Growth of Arctic charr (Salvelinus alpinus L.) under conditions of constant light and temperature

Seasonal changes in food consumption and growth of Arctic charr exposed to either simulated natural or a 12:12 LD photoperiod at constant water temperature

“…Our observations are consistent with the existence of spontaneously generated circannual cycles of food consumption and growth under constant photoperiod (12 : 12 LD) conditions. These results are in accordance with previous findings for several salmonid species (Brown, 1946;Villarreal et al, 1988;Pálsson et al, 1992), although Jobling (1987) reported a 6-monthly cycle of feeding and growth in Arctic charr held under continuous light conditions at a constant temperature of 10 C. Thus, the results of these different investigations may indicate that there is one or several endogenous rhythms involved in the seasonal control of food consumption and growth in the Arctic charr. The feed intake and growth cycles of the immature charr held under 12 : 12 LD did not differ significantly from those of the immature fish exposed to nLD (Figs 4 and 5), nor did they seem to deviate significantly from 12-monthly cycles, as might have been expected if the rhythms were truly free-running (Gwinner, 1981).…”

Seasonal changes in food consumption and growth of Arctic charr exposed to either simulated natural or a 12:12 LD photoperiod at constant water temperature

“…Our observations are consistent with the existence of spontaneously generated circannual cycles of food consumption and growth under constant photoperiod (12 : 12 LD) conditions. These results are in accordance with previous findings for several salmonid species (Brown, 1946;Villarreal et al, 1988;Pálsson et al, 1992), although Jobling (1987) reported a 6-monthly cycle of feeding and growth in Arctic charr held under continuous light conditions at a constant temperature of 10 C. Thus, the results of these different investigations may indicate that there is one or several endogenous rhythms involved in the seasonal control of food consumption and growth in the Arctic charr. The feed intake and growth cycles of the immature charr held under 12 : 12 LD did not differ significantly from those of the immature fish exposed to nLD (Figs 4 and 5), nor did they seem to deviate significantly from 12-monthly cycles, as might have been expected if the rhythms were truly free-running (Gwinner, 1981).…”

A temperature-dependent growth model for the three-spined stickleback Gasterosteus aculeatus

“…The results on growth rates from contrasting seasons strongly suggest that G. aculeatus exhibits patterns of seasonal growth independent of both photoperiod and temperature, with substantially lowered growth rates during the winter compared to the summer period. Corresponding results have been obtained for other species and it was concluded that seasonal patterns of growth and metabolism can be governed by an endogenous rhythm, independent of cues from the ambient environment (Eriksson & Lundqvist, 1982;Jobling, 1987;Pálsson et al, 1992). The similar patterns shown here for G. aculeatus, with lower growth rates in winter, indicate that caution should be exerted when interpreting and comparing results from growth studies conducted under different seasons.…”

Cyclic growth and activity of pancreatic enzymes in alevins of Arctic charr (Salvelinus alpinus L.)

“…The digestive enzyme secretion patterns can further explain the links between growth rhythms and hormonal cycles. Growth and feed conversion were also significantly correlated both in Jobling's (1987) study on Arctic charr juveniles and in the present one. The clear indication of a cyclic pattern in pancreatic enzyme production is the amylase activity [ Fig.…”

Seasonal changes in food consumption and growth of Arctic charr exposed to either simulated natural or a 12:12 LD photoperiod at constant water temperature

“…Our observations are consistent with the existence of spontaneously generated circannual cycles of food consumption and growth under constant photoperiod (12 : 12 LD) conditions. These results are in accordance with previous findings for several salmonid species (Brown, 1946;Villarreal et al, 1988;Pálsson et al, 1992), although Jobling (1987) reported a 6-monthly cycle of feeding and growth in Arctic charr held under continuous light conditions at a constant temperature of 10 C. Thus, the results of these different investigations may indicate that there is one or several endogenous rhythms involved in the seasonal control of food consumption and growth in the Arctic charr. The feed intake and growth cycles of the immature charr held under 12 : 12 LD did not differ significantly from those of the immature fish exposed to nLD (Figs 4 and 5), nor did they seem to deviate significantly from 12-monthly cycles, as might have been expected if the rhythms were truly free-running (Gwinner, 1981).…”

A temperature-dependent growth model for the three-spined stickleback Gasterosteus aculeatus

“…The results on growth rates from contrasting seasons strongly suggest that G. aculeatus exhibits patterns of seasonal growth independent of both photoperiod and temperature, with substantially lowered growth rates during the winter compared to the summer period. Corresponding results have been obtained for other species and it was concluded that seasonal patterns of growth and metabolism can be governed by an endogenous rhythm, independent of cues from the ambient environment (Eriksson & Lundqvist, 1982;Jobling, 1987;Pálsson et al, 1992). The similar patterns shown here for G. aculeatus, with lower growth rates in winter, indicate that caution should be exerted when interpreting and comparing results from growth studies conducted under different seasons.…”

Cyclic growth and activity of pancreatic enzymes in alevins of Arctic charr (Salvelinus alpinus L.)

“…The digestive enzyme secretion patterns can further explain the links between growth rhythms and hormonal cycles. Growth and feed conversion were also significantly correlated both in Jobling's (1987) study on Arctic charr juveniles and in the present one. The clear indication of a cyclic pattern in pancreatic enzyme production is the amylase activity [ Fig.…”

Seasonal changes in food consumption and growth of Arctic charr exposed to either simulated natural or a 12:12 LD photoperiod at constant water temperature

“…Our observations are consistent with the existence of spontaneously generated circannual cycles of food consumption and growth under constant photoperiod (12 : 12 LD) conditions. These results are in accordance with previous findings for several salmonid species (Brown, 1946;Villarreal et al, 1988;Pálsson et al, 1992), although Jobling (1987) reported a 6-monthly cycle of feeding and growth in Arctic charr held under continuous light conditions at a constant temperature of 10 C. Thus, the results of these different investigations may indicate that there is one or several endogenous rhythms involved in the seasonal control of food consumption and growth in the Arctic charr. The feed intake and growth cycles of the immature charr held under 12 : 12 LD did not differ significantly from those of the immature fish exposed to nLD (Figs 4 and 5), nor did they seem to deviate significantly from 12-monthly cycles, as might have been expected if the rhythms were truly free-running (Gwinner, 1981).…”

A temperature-dependent growth model for the three-spined stickleback Gasterosteus aculeatus

“…The results on growth rates from contrasting seasons strongly suggest that G. aculeatus exhibits patterns of seasonal growth independent of both photoperiod and temperature, with substantially lowered growth rates during the winter compared to the summer period. Corresponding results have been obtained for other species and it was concluded that seasonal patterns of growth and metabolism can be governed by an endogenous rhythm, independent of cues from the ambient environment (Eriksson & Lundqvist, 1982;Jobling, 1987;Pálsson et al, 1992). The similar patterns shown here for G. aculeatus, with lower growth rates in winter, indicate that caution should be exerted when interpreting and comparing results from growth studies conducted under different seasons.…”

Cyclic growth and activity of pancreatic enzymes in alevins of Arctic charr (Salvelinus alpinus L.)

“…The digestive enzyme secretion patterns can further explain the links between growth rhythms and hormonal cycles. Growth and feed conversion were also significantly correlated both in Jobling's (1987) study on Arctic charr juveniles and in the present one. The clear indication of a cyclic pattern in pancreatic enzyme production is the amylase activity [ Fig.…”