scholarly journals Reproductive biology of Astyanax janeiroensis (Osteichthyes, Characidae) from the Ubatiba River, Maricá, RJ, Brazil

2005 ◽  
Vol 65 (4) ◽  
pp. 643-649 ◽  
Author(s):  
R. Mazzoni ◽  
R. S. Mendonça ◽  
E. P. Caramaschi
Keyword(s):  
Sex Ratio ◽  
Reproductive Biology ◽  
Annual Cycle ◽  
Seasonal Variations ◽  
Standard Length ◽  
Environmental Variables ◽  
Weight Ratio ◽  
Reproductive Period ◽  
Monthly Basis ◽  
Expected Frequency

Aspects of the reproductive biology of Astyanax janeiroensis in the Ubatiba river in Maricá, RJ, Brazil were evaluated in order to ascertain whether the strategy adopted by the species is causally related to environmental variables. Specimens were collected on a monthly basis from October 1994 to September 1995, through electrofishing. The Sex ratio was not significantly different from the expected frequency of 1:1 (G = 1.29; p > 0.50); nonetheless, considering three standard length classes, significantly larger numbers of females were recorded for the higher SL class (G = 11.07; p < 0.01). Size at first maturation showed no significant differences between sexes. Length-weight ratio analyses showed negative allometry for males and isometry, for females. Length structure was significantly different between sexes, suggesting that females are larger than males (D = 0.027, p < 0.01). Reproductive specimens were recorded during nine months of the annual cycle. Seasonal variations of reproductive specimens belonging to two different standard length classes displayed an asynchronous behavior, with larger specimens having a longer reproductive period and smaller ones reproducing for fewer months during the annual cycle. High values of fecundity (F), varying from 3169 to 18714 oocytes, were recorded for fish of 9.1 and 10.2 cm lengths, respectively. The correlation between weight and number of oocytes/unit of weight was positive, indicating that larger specimens produced more eggs.

scholarly journals Population biology of shrimp Macrobrachium jelskii (Miers, 1778) (Decapoda, Palaemonoidea) at the Grande River at northwest of the state of Minas Gerais, Brazil

2012 ◽  
Vol 24 (3) ◽  
pp. 266-275 ◽  
Author(s):  
Samara de Paiva Barros-Alves ◽  
Ariádine Cristine Almeida ◽  
Vivian Fransozo ◽  
Douglas Fernandes Rodrigues Alves ◽  
José Carlos da Silva ◽  
...  
Keyword(s):  
Sex Ratio ◽  
Frequency Distribution ◽  
Population Biology ◽  
Abiotic Factors ◽  
Mesh Size ◽  
Minas Gerais ◽  
Reproductive Period ◽  
Length Frequency Distribution ◽  
Length Frequency ◽  
Monthly Basis

AIM: The population biology of the freshwater shrimp Macrobrachium jelskii was investigated here emphasizing the length-frequency distribution, sex ratio, reproductive period and juvenile recruitment. In addition, the abundance of individuals was correlated with the abiotic factors. METHODS: Samples were collected on a monthly basis from July 2005 to June 2007 along the river margin in shallow water of Grande River, at Planura region, State of Minas Gerais, Brazil (20º 09' S and 48º 40' W), using a trawl net (1.0 mm mesh size, and 2.0 m × 0.5 m wide). The fishing gear was handled by two people along the marginal vegetation of the Grande River in a course of 100 m, covered for one hour. In the laboratory, the specimens were identified, measured and sexed. RESULTS: A total of 2,789 specimens was analyzed, which corresponded to 1,126 males (549 juveniles and 577 adults) and 1,663 females (1,093 juveniles, 423 adults non-ovigerous and 147 ovigerous). The sex ratio differed significantly in favor of the females of M. jelskii (1:1.48; χ² = 103.95; p < 0.0001). The mean size of carapace length (CL) of females (6.32 ± 1.84 mm CL) was statistically higher than of males (5.50 ± 1.07 mm CL) (p < 0.001). The length-frequency distribution of the specimens revealed an unimodal pattern and non-normal distribution for males and females (W = 0.945; p < 0.01). No significant relationship between the abundance of M. jelskii and the environmental variables was observed (p = 0.799). CONCLUSION: The presence of ovigerous females and juveniles in the population suggests a continuous reproduction pattern and recruitment for M. jelskii at Planura region.

Distribution, size and sex composition, reproductive biology and diet of sharks from Northern Australia

1991 ◽  
Vol 42 (2) ◽  
pp. 151 ◽  
Author(s):  
JD Stevens ◽  
KJ McLoughlin
Keyword(s):  
Sex Ratio ◽  
Reproductive Biology ◽  
Annual Cycle ◽  
Post Partum ◽  
Austral Summer ◽  
Size Composition ◽  
Maximum Size ◽  
Northern Australia ◽  
Average Size ◽  
Size At Birth

The distribution, size composition, sex ratio, reproductive biology and diet of 17 species of shark from the families Triakidae, Hemigaleidae and Carcharhinidae from northern Australia were examined. In most of these species the sex ratio of the embryos is 1 : 1, whereas in the post-partum populations there were significantly more males than females. The results indicate four broad reproductive strategies among these sharks. In most species reproduction was distinctly seasonal with individual females giving birth each Austral summer (annual cycle) after a gestation period of 9-12 months. A second group had a very similar cycle except that individual females gave birth every second year (biennial cycle). A third group had an annual cycle but breeding was continuous throughout the year, these were mostly small bottom-associated sharks. One species had a seasonal cycle but gave birth twice each year (biannual cycle) after a 6-month gestation. The average size at birth varied from 27 to 75 cm and the average litter size varied from 2 to 34. The size at birth was about 40% of the size at maturity, which in turn was about 70% of the maximum size. Diets ranged from omnivorous to highly selective. Fish was an important component of the diet in all but one species. There was evidence of partitioning of food resources among sympatric, morphologically similar, sharks.

scholarly journals Seasonal changes in size, sex-ratio and body condition of the damselfishChromis chromisin the central Mediterranean Sea

2014 ◽  
Vol 94 (5) ◽  
pp. 1053-1061 ◽  
Author(s):  
Claudia Bracciali ◽  
Susanna Piovano ◽  
Gianluca Sarà ◽  
Cristina Giacoma
Keyword(s):  
Population Structure ◽  
Sex Ratio ◽  
Body Condition ◽  
Seasonal Changes ◽  
Marine Protected Area ◽  
Reproductive Period ◽  
Rocky Shores ◽  
Central Mediterranean ◽  
Monthly Basis ◽  
Spawning Period

Chromis chromisis one of the most abundant fish species on the Mediterranean rocky shores. Acting as a by-pass of nutrients from the pelagic to the rocky littoral system, it plays an important role as a resource provider and has a relevant function in the community assemblage.Chromis chromishas many of the characteristics required of an indicator species (e.g. it is easy to recognize in the field, small sized, widespread and abundant). In this study we focused on individual size, sex-ratio and body condition in a damselfish population occurring in a central Mediterranean marine protected area. Fishing trials on a monthly basis (April–November) allowed us to assess seasonal changes in population structure. Fish were measured and weighed and a subsample was aged and sexed. On average, males were larger than females. The allometric coefficient,b, for the whole population was 2.99; the maximum age recorded was 7.5 yr. Before reproduction sex-ratio was close to parity (M:F 1:0.78), while a larger proportion of females was captured during the reproductive period. In conclusion, our results show that the population dynamics ofC. chromisis influenced by both sex and size. Since males and females have different behavioural strategies, and since the length of the spawning period is shorter in the smaller than in the larger-sized individuals, this is reflected in temporal changes observed in the population structure.

scholarly journals Reproduction De Heterotis Niloticus (Cuvier, 1829) De La Riviere Agneby (Cote d’Ivoire)

2016 ◽  
Vol 12 (6) ◽  
pp. 83 ◽  
Author(s):  
Kouakou Fokouo Kessia Irène ◽  
Koné Tiéhoua ◽  
Soro Yaya ◽  
N’Da Konan ◽  
Ouattara Mamadou
Keyword(s):  
Sex Ratio ◽  
Reproductive Biology ◽  
Standard Length ◽  
Sexual Maturity ◽  
Condition Factor ◽  
Artisanal Fishing ◽  
Relative Fecundity ◽  
Maturation Stages ◽  
Liver Somatic Index ◽  
Somatic Index

The reproductive biology of Heterotis niloticus has been studied from monthly samples taken from artisanal fishing on the Agneby river during the period june 2013 to May 2015. The whole sample consisted of 498 specimens of which 269 females and 229 males were examined. Sex-ratio observed was in favour of females (1: 1.17; X2 = 3.21; p > 0.05). The monthly evolution of the gonado-somatic index (GSI), the liver-somatic index (LSI), the condition factor (K) and maturation stages suggests that this fish has two periods of reproduction. The two periods were respectively from june to august and from november to december. The standard length at first sexual maturity was 490.6 mm for females and 436.3 mm for males. The absolute fecundity was ranged from 5424 to 25591 oocytes in females of 595 mm to 780 mm standard length. The relative fecundity was 3752± 1491 oocytes/kg of female.

scholarly journals Reproduction of Hypoptopoma inexspectatum (Holmberg, 1893) (Siluriformes, Loricariidae) in the Southern Pantanal Floodplain, Upper Paraguay River Basin, Brazil

2020 ◽  
Author(s):  
M. J. Pereira ◽  
L. F. Viana ◽  
M. H. B. Sais ◽  
Y. R. Súarez
Keyword(s):  
Sex Ratio ◽  
River Basin ◽  
Reproductive Biology ◽  
Standard Length ◽  
Relative Fecundity ◽  
Absolute Fecundity ◽  
Weight Relationship ◽  
Paraguay River

Abstract This work aimed to describe the reproductive biology of Hypoptopoma inexspectatum in southern Pantanal. A total of 538 individuals were sampled and analyzed from February 2009 through January 2011 in southern Pantanal. We did not observe differences in sex-ratio, and both sexes presented positive allometric length/weight relationship (LWR). Reproduction occurs mainly from January to February. Females reached first maturation (L50) with 37.80 mm and males with 45.80 mm. Absolute fecundity is estimated in mean=177.43 (sd±127.06) oocytes and relative fecundity in 3.12 (sd±2.23) oocytes/mg. Fecundity is positively correlated with standard length (Spearman r= 0.43; p=0.013), and total spawning is a used spawning strategy for H. inexspectatum.

scholarly journals Iheringichthys labrosus (Siluriformes: Pimelodidae) in the Piquiri River, Paraná, Brazil: population structure and some aspects of its reproductive biology

2009 ◽  
Vol 7 (1) ◽  
pp. 55-64 ◽  
Author(s):  
Arlei J. Holzbach ◽  
Éder A. Gubiani ◽  
Gilmar Baumgartner
Keyword(s):  
Population Structure ◽  
Sex Ratio ◽  
Reproductive Biology ◽  
Standard Length ◽  
Length Distribution ◽  
Temporal Distribution ◽  
Spatial And Temporal Distribution ◽  
Night Time ◽  
Reproduction Period ◽  
Iheringichthys Labrosus

The purpose of this study was to analyze the population structure (spatial and temporal distribution, sex ratio, length distribution and length/weight relationship) and reproductive biology of Iheringichthys labrosus. This species is of importance as fisheries resource in the Paraná River basin. Fish were sampled, bimonthly, with gill and trammel nets at three sampling sites (Campina, Apertado and Altônia), located in the Piquiri River, between November 2002 and September 2003. In this study, 164 individuals were collected; the largest capture occurred in Campina site, with 209.88 individuals/1000 m² of net for 24 hours, while the shift of largest capture was night time (N) and the month was July. Females occurred in larger numbers than males in all periods. The growth was allometric positive and the reproduction period was from the beginning of September to the end of December, with the majority of the individuals showing a standard length between 13.0 and 20.0 cm.

Reproductive characteristics of the sand sole Pegusa lascaris (Soleidae), from the eastern-central Atlantic

2008 ◽  
Vol 88 (3) ◽  
pp. 629-635 ◽  
Author(s):  
José G. Pajuelo ◽  
José M. Lorenzo
Keyword(s):  
Sexual Dimorphism ◽  
Sex Ratio ◽  
Reproductive Biology ◽  
Standard Length ◽  
Spawning Season ◽  
Significant Difference ◽  
Males And Females ◽  
First Maturity ◽  
Central Atlantic ◽  
Size At First Maturity

The reproductive biology of 1318 sand sole, Pegusa lascaris, was investigated. This species is a gonochoristic species with no evidence of sexual dimorphism. The overall sex-ratio was 1 male to 0.92 females. Females predominate in the larger size intervals, with a significant difference in mean standard length and range between sexes. Size at first maturity for males and females is attained at 17.2 and 17.7 cm standard length, respectively. Vitellogenesis does not begin synchronously for all females, as a consequence the spawning season appears to be continuous. In each female spawning takes place in two batches which are spawned mainly in spring and autumn, indicating that fish are serial synchronous spawners.

scholarly journals Some aspects of the reproductive biology and sex-ratio of Cirrhina reba (Hamilton) (Cyprinidae : Cypriniformes)

2012 ◽  
Vol 30 ◽  
pp. 21-24
Author(s):  
Sarmin Akther ◽  
Shirin Akther
Keyword(s):  
Sex Ratio ◽  
Reproductive Biology ◽  
Standard Length ◽  
Total Weight ◽  
Chi Square ◽  
Male And Female ◽  
Total Length ◽  
Chi Square Test ◽  
Somatic Index

Some aspects of the reproductive biology viz. sex-ratio gonadal length index (G.L.I.), gonado somatic index (G.S.I.) and sex-ratio of Cirrhina reba were studied during September 2004 to July 2005. In present study the highest values of GLI (33.76) and GSI (0.63) were in the month of July. Total length (TL) and gonadal length (GL), total weight (TW) and gonadal weight ( GW ), standard length (SL) and gonadal length ( GL ) and gonadal weight relationships were found to be positive; and the relationships were: GL = -3.873 + 0.219 TL (r = 0.992), GW = 0.01511+0.000815 TL (r = 0.979), GL = -2.6030+0.253 SL (r = 0.990), GL = 0.01997+0.000938 SL (r= 0.976), GW = 13.2952+0.6064 TW (r = 0.958), GW = 0.0772+0.00233 TW (r = 0.979). The sex- ratio of C. reba were 1:1.62 for male and female respectively. The Chi-square test showed significant differences of sex-ratio among months and totals.DOI: http://dx.doi.org/10.3329/ujzru.v30i0.10739Univ. j. zool. Rajshahi Univ. Vol. 30, 2011 pp. 21-24

scholarly journals Reproductive biology of the Neotropical electric fish Brachyhypopomus draco (Teleostei: Hypopomidae) from southern Brazil

2009 ◽  
Vol 7 (4) ◽  
pp. 737-744 ◽  
Author(s):  
Andrea B. Schaan ◽  
Júlia Giora ◽  
Clarice B. Fialho
Keyword(s):  
Sexual Dimorphism ◽  
Sex Ratio ◽  
Reproductive Biology ◽  
Water Depth ◽  
Electric Fish ◽  
Gonadosomatic Index ◽  
Reproductive Period ◽  
Weakly Electric Fish ◽  
Hepatosomatic Index ◽  
Southern Brazil

The reproductive biology of a population of the weakly electric fish Brachyhypopomus draco from southern Brazil is described. Information is provided on the establishment of the reproductive period in this species and its relations with environmental and feeding factors, as well as on the absolute and relative fecundities, spawning type, sex ratio and sexual dimorphism. The species exhibits a relatively long reproductive period, a relative fecundity of 0.173 oocytes per mg of female total weight, and fractional spawning. The sex ratio did not differ from 1:1 during all sampled months. Sexual dimorphism related to hypertrophy of the male's distal portion of caudal filament was observed and males grew to greater lengths than females. Male gonadosomatic index (GSI) was significantly related to water depth, oxygen saturation and temperature. Female GSI was significantly related to water depth and hepatosomatic index.

scholarly journals Reproductive Biology of the Mola Carplet Amblypharyngodon mola (Hamilton) (Cypriniformes: Cyprinidae) from Netrakona Water

1970 ◽  
Vol 44 (3) ◽  
pp. 377-379 ◽  
Author(s):  
Bimal Kanta Saha ◽  
M Rafiqul Islam ◽  
Aparna Saha ◽  
M Altaf Hossain
Keyword(s):  
Sex Ratio ◽  
Key Words ◽  
Reproductive Biology ◽  
Standard Length ◽  
Mean Value ◽  
Total Weight ◽  
Total Length ◽  
The Mean

Some aspects of the reproductive biology viz. sex ratio, fecundity and reproductive periodicity of Amblypharyngodon mola were studied during March 2004 through February 2005 in Netrakona. Sex ratio was found to be 1:2.03. Fecundity varied from 1,291 to 12,797 with a mean value 5,751.46 ± 3,321.73 eggs. The relationships between Fecundity (F) and Total Length (TL), Standard Length (SL), Total Weight (TW), Gonadal length (GL) and Gonadal Weight (GW) were calculated and found to be highly significant. The mean of ova diameter was 1.4 ± 0.35mm. Different methods used to study the reproductive periodicity showed that the periodicity of A. mola starts from March and continues up to August with a peak in May. Key words: Reproductive biology, Reproductive periodicity, Amblypharyngodon mola. DOI: 10.3329/bjsir.v44i3.4414 Bangladesh J. Sci. Ind. Res. 44(3), 377-379, 2009   

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