scholarly journals Density, Sex Ratio, Size, Weight, and Recruitment of <i>Plicopurpura pansa</i> (Gastropoda: Muricidae) in Costa Chica, Guerrero, México

2012 ◽  
Vol 02 (04) ◽  
pp. 157-166 ◽  
Author(s):  
Rafael Flores-Garza ◽  
Arcadio Valdés González ◽  
Pedro Flores-Rodríguez ◽  
Sergio García-Ibáñez ◽  
Norma L. Cruz-Ramirez
Keyword(s):  
Sex Ratio ◽  
Costa Chica ◽  
Ratio Size

scholarly journals Blue whiting (Micromesistius poutassou) sex ratio, size distribution and condition patterns off Portugal

2017 ◽  
Vol 30 ◽  
pp. 24 ◽  
Author(s):  
Patrícia Gonçalves ◽  
António Ávila de Melo ◽  
Alberto G. Murta ◽  
Henrique N. Cabral
Keyword(s):  
Sex Ratio ◽  
Size Distribution ◽  
Blue Whiting ◽  
Ratio Size

Sex ratio, size distribution and nitrogen resorption in the dioecious tree species Bursera morelensis (Burseraceae)

2008 ◽  
Vol 24 (4) ◽  
pp. 463-466 ◽  
Author(s):  
Numa P. Pavón ◽  
Irving de Luna Ramírez
Keyword(s):  
Sex Ratio ◽  
Plant Architecture ◽  
Significant Proportion ◽  
Reproductive Cost ◽  
Plastic Response ◽  
Compensatory Mechanisms ◽  
Plant Populations ◽  
Nitrogen Resorption ◽  
Stressful Environment ◽  
Ratio Size

Dioecious plant populations have generally been considered to maintain sex ratios of 1:1 (Allen & Antos 1993, Carroll & Mulcahy 1993, Charnov 1982). The sex ratio does, however, change if the plants are growing in a stressful environment, often being male-biased under these conditions (Ortiz et al. 1998, 2002). This pattern has been explained by differences in how the sexes resolve their respective energy requirements (Obeso et al. 1998). Females generally assign more resources to reproduction in comparison to growth and maintenance than do males, and they are smaller and longer-lived (Allen & Antos 1993, Nicotra 1999, Obeso et al. 1998, Willson 1983). Thus their higher reproductive costs take a toll on females, modifying the population sex ratio in favour of males (Allen & Antos 1993, Lovett-Doust & Lovett-Doust 1988). However, in order to determine the reproductive cost it is necessary to consider the compensatory mechanisms (Obeso 2002). These reduce the reproductive cost and include plastic response in terms of plant architecture and plant physiology. For example, nutrient resorption is a process that may help decrease dependence on nutrient intake, thereby constituting an important nutrient economy mechanism that can also reduce the reproductive cost if a significant proportion of the nutrients had been reassigned to reproduction (Killingbeck 1986, Obeso 2002).

scholarly journals Reproductive biology of the orange mud crab Scylla olivacea (Herbst, 1796) from the Pichavaram mangroves of south-east India

2019 ◽  
Vol 66 (1) ◽  
Author(s):  
C. Viswanathan ◽  
M. Pravinkumar ◽  
T.V. Suresh ◽  
V. Elumalai ◽  
S.M. Raffi
Keyword(s):  
Sex Ratio ◽  
Size Distribution ◽  
Reproductive Biology ◽  
Sexual Maturity ◽  
Carapace Width ◽  
Distribution Analysis ◽  
Mud Crab ◽  
Indian Coast ◽  
Ratio Size ◽  
Commercially Important

The present study was conducted to assess the size distribution, sex ratio, size at first sexual maturity, fecundity and spawning season of the commercially important orange mud crab Scylla olivacea (Herbst, 1796) in Pichavaram mangroves in south-east India. This study is the first contribution to the knowledge of reproductive biology of S. olivacea from the Indian coast. Size distribution analysis in the fishery revealed the irrational exploitation of undersized S. olivacea. The estimated sex ratio deviated from equality, being 1:0.87, revealing a male domination. Size at first sexual maturity was determined to be 87 mm in carapace width (CW) in females. Fecundity ranged from 1.16 to 3.53 million in females of 76 to 135 mm CW. Breeding takes place year-round with a peak in pre-monsoon, indicating that it is a prolific breeder. Results revealed that immature individuals of S. olivacea contributed significantly to the catches and thus an effective management of the resource by framing minimum legal size is crucial so that the females are allowed to spawn at least once prior to capture.

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.

scholarly journals Sex Ratio And Size At First Maturity Of Blue Swimming Crab (Portunus pelagicus) Salemo Island Pangkep Regency

2016 ◽  
Vol 21 (1) ◽  
pp. 17 ◽  
Author(s):  
Muh. Saleh Nurdin ◽  
Syamsu Alam Ali ◽  
Dewi Yanuarita Satari
Keyword(s):  
Sex Ratio ◽  
Coral Reefs ◽  
Swimming Crab ◽  
High Demand ◽  
Chi Square ◽  
Portunus Pelagicus ◽  
Ratio Size ◽  
Chi Square Test ◽  
First Maturity ◽  
Size At First Maturity

Blue swimming crab (Portunuspelagicus) is aeconomical valuable fisheries importantcommodity  due to the high demand and availability jobs created for the fishermen. Due to their high demand blue swimming crab heavily exploited from Salemo Island. This study aimed at comparing the sex ratio and the size at first maturity of blue swimming crab caught in mangrove ecosystems, coral reefs, and seagrass. Sex ratio was analyzed using chi square test and the size at first maturity was analyzed using the Spearman-Karber formula. The results showed the sex ratio ofmales and femalessmall crab caught in every ecosystem is balanced. The size at first maturity of blue swimming crab caught in mangrove, seagrass and coral reefs, each to the male 81,08 mm, 102,36 mm and 102,87 mm in width and size of female 94,54 mm, 83,35 mm, 98,31 mm width. In a reference to government regulations, the blue male swimming crab caught in the coral reef and seagrass ecosystems have yet to size at first maturity is allowed to be captured. Keywords: blue swimming crab, sex ratio,size at first maturity, Salemo Island

Diel Pelagic Foraging by a Pandalid Shrimp (Pandalus montagui) off Resolution Island (Eastern Hudson Strait)

1992 ◽  
Vol 49 (3) ◽  
pp. 565-576 ◽  
Author(s):  
C. Hudon ◽  
D. G. Parsons ◽  
R. Crawford
Keyword(s):  
Sex Ratio ◽  
Vertical Distribution ◽  
Feeding Activity ◽  
Bottom Trawl ◽  
Staple Food ◽  
Benthic Organisms ◽  
Size Frequency Distribution ◽  
Ratio Size ◽  
Plankton Sampler ◽  
The Vertical Distribution

The vertical distribution and diet of shrimp (Pandalus montagui) were investigated using a multistage plankton sampler (BIONESS) and were compared with those of shrimp captured on the bottom using a trawl. Massive nocturnal vertical migrations of shrimp were observed in association with intense pelagic feeding activity. The sex ratio, size frequency distribution, and diet of shrimp caught in the water column differed markedly from shrimp caught during their stay on the bottom. Pelagic migrants were mostly males (75%), extending their planktonic foray into morning hours, whereas ovigerous (12%) and nonovigerous (13%) females returned to the bottom at dawn. In the trawl, the representation of males (43%) and ovigerous females (45%) differed, but also fluctuated on a diel cycle. Stomachs of shrimp captured in the BIONESS were fuller and the contents were in better condition than found in shrimps captured in the bottom trawl. Pelagic shrimp fed opportunistically on a variety of zooplankters, using copepods as a staple food. Stomachs of shrimp from the bottom trawl contained chitinous debris, sand grains, and small amounts of benthic organisms. The occurrence of daily vertical feeding migrations results in the unavailability of a variable proportion of the total shrimp biomass to bottom trawls.

scholarly journals Estrutura populacional de Callinectes danae (Decapoda, Portunidae) da Lagoa da Conceição, Florianópolis, SC, Brasil

1992 ◽  
Vol 21 ◽  
Author(s):  
José Olinto Branco ◽  
Setuko Masunari
Keyword(s):  
Body Weight ◽  
Sex Ratio ◽  
Carapace Width ◽  
The Body ◽  
Migration Route ◽  
Humid Climate ◽  
Ratio Size ◽  
Il Y A ◽  
The Mean ◽  
Callinectes Danae

Os seguintes aspectos foram tratados sobre a estrutura populacional do siri azul Callinectes danae da Lagoa da Conceição, SC e área costeira (27°30’30”- 27°37’l5” S e 48°00’00”-48°31'0”W: proporção de sexos, composição de tamanho, flutuação da abundância, distribuição espacial e relação peso/largura da carapaça. Coletas noturnas mensais de janeiro/8S a julho/89 em 10 pontos de coleta resultaram na captura de 613 machos e 511 fêmeas, dos quais foram obtidos dados morfométricos e peso do corpo. A temperatura da água de superfïcie variou de 12,3°C (junho) a 27,8°C (janeiro) e a salinidade média de 26,0 °/oo (fevereiro) a 35,5 °/oo (março), valores típicos de estuários de clima mesotérmico úmido. Os juvenis com 68,15 % predominaram sobre os adultos com 31,85 % . Com exceção de quatro meses, a proporção de sexos foi de 1:1 no decorrer do estudo. A amplitude de variação da largura da carapaça foi de 1,5 a 13,5 cm entre os machos e de 2,0 a 11, cm entre as fêmeas, Maior número de classes de largura da carapaça e maior abundância da população foram observados no subsistema Central, seguido do Sul e Norte; uma relação direta com a proximidade do mar. A forte predominância de fêmeas ovígeras na área costeira indica-a como rota de migração daquelas para o mar, Houve dois picos de abundância no período (fevereiro e setembro) representados pela maior porcentagem de juvenis. A expressão da relação entre o peso do corpo e a largura da carapaça foi de wl= 0,0715, wid 2,91 para machos e wt= 0,0739 . wid 2,8994 para fêmeas, valores próximos aos de C. danae do Rio Itiberê na Baía de Paranaguá. Abstract The following aspects of population strulucture were carried out about Callinectes danae of Conceição Lagoon and seashore area, SC (27°30’30”-27°37'15" S and 48°00’00”-48°30'0"W): sex ratio, size, oviposition, fluctuation of abundance, spacial distribution and body weight/carapace width relationship. A total of 613 males and 511 females were caught at night, monthly, from January 1988 to July 1989 at 10 collection sites. Meristic date and body weíght of all crabs were obtained. The surface water temperature oscillated between 12.3°C (June) to 27.8°C (January) and the mean salinity ranged from 26.0 °/oo (February) to 35.5 °/oo (March), which are typical values for estuaries with mesothermic-humid climate. The juveniles (68.15 %) predominated over adults (31,85 %). The sex ratio was 1:1, except in four months. The width variation of the carapace ranged from 1.5 to 13.5 cm in the males and 2.0 to 11.5 cm in the females. Higher number of carapace width classes and higher populalion abundance were observed in the Central subsystem, followed by South and North: a direct relationship with the sea nearness. The strong predominance of ovigerous females in the seashore area indicates it as migration route of those crabs to the sea. There were two abundance peaks in the study period (February and Septetuber) due lo higher percentage of juveniles. The body weight/carapace width relationship was wt 0.0715, wid 2.9153 to males and wl = 0.0739 . wid 2.8994 to females, values which were near to C.danae of the ltiberê River, Paranaguá Bay. Résumé Les suivants sujets ont été abordés sur la structure de la population de crabes bleus Callinectes danae de la Lagoa da Conceição. SC, et surface côtière (27°30’30”-27°37’15” S et 48°0'0"- 48°30’0” W): proportion de sexes, composilion de tailie, fluctuation d’abondance, distribution spatiale et relation poid/largeur de carapace. À d’échantillonages nocturnes mensuels entre juin de 1988 et juillet de 1989 en dix différent points, ont été capturés 613 mâles et 511 femelles, desqueles on a obtenu des données morphométriques et poid du corps. La temperature de l’eau superficielle a eu une variation entre 12,3°C (juin) et 27,8°C (janvier), et la salinité rnoyenne entre 26,0 °/oo (février) et 35,5 °/oo (mars), qui sont des valeurs typiques d’ástuaires de climat mésothermique humide. Les jeunes ont prédoniiné sur les adultes avec 68,15 % contre 31,85 %, A l’exception de quatre mois, la proportion de sexes a été de 1:1 pendant le développement de cet étude. L’amplitude de variation de largeur de carapace a été de 1,5 à 13,5 cm entre les mâles et de 2,0 à 11,5 cm entre les femelles. Le plus grand nombre de classes de largeur de la carapace et la plus grande abondance de la population on été observés dans le subsystème Central, en se suivant le Sud et le Nord respectivement; une relation directe avec la proximté de la mer. Il y a eu deux pics d’abondance pendant la période d’études (février et septembre) représentés par le plus grand pourcentage de jeunes. L’expression de la relation entre le poid du corps et la largeur de la carapace a été de wt=0,0715 , wid 2,9153 pour les mâles ei wt 0,0739. wid 2,8994 pour les femelles, valeurs proches à celles de Callinectes danae du fleuve Itiberê la baie de Paranaguá.

scholarly journals Biological Aspects of Squids (loligo sp.) Caught by Fishermen in Manokwari Waters

2019 ◽  
pp. 65
Author(s):  
Amida E Ayorbaba ◽  
Nurhani Widiastuti ◽  
Arnoldus S. Ananta ◽  
Paulus Boli
Keyword(s):  
Weight Gain ◽  
Sex Ratio ◽  
Size Distribution ◽  
Growth Pattern ◽  
Female Sex ◽  
Ratio Size ◽  
Length Increase ◽  
Landing Sites ◽  
Biological Aspects ◽  
Relationship Of

Squid (Loligo sp.) is one of the fisheries commodities caught in Manokwari waters. The aim of this study was to determine the biological aspects of Loligo sp. including the sex ratio, size distribution, growth pattern, and the lengthy relationship of Loligo sp. from Manokwari waters. This research was conducted in January until March 2017, in three landing sites of squid (Loligo sp) namely Fanindi Pantai, Borobudur and Arowi village. The method used is observation technique in the laboratory includes measurements of length and weight to find out the size distribution and growth pattern of captured Loligo sp. and surgery to determine the sex ratio. The male-female sex ratio of Loligo sp. was 1.3: 1.0 with a range of coat length and wight dominated by male. The growth pattern of Loligo sp in Manokwari waters is negative allometric, where the length increase is faster than the weight gain.

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