Growth Of Arctic Charr Research Articles

Assessing the growth of Arctic charr (Salvelinus alpinus) (Linnaeus, 1758) in four salinities, under experimental conditions.

Studies in Salvelinus alpinus, Arctic charr, indicate that it has a low capacity to hyposmorregulatory or adaption to sea in winter periods in Arctic waters. The investigation finds to determinate the rank optimum of salinity to can cultivate this species at Chile. The weight adequate was determined to join on the sea by analysis of gill Na+, K+-ATPase activity, that it was found between the ranks 80-130 g, with 14.5 U/mg. It underwent evaluation of fish growth of 72 g salinities from 0 (control), 18, 25 and 33 g/L (sea water) for 94 days. The results indicate that the largest increases were obtained in brackish water. T18 g/L and T25 g/L achieved growth of 25% and 19% on day 94 and term sampling respectively. It is important to mention that the 8% that survived in seawater introduced percentages growth 16.6% equivalent to brackish water and control. These results suggest that Salvelinus alpinus can grow in seawater, with levels of Na+, K+-ATPase similar to those submitted by Salmo salar with a weight not less than 80 g.

Parental effects on embryonic viability and growth in Arctic charrSalvelinus alpinusat two incubation temperatures

The parental influences on three progeny traits (survival to eyed-embryo stage, post-hatching body length and yolk-sac volume) of Arctic charr Salvelinus alpinus were studied under two thermal conditions (2 and 7 degrees C) using a factorial mating design. The higher temperature resulted in elevated mortality rates and less advanced development at hatching. Survival was mostly attributable to maternal effects at both temperatures, but the variation among families was dependent on egg size only at the low temperature. No additive genetic variation (or pure sire effect) could be observed, whereas the non-additive genetic effects (parental combination) contributed to offspring viability at 2 degrees C. In contrast, any observable genetic variance in survival was lost at 7 degrees C, most likely due to the increased environmental variance. Irrespective of temperature, dam and sire-dam interaction contributed significantly to the phenotypic variation in both larval length and yolk size. A significant proportion of the variation in larval length was also due to the sire effect at 2 degrees C. Maternal effects were mediated partly through egg size, but as a whole, they decreased in importance at the high temperature, enabling a concomitant increase in non-additive genetic effects. For larval length, however, the additive component, like maternal effects, decreased at 7 degrees C. The present results suggest that an exposure to thermal stress during incubation can modify the genetic architecture of early developmental traits in S. alpinus and presumably constrain their short-term adaptive potential and evolvability by increasing the amount of environmentally induced variation.

Intraspecific competition and density dependence of food consumption and growth in Arctic charr

1. Intraspecific competition for restricted food resources is considered to play a fundamental part in density dependence of somatic growth and other population characteristics, but studies simultaneously addressing the interrelationships between population density, food acquisition and somatic growth have been missing. 2. We explored the food consumption and individual growth rates of Arctic charr Salvelinus alpinus in a long-term survey following a large-scale density manipulation experiment in a subarctic lake. 3. Prior to the initiation of the experiment, the population density was high and the somatic growth rates low, revealing a severely overcrowded and stunted fish population. 4. During the 6-year period of stock depletion the population density of Arctic charr was reduced with about 75%, resulting in an almost twofold increase in food consumption rates and enhanced individual growth rates of the fish. 5. Over the decade following the density manipulation experiment, the population density gradually rose to intermediate levels, accompanied by corresponding reductions in food consumption and somatic growth rates. 6. The study revealed negative relationships with population density for both food consumption and individual growth rates, reflecting a strong positive correlation between quantitative food intake and somatic growth rates. 7. Both the growth and consumption rate relationships with population density were well described by negative power curves, suggesting that large density perturbations are necessary to induce improved feeding conditions and growth rates in stunted fish populations. 8. The findings demonstrate that quantitative food consumption represents the connective link between population density and individual growth rates, apparently being highly influenced by intraspecific competition for limited resources.

Inter-annual growth of Arctic charr (Salvelinus alpinus, L.) in relation to climate variation

BackgroundMajor changes in climate have been observed in the Arctic and climate models predict further amplification of the enhanced greenhouse effect at high-latitudes leading to increased warming. We propose that warming in the Arctic may affect the annual growth conditions of the cold adapted Arctic charr and that such effects can already be detected retrospectrally using otolith data.ResultsInter-annual growth of the circumpolar Arctic charr (Salvelinus alpinus, L.) was analysed in relation to climatic changes observed in the Arctic during the last two decades. Arctic charr were sampled from six locations at Qeqertarsuaq in West Greenland, where climate data have been recorded since 1990. Two fish populations met the criteria of homogeny and, consequently, only these were used in further analyses. The results demonstrate a complex coupling between annual growth rates and fluctuations in annual mean temperatures and precipitation. Significant changes in temporal patterns of growth were observed between cohorts of 1990 and 2004.ConclusionDifferences in pattern of growth appear to be a consequence of climatic changes over the last two decades and we thereby conclude that climatic affects short term and inter-annual growth as well as influencing long term shifts in age-specific growth patterns in population of Arctic charr.

Growth in Arctic charr and rainbow trout fed temporally concentrated or spaced daily meals

The effect on growth of distributing feed over a few hours compared tomore frequent meals was tested on 1+ Arctic charr (Salvelinus alpinus L.) and 1+ rainbow trout (Oncorhynchus mykiss Walbaum). Triplicate hatchery groups for each treatment were fed at a ration level of 1%/dayeither with few meals (8 times per day divided into morning and evening)or with frequent meals (32 meals equally distributed during the day). Wefound an opposite effect of meal frequency on growth in the two species.Low feeding intensity (8 meals per day) had a significantly positive effecton growth in rainbow trout but a significantly negative effect on growth inArctic charr when compared to feeding the fish frequent meals. Theopposite response to meal frequency is likely to be an effect of thedifferences in activity during feeding. Rainbow trout feed much moreaggressively than charr which can result in feeding being a more stressfulevent. In this experiment, the specific growth rate was lower and the feedconversion ratio higher for Arctic charr compared to rainbow trout.

Vaccination influences growth of Arctic charr.

There is limited knowledge about the effects of oil-based vaccines on the growth of Arctic charr Salvelinus alpinus, in particular at different rearing temperatures. One-year-old Arctic charr were immunized intraperitoneally at 2.9 degrees C with a metabolizable oil-adjuvanted, bivalent vaccine containing killed typical and atypical Aeromonas salmonicida bacteria. After vaccination the non-vaccinated (controls) and vaccinated individually marked fish were held for 20 d at 10.0 degrees C and then for 7 wk at 10.3, 14.1 or 18.1 degrees C. During the first 20 d at 10.0 degrees C the growth rate (G) was higher for non-vaccinated than vaccinated fish. Thereafter vaccinated charr had higher G than control fish at 10.3 and 14.1 degrees C. In contrast, at 18.1 degrees C there was no difference in G and therefore no compensation of earlier growth suppression in vaccinated fish was observed at that temperature. The study indicates that vaccination has no ultimate negative effects on the growth of Arctic charr at temperatures ranging from 10.3 to 14.1 degrees C.

Growth effects in Arctic charr reared in cold water: feed frequency, access to bottom feeding and stocking density.

The effects of time restricted feeding, possibility of bottomfeeding and stocking density on the growth of Arctic charr(Salvelinus alpinus L.) were examined in fish held at lowtemperature ( 0.05) increase in growth rate(0.13 vs 0.12%percnt; per day).

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

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

Influence of maturity status on the annual cycles of feeding and growth in Arctic charr reared at constant temperature

Temporal changes in feeding and growth of immature (1 +), maturing male (1 +), and mature male and female (3+) Arctic charr were studied by monitoring feed intake and growth of individually‐marked fish for over 1 year. The fish were held at a constant temperature (4°C) under conditions of liberal feed supply. Feed intake and growth remained low in the period December‐April, with only 20–60% of the fish having fed on each occasion that feed intake was monitored. Feed intake and growth increased markedly during the late spring and summer, but the increases were delayed by approximately 1–2 months in the immature fish compared with their maturing counterparts. Maturing fish decreased feeding during the late summer and by September there had been an almost complete cessation of feeding. This was reflected in changes in fish body weight and condition, both of which declined from August‐September onwards. By contrast, the immature fish peaked in weight and condition in September, and weight loss during the autumn tended to be less rapid than observed for the maturing fish. The fish appeared to reduce feeding once a‘threshold condition’ of 1–4—1–5 had been attained. It is suggested that the fish may become anorexic once there has been replenishment of the energy reserves required for overwintering and, in the case of maturing individuals, for the completion of gonadal growth and Spawning.

Influence of maturity status on the annual cycles of feeding and growth in Arctic charr reared at constant temperature

Temporal changes in feeding and growth of immature (1 +), maturing male (1 +), and mature male and female (3+) Arctic charr were studied by monitoring feed intake and growth of individually-marked fish for over 1 year. The fish were held at a constant temperature (4°C) under conditions of liberal feed supply. Feed intake and growth remained low in the period December-April, with only 20–60% of the fish having fed on each occasion that feed intake was monitored. Feed intake and growth increased markedly during the late spring and summer, but the increases were delayed by approximately 1–2 months in the immature fish compared with their maturing counterparts. Maturing fish decreased feeding during the late summer and by September there had been an almost complete cessation of feeding. This was reflected in changes in fish body weight and condition, both of which declined from August-September onwards. By contrast, the immature fish peaked in weight and condition in September, and weight loss during the autumn tended to be less rapid than observed for the maturing fish. The fish appeared to reduce feeding once a‘threshold condition’ of 1–4—1–5 had been attained. It is suggested that the fish may become anorexic once there has been replenishment of the energy reserves required for overwintering and, in the case of maturing individuals, for the completion of gonadal growth and Spawning.

Growth and survival of European grayling reared at different stocking densities

In Sweden, many European grayling, Thymallus thymallus, populations have decreased owing to freshwater acidification, water-flow regulation and overfishing. Thus there is an increasing demand for production of grayling for stocking purposes. Knowledge concerning intensive rearing technology for grayling is generally limited to the rearing of one-summer-old fish (Carlstein, 1993), although older grayling have been reared in natural ponds with poor results (L. -0. Eriksson, pers. comm.). There is a paucity of information about the effect of stocking density on the intensive rearing of grayling. Stocking density, i.e. the amount of fish reared per unit volume, is a key factor in fish farming economics because growth, survival and production costs are often strongly influenced by it, Optimal stocking density in intensive rearing operations varies, depending on the rearing methods as well as the species, size and age of the fish. Several studies have been performed to examine the effect of stocking density on the growth of different fish species. There is often a negative relation between density and growth, e.g. in the rearing of juvenile Atlantic salmon,SQlmo sQlQr(Refstie and Kittelsen, 1976), brook charr, Salvelinus fontinalis (Vijayan and Leatherland, 1988, 1989) and rainbow trout, Oncorhynchus mykiss (Refstie, 1977; Trzebiatowski et al., 1981; Papoutsoglou et al., 1987). By contrast, increasing the stocking density can enhance the growth of Arctic charr, Salvelinus alpinus (Brown et al., 1992; Jprrgensen et al., 1993). Baker and Ayles (1990) showed that the growth rate of Arctic charr reared in tanks increased with density, reaching an optimum at 40-60 kg m a. The positive effect of crowding in Arctic char-r probably results from a change in behaviour from agonistic interactions to shoaling as stocking density is increased (Wallace et al., 1988; Baker and Ayles, 1990). The present study was carried out to examine the effect of stocking density on the growth and survival of one-summer-old European grayling under standard hatchery rearing conditions. The study was carried out at the SPna Fish Farm between 8 January and 25 February 1992. The fish used in this experiment were the offspring of adult spawners caught in the River &terdaltilven (see Carlstein, 1993, for further details of rearing). In January 1992, one-summer-old grayling were transferred into twelve 1 m3 (1 m2 X 1 m) standard rearing tanks (EWOS type 2009) to give two replicate of six different initial stocking densities: 5,10,15,20,30 and 50 kg fish m3 (Table 1). These grayling were obtained from

Effects on growth of Arctic charr of handling, anaesthesia and repeated formalin bathing shortly after first exogenous feeding

An experiment was conducted to test whether handling, anaesthesia or repeated formalin bathing had any effect on the growth rate in first feeding Arctic charr held in separate containers. The results show that these treatments had no effect on the growth rate.

Feeding in darkness eliminates density-dependent growth suppression in Arctic charr

KEYWORDS: Arctic charr, Feeding, Growth, Social interactions Growth performance of Arctic charr, Salvelinus alpinus, is depressed at low (<20 kg m ~) stocking densities and growth has been reported to reach a maximum when fish are stocked at densities of 50-70 kg m -3 (Wallace et al., 1988; Baker and Ayles, 1990; Jorgensen et al., 1993). Growth rates may, however, be high when fish are stocked at densities in excess of 100 kg m -3, provided that good water quality can be maintained (Wallace et al., 1988; Jcrgensen et al., 1993). The causes of growth depression of charr stocked at low densities are not known, but it has been suggested that aggressive behaviour, the formation of territories and the establishment of dominance hierarchies may be contributory factors (Jobling and Wandsvik, 1983; Jobling, 1985; Wallace et al., 1988; Brown et al., 1992). In a recent study, however, Jorgensen et aL (1993) did not find evidence that despotism, and the establishment of clear-cut dominance hierarchies, was a major factor contributing to growth suppression of the fish stocked at the lowest density (15 kg m-3). In this latter study, locomotory activity, food intake and growth rates were depressed in all individuals held at low stocking density. Food was offered continuously, and in excess, and, thus, the reasons for the growth suppression in these fish are still not clear. In the present report, data are presented showing that feeding in darkness eliminates the negative effects of low stocking density on growth in Arctic charr. In the current experiment, eight groups of individually tagged (FTF-69 fingerling tags, Floy Tag & Mfg), hatchery-reared Arctic charr with an initial average weight of 28 g were held in 90 1, circular tanks for a period of 44 days. Four groups were held under continuous light conditions and the remaining four under short-day (8L:16D) conditions. For groups held under both light regimes, the numbers of fish in two tanks were 25 and in the other two tanks 100. This corresponded to an initial stocking density of 10 and 36 kg m -3, respectively. All groups were fed in excess for 16 h each day on commercial dry pellets (FK Start, 2.5 mm), using automatic disc feeders. Feeding was carried out during the time of the day in which the short-day groups (8L:16D) experienced darkness. Water temperature was maintained at 8.0 °C. One week after the establishment of the groups (day 7), live weights of individual fish were recorded, and measurements were repeated on day 44. Specific growth rates (SGR, % day -1) were calculated as [(lnWT -- InWt) • 100]" (T - t) -~, where Wt and WT represent fish weights at the start (day 7) and the end of the experiment (day 44), respectively, and T - t represents the number of days between weighings. * Author to whom correspondence should be addressed. 0967-6120 © 1993 Chapman & Hall

Ecology and conservation of arctic charr, Salvelinus alpinus (L.), in Loch Doon, an acidifying loch in Southwest Scotland

Several populations of arctic charr Salvelinus alpinus in southern Scotland have become extinct and Loch Doon is the only site left for the species in the southwest. The catchment of the loch lies mainly on granite and much has recently been afforested. Most of the inflowing streams are acid and the loch itself appears to have acidified over the last two decades. Few acid-sensitive invertebrates occur in the streams or in the loch. The fish populations of the most acid streams are low in density. Growth of arctic charr in the loch resembles that in some other Scottish lochs but appears to have increased in recent years. The charr feed on benthic invertebrates for much of the year but on zooplankton in the summer. Spawning occurs in early October, leaving the fish in poor condition which improves during the spring to reach a maximum in late summer, just prior to spawning. Spawning takes place over gravel and stones in shallow water all round the loch. Angling data indicate that the average size of both trout and arctic charr in Loch Doon has increased significantly over the last 15 years. Chemical and biological evidence suggests that Loch Doon is acidifying and that management is necessary if the stock of charr there is to be saved.

The effects of stocking density on early growth in Arctic charr, Salvelinus alpinus (L.)

Fry of Arctic charr, Salvelinus alpinus (L.), were held at seven different stocking densities during and after the initial feeding period. Stocking density affected growth, the populations held at densities of 25 and 50 fry/l showing significantly slower growth and slightly higher mortality than the populations held at densities of 70–250 fry/l. In similar experiments using fish of initial weight 5.5 g and stocked at densities of 5.3, 15.9 and 37 kg fish/m 3 water, growth rate was observed to be positively correlated with stocking density. Arctic charr of initial weight 16 g grew extremely well after being stocked at an initial density of 110 kg/m 3. It would appear that high population density affects young Arctic charr such that agonistic behaviour is inhibited and schooling behaviour stimulated.

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

Arctic charr, Salvelinus alpinus, display distinct cycles of food intake, growth and conversion when reared in the laboratory under constant conditions (continuous light; temperature 10°C). Growth rates peaked in December–January and June–July and it is suggested that charr may have an endogenous growth rhythm with a 6-month cycle.

Effect of sorting on size-frequency distributions and growth of Arctic charr, Salvelinus alpinus L.

Arctic charr, Salvelinus alpinus, were reared in either unsorted groups or in groups that had been sorted into ‘small’ and ‘large’ fish. At the start of the experiment the size-frequency distributions of unsorted and pooled ‘small’ and ‘large’ fish were similar, but after 5 months' rearing distributions were markedly different. There was evidence that growth of ‘small’ fish improved in the absence of larger conspecifics, but size-sorting also led to reduced growth of some large fish, with the consequence that size-sorting did not lead to overall increases in biomass gain and rates of production.

Physiological and social constraints on growth of Arctic charr, Salvelinus alpinus L.: an investigation of factors leading to stunting

When stunted (runt) Arctic charr, Salvelinus alpinus, were reared together in small groups growth rates were low. Contrary to expectation, there did not arise a rapidly growing despot within each group. It is suggested that the narrow size range offish within groups prevented the rapid formation of clear‐cut dominance hierarchies. Fish reared in isolation had significantly higher and more variable rates of growth than those held in groups, demonstrating that social interactions between individuals were responsible for growth suppression of grouped‐reared fish. There were no significant differences in growth rates between fish allowed visual contact with conspecifics and those held in visual isolation, indicating that visual contact is insufficient to cause growth depensation in Arctic charr. Despite the fact that growth rates of stunted (runt) Arctic charr improved when they were held in isolation, the growth rates recorded were substantially lower than those of normal individuals reared under hatchery conditions. It is concluded that physiological (genetic) factors are important in the determination of the slow growth rates of stunted (runt) Arctic charr and that this trend is exacerbated by social interactions with more rapidly growing siblings.

Observations on growth rates of Arctic charr, Salvelinus alpinus (L.), reared at low temperature

Food intake and growth of Arctic charr, Salvelinus alpinus, in fresh water was studied at three temperatures 2·9, 8·4 and 13·1° C). Best growth and highest food intake occurred at 13·1°C. The approximate chemical composition was dependent upon rearing temperature, fish reared at the highest temperature depositing large quantities of fat. Fish were later grown on in either fresh or salt water where two growth patterns were observed. In the light of published data for Salvelinus spp., it is suggested that the poorest growth was shown by fish which were incapable of complete adaptation to saltwater conditions.