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Appears in Collections:Aquaculture Journal Articles
Peer Review Status: Refereed
Title: The role of seasonally altering photoperiod in regulating physiology in Atlantic cod (Gadus morhua). Part II. Somatic growth
Author(s): Davie, Andrew
Porter, Mark J R
Bromage, Niall R
Migaud, Herve
Porter, Mark J R
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Issue Date: Jan-2007
Date Deposited: 6-May-2014
Citation: Davie A, Porter MJR, Bromage NR, Migaud H & Porter MJR (2007) The role of seasonally altering photoperiod in regulating physiology in Atlantic cod (Gadus morhua). Part II. Somatic growth. Canadian Journal of Fisheries and Aquatic Sciences, 64 (1), pp. 98-112.
Abstract: Research to date has not clearly defined the role of photoperiod in regulating somatic growth in Atlantic cod (Gadus morhua). The present study followed individual growth performance, plasma insulin-like growth factor-I, and relative liver size in response to a range of experimental photoperiod treatments where populations were transferred from an ambient photoperiod regime to continuous illumination at strategic times during the first 2 years of life. While this work demonstrated that application of continuous illumination could directly stimulate somatic growth, this growth stimulation is transitory with no accumulative effect of prolonged exposure to continuous illumination. Importantly, it was apparent that the photic inhibition of maturation realized a far more significant growth stimulation, and in populations where this occurred, sexually dimorphic growth patterns became apparent. Plasma insulin-like growth factor-I displays a seasonal rhythm correlated with ambient temperature under natural photic conditions and in certain circumstances could be used as an accurate predictor of growth rate. Overall, this work further refines the guidelines on photoperiod management during commercial ongrowing of the species to help realize the maximum economic potential of cod aquaculture.Les travaux de recherche men‚s jusqu'a ce jour n'ont pas permis de d‚finir clairement le r“le jou‚ par la photop‚riode dans la r‚gulation de la croissance somatique chez la morue Atlantique (Gadus morhua). Durant notre ‚tude, nous avons fait un suivi individuel des performances de croissance, analys‚ les teneurs plasmatiques en facteur 1 de croissance de type insulinique et mesur‚ l'indice h‚pato-somatique en r‚ponse … une vari‚t‚ de traitements exp‚rimentaux photop‚riodiques consistant … transf‚rer des populations de morue, … des temps pr‚cis, d'un r‚gime de photop‚riode naturelle vers un ‚clairement continu durant leurs 2 premiŠres ann‚es de vie. Notre ‚tude a d‚montr‚ que, mˆme si des p‚riodes de lumiŠre continue peuvent stimuler directement la croissance somatique chez la morue, cette stimulation n'est que transitoire et n'augmente pas proportionnellement … la dur‚e d'exposition … l'‚clairement continu. Il est important de noter que l'inhibition du cycle de reproduction par le r‚gime de lumiŠre permet une stimulation de la croissance bien plus importante. De plus, chez ces populations rest‚es immatures, on observe un dimorphisme sexuel de croissance. Il existe un rythme saisonnier des teneurs plasmatiques en facteur 1 de croissance de type insulinique corr‚l‚ … la fois aux variations de la temp‚rature de l'eau en conditions naturelles d'‚clairement et, dans certains cas, aux taux de croissance des poissons. D'une fa‡on globale, nos travaux ont permis de d‚terminer avec plus de pr‚cision les r‚gimes photop‚riodiques … appliquer pendant la phase de grossissement par l'industrie de la pisciculture de la morue pour am‚liorer le rendement.
DOI Link: 10.1139/f06-170
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