Reproductive behaviour of a temperate serranid fish, Paralabrax clathratus(Girard), from Santa Catalina Island, California, U.S.A.

The reproductive behaviour of the kelp bass Paralabrax clathratus was studied on Santa Catalina Island, California, U.S.A. from April 2000 to September 2002. Adults formed aggregations of three to > 200 individuals, and spawning occurred within subgroups of three to 23 individuals that contained a single female. The gonado‐somatic index ( I _G) of collected ripe males (mean = 5·8%, range = 0·5–13·1%) indicated a large investment in sperm production that is common in group‐spawning fishes characterized by intense sperm competition. Spawning occurred 32 min before sunset to 120 min after sunset, and both males and females were capable of spawning multiple times during a single evening. Behavioural observations of adults and estimates of spawning periodicity from the collection of females with hydrated oocytes suggested that spawning occurred continuously throughout the summer months and showed no significant relationship with the lunar cycle. In general, the spawning behaviour of kelp bass was similar to other functionally gonochoric, group‐spawning serranids. The dynamics of P. clathratus spawning aggregations, however, were inconsistent with that of tropical reef fish spawning aggregations, including the transient spawning aggregations of some tropical serranids. Aggregation spawning appeared to be an important component of the annual reproduction of this species.     

Ovulation does not constrain egg parcel size in the simultaneous hermaphrodite Serranus subligarius

Among egg trading hermaphrodites, any factor which limits the number of eggs released by a female role hermaphrodite can potentially limit the mating success of the male role hermaphrodite fertilizing those eggs. This work examines the hypothesis that the timing of ovulation constrains the size of egg parcels and thereby limits male mating success in the egg parceling hermaphroditic fish Serranus subligarius. Two alternatives were evaluated: (1) Ovulation is a discrete event preceding spawning. It does not constrain the size of egg parcels and therefore does not limit mating success of male role partners. (2) Ovulation is an incremental process occurring throughout the spawning period. It limits the number of eggs available for release in each parcel and thereby limits mating success of the male role partner. Assessment of ovulation was conducted in a field stock of S. subligarius. Fish from size matched pairs were manually stripped at the onset of the spawning period or quarantined and sampled at the end of the spawning period. Fish sampled at either time point had the same number of eggs, suggesting that ovulation was a discrete event occurring at the onset of the spawning period. The diurnal cycle of ovulation was observed in naturally spawning hermaphrodites captured at intervals throughout the day. Ovulation began 2–4 h before spawning began. Some fish appeared to ovulate the entire day's clutch of eggs before spawning, while other fish released egg parcels before completing ovulation. I conclude that the pattern of ovulation is not uniform throughout the spawning stock. Because of the variability in timing of ovulation relative to parcel release, ovulation does not consistently limit the size of egg parcels and therefore is unlikely to be a physiological limit to male role mating success in S. subligarius hermaphrodites.     

Characterization of polymorphic microsatellite loci from black grouper,Mycteroperca bonaci (Teleostei: Serranidae)

Many groupers in the western Atlantic are vulnerable to overfishing, and appropriate management requires knowledge of the population structure of these fish. To this end microsatellite markers were developed from black grouper, Mycteroperca bonaci, using an enrichment procedure. Five loci with levels of polymorphism ranging from 0.5 to 0.9 were selected. These markers also proved to be useful in scamp, M. phenax; red grouper, Epinephelus morio; and goliath grouper, E. itajara. Conformation to Hardy–Weinberg equilibrium was observed except for heterozygote deficiencies noted for E. morio at two of the loci used for this species.     

Variation in reproductive success and gonadal allocation in the simultaneous hermaphrodite,Serranus fasciatus

Summary This paper examines the correlates of individual size, reproductive success, gonadal allocation, and growth in a hermaphroditic reef fish. Individuals in S. fasciatus mature as simultaneous hermaphrodites; large individuals subsequently lose female function and become functional males. Daily female reproductive success was highly correlated with both hermaphrodite size and amount of female gonadal tissue. Three separate comparisons gave a positive correlation between male reproductive success and male gonadal allocation: (1) Males had higher levels of male gonadal allocation and male reproductive success than hermaphrodites. (2) The percent of gonad allocated to male tissue in hermaphrodites was higher in the year they had higher male mating success. (3) Male gonadal tissue of hermaphrodites was positively correlated with male reproductive success in the year that male reproductive success by hermaphrodites was higher and more variable. There was no evidence for a trade-off between male function, female function, and growth among hermaphrodites. Many of these patterns have also been observed in plants, but the selective pressures leading to these patterns in S. fasciatus and plants are probably quite different.     

INTRASPECIFIC VARIATION IN SEX ALLOCATION IN A SIMULTANEOUS HERMAPHRODITE: THE EFFECT OF INDIVIDUAL SIZE

Within a population of simultaneous hermaphrodites, individuals may vary in both their current reproductive investment (biomass invested in gonads) and in how they allocate that investment between male and female function. In the chalk bass, Serranus tortugarum, estimates of both reproductive allocation and reproductive success as a male and a female can be made for individuals of different sizes. As individuals increase in size, their investment in gamete production increases, and there is a shift in allocation to a stronger female bias. Spawning frequency as a female in pair spawnings and as a male in both pair spawning and streaking (an alternative mating tactic) does not vary with individual size. As a result, larger individuals should release more sperm or eggs per spawn. Size-assortative pair spawning in this species leads to larger individuals having higher potential returns in total male reproductive success than smaller individuals, which should lead to increases in absolute levels of sperm production in larger individuals when individuals compete for fertilizations through sperm competition. However, smaller individuals contribute a smaller proportion of the sperm released in spawns with multiple spawners and thus are under more intense sperm competition than larger individuals, which should select for increases in male allocation in smaller individuals, all else equal. A local-mate-competition (LMC) model predicts that these factors select for increasing absolute male and female investment with individual size but a relative shift to more female-biased allocation as individual size increases. These predictions are supported by gonadal data. The predictions of average male allocation from the quantitative LMC model were 21.6% and 25.7%, whereas the collections averaged 21.3%. This close agreement of both the mean male allocation and its relative shift with individual size between model and data support the hypothesis that size-specific shifts in sex allocation in this species represent an adaptive response to patterns of mating success and sperm competition.     

Sexual development and sexuality in the Nassau grouper

Hermaphroditic sexual patterns are widespread among teleosts and are especially characteristic of certain perciform families. Among the most diverse groups of hermaphroditic species are the groupers, hamlets and sea basses of the family Serranidae. Like other groupers, the epinepheline serranid, Epinephelus striatus , the Nassau grouper, has long been assumed to exhibit monandric protogyny (a form of hermaphroditism in which all males derive from adult females by sex change). Histological and demographic data, however, indicate that the sexual pattern of this species is not monandric, and that, unlike other group species, the juveniles pass through a bisexual stage of gonadal development. Sexuality in the Nassau grouper is essentially gonochoristic, with potential for sex change. The combination of bisexuality and gonochorism is previously undescribed in the serranids.     

First record of Cephalopholis taeniops (Valenciennes) in the Mediterranean Sea

Two specimens of African hind Cephalopholis taeniops (Valenciennes, 1828) are recorded for the first time in the Mediterranean Sea, in the coastal area of Gulf of Syrte, Libya. This finding represents an additional case of a tropical species of fish of West African origin in the Mediterranean Sea.     

Liopropoma dorsoluteum sp. nov., a new serranid fish from Okinawa, Japan

A new serranid fish,Liopropoma dorsoluteum sp. nov., is described on the basis of two specimens from Yaeyama Is., Okinawa, Japan. The new species is most similar toL. erythaeum Randall & Taylor, 1988, in having the following characters: Dorsal fin rays VIII, 12; anal fin rays III, 9; pored lateral line scales 52–53; anterior nostril situated midway between posterior nostril and anterior tip of snout; slightly forked caudal fin with both lobes rounded. It differs from the latter species in having a shorter pectoral fin (23.4–23.8% SL vs. 26.9–29.0% SL), greater preanus length (65.6–68.0% SL vs. 63.3–65.1% SL), fewer gill rakers (6+12 vs. 6–7+14–15) and yellow coloration on the back (vs. light red on head and body) in fresh specimens.     

Biochemical systematics of some serranids from Taiwan (Pisces, Serranidae)

An electrophoretic study of genetic variation at 17 loci in ten serranids belonging to three subfamilies (Anthiinae, Epinephelinae and Serraninae) was carried out to assess their systematic relationships. A relationship dendrogram was constructed from the fenetic identities calculated b Nei's method for all pairwise cornarisons. These fishes were divided into three major welldefined groups: Anthiinae, Epinepielinae and Serraninae. Although the relationships among them appear slightly different from that deduced from morphological features; e. g., Serraninae are distant from Anthiinae and Epinephelinae biochemically, but are closer to Antiinae than to Epinephelinae morphologically. However, a tendency for an increase of the genetic distance in higher categories is obvious (Table 5).     

A preliminary market-based analysis of the Pohnpei,Micronesia, grouper (Serranidae: Epinephelinae) fishery reveals unsustainable fishing practices

Serranids are important components of artisanal and commercial catch worldwide, but are highly susceptible to overfishing. In Pohnpei (Micronesia), a recent coral reef fish market survey revealed a reliance on night-time spearfishing and a serranid catch composed primarily of juveniles and small adults of practically all epinepheline species. Fishing effort was concentrated in one of five municipalities and was disproportionate to the population distribution. Lagoon areas were fished preferentially to outer reef areas, with both catch size distribution and species composition similar between the two areas. Some species were unique to a particular gear type, but catch composition did not vary substantially between spear and line fishing. Existing seasonal sales bans, meant to protect reproductively active serranids, appeared to place additional pressure on other families during ban periods. The study identified the need for a comprehensive management plan that merges traditional measures, including size limits and gear restrictions, with precautionary management tools. Specifically, the scale and scope of marine protected areas should be increased to protect juveniles and other life history stages over wider areas than currently employed.