共查询到20条相似文献，搜索用时 15 毫秒
1.
Sean M. Cochran Seth Ricker Colin Anderson Sean P. Gallagher Darren M. Ward 《Fisheries Management and Ecology》2019,26(2):165-171
Obtaining reliable estimates of marine survival is essential for understanding anadromous salmon population dynamics. Two common approaches to estimating marine survival are (a) dividing abundance of returning adult salmon abundance by abundance of smolts from the same cohort, or (b) tagging a portion of the migrating smolts and estimating the return rate of tagged adults. This study compared these two approaches to estimating marine survival for coho salmon, Oncorhynchus kisutch (Walbaum), across multiple years in three California streams. Abundance‐based survival estimates were higher than tag‐based estimates; average estimates for the two techniques differed from 1.5‐fold to 7.4‐fold across streams. One likely cause for these divergent estimates is migration of juveniles from natal habitat before smolt trapping begins, resulting in an underestimate of smolt abundance and an overestimate of marine survival rate for the abundance‐based method. Estimates of marine survival obtained from abundance estimates and tag returns are not directly comparable. 相似文献
2.
Tessa J. Frost Ellen M. Yasumiishi Beverly A. Agler Milo D. Adkison Megan V. McPhee 《Fisheries Oceanography》2021,30(1):99-109
Hatcheries release >4.5 billion juvenile Pacific salmon (Oncorhynchus spp.) into the North Pacific Ocean annually, raising concerns about competition with wild salmon populations. We used retrospective scale analysis to investigate how the growth of chum salmon (O. keta) from western Alaska is affected by the abundance of chum salmon from Japanese hatcheries and wild pink salmon (O. gorbuscha) from the Russian Far East. Over nearly five decades, the growth of Kuskokwim River chum salmon was negatively correlated with the abundance of Japanese hatchery chum salmon after accounting for the effects of sex and spring/summer sea‐surface temperature in the Bering Sea. An effect of wild eastern Kamchatka pink salmon abundance on the growth of Kuskokwim River salmon was detectable but modest compared to the intraspecific competitive effect. A decrease in Japanese hatchery chum salmon releases in 2011–2013 was not associated with increased growth of Bering Sea chum salmon. However, the abundance of wild chum salmon from the Russian Far East increased during that time, possibly obscuring reduced competition with hatchery chum salmon. Our results support previous evidence that chum salmon are affected by intraspecific competition, and to a lesser extent interspecific competition, in the North Pacific, underscoring that the effects of salmon hatchery production transcend national boundaries. 相似文献
3.
Michael J. Malick 《Fisheries Oceanography》2020,29(3):265-275
Environmental change is occurring at unprecedented rates in many marine ecosystems. Yet, environmental effects on fish populations are commonly assumed to be constant across time. In this study, I tested whether relationships between ocean conditions and productivity of North American sockeye salmon (Oncorhynchus nerka) stocks have changed over the past six decades. Specifically, I evaluated the evidence for non‐stationary relationships between three widely used ocean indices and productivity of 45 sockeye salmon stocks using hierarchical Bayesian models. The ocean indices investigated were the Pacific Decadal Oscillation (PDO), North Pacific Gyre Oscillation (NPGO), and sea surface temperature (SST). I found partial support for time‐varying salmon–ocean relationships. Non‐stationary relationships were strongest for the NPGO and weaker for the SST and PDO indices. Productivity–NPGO correlations tended to shift gradually over time with opposite trends for stocks in British Columbia (B.C.) and western Alaska; for B.C. stocks, the NPGO correlations shifted from significantly negative prior to 1980 to significantly positive after 1990, whereas for western Alaska stocks, the correlations shifted from positive to negative. Productivity–SST correlations showed declining trends for B.C. and Gulf of Alaska stocks, that is, correlations became more negative (B.C.) or less positive (Gulf of Alaska) over time. For the PDO, correlations weakened during the 1980s for western Alaska and B.C. stocks. Overall, these results provide evidence for time‐varying relationships between salmon productivity and environmental conditions over six decades, highlighting the need to recognize that historical responses of salmon populations to environmental change may not be indicative of future responses. 相似文献
4.
H. A. Urke T. Kristensen J. B. Ulvund J. A. Alfredsen 《Fisheries Management and Ecology》2013,20(6):544-552
Migration timing, speed, survival and effects of environmental parameters on migration, between wild and hatchery produced Atlantic salmon, Salmo salar L., smolts in the River Lærdalselva were studied. Hatchery‐reared (n = 40) and wild pre‐smolts (n = 40) were tagged with acoustic tags, and an array of receivers along the migration route was deployed. In all, 77 and 85% of the fish from the two groups, respectively, were recorded as migrating smolts, that is, predation rate and/or numbers of fish opting to remain in the river were low. Hatchery‐reared smolts showed a migration pattern, speed and migration route similar to wild smolts, even though the time period between river release and onset of migration was relatively short. Both groups of smolt showed high migration speed through both the river and the fjord compared with other studies. 相似文献
5.
Catherine Bradley Suresh Andrew Sethi Joshua Ashline Jonathon Gerken 《Ecology of Freshwater Fish》2017,26(4):695-706
In this study, we examined summer and fall freshwater rearing habitat use by juvenile coho salmon (Oncorhynchus kisutch) in the quickly urbanising Big Lake drainage in south‐central Alaska. Habitat use was assessed by regressing fish count data against habitat survey information across thirty study sites using generalised linear mixed models. Habitat associations were examined by age‐0 and age‐1+ cohorts separately, providing an opportunity to compare habitat use across different juvenile coho salmon life stages during freshwater rearing. Regression results indicated that the age‐0 cohorts were strongly associated with shallow, wide stream reaches with in‐stream vegetation, whereas age‐1+ cohorts were associated with deeper stream reaches. Furthermore, associations between fork length and habitat characteristics suggest cohort‐specific habitat use patterns are distinct from those attributable to fish size. Habitat use information generated from this study is being used to guide optimal fish passage restoration planning in the Big Lake drainage. Evidence for habitat use partitioning by age cohort during freshwater juvenile rearing indicates that pooling age cohorts into a single “juvenile” stage for the purposes of watershed management may mask important habitat use dynamics. 相似文献
6.
The environmental and host‐associated bacterial microbiota of Arctic seawater‐farmed Atlantic salmon with ulcerative disorders 
下载免费PDF全文
下载免费PDF全文 C Karlsen K F Ottem Øyvind Jakobsen Brevik M Davey H Sørum H C Winther‐Larsen 《Journal of fish diseases》2017,40(11):1645-1663
The Norwegian aquaculture of Atlantic salmon (Salmo salar L.) is hampered by ulcerative disorders associated with bacterial infections. Chronic ulceration may provide microenvironments that disturb the normal microbial biodiversity of external surfaces. Studying the composition of microbial communities in skin ulcers will enhance our understanding of ulcer aetiology. To achieve this, we tested marine farmed Atlantic salmon and sampled the base and edge of ulcers at the end of winter (April) and end of summer (September), in addition to skin mucus of healthy individuals. In order to assess microbiota associated with the host and obtain insight into the environmental ecology, we also sampled sea water, the sediment layer underneath the farm facility and the distal intestine of Atlantic salmon. The skin microbiota of Atlantic salmon was different from that of the surrounding water. Residential Tenacibaculum and Arcobacter species persistently dominated the cutaneous skin and ulcer mucus surfaces of Atlantic salmon during both winter and summer periods. The intestinal microbiota was dominated by Mycoplasma with an increase in Aliivibrio and Alcaligenes abundance in the intestine of fish with ulcerative disorder at the end of winter. These findings suggest the presence of resilient microbes in the mucus surfaces of Atlantic salmon. 相似文献
7.
Forecasting adult salmon abundance is problematic when the number of observations is small relative to the number of potential explanatory variables. Machine learning and other non‐traditional techniques employ algorithms designed to prevent model overfitting. Data from 18 coho salmon, Oncorhynchus kisutch (Walbaum), and seven Chinook salmon, Oncorhynchus tschawytscha (Walbaum), populations on the Oregon coast were used to evaluate the forecast performance of artificial neural networks, elastic net, least absolute shrinkage and selection operator, principal component regression (PCR) and ridge regression (RR) compared to several more traditional techniques. In general, the non‐traditional modelling techniques evaluated in this study performed similarly to the traditional techniques with the exception of sibling regression. This suggests that they have merit for improving actual predictions. Among the non‐traditional techniques, PCR resulted in the lowest prediction error for the coho salmon populations, and RR predicted Chinook salmon returns most accurately. The techniques explored are not an easy solution to a difficult problem. Spurious conclusions about the processes that generate salmon returns still may result as evidenced by the inclusion of an unrelated variable in many of the non‐traditional models. 相似文献
8.
9.
Competitive interactions among multiple non‐native salmonids and two populations of Atlantic salmon 下载免费PDF全文
下载免费PDF全文 Competitive interactions with non‐native species can have negative impacts on the conservation of native species, resulting in chronic stress and reduced survival. Here, juvenile Atlantic salmon (Salmo salar) from two allopatric populations (Sebago and LaHave) that are being used for reintroduction into Lake Ontario were placed into semi‐natural stream tanks with four non‐native salmonid competitors that are established in Ontario streams: brown trout (S. trutta), rainbow trout (Oncorhynchus mykiss), Chinook salmon (O. tshawytscha) and coho salmon (O. kisutch). Brown trout and rainbow trout reduced the survival and fitness‐related traits of Atlantic salmon, whereas Chinook salmon and coho salmon had no impact on these traits. These data support theories on ecological niche overlap and link differences in observed aggression levels with competitive outcomes. Measurements of circulating hormones indicated that the Atlantic salmon were not chronically stressed nor had a change in social status at the 10‐month time point in the semi‐natural stream tanks. Additionally, the Sebago population was better able to coexist with the non‐native salmonids than the LaHave population. Certain populations of Atlantic salmon may thus be more suitable for some environments of the juvenile stream phase for the reintroduction into Lake Ontario. 相似文献
10.
Genome‐wide association analysis of salmon lice (Lepeophtheirus salmonis) resistance in a North American Atlantic salmon population 下载免费PDF全文
下载免费PDF全文 Christina M Rochus Melissa K Holborn Keng P Ang J A K Elliott Brian D Glebe Steven Leadbeater J J Tosh Elizabeth G Boulding 《Aquaculture Research》2018,49(3):1329-1338
Our objective was to detect single nucleotide polymorphisms (SNPs) associated with resistance to the salmon louse in the Saint John River aquacultural population of North American Atlantic salmon using estimated breeding values (EBVs) and 6K genotypes from the parent‐generation and lice count phenotypes from the challenged, but ungenotyped, offspring‐generation. In 2011 and 2012, we challenged recent smolts with approximately 100 copepodids each. Fish were euthanized once the lice reached the chalimus stages and lice count, sex, tank and salt water weight were recorded. We used a multiple trait model to estimate breeding values for the parent‐generation using their own fresh water weights and the salt water weights and lice counts of the offspring‐generation. Salmon lice count heritability for untransformed and transformed data was 0.17 and 0.29 respectively. Two different genome‐wide association study methods were compared: (i) forward multiple linear regression and (ii) a mixed linear model using principal components to correct for population stratification as implemented in the egscore function of GenABEL. The two methods detected different SNPs located on different chromosomes. The multiple regression method incorporated 70 SNPs found on chromosomes 2, 7, 9, 12, 14, 15, 21, 22, 1p/23, 24. Many SNPs entered into the forward multiple regression are likely to be false positives from not correcting for the observed population stratification and cryptic relatedness. In contrast, the mixed linear model identified only two SNPs, one on chromosome 1p/23 (6.9%) and one on chromosome 1q (6.1%) consistent with louse‐resistance being a quantitative trait. 相似文献
11.
Abstract – The objectives of this study were, first, to assess the usefulness of otolith microstructure analysis to examine winter size‐selective mortality of young‐of‐the‐year (YOY) Atlantic salmon and, secondly, to validate various hypotheses relating to the dynamics of two populations with different winter survival. By examining otolith microstructure, we back‐calculated body size at hatching and at emergence of YOY salmon sampled in fall 2000 and in early summer 2001 on the Petite Cascapédia River and the Bonaventure River (Québec, Canada). The results of the study did not reveal any size‐selective mortality of YOY salmon in the Petite Cascapédia River, while in the Bonaventure River, size‐selective mortality of the smaller individuals of the cohort was detected. This case study allowed not only a better comprehension of the population dynamics of those rivers but demonstrated the usefulness of otolith analysis to detect winter size‐selective mortality under a natural environment. 相似文献
12.
The effect of ultrasound exposure during controlled infection with salmon lice, Lepeophtheirus salmonis, has been studied. Salmon were placed in tanks with salmon lice copepodids for 1 hr, while simultaneously being exposed to sound frequencies of 9.3, 21 or 54 kHz. The sound transducers were operated at maximum power levels, and the 9.3 kHz transducer generated the highest sound level (220.6 dB). Only the group exposed to 9.3 kHz displayed a significant reduction in louse infestation. However, the observed effect of ultrasound was relatively small, and in a practical implementation in sea cages, the sound intensity will be lower than that used in the experiments. It is also possible that the observed reduction in infestation is due to ultrasonic cavitation effects, which are only present at a very short range from the ultrasound source. We therefore do not consider ultrasound a feasible method for preventing attachment of salmon lice copepodids on salmon in cage farms. 相似文献
13.
Accumulation of 14C in various tissues and organs was studied in three different groups of 0.8‐kg Atlantic salmon Salmo salar force‐fed with 14C1‐glucose in order to evaluate if metabolism of glucose depended on adaptation to dietary carbohydrate level. The salmon had been fed diets supplemented with 0, 100 and 200 g maize dextrin kg?1 for 10 months before the experiment. The fish were force‐fed 6.65 × 104 Bq of 14C1 glucose kg?1 BW, in gelatin capsules. Fish for analysis were obtained 16 h later. 14C was measured in blood plasma, gill, kidney, liver and white muscle, and in lipid extract of liver. The liver contained most 14C, followed by heart, blood plasma, gill and liver lipid extract, while kidney and muscle contained the least 14C per gram or millilitre tissue. The muscle contained most radioactivity, on an estimated total tissue basis, followed by liver, blood plasma, gill, liver lipid extract, kidney and heart tissue. Thirty‐eight per cent of the orally administered 14C was recovered in the salmon adapted to the diet without dextrin after 16 h. This was significantly (P < 0.05) higher than the 30% and 32% recovered in the salmon adapted to diets with 10% and 20% dextrin. This effect on adaptation to dietary dextrin level in glucose uptake or metabolism was supported by a trend (P < 0.10) toward higher radioactivity per gram or millilitre of each individual tissue in the fish adapted to the diet without dextrin, when compared with the other two adaptation regimes. 相似文献
14.
Survival and behaviour of Atlantic salmon smolts passing a run‐of‐river hydropower facility with a movable bulb turbine 下载免费PDF全文
下载免费PDF全文 E. B. Thorstad T. B. Havn S. A. Sæther L. Heermann M. A. K. Teichert O. H. Diserud M. Tambets J. Borcherding F. Økland 《Fisheries Management and Ecology》2017,24(3):199-207
Downstream migration of radio‐tagged Atlantic salmon smolts, Salmo salar L., was studied in the Kinzig, Germany, to examine effects of passing a run‐of‐river hydropower station with a movable bulb turbine. Immediate mortality for smolts passing the power station was low (3%–6%), probably facilitated by a curved rack in front of the turbine and the possibility to pass over it. Mortality in the impounded stretch above the power station was also low (1.5% extra mortality compared to a control stretch). The combined mortality due to hydropower was 5%–8%, excluding delayed effects. Most smolts followed the main flow passing through the turbine area (94%). Only few used a fishway (4%) or a nearby millstream (2%). Migration speed was slowed down at the power station, but the passage only caused a short delay (average/median 8.6/1.3 hr). However, even low mortality and short delays at several power stations and reservoirs may have considerable cumulative effects. 相似文献
15.
Sea lice are significant parasites of marine and brackish farmed fishes. Freshwater bathing is a potential control option against numerous sea lice species, although has been viewed as futile against those that are capable of tolerating freshwater for extended periods. By comparing freshwater survival times across host‐attached stages of Lepeophtheirus salmonis (Krøyer), a key parasite in Atlantic salmon farming, we show the first attached (copepodid) stage undergoes 96–100% mortality after 1 h in freshwater, whereas later attached stages can tolerate up to 8 days. Thus, regular freshwater bathing methods targeting the more susceptible attached copepodid stage may successfully treat against L. salmonis and potentially other sea lice on fish cultured in marine and brackish waters. 相似文献
16.
17.
Abstract – Decreases in body growth with increasing population density may be caused by reduced prey delivery rate. However, changes in food quality because of an increasing inclusion of suboptimal prey in the diet may also contribute to such effects. Here, we test for density‐dependent diet composition by creating spatial variation in Atlantic salmon young‐of‐the‐year (YOY) density in three replicate streams and obtain detailed information on individual positions (±1 m) and diet. Diet breadth with respect to prey size increased with increasing local density for the two most common prey types (Chironomidae and Ephemeroptera). For the largest prey type (Ephemeroptera), there was also an increase in mean prey size with increasing density, suggesting that YOY salmon preferentially utilise the smaller prey among those available. According to optimal foraging theory, changes in diet with increasing local density are likely to come at an energetic cost and hence may contribute to the commonly observed density‐dependent growth of juvenile salmonids. 相似文献
18.
Comparative pathogenesis of piscirickettsiosis in Atlantic salmon (Salmo salar L.) post‐smolt experimentally challenged with LF‐89‐like and EM‐90‐like Piscirickettsia salmonis isolates 下载免费PDF全文
下载免费PDF全文 M Rozas‐Serri R Ildefonso A Peña R Enríquez S Barrientos L Maldonado 《Journal of fish diseases》2017,40(10):1451-1472
19.
Influence of gear switching on recapture of Atlantic salmon (Salmo salar) in catch‐and‐release fisheries 下载免费PDF全文
下载免费PDF全文 Robert J. Lennox Ola H. Diserud Steven J. Cooke Eva B. Thorstad Frederick G. Whoriskey Øyvind Solem Torgeir B. Havn Ingebrigt Uglem 《Ecology of Freshwater Fish》2016,25(3):422-428
Anglers that release Atlantic salmon (Salmo salar) in recreational fisheries do so with the intention that the fish will survive and contribute to succeeding generations. In some instances, salmon that are released may be recaptured, but mechanisms associated with recapture are unclear. To test whether gear avoidance influences recapture rates, we analysed data from tagging programmes in major Norwegian Atlantic salmon fishing rivers to determine how frequently salmon were recaptured by different gear than that by which they were initially captured (i.e. gear switch). Among 339 salmon captured, externally tagged and released in 2012 and 2013, 46 (14%) were recaptured; 70% of these recaptured salmon exhibited gear switch. To test whether this gear switch percentage could be expected in the absence of gear avoidance, a simulation was conducted, which accounted for variation in catch probability among rivers and across time with different gear types based on comprehensive catch data. Each simulation step provided a simulated rate of gear switch under the null hypothesis of no gear avoidance. A distribution was generated, which described the probability that we would observe 70% gear switch. The simulated results indicated that this rate of gear switch was highly unlikely (P = 0.003) if recapture gear is assumed to be independent of initial capture gear, suggesting that salmon avoided familiar gear types. Changes to behaviour after release, including learned hook avoidance, may explain our observation of gear avoidance by recaptured salmon. 相似文献
20.
Knut Wiik Vollset Randi Ingebjørg Krontveit Peder A Jansen Bengt Finstad Bjørn Torgeir Barlaup Ove Tommy Skilbrei Martin Krkošek Pål Romunstad Arnfinn Aunsmo Arne J Jensen Ian Dohoo 《Fish and Fisheries》2016,17(3):714-730
Parasites can, in theory, have large impacts on the survival of fish populations. One method to evaluate such impacts on anadromous species is to apply manipulative field experiments in which parallel groups of antiparasitically treated and non‐treated fish are simultaneously released and then subsequently recaptured as returning adults. A systematic review and meta‐analysis on all such Norwegian studies on Salmo salar provided a data set for the time period 1996 to 2011 on 118 release groups comprising 657 624 fish released and 3989 recaptured. The overall risk ratio (RR) was estimated to be 1.18 (95% CI: 1.07–1.30). The effect varied strongly between groups, (Higgins I2 = 40.1%). Over 70% of this heterogeneity could be explained by the release location, time period and baseline survival. The most important predictor variable was baseline survival. In groups with low recapture in the control group (low baseline survival), the effect of treatment was high (RR = 1.7), while in groups with high recapture in the control group (high baseline survival), there was no effect of treatment (RR ~ 1.00). The most prevalent parasite in the region affected by the drugs administered was Lepeophtheirus salmonis. Hence, the meta‐analysis supports the hypothesis that L. salmonis contributes to the mortality of S. salar during outward migration. However, the effect of treatment was not consistent, but was evidently strongly modulated by other risk factors. The results suggest that the population‐level effects of parasites cannot be estimated independently of other factors affecting the marine survival of S. salar. 相似文献