Journal articles: 'Salmonids'

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Todd, C. D., A. M. Walker, M. G. Ritchie, J. A. Graves, and A. F. Walker. "Population genetic differentiation of sea lice (Lepeophtheirus salmonis) parasitic on Atlantic and Pacific salmonids: analyses of microsatellite DNA variation among wild and farmed hosts." Canadian Journal of Fisheries and Aquatic Sciences 61, no. 7 (July 1, 2004): 1176–90. http://dx.doi.org/10.1139/f04-069.

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The copepod Lepeophtheirus salmonis is ectoparasitic on Atlantic and Pacific wild salmonids. It is a major pest to Atlantic salmon (Salmo salar) aquaculture and may be implicated in recent declines of certain European wild salmonid stocks. Variation at six microsatellite loci was assessed among L. salmonis from wild and farmed salmonids in Scotland, wild sea-run brown trout (Salmo trutta) in Norway, and farmed Atlantic salmon in eastern Canada. An outgroup North Pacific sample was obtained from farmed Atlantic salmon in British Columbia. No significant differentiation was found between L. salmonis from the host species or among samples from throughout the North Atlantic. This is consistent with long-distance oceanic migration of wild hosts and larval interchange between farmed and wild host stocks being sufficient to prevent genetic divergence of L. salmonis throughout the North Atlantic. These results have important management implications for both wild stock conservation and aquaculture in that genetically, L. salmonis in the North Atlantic comprises a single population: there is no evidence of isolation of populations on farmed hosts from those on wild fish. Comparison between North Pacific and North Atlantic L. salmonis populations showed significant but low differentiation (FST = 0.06).

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Krueger, C. C., and B. May. "Ecological and Genetic Effects of Salmonid Introductions in North America." Canadian Journal of Fisheries and Aquatic Sciences 48, S1 (December 19, 1991): 66–77. http://dx.doi.org/10.1139/f91-305.

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Stocking of non-native Salmoninae into North American waters began around 1870. Brown trout (Salmo trutta) from Europe established populations across North America and is the only successful inter-continental introduction. Introductions of native salmonids within North America but outside their native ranges have been common. Ecological effects of salmonid introductions. include competition, predation on native salmonids and other fishes, environmental modification through digging of redds in stream bottom substrates during spawning, and introduction of parasites and disease to native fish. Direct genetic effects from stocked salmonids are caused by interbreeding with native species. Indirect genetic effects may result through selective forces and/or a reduction of effective population size, genetic drift, and inbreeding. Management actions used to remove non-native salmonid populations include chemical reclamation and construction of barriers to movement. Salmonid stocking as a management practice is appropriate for species or population rehabilitation. Continued stocking of non-native salmonids should cease where viable native salmonid populations exist. New introductions of Eurasian species should not be made because effects are unpredictable. Aquaculture and the creation of transgenic fish pose special threats to North American salmonids. The era of widespread, intentional introductions of salmonids by man justifiably is drawing to a close.

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Bui, Samantha, Elina Halttunen, Agnes M. Mohn, Tone Vågseth, and Frode Oppedal. "Salmon lice evasion, susceptibility, retention, and development differ amongst host salmonid species." ICES Journal of Marine Science 75, no. 3 (December 12, 2017): 1071–79. http://dx.doi.org/10.1093/icesjms/fsx222.

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Abstract With different ecological characteristics amongst salmonid species, their response to parasitic infestation is likely to vary according to their spatial and temporal overlap with the parasite. This study investigated the host–parasite interactions amongst three species of salmonids and the ectoparasitic salmon louse, Lepeophtheirus salmonis. To determine any variation in infestation parameters amongst salmonids, single population groups of Atlantic salmon (Salmo salar), chinook salmon (Onchorhynchus tshawytscha), and previously-infested and naïve sea trout (Salmo trutta) were exposed to a controlled infestation challenge. We found that chinook salmon and both sea trout groups were more susceptible to acquiring lice than Atlantic salmon. Behavioural responses during infestation were more pronounced in Atlantic and chinook salmon. Parasite development was similar in lice attached to Atlantic salmon and sea trout, but hindered on chinook salmon. At 16 days post-infestation, chinook salmon had reduced lice loads to the same level as Atlantic salmon, whilst sea trout retained their lice. These results demonstrate differences in interactions with L. salmonis amongst these species, and highlight the vulnerability of sea trout to infestation.

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Clusa, Laura, Alba Ardura, Sara Fernández, Agustín A. Roca, and Eva García-Vázquez. "An extremely sensitive nested PCR-RFLP mitochondrial marker for detection and identification of salmonids in eDNA from water samples." PeerJ 5 (February 28, 2017): e3045. http://dx.doi.org/10.7717/peerj.3045.

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BackgroundSalmonids are native from the North Hemisphere but have been introduced for aquaculture and sport fishing in the South Hemisphere and inhabit most rivers and lakes in temperate and cold regions worldwide. Five species are included in the Global Invasive Species Database: rainbow troutOncorhynchus mykiss, Atlantic salmonSalmo salar, brown troutSalmo trutta, brook troutSalvelinus fontinalis, and lake troutSalvelinus namaycush. In contrast, other salmonids are endangered in their native settings.MethodsHere we have developed a method to identify salmonid species directly from water samples, focusing on the Iberian Peninsula as a case study. We have designed nested Salmonidae-specific primers within the 16S rDNA region. From these primers and a PCR-RFLP procedure the target species can be unequivocally identified from DNA extracted from water samples.ResultsThe method was validated in aquarium experiments and in the field with water from watersheds with known salmonid populations. Finally, the method was applied to obtain a global view of the Salmonidae community in Nalón River (north coast of Spain).DiscussionThis new powerful, very sensitive (identifying the species down to 10 pg DNA/ml water) and economical tool can be applied for monitoring the presence of salmonids in a variety of situations, from checking upstream colonization after removal of river barriers to monitoring potential escapes from fish farms.

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Henríquez, Vitalia, María Verónica Rojas, and Sergio H. Marshall. "An Alternative Efficient Procedure for Purification of the Obligate Intracellular Fish Bacterial Pathogen Piscirickettsia salmonis." Applied and Environmental Microbiology 69, no. 10 (October 2003): 6268–71. http://dx.doi.org/10.1128/aem.69.10.6268-6271.2003.

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ABSTRACT Piscirickettsia salmonis is an obligate intracellular bacterial pathogen of salmonid fish and the etiological agent of the aggressive disease salmonid rickettsial syndrome. Today, this disease, also known as piscirickettsiosis, is the cause of high mortality in net pen-reared salmonids in southern Chile. Although the bacteria can be grown in tissue culture cells, genetic analysis of the organism has been hindered because of the difficulty in obtaining P. salmonis DNA free from contaminating host cell DNA. In this report, we describe a novel procedure to purify in vitro-grown bacteria with iodixanol as the substrate to run differential centrifugation gradients which, combined with DNase I digestion, yield enough pure bacteria to do DNA analysis. The efficiency of the purification procedure relies on two main issues: semiquantitative synchrony of the P. salmonis-infected Chinook salmon embryo (CHSE-214) tissue culture cells and low osmolarity of iodixanol to better resolve bacteria from the membranous structures of the host cell. This method resulted in the isolation of intact piscirickettsia organisms and removed salmon and mitochondrial DNA effectively, with only 1.0% contamination with the latter.

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Roby, Daniel D., Donald E. Lyons, David P. Craig, Ken Collis, and G. Henk Visser. "Quantifying the effect of predators on endangered species using a bioenergetics approach: Caspian terns and juvenile salmonids in the Columbia River estuary." Canadian Journal of Zoology 81, no. 2 (February 1, 2003): 250–65. http://dx.doi.org/10.1139/z02-242.

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We estimated the consumption of juvenile salmonids (Oncorhynchus spp.) and other forage fishes by Caspian terns (Sterna caspia) nesting on Rice Island in the Columbia River estuary in 1997 and 1998 using a bioenergetics modeling approach. The study was prompted by concern that Caspian tern predation might be a substantial source of mortality to out-migrating juvenile salmonids from throughout the Columbia River basin, many populations of which are listed as threatened or endangered under the U.S. Endangered Species Act. The bioenergetics model used estimates of the energy requirements of the tern population and the proportion of tern energy requirements met by various prey types. The resulting estimate of the number of juvenile salmonids consumed by Rice Island Caspian terns was 8.1 million (5.910.4 million) in 1997 and 12.4 million (9.115.7 million) in 1998. Tern predation rates on juvenile salmonids were substantial, representing up to 15% of the juveniles to reach the estuary from some listed populations. Nevertheless, based on simple age-structured models of salmonid populations, it appears unlikely that management of Caspian tern predation alone would reverse salmonid declines. Management to reduce tern predation could, however, contribute to a comprehensive strategy to recover imperiled salmonid populations in the Columbia River basin.

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Clark, Thomas C., Pierre Boudinot, and Bertrand Collet. "Evolution of the IRF Family in Salmonids." Genes 12, no. 2 (February 8, 2021): 238. http://dx.doi.org/10.3390/genes12020238.

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Interferon regulatory factors (IRFs) as a family, are major regulators of the innate antiviral response in vertebrates principally involved in regulating the expression of interferons (IFNs) and interferon-stimulated genes (ISGs). To date, nine IRFs have been identified in mammals with a 10th member also found in several avian and fish species. Through genome mining and phylogenetic analysis, we identified and characterised 23 irf genes in 6 salmonid species. This larger repertoire of IRF in salmonids results from two additional whole-genome duplications which occurred in early teleosts and salmonids, respectively. Synteny analysis was then used to identify and confirm which paralogues belonged to each subgroup and a new nomenclature was assigned to the salmonid IRFs. Furthermore, we present a full set of Real-Time PCR primers for all rainbow trout IRFs, confirmed by sequencing to ensure paralogue specificity. RT PCR was then used to examine the response of all trout irf genes in vivo, following Vibrio anguillarum and poly I:C stimulation, indicating potential functional divergence between paralogues. Overall, this study presents a comprehensive overview of the IRF family in salmonids and highlights some novel roles for the salmonid-specific IRFs in immunity.

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Scrudato, Ronald J., and William H. McDowell. "Upstream Transport of Mirex by Migrating Salmonids." Canadian Journal of Fisheries and Aquatic Sciences 46, no. 9 (September 1, 1989): 1484–88. http://dx.doi.org/10.1139/f89-190.

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Mirex is a persistent chlorinated hydrocarbon found in appreciable concentrations in sediments and pelagic organisms of Lake Ontario. Concentrations are particularly high in introduced salmonids, which spawn in considerable numbers in tributaries of the Lake. We sampled the sediments and biota of several tributary streams in the Salmon River drainage basin. Greater concentrations of mirex were found in the resident brown trout (Salmo trutta) of tributaries accessible to migrating salmonids than in a nearby reference tributary inaccessible to migration. No significant differences in mirex concentrations were found in lower trophic levels (crayfish and stoneflies) or sediments, although mirex was detected in all samples. Because point sources of mirex are distant from these tributaries we conclude that migrating salmonids make a significant contribution to the upstream transport of mirex from Lake Ontario. Ingestion of salmonid eggs by brown trout, decomposition of salmonid carcasses by blowfly larvae, and ingestion of carcasses by aquatic and terrestrial scavengers are all means by which the contaminant is introduced to upstream environments.

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Sittenthaler, Marcia, Lucia Koskoff, Kurt Pinter, Ursula Nopp-Mayr, Rosemarie Parz-Gollner, and Klaus Hackländer. "Fish size selection and diet composition of Eurasian otters (Lutra lutra) in salmonid streams: Picky gourmets rather than opportunists?" Knowledge & Management of Aquatic Ecosystems, no. 420 (2019): 29. http://dx.doi.org/10.1051/kmae/2019020.

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Knowledge on predator diet and drivers of prey selection is particularly of interest for an efficient management of predator and prey populations where predators potentially compete with humans for resources. Actual or perceived predation by Eurasian otter (Lutra lutra) on fish stocks generates conflicts in many countries. Recently, conflicts are heating up in riverine habitats, where multiple stressors affect stream fish populations. We combined dietary analysis of otter faeces and prey fish availability in three Austrian streams to assess spatial and seasonal differences in diet composition, the extent of (salmonid) fish consumption and the selection for specific salmonid fish sizes relative to their availability. Otters in upper reaches of temperate salmonid streams occupied a narrow trophic niche. Overall, otters fed predominantly on fish with salmonids dominating diet, both in terms of frequency and ingested biomass measures. Within the category of salmonids, otters selected for specific size classes. Concurrently, otters also displayed an opportunistic feeding behaviour, and seasonally and locally non-fish prey and other fish species than salmonids became key resources. Diet composition and salmonid size selection varied significantly within and between streams, which we relate to spatio-temporal variations of prey community composition and stream-specific habitat characteristics affecting prey vulnerability.

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Wood, C. C. "Predation of Juvenile Pacific Salmon by the Common Merganser (Mergus merganser) on Eastern Vancouver Island. I: Predation during the Seaward Migration." Canadian Journal of Fisheries and Aquatic Sciences 44, no. 5 (May 1, 1987): 941–49. http://dx.doi.org/10.1139/f87-112.

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Predation of juvenile salmonids by the common merganser (Mergus merganser) was investigated during the period of seaward migration in two streams where fish populations are enhanced by spawning channels and hatcheries. Observation of foraging behaviour and crop-gullet contents indicated that, during this period, mergansers foraging on freshwater reaches of the streams ate juvenile salmonids almost exclusively whereas those foraging on tidal waters rarely ate salmonids. Maximum rates of salmonid mortality were estimated by assessing merganser abundance and the pattern of foraging activity on fresh versus tidal waters. Maximum mortality rate declined as fish abundance increased (i.e. mortality was depensatory) in all cases where the effects of prey size-selection could be ignored owing to an overwhelming abundance of one prey species. Bounds on maximum mortality rate by species for the entire migration period were computed under different hypotheses about the prey size-selection habits of mergansers; maximum mortality rate did not exceed 10% for any salmonid species over the entire seaward migration.

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Solé, Marta, Marc Lenoir, José-Manuel Fortuño, Steffen De Vreese, Mike van der Schaar, and Michel André. "Sea Lice Are Sensitive to Low Frequency Sounds." Journal of Marine Science and Engineering 9, no. 7 (July 12, 2021): 765. http://dx.doi.org/10.3390/jmse9070765.

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The salmon louse Lepeophtheirus salmonis is a major disease problem in salmonids farming and there are indications that it also plays a role in the decline of wild salmon stocks. This study shows the first ultrastructural images of pathological changes in the sensory setae of the first antenna and in inner tissues in different stages of L. salmonis development after sound exposure in laboratory and sea conditions. Given the current ineffectiveness of traditional methods to eradicate this plague, and the strong impact on the environment these treatments often provoke, the described response to sounds and the associated injuries in the lice sensory organs could represent an interesting basis for developing a bioacoustics method to prevent lice infection and to treat affected salmons.

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Railsback, Steven F., Bret C. Harvey, Sarah J. Kupferberg, Margaret M. Lang, Scott McBain, and Hart H. Welsh. "Modeling potential river management conflicts between frogs and salmonids." Canadian Journal of Fisheries and Aquatic Sciences 73, no. 5 (May 2016): 773–84. http://dx.doi.org/10.1139/cjfas-2015-0267.

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Management of regulated rivers for yellow-legged frogs (Rana boylii) and salmonids exemplifies potential conflicts among species adapted to different parts of the natural flow and temperature regimes. Yellow-legged frogs oviposit in rivers in spring and depend on declining flows and warming temperatures for egg and tadpole survival and growth, whereas salmonid management can include high spring flows and low-temperature reservoir releases. We built a model of how flow and temperature affect frog breeding success. Its mechanisms include adults selecting oviposition sites to balance risks of egg dewatering by decreasing flow versus scouring by high flow, temperature effects on development, habitat selection by tadpoles, and mortality via dewatering and scouring. In simulations of a regulated river managed primarily for salmonids, below-natural temperatures delayed tadpole metamorphosis into froglets, which can reduce overwinter survival. However, mitigating this impact via higher temperatures was predicted to cause adults to oviposit before spring flow releases for salmonids, which then scoured the egg masses. The relative timing of frog oviposition and high flow releases appears critical in determining conflicts between salmonid and frog management.

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Keeley, Ernest R., and James WA Grant. "Prey size of salmonid fishes in streams, lakes, and oceans." Canadian Journal of Fisheries and Aquatic Sciences 58, no. 6 (June 1, 2001): 1122–32. http://dx.doi.org/10.1139/f01-060.

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The growth rate of salmonid fishes is typically fastest in oceans, intermediate in lakes, and slowest in streams. We compiled literature data to test whether differences in the size of prey eaten by salmonids in the three habitats could account for these differences in growth rate (i.e., the prey-size hypothesis). In all three habitats, salmonid fishes exhibited ontogenetic niche shifts from feeding primarily on invertebrates when small to feeding on fishes when large. Contrary to the prey-size hypothesis, invertebrates eaten in streams were larger than those eaten in lakes or oceans, whereas fish eaten in oceans were smaller than those eaten in streams or lakes. Consistent with the prey-size hypothesis, salmonids began eating fish at a smaller size in oceans (8 cm) than in lakes (15 cm) or streams (27 cm). However, the size at which salmonids became predominantly piscivorous (31 cm) did not differ significantly between habitats. We suggest that the difference in growth potential between the three habitats is partly related to the size at which fish first enter the diet.

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Jansen, Peder A., Anja B. Kristoffersen, Hildegunn Viljugrein, Daniel Jimenez, Magne Aldrin, and Audun Stien. "Sea lice as a density-dependent constraint to salmonid farming." Proceedings of the Royal Society B: Biological Sciences 279, no. 1737 (February 8, 2012): 2330–38. http://dx.doi.org/10.1098/rspb.2012.0084.

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Fisheries catches worldwide have shown no increase over the last two decades, while aquaculture has been booming. To cover the demand for fish in the growing human population, continued high growth rates in aquaculture are needed. A potential constraint to such growth is infectious diseases, as disease transmission rates are expected to increase with increasing densities of farmed fish. Using an extensive dataset from all farms growing salmonids along the Norwegian coast, we document that densities of farmed salmonids surrounding individual farms have a strong effect on farm levels of parasitic sea lice and efforts to control sea lice infections. Furthermore, increased intervention efforts have been unsuccessful in controlling elevated infection levels in high salmonid density areas in 2009–2010. Our results emphasize host density effects of farmed salmonids on the population dynamics of sea lice and suggest that parasitic sea lice represent a potent negative feedback mechanism that may limit sustainable spatial densities of farmed salmonids.

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Vera-Escalona, Iván, Evelyn Habit, and Daniel E. Ruzzante. "Invasive species and postglacial colonization: their effects on the genetic diversity of a Patagonian fish." Proceedings of the Royal Society B: Biological Sciences 286, no. 1897 (February 27, 2019): 20182567. http://dx.doi.org/10.1098/rspb.2018.2567.

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The present distribution of Patagonian species is the result of a complex history involving Quaternary refugial populations, Holocene range expansions and demographic changes occurring during the Anthropocene. Invasive salmonids were introduced in Patagonia during the last century, occupying most rivers and lakes, preying on and competing with native species, including the fishGalaxias platei. Here, we usedG. plateias a case study to understand how long-term (i.e. population differentiation during the Holocene) and short-term historical processes (salmonid introductions) affect genetic diversity. Using a suite of microsatellite markers, we found that the number of alleles is negatively correlated with the presence of salmonids (short-term processes), withG. plateipopulations from lakes with salmonids exhibiting significantly lower genetic diversity than populations from lakes without salmonids. Simulations (100 years backwards) showed that this difference in genetic diversity can be explained by a 99% reduction in population size. Allelic richness and observed heterozygosities were also negatively correlated with the presence of salmonids, but also positively correlated with long-term processes linked to Quaternary glaciations. Our results show how different genetic parameters can help identify processes taking place at different scales and their importance in terms of conservation.

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Sudhagar, Arun, Gokhlesh Kumar, and Mansour El-Matbouli. "The Malacosporean Myxozoan Parasite Tetracapsuloides bryosalmonae: A Threat to Wild Salmonids." Pathogens 9, no. 1 (December 23, 2019): 16. http://dx.doi.org/10.3390/pathogens9010016.

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Tetracapsuloides bryosalmonae is a myxozoan parasite responsible for proliferative kidney disease (PKD) in a wide range of salmonids. PKD, characterized by high mortality and morbidity, is well known for affecting aquaculture operations and wild salmonid populations across Europe and North America. The life cycle of T. bryosalmonae revolves around freshwater bryozoan and salmonid fish hosts. In recent years, T. bryosalmonae has been reported among wild salmonids from the European countries where it has not been reported previously. T. bryosalmonae is believed to be a possible reason for the diminishing wild salmonid populations in the natural water bodies of many European countries. Climate crisis driven rising water temperature can further accelerate the distribution of T. bryosalmonae. Expansion of the geographical distribution of T. bryosalmonae may further advocate the decline of wild salmonid populations, especially brown trout (Salmo trutta) in their habitats. Mathematical models are used to understand the pattern and distribution of T. bryosalmonae among the host in the natural water bodies. The present manuscript not only summarizes the incidences of T. bryosalmonae among the wild salmonid populations, but also discusses the contemporary understanding about the development of T. bryosalmonae in its hosts and the influences of various factors in the spread of the disease in the wild.

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Scrivener, J. Charles, Thomas G. Brown, and Bruce C. Andersen. "Juvenile Chinook Salmon (Oncorhynchus tshawytscha) Utilization of Hawks Creek, a Small and Nonnatal Tributary of the Upper Fraser River." Canadian Journal of Fisheries and Aquatic Sciences 51, no. 5 (May 1, 1994): 1139–46. http://dx.doi.org/10.1139/f94-113.

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Hawks Creek, a small tributary of the upper Fraser River where there is no record of spawning salmonids, was examined from May to November 1990 for the presence of juvenile salmonids. Age 0+ wild chinook salmon (Oncorhynchus tshawytscha) appeared in May, increased to peak densities of 0.76 fish∙m−2 in late August, and were absent in November. Average residence time of marked chinook juveniles was 9 d. Duration of residency was size dependent, as small fish remained longer than large fish. Rainbow trout (Oncorhynchus mykiss) and mountain whitefish (Prosopium williamsoni) also had a short residency (mean = 21 d). We suggest that unsuitable rearing conditions (e.g., sediment load) in the mainstem Fraser River during the spring and summer favour the use of small, clear, and nonnatal tributaries by juvenile salmonids. Physical and biological explanations are proposed for their temporary use. These salmonid refuge habitats need to be protected.

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Marshall, Sergio, Sekou Heath, Vitalia Henríquez, and Cristián Orrego. "Minimally Invasive Detection ofPiscirickettsia salmonis in Cultivated Salmonids via the PCR." Applied and Environmental Microbiology 64, no. 8 (August 1, 1998): 3066–69. http://dx.doi.org/10.1128/aem.64.8.3066-3069.1998.

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ABSTRACT The attributes of the PCR allowed implementation of an assay for specific detection of Piscirickettsia salmonis from a few microliters of fish serum. This opens the way to less invasive modes of sampling for this microbial pathogen in salmonids.

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Heuch, Peter Andreas, Aengus Parsons, and Karin Boxaspen. "Diel vertical migration: A possible host-finding mechanism in salmon louse (Lepeophtheirus salmonis) copepodids?" Canadian Journal of Fisheries and Aquatic Sciences 52, no. 4 (April 1, 1995): 681–89. http://dx.doi.org/10.1139/f95-069.

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The vertical distribution of pelagic nauplii and copepodids of the salmon louse Lepeophtheirus salmonis Krøyer was studied in large enclosures in the sea. Copepodids, which infect salmonid hosts, displayed a distinct diel vertical migration pattern. They gathered near the surface during the day, and spread out into deeper layers at night. Nauplii showed only small differences in depth between night and day. Copepodid distribution seems to be controlled by light intensity; no effect of either salinity or temperature was found. This migration pattern, which is the reverse of that of wild salmonids, may increase the number of parasite–host encounters as hosts will swim through populations of sinking (nighttime) and rising (dawn) parasites every 24 h. Because caged salmon feed at the surface during the day, they are likely to be more exposed to infective copepodids than wild fish.

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Limburg, Karin E., and Mikael Elfman. "Patterns and magnitude of Zn:Ca in otoliths support the recent phylogenetic typology of Salmoniformes and their sister groups." Canadian Journal of Fisheries and Aquatic Sciences 67, no. 4 (April 2010): 597–604. http://dx.doi.org/10.1139/f10-014.

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Fish otolith chemistries are used to associate fishes with specific environments. However, otolith chemistry may also have potential as a tool in phylogenetic research, as demonstrated here in salmoniform fishes and related taxa. Two-dimensional maps of Zn:Ca otolith chemistry displayed annual oscillations in magnitude in members of the Salmoniformes (with salmons differing from whitefishes). These are also detectable in esocids, but not strongly in osmerids or in more distantly related taxa. Further, Zn:Ca magnitudes were highest in salmonids and declined in other taxa: salmonids (salmons, grayling, and whitefishes) > esocids > osmerids > other. We performed spatial analysis on sagittal section Zn:Ca maps, dividing them into five zones and obtaining means within each zone, as well as grand means. Discriminant function analysis of the different otolith zones was better able to separate taxonomic groups, but showed pike grouping more closely with salmonids and osmerids with the out-group. Zn:Ca incorporation in otoliths may be a trait under phylogenetic control, and recent re-ordering of the systematics of Salmoniformes and their sister groups may be supported by otolith Zn:Ca chemistry.

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Wagner, Glenn N., Mark D. Fast, and Stewart C. Johnson. "Physiology and immunology of Lepeophtheirus salmonis infections of salmonids." Trends in Parasitology 24, no. 4 (April 2008): 176–83. http://dx.doi.org/10.1016/j.pt.2007.12.010.

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Johnson, S. C., and L. J. Albright. "The developmental stages of Lepeophtheirus salmonis (Krøyer, 1837) (Copepoda: Caligidae)." Canadian Journal of Zoology 69, no. 4 (April 1, 1991): 929–50. http://dx.doi.org/10.1139/z91-138.

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Lepeophtheirus salmonis (Copepoda: Caligoida) is an economically important marine ectoparasite of wild and pen-reared salmonids. The morphology of its developmental stages is described and compared with that of other species of Lepeophtheirus and Caligus. The development of L. salmonis is very similar to that reported for other Lepeophtheirus species. The appendages generally attain the adult condition and the sexes become distinguishable later in development than in Caligus species. At all developmental stages except the nauplius, L. salmonis can be distinguished from the co-occurring Caligus clemensi.

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House, Robert A., and Paul L. Boehne. "The Effect of Stream Cleaning on Salmonid Habitat and Populations in a Coastal Oregon Drainage." Western Journal of Applied Forestry 2, no. 3 (July 1, 1987): 84–87. http://dx.doi.org/10.1093/wjaf/2.3.84.

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Abstract Habitat conditions and use by anadromous salmonids were evaluated in five reaches of Upper Lobster Creek, a major stream system in the central Oregon Coast Range, to determine the effect of different levels of stream cleaning. Stream clearance associated with post-World War II logging practices and a 100-year flood event that occured in 1964 severely altered channel configurations and loading patterns of large woody debris. This caused the subsequent removal of log jams. An uncleaned reach had large amounts of woody debris and the highest density of pools, greatest percentage of off-channel habitat, and highest salmonid use. In contrast, a totally cleaned reach had the lowest density of pools and lowest salmonid use. Rehabilitated sections of a reach that had been partially cleaned showed increases in density of pools and salmonid use compared to the remainder of the partially cleaned reach. Retention of standing timber in the riparian zone and maintenance in instream accumulations of large woody debris is recommended to allow streams to reach their productive potential for anadromous salmonids. West. J. Appl. For. 2(3):84-87, July 1987.

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Lennox, Robert J., Ulrich Pulg, Brendan Malley, Sven-Erik Gabrielsen, Erlend M. Hanssen, Steven J. Cooke, Kim Birnie-Gauvin, Bjørn T. Barlaup, and Knut Wiik Vollset. "The various ways that anadromous salmonids use lake habitats to complete their life history." Canadian Journal of Fisheries and Aquatic Sciences 78, no. 1 (January 2021): 90–100. http://dx.doi.org/10.1139/cjfas-2020-0225.

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Despite the preponderance of exorheic lakes in rivers home to anadromous salmonids, little research has focused on how salmon, trout, and char use lakes as part of their anadromous life histories. The literature on this subject has so far revealed that some parr move into lakes to feed and grow before smoltification but that smolts moving through lakes tend to have high mortality in disproportion to what is observed in other habitats they migrate in or through. Adults have been observed using lakes for behavioural thermoregulation prior to spawning, and kelts of iteroparous species often exploit lakes to overwinter before returning to sea to recondition. We summarized knowledge on lakes as salmonid habitat and identified knowledge gaps about the use of lakes by anadromous salmonids related to whether lakes are barriers that structure genetics of populations, whether mortality in lakes is compensatory or additive, and whether systems with lakes have higher rates of repeat spawning among iteroparous salmonids. Human activities that alter lakes require further study to understand how changes in temperature, oxygen, ice, or circulation affect navigation and fate.

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Gibeau, P., B. M. Connors, and W. J. Palen. "Run-of-River hydropower and salmonids: potential effects and perspective on future research." Canadian Journal of Fisheries and Aquatic Sciences 74, no. 7 (July 2017): 1135–49. http://dx.doi.org/10.1139/cjfas-2016-0253.

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The spatial footprint of individual run-of-river (RoR) hydropower facilities is smaller than reservoir-storage hydroelectric projects and their impacts to aquatic ecosystems are often assumed to be negligible. However, these effects are poorly understood, especially for salmonids whose freshwater habitat often overlaps with RoR hydropower potential. Flow regulation for RoR hydropower is unique in how it influences the seasonality and magnitude of flow diversion and because low-head dams can be overtopped at high flows. Based on a review of the primary literature, we identified three pathways of effects by which RoR hydropower may influence salmonids: reduction of flow, presence of low-head dams impounding rivers, and anthropogenic flow fluctuations. We synthesized empirical evidence of effects of RoR hydropower on river ecosystems from 31 papers, of which only 10 explicitly considered salmonids. We identified key research gaps including impacts of extended low-flow periods, anthropogenic flow fluctuations, and cumulative effects of multiple RoR projects. Filling these gaps is necessary to help manage and conserve salmonid populations in the face of the growing global demand for small-scale hydropower.

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Vollset, Knut Wiik, Robert J. Lennox, Eva B. Thorstad, Samuel Auer, Kerstin Bär, Martin H. Larsen, Shad Mahlum, Joacim Näslund, Henrik Stryhn, and Ian Dohoo. "Systematic review and meta-analysis of PIT tagging effects on mortality and growth of juvenile salmonids." Reviews in Fish Biology and Fisheries 30, no. 4 (October 18, 2020): 553–68. http://dx.doi.org/10.1007/s11160-020-09611-1.

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Abstract A systematic review and meta-analysis was conducted to evaluate the appropriate tag:fish size ratio when tagging juvenile salmonids (genera Oncorhynchus, Salmo, and Salvelinus). The review yielded 18 publications with 211 control and treatment groups reporting results from laboratory studies on the effects of passive integrated transponder (PIT) tags, plus a small number of additional studies on acoustic transmitters. A meta-analysis of the PIT tagging studies showed significant heterogeneity among studies with respect to mortality. Meta-regression revealed that juvenile salmonid mortality increased curvilinearly with the tag:fish length ratio, indicating that mortality risk is rapidly enhanced as smaller fish or larger tag sizes are used. The tag:fish length ratio effect on daily length or mass gain increased linearly. The results provide an estimate of the effects of the tag:fish length ratio on mortality and growth parameters in juvenile salmonids. Based on this, we suggest that researchers can follow best practices for tagging juvenile salmonids with tags that are not greater than 17.5% of fish total length (TL). This equates a minimum size threshold of 131 mm TL for tagging salmonids with 23-mm PIT tags, and 69 mm TL with 12-mm PIT tags. This information can assist researchers, managers, and welfare agencies striving to use the best possible evidence to make informed decisions regarding fish tagging.

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Spens, Johan, and John P. Ball. "Salmonid or nonsalmonid lakes: predicting the fate of northern boreal fish communities with hierarchical filters relating to a keystone piscivore." Canadian Journal of Fisheries and Aquatic Sciences 65, no. 9 (September 2008): 1945–55. http://dx.doi.org/10.1139/f08-103.

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We determine if lacustrine salmonids show large-scale patterns of coexistence with the keystone predator northern pike ( Esox lucius ) and test an approach to predict fish communities using coexistence rules set in the context of three hierarchical filters that a species must pass to be present. The mutually exclusive species distribution patterns that we detected among 1029 lakes were repeatedly verified from results of whole-lake interventions with rotenone and introductions. Essentially, pike did not coexist with self-sustaining salmonid populations in lakes. High connectivity to pike (derived from maps) largely predicts the absence of lacustrine salmonids. Our analysis strongly suggests that pike prevented self-sustaining populations of brown trout ( Salmo trutta ), Arctic char ( Salvelinus alpinus ), and brook trout ( Salvelinus fontinalis ) in lakes. High connectivity to pike resulted in nonsalmonid lake fish communities, most often including both European perch ( Perca fluviatilis ) and roach ( Rutilus rutilus ). Our analysis suggests that if pike were not present in many boreal lakes where they now dwell, salmonid fish assemblages would prevail, a sharp contrast from the present pike-driven homogenized state with mainly nonsalmonid fish communities.

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Sullivan, Mario L., Yixin Zhang, and Timothy H. Bonner. "Terrestrial subsidies in the diets of stream fishes of the USA: comparisons among taxa and morphology." Marine and Freshwater Research 63, no. 5 (2012): 409. http://dx.doi.org/10.1071/mf11232.

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Terrestrial food subsidies are important energy sources to stream fishes worldwide. However, their importance is not fully understood, except perhaps for some salmonid communities. Using the published literature, we investigated patterns of fish taxonomy and jaw morphology in the consumption of terrestrial food subsidies by non-salmonid stream fishes in the USA. We hypothesised that: (1) in general, non-salmonid fishes would consume terrestrial food items to the same extent as salmonids; and (2) subsidy consumption would be associated with jaw morphology. Cyprinids and fundulids consumed terrestrial subsidies approaching levels observed in salmonids (20–44%) whereas other groups (e.g. catostomids and moronids) consumed far less (<2%) terrestrial food. Fishes with terminal jaw positions tended to consume more terrestrial items than those with subterminal or inferior jaw positions. Within a species, there were highly variable propensities for consuming terrestrial subsidies. Our findings justify focusing on trophic linkages between fishes and riparian systems across a wide range of taxa, especially considering the spatio-temporal variability of environmental conditions across a variety of habitats. It is necessary to assess the relative contribution of terrestrial subsidies in fish growth and population dynamics with a focus on nutritional and energetic benefits across different groups.

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Colautti, Robert I. "Are characteristics of introduced salmonid fishes biased by propagule pressure?" Canadian Journal of Fisheries and Aquatic Sciences 62, no. 4 (April 1, 2005): 950–59. http://dx.doi.org/10.1139/f05-002.

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Many recent studies of nonindigenous species (NIS) have used life history and morphological characteristics of invaders to either (i) build statistical models that predict new invaders or (ii) test ecological and evolutionary hypotheses. However, species characteristics may be confounded if NIS are transported or introduced nonrandomly with respect to the chosen contrast group, which typically consists of native or globally available species. For example, deliberately introduced NIS are often chosen according to economic rather than ecological factors. Here, I use stocking records of salmonid species introduced into Nevada, USA, to test for propagule biases within this system. I find that established salmonids are introduced significantly more times, and in greater numbers, than are those that fail and that species chosen for introduction are a nonrandom sample of the global salmonid species pool. Statistical differences among characteristics of salmonid species that established, those that were introduced, and those from the global source pool suggest that maximum reported size and weight as well as latitudinal range and midlatitude all represent propagule-biased characteristics of salmonids introduced into Nevada. These results highlight the need for caution when using characteristics of invaders to develop statistical models or to test hypotheses relevant to ecology and evolution.

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Muzzall, Patrick M. "Endohelminths of salmonids from two localities in eastern Lake Michigan, with emphasis on Echinorhynchus salmonis." Canadian Journal of Zoology 67, no. 6 (June 1, 1989): 1604–7. http://dx.doi.org/10.1139/z89-227.

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Adult salmonids (101 chinook salmon, Oncorhynchus tshawytscha; 7 coho salmon, Oncorhynchus kisutch; 56 lake trout, Salvelinus namaycush; 6 steelhead, Salmo gairdneri; and 2 brown trout, Salmo trutta) were collected from eastern Lake Michigan (Ludington and Manistee, Michigan) in July–September 1986, and examined for helminths. Eight species (three Cestoda, three Nematoda, two Acanthocephala) were found in the digestive tract and other viscera. Echinorhynchus salmonis and Eubothrium salvelini were the most common helminths found. The intensity of E. salmonis significantly increased as chinook salmon became older and longer.

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Marschall, Elizabeth A., Thomas P. Quinn, Derek A. Roff, Jeffrey A. Hutchings, Neil B. Metcalfe, Tor A. Bakke, Richard L. Saunders, and N. LeRoy Poff. "A framework for understanding Atlantic salmon (Salmo salar) life history." Canadian Journal of Fisheries and Aquatic Sciences 55, S1 (January 1, 1998): 48–58. http://dx.doi.org/10.1139/d98-007.

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We took a hierarchical approach to understanding Atlantic salmon (Salmo salar) life history patterns by first comparing salmonids to other teleosts, next comparing Atlantic salmon to other salmonids, and finally, mapping correlations among individual life history traits within Atlantic salmon. The combination of anadromy, large eggs, nest construction and egg burial by females, and large size at maturity differentiates salmonids from most other teleosts. Within the family Salmonidae, there is considerable variation in all traits but Atlantic salmon are generally in the middle of the range. Within Atlantic salmon, we were able to map correlations among individual life history traits, but we found that we still lacked an understanding comprehensive and quantitative enough to allow us to predict how the entire life history should respond to environmental changes. Thus, we proposed several general courses of action: (i) use models to synthesize complex patterns and relationships, (ii) collect long time series of data in individual systems, and (iii) design experiments to assess phenotypic plasticity and how environmental influences differ from genetic effects and constraints.

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Sutherland, Ben J. G., Jennifer M. Covello, Sarah E. Friend, Jordan D. Poley, Kim W. Koczka, Sara L. Purcell, Tara L. MacLeod, et al. "Host–parasite transcriptomics during immunostimulant-enhanced rejection of salmon lice (Lepeophtheirus salmonis) by Atlantic salmon (Salmo salar)." FACETS 2, no. 1 (May 1, 2017): 477–95. http://dx.doi.org/10.1139/facets-2017-0020.

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Salmon lice ( Lepeophtheirus salmonis) are important ectoparasites of wild and farmed salmonids and cause major losses to the salmon farming industry throughout the Northern Hemisphere. With the emergence of resistance to several commonly used parasiticides, novel control strategies and integration of multiple treatment options are needed, including host immunostimulation. Here, we investigate the effects of a functional feed containing a peptidoglycan and nucleotide formulation on L. salmonis infection of Atlantic salmon ( Salmo salar) by characterizing lice infection levels, the expression of several host immune genes, and the parasite transcriptomic response to the immunostimulated host. Although initial infection intensities were low, the low dose (LD) immunostimulant diet reduced the total lice burden by 50% relative to controls. Immunostimulant fed hosts up-regulated interleukin-1β in the skin and spleen. This gene has been implicated in successful responses of several salmonid species to salmon lice but is typically not observed in Atlantic salmon, suggesting a favorable influence on the immune response. Lice infecting LD immunostimulated salmon overexpressed genes putatively involved in parasite immunity, including carboxylesterases, and underexpressed genes putatively involved in feeding (e.g., proteases). These lice response genes further improve the characterization of the transcriptome of the non-model parasite by identifying genes potentially involved in evading host immunity.

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Blumstein, Danielle M., Matthew A. Campbell, Matthew C. Hale, Ben J. G. Sutherland, Garrett J. McKinney, Wendylee Stott, and Wesley A. Larson. "Comparative Genomic Analyses and a Novel Linkage Map for Cisco (Coregonus artedi) Provide Insights into Chromosomal Evolution and Rediploidization Across Salmonids." G3: Genes|Genomes|Genetics 10, no. 8 (July 1, 2020): 2863–78. http://dx.doi.org/10.1534/g3.120.401497.

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Whole-genome duplication (WGD) is hypothesized to be an important evolutionary mechanism that can facilitate adaptation and speciation. Genomes that exist in states of both diploidy and residual tetraploidy are of particular interest, as mechanisms that maintain the ploidy mosaic after WGD may provide important insights into evolutionary processes. The Salmonidae family exhibits residual tetraploidy, and this, combined with the evolutionary diversity formed after an ancestral autotetraploidization event, makes this group a useful study system. In this study, we generate a novel linkage map for cisco (Coregonus artedi), an economically and culturally important fish in North America and a member of the subfamily Coregoninae, which previously lacked a high-density haploid linkage map. We also conduct comparative genomic analyses to refine our understanding of chromosomal fusion/fission history across salmonids. To facilitate this comparative approach, we use the naming strategy of protokaryotype identifiers (PKs) to associate duplicated chromosomes to their putative ancestral state. The female linkage map for cisco contains 20,292 loci, 3,225 of which are likely within residually tetraploid regions. Comparative genomic analyses revealed that patterns of residual tetrasomy are generally conserved across species, although interspecific variation persists. To determine the broad-scale retention of residual tetrasomy across the salmonids, we analyze sequence similarity of currently available genomes and find evidence of residual tetrasomy in seven of the eight chromosomes that have been previously hypothesized to show this pattern. This interspecific variation in extent of rediploidization may have important implications for understanding salmonid evolutionary histories and informing future conservation efforts.

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Ciepliński, Mateusz, Mariusz Kasprzak, Monika Grandtke, Marian J. Giertych, and Aleksandra Steliga. "Pattern of secondary infection with Saprolegnia spp. in wild spawners of UDN-affected sea trout Salmo trutta m. trutta (L.), the Słupia River, N Poland." Oceanological and Hydrobiological Studies 47, no. 3 (September 25, 2018): 230–38. http://dx.doi.org/10.1515/ohs-2018-0022.

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Abstract Ulcerative dermal necrosis (UDN), a disease of unknown etiology affecting salmonids, has been observed in some rivers in the north of Poland since 2007. Fish affected by UDN die, inter alia, as a result of secondary infection caused by water molds from the Saprolegnia genus. UDN is considered to be an important factor affecting the decline of Polish salmonid populations observed in recent years. Patterns of secondary infection and differences between sexes in UDN-affected wild, adult sea trout (Salmo trutta m. trutta) during the 2014 and 2015 spawning season have been described on the basis of photographic documentation and image analysis. Male fish are most commonly infected in the dorsal region, while females in the head and tail areas. When comparing the infection patterns in both sexes, it is clear that large areas of flanks are significantly more frequently infected in males than in females. The dorsal half of the tail fin is most commonly affected by pathological changes in females. These findings are discussed in relation to various factors predisposing salmonids to Saprolegnia spp. infections during the spawning season. The presented infection patterns can be helpful in preliminary diagnosis of early stages of secondary infection with Saprolegnia spp. in UDN-affected salmonids.

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Frazey, Sharon L., and Margaret A. Wilzbach. "The Relationship Between Productivities of Salmonids and Forest Stands in Northern California Watersheds." Western Journal of Applied Forestry 22, no. 2 (April 1, 2007): 73–80. http://dx.doi.org/10.1093/wjaf/22.2.73.

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Abstract Productivities of resident salmonids and upland and riparian forests in 22 small watersheds of coastal northern California were estimated and compared to determine whether: 1) upland site productivity predicted riparian site productivity; 2) either upland or riparian site productivity predicted salmonid productivity; and 3) other parameters explained more of the variance in salmonid productivity. Upland and riparian site productivities were estimated using Site Index values for redwood (Sequoia sempervirens) and red alder (Alnus rubra), respectively. Salmonid productivity was indexed by back-calculated length at age 1 of the largest individuals sampled and by total biomass. Upland and riparian site indices were correlated, but neither factor contributed to the best approximating models of salmonid productivity. Total salmonid biomass was best described by a positive relationship with drainage area. Length of dominant fish was best described by a positive relationship with percentage of hardwoods within riparian areas, which may result from nutrient and/or litter subsidies provided by red alder. The inability of forest productivity to predict salmon productivity may reflect insufficient variation in independent variables, limitations of the indices, and the operation of other factors affecting salmonid production. The lack of an apparent relationship between upland conifer and salmonid productivity suggests that management of land for timber productivity and component streams for salmonid production in these sites will require separate, albeit integrated, management strategies.

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Lehnert, S. J., K. A. Christensen, W. E. Vandersteen, D. Sakhrani, T. E. Pitcher, J. W. Heath, B. F. Koop, D. D. Heath, and R. H. Devlin. "Carotenoid pigmentation in salmon: variation in expression at BCO2-l locus controls a key fitness trait affecting red coloration." Proceedings of the Royal Society B: Biological Sciences 286, no. 1913 (October 16, 2019): 20191588. http://dx.doi.org/10.1098/rspb.2019.1588.

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Carotenoids are primarily responsible for the characteristic red flesh coloration of salmon. Flesh coloration is an economically and evolutionarily significant trait that varies inter- and intra-specifically, yet the underlying genetic mechanism is unknown. Chinook salmon ( Oncorhynchus tshawytscha ) represents an ideal system to study carotenoid variation as, unlike other salmonids, they exhibit extreme differences in carotenoid utilization due to genetic polymorphisms. Here, we crossed populations of Chinook salmon with fixed differences in flesh coloration (red versus white) for a genome-wide association study to identify loci associated with pigmentation. Here, the beta-carotene oxygenase 2-like ( BCO2-l ) gene was significantly associated with flesh colour, with the most significant single nucleotide polymorphism explaining 66% of the variation in colour. BCO2 gene disruption is linked to carotenoid accumulation in other taxa, therefore we hypothesize that an ancestral mutation partially disrupting BCO2-l activity (i.e. hypomorphic mutation) allowed the deposition and accumulation of carotenoids within Salmonidae. Indeed, we found elevated transcript levels of BCO2-l in white Chinook salmon relative to red. The long-standing mystery of why salmon are red, while no other fishes are, is thus probably explained by a hypomorphic mutation in the proto-salmonid at the time of divergence of red-fleshed salmonid genera (approx. 30 Ma).

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Gaffaroglu, Muhammet, Zuzana Majtánová, Radka Symonová, Šárka Pelikánová, Sevgi Unal, Zdeněk Lajbner, and Petr Ráb. "Present and Future Salmonid Cytogenetics." Genes 11, no. 12 (December 6, 2020): 1462. http://dx.doi.org/10.3390/genes11121462.

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Salmonids are extremely important economically and scientifically; therefore, dynamic developments in their research have occurred and will continue occurring in the future. At the same time, their complex phylogeny and taxonomy are challenging for traditional approaches in research. Here, we first provide discoveries regarding the hitherto completely unknown cytogenetic characteristics of the Anatolian endemic flathead trout, Salmo platycephalus, and summarize the presently known, albeit highly complicated, situation in the genus Salmo. Secondly, by outlining future directions of salmonid cytogenomics, we have produced a prototypical virtual karyotype of Salmo trutta, the closest relative of S. platycephalus. This production is now possible thanks to the high-quality genome assembled to the chromosome level in S. trutta via soft-masking, including a direct labelling of repetitive sequences along the chromosome sequence. Repetitive sequences were crucial for traditional fish cytogenetics and hence should also be utilized in fish cytogenomics. As such virtual karyotypes become increasingly available in the very near future, it is necessary to integrate both present and future approaches to maximize their respective benefits. Finally, we show how the presumably repetitive sequences in salmonids can change the understanding of the overall relationship between genome size and G+C content, creating another outstanding question in salmonid cytogenomics waiting to be resolved.

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Carter, C. G., D. F. Houlihan, I. D. McCarthy, A. I. Mitchell, and B. Buchanan. "Environmental implications of nutrition and metabolism of salmonids." Proceedings of the British Society of Animal Production (1972) 1992 (March 1992): 77. http://dx.doi.org/10.1017/s0308229600021929.

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In farmed salmonids the majority of consumed nitrogen is lost in metabolic waste products (mainly ammonia) and the faeces (Table 1). Any improvement in nitrogen retention, brought about by reductions in these components, would decrease environmental load. Inter-individual variation in retained nitrogen has been little investigated as a basis for selection of more efficient fish; this communication points to an experimental approach to measuring individual variation by concentrating on digestive efficiency and protein turnover as possible contributors to nitrogen retention. The utilization of dietary nitrogen was investigated in two species of farmed salmonid, the rainbow trout, Oncorhynchus mykiss and the Atlantic salmon, Salmo salar.

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Yanovych, D., І. Hrytsyniak, and T. Shvets. "APPLICATION OF SALMONIDS (SALMONIDAE) IN THE BIOMONITORING OF AQUATIC ENVIRONMENT." Ribogospodarsʹka nauka Ukraïni, no. 1(35) (March 24, 2016): 5–30. http://dx.doi.org/10.15407/fsu2016.01.005.

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Gómez, Daniela, Pablo Conejeros, Sofia Consuegra, and Sergio H. Marshall. "MHC mediated resistance to Piscirickettsia salmonis in salmonids farmed in Chile." Aquaculture 318, no. 1-2 (July 2011): 15–19. http://dx.doi.org/10.1016/j.aquaculture.2011.04.023.

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MIKHEEV, V. N., A. F. PASTERNAK, and E. T. VALTONEN. "Host specificity of Argulus coregoni (Crustacea: Branchiura) increases at maturation." Parasitology 134, no. 12 (July 13, 2007): 1767–74. http://dx.doi.org/10.1017/s0031182007003125.

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SUMMARYWe tested the hypothesis that host specificity in ectoparasites does not depend exclusively on the features of the host but also on surrounding habitats, using 2 fish ectoparasites, Argulus coregoni and A. foliaceus (Crustacea: Branchiura), occurring sympatrically in Finnish lakes. Although these parasites are considered to be of low specificity, we found that the larger of the 2 species, A. coregoni developed a pronounced preference for salmonid hosts at the beginning of maturation (defined by the presence of copulating specimens). Argulus foliaceus infects a much wider range of fish hosts. We showed that specialization of A. coregoni on salmonids does not necessarily result from incompatibility with other fishes, but could instead reflect higher sensitivity of oxygen depletion compared with A. foliaceus. Adult A. coregoni may meet these demands by attaching to salmonids, the typical inhabitants of well-aerated waters. Young parasites of both species showed little host specificity and attached mainly to fishes with higher body reflectivity. In host choice experiments, A. coregoni of 4–5 mm length preferred salmonids (rainbow trout) to cyprinids (roach) irrespective of the type of fish host, on which it had been previously grown in the laboratory. We suggest that such an innate ontogenetic shift in host preference maintains the major part of the parasite population on its principal host, ensuring successful reproduction within suitable habitats.

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Deutschlander, Mark E., Danielle K. Greaves, Theodore J. Haimberger, and Craig W. Hawryshyn. "Functional mapping of ultraviolet photosensitivity during metamorphic transitions in a salmonid fish, Oncorhynchus mykiss." Journal of Experimental Biology 204, no. 14 (July 15, 2001): 2401–13. http://dx.doi.org/10.1242/jeb.204.14.2401.

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SUMMARY Ultraviolet visual sensitivity appears to be reduced and, possibly, lost during smoltification in anadromous populations of salmonid fishes. Similar changes occur in non-anadromous salmonids over a mass range that is associated with smoltification in their anadromous conspecifics. However, in sexually mature adult salmonids, ultraviolet-sensitive cones are present in the dorso-temporal retina, suggesting that ultraviolet sensitivity (i) may be regained with sexual maturity or (ii) might never be completely lost. Both smoltification and the transition to sexual maturity are regulated, in part, by the hormone thyroxine. Thyroxine treatment of juvenile Oncorhynchus mykiss results in precocial developmental changes that mimic smoltification, including a reduction of ultraviolet sensitivity. However, whether loss of ultraviolet sensitivity in O. mykiss or in other species of salmonids is complete during normal development (or in response to thyroxine treatment) is unclear. In the present study, we have ‘mapped’ topographically ultraviolet photosensitivity during natural and hormone-induced smoltification. Thyroxine-treated O. mykiss juveniles and anadromous steelhead O. mykiss smolts were examined for ultraviolet visual sensitivity by recording compound action potentials from the optic nerve. By selectively illuminating either the dorsal or the ventral retina, we have shown that the reduction of ultraviolet sensitivity occurs primarily in the ventral retina in both groups of fish. Ultraviolet sensitivity remains intact in the dorsal retina.

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Gowan, Charles, Michael K. Young, Kurt D. Fausch, and Stephen C. Riley. "Restricted Movement in Resident Stream Salmonids: A Paradigm Lost?" Canadian Journal of Fisheries and Aquatic Sciences 51, no. 11 (November 1, 1994): 2626–37. http://dx.doi.org/10.1139/f94-262.

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Gerking (1959. Biol. Rev. 34: 221–242) proposed a theory about the restricted movement of stream fishes that may be considered a paradigm in salmonid biology. The restricted movement paradigm (our term) hold that resident stream salmonids are sedentary. Numerous studies have supported the restricted movement paradigm, but nearly all have relied on the recapture of marked fish from the same areas in which they were released, an approach we believe is biased against detecting movement. We found substantial movement of trout in streams in Colorado and Wyoming using two-way weirs and radio telemetry. A review of the research on Lawrence Creek, Wisconsin, also showed that movement was important in the response of the trout population to habitat enhancement. Movement of resident stream fish has profound implications for research (e.g., measuring production and habitat models) and management (e.g., habitat enhancement, special regulations, and stocking hatchery fish). Methods capable of detecting fish movement could be incorporated into many studies to assess its importance in systems of interest. New theories and experiments are needed to understand the mechanisms that cause stream salmonids to move.

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Morton, Alexandra B., and Rob Williams. "First Report of a Sea Louse, Lepeophtheirus salmonis, Infestation on Juvenile Pink Salmon, Oncorhynchus gorbuscha, in Nearshore Habitat." Canadian Field-Naturalist 117, no. 4 (October 1, 2003): 634. http://dx.doi.org/10.22621/cfn.v117i4.834.

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High infestation rates of the Sea Louse (Lepeophtheirus salmonis) have been reported on juvenile salmonids in Europe since 1989; however, this species has not been reported on juvenile Pacific salmonids until now. Magnitude of Sea Lice infestation was examined in 2001 on juvenile Pink Salmon (Oncorhynchus gorbuscha) migrating through a British Columbia archipelago. On average, the 751 juvenile Pink Salmon sampled weighed 2.25 g (± 0.039 SE), were infected with 11.3 (± 0.41 SE) Sea Lice per fish and 6.1 (± 0.24SE) Sea Lice per gram host weight. Fully 75.0% of fish were infected at loads equivalent to or higher than the lethal limit reported for much larger Sea Trout (Salmo trutta) post-smolts. Abundance (Kruskal-Wallis statistic = 100.95, p<0.0001) and intensity (KW= 70.05, p<0.0001) of lice, and mean number of lice/g host weight (K-W= 112.23, p<0.0001) were significantly higher in juvenile Pink Salmon in close proximity to salmon farms, than in Pink Salmon distant from salmon farms.

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Klinge, M. "Fish Migration via the Shipping Lock at the Hagestein Barrage: Results of an Indicative Study." Water Science and Technology 29, no. 3 (February 1, 1994): 357–61. http://dx.doi.org/10.2166/wst.1994.0134.

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In the Dutch part of the Rhine many hydraulic works (sluices, barrages, etc.) are situated which are considered to be barriers for upstream fish migration. Because of intensive shipping these works are always combined with big shipping locks. Until recently no data were available concerning fish migration via these locks. This was studied in the river Lek at the Hagestein barrage. Due to the short length of the study period and few recaptured salmonids (salmon, sea trout, rainbow trout) no conclusive evidence about the effects of the shipping lock on salmonid migration was obtained. However, the results do suggest that the Hagestein barrage complex forms a serious barrier for upstream migration of salmonids. Several other fish species on the other hand were observed to migrate through the lock. Therefore, depending on target species and management goals, the presence of shipping locks should be taken into account when considering improving fish migration possibilities.

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Chang, Chin-I., Yong-An Zhang, Jun Zou, Pin Nie, and Christopher J. Secombes. "Two Cathelicidin Genes Are Present in both Rainbow Trout (Oncorhynchus mykiss) and Atlantic Salmon (Salmo salar)." Antimicrobial Agents and Chemotherapy 50, no. 1 (January 2006): 185–95. http://dx.doi.org/10.1128/aac.50.1.185-195.2006.

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ABSTRACT Further to the previous finding of the rainbow trout rtCATH_1 gene, this paper describes three more cathelicidin genes found in salmonids: two in Atlantic salmon, named asCATH_1 and asCATH_2, and one in rainbow trout, named rtCATH_2. All the three new salmonid cathelicidin genes share the common characteristics of mammalian cathelicidin genes, such as consisting of four exons and possessing a highly conserved preproregion and four invariant cysteines clustered in the C-terminal region of the cathelin-like domain. The asCATH_1 gene is homologous to the rainbow trout rtCATH_1 gene, in that it possesses three repeat motifs of TGGGGGTGGC in exon IV and two cysteine residues in the predicted mature peptide, while the asCATH_2 gene and rtCATH_2 gene are homologues of each other, with 96% nucleotide identity. Salmonid cathelicidins possess the same elastase-sensitive residue, threonine, as hagfish cathelicidins and the rabbit CAP18 molecule. The cleavage site of the four salmonid cathelicidins is within a conserved amino acid motif of QKIRTRR, which is at the beginning of the sequence encoded by exon IV. Two 36-residue peptides corresponding to the core part of rtCATH_1 and rtCATH_2 were chemically synthesized and shown to exhibit potent antimicrobial activity. rtCATH_2 was expressed constitutively in gill, head kidney, intestine, skin and spleen, while the expression of rtCATH_1 was inducible in gill, head kidney, and spleen after bacterial challenge. Four cathelicidin genes have now been characterized in salmonids and two were identified in hagfish, confirming that cathelicidin genes evolved early and are likely present in all vertebrates.

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Price, M. H. H., A. Morton, and J. D. Reynolds. "Evidence of farm-induced parasite infestations on wild juvenile salmon in multiple regions of coastal British Columbia, Canada." Canadian Journal of Fisheries and Aquatic Sciences 67, no. 12 (December 2010): 1925–32. http://dx.doi.org/10.1139/f10-105.

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Salmon farms are spatially concentrated reservoirs of fish host populations that can disrupt natural salmonid host–parasite dynamics. Sea lice frequently infect farm salmon and parasitize sympatric wild juvenile salmonids, with negative impacts on survival in Europe and Pacific Canada. We examined louse parasitism of wild juvenile chum salmon ( Oncorhynchus keta ) and pink salmon ( Oncorhynchus gorbuscha ) from three salmon farming regions in British Columbia (Finlayson, Broughton Archipelago, and Georgia Strait). We compared sites of low and high exposure to farms and included an area without farms (Bella Bella) to assess baseline infection levels. Louse prevalence and abundance were lowest and most similar to natural baseline levels at low-exposure sites and highest at high-exposure sites in all farm regions. A significantly greater proportion of the lice were Lepeophtheirus salmonis at high-exposure sites. Exposure to salmon farms was the only consistently significant factor to explain the variation in prevalence data, with a secondary role played by salinity. Our results support the hypothesis that salmon farms are a major source of sea lice on juvenile wild salmon in salmon farming regions and underscore the importance of using management techniques that mitigate threats to wild stocks.

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48

Kolanowski, Wojciech. "Salmonids as Natural Functional Food Rich in Omega-3 PUFA." Applied Sciences 11, no. 5 (March 9, 2021): 2409. http://dx.doi.org/10.3390/app11052409.

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Salmonids are valuable fish in the human diet due to their high content of bioactive omega-3 very long-chain polyunsaturated fatty acid (VLC PUFA). The aim of this study was to assess the omega-3 VLC PUFA content in selected salmonid fish present on the food market regarding whether they were farm-raised or wild. It was assumed that farm-raised fish, by eating well-balanced feed enriched with omega-3 PUFA, might contain omega-3 VLC PUFA in levels similar to that of wild fish. Fat content, fatty acid composition and omega-3 VLC PUFA content in fish fillets were measured. Farm-raised salmon from Norway, wild Baltic salmon, farm-raised rainbow trout and brown trout were bought from a food market whereas wild trout (rainbow and brown) were caught alive. The fat content in fish ranged from 3.3 to 8.0 g/100 g of fillet. It was confirmed that although wild salmonid fish contain 10–25% more omega-3 VLC PUFA in lipid fraction, the farm-raised ones, due to the 60–100% higher fat content, are an equally rich source of these desirable fatty acids in the human diet. One serving (130 g) of salmonid fish fillets might provide a significant dose of omega-3 VLC PUFA, from 1.2 to 2.5 g. Thus, due to very high content of bioactive fatty acids eicosapentaenoic (EPA), docosapentaenoic (DPA) and docosahexaenoic (DHA) in their meat, salmonid fish currently present on the food market, both sea and freshwater as well as wild and farm-raised, should be considered as natural functional food.

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49

Long, Amy, and Simon R. M. Jones. "Piscirickettsia salmonis shedding and tissue burden, and hematological responses during cohabitation infections in chum Oncorhynchus keta, pink O. gorbuscha and Atlantic salmon Salmo salar." PLOS ONE 16, no. 3 (March 5, 2021): e0248098. http://dx.doi.org/10.1371/journal.pone.0248098.

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Background Salmonid rickettsial septicemia is an emergent and geographically widespread disease of marine-farmed salmonids caused by infection with the water-borne bacterium Piscirickettsia salmonis. Very little is known about the route, timing, or magnitude of bacterial shedding from infected fish. Methodology/principal findings A cohabitation challenge model was used to assess shedding from chum Oncorhynchus keta, pink O. gorbuscha and Atlantic salmon Salmo salar. Infections in donor fish were established by intraperitoneal injection of P. salmonis. Naïve recipients were cohabitated with donor fish after which cumulative percent morbidity and mortality (CMM) was monitored, and bacterial burdens in kidney and in tank water were measured by qPCR. All donor fish died with mean days-to-death (MDD) among species ranging from 17.5 to 23.9. Among recipients, CMM ranged from 42.7% to 77.8% and MDD ranged from 49.7 to 56.4. In each trial, two peaks of bacterial DNA concentrations in tank water closely aligned with the MDD values of donor and recipient fish. Bacterial tissue burden and shedding rate, and plasma physiological parameters were obtained from individual donors and recipients. Statistically significant positive correlations between the shedding rate and P. salmonis kidney burden were measured in donor pink and in donor and recipient chum salmon, but not in donor or recipient Atlantic salmon. In Atlantic salmon, there was a negative correlation between kidney bacterial burden and hematocrit, plasma Ca++ and Mg++ values, whereas in infected chum salmon the correlation was positive for Na+ and Cl- and negative for glucose. Conclusions A dependency of bacterial shedding on species-specific patterns of pathogenesis was suggested. The coincidence of bacterial shedding with mortality will inform pathogen transmission models.

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Lamon III, E. Conrad, and C. A. Stow. "Sources of variability in microcontaminant data for Lake Michigan salmonids: statistical models and implications for trend detection." Canadian Journal of Fisheries and Aquatic Sciences 56, S1 (November 30, 1999): 71–85. http://dx.doi.org/10.1139/f99-211.

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Variability in Lake Michigan salmonid microcontaminant data may arise from differences in contaminant concentrations in the water column, fat content, diet, age, location, and species-specific factors. Polychlorinated biphenyl (PCB) concentrations for salmonids in Lake Michigan have been determined for fish collected from a wide variety of locations and sizes for each of five species. Lake managers and policy makers wishing to evaluate trends in these concentration data must either remove this variability before trend assessment or leave it and settle for less statistical power for identifying the underlying time trend. Classification and regression trees (CART) have proven to be a useful tool for identifying nonlinear patterns of variability in these data and portraying them graphically. We used CART to study patterns of variability in PCB concentrations in five species of Lake Michigan salmonids, using data collected from 1972 to 1994 by both the Michigan and Wisconsin Departments of Natural Resources. For most of the species studied here, length was the major source of variability, followed by location.

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Journal articles on the topic 'Salmonids'

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