Reproductive aspects of Galaxias platei (Pisces, Galaxiidae) in a deep lake in North Patagonia

2018 ◽  
Vol 69 (9) ◽  
pp. 1379 ◽  
Author(s):  
Daniela Milano ◽  
Juan P. Barriga
Keyword(s):  
Sexual Maturity ◽  
Gonadosomatic Index ◽  
Mature Oocyte ◽  
Native Fish ◽  
Oocyte Diameter ◽  
South American ◽  
Deep Lake ◽  
North Patagonia ◽  
Maximum Body ◽  
Maximum Body Size

Reproductive characteristics of the native fish Galaxias platei were studied in Lake Moreno, an ultra-oligotrophic deep lake in North Patagonia. According to histological analysis of ovaries, G. platei presents synchronous oocyte development typical of a group-synchronous spawner. Mature oocyte diameter ranged from 1031 to 1419μm. Based on the gonadosomatic index, annual spawning occurs between April and June (austral autumn) and is directly related to the water temperature of deeper strata (below 30m) where this species lives, but not with photoperiod. Female G. platei acquire sexual maturity at a length of 105mm, whereas males acquire sexual maturity at a length of 177mm. Delaying maturity to obtain higher fecundity, as well as maximum body size and longevity, indicates that G. platei is more specialised than the other South American Galaxias, G. maculatus, in terms of lifestyle. These specialised features are related to the stable environment G. platei lives in and indicate that it could eventually become a vulnerable species in unstable environments, such as the Patagonian lakes dominated by salmonids.

scholarly journals Reproductive biology of a tetragonopterinae (osteichthyes, characidae) of the Ubatiba fluvial system, Maricá - RJ

1999 ◽  
Vol 42 (4) ◽  
Author(s):  
Rosana Mazzoni ◽  
Jaqueline Petito
Keyword(s):  
Sexual Dimorphism ◽  
Reproductive Biology ◽  
Sexual Maturity ◽  
Gonadosomatic Index ◽  
Oocyte Diameter ◽  
Fluvial System ◽  
Development Stages ◽  
Maturation Stages ◽  
Mean Size ◽  
Reproduction Period

Aspects of the reproductive biology of one Tetragonopterinae was assessed in the Ubatiba river - Maricá / RJ. Length structure and mean size suggested sexual dimorphism, females reaching larger sizes than males. The onset of sexual maturity occured at 2.8cm for both the sexes. Fecundity, determined on ripe ovaries, showed positive correlation to females size and weight and varied from 595 to 5520 for 3.9cm and 6.2cm lengths respectively. The spawning type, defined as total, was determined by the oocyte diameter frequency from ovaries in different development stages. The frequency distribution of ovarian/testis maturation stages, associated with the temporal variation of the gonadosomatic index, suggested that the reproduction period was prolonged along the whole annual cycle.

Reproductive biology of the icefish Champsocephalus esox (Günther, 1861) (Channichthyidae)

1999 ◽  
Vol 11 (2) ◽  
pp. 140-149 ◽  
Author(s):  
Jorge Calvo ◽  
Elba Morriconi ◽  
Gustavo A. Rae
Keyword(s):  
Gonadosomatic Index ◽  
Dry Weight ◽  
Mature Oocyte ◽  
Hepatosomatic Index ◽  
Maturation Stage ◽  
Oocyte Diameter ◽  
Relative Fecundity ◽  
Similar Range ◽  
Males And Females ◽  
Sexually Mature

Champsocephalus esox is the only icefish species found outside Antarctica. In a population from the Beagle Channel, the complete annual reproductive cycle has been determined. Gonad maturity stages have been established for males and females by histological analysis. Males are sexually mature from January–September with a maximum gonadosomatic index (GSI) of 3.63%. Histologically, testes are very homogeneous and the degree of maturation of the testicular cysts is similar among different tubules at the same maturation stage. Running ripe testes have mature sperm and a few spermatogoniae arranged near the blind end of the tubules. In sexually active females that are found from February–November, ovaries contain only ripe oocytes or postovulatory follicles, together with a batch of previtellogenic oocytes. During hydration, oocyte diameter reaches 2.7 mm, and oocyte dry weight increases due to material intake, the maximum GSI in ovulated ovaries is 21.89 and hepatosomatic index (HSI) decreases. These facts suggest a transfer of matter from liver to the gonads. Absolute fecundity ranges from 3303–8600 oocytes. Relative fecundity ranges from 22.5–43.5 oocytes per gram total weight. In C. esox, relative fecundity has a similar range to those quoted for the different C. gunnari populations, whilst mature oocyte diameter is small and reproductive season extended compared to the same parameters in other Channichthyidae.

scholarly journals Reproduction of Carangoides vinctus (Perciformes: Carangidae) in the Mexican Central Pacific

2017 ◽  
Vol 44 (3) ◽  
pp. 610-622
Author(s):  
Gabriela Lucano-Ramírez ◽  
Estrella G. Rivera-Rios ◽  
Salvador Ruiz-Ramírez ◽  
Gaspar González-Sansón ◽  
Alejandro Perez-Toledo
Keyword(s):  
Sexual Maturity ◽  
Gonadosomatic Index ◽  
Reproductive Period ◽  
Oocyte Diameter ◽  
Central Pacific ◽  
Gonadal Maturity ◽  
Three Stages ◽  
Development Phases ◽  
Post Spawning ◽  
Average Catch

This study aims to determine some aspects of the reproduction of Carangoides vinctus, a species caught by the artisanal fishery on the south coast of Jalisco. The captures were made monthly with gillnets from January 1998 to December 2008. The organisms had total length of 17.0 to 41.2 cm, with females averaging 30.1 cm and 30.5 cm males. The sex ratio was 1.0: 1.1 males per females, which is not significantly different from the expected 1:1. A gonadal maturity scale of four stages for both sexes (immature, developing, spawning capable and post-spawning or spent) was used. In the first three stages of the ovary’s development, a septum dividing each lobe was present. In the analysis of oogenesis, seven oocyte development phases were identified and the oocytes developed asynchronously within the ovary. Based on the microscopic characteristics observed in the testis, it showed a lobular type development. The maximum values of the gonadosomatic index, the percentage of mature gonads and the oocyte diameter suggest that C. vinctus has a reproductive period from March to May. The length at sexual maturity (L50) was estimated at 26.04 and 23.77 cm for females and males, respectively; these sizes are lower than the average catch size in both sexes, suggesting that organisms are caught commercially when they have reached sexual maturity.

scholarly journals Ecología trófica y reproductiva de Hemibrycon sierraensis (Characiformes: Characidae) pez endémico del río Gaira, Sierra Nevada de Santa Marta, Colombia

2017 ◽  
Vol 65 (3) ◽  
pp. 1033
Author(s):  
Eduardo J. Ibarra-Trujillo ◽  
Carlos A. García-Alzate
Keyword(s):  
Sierra Nevada ◽  
Sexual Maturity ◽  
Condition Factor ◽  
Feeding Habits ◽  
Gonadosomatic Index ◽  
Stomach Contents ◽  
Trophic Niche ◽  
Oocyte Diameter ◽  
Frequency Of Occurrence ◽  
Average Size

The study of feeding habits in fishes can give important information about their role in the fish community, their functional role in the ecosystem, and their relationships with all available resources. We studied H. sierraensis from Gaira River and performed eight bi-monthly samples between May 2014 and November 2015. We analyzed fish stomach contents by the numerical (% N), volume (% V) and frequency of occurrence (% FO) methods; we also calculated the index of food importance (IA), coefficient of emptiness (CV), trophic niche breadth (used H ') and condition factor (K). Additionally, we determined the sex ratio, gonadosomatic index (RGS), fecundity, minimum and average size at sexual maturity, and oocyte diameter by standard methods. The Gaira River has irregular meanders with clear waters, and high current velocity through its drainage; it is generally oligotrophic, with a tendency to eutrophic condition in some places. Observed dissolved oxygen values were high (5.4 mg/L), electrical conductivity was 68.63 µS/cm, and pH was found neutral. We analyzed stomach contents of 477 specimens, and found a 1.59 % coefficient of vacuity. The species was found euryphagic in its feeding habits (H'= 0.69), omnivorous tending to insectivorous; its diet consisted mainly of Trichoptera larvae (Atanatolica sp.), followed in importance by snails (Gastropoda Pomacea sp.) and dipteran larvae such as Simulium sp. Significant differences in both frequency of occurrence and the volume consumed were observed for the different size classes, as well as between different seasons of the year. The condition factor indicated that the species was well fed. Sex was determined for 424 fish, of which 241 were male and 181 female, given a ratio of 1.3: 1 (male-female) which resulted significantly different (Chi 2: 16.14; P= 0.02). The gonadosomatic index indicated that reproduction occurs during the high water river phase, fecundity was high, and oocyte diameter was relatively small. Males reached sexual maturity at an average size of 67.08 mm SL, and females at 70.68 mm SL. Their life history strategy is seasonal r. Management and conservation plans for this species are required due to human intervention in their habitat, originated by the growing tourist activity in the area.

The controlling factors limiting maximum body size of insects

Lethaia ◽  
2008 ◽  
Vol 41 (4) ◽  
pp. 423-430 ◽  
Author(s):  
RYOKO OKAJIMA
Keyword(s):  
Body Size ◽  
Controlling Factors ◽  
Maximum Body ◽  
Maximum Body Size

scholarly journals Redescription of Ochmacanthus batrachostoma (Miranda-Ribeiro, 1912) (Siluriformes: Trichomycteridae): a possible case of incipient paedomorphism

2016 ◽  
Vol 14 (1) ◽  
Author(s):  
Caio S. Neto ◽  
Mário de Pinna
Keyword(s):  
Body Size ◽  
Internal Anatomy ◽  
Morphometric Traits ◽  
Type Specimens ◽  
Caudal Peduncle ◽  
Caudal Fin ◽  
Maximum Body ◽  
Maximum Body Size

ABSTRACT The lepidophagous stegophiline catfish Ochmacanthus batrachostoma (Miranda-Ribeiro, 1912) is endemic to the Paraná-Paraguai basin and is the only member of its genus in that drainage. It remains a poorly-known taxon mainly due to the historical scarcity of study specimens. The species is herein redescribed on the basis of type and non-type specimens from Brazil, Argentina and Paraguay. Ochmacanthus batrachostoma can be distinguished from congeners by the presence of long maxillary and rictal barbels, reduction of the posterior end of the caudal peduncle, a tadpole-like caudal fin and peduncle, among other morphometric traits and features of internal anatomy. Comparisons show that a number of unique traits of adult O. batrachostoma resemble conditions seen in juvenile specimens of other members of Stegophilinae. Such traits are also more pronounced in juveniles of O. batrachostoma itself. The species also has the smallest maximum body size in Ochmacanthus and among the smallest of any stegophiline. In combination, such observations suggest that the species is paedomorphic, although to a degree less extreme than seen in some other trichomycterids. This is the first possible case of paedomorphosis identified for stegophilines.

Reproductive cycle of the Manila clam (Ruditapes philippinarum): an intensively harvested invasive species in the Tagus Estuary (Portugal)

2017 ◽  
Vol 98 (7) ◽  
pp. 1645-1657 ◽  
Author(s):  
Paula Moura ◽  
Paulo Vasconcelos ◽  
Fábio Pereira ◽  
Paula Chainho ◽  
José Lino Costa ◽  
...  
Keyword(s):  
Invasive Species ◽  
Reproductive Cycle ◽  
Sexual Maturity ◽  
Ruditapes Philippinarum ◽  
Manila Clam ◽  
Tagus Estuary ◽  
Gonad Maturation ◽  
Oocyte Diameter ◽  
Ruditapes Decussatus ◽  
Spawning Period

The present study aimed to describe the reproductive cycle and estimate the size at sexual maturity of the Manila clam (Ruditapes philippinarum) in the Tagus Estuary (Portugal). Specimens were collected monthly from September 2013 to December 2015 during fishing surveys using bivalve dredges. The gametogenic cycle was described in detail using gonad histology and monitored throughout the study period by the monthly variation in the frequency of gonad maturation stages, mean gonadal index and mean oocyte diameter. This invasive population of R. philippinarum displayed synchronous gonadal development between sexes, with ripening occurring mainly in April and May followed by an extensive spawning period until November–December. Individuals reached the size at first sexual maturity at 29.4 mm in shell length (i.e. before 1 year old). Furthermore, the reproductive strategy, dynamics and potential were compared between the invasive R. philippinarum and the native congeneric carpet shell clam (Ruditapes decussatus). Overall, the data gathered in this study constitutes valuable baseline information to propose conservation strategies and implement management measures to minimize the harmful impacts caused by this invasive species on local ecosystems and native biodiversity, particularly over populations of autochthonous bivalves.

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.

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