Changes In Gonadosomatic Index Research Articles

Structural modeling and gene expression analysis of phosvitinless vitellogenin (vgc) in the Indian freshwater murrel, Channa punctatus (Bloch, 1793)

Vitellogenin (Vg) is a female-specific egg-yolk precursor protein, synthesized in the liver of fish in response to estrogens. In the present study, complete gene of phosvitinless vitellogenin (vgc) was sequenced, its 3D structure was predicted and validated by web-based softwares. The complete nucleotide sequence of vgc was 4126 bp which encodes for 1272 amino acids and showed the presence of three conserved domains viz. LPD_N, DUF1943 and DUF1944. The retrieved amino acid sequence of VgC protein was subjected to in silico analysis for understanding the structural and functional properties of protein. mRNA levels of multiple vg genes have also been quantified during annual reproductive cycle employing qPCR. A correlation has been observed between seasonal changes in gonadosomatic index with estradiol levels and hepatic expression of three types of vg genes (vga, vgb, vgc) during ovarian cycle of murrel. During preparatory phase, when photoperiod and temperature are low; low titre of E2 in blood induces expression of vgc gene. A rapid increase in the levels of E2 favours induction of vgb and vga genes in liver of murrel during early pre-spawning phase when photoperiod is long and temperature is high in nature. These results suggest that among three vitellogenin proteins, VgC is synthesized earlier than VgA and VgB during oogenesis.

Annual reproductive cycle of a successful Lessepsian immigrant in the Eastern Mediterranean Sea, Pomadasys stridens (Forsskål, 1775) (Family: Haemulidae)

ABSTRACT The striped piggy, Pomadasys stridens (Forsskål, 1775), is one of the successfully colonized Lessepsian immigrants entering the Mediterranean through the Suez Canal. This study was carried out to understand to what extent the reproduction strategy adopted by this species had played a role in its successful establishment. The study is based on samples collected during the monthly trawl surveys conducted between January 2017 to November 2020 in the Northeast Mediterranean. The annual gonadal development cycle was estimated by observing the Gonadosomatic Index changes. Seasonal patterns in energy intake and allocation were acquired from Hepatosomatic, Digestosomatic, and Relative Body Condition indices. The results indicated that the species has prolonged gonadal development periods, during which spawning occurs twice, in early summer and at the onset of the winter. A comparison of all indices involved indicated that the species feeds and develops gonads at the same time before summer spawning, feeds heavily and stores energy during the warmest period, and uses the stored energy in the winter spawning. As these features do not differ much from their congenerics inhabiting the geography they originated from, it is suggested that it was not the ecological plasticity of the species that is the basis of their success but the reproductive traits they have fitted well to the Mediterranean Ecosystem.

Biology of the Reproduction of Mugilidae Neochelon falcipinnis (Valenciennes, 1836) in the Protected Marine Area of Niamone-Kalounayes (Casamance Estuary)

The reproduction of Neochelon falcipinnis was studied in the Marine Protected Area (MPA) of Niamone-Kalounayes located in the Casamance estuary (Senegal) from July 2021 to June 2022. The results of this study are presented after twelve (12) months of experimental seine fishing. Reproductive parameters such as length-weight relationship, condition factor (K), sex ratio (SR), gonadosomatic index (GSI) and size at first maturity (Lm50) were determined. A total of 386 individuals (150 males, 221 females and 15 of undetermined sex) were sampled. The sex ratio was in favour of females (0.68 or 1:1.47). The length-weight relationship showed a minor allometric growth with allometric coefficient b values of 2.70 for both sexes combined, 2.60 for males and 2.79 for females. The ANOVA test showed no significant difference in condition factor in males (P > 0.05). In contrast, in females, there was a significant difference at the beginning of the cold season (P < 0.05). The monthly change in gonadosomatic index associated with the different stages of sexual maturity indicated a breeding period in the dry season (May, June and July). Peaks of sexual maturity are observed in June for both sexes. Sizes at first sexual maturity were 18 cm for males and 19 cm for females. These results, obtained provide information on the reproduction of Neochelon falcipinnis that can help in decision-making for better management of the resource.

Molecular characterization of the Ftz‐f1 gene in redclaw crayfish Cherax quadricarinatus and its potential role in ovarian development

Ftz-f1 was a member of the NR5A-family nuclear receptors, and previously predicted to be participated in the complex ovarian processes. In this study, we characterized the full-length cDNA of Ftz-f1 with an open reading frame of 1746 bp encoding 581 amino acids in the redclaw crayfish, Cherax quadricarinatus (CqFtz-f1). Amino acid alignments and structural prediction uncovered that two highly conserved domain, DBD (DNA binding domain) and LBD (ligand binding domain) were identified, which shared with other members of nuclear receptors family. Tissues distribution showed that CqFtz-f1 exhibited sexually dimorphic expression pattern with a higher transcript level in ovary. Staging of ovarian development was conducted, which to be divided into four different stages by external feature and histology analysis. The changes of GSI (Gonadosomatic index) were in accordance with the mRNA expression of CqFtz-f1 during the reproductive cycle. In addition, both eyestalk ablation and β-oestradiol (E2) injection significantly increased the expression levels of Ftz-f1 and vg (vitellogenin). Furthermore, treatment with CqFtz-f1 dsRNA injection generated distinct effects on the expression of vg, suggesting that CqFtz-f1 might have positive effects on ovarian development by regulating vg expression in the redclaw crayfish.

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.

Investigation of sexual maturity and change in gonadosomatic index of sex riversed rainbow trout (Oncorhynchus mykiss) treated by oral 17 alpha methyl testosterone

Investigation of sexual maturity and change in gonadosomatic index of sex riversed rainbow trout (Oncorhynchus mykiss) treated by oral 17 alpha methyl testosterone

The effect of lipid-enriched Artemia franciscana on reproductive performance of broodstock and larval quality of Pacific white shrimp Litopenaeus vannamei

Broodstock maturation diets are an important component of shrimp hatchery management, since the nutritional status of spawners can impact on gonadal maturation, egg fecundity, embryo hatchability and overall larval quality. The ability to manipulate the biochemical composition of Artemia to deliver key nutrients to cultured animals has rendered their inclusion in broodstock feeds increasingly common. Lipid enrichment of Artemia franciscana to boost their unsaturated fatty acid content is a standard procedure. During this study, frozen, lipid-enriched adult Artemia biomass, squid and mollusc were fed to Litopenaeus vannamei broodstock to investigate the suitability of enriched Artemia as a maturation diet for the species and elucidate the role of essential fatty acids in the reproductive performance of the shrimp. Four lipid enrichment levels: PUFA (P group), MUFA (M group), HUFA (H1and H2 groups), un-enriched (NE group), No-Artemia (NA group), were fed to L. vannamei over 45 days. Significant differences in weight gain and specific growth rate were observed. Greatest mean SGR was recorded for shrimp of P-group as well as greatest mean final weight on day 45, while the lowest mean SGR was found for shrimp fed Diet NA. The fecundity of the broodstock shrimp fed diets either H1 or H2 increased compared with that of the shrimps fed NA (p<0.05). Significant differences in the hatching rate were observed. Changes in gonado-somatic index (GSI) of broodstock during ovarian maturation were very pronounced, but changes in hepato-somatic index (HSI) were not significantly different between the broodstock groups.

Influence of Climatic Factors on the Interannual Changes of Gonadosomatic Index of the Red Mullet Mullus barbatus ponticus in the Coastal Crimean Waters

The analysis of the influence of climatic factors on the interannual changes of the gonadosomatic index (GSI) of the red mullet Mullus barbatus ponticus, which inhabits the coastal waters of Crimea, was carried out. The dependence of the development of the reproductive system of the red mullet, determined by the gonadosomatic index, on temperature was revealed. It was found that the correlation coefficient between changes in the average temperature during the spawning and the GSI index is r = 0.98 for females and r = 0.97 for males. The maximum monthly average GSI values were observed in females and males of the M. barbatus ponticus, accordingly, in June, 4.29 and 3.76% and in July – 4.83 and 4.17%. An analysis of the size composition of the fish showed that the females are larger than males. For females, the predominant size group is 10.0–11.0 cm, and for males 9.0–10.0 cm. It was found that the red mullet, living in the coastal waters of the Crimea, has a slight positive allometric growth. A comparison in the developmental features of the red mullet that lives in different regions of the Black Sea-Mediterranean basin was made and the differences in the change in the GSI and other parameters are analyzed.

Toxicity of the aquatic herbicide, reward®, on the fathead minnow with pulsed-exposure proteomic profile

The objectives of this study were to assess the lethal and sub-lethal effects of the aquatic herbicide commercial formulation, Reward® (373 g/L DB), using application scenarios prescribed by the manufacturer. Specifically, a 14 d period between applications of Reward® in a water body undergoing treatment is required, yet the effects of these ‘pulse’ exposure scenarios on aquatic wildlife such as fish are unknown. In the first experiment early life stage FHM were exposed to a continuous DB concentrations from 0.105–12.6 mg/L which yielded a larval 7 d LC50 of 2.04 mg/L as well as a significant decrease in body mass (25.0 ± 11.6%) at the 1.18 mg/L Reward® concentration. In a second experiment, FHM larvae were exposed for 24 h and then reared in clean water for 14 d followed by a second 24 h exposure to Reward®. The 16 d LC50 value was 4.19 mg/L. In a third experiment, adult FHM were exposed in a pulse/discontinuous manner to Reward® with a calculated 21 d LC50 value of 6.71 mg/L. No significant changes in gonadosomatic index or fecundity of the F1 generation's hatch success were found when eggs from exposed adults were then reared in clean water. Proteome analyses of whole FHM larvae from the discontinuous/pulse exposure showed the primary gene ontology molecular functions of the proteins in fish exposed to 3.78 mg/L DB that resulted in ~30% mortality with positive or negative differential abundance (p-value < .2) were: structural molecule activity; identical protein binding; structural constituent of cytoskeleton; ion binding; calcium ion binding; cytoskeletal protein binding; actin binding; and, ATP binding. These findings suggest that concentrations causing adverse effects occur above the maximum concentration predicted by the manufacturer when applied according to the label (i.e. >0.37 mg/L).

Reproductive characteristics of the freshwater shrimp, Macrobrachium macrobrachion (Herklots, 1851) in the water bodies of Benin, West Africa

Abstract The palaemonid shrimp Macrobrachium macrobrachion is widely distributed in coastal rivers, estuaries and inland waters of West Africa. This species is economically important because it is the one of the two main freshwater shrimp commercially exploited by artisanal fisheries in southern Benin, besides showing great potential for aquaculture. Despite this, little is known about its reproductive biology in the natural environment. Considering these facts, the present study aimed to establish some breeding parameters for M. macrobrachion in Benin. Overall, 2424 specimens were collected between May 2015 and October 2016. Monthly changes in gonado-somatic index (GSI) and hepato-somatic index (HSI) suggest that the breeding season runs from July to October. In the Ouémé River Delta, the estimated size at first maturity is 8.16 cm TL in females, while it is 7.47 cm TL in males. In the Mono River/Grand-Popo Lagoon complex, the size at first maturity is 7.27 cm TL in females while it is 6.56 cm TL in males. The structure of the ovary as observed in females from either site just before spawning, shows the presence of two types of oocytes at different sizes and various developmental stages. Analysis of such ovarian structure suggests that M. macrobrachion has a synchronous oogenesis with a breeding season limited to a few months of the year. Fecundity was found to be between 3144 and 26 489 eggs in the Ouémé Delta, while it goes from 3124 to 22 660 eggs in the Mono River/Grand-Popo Lagoon complex. The present study provides important information on the reproductive biology of M. macrobrachion and of freshwater shrimp in general, and can also serve as a significant foundation for the aquaculture of species of freshwater shrimp.

The Growth and Ovarian Development Pattern of Pond-Reared Swimming Crab Portunus trituberculatus

The most common method for farming swimming crab Portunus trituberculatus in China is pond culture; however, their growth performance and ovarian development under these conditions are unclear. This study was conducted to investigate growth parameters, gonadosomatic index (GSI), hepatosomatic index, and monthly variation in the ovarian development of pond-reared female P. trituberculatus. The results showed (1) a significant increase in body weight (BW) and carapace width (CW) of female P. trituberculatus mainly during June to October, and the highest growth rate and specific growth rate of BW and CW were found during June to July. In addition, a significantly positive correlation was also found between BW and CW for pond-cultured P. trituberculatus females; (2) GSI increased significantly during ovarian development of pond-reared female P. trituberculatus and the mean GSI of ovarian stage I was 0.32%, whereas the mean GSI of ovarian stage V reached 7.92%; (3) Female P. trituberculatus started their pubertal molt at the end of July and the peak pubertal molt occurred from mid-August to early September; females nearly completed their pubertal molt in mid-October. Before pubertal molt, ovarian development of pond-reared P. trituberculatus was mainly at ovarian stage I during July to August; after the pubertal molt, females developed their ovaries quickly, with more than 80% at ovarian stage III inOctober. A second period of rapid ovarian development occurred at the end of January to the end of February, with a mean GSI reaching 5.25% at the end of February. From February to the end of March, no significant GSI changes were observed in female P. trituberculatus, indicating that the ovarian status of pond-reared female P. trituberculatus matured by the end of February.

Comparative Gametogenesis and Biochemical Differentiation of Goatfish (Parupeneus heptacanthus and Parupeneus cyclostomus) from Red Sea

Red Sea’s goatfish (Mullidae), locally referred as ‘Sultan Ibrahim’, are a popular recreational fish that also supports neighboring commercial markets. The present study compares spermatogenesis, oogenesis and gonad structure, in two species of goatfish from Jeddah coast. The reproductive parameters including changes in gonado-somatic index (GSI),and spawning seasons were analyzed for Parupeneus heptacanthus (cinnabar goatfish) and Parupeneus cyclostomus (goldsaddle goatfish). P. heptacanthus spawn from February to June and P. cyclostomus spawning season begins from August to September. Remarkable difference in the egg size has been observed P. heptacanthus had the egg diameter (325.9 μm), while the smallest one is P. cyclostomus (209.6 μm) when compared to other species of Mullidae. P. heptacanthus was observed with largest flagellum length (8.7 ± 0.2 μm). The ultrastructure revealed some common features in both species like oval ova; further the ovarian follicular epithelium consists of two layers, an inner granulosa layer with zona radiata under them and an outer theca layer. Centrioles of both species consist of the typically arranged nine triplets (9 + 0) of microtubules. The external lay of zona radiata is thinner than internal one. Disparity in protein patterns of muscle and gonads were observed in the present study. There was also variation in the number of specific bands for each species in both protein soluble muscle and gonads. The histology results reported gonads to be typically gonochoristic and exhibited asynchronous development of oocytes in the ovary. The outcome of this study has yielded essential information of some of the imperative reproductive biology of P. heptacanthus and P. cyclostomus.

Effects of cartriz on ovarian histopathology of Channa punctatus (Bloch).

Indiscriminate use of pesticides including cartriz for getting better result in agriculture, has ultimately affected the aquatic biota in general and fishes in particular. The present investigation is aimed to study the adverse effects in the histological make up and gonado somatic index(GSI) of a fresh water fish, Channa punctatus (Bloch) exposed to sublethal concentration of carbamate pesticide, cartriz for different ovarian cycle. The pesticide produced deleterious changes in the ovarian structure and also caused significant changes in GSI, revealing its toxic nature. Parallelly a central set of experiment was kept for observation without any pesticide. Hence it is suggested to use cartriz within prescribed level, to save the environment

A comparative gametogenesis and biochemical differentiation of goatfish (Family: Mullidae) from the Red Sea

Comparative study between few species of goatfishes (Mullidae), locally called Sultan Ibrahim, has been investigated from Jeddah coast. The present study compares gonad structure, oogenesis and spermatogenesis in three species of goatfish. The various stages are similar in the different species, but differ in time of spawning. The reproductive biology of three goatfishes, Mulloidichthys flavolineatus (1 black blotch), Mulloidichthys flavolineatus (3 black blotches), Mulloidichthys vanicolensis, were examined. A macroscopic and histological examination of the gonads demonstrated that all the three species are typically gonochoristic. Species-specific reproductive parameters including male stages, changes in gonado-somatic index (GSI), classification of oocyte stages were analyzed for each of the three targeted species. All three species have asynchronous ovary. The spawning season for the three studied species differ from one species to another i.e., the spawning season for M. vanicolensis females and males from April to July; M. flavolineatus, (1 black blotches) for both sexes from May until December; for M. flavolineatus (3 black blotches) showed a peak in May to early October for both sexes. Ultrastructurally the mature spermatozoon’s head shape appears like a computermouse, the tiny mid-piece consist two mitochondria and a flagellum. The chromatin, within the nucleus is electron-dense and homogenous in M. flavolineatus (with one black blotch), while the chromatin is granular in (M. vanicolensis and M. flavolineatus (3 black blotches)). The posterior region of the nucleus is deeply penetrated by the nuclear fossa which contains, the basal part of flagellum and centriolar complex. The ultrastructure of the eggs of the three Mullidae species is circular in shape and contains a simple, circular micropyle. The ovarian follicular epithelium of the three Mullidae species consists of two layers, an outer theca layer and an inner granulosa layer with zona radiata under them. Zona radiata consists of 2 layer-interna and externa. Zona radiata interna is thicker than zona radiata externa. Differences in protein patterns of muscles and gonads were observed in the present study.

Seasonal Variation in Reproductive Condition of the Pecos Bluntnose Shiner (Notropis simus pecosensis)

Abstract. Reproductive strategies vary among freshwater fishes. Information on reproductive characteristics is important for water managers' efforts to protect and recover imperiled species. We describe aspects of the reproductive ecology of Pecos Bluntnose Shiner (Notropis simus pecosensis). We determined gonadosomatic index, examined ovarian condition, and counted mature ova to determine the seasonal reproductive timing and duration of Pecos Bluntnose Shiner in the Pecos River, New Mexico. Monthly changes in gonadosomatic index, ovarian stage, and number of mature ova per female suggest that Pecos Bluntnose Shiner has a reproductive season extending from April through September, with a peak occurring in June and July. In July, 93% (n = 44) of female Pecos Bluntnose Shiner were in reproductive condition, regardless of size. The highest number of mature ova counted (1498) was observed in a 59.5-mm (standard length) female from June 2009. Peak spawning activity coincides with sustained water releases from ...

Gonadal Development, Spawning and Plasma Sex Steroid Levels of the Indoor Cultured Grunt, Hapalogenys nitens

ABSTRACTThe gonadosomatic index (GSI), gonadal development and changes in hormones in plasma level of the indoor cultured grunt (Hapalogenys nitens) were investigated by histological study from August 2011 to October 2012. The GSI showed similar trends with gonad developmental stages during the culture periods. Changes in plasma level of estradiol-17β of female H. nitens reached the highest value before the spawning period, and seasonal changes in plasma level of estradiol-17β were similar in trends of oocyte developments and GSI changes. Testosterone levels of male H. nitens reached the highest value before and after the spent stage. Ovarian developmental stages of H. nitens could be classified into early growing stage, late growing stage, mature stage, ripe and spawning stage, recovery and resting stage. The testicular developmental stages could be divided into growing stage, mature stage, ripe and spent stage, and recovery and resting stage.

Gonadal Development, Spawning and Plasma Sex Steroid Levels of the Indoor Cultured Grunt, Hapalogenys nitens.

The gonadosomatic index (GSI), gonadal development and changes in hormones in plasma level of the indoor cultured grunt (Hapalogenys nitens) were investigated by histological study from August 2011 to October 2012. The GSI showed similar trends with gonad developmental stages during the culture periods. Changes in plasma level of estradiol-17β of female H. nitens reached the highest value before the spawning period, and seasonal changes in plasma level of estradiol-17β were similar in trends of oocyte developments and GSI changes. Testosterone levels of male H. nitens reached the highest value before and after the spent stage. Ovarian developmental stages of H. nitens could be classified into early growing stage, late growing stage, mature stage, ripe and spawning stage, recovery and resting stage. The testicular developmental stages could be divided into growing stage, mature stage, ripe and spent stage, and recovery and resting stage.

Modulation of aromatase activity as a mode of action for endocrine disrupting chemicals in a marine fish

The steroidogenic enzyme aromatase catalyzes the conversion of androgens to estrogens and therefore plays a central role in reproduction. In contrast to most vertebrates, teleost fish have two distinct forms of aromatase. Because brain aromatase activity in fish is up to 1000 times that in mammals, fish may be especially susceptible to negative effects from environmental endocrine-disrupting chemicals (EDCs) that impact aromatase activity. In this study, the effects of estradiol (E2), ethynylestradiol (EE2), octylphenol (OP), and androstatrienedione (ATD) on reproduction and aromatase activity in brains and gonads from the marine fish cunner (Tautogolabrus adspersus) was investigated. The purpose of the study was to explore the relationship between changes in aromatase activity and reproductive output in a marine fish, as well as compare aromatase activity to two commonly used indicators of EDC exposure, plasma vitellogenin (VTG) and gonadosomatic index (GSI). Results with E2, EE2, and ATD indicate that aromatase activity in cunner brain and ovary are affected differently by exposure to these EDCs. In the case of E2 and EE2, male brain aromatase activity was signficantly increased by these treatments, female brain aromatase activity was unaffected, and ovarian aromatase activity was significantly decreased. Treatment with the aromatase inhibitor ATD resulted in significantly decreased aromatase activity in male and female brain, but had no significant impact on ovarian aromatase activity. Regardless of test chemical, a decrease or an increase in male brain aromatase activity relative to controls was associated with decreased egg production in cunner and was also correlated with significant changes in GSI in both sexes. E2 and EE2 significantly elevated plasma VTG in males and females, while ATD had no significant effect. Treatment of cunner with OP had no significant effect on any measured endpoint. Overall, results with these exposures indicate EDCs that impact aromatase activity also affect reproductive output in spawning cunner.

Laboratory Spawning Patterns of Mummichogs,Fundulus heteroclitus(Cyprinodontiformes: Fundulidae)

The common estuarine fish species Fundulus heteroclitus or Mummichog has long been used in ecotoxicological studies; however, their periodic spawning pattern is perceived to limit their use in reproductive bioassays and the availability of sensitive life stages. This study evaluated the lunar periodicity of spawning, egg production, and changes in gonadosomatic index (IG) in the laboratory using wild and F1-generation Mummichogs that originated from three different geographic areas: the northern extreme part of their geographic range (New Brunswick, Canada; 45°N), the middle of the northern subspecies range (Massachusetts, USA; 41°N), and within the southern subspecies range (Virginia, USA; 37°N). Unlike some previous studies of wild and laboratory-held fish, Mummichogs from all locations were continuous spawners over a prolonged period of time (8+ weeks) under laboratory conditions. However, there was greater variance in egg production in smaller fish (≤70 mm total length) compared to larger fish. Our re...

Seasonal patterns of gonad size, liver size, and in vitro gonadal steroidogenic capacity in slimy sculpin (Cottus cognatus)

The objective of this study was to characterize the reproductive seasonality of slimy sculpin (Cottus cognatus), a small-bodied, benthic spring spawning species. Sculpin are unique compared with other temperate fish species because they have a reproductive pattern where gonadal maturation occurs over winter in northern areas of its distribution. Previous studies have involved pre-spawning sampling (early spring in North America) and post-spawning sampling (early fall in North America). However, seasonal changes in gonadosomatic index, hepatosomatic index, condition factor, and in vitro gonadal production of estradiol (E2) and testosterone (T) in females and T and 11-ketotestosterone (11-KT) in males have not been characterized. Following a summer quiescent period, female sculpin showed an increase in gonadal hormone production during the fall, which was associated with increases in gonad and liver sizes, however males experienced a much shorter resting phase following spawning in May. Elevated production of both T and 11-KT appears to both signal the initiation of gonadal growth in September and contribute to gonadal maturation over the winter. This study is important because it is the first characterization of the seasonal reproductive pattern in sculpin and it describes the patterns of gonad development and seasonal changes in condition and liver size in this species as it prepares for spawning.