scholarly journals Does Vaterite Otolith Deformation Affect Post-Release Survival and Predation Susceptibility of Hatchery-Reared Juvenile Atlantic Salmon?

2021 ◽  
Vol 8 ◽  
Author(s):  
Aurélien Delaval ◽  
Martine Røysted Solås ◽  
Helge Skoglund ◽  
Anne Gro Vea Salvanes
Keyword(s):  
Atlantic Salmon ◽  
Salmo Trutta ◽  
Growth Traits ◽  
Survival Rates ◽  
Fish Length ◽  
Fish Welfare ◽  
Term Survival ◽  
Juvenile Atlantic Salmon ◽  
Predation Mortality ◽  
And Control

Sagittal otoliths are calcareous structures in the inner ear of fishes involved in hearing and balance. They are usually composed of aragonite; however, aragonite can be replaced by vaterite, a deformity which is more common in hatchery-reared than in wild fish. Vaterite growth may impair hearing and balance and affect important fitness-related behaviours such as predator avoidance. Captive rearing techniques that prevent hearing loss may have the potential to improve fish welfare and the success of restocking programmes. The aim of this study was to test the effect of structural tank enrichment on vaterite development in the otoliths of hatchery-reared juvenile Atlantic salmon Salmo salar, and to assess the effects of vaterite on immediate predation mortality and long-term survival after release into the wild. Fry were reared in a structurally enriched or in a conventional rearing environment and given otolith marks using alizarin during the egg stage to distinguish between the treatment groups. Otoliths were scrutinised for the presence and coverage of vaterite at 6, 13, and 16 weeks after start feeding, and the growth traits were measured for enriched and control fry when housed in tanks. In a subsequent field experiment, juveniles were released in the Rasdalen river (western Norway), and otoliths of enriched reared and control reared fry were scrutinised from samples collected immediately prior to release, from predator (trout Salmo trutta) stomachs 48 h after release and from recaptures from the river 2–3 months after release. Vaterite otoliths occurred as early as 6 weeks after start feeding in hatchery-reared S. salar. Vaterite occurrence and coverage increased with fish length. Enriched rearing had no direct effect on vaterite formation, but enriched reared fry grew slower than control fry. After release into the wild, fewer salmon fry with vaterite otoliths had been eaten by predators, and a higher proportion of fry with vaterite otoliths than those lacking vaterite were recaptured in the river 2–3 months after release. Contrary to expectations, this suggests that vaterite does not increase predation mortality nor reduce survival rates in the wild during the early life stages.

Prognostic selection and long-term survival analysis to assess overdiagnosis risk in lung cancer screening randomized trials

2020 ◽  
pp. 096914132092303
Author(s):  
Eugenio Paci ◽  
Donella Puliti ◽  
Francesca Maria Carozzi ◽  
Laura Carrozzi ◽  
Fabio Falaschi ◽  
...  
Keyword(s):  
Lung Cancer ◽  
Cancer Screening ◽  
Survival Rates ◽  
Lung Cancer Screening ◽  
Term Survival ◽  
Long Term Survival ◽  
And Control ◽  
Screening Trial

Objectives Overdiagnosis in low-dose computed tomography randomized screening trials varies from 0 to 67%. The National Lung Screening Trial (extended follow-up) and ITALUNG (Italian Lung Cancer Screening Trial) have reported cumulative incidence estimates at long-term follow-up showing low or no overdiagnosis. The Danish Lung Cancer Screening Trial attributed the high overdiagnosis estimate to a likely selection for risk of the active arm. Here, we applied a method already used in benefit and overdiagnosis assessments to compute the long-term survival rates in the ITALUNG arms in order to confirm incidence-excess method assessment. Methods Subjects in the active arm were invited for four screening rounds, while controls were in usual care. Follow-up was extended to 11.3 years. Kaplan-Meyer 5- and 10-year survivals of “resected and early” (stage I or II and resected) and “unresected or late” (stage III or IV or not resected or unclassified) lung cancer cases were compared between arms. Results The updated ITALUNG control arm cumulative incidence rate was lower than in the active arm, but this was not statistically significant (RR: 0.89; 95% CI: 0.67–1.18). A compensatory drop of late cases was observed after baseline screening. The proportion of “resected and early” cases was 38% and 19%, in the active and control arms, respectively. The 10-year survival rates were 64% and 60% in the active and control arms, respectively ( p = 0.689). The five-year survival rates for “unresected or late” cases were 10% and 7% in the active and control arms, respectively ( p = 0.679). Conclusions This long-term survival analysis, by prognostic categories, concluded against the long-term risk of overdiagnosis and contributed to revealing how screening works.

Temperature Selection of Juvenile Atlantic Salmon (Salmo salar) as Influenced by Various Toxic Substances

1976 ◽  
Vol 33 (8) ◽  
pp. 1722-1730 ◽  
Author(s):  
R. H. Peterson
Keyword(s):  
Atlantic Salmon ◽  
Salmo Salar ◽  
Toxic Substances ◽  
Term Survival ◽  
Preferred Temperature ◽  
Atlantic Salmon Salmo Salar ◽  
Juvenile Atlantic Salmon ◽  
Sodium Pentachlorophenate ◽  
Selection Of ◽  
Short Term Survival

Previous exposure to sodium pentachlorophenate (NaPCP), Guthion®, malathion, Dursban®, and Dibrom® lowered the preferred temperature for juvenile Atlantic salmon (Salmo salar) tested in a horizontal temperature gradient. Lindane, CuSO4, ZnSO4, CdSO4, Sevin®, heptachlor, and fenitrothion did not change the preferred temperature significantly. Comparison with other published results indicates that those substances that increase the preferred temperature are more toxic (based on relevant changes in 24-h LC50) at low temperatures and vice versa. It is suggested that such shifts in selected temperature may be of potential immediate, short-term, survival value to the fish.

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