Higher Gonadosomatic Index Research Articles

Population dynamics and seasonal variation in biological characteristics of black sea bream (Acanthopagrus schlegelii) in Zhanjiang coastal waters, China

This study examined the population dynamics and seasonal variation (winter-summer) in the biological characteristics of black sea bream (Acanthopagrus schlegelii) in Zhanjiang coastal waters, China. Key growth parameters were estimated using the von Bertalanffy growth model, revealing an asymptotic length (L∞) of 505.05 mm and a growth coefficient (K) of 0.26 year-¹, with an estimated longevity of 11.24 years. Mortality analysis showed a total mortality rate (Z) of 0.35 year-¹, primarily driven by natural causes (M = 0.33 year-¹) with minimal fishing impact (F = 0.02 year-¹), resulting in a low exploitation rate (E) of 0.05. Length-weight relationship (LWR) analysis indicated positive allometric growth in females and nearly isometric growth in males, with significant seasonal variations in condition factors (K). Yield Per Recruit (YPR) analysis identified a maximum sustainable exploitation rate (Emax) of 0.421, with a conservative management approach suggested at E0.1 = 0.355. Seasonal variations in reproductive indices, with higher Gonadosomatic Index (GSI) and Hepatosomatic Index (HSI) in winter, highlight the species’ reproductive cycle. The findings suggest that Acanthopagrus schlegelii is stable, with low fishing pressure. Seasonal GSI and HSI variations suggest fisheries management should time fishing to reduce impacts on reproductive success. Maintaining exploitation rates below Emax is essential for sustainable management, contributing valuable insights for fisheries conservation in coastal China.

Unraveling the spawning and reproductive patterns of tomato hind grouper, Cephalopholis sonnerati (Valenciennes, 1828) from south Kerala waters.

The objective of this study is to provide information on the reproductive biology of tomato hind grouper, Cephalopholis sonnerati (Valenciennes, 1828) for conservation and management purposes. Fish caught by artisanal fishermen from September 2019 to August 2021 were analysed. A total of 280 females, 31 males, and 4 transitional and 178 sex-undetermined fish were analysed. The female to male sex proportion was 9:1, and the fish reached a maximum total body length of 38.5 and 54.5 cm for females and males, respectively. The following microscopic stages were identified: immature, developing, ripe, running ripe/releasing, and spent in both males and females. Several asynchronous development patterns were observed in the studied gonads, including multiple oocyte stages and early and advanced stages of sexual transition. High gonadosomatic index (GSI) for both males and females was recorded in March, May, and November. Running ripe and releasing stages in females were identified in the months from March to June, which indicates the spawning season. The absolute and relative fecundity of the species ranged from 162,723 ± 207,267 and 239 ± 285, respectively. An exponential relationship was found between fecundity and total body length (TL), fecundity and total body weight (TW), and fecundity and gonad weight (GW).

Insights into reproductive dynamics and feeding biology of Sphyraena putnamae Jordan and Seale, 1905 exploited in the Indian EEZ

The sawtooth barracuda Sphyraena putnamae, widely distributed in the Indo-Pacific region, isone of the commercially important barracuda species exploited by trawls in the Indian EEZ.The present study examined 2,135 S. putnamae collected during 2014-2020 from differentfish landing centres along the Indian coast, to elucidate their reproductive and feedingbehaviour. The fork length of sampled females and males varied from 12.5 to 130.9 cm and16.5 to 90.0 cm respectively. Negative allometric growth was observed with a significantdifference (p<0.05) between the sexes. The observed sex ratio (Female:Male) was 1.23:1,indicating the dominance of females. Size at sexual maturity for females and males wereestimated at 55.3 and 45.4 cm fork length respectively. The higher proportion of spawningcapable individuals and higher gonadosomatic index (GSI) values in females observedduring March to May and November-December revealed the bimodal and protractedspawning nature of this species. Absolute fecundity increased with fork length and weightand varied from 70,080 to 10,18,068 oocytes with an average of 3,16,568 oocytes. Thestomach vacuity index of females and males was 49.09 and 47.92% respectively. Fifty-nineprey items were identified in the diet, with a predominance of fishes confirming S. putnamaehas a piscivorous feeding behaviour. Keywords:Management, Protracted spawners, Piscivore,Sawtooth barracuda, Sex ratio

Biochemical composition and condition of wild blackfin snook Centropomus medius through the reproductive cycle

The blackfin snook, Centropomus medius, is a valuable fish in American and Mexican markets, mainly from catches. Nonetheless, information and studies about the biology of this species still need to be made available; thus, its aquaculture should be developed. This study aimed to describe the seasonal changes of proximate composition during a reproductive cycle of C. medius, analyzing differences between tissues and their changes related to the reproductive process. The snook specimens were collected in Magdalena Bay, Baja California Sur, Mexico, and measured every month from September 2001 to November 2002. Liver, gonads, muscle tissue, and intraperitoneal fat (IPF) were sampled and weighed. The gonadosomatic index (GSI), hepatosomatic index (HSI), IPF ratio, and condition factor index (K) were calculated. The biochemical composition was analyzed in the gonad, liver, and muscle. The reproductive period (RP) of wild C. medius in Baja California Sur, Mexico, was from June to December. The spawning period was recorded at summer temperature (25-30°C) and photoperiod (>13 h daylight) starting in September. High GSI values (gonad development), low HSI values (lipid reserve mobilization), low IPF, and low K ratio were related to elevated temperatures. Moreover, variations were observed in protein, total lipid, triglycerides, and glycogen content in muscle, liver, and gonad according to the reproductive phase. A positive correlation was demonstrated between protein contents in muscle, gonad, and K, with lower concentrations during RP, while liver protein composition showed an opposite pattern. Lipids were mainly present in the liver, and the concentration decreased during RP while muscle increased. The results obtained in this study show differences in the proximate analyses in the liver, muscle, and gonads throughout the year concerning different phases of the reproductive cycle, indicating a great dependence of this process on the mobilization of reserves during C. medius reproduction. Therefore, understanding the feeding requirements to pursue the management of this species in captivity for aquaculture development is greatly important.

The Reproductive Biology of Puye (Galaxias maculatus) under Experimental Culture.

This study determines the reproductive patterns of puye (Galaxias maculatus) under culture conditions. A population of 567 wild fish was caught in the Cautín River, Chile, and held in captivity for four years. Mortality, sex ratio, gonadosomatic index (GSI), sexual maturity stages, spawning period, type and frequency of spawning, and fecundity were measured. The fish grew throughout the experimental period, with the fastest rate during the first half of the first year of life. The highest mortality occurred during the first three months of the experiment and during the spawning season. The sex ratio was almost 1:1 (female:male). First sexual maturity was reached at one year of age, with an average weight of 0.85 ± 0.01 g, total length of 4.85 ± 0.16 cm, and condition factor 0.0074. The highest GSI in both females (12.14 ± 0.74) and males (17.7 ± 2.70) was recorded in August. Nevertheless, the females spawned 3 to 10 times between September and February, with the highest reproductive peak between September and October. The number of embryos per female per day varied from 1 to 429, while the total number of embryos per female during the entire season evaluated varied from 163 to 1044. There was a high correlation (r = 0.82) between absolute fecundity and body weight. Although further studies are needed in this field, these results are basic for establishing future reproductive programs in captivity as a strategy for sustainable fisheries and aquaculture management.

Bangana devdevi, a Native Carp of the Himalayan Biodiversity Hotspot: Reproductive Biology and Hormonal Breeding Efforts for Conservation and Aquaculture Promotion

Efficient conservation efforts for valued fish species such as Bangana devdevi, a medium‐sized minor carp prevalent in Southeast Asian countries, can be facilitated through well‐established artificial breeding techniques. This study aimed to investigate the reproductive biology of B. devdevi and focused on optimizing hormone dosages for breeding purposes for the first time. The research findings indicated that the highest gonadosomatic index (GSI) for males (1.17) was observed in August, while for females, it peaked in July (2.24). Female fish exhibited absolute fecundity ranging from 2089 to 26287 eggs, corresponding to body weights ranging between 10.46 and 153.73 g. The relative fecundity ranged from 170 to 298 eggs g−1 of body weight. To induce breeding, female brooders were administered Gonopro‐FH hormone through three experimental groups: G‐FH_0.4, G‐FH_0.5, and G‐FH_0.6, with doses of 0.4 mL, 0.5 mL, and 0.6 mL·kg−1 of body weight, respectively. Spawning occurred within 6–10 h after hormone administration. Among these groups, G‐FH_0.5 exhibited the highest fertilization rate (94.25%) and hatching rate (89.03%), significantly surpassing the rates observed in G‐FH_0.4 and G‐FH_0.6 (p < 0.05). This study provided valuable insights into the reproductive biology of B. devdevi and emphasized its potential application in developing management and conservation strategies for this species in rivers and tributaries. Furthermore, the knowledge gained from induced breeding holds promise for future large‐scale seed production initiatives.

Reproductive Cycle of the Sea Urchin Paracentrotus lividus (Lamarck, 1816) on the Central West Coast of Portugal: New Perspective on the Gametogenic Cycle

A population of sea urchins, Paracentrotus lividus, from the central west coast of Portugal was studied to characterise their reproductive biology and possible relationships with environmental factors. An annual gametogenic cycle was found, with a broad spawning season, from May to November, according to a relatively synchronous gamete maturation process. Depending on the environmental factors (temperature, photoperiod), two separate periods could be distinguished, with more individuals maturing and spawning at the same time. When this happened, the first event evolved when temperature rose to a critical point, and the second occurred afterwards, when temperature decreased significantly. Notwithstanding, it was found that individuals matured later than previously described for other populations (e.g., north of Portugal), mostly in late spring, with a higher gonadosomatic index in May. A new classification scale was proposed for identifying the stages of P. lividus gametogenic cycle, based on new findings. It contributed to its simplification and easier comprehension. This study provides useful information for a differentiated sustainable management of P. lividus, according to local conditions. Establishing a closed harvesting season might be considered, based on the differences observed between Portuguese populations and other European ones.

Reproductive biology of the mackerel scad, Decapterus macarellus (Cuvier, 1833), in the Sulawesi Sea, Indonesia

Indonesia is the second largest fishery producer in the world, producing many small pelagic fish. To improve information for sustainable fishery management in the Sulawesi Sea, we examined the reproductive biology of the main target species, the mackerel scad Decapterus macarellus (Cuvier, 1833). Between May 2020 and March 2021, we collected 1267 mackerel scads from two landing sites in northern Sulawesi. These fish ranged from 13.4 to 38.2 cm in total length, and their sex ratio, length at first maturity (Lm), reproductive periodicity, and potential spawning grounds were studied. An equal male to female (M:F) sex ratio of 0.98:1.00 was osberved. The lengths of males and females at first maturity (Lm) were 22.59 and 21.62 cm, respectively. The mackerel scads spawned throughout the year, peaking in January, March, May, and September. Spawning occurs mainly during the first quarter of the moon’s phase. Most mature individuals with a high gonadosomatic index were found near Tumumpa Dua and the northern and western coasts of the Sangihe and Siau Islands, suggesting that there are specific locations where mackerel scads spawn. Fishery managers can use this information to implement temporary and regional fishing closures to develop sustainable fishing practices for small pelagic fish species.

Effects of dietary arachidonic acid on growth, gonadal development, and tissue fatty acid composition in the hermaphroditic swamp eel (Monopterus albus)

10-week dietary arachidonic acid (ARA) feeding trials were conducted in 14-month-old swamp eel (Monopterus albus) to evaluate the effects on growth performance, gonadal development, tissue fatty acid profile, and gene expression related to lipid metabolism. The results showed that swamp eels fed diets supplemented with 1.4% or 2.8% ARA had a significantly higher weight gain rate (WGR) and specific growth rate (SGR) than those fed the control diet. Dietary supplementation with ARA improved oocyte development and maturation. Higher gonadosomatic index (GSI) was detected in 1.4% and 2.8% ARA groups. ARA supplementation delayed sexual reversal in females. The ARA content in the muscle, liver and gonads increased with increasing dietary ARA concentration; however, ARA supplementation significantly reduced the transcriptional expression of lipid metabolism-related genes in the gonads, such as fad2, pla2g4a, and elovl5. Serum alanine aminotransferase (ALT) levels in the ARA 1.4% group were significantly lower than those in the control and ARA 2.8% groups. Total cholesterol (T-CHO) and triglyceride (TG) levels were significantly lower in the 1.4% and 2.8% ARA groups than in the control group. Catalase (CAT) and high-density lipoprotein cholesterol (HDL-C) increased with dietary ARA concentrations. This study found that dietary ARA is important for improving growth, Ovarian development, and antioxidant capacity in swamp eels.

An insight into the fishery, biology and population dynamics of Auxis rochei (Risso, 1810) along the south-west coast of India

Auxis rochei is one of the coastal tunnies contributing substantially to the tuna landings inIndia, with an average (2014-2019) annual catch of 7210 t. Kerala stood first, with an annualaverage landing of 3176 t. The fishery comprised 14.5 - 39.6 cm fork length (FL) size groupswith a mean length of 27.64 cm and a major mode of 26 cm FL. The Length-weight (L-W)relationship of pooled fishes was expressed as W= 0.000003 L3.22 (r2= 0.91). The size at firstmaturity was estimated at 25.8 cm FL when the fish was 1.5 years old. The number of eggsper spawning ranged from 84,562 to 1,33,698 and the ova diameter ranged between 0.1and 0.6 mm, indicating asynchronous oocyte development with multiple spawning. Highergonadosomatic index (GSI) was recorded during April, May and June and coincided withthe minimum gastrosomatic index (GaSI). The recruitment pattern was bimodal, with variedintensity ranging from 0.79-17.89%. Growth was allometric and the von Bertalanffy growthequation derived was Lt=43.5(1-e-0.8(t+0.0212)). The growth performance index (ɸ) was 3.18 andthe longevity of the fish was estimated at 3.7 years. One-year-old plus fishes sustained thefishery (22 - 32 cm FL). Total mortality (Z), natural mortality (M) and fishing mortality (F)were estimated at 3.70, 1.40 and 2.30, respectively, with an exploitation rate (E) of 0.62and the exploitation ratio (U) of 0.60. Beverton and Holt yield per recruit (Y/R) and Biomassper recruit analysis indicated that the Emax was at 0.87, much higher than the present levelof exploitation, reflecting the sustainable fishery along the coast. Standing stock biomass(SSB) was estimated at 7215.7 t, and the spawning stock biomass formed 55.5% of the SSB.Thompson and Bell analysis indicated the MSY as 8125 t, at F-factor, 2.6. The biologicalreference points FCURR/FMSY (0.4) and BCURR/BMSY (1.5) were at safe levels, signifying the scopefor fishery enhancement. Keywords:Biological reference point, Fecundity, Growth, GSI,L-W relationship, Mean length, Mortality, SSB

MiR-155 Regulates Photoperiod Induced Gonadal Development in Atlantic Salmon (Salmo salar) by Targeting Brain-Derived Neurotrophic Factor

This study was designed to explore the impact of the photoperiod on the gonadal development and somatic growth of Atlantic salmon raised in recirculating aquaculture systems (RASs), with specific focus on the role that microRNA (miR)-155 plays as a regulator in the Atlantic salmon’s photoperiodic reproduction. These salmon were reared for 5 months under six different photoperiod regimens, including two with changing photoperiods (LL–SL = 24L:0D–8L:16D and SL–LL = 8L:16D–24L:0D) and four with constant photoperiods (24L:0D, 18L:6D, 12L:12D, and 8L:16D). The longer photoperiod groups (LL–SL and 24L:0D) were ultimately associated with higher gonadosomatic index (GSI) values and an increased proportion of mature fish relative to other exposure groups, indicating that the photoperiod positively impacted the Atlantic salmon’s gonadal development in RAS environments. Hypothalamic miR-155 expression in these Atlantic salmon was also found to be influenced by the photoperiod, showing a markedly decreased expression in salmon exposed to a long photoperiod and upregulation following rearing under a short photoperiod. Functionally, miR-155 was found to suppress the expression of gonadal axis-related genes, including FSH and GnRH, through its ability to target the brain-derived neurotrophic factor (BDNF) and to thereby regulate photoperiod reproduction. Overall, these results suggested that the photoperiod could regulate gonad development in Atlantic salmon with miRNA-155 being involved in this process by targeting the BDNF.

Arctic cod (Boreogadus saida) in fjord and glacial habitats: a collaborative study with Uummannap Kangerlua fishers

Arctic cod ( Boreogadus saida) (Lepechin, 1774) is often found in front of glaciers, which is the least studied of the species’ habitats. Uummannap Kangerlua and Sullorsuaq in West Greenland provide a unique opportunity to study Arctic cod in the glacial habitat, as they are among the few places with a directed Arctic cod fishery. Inuit fishers from these fjords regularly catch Arctic cod as fresh bait for the Greenland halibut ( Reinhardtius hippoglossoides) (Walbaum, 1792) longline fishery, the main economic activity in the region. We collaborated with the fishers to learn about Arctic cod through interviews and collection of fish samples. Ten informants provided information on fishing areas, fishing methods, interannual variability in the catches, relationships with temperature and sea ice, and reported a spawning area near Saattut. One of the two samples collected contained only 21% males, which were longer, heavier, older, and had a higher gonadosomatic index than females. This skewed sex ratio may result from size-selective predation or spawning migration. Collaboration with fishers provided important baseline information on Arctic cod in fjord and glacial habitats. Continued efforts could bring a better understanding of key aspects of Arctic cod that are relevant for all Arctic communities located near glacial fjords.

Male germ cell proliferation and apoptosis in sexually immature meagre Argyrosomus regius (Asso, 1801) treated with recombinant follicle stimulating hormone

The meagre Argyrosomus regius (Asso, 1801) is a marine fish species that has an increasing aquaculture production in Europe. Lowering the age at maturity of hatchery-produced juveniles would support meagre aquaculture by reducing time between generations in selective breeding programs and reducing industrial costs for broodstock maintenance. The aim of this work was to assess the effects of a treatment with recombinant follicle stimulating hormone (rFsh), produced in ovarian cells of Chinese hamsters, on male germ cell proliferation and apoptosis in sexually immature meagre. The rFsh-treated fish had higher gonadosomatic index, larger seminiferous tubules, more abundant luminal spermatozoa, a lower density of anti-PCNA positive single A spermatogonia, a higher density of anti-PCNA positive spermatocysts and a lower incidence of germ cell apoptosis than control groups. The present study demonstrated the effectiveness of the produced rFsh in stimulating testis development and spermatogenesis in pre-pubertal meagre. Moreover, the rFsh treatment proved to be highly efficient in removing the apoptotic block of spermatogenesis observed in juvenile meagre, allowing spermatogonial survival and progress towards meiosis. The administration of rFsh did not stimulate spermatogonial self-renewal, a process whose control still needs to be elucidated.

Recombinant Gonadotropins to Induce Oocyte Development In Vitro and In Vivo in the European Eel Anguilla anguilla

Commonly, female European eels are injected weekly with pituitary extract (PE) from carp (CPE) or salmon (SPE) to induce sexual maturation. However, a PE is a mixture of gonadotropins and other hormones that are not specific for eel and rapidly cleared from circulation. The aim of this study was therefore to test the effects of highly stable eel-specific recombinant gonadotropins (rGTHs) on oocyte development in vitro and in vivo in European eels. For the in vitro trial, the dose–effect responses of maturing eel oocytes on CPE and recombinant luteinizing hormone (rLH) were studied before and after 12 and 18 h of incubation. For the in vivo experiment, sexual maturation was stimulated by treatment with (i) CPE, (ii) recombinant follicle-stimulating hormone (rFSH) followed by CPE and (iii) rFSH followed by rLH. For the in vitro experiment, the expression of the nuclear progestin receptor 2 (pgr2) was induced by rLH, implying that rLH was preparing the oocyte for ovulation. For the in vivo experiment, the females treated with rGTHs had high gonadosomatic index (GSI) values (rFSH-CPE: 75, 77; rFSH-rLH: 80) in comparison with the females injected with CPE (50–60), suggesting that rFSH strongly induced vitellogenic growth. Larvae were produced for all treatment groups and for the first time by rGTH treatment alone but dose and timing still need optimization.

Reproductive potential of the blue crab spawning stock in Chesapeake Bay across eras and exploitation rates using nemertean worms as biomarkers

Assessments of reproductive potential and spawning history of marine and estuarine crabs are limited due to issues with determination of age and spawning history. The spawning stock of the blue crab Callinectes sapidus in Chesapeake Bay was heavily fished and declined in the 1990s. Management actions were implemented between 2001 and 2008 to reduce spawning stock exploitation and trigger recovery. Whether these actions impacted the demography of female spawners is unknown. We assessed demographics of overwintering mature female crabs in 1992-1996 and 2020-2022 by classifying them as first-year (imminent primiparous) or second-year (primiparous and multiparous) spawners based on presence of mature nemertean worms (Carcinonemertes carcinophila) in their gill chambers. We also investigated organismal and environmental predictors of second-year spawners. We provide the first annual estimates of the proportion of multi-year spawners at the population level. Management actions reduced exploitation rates by 41% after 2008, and the proportion of second-year spawners was greater than in the 1990s. Nonetheless, exploitation rate in a given year did not predict proportion of second-year spawners in the following year. Second-year spawners tended to be smaller females, or females with a high gonadosomatic index or longevity indicators (i.e. fouling by barnacles). High proportions of large, highly fecund, overwintering first-year spawners in the 2020s support the need for enhanced protection of females in spring to allow these females to spawn. Finally, nemertean worms are a useful, easily implemented tool to determine spawning history and age-specific reproductive potential of crabs that undergo a terminal molt prior to spawning.

Reproductive biology of paradise threadfin Polynemus paradiseus (Linnaeus, 1758) from Shibsa River in Bangladesh

The paradise threadfin, Polynemus paradiseus is one of the commercially important brackishwater finfish of the family Perciformes in Bangladesh. The present study aimed to investigate the reproductive biology of paradise threadfin from Shibsa River in Bangladesh. The fish samples (66) were collected from May 2021 to April 2022. The relationship between body weight (BW) and total length (TL) of sampled fish were analyzed with a non-linear power equation where R2 = 0.915 and ‘b’ value (3.22) indicates a positive allometric growth pattern. Linear relationship indicates gonad weight (GW) increases with the BW and fecundity increases with BW, TL, GW and gonadosomatic index (GSI). The highest GSI was recorded in June (11.10±0.91), whereas, the lowest in November (0.44±0.08). The maximum fecundity was found in June (32410±7790). Ovarian histology displayed different stages of oocyte development. Late yolk granule stage (LYGS) was found in the months of September-October and May-July, respectively. Based on the GSI, fecundity and ovarian histology, it was revealed that the spawning season of P. paradiseus was from May to October with a major peak in June and minor one in September. The knowledge on different aspects of reproductive biology of paradise threadfin would be helpful for planning captive breeding and to design sustainable management policies for conservation of this species in the south-west coast of Bangladesh.

Changes in Condition Factor, Hepatosomatic and Gonadosomatic Index of Yellowfin Tuna (Thunnus albacares) in Captivity

The necessity for tuna products in the world community continues to increase, while production relies only on catching, thus causing overfishing. Therefore, breeding technology to support tuna farming is fundamental to be developed. Yellowfin tuna farming in Indonesia has been successful in cultivating broodstock. This paper discusses biometric data that changes during cultivation, such as condition factor, hepato and gonadosomatic indexes compared with wild captured. Data were collected from young tuna to broodstock and compared with wild captured such as fork length, body, liver and gonad weight. The condition factor (K) of cultivated tuna (1.5-2.5) was higher compared with wild captured (1.5-2.0). Similarly, the value of cultivated tuna’s hepatosomatic index (HSI) was higher (0.63-1.14). In contrast, the gonadosomatic index (GSI) of wild captured yellowfin tuna was higher (>0.5) compared with cultivated yellowfin tuna in a circular concrete tank (0.4) but lower than that cultivated in a floating net cage (>1.4). Maintenance of broodstock in the tank with a lower GSI value means the number of eggs produced is relatively lower than its natural counterpart. At the same time, the high GSI value of cultivated broodstock in FNC shows better results than wild captured broodstock.

Lipid and Protein Content in Rainbow Trout in Relation to Gonadal Growth

Abstract The purpose of this study was to examine various lipid classes as well as the protein content in rainbow trout ovaries. A total of 80 samples of Oncorhynchus mykiss (Walbaum 1792) were collected from Kokernag and Verinag hatcheries (Jammu and Kashmir, India) between 2017 and 2019. The mature stage in female fish had the highest gonadosomatic index (GSI) and minimal GSI in the spent stage. Higher lipid content of the ovary was reported during the mature stage (36%), as compared to other pre-breeding stages. Similarly, lipid classes also showed fluctuation during the development of the ovary. The lipid classes, i.e. glycolipids, free fatty acids, cholesterol and triglycerides, had a higher content in the mature stage, while the phospholipid content was higher in the mature stage. The protein content was also higher in the mature ovary than in the other developmental stages. The study provides reference values for various biochemical parameters in rainbow trout that could be useful for population monitoring programs and for the development of diets and management methods for fish production under controlled conditions.

Transcriptome and targeted metabolomics revealed that cholesterol nutrition promotes ovarian development by regulating steroid hormone metabolism in swimming crab

Cholesterol, which acts as a substrate for the synthesis of ovarian sex hormones, could promote ovarian development. However, crustaceans cannot synthesize cholesterol and must obtain it from diet for growth, molt and gonadal development. Three isonitrogenous and isolipidic diets were formulated to contain 0.12%, 1.00% and 2.50% cholesterol, respectively. The results showed that dietary 1.00% and 2.50% cholesterol significantly increased percent weight gain (PWG) and specific growth rate (SGR), moreover, crabs fed diet with 1.00% cholesterol had the highest gonadosomatic index (GSI) among all treatments. Cholesterol (CHO) and triglyceride (TG) concentrations in tissues significantly increased with dietary cholesterol levels increasing from 0.12% to and 2.50%. Targeted metabolomics analyses indicated that crabs fed 1.00% cholesterol diet exhibited higher steroid hormones, such as progesterone, pregnenolone, estrone, estradiol and estriol than those fed the other diets. In addition, crabs fed the 1.00% cholesterol diet significantly up-regulated the expression of genes related to cholesterol transport, steroid hormone synthesis and ovarian development in hepatopancreas and ovary. Transcriptomics analyses revealed that DEGs (differentially expressed genes) in crabs fed 1.00% cholesterol diet were associated with “metabolism of xenobiotics by cytochrome P450″ and “progesterone-mediated oocyte maturation”. In conclusion, the results of present study demonstrated that dietary 1.00% cholesterol promoted growth and ovarian development by improving the cholesterol transport and steroid hormone synthesis for female swimming crabs.

Morphoregression and Reproduction Aspect of Bonylip Barb (<I>Osteochilus vitattus</I> Valenciennes, 1842) in Tamblingan Lake, Bali Island

Highlight Research Morphoregression and reproduction aspect of bonylip barb was analyzed Fork length more accurately to estimate the body weight Lm50 of bonylip barb in Tamblingan Lake was 116 mmTL Growth pattern is isometric Good reproduction aspect Abstract Bonylip barb (Osteochilus vitattus Valenciennes, 1842) is one of many native fish inhabiting Tamblingan Lake. The information about this species in Tamblingan Lake is rare which requires fulfilment in information gaps for the management of bonylip barb. The aims of this research were to find out the length-length relationship, length-weight relationship, length at first maturity, sex ratio, gonadal maturity stage, gonadosomatic index (GSI), fecundity, as well as spawning period and location in Tamblingan Lake. The fish sample was captured with experimental gillnet that was set in the afternoon and hauled in the next morning. Length and weight of every sample were taken. All samples were dissected to observe the sex and gonad. Fork length was the type of length with higher accuracy to estimate the body weight than the other length character. Growth pattern of this species was isometric. Lm50 of bonylip barb in Tamblingan Lake was 116 mmTL. Sex ratio of bonylip barb was imbalanced (1.00:0.82). Gonad maturity stage I-V was found during the research with GSI between 0.16-15.50 for male fish and 0.43-32.82 for female fish. The highest GSI was found in March, 15.50 for male fish and 32.73 for female fish. Mature fish were discovered in all stations in every month of sampling. The fecundity of bonylip barb ranged between 2,792-279,326 eggs. The length-length and the length-weight showed a strong relationship. The fish was isometric. Based on the growth pattern and the reproductive aspects, the population of bonylip barb in Tamblingan Lake was in good condition.