar is widespread in tropical and subtropical waters of the western Indian Ocean and forms an important component of linefish catches along the east coast of southern Africa. Observations of spawning behaviour in captivity have revealed that spawning occurs during spring over a period of four months. Mating takes place at sunrise and may continue for up to 105 min (mean duration = 60 min). During spawning males become dark with prominent white markings. They become very aggressive and set up territories. Females remain a uniform silvery-pink. Mating occurs between males and females of similar sizes, culminating in egg and sperm release near the surface. Individual fish spawned up to 14 times during a morning. 'Streaking' occurred throughout the season, with a second male joining a spawning pair and releasing gametes simultaneously. Slinger, Chrysoblephus puniceus, a dominant fish on offshore reefs in the same region, interfered with spawning throughout the season and were observed to eat eggs when they were released. The spawning strategy of C. nufar is similar to protogynous species in several respects, indicating that this functional gonochorist may not conform to current theoretical predictions.

Mating behaviour and gamete release in gilthead seabream (Sparus aurata, Linnaeus 1758) held in captivity

“…These indications that presented opportunities consisted of: a) spawning was often in a pair indicating the pair could select each other, b) aggregations brought all the fish together for close contact to aid selection and spawning was often soon after an aggregation, c) males followed females perhaps seeking selection, d) males nudged females to possibly stimulate selection, e) females were observed to swim away from advances from males and f) males changed colour changing appearance to perhaps aid selection by the female. Aggregations and/or courtship behaviours similar to the present study have been described in other species of Sparidae including silver seabream (Chrysophrys auratus) (Smith, 1986;Mylonas et al, 2011), santer seabream (Cheimerius nufar) (Buxton & Garratt, 1990;Garratt, 1991), roman seabream (Chrysoblephus laticeps) (Buxton, 1990), silver bream (Rhabdosargus sarba) (Leu, 1994) and southern black bream (Acanthopagrus butcheri) (Mylonas et al, 2011) and nonSparidae such as the spotted sand bass (Paralabrax maculatofasciatus) (Miller & Allen, 2006), yellowtail amberjack (Seriola lalandi) (Moran et al, 2007), dusky grouper (Epinephelus marginatus) (Zabala et al, 1997), cubera snapper (Lutjanus cyanopterus) (Heyman et al, 2005) and white seabass (Atractoscion nobilis) (Aalbers & Drawbridge, 2008). However, in the present study, aggregations were not always observed immediately prior to gilthead seabream spawning and no inter-individual dominances were observed.…”

“…The reproductive behaviour was similar to that described for other Sparidae species (Smith, 1986;Buxton, 1990;Buxton & Garratt, 1990;Garratt, 1991;Leu, 1994;Mylonas et al, 2011). Gilthead seabream were observed to form defined aggregations prior to the spawning event and females were observed to make a spawning rush with one or more males that finished with gamete liberation.…”

“…Cameras were installed in each tank 5 cm under the water surface and adjusted to rius nufar) (Buxton & Garratt, 1990;Garratt, 1991), roman seabream (Chrysoblephus laticeps) (Buxton, 1990), silver bream (Rhabdosargus sarba) (Leu, 1994) and southern black bream (Acanthopagrus butcheri) (Mylonas et al, 2011). Although there was variation among species a general similarity was observed (see review in Mylonas et al, 2011).…”

“…Spawning was usually early morning (dawn) or early evening (dusk) (06:00 and 19:00, respectively). Courtship consisted of males pursuing and nudging females, a tight circling swimming behaviour to form aggregations before spawning, which consisted of a spawning rush usually either to perform pair spawning involving a single pair (a male and a female) or group spawning a single female followed by multiple males (Smith, 1986;Buxton & Garratt, 1990;Garratt, 1991;Leu, 1994;Mylonas et al, 2011).…”

“…The following types of behaviours and observations were described from the videos: i) pre-spawning interactions between individuals or in a group, ii) the behaviour directly associated with gamete liberation, iii) fish aggregation patterns and duration, iv) number of fish participating in each spawn (pair or group spawning) and the sex proportion per spawn, v) the frequency, duration and position of fish in tank when spawning and vi) estimation of the average distance (estimated from known distances between reference points in the tank) of the spawning rush. These parameters were selected in accordance to previous work realized on Sparidae species (Smith, 1986;Buxton & Garratt, 1990;Garratt, 1991;Leu, 1994;Mylonas et al, 2011) and in particular terminology defined by Domeier & Colin (1997) was used to describe behaviours and actions. These included the following definitions of types of spawning from Domeier & Colin (1997) …”