Charr Salvelinus Alpinus Research Articles

Q-band chromosomal polymorphisms in arctic char (Salvelinus alpinus)

Stock-specific variation in the number and location of quinacrine-staining chromosomal bands was found in North American and European stocks of arctic char (Salvelinus alpinus). The mean number of bands per genome varied from 5.8 ± 5.3 in the Northwest Territories stock to 15.4 ± 2.1 in the Scottish stock. These bands appear to represent a subset of heterochromatin since they stain darkly with the C-band technique. Since the four stocks examined were each distinguishable on the basis of their Q-band patterns, these chromosome markers should be useful in genetic comparisons between different arctic char stocks and populations.Key words: Q banding, chromosomes, polymorphisms, arctic char, Salvelinus alpinus.

Growth pattern and maturation in arctic char (Salvelinus alpinus L.) of Lake Walenstadt, Switzerland

Within one decade the yield in arctic char fishery of Lake Walenstadt (Switzerland) has dropped from 1.7 kg · ha−1 to 0.7 kg · ha−1. In the same period growth decreased by about 15%. The fish considered as “degenerated dwarfed chars” by fishermen are supposed to mature in very young ages.

Diel patterns of activity and substrate preference in young Arctic char from the Koroc River, northern Quebec

Young Arctic char (Salvelinus alpinus) were observed in a stream tank located on the bank of the Koroc river, northern Quebec. Early in the summer, char were most active from dusk to dawn, and at midday, mainly over gravel or sand. Some nocturnal feeding activity was evident. As the summer progressed, this diel periodicity in activity became less pronounced; char exhibited increasing diurnal activity, most of it over rubble substrata. Char preferred rubble for resting throughout the summer. Invertebrate drift decreased from July through August so that, although fish were active more of the time, the rate of feeding during periods of activity declined.

Impaired Swimming Performance of Acid-exposed Arctic Charr, Salvelinus Alpinus L.

Abstract Arctic charr (Salvelinus alpinus L.) were exposed to five levels of acidity between pH 6 and pH 3.8. Swimming performance as determined by critical swimming speeds was 67.5 cm · sࢤ1 or 4.4 body lengths per second for untreated fish (pH 7.8). Performance declined sharply below pH 4.5; at pH 3.8 it was reduced by 35% after 7 days of exposure. Tailbeat frequencies and ventilation rates showed no dose-response effects. At swimming speeds between 20 and 50 cm · sࢤ1, ventilation rates at all levels of acidity were higher than at the control level.

Behavioral Alterations in Arctic Char (Salvelinus alpinus) Briefly Exposed to Sublethal Chlorine Levels

Changes in the locomotor behavior of Arctic char (Salvelinus alpinus) exposed inadvertently to sublethal chlorine concentrations (> 19μg total residual chlorine/L) for 6 d are described. Compared with their preexposure behavior, the char became hypoactive, much more strongly thigmotactic, and less responsive to a food extract during the exposure. After the high chlorine levels subsided, the char continued to be hypoactive for at least 1 wk and failed to respond positively to the food extract for 20 d. There is evidence that some individuals displayed chlorine stress behavior for at least 46 d after the return of nonstressful conditions.

Uptake and release of fluoride in arctic char

Fluoride levels were measured in Arctic char (Salvelinus alpinus) living near Narsaq. The Narsaq River is unpolluted, but has naturally high levels of fluoride—varying from about 2 mg/L in summer to 10 to 20 mg/L in winter. The river has a relatively large population of Arctic char which appears unaffected by the high fluoride level. Stationary char accumulate fluoride in muscles (16.6 mg/kg) and bones (1,150 mg/kg), while char caught in the estuary have concentrations similar to char from reference areas (6.5 mg/kg in muscle, 439 mg/kg in bone). It is concluded that Arctic char accumulate fluoride when living in the high-fluoride freshwater environment, but that concentrations return to normal in anadromous char during the 1 to 2 summer months annually spent at sea.

A survey of the parasites of nonanadromous and anadromous brook charr (Salvelinus fontinalis) in the Tabusintac River, New Brunswick, Canada

A parasite survey of 1146 brook charr (Salvelinus fontinalis) was conducted between January 1981 and December 1982 in the Tabusintac River, New Brunswick, Canada. A total of 36 parasite species were recovered, of which 18 (one Myxosporea, two Monogenea, three Digenea, three Cestoidea, five Nematoda, one Acanthocephala, one Hirudinoidea, one Crustacea, and a Dermocystidium sp.) were freshwater and 18 (two Monogenea, seven Digenea, two Cestoidea, two Nematoda, two Acanthocephala, and three Crustacea) were marine. Anadronomous charr were differentiated from nonanadromous charr in fresh water by the presence of marine parasites. Charr in the estuary and lagoon were all considered to be anadromous; however, first-time anadromous charr or smolts were differentiated by the absence of marine parasites and infection with freshwater parasites only. New host records include Lecithaster gibbosus, Zoogonus lasius, Podocotyle angulata, Cryptocotyle lingua (metacercariae), Stephanostomum tenue (metacercariae, adults), Eubothrium crassum, Tetraphyllidea gen. sp. (plerocercoids), Eustrongylides sp. (larvae), Hysterothylacium aduncum (larvae, adults), Corynosoma magdaleni (juveniles), Argulus alosae, and Ergasilus labracis. Zoogonus lasius and Stephanostomum tenue represent new Canadian records, and Chloromyxum truttae and Truttaedacnitis truttae are reported for the first time from New Brunswick. Bulbodacnitis alpinus, previously reported only from the Arctic charr (Salvelinus alpinus), is considered to be a synonym of T. truttae.

Croissance et reproduction de l'omble-chevalier,Salvelinus alpinus (L.), dans le lac de Neuchâtel (Suisse)

The arctic char (Salvelinus alpinus) which has disappeared from Lake Neuchâtel near 1963, has been reintroduced into this lake since 1979. In this study, growth and reproduction of char have been analyzed 4 years after reintroduction.

Heavy Exploitation of a Dense Resident Population of Arctic Char in a Mountain Lake in Central Norway

Abstract During a period of 6 years (1979-1984), heavy exploitation of a dense resident population of Arctic char (Salvelinus alpinus) was carried out with gill nets in Lake Ovre Stavatjonn, a small mountain lake in central Norway. The estimated density in 1979 was 1,100 Arctic char (71 kg) per hectare. The total annual yield decreased consistently from 18.0 kg/hectare in 1979 to 3.0 kg/hectare in 1984. This high fishing mortality greatly influenced the population structure, turnover (production-to-biomass ratio), age composition, growth rate, and length-frequency distributions. The yield of Arctic char that weighed over 125 g was greatly increased from 1979 to 1984. According to the Graham model, the maximum sustainable annual yield should be 7 kg/hectare, a reasonable estimate of annual surplus production that could be harvested in the lake under constant exploitation.

Transmission of Diphyllobothrium ditremum to Arctic Char (Salvelinus alpinus) in Two Subarctic Quebec lakes

Diphyllobothrium ditremum (Cestoda: Pseudophyllidea) transmission to arctic char (Salvelinus alpinus) was investigated at two small (<10 ha) lakes in northern Quebec, where the char populations exhibit a marked difference in plerocercoid prevalence (78 vs. 18%) and abundance (27.7 vs. 1.2 plerocercoids/fish). The highly infected char population was characterized by slow growth and poor feeding conditions. Feeding behavior of char in the two lakes differed principally in the fall, when consumption of benthos significantly decreased in the highly infected population as char fed more on copepods or sticklebacks (Gasterosteus aculeatus). Presence of these two food items in char stomachs was associated with high abundance of D. ditremum. The availability of alternative foods, such as larval insects and amphipods, appears to prevent char from acquiring heavy infections of D. ditremum, even in circumstances where all potential hosts are present.

Locomotor Response by Arctic Char (Salvelinus alpinus) to Gradients of H⁺ and CO₂

Evidence from the literature suggests that fish are more responsive to CO₂ than H⁺ when these two stimuli appear together. Here Arctic char were presented with plumes of H⁺ and CO₂ and their preference/avoidance responses compared with those obtained with acidified, moderately hard water. Hydrochloric acid presented in pH 7.0 decarbonated water was attractive when plume pH exceeded 5.5 but avoided at higher concentrations down to pH 3.3. The avoidance of plumes less than pH 5.5 was not diminished by lowering ambient pH to 5.5. Carbon dioxide plumes were avoided at plume/ambient gradients greater than 50 μmol/liter but was attractive at lower concentrations. The response to acidified natural water closely followed the concentration-response curve for CO₂ but not H⁺. The results, therefore, demonstrate that fish behaviorally discriminate between H⁺ and CO₂, relying principally on the latter for orientation within H⁺/CO₂ gradients. However, fish can use H⁺ alone to avoid lethal levels of pH.

Cannibalism in whitefish (Coregonus lavaretus).

Cannibalism in whitefish (Coregonus lavaretus) is studied on the basis of an evolutionary model. The model predicts that individuals may be cannibalistic if they gain sufficiently in terms of fitness relative to the reduction in survival caused by this behaviour. If cannibalistic forms mainly increase survival it is predicted that cannibalism is particularly likely to be an evolutionarily optimal strategy if only a few age classes are being cannibalized and if, simultaneously, many age classes are cannibalistic. The same pattern, although less apparent, emerges on the basis of a model assuming that cannibalistic forms mainly increase fecundity.The whitefish in River Sokna spawn during late October to late November. Males dominate the spawning run numerically. Growth rate in mature stages is low, 1.0 cm·y-1 for males and 1.3 cm·y-1 for females. Yearly survival rate in mature stages is 0.574, and survival from egg to mature is 0.000078%. Larger whitefish on the average lay more and larger eggs than do smaller. Females were more cannibalistic than males; in total cannibalism contributed to an egg mortality of at least 8.8%. This is consistent with the derived theoretical predictions.Our theoretical and empirical analyses on whitefish are supported by the observed lack of sexual differences in the cannibalistic behaviour of brown trout (Salmo trutta) and Arctic char (Salvelinus alpinus).

Effects of liming on fisheries

Liming measures for treating acidified surface waters have been carried out in Sweden for a trial period with the aid of Government grants. The aim was to study whether lime treatment was a possible method of protecting waters of special value for fisheries, nature conservation or recreational uses. In all waters where liming resulted in a sufficient and durable pH increase, the fish started to reproduce again, even if the populations were composed of very few and old individuals at the time of treatment. In waters with weak recruitment one or more rich year classes appeared after liming. Restocking of extinct populations of Arctic char ( Salvelinus alpinus )and brown trout ( Salmo trutta ) after lime treatment resulted in self-reproducing populations. In populations with intact recruitment, individual growth rates were generally not affected but in weak populations with fast individual growth rates, growth rates decreased after liming. Liming of acidic inlet waters that have high concentrations of aluminium led to heavy mortality in fish farms as did acid spring runoff flowing into a lime treated lake. Rainbow trout introduced into lakes shortly after liming also experienced high mortality. Lime treatm ent can never be a definite cure for acidified waters, but may protect fish populations in lakes with long turnover times in areas with relatively low acid deposition. Periods of high runoff in streams, rivers and lakes with short turnover times were difficult to treat with lime. In areas with a high acid load and acidified watersheds, liming of lakes and running waters will not prevent acid groundwater with elevated concentrations of toxic metals from entering surface waters.

Identification of anadromous Arctic charr (Salvelinus alpinus) stocks in coastal areas of northern Labrador based on a multivariate statistical analysis of meristic data

Variation in meristic characters of northern Labrador anadromous Arctic charr (Salvelinus alpinus) was analysed using a recently developed multivariate statistical technique for meristic data. Meristic characters of 1037 specimens from seven areas were analysed. Results suggest that at least seven discrete stocks can be identified. Separation of stocks based on meristic characters is substantiated by differences in biological characteristics such as growth rate, age at maturation, and distribution patterns of tagged fish. Pectoral fin ray and upper gill raker counts on the first left gill arch were found to be the most important characters in identifying different stocks of northern Labrador Arctic charr.

Metazoan parasites of arctic char (Salvelinus alpinus L.) in a high arctic, landlocked lake in Canada

Seven species of parasitic metazoans were found in 71 arctic char (Salvelinus alpinus L.) taken in Char Lake, Cornwallis Island, N.W.T., Canada (74°42′ N, 94°50′ W): Tetraonchus alaskensis (Monogenea); Diphyllobothrium sp. (plerocercoids), Eubothrium salvelini, Eubothrium sp., and Proteocephalus longicollis (Cestoidea); Cystidicola cristivomeri (Nematoda) and Salmincola edwardsii (Crustacea: Copepoda). Except for S. edwardsii these reports, from a population of S. alpinus which is confined to fresh water, constitute new northerly distribution records for North America. Reports of P. longicollis and C. cristivomeri from S. alpinus in Canada have not been published previously.

Movements of Stream-Resident and Anadromous Arctic Char (Salvelinus alpinus) in a Perennial Spring on the Canning River, Alaska

Perennial springs in arctic drainages are used extensively by freshwater-resident and anadromous segments of Arctic char (Salvelinus alpinus) populations. Movements of these fish were monitored in a small spring on the Canning River from May 23 to October 7, 1973, dates approximating spring breakup and winter freeze-up in the drainage. Char passing through the weir ranged in size from 22-mm fry to 595-mm anadromous spawners, though most fish were juveniles measuring 60–200 mm. The spring channel was utilized as (1) a spawning area for anadromous spawners and residual males in autumn, (2) a rearing area for fry and some older juveniles in summer, and most importantly (3) an overwintering area for juvenile char, especially those in their first and second winters of life. Key words: Arctic char, movements, spawning, overwintering, growth, perennial springs, Alaska, arctic

Histochemical localization of phospholipids in the olfactory epithelium of fish.

Histochemical localization of phospholipids in the olfactory epithelium of rainbow trout (Salmo gairdneri), whitefish (Coregonus clupeaformis), Arctic char (Salvelinus alpinus), brook trout (Salvelinus fontinalis), lake trout (Salvelinus namaycush), and black bullhead (Ictalurus melas) was examined. The present results indicate that phospholipids are highly localized in the receptor neurons of all species examined, present not only in the membranes, but also in the cytoplasm. Although the phospholipids of membranes and cytoplasm may not be of the same kind, their localization suggests a role in olfactory function. The Baker acid hematein method shows clear morphological features of the olfactory neurons beyond those obtainable by routine histological methods. The technique may be useful in determining morphological changes and (or) phospholipid alterations caused by a deleterious environment.

Viable saprolegniaceae spores on the epidermis of the Salmonid fish Salmo trutta and Salvelinus alpinus

Techniques are described for monitoring Saprolegniaceae in hatchery pond water and on the epidermis of hatchery-reared brown trout Salmo trutta L. and char Salvelinus alpinus L. The water supply to the hatchery occasionally includes spores of Saprolegnia type I (taxonomically in or near the S. diclina — S. parasitica complex), which are responsible for the outbreaks of Saprolegnia infection that occur in the hatchery. The saprolegniaceae spora in the pond water increased from 200 spores/1 or less to a maximum of 22 200 spores/1 when infected fish were present in the water. This increase was solely due to Saprolegnia type I spores. Experimental applications of high concentrations of secondary zoospores of Saprolegnia type I to trout and char indicate that although the majority of spores are removed or inactivated during the first 24 h of subsequent quarantine in clean water, a small but significant number of viable spores remain on the body surface. These findings are discussed in the light of our knowledge of Saprolegnia infections of fish and in relation to the possible defence mechanisms of fish to pathogenic fungi.

Movements and Growth of Arctic Grayling (Thymallus arcticus) and Juvenile Arctic Char (Salvelinus alpinus) in a Small Arctic Stream, Alaska

Fish movements were monitored in a small arctic stream that drains into the Kavik River near Prudhoe Bay, Alaska. The stream, which flows only during summer, served as a spawning and nursery area for Arctic grayling (Thymallus arcticus). Adult grayling entered the stream shortly after breakup and left again after spawning. Juvenile grayling also entered soon after breakup and many remained throughout the summer. Grayling fry emerged from the gravel in late June or early July and remained until freeze-up (mid-September). Small numbers of Arctic char (Salvelinus alpinus) juveniles also entered the stream to feed.The growth rate of grayling in the study stream was among the fastest recorded for arctic populations. Otolith-based age determinations were preferred as scales tended to underestimate the ages of old fish. Maximum observed age was 16 and age at sexual maturity ranged from 5 to 8.

An Isolated Population of Arctic Char (Salvelinus alpinus) Inhabiting a Warm Mineral Spring Above a Waterfall at Cache Creek, Northwest Territories

Cache Creek Spring provides an unusual overwintering habitat for a population of Arctic char (Salvelinus alpinus) isolated above a falls impassable to fish moving upstream. During winter, water temperatures (14–16 C) and dissolved solid concentrations (approximately 2600 ppm) are high and oxygen concentrations (0.2–6.8 ppm) are low. Arctic char in the springs differ meristically from those downstream of the falls. The former have significantly more gillrakers (mean 21.7 compared with 21.1) and parr marks (15.1 and 13.5) but fewer pyloric caeca (26.0 and 28.2) and vertebrae (64.7 and 67.1) than the latter. Growth appears similar to that of char inhabiting more typical spring habitats.