Plasma concentrations of steroid hormones in male yellow perch, Perca flavescens: the effect of age and photothermal manipulation (original) (raw)
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Journal of the World Aquaculture Society, 1997
The involvement of photoperiod and temperature in the regulation of reproductive processes was investigated in female yellow perch. Initially, all fish kept indoors were exposed to the same water temperature (22" C) and photoperiod (15L:9D). By the end of August, following the first sampling, fish were submitted to different photothermal regimes. Group A, was maintained under photothermal conditions characteristic for southern Ohio. Group B, was submitted to a condensed lighfftemperature regime designed to accelerate photothermal changes. The mean gonadosomatic index in group A, gradually increased throughout the experiment. Gonadosomatic index in group A, was higher than that in group B, from February through April. The highest plasma concentrations of estradiol in group A, occurred in November and December and exceeded those in group B,. Plasma concentrations of testosterone in group A, were highest in December and tended to be higher in October and April than in other months. There was no difference in plasma testosterone between groups A, and B, except in March when concentrations of this androgen were extremely high in group B,. Ovulation occurred earlier in B regime fish in comparison to that of A regime fish. However, egg quality of fish from regime B was lower than that of fish from regime A. We conclude that the condensed photothermal cycle is not an entirely effective method of inducing out-of-season spawning in female yellow perch. These data suggest that although the compression of the photothermal cycle slightly accelerated spawning, it also caused disturbances in patterns and levels of plasma steroids, diminished ovarian and hepatic growth, and reduced the quality of eggs. Thus, temperature and/or photoperiod may have only a modifying effect on the onset of perch spawning, hut these environmental cues seem to markedly influence earlier stages of gonadal growth and development.
Reproductive physiology of yellow perch (Perca flavescens): environmental and endocrinological cues
Journal of Applied Ichthyology, 1996
An understanding of the mechanisms involved in the regulation of reproductive processes in yellow perch is fundamental for intensive culture of this commercially important, freshwater, perciform fish. This paper describes the annual reproductive cycle of female and male perch. It presents the current state of knowledge on the regulation of ovarian steroidogenesis, final maturation of oocytes and ovulation in this species. Moreover. data concerning biochemistry of spermatozoa and seminal plasma as well as testicular steroidogenesis are summarized. In addition to endocrinological factors, the involvement of environmental (photoperiod and temperature) cues in the regulation of yellow perch reproduction is rcvicwcd. Finally, practical aspccts of controlling perch reproduction are outlined.
Influence of photoperiod on the onset of gonadogenesis in Eurasian perch< i> Perca fluviatilis
2004
The aim of the study was to improve our knowledge on the environmental control of Eurasian perch, Perca fluviatilis, reproductive cycle and determine the effects of photoperiod regimes on the onset of gonadogenesis. Under ambient thermal conditions, three photoperiodic regimes were tested in triplicate: a continuous photophase (24L/0D), a constant photoperiod (16L/8D) and a natural photoperiod. The gonadosomatic index (IG) was calculated and plasma estradiol (E2) and testosterone (T) levels were measured.
Influence of photoperiod regimes on the Eurasian perch gonadogenesis and spawning
Fish Physiology and Biochemistry, 2000
The effects of photoperiod regimes under ambient temperature on gonadal growth and spawning were investigated in Eurasian perch, Perca fluviatilis. This study showed that continuous lighting inhibited reproduction in male and female fish with very low sex steroid levels being measured. Constant LD 16:8 resulted in heterogeneous gonad development and sex steroid levels compared to natural regime, with only 54% of females and < 30% of males maturing. Seasonal variations in daylength also seem to be required to control reproduction.
Reproductive Cycle and Plasma Sex Steroid Profiles in Male Eurasian Perch Perca Fluviatilis
Aquatic Living …, 2000
From April 1995 to April 1996, the annual reproductive cycle of male Eurasian perch Perca fluviatilis was studied at the Lindre Center (Moselle, France). At monthly intervals, five males (mean body weight of 133 ± 43 g and total length of 175 ± 9 mm) were caught. From sampled organs, the gonadosomatic (GSI), hepatosomatic (HSI) and viscerosomatic indexes (VSI) were calculated and plasma testosterone (T) and 11-ketotestosterone (11KT) levels were measured. After the spawning period in mid-April, GSI and HSI dropped and VSI increased to 3.8 ± 0.1 %. In September, GSI reached its maximum (8.5 ± 1.8 %). At this time, spermatocytes, spermatids and spermatozoa were abundant, whereas in June only spermatogonia were observed. During winter, GSI was stable at approximately 5 %, HSI reached its maximum (1.9 ± 0.3 %) and VSI was low (2.6 ± 0.2 %). From April to November 1995, plasma T and 11KT concentrations were low (< 0.5 ng·mL -1 ). Plasma T levels increased significantly in December and reached peak levels (12.3 ± 2.
Aquaculture, 2002
This study was designed to determine the influence of different thermal conditions during an out-of-season reproductive cycle on gonad recrudescence, plasma steroid levels (testosterone and estradiol), vitellogenin (VTG) concentrations and spawning in Eurasian perch (Perca fluviatilis) females. The experiment was performed in 450-l square polyester indoor tanks located in two rooms equipped with controlled light and temperature devices. Four thermal regimes were tested with two different rates of cooling from 21 to 6°C, 3 weeks (3w) or 6 weeks (6w), and two different durations at 6°C, 3 months (3m) or 5 months (5m). The photoperiod was fixed at LD 12:12. A long cooling period (6w) resulted in greater gonadosomatic index (GSI) (3.6 F 0.5%) correlated with a larger oocyte diameter (787.9 F 25.1 mm). The plasma levels of testosterone (13.63 F 1.18 ng ml À 1 ) in the former groups were higher than in the short cooling period groups (6.82 F 0.9 ng ml À 1 ). A longer duration at 6°C (5m) resulted in higher GSI (14.8 F 1%), plasma testosterone levels (26.2 F 0.4 ng ml À 1 ) and plasma protein phosphorus (PPP, 1.33 F 0.3 mg ml À 1 ). The fish from the 6w 5m batch showed the highest plasma estradiol and testosterone levels, whereas the 3w 5m group showed the largest GSI. At the end of the experiment, several spontaneous out-of-season spawnings were collected in batch 6w 5m. Biopsy showed that most oocytes from groups 3w 5m and 6w 5m females were mature (migration of the germinal vesicle 0044-8486/02/$ -see front matter D 2002 Elsevier Science B.V. All rights reserved. PII: S 0 0 4 4 -8 4 8 6 ( 0 1 ) 0 0 6 7 5 -5 (P. Fontaine), patrick.kestemont@fundp.ac.be (P. Kestemont).
Aquaculture, 2002
This study was designed to determine the influence of different thermal conditions during an out-of-season reproductive cycle on gonad recrudescence, plasma steroid levels (testosterone and estradiol), vitellogenin (VTG) concentrations and spawning in Eurasian perch (Perca fluviatilis) females. The experiment was performed in 450-l square polyester indoor tanks located in two rooms equipped with controlled light and temperature devices. Four thermal regimes were tested with two different rates of cooling from 21 to 6°C, 3 weeks (3w) or 6 weeks (6w), and two different durations at 6°C, 3 months (3m) or 5 months (5m). The photoperiod was fixed at LD 12:12. A long cooling period (6w) resulted in greater gonadosomatic index (GSI) (3.6 F 0.5%) correlated with a larger oocyte diameter (787.9 F 25.1 mm). The plasma levels of testosterone (13.63 F 1.18 ng ml À 1) in the former groups were higher than in the short cooling period groups (6.82 F 0.9 ng ml À 1). A longer duration at 6°C (5m) resulted in higher GSI (14.8 F 1%), plasma testosterone levels (26.2 F 0.4 ng ml À 1) and plasma protein phosphorus (PPP, 1.33 F 0.3 mg ml À 1). The fish from the 6w 5m batch showed the highest plasma estradiol and testosterone levels, whereas the 3w 5m group showed the largest GSI. At the end of the experiment, several spontaneous out-of-season spawnings were collected in batch 6w 5m. Biopsy showed that most oocytes from groups 3w 5m and 6w 5m females were mature (migration of the germinal vesicle
Fish Physiology and Biochemistry - FISH PHYSIOL BIOCHEM, 2002
This study examined the changes in plasma steroids during natural (Experiment 1) and induced (Experiment 2) final maturation in yellow perch Perca flavescens. In experiment 1, ovulating yellow perch were stripped of eggs and blood samples collected to determine the concentrations of testosterone (T), estradiol-17β (E2), and 17,20β-dihydroxy-4-pregnen-3-one (17,20βP). Eggs from individual females were weighed and fertilized. Fertilization rate was determined at the embryo eyed stage. In experiment 2, females were randomly assigned to one of the following treatment groups: (1) saline (0.7% NaCl), (2) des-Gly10[D-Ala6] LHRH-ethylamide (100 μg LHRHa/kg), and (3) LHRHa plus 17,20βP (100 μg LHRHa/kg + 2 mg 17,20βP/kg). Fish were injected intraperitoneally with two doses at a two-day interval. Blood was collected prior to injections and at the time of ovulation/spawning and concentrations of T, E2, and 17,20βP (free and conjugated) were determined. In experiment 1, low concentrations of 17...
Aquaculture, 2006
In Eurasian perch, Perca fluviatilis, gametogenesis is induced by decrease of both temperature and photoperiod. However, a multiplicity of other factors can display non-permissive or modulating effects on the induction of the reproductive cycle. Consequently, a 9-week study was carried out to determine the environmental cues and permissive factors controlling the induction of the reproductive cycle in this species. A two-level fractional factorial design 2 8-4 was used in order to identify the influent factors from 8 environmental and nutritional ones and their 28 interactions. Tested factors were: (1) amplitude of temperature decrease, (2) time, (3) kinetics and (4) amplitude of photoperiod decrease, (5) initial nutritional state, (6) handling, (7) feeding rate and (8) light spectrum. Increase of gonadosomatic index (GSIi), proportion of female in exogenous vitellogenesis (EVP), plasma 17 β-estradiol (E 2) and cortisol levels, fat consumption and food intake were evaluated. This study showed that the amplitude of the decrease of temperature and the time of photoperiod decrease are the two main environmental cues controlling the induction of the reproductive cycle in Eurasian perch. GSIi was the highest (3.8%) when females were exposed to both low amplitude of temperature decrease and precocious decrease of photophase. It was the lowest (1.1%) when high amplitude of temperature decrease and late decrease of photophase were applied. Handling in association with temperature modulated the broodstock response. 100% of the unhandled fish held at 14°C were at the exogenous vitellogenesis stage with mean E 2 and basal cortisol levels of 1.6 ng mL − 1 and 9 ng mL − 1 respectively. Handled fish and fish held at 6°C exhibited lower vitellogenesis (40-73%) associated with lower E 2 (0.6-1.1 ng mL − 1) and higher basal cortisol levels (37-89 ng mL − 1). No other factor nor interaction displayed a cueing or non permissive effect on the induction of the reproductive cycle in female Eurasian perch. A first schematic model is proposed to explain the factorial determinism of the induction of the reproductive cycle.
Influence of photoperiod on the onset of gonadogenesis in Eurasian perch Perca fluviatilis
Aquaculture, 2004
The aim of the study was to improve our knowledge on the environmental control of Eurasian perch, Perca fluviatilis, reproductive cycle and determine the effects of photoperiod regimes on the onset of gonadogenesis. Under ambient thermal conditions, three photoperiodic regimes were tested in triplicate: a continuous photophase (24L/0D), a constant photoperiod (16L/8D) and a natural photoperiod. The gonadosomatic index (I G ) was calculated and plasma estradiol (E 2 ) and testosterone (T) levels were measured. This study showed that a 24-h photophase, applied to fish from mid-July to the beginning of October, inhibits the initiation of gametogenesis (I G below 2% and 1% in females and males, respectively). A constant photoperiod (16L/8D) resulted in a very heterogeneous gonadal development. Twenty percent of females and 40% of males developed their gonads and mean I G reached lower values than in females and males from the natural photoperiod. In the natural photoperiod treatment, gonadal development in all fish was comparable to that of fish observed in natural habitat at the same period of the year (I G above 3%). Seasonal variations in 0044-8486/$ -see front matter D daylength seem to be involved in the initiation of gametogenesis in perch, whereas continuous photophase inhibits gonadal development. Photoperiodic variations play a crucial role in the initiation of perch reproduction. D