Variation In Gonadosomatic Index Research Articles

Sexual dimorphism and reproductive biology of Cephalocassis borneensis (Siluriformes: Ariidae), a paternal mouth-brooding fish in the Mekong River.

Information on the reproductive biology of fish species is essential for fisheries management, conservation and culture potential assessment. Therefore, this study aimed to understand the sex-based morphological differences and reproductive characteristics of Cephalocassis borneensis, an ariid species with a rapid decline of wild populations. Fish samples were collected monthly from local fishermen (n = 1092) in the Vietnamese Mekong River over a year. Morphological analyses revealed that sexual dimorphism was observed in mature, but not immature, fish. The length at first maturity (Lm ) was smaller for males (11.5 cm) than for females (12.5 cm). Mature males had larger head length and pre-pectoral distance than mature females, increasing the space for oral incubation of fertilized eggs and larvae in males. Conversely, females were larger in three head parameters (head angle, head width and head depth) and three abdomen parameters (body deep, ventral fin length and distance between pectoral and ventral fin) involved in ovary development. Paternal mouth-brooding behaviour is an important reproductive strategy in C. borneensis to increase offspring survival. Monthly variations in gonado-somatic index and condition factor (K) and the presence of maturation stages indicated that C. borneensis spawns year-round, mainly in the rainy season from June to October. This species' fecundity was relatively low, from 10 to 31 eggs per female of quite large sizes (about 7.30 ± 0.68 mm in diameter). Besides, non-functional oocytes (hyaline eggs) of smaller size (<3 mm) were found in the females' ovaries. Low fecundity with large eggs and paternal care indicated that the species is an equilibrium strategist. These characteristics are critical in developing ariid species conservation plans, such as setting the time and mesh-size for fishing, and domestication programmes in artificial conditions.

Seasonal variations in gonadosomatic index and seminal quality of squirrel monkeys (Saimiri collinsi).

We hypothesized that seasonal variations in testicular biometry in Saimiri collinsi are influenced by body mass and that testicular enlargement is related to improved seminal quality. Therefore, the gonadosomatic index (GSI) can be a tool to determine reproductive seasons and the predictors of seminal quality. Body mass, testicular biometry, and semen samples were obtained from eight adult males monthly and evaluated. In the non-fattening/non-reproductive season, the body mass and GSI decreased and increased, respectively, in the fattening. A positive correlation was only observed between the GSI and seminal volume. During fattening, high seminal volume and normal morphology were observed, but sperm concentrations were low. The GSI cannot be used as a predictor of seminal quality, but selective pressure to improve seminal quality may increase the chances of fertilization at fattening. The GSI provides new information on seasonality and can be used to identify reproductive seasons in squirrel monkeys.

Variations in Gonadosomatic Index, Gonadal Development and Spawning Induction of Spotted Scat Scatophagus argus (Linnaeus, 1766)

This study evaluated variations in gonadosomatic index (GSI), gonadal development stages, and hormonal spawning induction of Scatophagus argus in captivity. Male and female fish were cultured separately in net cages in Tam Giang lagoon, Central Vietnam, from January to December 2020. Five fish of each sex were randomly sampled monthly. Gonads were collected, GSI determined, and subsequently prepared for histology. Gamete quality was assessed with a light microscope. Spawning was hormonally induced with different doses of human chorionic gonadotropin (hCG) and luteinizing hormone-release hormone (LHRH-A2). Gonadal development started to increase in March, peaking in July. The peak spawning period of the fish was from June to August, displaying the highest GSI value, sperm motility, and oocyte diameter. Only female GSI fluctuated significantly month-by-month (P&lt;0.05). Histological examination indicated that S. argus is a multiple-spawner. Application of LHRH-A2 (70 µg/kg) stimulated spawning and resulted in better latency periods, fertilization, and hatching rates.

CHANGES IN PLASMA LEVELS OF STEROID HORMONES DURING SEXUAL MATURATION OF MALE HELICOPTER CATFISH (WALLAGO ATTU) IN CAPTIVITY

In order to provide reliable indicators of the spawning season of captive helicopter catfish (Wallago attu), this study evaluated the temporal variation in gonadosomatic index (GSI), plasma levels of testosterone (T), and 11-ketotestosterone (11-KT) in male broodstock in captivity. GSI was estimated as the percentage of the relative weight of testis to total body weight. Plasma levels of sex steroids were determined by enzyme-linked immunosorbent assay (EIA). Testis samples were dehydrated and embedded in paraffin, then sectioned at 5 μm thickness. The highest level of T (402.1 ± 16.7 pg/mL) was found in June, followed by a peak in 11-KT level (76.9 ± 4.7 pg/mL) in May. Testes containing the highest concentrations of spermatozoa were observed from June to August. The GSI of males increased significantly from January to June and peaked in July (2.14%). Taken together, we conclude that the spawning season of captive helicopter catfish occurs from June to August. These results will contribute to the basic knowledge of the reproductive biology of helicopter catfish, which can be useful in artificial breeding.

Ejaculate characteristics over seasons in five species of lancehead pitvipers (Bothrops spp) kept in captivity.

Due to their major medical importance in Latin America, lancehead pitvipers are frequently kept and bred in captivity for venom extraction to the production of antivenom serums. Nevertheless, despite the great contribution given to captive breeding, much of the knowledge of Bothrops' reproductive biology derived from sporadic and insufficient data provided by zoological collections. Thus, we aimed to investigate seasonal changes in gonadosomatic index (GSI) and seminal parameters (e.g., volume, concentration, motility, viability, and acrosome integrity) of five species of lancehead pitvipers from different biomes and phylogenetic groups, maintained in the indoors serpentarium at Butantan Institute (Brazil). Patterns of variation in GSI and semen parameters differed from one species to another, suggesting that captive populations should perhaps be managed distinctly to maximize reproductive success. Furthermore, in none of the studied species did changes in GSI occur concomitantly with seminal variations. GSI remained unaltered year-round for Jararaca (Bothrops jararaca) and Brazilian lancehead (Bothrops moojeni), whereas it peaked in the autumn for Common lancehead (Bothrops atrox), Jararacussu (Bothrops jararacussu), and Whitetail lancehead (Bothrops leucurus). But surprisingly, the scenario was inverted when we estimated the total number of motile spermatozoa per season, as Jararaca and Brazilian lancehead displayed seasonal differences and the other species did not vary throughout the year. Potential ecological and evolutionary factors underlying these differences were also discussed in the present article. Together, these findings can help to better define breeding management strategies for each species in captivity, in addition to optimizing the future use of artificial insemination and semen cryopreservation.

Reproductive cycle of sea urchin Echinometra vanbrunti (Echinodermata: Echinoidea) from the Gulf of California

ABSTRACT Echinometra vanbrunti is an echinoid found in abundance in the eastern Pacific, including the Gulf of California in Mexico. The aim of this study is to document its annual reproductive cycle from monthly sampling. Growth, condition and gonadosomatic index (GSI) were determined from morphometric data. Additionally, sex ratio and morphology of sea urchin gonads and their gametes were analysed by histology and microscopy. The growth pattern of E. vanbrunti was allometric. The monthly variations of GSI are explained by gonad condition and the gametogenesis cycle. An annual reproductive cycle was observed with higher GSI from July–September and the highest percentage of females and males in the mature stage in the same period. Gonad histology agreed with this single gametogenic cycle per year, and gametogenesis in males and females being highly synchronized in this species. Spawning period started in July and ended in November for both sexes.

Gonadal development in a landlocked population of pejerrey fish Odontesthes argentinensis during spawning season in relation to sex steroids and water temperature

ABSTRACT The relationship between water temperature and gonadal maturation of a landlocked ecophenotype of marine pejerrey (Odontesthes argentinensis) in La Salada de Pedro Luro lake was analysed during three spawning seasons. Mainly vitellogenic females were found in August (winter), some ovulating in October (mid-spring) and with atretic oocytes in December (end of spring). In accordance with this, gonadosomatic index (GSI) and estradiol plasma levels showed maximum values in October (7.6 ± 0.7%; 1631.7 ± 256.1 pg/mL) and minimum values in December (1.2 ± 0.3%; 230,33 ± 8,74 pg/mL). Spermiating males were found during the whole spawning season and only arrested in December. The highest GSI values were recorded in October (4.6 ± 0.2%) and for testosterone (T) in August (1113.2 ± 503.8 pg/mL). Meanwhile, in December the minimum GSI and T plasma values (1.3 ± 0.6%, 323.8 ± 5.3 pg/mL) were observed. According to the Fourier fitted models, temperature explains more than 70% of the observed variation in GSI in both sexes. Moreover, the total GSI variation range was positively related to the total temperature range variation experienced during the reproductive seasons demonstrating the influence of this environmental variable on maturation intensity and dynamics.

Reproductive biology of Indian halibut, Psettodes erumei from the northern Persian Gulf and Oman Sea (Teleoststei: Psettodidae)

The reproductive biology of Indian halibut, Psettodes erumei , a commercially valuable flatfish species, in the northern Persian Gulf and Oman Sea was studied. A total of 433 specimens were collected monthly from October 2016 to November 2017, and their length, weight, sex, gonad and liver weight, and maturity status were recorded. Monthly variations in Gonado-somatic index showed two obvious peaks in the spawning period in both sexes. Observations from the seasonal maturation curve, the frequency distribution of the female gonadal development stages and the condition factor confirmed recent findings that the spawning periods have two peaks, a higher peak in April-May (spring) and a lower peak in October (autumn). The size at first maturity of females was estimated to be 38.20 cm in total length. The absolute fecundity ranged from 18072 to 332171 eggs while the relative fecundity ranged from 22 to 161 eggs/g. Absolute fecundity was positively correlated with body related parameters (total length/weight) and with gonad weight. Combined, the information provided in this study could be useful for resource managers to set seasonal closure during peak spawning periods and implement minimum size limits above the size at first maturity to let the fish spawn at least once before capture.

Reproductive characteristics of the blue swimming crab, Portunus pelagicus (Decapoda, Brachyura: Portunidae) from the Bitter Lakes, Suez Canal, Egypt

The reproductive characteristics of crabs play an important role in their fisheries management. The blue swimming crab Portunus pelagicus is one of the most commercially important crustaceans distributed along the Egyptian Coast; it has a great demand for their esteemed food. The spawning season of P. pelagicus was estimated based on three parameters: the monthly variation in both the maturity stages and in the gonado-somatic index (GSI) beside the histological examination of the ovarian structure. P. pelagicus was capable of continuous spawning throughout the year, where the mature stage was found to be distributed along the whole year indicating that crabs may be spawn at different times. P. pelagicus spawning mainly takes place twice, January-February (winter period) and June- August (summer period). As the monthly variation in GSI exhibit two distinct peaks in winter and summer. The mean size at which P. pelagicus became potentially reproductive (Lm50) was estimated to be 9.32 cm CW for males and 8.45 cm CW for females. To achieve the sustainable utilization, it is recommended to increase the minimum fishing size of this crab to at least 11.0 cm CW to protect the stock biomass and allow young individuals to reach the suitable marketable size.

Reproductive biology of common carp (Cyprinus carpio Linnaeus, 1758) in Lake Hayq, Ethiopia

This study was conducted in Lake Hayq between January and December 2018. The objectives of this study were to determine the growth, condition, sex ratio, fecundity, length at first sexual maturity (L50), and spawning seasons of common carp (Cyprinus carpio). Monthly fish samples of C. carpio were collected using gillnets of stretched mesh sizes of 4, 6, 7, 8, 10, and 13 cm and beach seines of mesh size of 6 cm. Immediately after the fish were captured, total length (TL) and total weight (TW) for each individual were measured in centimeters and grams, respectively, and their relationship was determined using power function. Length at first maturity (L50) was determined for both males and females using the logistic regression model. The spawning season was determined from the frequency of mature gonads and variation of gonadosomatic index (GSI) values of both males and females. Fecundity was analyzed from 67 mature female specimens. The length and weight relationship of C. carpio was TW = 0.015TL2.93 for females and TW = 0.018TL2.87 for males that indicate negative allometric growth in both cases. The mean Fulton condition factor (CF) was 1.23 ± 0.013 for females and 1.21 ± 0.011 for males. The value of CF in both cases was > 1 that shows both sexes are in good condition. Among the total 1055 C. carpio collected from Lake Hayq, 459 (43.5%) were females and 596 (56.5%) were males. The chi-square test showed that there was a significant deviation between male and female numbers from 1:1 ratio (χ2= 22, df = 11, P > 0.05) within sampling months. The length at first sexual maturity (L50) for females and males were 21.5 and 17.5 cm, respectively. Males mature at smaller sizes than females. The spawning season of C. carpio was extended from February to April, and the peak spawning season for both sexes was in April. The average absolute fecundity was 28,100 ± 17,462. C. carpio is currently the commercially important fish while Nile tilapia fishery has declined in Lake Hayq. Therefore, this baseline data on growth, condition, and reproductive biology of common carp will be essential to understand the status of the population of carp and design appropriate management systems for the fish stock of Lake Hayq, Ethiopia, and adjacent countries.

Age, growth and reproductive traits of invasive goby Taenioides cirratus in the Chaohu Lake, China

The eel goby Taenioides cirratus (Blyth, 1,860) is a small fish inhabits muddy bottoms of brackish-water in the Indo-West Pacific. It has invaded many inland freshwater lakes in China, such as the Chaohu Lake, Gaoyou Lake and Nansi Lake, and its population increased rapidly in these freshwater lakes in recent years. The age, growth and reproductive traits of T. cirratus invading the Chaohu Lake were studied. A total of 482 specimens (210 females, 204 males and 68 juveniles) with total length (TL) ranging from 9.4 to 20.6 cm were collected using the benthic fyke nets at monthly intervals from March 2018 to February 2019. The sagittal otolith was used for age determination. Monthly variation of marginal increment ratio indicated that the annual forming of opaque band on sagittal otolith was completed during March and April. For both sexes, only four (from 0+ to 3+ years) age groups were observed and 1+ and 2+ years age individuals dominated the population. Back calculated length at age showed males grew faster than females. Both sexes reached maturity at 1+ year age and the TL at first maturity (TL50) was 12.6 cm for females and 11.9 cm for males. Monthly variation of gonado-somatic index indicated that the spawning occurred from May to August. The fecundity ranged from 967 ova to 5,114 ova, with a mean of 3,205 ova. Our study provides a comprehensive data on the key life history traits of T. cirratus for the first time.

Reproductive biology of the mackerel scad Decapterus macarellus from Cabo Verde and the implications for its fishery management

The mackerel scad Decapterus macarellus is of great social and economic importance to Cabo Verde citizens; however, in recent years catches have shown an unexplained decline. The harvest is regulated by way of a minimum legal size and a seasonal closure, with both measures based on the results of reproductive studies that did not consider the microscopic characteristics of the gonads. This study aimed to analyse the gonads microscopically in order to classify the sexual development stage of individuals and to estimate the size at first maturity and the reproductive season. This information was then used to analyse the match between the reproductive parameters and the management measures. The samples comprised 284 females (20–36 cm fork length [FL]) and 85 males (21–35 cm FL). The annual variation in gonadosomatic index and the monthly frequencies of mature phases suggest that the reproductive season occurs from March to October, with two spawning peaks, one in March and another from July to October. The current seasonal closure (from July to September) covers the main reproductive period. However, the species has a long spawning period and the timing of peaks can vary between years; hence, a reassessment of this management measure is recommended. The sizes at first maturity were estimated at 24.1 cm FL for females, and 26.6 cm FL for males. These values are higher than the minimum legal size (20 cm FL) currently established for management of the species at Cabo Verde; thus, we strongly recommend an increase in the minimum legal size in an attempt to reduce catches of immature individuals.

Biological features of Chanda nama (Ambassidae) in the Old Brahmaputra River, Bangladesh

Biological features including sex ratio, length-frequency distributions (LFDs), size at sexual maturity, spawning season, length-weight relationships (LWRs) and condition factor of Chanda nama were studied in the Old Brahmaputra River, Bangladesh. There was no significant difference in sex ratio. LFDs indicated no significant differences in size between the sexes. Size at sexual maturity was estimated at ~3.0 cm standard length. Monthly variations in gonadosomatic index indicate that the main spawning season is from July to August. The LWRs showed isometric growth in males and positive allometric growth in females. Fulton’s condition factor varied in both sexes and was attributed to variations in GSI with maturity. The findings of this study will be helpful to formulate conservation and management strategies of C. nama population in the Old Brahmaputra River and surrounding ecosystems.

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

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 &lt; 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.

Reproductive Biology of Coral Catshark Atelomycterus marmoratus (Anonymous [Bennett], 1830) in Seribu Islands, Indonesia

This study provides information on the reproductive biology of the coral catshark caught in the waters around Seribu Islands, Indonesia. A total of 257 coral catsharks were collected from February 2017 to January 2018. The total length of coral catshark ranged from 170 to 585 mm for females and 255-575 mm for males, respectively. The total weight of females ranged from 85 to 640 g and males from 100 to 620 g The sex ratio between females and males was 0.45 and it was not significantly different from the expected 1:1 ratio. The growth pattern of coral catsharks in Seribu Island was negatively allometric and the population was dominated by mature sharks. The mean size at first maturity was estimated to be 557 mm for females and 514 mm for males, based on to the relationship between the proportion between maturity stage and total length. The ovulation season was estimated occur from October to March, whereas September to April was mating season based on monthly variations of gonadosomatic index (GSI) values and the occurrence of egg cases in uterus.

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

This work provides for the first time a description of the reproductive biology ofTrachurus picturatusin 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 &gt; 0.9) and isometric growth (b = 3) for both sexes. Results indicate that the spawning season ofT. picturatusstarts 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 ofApocryptes bato(Gobiidae) in the Payra River, southern Bangladesh

The gobioid fish Apocryptes bato (Hamilton, 1822) is a species of mudskipper found in Bangladesh, India, and Myanmar. The reproductive biology of A. bato including sex ratio, size at sexual maturity, breeding season, fecundity, and condition factor was studied in the Payra River, southern Bangladesh during May 2016 to April 2017. A total of 1,028 specimens (303 males and 725 females) were collected. The overall sex ratio was significantly different from the expected value of 1:1 (male: female = 1:2.39, χ2 = 173.23, p < 0.05). Size at sexual maturity was estimated as 4.9 cm standard length. Monthly variations in gonadosomatic index indicate that the main breeding season is from May to December. There was a significant positive correlation of body length and body weight with fecundity. Fulton's condition factor varied in both sexes and was attributed to variations in GSI with maturity. Breeding season was significantly associated with rainfall, but not air temperature. Our findings should improve management and conservation of this fish in the Payra River and surrounding ecosystems.

Reproductive biology and size structure of Lethrinops gossei (Teleostei:Cichlidae) in the demersal trawl fishery of the southeast arm of Lake Malaŵi, Malaŵi

The reproductive biology and size structure was determined for Lethrinops gossei, one of the most abundant fish species contributing 26% of the catch in the demersal trawl fishery of the Southeast Arm of Lake Malaŵi. Breeding seasonality was analyzed on the basis of monthly variation of gonado-somatic index and gonadal appearance, while sexual maturity was determined by fitting the logistic model to the proportions of sexually mature individuals. Length frequency data were used to characterize size structure of the population and to derive a selection ogive for the species based on the currently used cod-end mesh size of 38 mm in the fishery. Results suggest that even though mature individuals were encountered all year round, the main breeding events for L. gossei occur in March and September. It was also determined that the size at which 50% of female L. gossei reached maturity (L50%) was 137 mm total length, while 100% sexual maturity was reached at 170 mm total length. The size at first maturity was 122 mm total length, while the steepness parameter of the maturity ogive, (δ) was 7 mm. Distribution of sizes in the sample was roughly symmetric about a mean of 145 mm total length, while the size at 50% selection was 120 mm total length. These results are discussed in the context of their implications on the management of the demersal trawl fishery in the Southeast Arm currently dominated by L. gossei, given the misalignment of the closed season currently in October to December and the inadequacy of the cod-end mesh size of 38 mm. The main conclusion of this study was that the current cod-end mesh size in the fishery is too small and should be adjusted to prevent growth overfishing. A proposal is made for a closed season for the trawl fishery from March to April.

Changes in the hypothalamus in relation to testicular cells during growth, maturation and spawning phases in the brackishwater teleost Liza parsia (Hamilton, 1822)

In the present investigation, different cell types in the hypothalamus of the goldspot mullet Liza parsia (Hamilton, 1822) were characterised on the basis of their arrangement, distribution and tinctorial properties. The hypothalamic neurosecretory system of L. parsia is made up of two nuclei rich areas viz., nucleus pre-opticus (NPO), nucleus lateralis tuberis (NLT) and their axonal pathways. The NPO is vertically organised and the cells are arranged in an oblique plane on either side of the third ventricle. The larger cells viz., pars magnocellularis (PMC) are dorsally placed whereas smaller cells, pars parvocellularis (PPC) are placed ventrally to the third ventricle. Fine thread like axons stained with chrome-alum-haematoxylin-phloxine (CAHP) extend from preoptic cells to the close proximity of blood capillaries. Cells of the NLT are paired and situated above the pituitary gland. The cells of NPO and NLT exhibited both quantitative and qualitative variations during different periods of the testicular maturation. During growth and maturation periods, cells of PMC and NLT were characterised by intense staining and dense homogeneous granules along with deposition of neurosecretory materials. During spawning period, slight decrease in staining affinity of the cells of PMC and NLT were recorded. Changes in the testes of L. parsia have been described according to variations in gonadosomatic index (GSI) values and frequency percentages of different male germ cells during growth, maturation and spawning phases.

Family Belonidae from the Suez Canal, Egypt: Age, growth, mortality, exploitation rate and reproductive biology

This is the first attempt to study the biological characteristics and basic population parameters of two important Belonidae species, Tylosurus acus and Tylosurus crocodilus from the Suez Canal. The length– weight relationship was estimated as W = 0.0005TL3.26 for T. acus and W = 0.0007TL3.21 for T. crocodilus. The growth parameters of T. acus were computed as L∞ = 79.85 cm, k = 0.44 year–1, t0 = –0.58 years, while the annual total, natural and fishing mortality were 1.70, 0.72 and 0.98 respectively with an exploitation rate of 0.58. While in T. crocodilus the VBGPs were L∞ = 113.0 cm, k = 0.30 year–1, t0 = –0.46 years, the annual total, natural and fishing mortality were 1.27, 0.51 and 0.76 respectively with an exploitation rate of 0.60. The female's length at first maturity of T. acus was estimated to be 47.3 cm and 51.7 cm for T. crocodilus. Monthly variations in Gonado-somatic index revealed that the spawning season of the two species takes place in spring. Results of exploitation rate indicated that the T. acus and T. crocodilus are fully exploited.