bluuebunny/crossref_metadata_2025 huggingface dataset:
Marine Distribution of the Sea Lamprey (Petromyzon marinus) in the Northwest Atlantic
Authors: Halliday R. C.
Published: May 2008

Catch data from trawling surveys by the Canadian Department of Fisheries and Oceans and the U.S. National Marine Fisheries Service conducted between Nova Scotia and Cape Hatteras mainly during 1978–90 contained 60 records of sea lamprey (Petromyzon marinus) captures. A further 20 records were obtained from a variety of other sources. These animals ranged in length from 12 to 84 cm. Those less than 39 cm were almost all taken in bottom trawl surveys on the continential shelf or in coastal trap nets whereas most animals 56 cm and larger were caught in midwater trawls primarily along the shelf edge and over the continental slope. The data are consistent with a previously proposed 2.5-yr marine juvenile parasitic period but a 1.5-yr period cannot be ruled out until intermediate-sized animals 39–55 cm are caught. Direct and indirect evidence on host species indicates that feeding on anadromous and small marine fish may be restricted to the first juvenile year and that large pelagic fish and marine mammals are hosts at older ages. Thus, subsequent to the first winter following metamorphosis, sea lampreys are apparently pelagic in habit and possibly wide ranging in distribution in association with large pelagic hosts.
Exhaustive Exercise in "Wild" Atlantic Salmon (Salmo saiar): Acid–Base Regulation and Blood Gas Transport
Authors: Tufts B. L. , Tang Y. , Tufts K. , Boutilier R. G.
Published: May 2008

Wild Atlantic salmon (Salmo salar) collected during their spawning migration were transported to the laboratory to investigate effects of exhaustive exercise on acid–base regulation and blood gas transport. Exhaustive exercise resulted in a very large extracellular acidosis which lasted for about 4 h. Blood lactate levels were extremely high and remained significantly elevated for at least 8 h after exercise. The degree of erythrocyte pH regulation was minimal and there was a significant fall in both erythrocyte pH and haemoglobin:oxygen carriage during the recovery period. Together, the significant decrease in erythrocyte pH and a significant reduction in the arterial partial pressure of oxygen resulted in a significant fall in arterial oxygen content immediately after exercise. Thereafter, arterial oxygen content was maintained by a significant increase in hematocrit and an increase in the arterial partial pressure of oxygen. Despite the extremely large lactacidosis in these wild fish, there were no mortalities during the recovery period. However, significant mortality has been reported in studies on domestic salmonids, and this suggests that wild salmonids may be better adapted for exhaustive exercise. This result supports the rationale of a "catch and release" recreational fishery for Atlantic salmon.
Discrimination between Atlantic Salmon (Salmo salar) of North American and European Origin using Restriction Analyses of Mitochondrial DNA
Authors: Bermingham Eldredge , Forbes Stephen H. , Friedland Kevin , Pla Carles
Published: May 2008

Twenty restriction endonucleases were used to study mitochondrial DNA (mtDNA) polymorphism in 11 hatchery strains of Atlantic salmon (Salmo salar) representing geographically separated populations in Europe and North America. The North American salmon mtDNAs studied were readily distinguished, by a minimum of seven restriction site differences, from fish of European origin. These results suggested that restriction analyses of mtDNA might provide a useful method for determining the proportions of European and North American Atlantic salmon caught in the West Greenland fishery. To test this proposition, we analyzed 328 salmon caught in the 1987 West Greenland fishery including 68 fish with coded wire or Carlin tags which provided the geographic source of the tagged salmon. We correctly identified the continent of origin for 67 of the 68 physically tagged salmon using two informative restriction endonucleases. This study provides a clear indication of the usefulness of mtDNA for discriminating between European and North American Atlantic salmon caught in the West Greenland fishery and for mixed-fishery analysis in general.
Chemosensory Attraction to Home Stream Water and Conspecifics by Native Brook Trout, Salvelinus fontinalis, from two Southern New England Streams
Authors: Keefe MaryLouise , Winn Howard E.
Published: May 2008

Behavioral preference tests were used to determine whether native brook trout, Salvelinus fontinalis, from two distinct populations could chemically discriminate home stream water and stock-specific cues. Juveniles and adults from a local anadromous population demonstrated significant preferences for home stream water and conspecifics when these stimulants were paired with groundwater. However, these trout did not prefer home stream water when paired with water from an unfamiliar stream, nor chemical traces of sympatric juveniles when paired with those of allopatric juveniles. Juvenile brook trout from a freshwater resident population displayed the same chemosensory responses as the anadromous trout, although they demonstrated distinct seasonal differences in their behaviors. These landlocked juveniles also preferred home stream water when paired with water from an unfamiliar stream. Anosmic trout maintained significant preferences for home stream water and water conditioned by conspecifics over control water, indicating that olfaction is not necessary for these attractions. Gustation may have a role in the behavioral preferences of trout.
Why do Arctic Grayling (Thymallus arcticus) Get Bigger as You Go Upstream?
Authors: Hughes Nicholas F. , Reynolds James B.
Published: May 2008

During the summer Arctic grayling in interior Alaskan streams get bigger as you go upstream. We performed a fish removal experiment in a small stream to test two hypotheses about the mechanism that produces this size gradient. The first hypothesis was that all sizes of Arctic grayling prefer positions in the headwaters, but that large fish defend these, forcing smaller ones to occupy positions further downstream (the competition for ranked positions hypothesis). The second hypothesis was that small Arctic grayling actually prefer positions in downstream reaches, and that as they grow their habitat preferences change, and they move to positions further upstream (the size-dependent habitat preference hypothesis). Under this hypothesis, exclusion by other individuals plays no part in producing the whole-stream size gradient. Using the distribution pattern of fish immediately before the removal experiment we developed two sets of rules, one for each hypothesis, to predict how a smaller post removal population, with a different size structure, should be distributed. By comparing these predictions with the actual distribution pattern of the population two years after the removal, we found that the competition for ranked positions hypothesis made much more accurate predictions than the alternative.
Differences in Measurements of Smolt Development Between Wild and Hatchery-Reared Juvenile Coho Salmon (Oncorhynchus kisutch) Before and After Saltwater Exposure
Authors: Shrimpton J. Mark , Bernier Nicholas J. , Iwama George K. , Randall David J.
Published: May 2008

We compared the saltwater tolerance of coho salmon (Oncorhynchus kisutch) juveniles that were reared in different environments. The groups examined consisted of fish reared exclusively in the hatchery, a hatchery group transplanted into the upper watershed of the river (colonized), and wild fish from natural spawning broodstock in the river. Although hatchery fish were much larger than their wild or colonized counterparts, they consistently showed a reduced saltwater tolerance as assessed by a much greater perturbation in plasma sodium concentration following transfer to salt water. Within each group there was no relationship between size of the fish and saltwater tolerance. Following transfer to sea water, hatchery fish showed a significant decline in haematocrit and a significant increase in circulating plasma cortisol concentration. Neither of these changes was seen in wild smolts. Hatchery fish possessed fewer chloride cells, and lower specific activities of the enzymes Na+K+ATPase and citrate synthase. The weaker osmoregulatory ability of hatchery fish led to a greater mortality following abrupt transfer to 35‰ seawater. We believe that the differences in saltwater tolerance seen among the different groups of fish are due to rearing environment.
Changes in Cortisol Dynamics in Wild and Hatchery-Reared Juvenile Coho Salmon (Oncorhynchus kisutch) During Smoltification
Authors: Shrimpton J. Mark , Bernier Nicholas J. , Randall David J.
Published: May 2008

Cortisol dynamics were examined in hatchery and wild juvenile coho salmon (Oncorhynchus kisutch) over the spring of 1991 and 1992 when the fish were smolting. Wild fish were caught in the upper Quinsam River, British Columbia and at the downstream enumeration fence when they started to migrate. Two groups of hatchery fish were from the top and bottom ends of an earthen rearing channel. Plasma cortisol levels increased during the spring in all groups, but were significantly greater in wild than in hatchery smolts. The half-life of plasma cortisol decreased as fish smolted; however, there was no difference among the groups. Corticosteroid receptor (CR) concentration and affinity decreased during the spring. Wild fish consistently possessed the greatest gill concentration of CR. The change in dissociation constant (kD) was similar for hatchery and wild fish during spring 1991. In 1992, hatchery fish showed a similar gradual increase. In contrast, wild fish did not show an increase in kD until May. The changes in cortisol concentration in the plasma and the CR kD occurred synchronously with the increase in Na+K+ATPase activity in wild fish, which showed the greatest increase in kD, plasma cortisol, and Na+K+ATPase activity.
The Effect of Short-duration Seawater Exposure on the Swimming Performance of Wild and Hatchery-reared Juvenile Coho Salmon (Oncorhynchus kisutch) during Smoltification
Authors: Brauner C. J. , Iwama G. K. , Randall D. J.
Published: May 2008

The critical swimming velocity (Ucrit) and haematology of wild and hatchery-reared coho salmon (Oncorhynchus kisutch) juveniles were examined in either fresh water or seawater following a 24-h seawater challenge, at the time of smoltification. In fresh water, wild smolts swam faster than hatchery-reared fish but this could largely be accounted for by scaling for body size. Transfer to seawater significantly elevated resting plasma [Na+] and reduced subsequent Ucritin hatchery fish (by 12%) relative to that determined in fresh water but had no significant effect on resting plasma [Na+] and Ucritin wild fish. Swimming the fish a second time in seawater after the initial 2-h exercise period resulted in a significant reduction in Ucritrelative to that in fresh water in both wild fish (16%) and hatchery fish (a further 14%); this relatively greater impairment in Ucritin hatchery fish was due to a reduced hypo-osmoregulatory ability following seawater transfer that impairs conditions for muscle contractility and aerobic metabolism. Aerobic metabolism in seawater-exposed fish was affected in part through a reduction in haematocrit and an increase in plasma volume, reducing oxygen carrying capacity of the blood relative to conditions in fresh water.
Decline of Native Unionid Bivalves in Lake St. Clair After Infestation by the Zebra Mussel, Dreissena polymorpha
Authors: Nalepa Thomas F.
Published: May 2008

To determine impacts of the zebra mussel, Dreissena polymorpha, on bivalves in Lake St. Clair, densities of Unionidae in 1990 and 1992 (after D. polymorpha invasion) were compared with densities in 1986 (before D. polymorpha). Declines in density occurred mainly at sites in the southeastern portion of the lake where unionids were highly infested with D. polymorpha. Unionid densities at highly infested sites declined from 2.4/m2 in 1986, to 1.8/m2 in 1990, and to 0/m2 in 1992. Unionid species with light-weight shells that brood larvae over an extended period declined more between 1986 and 1990 than heavy-shelled, short-term brooders. Unionid densities at lightly infested sites located mainly in the northwestern portion of the lake did not decline: mean densities were 1.4/m2 in 1986, 1.6/m2 in 1990, and 1.4/m2 in 1992. While the mean number of D. polymorpha per unionid was <1 at these lightly infested sites in 1990, it increased to 35 by 1992. Given this relatively slow increase in D. polymorpha per unionid in this portion of the lake, continued monitoring of populations should provide a better understanding of the relationship between the extent of infestations and unionid mortality.
The Morphological Basis of Fish Age Estimation Methods Based on the Otolith of Nemadactylus macropterus
Authors: Gauldie R. W.
Published: May 2008

Relationships between the anatomy of the endolymphatic sac, sac otoconia, sagitta and astericus of Nemadactylus macropterus (Cheilodactylidae: Teleostei) are described and the variation in opaque and hyaline zones, sulcal checks, and daily microincrement widths along different growth axes of the otolith measured. The quantitative morphology of the otolith is used to compare the different age estimation techniques for N. macropterus that are based on opaque and hyaline zones, sulcal checks, and daily microincrements. Comparison of the different methods shows that at the present state of knowledge daily microincrements present the most credible age estimation method for N. macropterus.
Viability and Freshwater Performance of Atlantic Salmon (Salmo salar) × Brown Trout (Salmo trutta) Triploid Hybrids
Authors: Galbreath Peter F. , Thorgaard Gary H.
Published: May 2008

Survival to initiation of feeding and early freshwater growth were measured for both diploid (2N) and triploid (3N) Atlantic salmon (Salmo salar) and 2N and 3N hybrids between female Atlantic salmon and male brown trout (Salmo trutta) to evaluate the triploid hybrid's potential for commercial culture. Crosses were made in 1990 and 1991 and triploidy was induced by heat shock. Average survival to initiation of feeding generally did not differ among the 2N Atlantic salmon and hybrids within years, nor between the 3N crosses within years. Average survival to initiation of feeding of the 3N Atlantic salmon and hybrids relative to the corresponding 2N crosses was reduced by 2 and 9%, respectively, in 1990, and by 55 and 62%, respectively, in 1991. Five freshwater growth trials were conducted to compare the different crosses. Results indicated no consistent differences in relative growth rates, although the hybrids demonstrated greater variability in growth at age 0+.
Genetic Relationships Among Chum Salmon Populations in Southeast Alaska and Northern British Columbia
Authors: Kondzela C. M. , Guthrie C. M. , Hawkins S. L. , Russell C. d. , Helle J. H. , Gharrett A. J.
Published: May 2008

Allozymes from 46 loci were analyzed from chum salmon (Oncorhynchus keta) collected at 61 locations in southeast Alaska and northern British Columbia. Of the 42 variable loci, 21 had a common allele frequency <0.95. We observed significant heterogeneity within and among six regional groups: central southeast Alaska, Prince of Wales Island area, southern southeast Alaska – northern British Columbia, north-central British Columbia, and two groups in the Queen Charlotte Islands. Genetic variation among regions was significantly greater than within regions. The three island groups were distinct from each other and from the mainland populations. Allele frequencies were stable over time in 14 of 15 locations sampled for more than 1 yr. The geographic basis for heterogeneity among regions is confounded in part by spawning-time differences. The Prince of Wales and Queen Charlotte populations spawn in the fall; the mainland populations spawn mainly in the summer, although some overlap exists. Overall, most genetic diversity (97%) occurred within sampling locations; the remaining diversity was distributed almost equally within and among regions. Our genetic data may provide fishery managers a means to estimate stock composition in the mixed-stock fisheries near this boundary between the United States and Canada.
Determining Continent of Origin of Chum Salmon (Oncorhynchus keta) Using Genetic Stock Identification Techniques: Status of Allozyme Baseline in Asia
Authors: Winans Gary A. , Aebersold Paul B. , Urawa Shigehiko , Varnavskaya Nataly V.
Published: May 2008

A three-agency program was initiated in 1989 to develop a new multilocus genetic baseline for chum salmon (Oncorhynchus keta) in Japan and Russia for use in stock identification; allele frequencies at 77 allozyme loci are reported in 38 samples covering most of its north–south limits of distribution in Asia. In a 62-locus data set for 17 Japanese and 12 Russian samples, average heterozygosity ranged from 0.066 to 0.087 (mean 0.079) and the average number of P0.95 and P0.99 loci was 14 and 26, respectively. Tests of year-to-year variation in allele frequencies were not significant at five of six locations. For the P0.95 loci, FST values ranged from 0.007 (sMDH-B1*) to 0.154 (mAAT-2*) and averaged 0.038. A clear distinction between Russian and Japanese samples was observed at Nei's D = 0.006, and genetic differentiation generally followed a regional pattern within each country. Principal component analysis of the P0.95 loci revealed a large difference between Japanese and Russian samples. Four loci (sAAT-1,2*, mAAT-2*, LDH-A1*, and PEPLT*) had high loadings on the first two principal components. Analyses of a simulated fishery with 200 fish revealed a high degree of precision in estimating contributions to seven population groups and to country of origin.
Electrophoretic Characterization of Odd-Year Pink Salmon (Oncorhynchus gorbuscha) Populations from the Pacific Coast of Russia, and Comparison with Selected North American Populations
Authors: Shaklee James B. , Varnavskaya Natalya V.
Published: May 2008

We collected and electrophoretically analyzed a total of 558 fish from eight locations along the Pacific Coast of Russia. We successfully screened 44 enzyme-coding loci: 14 loci were polymorphic at the 0.95 level in at least one collection, an additional eight were polymorphic at the 0.99 level but not at the 0.95 level, and the remaining 22 were either monomorphic or exhibited only very rare variation in these collections. Contingency χ2 tests using the 23 most variable loci revealed significant heterogeneity among all eight collections (p = 0.028) but little or no significant heterogeneity among collections within areas (northeastern Kamchatka peninsula, p = 0.180; southwestern Kamchatka, p = 0.533; and mainland adjacent to the northwestern Sea of Okhotsk, p = 0.071). Multidimensional scaling and minimum spanning tree analyses using genetic distances among collections indicated that geographic proximity of spawning sites was not associated with genetic similarity. The eight odd-year pink salmon (Oncorhynchus gorbuscha) collections from Russia were compared with 16 collections from North America (southeastern Alaska, British Columbia, and Washington) using data for 33 loci. The Russian populations differed from the North American populations in their patterns of allelic variation at many loci. The amount of genetic differentiation among populations from different rivers in Russia was comparable to that seen within similar-sized areas in North America.
Genetic Relationships AmongSalvelinusSpecies Inferred from Allozyme Data
Authors: Crane Penelope A. , Seeb Lisa W. , Seeb James E.
Published: May 2008

We studied phylogenetic relationships in the genus Salvelinus with emphasis on S. alpinus, S. malma, and S. confluentus. Sixty allozyme loci were resolved in 422 individuals representing six species from a worldwide distribution. We used phenetic (UPGMA), phylogenetic (Fitch and Margoliash), and maximum-likelihood techniques to derive estimates of Salvelinus phylogeny. Three almost identical topologies were produced, but we chose the Fitch and Margoliash topology as the best phylogenetic estimate. The distances used to construct this tree assume that gene frequencies are affected only by genetic drift, which we argued was the dominant speciation force in Salvelinus. This topology was also the shortest. Jackknifing the Fitch and Margoliash tree resolved the branching order among the three Salvelinus subgenera: S. [Baione], S. [Cristivomer], and S. [Salvelinus]. It also revealed two sister groups within the Salvelinus subgenus: S. leucomaenis – S. confluentus and S. alpinus – S. malma.
Genetic Comparison Between Pacific Herring (Clupea pallasi) and a Norwegian Fjord Stock of Atlantic Herring (Clupea harengus)
Authors: Jørstad K. E. , Dahle G. , Paulsen O. I.
Published: May 2008

Genetic studies on populations of Atlantic herring (Clupea harengus L.) in Norwegian seawaters have revealed a number of genetically distinct fjord populations. One population in Balsfjord in northern Norway was nearly fixed for several alleles that were very rare in the Atlanto-Scandian herring stock. A comparison with a sample of Pacific herring (Clupea pallasi) from British Columbia demonstrated that these alleles were identical to the more common alleles in this species. Genetic distance estimates based on six polymorphic loci demonstrated that Balsfjord herring were more similar to Pacific herring. Balsfjord and Pacific herring were also similar in vertebrae number and spawning behaviour. Restriction fragment analyses of mitochondrial DNA using five restriction enzymes revealed distinct clones that separated different herring groups. Nucleotide sequence divergence among groups was small.
Phylogenetic Relationships among Palearctic and Nearctic Whitefish (Coregonussp.) Populations as Revealed by Mitochondrial DNA Variation
Authors: Bernatchez Louis , Dodson Julian J.
Published: May 2008

We recently documented the existence of two highly distinct mitochondrial DNA (mtDNA) phylogenetic groups of Coregonus sp. in Beringia in the absence of geographic separation. To test whether this resulted from secondary intergradation of two groups that evolved in allopatry in Eurasia and Beringia, mtDNA restriction-fragment-length polymorphisms of 210 whitefish representing 22 populations from Europe and Siberia were compared with mtDNA variation observed among 581 fish from North America. Results confirmed that Beringia represents a zone of secondary contact among endemic whitefish and a group of Eurasian origin. All Beringian populations clustered much more closely to Eurasian populations than other North American ones. We also compared mtDNA variation among Palearctic populations with that observed in North America. European populations clustered into two major mtDNA groups that exhibited a strong geographic pattern of distribution, independent of the morphological variation observed among populations: one dominated all the more northern populations and extended to Alaska–Yukon; the second largely dominated samples from central alpine lakes, and was absent from Beringia. These results suggest that central alpine lakes and northern Europe were postglacially recolonized by two genetically distinct white-fish groups that most likely evolved in allopatry followed by limited intergradation.
DNA Fingerprinting and Cloning of Hypervariable Minisatellite Repeats in Salmonids
Authors: Leung F. C. , Welt M. , Quesenberry R. D. , Shen X-Z.
Published: May 2008

We used heterologous Jeffreys' 33.6 core sequence and microsatellites (CAC)5and (CA)12as probes and compared them with probes based on the minisatellite sequences from tilapia (Oreochromis niloticus) and Atlantic salmon (Salmo salar) in fingerprinting assays. DNA fingerprints generated with the Jeffreys' 33.6 core sequence and the microsatellite (CAC)5and (CA)12probes showed complex profiles with high background, but DNA fingerprints using the tilapia and Atlantic salmon probes showed clear, less complex, informative, individual-specific DNA fingerprints suitable for analysis. We cloned and sequenced homologous repetitive sequences using a novel approach of creating a chinook salmon (Oncorhynchus tshawytscha) genomic DNA library with enriched low Cot DNA repeats for the development of DNA probes. The four types of repeats identified and sequenced were (CT)nand three Alu-like sequences. We generated DNA fingerprints using one of the minisatellite sequences as a probe. This minisatellite sequence was shown to be species specific because it is abundant in chinook and coho salmon (Oncorhynchus kisutch) genomes, but not in Atlantic salmon. These probes will provide us with the tools to study pedigree and linkage analysis, paternity testing, breeding programs, and the analysis of genetic structure within populations for aquaculture and fisheries research.
Identification of Farm-reared and Native Chinook Salmon (Oncorhynchus tshawytscha) on the West Coast of Vancouver Island, British Columbia, Using the Nuclear DNA probe B2-2
Authors: Withler R. E. , Beacham T. D. , Watkins R. F. , Stevens T. A.
Published: May 2008

The chinook salmon DNA probe B2-2 was used to distinguish farm-reared (from two commercial farms) and native chinook salmon (Oncorhynchus tshawytscha) that were sampled from five populations on the west coast of Vancouver island. The Big Qualicum River population (east coast of Vancouver Island), which is believed to be the main progenitor of domesticated broodstocks used for aquaculture in British Columbia, was also sampled. The presence or absence and integrated optical densities (IODs) of three DNA fragments at 8.3 kilo base pairs (kbp) (band 1), 6.5 kbp (band 2), and 5.6 kbp (band 3) in the hybridization patterns of B2-2 on BamHI-restricted DNA were recorded for 269 chinook salmon. The frequency of occurrence of bands 2 and 3, and all seven measurements made of the relative and absolute values of the IODs of the three bands, varied significantly among populations. The IOD of band 3 provided the best discrimination among populations. The Big Qualicum and two fish farm populations were differentiated from all five west coast native populations. Discriminant analysis and a neural network were used independently to classify correctly to type an average of 97% of the native and 83% of the farm west coast DNA patterns used as test samples.
Heterogeneity in the Distribution of Mitochondrial DNA Haplotypes in Female Rainbow Trout Spawning in Different Seasons
Authors: Danzmann Roy G. , Ferguson Moira M. , Heculuck David M.
Published: May 2008

Analysis of females spawning throughout the year (October to late February) at a commercial fish farm in Ontario, revealed significant heterogeneity in the distribution of their mitochondrial DNA (mtDNA) haplotypes. These findings are consistent with previous data from this stock and indicate that female– daughter spawning times are temporally stable. This suggests a high maternal genetic contribution to this trait. Conversely, no temporal heterogeneity in the spawning times of females with different mtDNA haplotypes was observed in an unselected government (Ontario Ministry of Natural Resources) hatchery stock recently derived from a wild naturalized population. The government hatchery stock is normally spring spawning and has much higher levels of nucleon diversity compared with the cultured stock. Therefore, it appears that only a limited number of family lines within unselected stocks may show the propensity towards greatly accelerated spawning times. Furthermore, associations between spawning time and mtDNA haplotype may only become apparent following several generations of artificial selection.
A minisatellite DNA marker for discriminating between European and North American Atlantic salmon (Salmo salar)
Authors: Taggart John B. , Verspoor Eric , Galvin Paul T. , Morán Paloma , Ferguson Andrew
Published: May 2008

A highly discriminatory and practical nuclear DNA genetic marker that can distinguish between Atlantic salmon (Salmo salar) of European and North American origin is described. Screening of 2847 European and 247 North American Atlantic salmon from much of its geographic range for variability at a minisatellite locus, Ssa-A45/2/2, revealed the continental stocks to be almost fixed for two different-sized, easily discernable alleles. Virtually all European Atlantic salmon were homozygous for a 3.00-kb allele (frequency > 0.999), while a smaller 2.77-kb allele (frequency = 0.946) predominated in all North American populations. Whereas the 2.77-kb allele was found exclusively in North American salmon, an allele indistinguishable in size from the 3.00-kb European diagnostic allele was also observed at low frequency (0.036) in North American fish. Eight other continent-specific rare alleles (highest frequency = 0.006) were also observed. The results suggest that little, if any, natural gene flow occurs between the two continental groups of Atlantic salmon.
Physiological responses and depression of humoral components of the immune system in gilthead sea bream (Sparus aurata) following daily acute stress
Authors: Sunyer J. O. , Gómez E. , Tort L. , Navarro V. , Quesada J.
Published: May 2008

Changes in the immune system indicators serum hemagglutinating activity, complement levels, antibody titer, and lymphocyte number and in the plasma levels of cortisol and glucose in the gilthead sea bream (Sparus aurata) indicated that stress was induced when fish were chased daily for 8 min with a hand-held net for 16 days. Plasma levels of cortisol and glucose were elevated after 1 day and cortisol remained above prestress levels throughout the experiment. The immune system was altered as indicated by lymphocytopenia and decreases in hemolytic activity, agglutination capacity, and antibody titer. As these results show, for the first time, that the complement system is depressed after stress, a routine complement analysis is suggested as an additional technique for assessing the health status of fish.
Macroinvertebrate production in a headwater stream during recovery from anthropogenic disturbance and hydrologic extremes
Authors: Whiles Matt R. , Wallace J. Bruce
Published: May 2008

Recovery of the macroinvertebrate community inhabiting a headwater stream (catchment 54; C54) that received 3 years of seasonal insecticide treatment was investigated. Estimates of abundance, biomass, and production in C54 during 1989 and 1990 were compared with those of a nearby undisturbed reference stream (catchment 55; C55), and those of C54 during a pretreatment year (1985). Total macroinvertebrate abundance was similar throughout pretreatment, treatment, and recovery periods of C54. In contrast, biomass and production, which decreased during treatment, increased to levels similar to those of C54 in the pretreatment year and those of the reference stream during recovery. By 1990, the functional structure of C54 was similar to that of C55 and that of C54 before the treatment. However, taxonomic and developmental stage differences within some functional groups, particularly shredders, persisted. Despite poor recovery of some larger shredder taxa, rapid recovery of a relatively small trichopteran shredder, Lepidostoma spp., contributed significantly to recovery of ecosystem processes associated with shredders. Relationships between shredder biomass and coarse particulate organic matter differed during treatment and recovery periods. Invertebrate taxa with shorter life cycles recolonized rapidly, while those with life cycles > 1 year generally displayed limited recovery. Hydrologic extremes during treatment (drought) and recovery (wet) periods affected organic matter and macroinvertebrate community dynamics in both streams, and may have influenced observed recovery patterns.
Examination of assumptions critical to body component indices: application to the giant scallop Placopecten magellanicus
Authors: Bonardelli John C. , Himmelman John H.
Published: May 2008

Allometric relations of gonadal mass to shell height for the scallop Placopecten magellanicus from Baie des Chaleurs, Gulf of St. Lawrence, varied between maturing and fully mature individuals. We describe a technique for separating the two groups. We calculated gonosomatic indices for fully mature scallops and found that the three assumptions critical to body component indices, that (i) allometric relationships for the body component being studied and the reference component do not change over the size range of animals studied, (ii) slopes in the allometric growth equation for the studied and reference components are similar, and (iii) mass of the reference component does not change over time, were violated. We examined two alternative methods for calculating body component indices. The first applied a correction factor to the gonosomatic index and the second directly scaled the component studied to maximum shell height. We recommend the latter. We identified spawning (drops in gonadal mass) between successive dates using a modified Jonckheere rank test, which is appropriate for time-series data.
The effects of hatchery and wild ancestry and experience on the relative ability of steelhead trout fry (Oncorhynchus mykiss) to avoid a benthic predator
Authors: Berejikian Barry A.
Published: May 2008

Differences in selection regimes between hatchery and natural environments and environmental stimuli, among other factors, have the potential to cause differences in predator avoidance ability between hatchery and wild steelhead trout fry (Oncorhynchus mykiss). In two separate laboratory experiments, fry raised from eggs of wild Quinault River steelhead trout survived predation by prickly sculpin (Cottus asper) significantly better than size-matched offspring of a locally derived hatchery population, which were reared under similar conditions. Wild fry also survived predation better than hatchery fry in natural stream enclosures over a 3-day test period. Experience, in the form of 50-min visual exposure to sculpin predation on "sacrificial" steelhead trout, improved the ability of fry from both populations to avoid predation by sculpin. Wild-experienced fry were eaten in the fewest number of trials followed by wild-naive, hatchery-experienced, and hatchery-naive fry. The results of this study are consistent with the hypothesis that innate predator avoidance ability has been negatively altered through domestication and that attempts to condition hatchery-reared steelhead to avoid predators may be limited for domesticated populations.
Total dissolved mercury in the water column of several natural and artificial aquatic systems of Northern Quebec (Canada)
Authors: Montgomery Shelagh , Lucotte Marc , Pichet Pierre , Mucci Alfonso
Published: May 2008

Total dissolved mercury concentrations in the water column of the La Grande-2 and Laforge-1 hydroelectric reservoirs and four neighbouring lakes near James Bay, northern Quebec, were measured to establish the impacts of extensive flooding of terrestrial environments on this potential vector of contamination to the aquatic biota. During three field visits between June and October 1993, while the sites were free from ice cover and the water column was not strongly stratified, filtered water samples were collected from multiple depths at various locations within both reservoirs and the four lakes. To compare the diverse subenvironments within the reservoir systems, sampling sites were selected to represent differences in (i) type of flooded soil, (ii) impoundment history, and (iii) water depth. At all stations total dissolved mercury concentrations were nearly constant, with an average value of 2.30 ng∙L−1 and a standard error of 0.04 ng∙L−1. Furthermore, reservoir concentrations were not statistically different from those of the lakes. Hence, we propose that the dissolved component in the water column does not play a significant role in the transfer of inorganic mercury to the aquatic food chain in recently developed hydroelectric reservoirs.
Mercury and lead profiles and burdens in soils of Quebec (Canada) before and after flooding
Authors: Grondin Agnès , Lucotte Marc , Fortin Benoit , Mucci Alfonso
Published: May 2008

Forest soils and their flooded equivalents were sampled in the Cabonga (southern Quebec) and La Grande (northern Quebec) hydroelectric complexes and analyzed at 1-cm intervals for organic C, N, Fe, Mn, Hg, and Pb. In the La Grande region, thin Cladina sp. podzols and thicker Pleurozium sp. podzols are characterized by lower Hg burdens (2500 and 5100 μg∙m−2, respectively) than the thicker but less dense soils typical of wetter environments (6000 to 8000 μg∙m−2). These differences suggest that a fraction of Hg is leached downslope from uplands (podzols) and partially accumulates in poorly drained soils (wetlands) below. Unlike Pb, Hg showed no apparent decrease in atmospheric transport over 1000 km from south to north, away from the industrialized regions. Upon inundation, the oxidation–reduction potential drops rapidly but there was no noticeable decrease in the organic C burden, with the exception of flooded podzols where the surficial organic layer may undergo erosion. In flooded wetland soils, Hg, Pb, and Fe display a partial redistribution towards the sediment–water interface, but the Hg burdens of these soils remain comparable to those of their unflooded equivalents. In contrast, the surficial erosion of the flooded podzols may represent one pathway for Hg to enter organisms in the reservoir.
Assessment of exercise capacity and respiratory muscle oxygenation in healthy children and children with congenital heart diseases
Authors: Moalla Wassim , Dupont Grégory , Temfemo Abdou , Maingourd Yves , Weston Matthew , Ahmaidi Said
Published: May 2008

Muscular and cardiorespiratory dysfunction contributes to exercise intolerance. Therefore, the aim of the present study was to characterize the cardiopulmonary response andrespiratory muscle oxygenation of children with congenital heart diseases (CHD) when compared with those of healthy children. Twelve children with CHD in New York Heart Association (NYHA) class II or III, and 14 healthy children participated in the study. All subjects performed conventional spirographic measurements and a cardiopulmonary exercise test on a cycle ergometer. Oxygen uptake (VO2), carbon dioxide production (VCO2), minute ventilation (VE), heart rate (HR), and power output were measured. Oxygenation of respiratory muscles was assessed by near-infrared spectroscopy (NIRS) during exercise and recovery. Pulmonary function was normal and no significant difference was found between groups. At rest, CHD patients had cardiorespiratory variables comparable with those of the healthy group. At submaximal intensity (ventilatory threshold) and at peak exercise, power output, HR, VO2, VCO2, and VE were significantly reduced (p < 0.01) in CHD patients. Respiratory muscles deoxygenated during exercise in both groups. However, deoxygenation was more pronounced in the CHD group than in the healthy children from an intensity of 40% up to exhaustion. Likewise, children with CHD showed a slower recovery of oxygenation than healthy children (113.4 ± 17.5 vs. 74.6 ± 13.0 s; p < 0.001). Compared with healthy children, these results demonstrated that children with CHD have reduced performance and present a defected exercise capacity. Children with CHD showed a more pronounced decrease of respiratory muscle oxygenation and slower recovery of oxygen kinetics.
Control of ventilation in humans following intermittent hypoxia
Authors: Sheel Andrew William , MacNutt Meaghan Joelle
Published: May 2008

Exposure to chronic or intermittent hypoxia produces alterations in the ventilatory response to hypoxia. These adaptations can differ depending on the severity of the hypoxic stimulus, its duration, its pattern, and the presence or absence of other chemical stimuli. As such, there are significant differences between the responses to intermittent versus continuous hypoxia. Intermittent hypoxia (IH) has been shown to elicit significant changes in the peripheral chemoresponse, but the functional implications of these changes for resting and exercise ventilation are not clear. We summarize the impact of IH on resting chemosensitivity and discuss the use of IH to better understand ventilatory control during exercise. We also suggest future directions for this relatively young field, including potential clinical applications of IH research.
Efficacy of plant sterols in novel matrices on blood lipid profiles: medium-chain triglycerides and low-fat products consumed with or without a meal
Authors: Rudkowska Iwona
Published: May 2008

Cardiovascular disease (CVD) risk can be lowered by introduction of plant sterols (PSs) to the diet, since PSs have been shown to reduce low-density lipoprotein cholesterol (LDL-C). Given that the efficacy of PSs as cholesterol-lowering agents depends on their appropriate solubilization, the cholesterol-lowering efficacy of PSs in non-traditional matrices needs to be determined. The primary aim of this thesis was to examine the consumption of PSs (i) in an oil that is rich in medium-chain triglycerides (MCTs) or (ii) low-fat yogurt with or without a meal, on changes in lipid parameters. Additional objectives were to assess the effects of MCTs with PSs on body composition and energetics, to compare the effects of PSs in a low-fat matrix consumed with or without a meal on cholesterol synthesis, to evaluate the risks of PSs in a low-fat matrix on blood levels of carotenoids and fat-soluble vitamins, and to investigate the relationship between the response to PSs, cholesterol kinetics, and genotyping. For this purpose, two randomized, controlled, crossover feeding trials were conducted. First, 23 overweight, hyperlipidemic men consumed PSs in MCTs or an olive oil control for 6 weeks each. In the second trial, 26 hyperlipidemic subjects consumed a placebo yogurt, a PS-enriched yogurt consumed with a meal, or afternoon PS-enriched yogurt as a snack for 4 weeks each. PSs, mixed within an MCT matrix, lowers plasma total cholesterol (TC) and LDL-C without changing the high-density lipoprotein cholesterol concentrations. However, no changes in body composition or energetics were observed. Second, a PS-enriched low-fat yogurt as a snack lowered TC, along with a lowering trend in LDL-C, to a greater extent than when consumed with a meal without any risk of deficiency in fat-soluble antioxidants. An increase in cholesterol biosynthesis was also observed in both PS phases compared with the control phase. In addition, 3 subjects who were non-responsive to PS intervention and had higher cholesterol absorption rates were observed; however, no recognizable pattern of genetic polymorphism was detected. Overall, these novel matrices for PS incorporation consumed with or between meals may be an effective way of decreasing the risk of CVD; however, some individuals respond better to PS intervention.
Canadian Society for Exercise Physiology position paper: resistance training in children and adolescents
Authors: Behm David G. , Faigenbaum Avery D. , Falk Baraket , Klentrou Panagiota
Published: May 2008

Many position stands and review papers have refuted the myths associated with resistance training (RT) in children and adolescents. With proper training methods, RT for children and adolescents can be relatively safe and improve overall health. The objective of this position paper and review is to highlight research and provide recommendations in aspects of RT that have not been extensively reported in the pediatric literature. In addition to the well-documented increases in muscular strength and endurance, RT has been used to improve function in pediatric patients with cystic fibrosis and cerebral palsy, as well as pediatric burn victims. Increases in children’s muscular strength have been attributed primarily to neurological adaptations due to the disproportionately higher increase in muscle strength than in muscle size. Although most studies using anthropometric measures have not shown significant muscle hypertrophy in children, more sensitive measures such as magnetic resonance imaging and ultrasound have suggested hypertrophy may occur. There is no minimum age for RT for children. However, the training and instruction must be appropriate for children and adolescents, involving a proper warm-up, cool-down, and appropriate choice of exercises. It is recommended that low- to moderate-intensity resistance exercise should be done 2–3 times/week on non-consecutive days, with 1–2 sets initially, progressing to 4 sets of 8–15 repetitions for 8–12 exercises. These exercises can include more advanced movements such as Olympic-style lifting, plyometrics, and balance training, which can enhance strength, power, co-ordination, and balance. However, specific guidelines for these more advanced techniques need to be established for youth. In conclusion, an RT program that is within a child’s or adolescent’s capacity and involves gradual progression under qualified instruction and supervision with appropriately sized equipment can involve more advanced or intense RT exercises, which can lead to functional (i.e., muscular strength, endurance, power, balance, and co-ordination) and health benefits.
Evaluation of cholesterol-lowering and antioxidant properties of sugar cane policosanols in hamsters and humans
Authors: Kassis Amira N.
Published: May 2008

Atherosclerosis prevention is now a main focus of the scientific community and pharmaceutical industry. Sugar cane policosanols (SCPs) have gained increasing popularity over the last decade as a result of numerous studies conducted in Cuba that consider SCPs as a natural alternative to statin drugs. However, independent research on policosanols was not able to replicate cholesterol reductions reported by Cuban laboratories. No independent study to date has examined the cholesterol-lowering effect and antioxidant capacity of original SCPs in humans. In addition, since independent research was criticized because of the use of alternative policosanol formulations, the source and composition of policosanol mixtures are now at the core of the policosanol controversy. The aim of this thesis project was first to compare the composition and cholesterol-lowering effects of different SCP preparations in hamsters, and second to test the cholesterol-lowering efficacy, mechanism of action, and antioxidant capacity of the original Cuban SCP in hypercholesterolemic humans. In study 1, 48 male hamsters were randomly assigned to 4 groups for a period of 4 weeks: (i) non-cholesterol control, (ii) cholesterol control, (iii) original SCPs, and (iv) alternative SCPs. Hamsters were sacrificed and blood was collected at the end of the feeding period for lipid measurements. In study 2, 21 hypercholesterolemic volunteers consumed 10 mg·d–1 of SCPs or a placebo for a period of 28 days in a crossover trial. Plasma lipid levels and low-density lipoprotein (LDL) oxidation were measured at the start and end of supplementation phases. Cholesterol absorption and synthesis were assessed using a single-isotope, single-tracer technique and deuterium incorporation, respectively. There was no significant difference in cholesterol-lowering efficacy between hamsters in the original and alternative SCP groups relative to the control. Similarly, in hypercholesterolemic humans, supplementation with original SCPs did not significantly improve lipid parameters and no change in cholesterol absorption or synthesis was observed relative to the control. In vivo assessment of LDL oxidation showed no significant changes in oxidized LDL concentration relative to baseline and control. The present thesis disagrees with previous Cuban data on the cardio-protective role of SCPs in animals and humans and supports independent studies showing no cholesterol-lowering effect and no antioxidant capacity.