Aspects of reproductive biology of Labeo horie Heckel (Pisces: Cyprinidae) in Lake Chamo, Ethiopia

Labeo horie Heckel is increasingly becoming commercially important in Lake Chamo but its reproductive biology in the lake is not well enough to guide its management. Sex ratio, breeding season, length at first maturity and fecundity of L. horie were studied from 1197 fish samples collected between August 1998 and October 1999 in Lake Chamo, Ethiopia. The sex ratio was significantly different (χ ² = 12.12, P < 0.001). The peak‐breeding period was during the rainy months of March to May, during which time more than 90% of both sexes had ripe gonads. The size at maturity ( L _m50 ) of males was 52 cm while the L _m50 of females was 62 cm. The smallest ripe male in the catch was 46.7 cm and weighed 890 g while the smallest ripe female caught was 49.5 cm and weighed 1145 g. The weight of ripe ovaries ranged from 54.3 g to 991.8 g and contained between 68,400 and 1,320,400 eggs. Relative fecundity ranged between 60 and 290 eggs per g of body weight. The relationships between fecundity and total length and between fecundity and total weight were curvilinear, while the relationship between fecundity and ovary weight was linear. L. horie conformed to the general pattern of reproduction in a tropical environment where peak‐breeding activity occurred during the rainy season. In order to protect the spawning population, fishing pressure should be minimized during breeding time at the shallower littoral regions.     

Spawning frequency, fecundity, egg weight and spawning type of silver pomfret, Pampus argenteus (Euphrasen) (Stromateidae), in Kuwait waters

Silver pomfret, Pampus argenteus, were collected by fishing with drift gillnets on one spawning ground in Kuwait waters during 1998–2000. Fish size frequency, sex ratio, maturation cycle, spawning frequency, fecundity and egg weight were assessed. The length–weight relationship differed between sexes whereby females were significantly bigger than males. Spawning started in mid‐May and continued until early October. During this time the water temperature ranged from 26.0 to 32.8°C, salinity was ? 39.0‰ and water depth ranged between 5 and 12 m. Large females spawned earlier than young spawners and the overall percentage of males during the spawning period was 70.3%. Spawning occurred after 13.00 h, with peak spawning between 15.00 and 18.00 hours during outgoing tide. Mean daily spawning frequency amounted to 63.2%. Spawning activity was found to be associated with the lunar cycle and spawnings were concentrated during the first and third quarters of the moon period, indicating a semilunar reproduction cycle. It was concluded that a female would spawn at least six times during the season. No change was observed in relative fecundity during the peak spawning season (June–August). Average relative batch fecundity was 176.3 eggs g^?1 somatic weight (SW), corresponding to a relative total fecundity of 1058 eggs g^?1 SW, which is 1.5 times higher than estimates obtained from counting the standing stock of oocytes. Bigger fish produced heavier eggs and the egg weight decreased as the spawning season progressed. Based on gonadal cycles, oocyte size frequency distribution and total fecundity, we concluded that silver pomfret is a multiple batch spawner with indeterminate fecundity.     

Female reproductive biology of the sand smelt in brackish lagoons of southern France

The breeding season of Atherina boyeri living in the brackish lagoons of Mauguio, Pérols and Méjean (Hérault, southern France) was very protracted (February-September). The peak of the reproductive effort occurred in April, May and June. Larger fishes started spawning earlier, and stopped later, than smaller ones. Batch fecundity varied from 4 to 447 oocytes and was positively related to female length and weight. Monthly mean fecundity increased at the beginning of the breeding season and decreased between June and July. Individual mean oocyte diameter ranged from 1.34 to 1.94 mm and was not related to fish length. Monthly mean oocyte size declined throughout the breeding season as water temperature rose. There was no trade-off between number and egg size. The strategy of these sand smelts seemed well adapted to ensure spawning success without endangering their survival. The highest reproductive effort period occurred in such a way that environmental conditions were suitable to the best survival and growth of hatched larvae. When breeding ceased, fishes, particularly the youngest ones, had enough time to improve their condition before overwintering.     

Analysis of the cycle of reproduction of Sardina pilchardus (Walbaum, 1792) off the Moroccan Atlantic coast

This work focuses on aspects of reproductive biology of Sardina pilchardus from the Atlantic coast of Morocco. The mean values of batch fecundity estimated for the species is 23150(+/-1301) oocytes for a mean size of 19.5(+/-0.49) cm, the mean relative fecundity being 346(+/-7.34) oocytes per gram of female without ovary. Batch fecundity increases with total length and body weight without ovary. Sizes at first sexual maturity (L50) are reached for males and females at 15.8(+/-0.29) cm and 15.8(+/-0.35) cm, respectively. The spawning period for the population extends between October and July and the spawning peak occurs from October to February. However, the small sardines (14.5-17 cm) in their first reproduction spawn between November and June, whereas larger fish (17.5-25 cm) spawn between October and July. The factor of condition (K) increased in summer during the sexual resting phase. It is weak in winter during the period of reproduction. Regarding, the sex ratio, there was no significant difference in the number of males and females.     

Age, growth and reproduction of Sarcocheilichthys nigripinnis from the Qingyi Stream in the Huangshan Mountains

Identifying the life-history strategies of fish and their associations with the surrounding environment is the basic foundation in the conservation and sustainable utilization of fish species.We examined the age,growth,and reproduction of Sarcocheilichthys nigripinnis using 352 specimens collected monthly from May 2009 to April 2010 in the Qingyi Stream.We found the sex ratio of this study population was 0.58:1(female:male),significantly different from expected 1:1.Females and males both comprised four age groups.The annuli on the scales were formed during February and March.No obvious between-sex difference was observed in length-weight and length-scale-radius relationships.The total length in back-calculation significantly increased with age for both sexes,but did not differ significantly at each age between the two sexes.An inflection point was observed in the growth curves given by the von Bertalanffy growth function for total weight.At this inflection point,fish were 3.95 years.Both sexes reach their 50% sex maturity at age 2,when females and males were 94.7 mm and 103.0 mm total length.The temporal pattern of the gonado-somatic index corresponded to a spawning period that occurred from April through July.The non-synchronicity of egg diameter in each mature ovary during the breeding period suggested these fish may be batch spawners.The absolute fecundity increased significantly with total length and weight,whereas no significant correlation was observed between the relative fecundity and body size.     

武湖日本沼虾繁殖生物学研究

武湖日本沼虾产卵场位于全湖沿岸带．越冬虾主要繁殖期为春夏季(4月中旬～7月中旬,水温20．5～31℃)。当年虾繁殖期为秋季(7月中旬～9月中旬,水温31～23℃),7月中下旬为新老世代交替期．非繁殖季节雄虾多于雌虾,繁殖季节雌虾多于雄虾．越冬虾绝对繁殖力明显大于当年虾．绝对繁殖力与体长呈幂函数关系,与体重呈直线相关．相对繁殖力RW为常数,其95％置信区间为1067．76±16．94eggs·g^-1。     

Reproduction in the greenback grey mullet, Liza subviridis (Valenciennes, 1836)

This paper presents data on the reproductive biology of Liza subviridis , a little studied mullet species. The fish is heterosexual, exhibiting external fertilization. Six maturity stages can be macroscopically identified in the testes and seven in the ovaries. The macroscopic changes in the gonads are manifestations of histological changes occurring in the development of sperm cells and oocytes. First sexual maturity is attained in the length ranges of 9.5–11.5 cm and 10.5–11.5 cm in male and female fish respectively. The fecundity for fish measuring 10.3–13.9 cm in standard length ranged from 40 000–145 000 eggs. The relationship between fecundity ( F ) and length ( L ) can be represented as: F = 1.9044 L ^4.2998. The spawning duration in L. subviridis is restricted to a short and definite period, with all ripe ova being released within a single spawning act. A pronounced spawning season can be detected to extend from June to November. However, during off-seasons, some spawning also occurs. The correlations between spawning, rainfall and air temperature is discussed.     

侧条光唇鱼两邻近地理种群的繁殖生物学特征的差异

2007年7月至2009年6月间,分别于北江中上游及流溪河上游支流采集侧条光唇鱼样本358尾及522尾,对两种群的繁殖生物学特征的差异进行了研究。研究结果显示,两种群雌鱼及雄鱼的最小性成熟年龄均为1 龄,北江种群雌性由1 ~5 龄组成,雄性由1 ~4 组成,性比为雌性：雄性=1:1.73;而流溪河种群雌性由1 ~4 龄组成,雄性由1 ~3 组成,性比为雌性：雄性=1:1.40。北江种群繁殖群体的各年龄组体长及体重均较显著大于流溪河种群。北江种群的繁殖期约为2~10月份,高峰期为3~7月份;而流溪河种群繁殖期为2~8月份,高峰期约为每年的5~7月份;繁殖期内,北江种群雌性及雄性的成熟系数均高于流溪河种群。北江种群各年龄组或体长组的绝对生殖力、体长相对生殖力与体重相对生殖力均极显著地大于流溪河种群。本文结合北江和流溪河在营养状况、捕捞压力及溪流级别上的差异对研究结果进行了分析和讨论。     

Batch fecundity and spawning frequency of invasive Hemiculter leucisculus (Basilewsky, 1855) in Erhai Lake,China

Hemiculter leucisculus are multiple spawners with indeterminate fecundity, although previous fecundity estimates have assumed a determinate spawning pattern. Batch fecundity and spawning frequency of H. leucisculus were studied in Erhai Lake, China, in which the fish, as an exotic species, has become a successful colonizer. Spawning frequency was 16.05 %, as determined from the percent of females with postovulatory follicles 12 to 36 h old during the peak reproductive period (from May 27 to August 8). The average interval between spawning was 6.2 days and there were more than 16 total spawning batches during the peak reproductive period. The average batch fecundity (mean ± SD) was 11,934?±?5,921 hydrated oocytes in 40 females (standard length or SL: 9.1–14.4 cm), while relative batch fecundity was 560?±?137 eggs g^?1 wet weight. The total potential annual fecundity was approximately 190,944 oocytes over the whole spawning season and was much higher than the estimated standing stock (31,585 oocytes) of yolked oocytes (36 females, SL: 9.5–16.2 cm) at the beginning of the spawning season in April 2010. This high annual fecundity is likely to have contributed to successful invasion of Erhai Lake by H. leucisculus.     

Reproductive aspects of the yellowtail snapper Ocyurus chrysurus from the southern Gulf of Mexico

In this study, sex ratio, spawning season, fork length (L(F)) at maturity (L(F50)), batch fecundity and spawning frequency were characterized for the continental population of Ocyurus chrysurus from the Campeche Bank, in the southern Gulf of Mexico. A total of 1657 specimens were collected from February 2008 to January 2009. The overall sex ratio (male:female) and sex ratios by size-class showed no significant differences from an expected 1:1 ratio. The Campeche Bank population did not conform to the reproductive seasonality pattern characteristic of a continental population. A protracted spawning season that extended from January to September with peaks occurring mainly between April and May and additionally in September was observed. The population conformed, however, to the sexual maturity pattern observed for populations and species associated with a continental margin. Fish of both sexes reached the onset of sexual maturity at a similar and small L(F) of c. 14 cm, and L(F50) (L(F) at which 50% of females and males become mature) was 21·3 and 19·4 cm. Asynchronous-type ovarian development was observed for this species and batch fecundity estimates ranged from 14,102 to 164,756 oocytes (mean ±S.D. = 43,852 ± 32,684 oocytes). The overall spawning frequency estimate was once every 8·3 days or 26 times during the 9 month spawning season.     

Reproductive characteristics of pike‐characids Boulengerella cuvieri (Ctenoluciidae) in the middle Xingu River,Eastern Amazon

This study evaluated the reproductive characteristics of pike‐characids, Boulengerella cuvieri, during the hydrological cycle in the Xingu River, eastern Amazon. The sex ratio was 1:1 and the gonado‐somatic index and relative frequency of maturation stages indicate a short breeding season of single phase spawning that coincides with a filling and flood period. Mean standard length at first sexual maturity for female B. cuvieri was estimated to be 22·9 cm.     

Reproduction and growth of Craterocephalus marjoriae and C. stercusmuscarum (Pisces: Atherinidae) in south-eastern Queensland, Australia

SUMMARY. 1. The reproductive cycle and growth of Craterocephalus marjoriae and Craterocephalus stercusmuscarum (Atherinidae) were studied in Brisbane, south-eastern Queensland, over a 17-month period (1981–82).
2. Both species had a 5-month breeding season in spring and summer, with a breeding peak in spring (September-October). Multiple spawning occurred but life time fecundity was not determined.
3. Gonosomatic index values and mean fecundity per female were higher in Craterocephalus marjoriae than in C. stercusmuscarum. Fecundity increased with body length in both species according to the relationship, F=aL^b. Growth rates were similar and growth was adequately described by the von Bertalanffy equation. Both species grew rapidly during the first year and reached maturity the following season. Reproductive strategies are considered in relation to seasonal flooding in the streams inhabited.     

The reproductive traits of Scomber japonicus (Houttuyn, 1782) in the Eastern Adriatic Sea

The aim of the present study was to investigate the fisheries biology of Scomber japonicus (Houttuyn, 1782) in the Adriatic Sea, to enable implementation of appropriate regulatory measures for fisheries. Reproductive biology and sexual patterns of S. japonicus (chub mackerel) were examined from monthly random samples of commercial catches from purse seine nets (10 mm stretched mesh size) in the eastern Adriatic Sea. The annual mean chub mackerel fork length (FL) was examined from 1998 to 2007. Average fork lengths were approximately 25 cm between 1998 and 2002, decreasing to 22 cm between 2003 and 2007. In addition, sex ratios fluctuated as a function of size and month: females were more abundant in the smaller length classes, as well as before and after spawning; males were more abundant in the larger length classes and during spawning. The overall sex ratio was 0.68; females were significantly predominant. 50% of the chub mackerel population was sexually mature at a FL of 18.3 cm, and both males and females reached sexual maturity at FLs of 20.4 cm and 16.8 cm, respectively. Based on gonad maturity stages, gonad weight and gonadosomatic index, chub mackerel spawned from May to August, with peak spawning in June for both sexes. The mean absolute fecundity was 181 277 ± 62 090 oocytes per ovary. A positive exponential correlation was found between fecundity and fork length, gonad weight, and total chub mackerel weight (r² = 0.640; r² = 0.686 and r² = 0.607, respectively).     

Biology of the marbled lungfish, Protopterus aethiopicus Heckel, in Lake Baringo, Kenya

In this paper we provide life history characteristics for an introduced marbled lungfish (Protopterus aethiopicus) population in Lake Baringo, Kenya, including their length–weight relationship, body condition, fecundity, sex ratio, reproduction and food. These data are compared with those of other populations. Samples were obtained from the commercial fishery between January and October 2001. The lungfish exhibited positive allometric growth, with the length–weight relationship described by the equation: logW = ?6.41 + 3.52 logTL. The mean relative condition factor was close to unity, did not vary much between months and was not significantly different between sexes. The overall sex ratio was skewed in favour of females. The size of fish at first maturity was 70–76 cm total length (TL) for females and 82–88 cm TL for males. Fish in maturity stages III–IV occurred in all monthly samples suggesting year round spawning. The marbled lungfish in Lake Baringo is largely piscivorous and its impact on other fishes certainly warrants further research.     

Reproductive biology of Bagrus docmak in the Victoria Nile,Uganda

Aspects of the reproductive biology of Bagrus docmak in the Victoria Nile were investigated between November 2005 and October 2006. Macroscopic and histological analysis of the gonads confirmed it as an asynchronous batch spawner which spawns throughout the year with bimodal spawning peaks coinciding with rainfall seasons. The first spawning peak occurred from March to May, the second from September to November. The sex ratio did not significantly deviate from 1:1. Length at sexual maturity was 33.6 cm and 31.6 cm fork length (FL) for females and males, respectively. Batch fecundity ranged from 1 000 eggs in 34 cm FL fish to 43 000 eggs in 79 cm FL fish, and correlated linearly with FL (r = 0.72) and body weight (r = 0.79). Mean relative batch fecundity was 6 eggs g^?1 (SE 2). These results could guide research into the possibility of artificially inducing the fish to spawn, and its subsequent culture.     

Age,growth and reproduction of the Iranian goby, <Emphasis Type="Italic">Ponticola iranicus</Emphasis> (Perciformes: Gobiidae) from the southern Caspian Sea basin

To estimate reproductive biology of Ponticola iranicus Vasil’eva et al., 2015, in Sefidroud River in the southern Caspian Sea basin age, sex ratio, fecundity, oocytes diameter, gonadosomatic, modified gonadosomatic and dobriyal indices were measured. Regression analyses were used to find relations between fecundity and fish size (length and weight), gonad weight, and age. Mature females and males were longer than 46 and 49 mm in total length, +1 in age. The Von Bertalanffy growth models were L _∞ = 23.00 cm (TL), K = 0.21, t ₀ =–0.25 for all specimens. Sex ratio was 1: 1.32 in favor of males. The average egg diameter was 0.96 mm. The spawning period extended from late February to late April. The averages of absolute and relative fecundity were calculated as 536.9 and 81.3, respectively. The absolute fecundity was significantly related to the body length and weight, as well as gonad weight.     

Reproductive Dynamics and Potential Annual Fecundity of South Pacific Albacore Tuna (Thunnus alalunga)

The reproductive biology of albacore tuna, Thunnus alalunga, in the South Pacific Ocean was investigated with samples collected during broad-scale sampling between 2006 and 2011. Histology was done in a single laboratory according to standard protocols and the data analysed using generalized linear mixed-effects models. The sex ratio of albacore was female biased for fish smaller than approximately 60 cm FL and between 85 and 95 cm, and progressively more male biased above 95 cm FL. Spawning activity was synchronised across the region between 10°S and 25°S during the austral spring and summer where sea surface temperatures were ≥24 °C. The average gonad index varied among regions, with fish in easterly longitudes having heavier gonads for their size than fish in westerly longitudes. Albacore, while capable of spawning daily, on average spawn every 1.3 days during the peak spawning months of October to December. Spawning occurs around midnight and the early hours of the morning. Regional variation in spawning frequency and batch fecundity were not significant. The proportion of active females and the spawning fraction increased with length and age, and mature small and young fish were less active at either end of the spawning season than larger, older fish. Batch fecundity estimates ranged from 0.26 to 2.83 million oocytes with a mean relative batch fecundity of 64.4 oocytes per gram of body weight. Predicted batch fecundity and potential annual fecundity increased with both length and age. This extensive set of reproductive parameter estimates provides many of the first quantitative estimates for this population and will substantially improve the quality of biological inputs to the stock assessment for South Pacific albacore.     

Reproduction of Oligosarcus hepsetus (Cuvier, 1829) (Characiforms) in the Serra do Mar State Park, S?o Paulo, Brazil.

The purpose of this study was to characterize the reproduction of Oligosarcus hepsetus in the Grande river (Santa Virginia Unit - Serra do Mar State Park) based on the reproductive period, length of first gonadal maturation for both sexes, sexual proportion, oocyte development, type of spawn and fecundity. The Grande river was sampled monthly from January through December 2004. The numerical frequency of the stages of maturity and the volumetric method were utilized to determine the reproductive period and fecundity, respectively. The reproduction of Oligosarcus hepsetus was characterized by a long period, relatively low fecundity, precocious length of first gonadal maturation and parceled spawning.     

Reproductive ecology of Japanese anchovy off the Pacific coast of eastern Honshu, Japan

Spawning frequency of offshore migrant populations of Japanese anchovy Engraulis japonicus ranged from 0·34 to 0·90, and was higher than that of inshore Japanese anchovy. In addition, spawning frequency of offshore populations varied in response to the sex ratio. They spawned at water temperatures of 5.0, 8.6 and 12.6° C, indicating that the minimum critical water temperature of offshore Japanese anchovy was considerably lower than that of inshore populations. A significant positive relationship was observed between water temperature and relative batch fecundity of offshore Japanese anchovy. Furthermore, water temperature was negatively related to egg size, suggesting a trade-o. between relative batch fecundity and egg size for offshore fish. At the same water temperature, relative batch fecundity of offshore populations was higher than that of inshore ones. The comparison of spawning frequency and relative batch fecundity suggests that offshore Japanese anchovy represent a reproductive ecology by which they spawn more eggs than inshore Japanese anchovy within a certain time period.     

Reproductive Biology of the Coral-reef Goby, Asterropteryx Semipunctata, in Kaneohe Bay, Hawaii

A population of the Hawaiian coral-reef goby, Asterropteryx semipunctata, was sampled over a 12-month period to determine basic demographics and reproductive parameters. The sexes did not differ in median length or weight, although the largest males were considerably longer and heavier than the largest females. Overall adult sex ratio was 1:1; monthly sex ratios did not differ from unity except in June, when there was a significant female bias. Minimum age at maturity (17.5–19mm SL) was estimated to be 4.5–5 months after hatching. Nearly all fish over 22mm SL were mature. Mature females were found in all months of the year, and females that showed evidence of recent or imminent spawning were collected in every month except December. Gonadal analyses indicated a peak in breeding during the summer (May–July) and minimal spawning during the winter (January–February). Between 20% and 30% of females showed evidence of having spawned within the 24-h period prior to collection; therefore, it was estimated that females spawned, on average, at least once every five days and perhaps as frequently as every three days. Mean batch fecundity was 708 eggs (± 418), and was not well predicted by standard length, body weight, or somatic condition. Relative batch fecundity (mean = 1.44 oocytes mg^–1 somatic wet weight) varied seasonally, with higher values in spring and summer (April–July) than in fall and winter (September–January). Reproductive parameters are compared and contrasted with those of other gobiid fishes to elucidate general differences between temperate and tropical species.