| 1. |
- Bowman, Jennifer, et al.
(författare)
-
Evaluation of the reliability of indicators of consciousness during CO2 stunning of rainbow trout and the effects of temperature
- 2020
-
Ingår i: Aquaculture Research. - : Hindawi Limited. - 1355-557X .- 1365-2109. ; 51, s. 5194-5202
-
Tidskriftsartikel (refereegranskat)abstract
- A two-part experiment was conducted to determine whether visual indicators of consciousness such as equilibrium, eye-roll reflex and ventilation are reliable for evaluating whether CO2 stunning of rainbow trout (Oncorhynchus mykiss) is humane. In part 1, the time taken until the loss of visual indicators in rainbow trout during CO2 stunning was monitored under field conditions at 14, 8 and 2 degrees C. Here, we clearly demonstrate that it takes longer for visual indicators to disappear as temperature decreases, with significant differences in the time taken until the loss of equilibrium between 2 and 14 degrees C, and significant differences between all temperatures in the time taken until the loss of eye-roll reflex and ventilation. In part 2, rainbow trout were equipped with external non-invasive electrodes for recording EEG prior to, and following, CO2 stunning to assess the presence or absence of visually evoked responses (VERs), which are indicative of brain function and sensibility. The resulting EEG recordings during CO2 stunning at 10 degrees C demonstrated a poor relationship between visual indicators of consciousness and loss of sensibility, as VERs were present up to 3.5 min after ventilation was lost and up to 6.5 min after the fish lost equilibrium. Collectively, these results show that cold-water temperatures prolong the time taken until loss of consciousness and that visual indicators are insufficient for determining when sensibility is lost in rainbow trout during CO2 stunning.
|
|
| 2. |
- Brijs, Jeroen, et al.
(författare)
-
Effects of electrical and percussive stunning on neural, ventilatory and cardiac responses of rainbow trout
- 2025
-
Ingår i: AQUACULTURE. - 0044-8486 .- 1873-5622. ; 594
-
Tidskriftsartikel (refereegranskat)abstract
- From an ethical standpoint, it is imperative that rainbow trout (Oncorhynchus mykiss) are humanely slaughtered, which entails that they are rendered unconscious immediately by a stunning method and remain so until death. The efficacy of electrical stunning following dewatering (i.e., in-air electrical stunning at intensities of 50 to 920 mA and durations of 5 to 30 s) and percussive stunning, both advocated as humane stunning and/or killing methods, are evaluated here for this species via the presence or absence of visually evoked responses (VERs). In addition, ventilatory and cardiac responses were evaluated to elucidate the physiological basis for the lethality of both methods. While the present study was unable to determine the capability of in-air electrical stunning to induce immediate unconsciousness, our findings revealed that irreversible stuns were induced by both in-air electrical stunning (i.e., similar to 25 to 70% of individuals did not recover VERs across the various combinations of stunning intensities and/or durations) and percussive stunning (i.e., similar to 100% of individuals did not recover VERs). The efficacy of in-air electrical stunning for permanently abolishing VERs was marginally, but significantly, impacted by stun intensity (i.e., explained 8% of the variation). Furthermore, due to substantial inter-specific variability and a limited sample size, significant impacts of stun intensity and/or duration on the recovery of VERs in reversibly stunned individuals were not detected in the present study (i.e., VERs recovered between <0.5 to 28.8 min). Further investigation is therefore necessary before in-air electrical stunning can be endorsed as a standalone humane slaughter method for rainbow trout. This includes determining its capacity to induce immediate unconsciousness, as well as to identify additional factors that could be modified or enhanced to improve its efficacy. Furthermore, since death following in-air electrical stunning likely entails a prolonged process involving ventilatory failure, hypoxemia, and subsequent vital organ malfunction, rather than immediate cardiac arrest or central nervous system failure, the sequential use of methods such as percussive stunning is recommended to safeguard the welfare of rainbow trout during slaughter.
|
|
| 3. |
- Brijs, J., et al.
(författare)
-
Prevalence and severity of cardiac abnormalities and arteriosclerosis in farmed rainbow trout (Oncorhynchus mykiss)
- 2020
-
Ingår i: Aquaculture. - : Elsevier BV. - 0044-8486 .- 1873-5622. ; 526
-
Tidskriftsartikel (refereegranskat)abstract
- Cardiovascular disease may pose a major threat to the health and welfare of farmed fish. By investigating a range of established cardiovascular disease indicators, we aimed to determine the prevalence, severity and consequences of this affliction in farmed rainbow trout (Oncorhynchus mykiss) from an open cage farm in the Baltic Sea, an open cage farm in a freshwater lake, and a land-based recirculating aquaculture system. We also aimed to identify environmental, anthropogenic and physiological factors contributing towards the development of the disease. The majority of trout possessed enlarged hearts with rounded ventricles (mean height:width ratios of 1.0–1.1 c.f. ~1.3 in wild fish) and a high degree of vessel misalignment (mean angles between the longitudinal ventricular axis and the axis of the bulbus arteriosus of 28–31 °c.f. ~23° in wild fish). The prevalence and severity of coronary arteriosclerosis was also high, as 92–100% of fish from the different aquaculture facilities exhibited coronary lesions. Mean lesion incidence and severity indices were 67–95% and 3.1–3.9, respectively, which resulted in mean coronary arterial blockages of 19–32%. To evaluate the functional significance of these findings, we modelled the effects of arterial blockages on coronary blood flow and experimentally tested the effects of coronary occlusion in a sub-sample of fish. The observed coronary blockages were estimated to reduce coronary blood flow by 34–54% while experimental coronary occlusion adversely affected the electrocardiogram of trout. Across a range of environmental (water current, predation), anthropogenic (boat traffic intensity, hatchery of origin, brand of feed pellets) and physiological factors (condition factor, haematological and plasma indices), the hatchery of origin was the main factor contributing towards the observed variation in the development of cardiovascular disease. Therefore, further research on the effects of selective breeding programs and rearing strategies on the development of cardiovascular disease is needed to improve the welfare and health of farmed fish. © 2020 The Authors
|
|
| 4. |
|
|
| 5. |
|
|
| 6. |
- Gunnarsson, Stefan, et al.
(författare)
-
Systematic mapping of research on farm-level sustainability in finfish aquaculture
- 2020
-
Ingår i: Sustainability. - : MDPI AG. - 2071-1050. ; 12:23
-
Tidskriftsartikel (refereegranskat)abstract
- The sustainability of future finfish aquaculture needs to be improved to meet global environmental challenges. Global fish aquaculture production has expanded significantly recently, due to the increased demand for fish for human consumption. Therefore, it is important to mitigate challenges to the sustainability of the sector, such as pollution and depletion of natural resources. In this study, we systematically mapped the scientific literature on farm-level sustainability in fish aquaculture. The concept of sustainability was considered holistically, covering its economic, environmental and social dimensions, each consisting of a range of different aspects that may contradict or reinforce each other. Literature published between January 2000 and August 2020 with the geographical focus on Europe, Northern America and Australia–New Zealand was included. The search resulted in a total of 287 hits, but after the exclusion of articles that did not match the scope, only 17 papers remained for the systematic mapping. Of these, five papers covered all three dimensions of sustainability. Economic sustainability was addressed in 10 papers, environmental sustainability in 13 papers and social sustainability in 12 papers. This systematic mapping provides an important foundation for discussions and prioritisations of future actions to increase knowledge on farm-level sustainability in finfish aquaculture.
|
|
| 7. |
|
|
| 8. |
|
|
| 9. |
|
|
| 10. |
|
|
