scholarly journals Population structure, condition factor and reproductive period of Astyanax paranae (Eigenmann, 1914) (Osteichthyes: Characidae) in a small and old Brazilian Reservoir

2008 ◽  
Vol 51 (3) ◽  
pp. 503-512 ◽  
Author(s):  
Milza Celi Fedatto Abelha ◽  
Erivelto Goulart
Keyword(s):  
Population Structure ◽  
Sex Ratio ◽  
Total Population ◽  
Condition Factor ◽  
Regression Coefficient ◽  
Population Sample ◽  
Reproductive Period ◽  
Small Reservoir ◽  
Structure Condition ◽  
Maximum Value

The population structure, condition and reproductive period of Astyanax paranae adult individuals inhabiting a small reservoir were investigated. The fishes were quarterly captured from the riverine and lacustrine zones of the Alagados Reservoir, Paraná, Brazil, during 1996/1997 and 1998/1999. The sex ratio differed from 1:1 with the predominance of the females in all standard length classes and total population sample. The females showed higher condition than the males. Both the sexes presented lower mean condition values in April and higher mean condition values in July. The estimated values of the regression coefficient indicated isometric growth for the females and males. The gonadosomatic relationship reached a maximum value of 14.80% for the females and 8.43% for the males. The reproductive period possibly occurred from October to April.

scholarly journals Population structure and reproductive biology of Cichla kelberi (Perciformes, Cichlidae) in Lobo Reservoir, Brazil

2008 ◽  
Vol 6 (2) ◽  
pp. 201-210 ◽  
Author(s):  
Jussara E. de Souza ◽  
Evelise N. Fragoso-Moura ◽  
Nelsy Fenerich-Verani ◽  
Odete Rocha ◽  
José R. Verani
Keyword(s):  
Sex Ratio ◽  
Condition Factor ◽  
Reproductive Activity ◽  
Reproductive Period ◽  
High Fecundity ◽  
Long Period ◽  
Total Length ◽  
Relative Condition Factor ◽  
Central Value ◽  
Large Output

The structure of Cichla kelberi population was characterized regarding the sex ratio, total length composition and some reproductive characteristics. The specimens were collected in two periods, from November 2002 to November 2003 and from December 2004 to May 2006. The sex ratio was significantly different than 1:1. The total length varied from 3.4 to 40.1 cm, with individuals in the shortest length classes occurring throughout the year, but with greater incidence in the warmer periods. Females and males reached similar lengths and there was no difference between the sexes regarding the length-weight relationship. The estimated values of condition factor were near the central value of 1.0 and decreased during the cooler months, coinciding with periods of lower reproductive activity. Individuals with mature or semi-spent gonads occurred from November to April, indicating that Cichla kelberi reproduces for a long period of time. The spawning is partitioned, with an average absolute fecundity of 6072 oocytes (from 5220 to 6908 oocytes). The high relative condition factor values, long reproductive period, large output of fingerlings and high fecundity are biological conditions that indicate the species is well adapted in this reservoir.

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 Population structure and reproductive behavior of Sinaloa cichlid Cichlasoma beani (Jordan, 1889) in a tropical reservoir

2011 ◽  
Vol 9 (3) ◽  
pp. 593-599 ◽  
Author(s):  
Melgen A. García-Lizárraga ◽  
Francisco Enrique Soto-Franco ◽  
Javier Marcial de Jesús Ruiz Velazco-Arce ◽  
José Iván Velázquez-Abunader ◽  
Jorge Saúl Ramírez-Pérez ◽  
...  
Keyword(s):  
Population Structure ◽  
Sex Ratio ◽  
Multinomial Distribution ◽  
Mesh Size ◽  
Condition Index ◽  
Reproductive Period ◽  
Tropical Reservoir ◽  
Timing Of Reproduction ◽  
First Maturity ◽  
Size At First Maturity

The population structure and reproductive condition of the Sinaloa cichlid Cichlasoma beani from samples obtained from June 2000 to July 2001 were determined. Samples in the first week each month from the largest trader of tilapia in the Aguamilpa Reservoir in Mexico and were caught in gillnets (9.6 and 11.4 cm stretch-mesh size). Of 596 specimens, there were 427 males and 169 females; monthly sex ratio, frequency of lengths by the multinomial distribution, timing of reproduction, condition index, and size at first maturity was determined. Differences in the sex ratio and monthly totals were significant, favoring males, except for September 2000 and March 2001. From one (August 2000) to three modal groups (July 2000 and June 2001) were identified by size. There were no significant differences in standard length weight relationships by sex, which indicated that a shared model for both genders is appropriate, and isometric growth was detected. Based on the proportion of mature and partially matures fish, the main reproductive period was April through June; size at first maturity was 18.9 cm. Water temperature was not significantly related to the percentage of mature and partially matures Sinaloa cichlids or spawning. These findings provide information for regulating the Cichlasoma beani fishery in this region such minimum legal size and non-fishing period.

scholarly journals RELATIVE GROWTH OF CARDISOMA CRASSUM SMITH, 1870 (DECAPODA: GECARCINIDAE) IN THE ESTUARY EL SALADO, PUERTO VALLARTA, JALISCO MEXICO

2018 ◽  
Vol 11 (41-42) ◽  
Author(s):  
Madeline Getzemani Molina-Ortega ◽  
Horacio Vázquez-López
Keyword(s):  
Growth Rate ◽  
Sex Ratio ◽  
Condition Factor ◽  
Mangrove Forests ◽  
Allometric Growth ◽  
Crab Species ◽  
Eastern Tropical Pacific ◽  
Relative Growth ◽  
Maximum Value ◽  
Huxley Equation

The growth of organisms is accompanied by changes in proportion and size, and it is known as relative or allometric growth. C. crassum is one of the largest crab species it inhabits mangrove forests in the Eastern tropical Pacific, however, the data of this specie is deficient and limited to a few records. Therefore, the aim of this work was to estimate the growth of C. crassum in El Salado stream, Puerto Vallarta, Jalisco, Mexico. A total of 252 organisms were captured in the rainy season, which were marked and released after assessments. The Huxley equation was used to determine allometry and to estimate the condition factor (K) and the growth rate. The sex ratio was 1:1.72, favoring females. The range of the condition factor in females was between 0.02 and 0.06 g/cm3. In ovigerous females the K mínimum value was 0.03 and the maximum value was 0.08 g/cm3; for males the K minimum was 0.03 and the maximum was 0.14 g/cm3. A K=0.88 was obtained and Lmax=95.1 mm. There were no significant differences in CA between sexes, neither in PO. While differences could be observed in LQ and AQ between sexes. It was concluded that C. crassum growth is similar to another gecarcinid species in El Salado. Males reach larger sizes than females and the condition factor is similar between males and non-ovigerous females, but there are significant differences between the condition factor in females and ovigerous females.<br /><br />

scholarly journals Population structure, condition and diet of Oligosarcus paranensis (Menezes & Gery, 1983) (Osteichthyes: Characidae) at two reservoirs in South Brazil

2012 ◽  
Vol 12 (1) ◽  
pp. 187-197 ◽  
Author(s):  
Milza Celi Fedatto Abelha ◽  
Elaine Antoniassi Luiz Kashiwaqui ◽  
Erivelto Goulart
Keyword(s):  
Population Structure ◽  
Sex Ratio ◽  
Standard Length ◽  
Volumetric Method ◽  
Population Parameters ◽  
Allometric Growth ◽  
Structure Condition ◽  
Food Items ◽  
Plant Matter ◽  
South Brazil

This study investigated the population parameters, condition and diet of Oligosarcus paranensis at Fiú and Mourão Reservoirs, located in Paraná State, Brazil. The fishes were collected quarterly between 1996/1997 and 1998/1999 using gillnets. Food items were quantified by volumetric method. The specimens at Fiú showed comparatively smaller length and worse condition. Sex ratio was statistically equal to 1:1 at Mourão, whereas there was a significant predominance of males at Fiú. Sex ratio also varied among size classes. Allometric growth prevailed among the studied groups. The diet consisted mainly of fishes and was complemented with invertebrates and plant matter in both reservoirs. There was a change in the feeding pattern as the standard length increased. Fishes changed from invertivores to piscivores, except for males in Mourão, for which a reverse trend occurred.

scholarly journals Population structure and reproductive biology of Loricariichthys melanocheilus Reis & Pereira, 2000 (Siluriformes: Loricariidae) in the rio Ibicuí, Brazil

2015 ◽  
Vol 13 (2) ◽  
pp. 371-382 ◽  
Author(s):  
Éverton Luís Zardo ◽  
Everton Rodolfo Behr
Keyword(s):  
Population Structure ◽  
Sex Ratio ◽  
Reproductive Biology ◽  
Condition Factor ◽  
Gonadosomatic Index ◽  
Maturity Stage ◽  
Allometric Growth ◽  
Males And Females ◽  
Lotic Environments ◽  
Gonadal Condition

The objective of this study was to analyze population structure (spatial distribution, seasonal distribution and distribution by length classes, sex ratio and length-weight relationship) and aspects of the reproductive biology of Loricariichthys melanocheilus. Fish were sampled bimonthly using gillnets and trammel nets in lentic and lotic environments in the rio Ibicuí, between the years 2000 and 2001. Were collected 410 specimens: 230 females, 164 males and 16 specimens whose sex could not be determined. A greater number of specimens were collected in October/November and December/January and in lentic environments. The greater length classes had a higher amount of females (p < 0.05) and the sex ratio in all sampling periods was 1.38 females per male. Both males and females showed positive allometric growth (b = 3.299 and b =3.487, respectively). The highest values for gonadosomatic index (GSI) and gonadal condition factor (K) were observed from August/September and peaked in October/November, just like the highest frequencies of females at maturity stage C (mature), which is indicative that the breeding season occurs at this time.

scholarly journals Seasonal changes in the gonadossomatic index, allometric condition factor and sex ratio of an auchenipterid catfish from eastern Amazonia

2011 ◽  
Vol 9 (4) ◽  
pp. 839-847 ◽  
Author(s):  
Tiago Magalhães da Silva Freitas ◽  
Vitor Hudson da Consolação Almeida ◽  
Luciano Fogaça de Assis Montag ◽  
Rossineide Martins da Rocha ◽  
Nelson Ferreira Fontoura
Keyword(s):  
Sex Ratio ◽  
Condition Factor ◽  
Seasonal Pattern ◽  
Gonadosomatic Index ◽  
Reproductive Period ◽  
Complete Data ◽  
Conservation Strategies ◽  
Data Set ◽  
Raw Data ◽  
Reproductive Process

The aim of the present study was to evaluate the seasonal pattern of the gonadosomatic index (GSI), condition factor (K), and sex ratio in the catfish Auchenipterichthys longimanus (Siluriformes: Auchenipteridae) as an approach to identify its reproductive period. A total of 589 A. longimanus specimens (251 males and 338 females) were captured in the rivers of the Caxiuanã National Forest, in the Brazilian state of Pará, between July, 2008 and July, 2009. Among the male specimens, 171 were classified as adults and 80 as juveniles, while there were 249 adults and 89 juvenile females. Using a sinusoidal equation, analysis of the GSI revealed a reproductive asynchrony between the genders, with males attaining their highest GSI values in January, while females peaked in March. For males, the sinusoidal regression for GSI values was significant only when used the complete data set (P=0.001), wears no trend was identified for bimonthly means (P=0.136). For females, by contrast, significant values were obtained for both the complete data set (P=0.012) and bimonthly GSI means (P=0.026). For the condition factor, the sinusoidal equation returned significant seasonal variation in both raw data (P=0.02) and with mean values (P=0.00) for males, but only with raw data for females (P=0.04), which appears to reflect variation in the energy budget between genders. With regard to the sex ratio, more reproductive females were captured than males in January and March, 2009, which suggests a pattern of segregation related to the reproductive process. These parameters are fundamental to the assessment, protection, and management of natural fish stocks, as well as providing guidelines for the development of conservation strategies.

scholarly journals Population structure and condition factor of Pseudotothyris obtusa (hypoptopomatinae) from three coastal streams in southern Brazil

1999 ◽  
Vol 42 (4) ◽  
Author(s):  
Denise de Freitas Takeuti ◽  
José Roberto Verani ◽  
José Marcelo Rocha Aranha ◽  
Márcia Santos de Menezes
Keyword(s):  
Young Adults ◽  
Population Structure ◽  
Sex Ratio ◽  
Condition Factor ◽  
Stream Fishes ◽  
Southern Brazil ◽  
Size Classes ◽  
Relative Condition Factor ◽  
Coastal Streams ◽  
Electric Fishing

Population structure features and condition factor of Pseudotothyris obtusa were compared between three coastal streams in southern Brazil. Fishes were monthly collected through electric fishing and measured in the total length. Fifteen fishes from each stream were dissected to identify their sex. The structure in size, sex ratio and young/adults ratio of populations were analysed and the length-weight relationship was obtained. The condition factor (K1) and the relative condition factor (Kn) were calculated for each stream. Fishes were grouped in 11 lenght classes of 3mm. The intermediate and bigger size classes were preponderant in the "Mergulhão" and "Colônia Pereira" streams, and the smaller and intermediate ones in the "Ribeirão" stream. Females prevailed in bigger size classes, reached bigger lengths than males, and were preponderant in all streams. The condition factors (K1 and Kn) were different in all streams, indicating better condition and higher weight values in fishes from the "Mergulhão" and "Colônia Pereira" streams.

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