The role of seasonally altering photoperiod in regulating physiology in Atlantic cod (Gadus morhua). Part II. Somatic growth

摘要: Research to date has not clearly defined the role of photoperiod in regulating somatic growth Atlantic cod (Gadus morhua). The present study followed individual performance, plasma insulin-like factor-I, and relative liver size response a range experimental treatments where populations were transferred from an ambient regime continuous illumination at strategic times during first 2 years life. While this work demonstrated that application could directly stimulate growth, stimulation is transitory with no accumulative effect prolonged exposure illumination. Importantly, it was apparent photic inhibition maturation realized far more significant stimulation, popula- tions occurred, sexually dimorphic patterns became apparent. Plasma factor-I displays seasonal rhythm correlated temperature under natural conditions certain circum- stances be used as accurate predictor rate. Overall, further refines guidelines on management commercial ongrowing species help realize maximum economic potential aquaculture. Resume : Les travaux de recherche menes jusqu'a ce jour n'ont pas permis definir clairement le joue par la photoperiode dans regulation croissance somatique chez morue Atlantique Durant notre etude, nous avons fait un suivi individuel des performances croissance, analyse les teneurs plasmatiques en facteur 1 type insulinique et mesure l'indice hepato-somatique reponse une variete traitements experi- mentaux photoperiodiques consistant transferer morue, temps precis, d'un photo- periode naturelle vers eclairement continu durant leurs premieres annees vie. Notre etude demontre que, meme si periodes lumiere continue peuvent stimuler directement cette n'est que transitoire n'augmente proportionnellement duree d'exposition l'eclairement continu. Il est important noter l'inhibition du cycle reproduction permet bien plus importante. De plus, ces restees immatures, observe dimorphisme sexuel croissance. existe rythme saisonnier correle fois aux variations l'eau naturelles d'eclairement et, certains cas, taux poissons. D'une facon globale, nos ont determiner avec precision regimes appliquer pendant phase grossissement l'industrie pisciculture pour ameliorer rendement.