Herve Migaud
University of Stirling, Institute of Aquaculture, Faculty Member
Abstract This study was designed to determine the effects of the selection for body weight and of two final warming durations during an out-of-season reproductive cycle on gonad recrudescence, plasma steroid levels and spawning in... more
Abstract This study was designed to determine the effects of the selection for body weight and of two final warming durations during an out-of-season reproductive cycle on gonad recrudescence, plasma steroid levels and spawning in Eurasian perch Perca fluviatilis males and females. Two different bodyweight classes (200–250 and 350–400 g) and two different warming periods (1 or 2 months) were studied.
Abstract Morphological skin colour change in fish is often referred to in the sole context of background adaptation. It is becoming increasingly apparent that it is a broad phenomenon elicited by a variety of factors. To date, no review... more
Abstract Morphological skin colour change in fish is often referred to in the sole context of background adaptation. It is becoming increasingly apparent that it is a broad phenomenon elicited by a variety of factors. To date, no review has attempted to integrate the different types of morphological colour changes occurring in teleosts, their ecological origins and the regulatory mechanisms involved, often restricting the view on the subject.
Abstract Photoperiod enhancement of growth is becoming an area of increasing interest as a means of enhancing rainbow trout production efficiency in commercial practice. This paper examines the possible implications of shortening periods... more
Abstract Photoperiod enhancement of growth is becoming an area of increasing interest as a means of enhancing rainbow trout production efficiency in commercial practice. This paper examines the possible implications of shortening periods of constant light (LL) exposure on rainbow trout growth during autumn–spring grow-out under ambient water temperatures in freshwater to portion size. Triplicate groups of juvenile all-female rainbow trout were permanently exposed to LL in October, November, December or January.
Page 1. Pilot Project To Acquire And Secure New Technical Capability To Produce All-Female Juvenile Halibut In Scotland SARF027A Dr. H. Migaud Institute of Aquaculture, University of Stirling A REPORT COMMISSIONED BY SARF AND PREPARED BY... more
Page 1. Pilot Project To Acquire And Secure New Technical Capability To Produce All-Female Juvenile Halibut In Scotland SARF027A Dr. H. Migaud Institute of Aquaculture, University of Stirling A REPORT COMMISSIONED BY SARF AND PREPARED BY Page 2. Published by the: Scottish Aquaculture Research Forum (SARF) This report is available at: http://www.sarf.org.uk Dissemination Statement This publication may be re-used free of charge in any format or medium.
Abstract 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... more
Abstract 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.
It is widely held that the development of the circadian system during embryogenesis is important for future survival of an organism. Work in teleosts has been, to date, limited to zebrafish, which provides little insight into the... more
It is widely held that the development of the circadian system during embryogenesis is important for future survival of an organism. Work in teleosts has been, to date, limited to zebrafish, which provides little insight into the diversity of this system within such a large vertebrate class. In this study, the authors analyzed the diel expression of per1, clock, and aanat2 in unfertilized rainbow trout oocytes and embryos maintained under either a 12: 12-h light: dark (LD) cycle or continuous illumination (LL) from fertilization.
The aim of this work was to confirm previous findings suggesting that the eyes are required for night-time melatonin production in Nile tilapia and further characterise this divergent circadian organisation. To do so, melatonin levels... more
The aim of this work was to confirm previous findings suggesting that the eyes are required for night-time melatonin production in Nile tilapia and further characterise this divergent circadian organisation. To do so, melatonin levels were firstly measured in eyecups and plasma to determine circadian patterns of melatonin production. Secondly, the effect of partial ophthalmectomy on the suppression of melatonin production was determined in vivo as well as ex vivo pineal light/dark sensitivity.
L'enrichissement excessif des eaux marines côtières par les sels nutritifs et l'eutrophisation est un problème qui préoccupe de plus en plus Scientifiques, Administrations, Collectivités locales et Professionnels de la mer. Jusqu'à... more
L'enrichissement excessif des eaux marines côtières par les sels nutritifs et l'eutrophisation est un problème qui préoccupe de plus en plus Scientifiques, Administrations, Collectivités locales et Professionnels de la mer. Jusqu'à présent, le suivi des nutriments sur le littoral n'était réalisé qu'épisodiquement par l'intermédiaire du RNO (Réseau National d'Observation) ou du RNC (Réseau National de Contrôle).
In Scotland and elsewhere, there are concerns that escaped farmed Atlantic salmon (Salmo salar L.) may impact on wild salmon stocks. Potential detrimental effects could arise through disease spread, competition, or inter-breeding. We... more
In Scotland and elsewhere, there are concerns that escaped farmed Atlantic salmon (Salmo salar L.) may impact on wild salmon stocks. Potential detrimental effects could arise through disease spread, competition, or inter-breeding. We investigated whether there is evidence of a direct effect of recorded salmon escape events on wild stocks in Scotland using anglers' counts of caught salmon (classified as wild or farmed) and sea trout (Salmo trutta L.).
Behavioral rhythms of the Nile tilapia were investigated to better characterize its circadian system. To do so, the locomotor activity patterns of both male and female tilapia reared under a 12: 12 h light-dark (LD) cycle were studied, as... more
Behavioral rhythms of the Nile tilapia were investigated to better characterize its circadian system. To do so, the locomotor activity patterns of both male and female tilapia reared under a 12: 12 h light-dark (LD) cycle were studied, as well as in males the existence of endogenous rhythmicity under free-running conditions (DD and 45 min LD pulses). When exposed to an LD cycle, the daily pattern of activity differed between individuals: some fish were diurnal, some nocturnal, and a few displayed an arrhythmic pattern.
In homeothermic vertebrates inhabiting temperate latitudes, it is clear that the seasonal changes in daylength are decoded by the master circadian clock, which through secondary messengers (like pineal melatonin secretion) entrains... more
In homeothermic vertebrates inhabiting temperate latitudes, it is clear that the seasonal changes in daylength are decoded by the master circadian clock, which through secondary messengers (like pineal melatonin secretion) entrains rhythmic physiology to local conditions. In contrast, the entrainment and neuroendocrine regulation of rhythmic physiology in temperate teleosts is not as clear, primarily due to the lack of understanding of the clock gene system in these species.
The aim of this study was to compare the efficiency of new candidate lighting-technologies (50W 'blue'light-emitting-diode (B, λmax= 465nm); 232W 'green'hot cathode,(G, λmax= 546nm); 400W 'red'tungsten-halogen,(R, λmax= 667–740nm))... more
The aim of this study was to compare the efficiency of new candidate lighting-technologies (50W 'blue'light-emitting-diode (B, λmax= 465nm); 232W 'green'hot cathode,(G, λmax= 546nm); 400W 'red'tungsten-halogen,(R, λmax= 667–740nm)) against a standard 400W 'white'metal-halide used as control technology (C, broad spectrum) at suppressing sexual maturation of 1+ Atlantic salmon (Salmo salar) in sea-cages.
Abstract: The aim of this study was to compare the circadian control of melatonin production in teleosts. To do so, the effects of ophthalmectomy on circulating melatonin rhythms were studied along with ex vivo pineal culture in six... more
Abstract: The aim of this study was to compare the circadian control of melatonin production in teleosts. To do so, the effects of ophthalmectomy on circulating melatonin rhythms were studied along with ex vivo pineal culture in six different teleosts. Results strongly suggested that the circadian control of melatonin production could have dramatically changed with at least three different systems being present in teleosts when one considers the photic regulation of pineal melatonin production.
Abstract High-intensity constant lighting is routinely used for photoperiod manipulation in the aquaculture industry in order to prevent early maturation. The potential welfare impacts of this technology, however, have not been... more
Abstract High-intensity constant lighting is routinely used for photoperiod manipulation in the aquaculture industry in order to prevent early maturation. The potential welfare impacts of this technology, however, have not been extensively studied to date, and with the implementation of more efficient narrow bandwidth lighting technologies (cathode, light-emitting diodes), definitions of species-specific sensitivities are becoming essential.
The purpose of this work was to investigate the circadian melatonin system in two tropical teleost species characterized by different behavioral habits, Nile tilapia (diurnal) and African catfish (nocturnal). To do so, fish were subjected... more
The purpose of this work was to investigate the circadian melatonin system in two tropical teleost species characterized by different behavioral habits, Nile tilapia (diurnal) and African catfish (nocturnal). To do so, fish were subjected to either a control photoperiod (12L: 12D), continuous light (LL) or darkness (DD), or a 6L: 6D photoperiod. Under 12L: 12D, plasma melatonin levels were typically low during the photophase and high during the scotophase in both species.
Melatonin is a much conserved feature in vertebrates that plays a central role in the entrainment of daily and annual physiological rhythms. Investigations aiming at understanding how melatonin mediates the effects of photoperiod on... more
Melatonin is a much conserved feature in vertebrates that plays a central role in the entrainment of daily and annual physiological rhythms. Investigations aiming at understanding how melatonin mediates the effects of photoperiod on crucial functions and behaviors have been very active in the last decades, particularly in mammals. In fish a clear-cut picture is still missing.
The Kiss1/GPR54 system has recently been shown to play a key role in the onset of puberty in mammals. Growing evidence suggests that this system is also conserved across vertebrates although very few studies so far have been performed in... more
The Kiss1/GPR54 system has recently been shown to play a key role in the onset of puberty in mammals. Growing evidence suggests that this system is also conserved across vertebrates although very few studies so far have been performed in lower vertebrates.
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... more
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.
To date, the trout industry in general has not adopted photoperiod techniques for production enhancement. Extensive research over the last seven years at Stirling has shown the potential benefits of such regimes. This article summarises... more
To date, the trout industry in general has not adopted photoperiod techniques for production enhancement. Extensive research over the last seven years at Stirling has shown the potential benefits of such regimes. This article summarises previous and ongoing research determining how artificial photoperiod regimes can be used to manipulate reproduction and growth for the benefit of the trout industry.