scholarly journals Seasonal variations in the population biology of Salmostoma bacaila (Cyprinidae) from a tributary of the Payra River, Bangladesh

2019 ◽  
pp. 113-119
Author(s):  
Ahamed Ahamed ◽  
Faruque Ahmed Zoarder ◽  
Jun Ohtomi
Keyword(s):  
Sex Ratio ◽  
Seasonal Variations ◽  
Population Biology ◽  
Sexual Maturity ◽  
Condition Factor ◽  
Gonadosomatic Index ◽  
Spawning Season ◽  
Frequency Distributions ◽  
Size At Sexual Maturity ◽  
Management And Conservation

Some biological parameters of Salmostoma bacaila – including sex ratio, length-frequency distributions (LFDs), size at sexual maturity, spawning season, length-weight relationships (LWRs) and condition factor – were studied. Samples were collected seasonally during June 2017 to May 2018 from a tributary of the Payra River. The overall sex ratio was significantly different from the expected value of 1:1 (p < 0.001), in favour of male specimens. Females were significantly larger than males. Size at sexual maturity was estimated at 7.6~7.7 cm total length. Seasonal variations in the gonadosomatic index (GSI) indicate that the main spawning season is from spring to summer. The LWRs showed negative allometric growth in both sexes, but with clear seasonal variation. Fulton’s condition factor varied in both sexes and was attributed to variations in GSI with maturity. The fin¬dings of this study will be helpful for management and conservation of S. bacaila populations.

scholarly journals Population biology of Uca mordax (Smith, 1870) (Crustacea, Decapoda, Ocypodidae) from the southeastern coast of Brazil

2009 ◽  
Vol 31 (73/75) ◽  
Author(s):  
Vivian Fransozo ◽  
Rafael Campanelli Mortari ◽  
Aline Staskowian Benetti
Keyword(s):  
Sex Ratio ◽  
Population Biology ◽  
Sexual Maturity ◽  
Fiddler Crab ◽  
Carapace Width ◽  
Southeastern Coast ◽  
Size Classes ◽  
Median Size ◽  
Size At Sexual Maturity ◽  
Males And Females

The population biology of the fiddler crab Uca mordax (Smith, 1870) was investigated in an estuarinemangrove from the southeastern coast of Brazil. Samplings were monthly performed by 2 collectors for30 min. using the technique of capture per unit effort during low tide periods. The allometric techniquewas used to determine crab size at sexual maturity (males and females). Thus, specimens were classified into juveniles and adults according to their size at sexual maturity for each sex. The specimens weredistributed into size classes. Recruitment was based on the juvenile frequency and the reproduction peakin ovigerous females. The median size of males was 15.9 ± 2.7 mm carapace width (CW) (n = 557) andthat of females, 14.6 ± 2.8 mm CW (n = 528). At sexual maturity, size of crabs was 11.9 mm CW formales and 11.5 mm CW for females. Juveniles were found throughout the year but more frequently inthe winter and autumn. Sex ratio did not differ among seasons, except during the summer (p < 0.05).As regards sex ratio per size class, females predominated in the fi rst size classes. Reproduction peakwas observed in the summer. In short, the population biology of U. mordax was similar to that of mostbroad-front fi ddler crab species.

scholarly journals Length-weight relation, condition factor and gonadosomatic index of the whitemouth croaker, Micropogonias furnieri (Desmarest, 1823) (Actinopterygii: Sciaenidae), caught in Lençóis Bay, state of Maranhão, eastern Amazon, Brazil

2017 ◽  
Vol 65 (1) ◽  
pp. 1-8 ◽  
Author(s):  
James Werllen de Jesus Azevedo ◽  
Antonio Carlos Leal de Castro ◽  
Marcelo Henrique Lopes Silva
Keyword(s):  
Sex Ratio ◽  
Rainy Season ◽  
Condition Factor ◽  
Gonadosomatic Index ◽  
Length Distribution ◽  
The State ◽  
Allometric Growth ◽  
First Semester ◽  
Length Relationship ◽  
Micropogonias Furnieri

Abstract The whitemouth croaker, Micropogonias furnieri, which is exploited off the state of Maranhão, Brazil, reinforces the need for maintenance programs of natural stocks of this species to assist in the management of this exploited resource. The aim of the present study was to describe aspects regarding its reproductive characteristics (gonadosomatic index and condition factor) and also the length distribution and weight-length relationships. The fish were caught in Lençóis Bay in the state of Maranhão (eastern Amazon) between June 2010 and July 2011. A total of 570 individuals were caught (318 males and 252 females). Differences in length were found between the sexes, with females larger than males. The sex ratio indicated a tendency for females to be more abundant in the rainy season (first semester), whereas males predominated in the dry season (second semester). The weight-length relationship indicated negative allometric growth for both sexes. The analysis of the variation in the condition factor suggests that lower values coincided with higher gonadosomatic index values and that this factor is a good reproductive indicator for M. furnieri in the region.

A population study of Galathea intermedia (Crustacea: Decapoda: Anomura) in the German Bight

2003 ◽  
Vol 83 (1) ◽  
pp. 133-141 ◽  
Author(s):  
Katrin Kronenberger ◽  
Michael Türkay
Keyword(s):  
Sex Ratio ◽  
Population Biology ◽  
Abdominal Segment ◽  
Morphological Characters ◽  
Adult Males ◽  
Length Frequency ◽  
Relative Growth ◽  
Frequency Distributions ◽  
Squat Lobster ◽  
Growth And Reproduction

The objectives of this study were to assess population biology and dynamics of the squat lobster Galathea intermedia. On the basis of nearly regular monthly samples taken with a 2-m beam trawl in the Helgoland trench (HTR) during the period of 1985 until 1992, sex ratio, length composition, relative growth and reproduction were studied. The overall sex ratio deviates significantly from 1:1 with 1[male ]:1·8[female] (P[les ]0·001). On average, sexes are equally large, but adult females attain a slightly larger size than adult males. No sex-specific differences in the length–weight relationship were found. Relative growth of the first abdominal segment is clearly of sexual-dimorphic character. On the basis of the length–frequency distributions, the life cycle of the HTR population lasts between one and two years. According to the appearance of ovigerous females and juveniles, reproduction and recruitment are clearly seasonal. Recruitment takes place between July and December. The main reproduction begins in April and ends in September, with a peak between June and August. A significant increase of specimens showing both male and female morphological characters, referred to as morphological hermaphrodites (P[les ]0·001), and males (P[les ]0·05) respectively, was detected.

scholarly journals Population structure and reproductive cycle of the commercial sea cucumber Holothuria mexicana in Belize

2018 ◽  
Vol 66 (4) ◽  
Author(s):  
Arlenie Rogers ◽  
Jean-François Hamel ◽  
Annie Mercier
Keyword(s):  
Sex Ratio ◽  
Protected Areas ◽  
Reproductive Cycle ◽  
Sexual Maturity ◽  
Sea Cucumber ◽  
Size Structure ◽  
Natural Populations ◽  
Gonad Index ◽  
Size At Sexual Maturity ◽  
Spawning Periods

The population and reproductive biology of the commercial sea cucumber Holothuria mexicana (Ludwig, 1875) was studied in Southern Belize (Caribbean Sea), including the sex ratio, size at sexual maturity and reproductive cycle, as well as the size structure among habitats located inside and outside protected areas. Individuals found inside marine protected areas were consistently larger than individuals found outside these boundaries. The male:female sex ratio was 1.1:1.0 with a unimodal size distribution composed mainly of sexually mature individuals (87 %). Size at sexual maturity was established to be ~10 cm based on measures of gamogenetically mature individuals during the peak of the gametogenic maturity period. Juveniles and small adults measuring ≤ 15 cm (13 %), were collected exclusively in sandy and muddy areas of seagrass habitats associated with mangroves. Larger adults were commonly found on hard substrates in both seagrass-associated and coral-reef-associated habitats. Based on histology and gonad indices, the first sign of early gametogenesis was detected in August in both sexes. Gametes developed and matured throughout the colder months between November and February. Decreases in gonad index in both years suggest annual spawning, starting in March-April 2014 (single major event) and March-April and July-August 2015 (two smaller events) for both males and females. The spawning periods were correlated with warmer or increasing temperatures, low rainfall and increasing or high chlorophyll-a concentrations. These data will hopefully guide management and protection of the natural populations of H. mexicana, which are already suffering from overfishing in Belize and neighboring countries. 

scholarly journals Reproductive Phenology and Size Structure Characteristics of Hypseleotris agilis (Herre, 1927) in Lake Mainit, Philippines

2020 ◽  
Vol 80 ◽  
pp. 35-42
Author(s):  
Joycelyn C. Jumawan ◽  
Paula Marie Hidalgo ◽  
Romell A. Seronay
Keyword(s):  
Native Species ◽  
Condition Factor ◽  
Size Structure ◽  
Gonadosomatic Index ◽  
Reproductive Phenology ◽  
Hepatosomatic Index ◽  
Fishery Resource ◽  
Gravid Females ◽  
Management And Conservation

Hypseleotris agilis locally known as Bugwan is a native species and one of the most abundant fishes of commercial value in Lake Mainit, Philippines. A total of 1,584 H. agilis from Lake Mainit near the mouth of Kalinawan and Puyo River were caught from May 2018 to February 2019 to determine the length-weight relationship (LWR), condition factor (K), gonadosomatic index (GSI) and hepatosomatic index (HSI) of this species. Positive allometric growth was observed for both sexes (b>3). Sex ratio indicated the dominance of males over females as much as 58.7%. The number of ripe males and gravid females was observed throughout the months of the collection, which indicates the ability of the fish species to spawn continuously throughout the year. Determination of GSI in both sexes showed higher values during November (males) and December (females). However, HSI values were relatively low during the spawning season, which would indicate the usage of energy for gonadal maturation. The K factor showed high values during the peak spawning months, directly proportional to GSI values. This study provides updated information for management and conservation of this important fishery resource in Lake Mainit.

Reproductive cycle of the blue jack mackerel, Trachurus picturatus (Bowdich, 1825), off the Portuguese continental coast

2019 ◽  
Vol 32 ◽  
pp. 14
Author(s):  
Ana Maria Costa
Keyword(s):  
Sex Ratio ◽  
Reproductive Biology ◽  
Condition Factor ◽  
Stock Assessment ◽  
Gonadosomatic Index ◽  
Biological Information ◽  
Hepatosomatic Index ◽  
Jack Mackerel ◽  
First Time ◽  
Monthly Variations

This work provides for the first time a description of the reproductive biology of Trachurus picturatus in Portuguese continental waters (between 41° 49′ and 36° 57′ latitude North). From January 2010 to December 2016 a total of 7409 individuals were sampled from bottom trawlers operating on the northwestern coast of Portugal. The observed sex ratio was 0.56 in favor of the females. Monthly variations in gonadosomatic index, proportion of actively spawning individuals, hepatosomatic index and Fulton′s condition factor were analyzed. More than 60% of spawning individuals were recorded in the first quarter, corresponding to the highest values of GSI, and Fulton's K and hepatosomatic index increased after the start of spawning. The morphometric relationships between total length and gutted weight showed significant correlations (high determination coefficient, r2 > 0.9) and isometric growth (b = 3) for both sexes. Results indicate that the spawning season of T. picturatus starts in December and extends until April–May, with a peak in March, which agrees with what has been indicated by other authors for the northeast Atlantic. This work provides important biological information on a species that although not subject to stock assessment is currently the 5th species landed by weight in Portuguese continental waters.

Reproductive biology of thin sharpbelly, Toxabramis swinhonis Günther, 1873 in a shallow lake (Biandantang Lake) along the middle reach of the Yangtze River basin (China): implications for fisheries management

2019 ◽  
Vol 55 ◽  
pp. 8
Author(s):  
Xianghong Dong ◽  
Gaël Grenouillet ◽  
Tao Ju ◽  
Tao Xiang ◽  
Zhan Mai ◽  
...  
Keyword(s):  
Sex Ratio ◽  
Reproductive Biology ◽  
Early Stage ◽  
Yangtze River Basin ◽  
Gonadosomatic Index ◽  
Bimodal Distribution ◽  
Spawning Season ◽  
Central China ◽  
High Fecundity ◽  
Wide Range

The reproductive biology of Toxabramis swinhonis, one of the most abundant bycatch species in freshwater fishery in China, was first reported based on 783 specimens collected in Biandantang Lake, central China from October 2016 to September 2017. The overall sex ratio (female/male) was 1.03:1, not significantly different from the expected value 1:1. Nevertheless, sex ratio varied with seasons: 1.32:1 in the early stage of the spawning season (March–April), while 0.46:1 in the later stage (July–August). The monthly succession of the average gonadosomatic index (GSI) and percentages of mature individuals co-indicated that T. swinhonis was a spring-summer (March–August) spawner. Further, the bimodal distribution of the size of eggs from one gravid ovary and histological analysis of mature gonads suggested that T. swinhonis was a multiple spawner with indeterminate fecundity and high degree of spawning asynchronicity. The sizes and ages at first maturity for females and males were 84.47 and 81.86 mm, and 1.62 and 1.56 yr, respectively. The batch fecundity (FB) of this species varied in a wide range from 2006 to 73592 eggs per fish with a mean value of 26487.15 ± 2675.61 (S.E.) eggs and increased with the increasing of the gonad weight (WG), eviscerated weight (WE), total length (LT) and age (A). Overall, T. swinhonis in Biandantang (BDT) Lake is characterized by high fecundity and prolonged spawning season, resulting in easy population explosion. Thus, to remove T. swinhonis moderately or release predator fish discreetly to control its population is proposed considering its reproductive characteristics.

scholarly journals Influence of the flood pulse on the reproduction of Tocantinsia piresi (Miranda Ribeiro) and Auchenipterus nuchalis (Spix & Agassiz) (Auchenipteridae) of the middle Xingu River, Brazil

2015 ◽  
Vol 75 (3 suppl 1) ◽  
pp. 158-167 ◽  
Author(s):  
TMS. Freitas ◽  
BS. Prudente ◽  
VA. Oliveira ◽  
MNC. Oliveira ◽  
EG. Prata ◽  
...  
Keyword(s):  
Sex Ratio ◽  
Condition Factor ◽  
Gonadosomatic Index ◽  
Flood Pulse ◽  
Allometric Growth ◽  
Xingu River ◽  
Ratio Size ◽  
Flood Period ◽  
First Maturity ◽  
Size At First Maturity

Abstract This study investigates the influence of the flood pulse on the reproductive biology of the auchenipterids Tocantisia piresi (Miranda Ribeiro, 1920) and Auchenipterus nuchalis (Spix & Agassiz, 1829) from the middle Xingu River in the Brazilian state of Pará. The specimens were collected every three months between April, 2012, and January, 2014, covering four distinct periods (flood, ebb, dry, and filling). The sex ratio, size at first maturity, gonadosomatic index, and condition factor were analysed in the two species, and evaluated in the context of the different hydrological periods. A total of 897 specimens of T. piresi were collected, of which 467 were female, and 430 males, and 383 A. nuchalis (286 females and 97 males). In T. piresi, the sex ratio was biased only in the filling and ebb periods, whereas in A. nuchalis, it departed significantly from the expected ratio of 1:1 in all periods, with a predominance of females. The female T. piresi mature at a smaller size than the males, with the opposite of the pattern being recorded in A. nuchalis. In T. piresi, the breeding peak was observed during the low water periods, whereas in A. nuchalis, the peak was recorded in the flood periods. Male and female T. piresi presented similar positively allometric growth rates, whereas in A. nuchalis, growth was negatively allometric, but rates were different between genders. A higher condition factor was recorded in the females of both species during the ebb period. Overall, the results of this study reveals distinct flood pulse effects on the reproductive parameters of the two auchenipterid species studied; for A. nuchalis the spawning seems to happen at the flood period and for T. piresi at the dry season of the middle Xingu River.

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