Mortality patterns during the freshwater production phase of salmonids in Norway

Gåsnes, Siri Kristine; Oliveira, Victor Henrique Silva de; Gismervik, Kristine; Ahimbisibwe, Ashley; Tørud, Brit; Jensen, Bogi Bech

doi:10.1111/jfd.13522

Cited by 10 publications

(9 citation statements)

References 37 publications

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“…Pathogen screening of 27 pink salmon in Gulf of Alaska (GoA) during the winter of 2019 demonstrated that they are carriers of several opportunistic and pathogenic species (Deeg et al, 2022). The opportunistic bacterium Candidatus Branchiomonas cysticola seems to be ubiquitous and highly prevalent in pink salmon in the Pacific and native salmonids in Norway (Garseth, Florø‐Larsen, et al, 2020; Gåsnes et al, 2019; Lennox et al, 2020). The bacterium has also been detected in pink salmon in Norway (Fjær, 2019).…”

Section: Synthesizing Pink Salmon Knowledge Between Pacific and Atlanticmentioning

confidence: 99%

Prospects for the future of pink salmon in three oceans: From the native Pacific to the novel Arctic and Atlantic

et al. 2023

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While populations of other migratory salmonids suffer in the Anthropocene, pink salmon (Oncorhynchus gorbusca Salmonidae) are thriving, and their distribution is expanding both within their natural range and in the Atlantic and Arctic following introduction of the species to the White Sea in the 1950s. Pink salmon are now rapidly spreading in Europe and even across the ocean to North America. Large numbers of pink salmon breed in Norwegian rivers and small numbers of individuals have been captured throughout the North Atlantic since 2017. Although little is known about the biology and ecology of the pink salmon in its novel distribution, the impacts of the species' introduction are potentially highly significant for native species and watershed productivity. Contrasts between pink salmon in the native and extended ranges will be key to navigating management strategies for Atlantic nations where the pink salmon is entrenching itself among the fish fauna, posing potential threats to native fish communities. One key conclusion of this paper is that the species' heritable traits are rapidly selected and drive local adaptation and evolution. Within the Atlantic region, this may facilitate further establishment and spread. The invasion of pink salmon in the Atlantic basin is ultimately a massive ecological experiment and one of the first examples of a major faunal change in the North Atlantic Ocean that is already undergoing rapid changes due to other anthropogenic stressors. New research is urgently needed to understand the role and potential future impacts of pink salmon in Atlantic ecosystems.

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Section: Synthesizing Pink Salmon Knowledge Between Pacific and Atlanticmentioning

confidence: 99%

Prospects for the future of pink salmon in three oceans: From the native Pacific to the novel Arctic and Atlantic

et al. 2023

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“…The availability of monthly data on fish mortality during the freshwater phase presents an opportunity for further investigations that integrate fish from hatcheries into the SyS system. However, the feasible use of this data is hindered by the lack of proper identification of fish that belongs to specific cohorts, which arises from common practices in hatcheries involving grading and movement of fish between tanks [57]. For diseases that can occur at any point during seawater production, alarm delays are a consequence in younger fish.…”

Section: Discussionmentioning

confidence: 99%

Exploring Options for Syndromic Surveillance in Aquaculture: Outbreak Detection of Salmon Pancreas Disease Using Production Data from Norwegian Farms

Oliveira,

Dórea,

Dean

et al. 2024

Transboundary and Emerging Diseases

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Syndromic surveillance (SyS) is an important tool for early warning and monitoring of health in human and animal populations, but its use in aquaculture has been limited. Our study objective was to design a SyS system for Atlantic salmon aquaculture and to evaluate its performance in detecting pancreas disease (PD) outbreaks caused by salmonid alphaviruses on farms. We defined SyS outbreak alarms as cases where monthly farm mortality exceeded predefined cutoffs or deviated significantly from expected values based on predictive generalized linear models. These models were trained for each salmon production area in Norway, using data from 2014 to 2017. The outcome variable was fish mortality per farm-month, and input variables were production and environmental predictors, as well as an offset for the number of fish at risk. We also added autoregressive components to explain temporal dependency within fish cohorts. Subsequently, data from 2018 to 2021 was used to parameterize and validate the SyS system’s performance against the current national PD surveillance program, which relies on routine farm-screening tests using molecular techniques and reports of clinical findings. The study covered 19,119 farm-months, involving 1,618 fish cohorts. The performance of our SyS system varied across production areas, with sensitivity ranging from 80.5% to 87.4% and a false alarm rate of 45.3%–53.2%. The absence of alarms was usually observed in farms that were truly negative for PD, i.e., a negative predictive value range of 81.2%–94.0%. The median time for alarms being raised was either in the same month as the current PD surveillance program or 1 month prior or after it. Our results indicate that the SyS system is a valuable tool for monitoring mortality on salmon farms, but alarms are unspecific if evaluated against an individual disease (PD). Increasing the frequency and granularity of mortality reporting might improve the SyS system’s performance.

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“…Low thiamine in steelhead is an additional stressor on already struggling populations. A major factor that affects fish survival in hatcheries is infectious disease [ 26 , 46 ]. Thiamine deficiency contributes to T-cell-dependent and -independent immune dysfunction [ 47 ], as well as lowered WBC bactericidal activity and the mitogenesis of fish cells in vitro [ 48 ].…”

Section: Discussionmentioning

confidence: 99%

Thiamine Supplementation Improves Survival and Body Condition of Hatchery-Reared Steelhead (Oncorhynchus mykiss) in Oregon

Reed

Rowland

Krajcik

et al. 2023

Veterinary Sciences

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Early rearing of steelhead (Oncorhynchus mykiss) in Oregon hatcheries is often problematic; fry can become emaciated and die during the period between hatch and first feed. Thiamine (vitamin B1) deficiency has caused early mortality in salmonids; however, the thiamine status of Oregon’s steelhead populations is unknown, to date. Of the 26 egg samples from three Oregon hatcheries in 2019, 20 (77%) had thiamine levels < 10 nmol/g, and 13 of those samples (50%) had levels <6.5 nmol/g, suggesting the thiamine deficiency of adult, female steelhead. To investigate if thiamine deficiency was causally related to fry survival, females were injected with buffered thiamine HCl 50 mg/kg prior to spawning; additionally, a subset of eggs were supplemented via bath treatment with thiamine mononitrate (1000 ppm) at spawning. Cumulative fry mortality at 8 weeks post-hatch from thiamine-injected females was 2.9% compared to 13.8% mortality of fry without thiamine supplementation. Fry treated only with the thiamine via bath as eggs had a mortality rate of 6.9%. There were no additional improvements for the survival of fry from injected females that also received a thiamine bath. Furthermore, condition factors were greater in thiamine-supplemented fry than in those that received no thiamine. These data identify thiamine deficiency in Oregon steelhead and suggest supplementation with thiamine can mitigate early rearing mortality.

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Mortality patterns during the freshwater production phase of salmonids in Norway

Cited by 10 publications

References 37 publications

Prospects for the future of pink salmon in three oceans: From the native Pacific to the novel Arctic and Atlantic

Prospects for the future of pink salmon in three oceans: From the native Pacific to the novel Arctic and Atlantic

Exploring Options for Syndromic Surveillance in Aquaculture: Outbreak Detection of Salmon Pancreas Disease Using Production Data from Norwegian Farms

Thiamine Supplementation Improves Survival and Body Condition of Hatchery-Reared Steelhead (Oncorhynchus mykiss) in Oregon

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