The Evaluation of the Response of American Eels to Rapid Decompression

Hydropower dams are used throughout the world to generate electricity and dams can negatively affect fish, as they can hinder or block migration or be a source of injury and mortality during passage. When moving downstream, fish can pass through the turbines instead of other routes (e.g. spillway and juvenile bypass system)where there is a sudden decrease in pressure that can cause barotraumas, injuries from the changes in barometric pressure, (e.g., hemorrhaging, embolism, ruptured organs) due to internal gases expanding. To determine the response of American eels, Anguilla rostrate, to rapid decompression, testing was conducted in the Mobile Aquatic Barotrauma Laboratory (MABL) at PNNL’s Aquatic Research Lab between 6 June and 5 August 2016. In total, 105 eels were tested in MABL’s hyper/hypobaric chambers by simulating the rapid decompression experienced in turbines. Eels were acclimated to 25 feet depth and the nadir, lowest pressure the eels experienced, during the test was measured. This was done to determine the ratio of pressure change (RPC) the eels experienced during testing (i.e., acclimation pressure/nadir pressure). After exposure, the eels were held for two days to monitor survival before a necropsy was performed. There were only two mortalities observed (1.9%) in the study. Twenty-one fish were found to have non-fatal barotraumas. However, these injuries are fatal for other species (e.g., Chinook salmon). The maximum RPC for fish with injuries was 11.32, while the greatest RPC in the study was 19.66, and so further research is needed to determine if there is a RPC that will result in 100% mortality for this species. The results provide information that can be used in the design and operation of turbines to minimize mortality for fish that pass through

American eel resilience to simulated fluid shear associated with passage through hydroelectric turbines

American eel (Anguilla rostrata) populations have declined within their native range along the eastern coast of North America due to factors such as commercial fishing, habitat alteration, and dams. American eel are catadromous fish species, and high mortality rates (>40%) have been observed for freshwater life-stage adult eel passing downstream through hydropower turbines. Lacerations and sectioning of fish have been observed downstream of turbines and these injuries are commonly associated with direct contact with the turbine runner, whether through blade strike or pinching and grinding. Exposure to fluid shear may also be a source of injury, however, little is known about American eel susceptibility to this physical stressor. Eels are considerably flexible when compared to other fish species and lack other morphological characteristics that would make them susceptible to fluid shear, such as protruding eyes, large scales, and large operculum. European eel, which have previously been tested for susceptibility to fluid shear, were found to be resilient. To determine if American eel are also resilient to fluid shear, forty American eel were exposed to a water jet, simulating severe fluid shear (strain rate > 800 s−1) that fish may experience when passing downstream through turbines. No immediate or delayed (48 h) signs of injury were observed after exposure to severe fluid shear. Based on this study, and a previous study conducted on American eel susceptibility to barotrauma, the source of injury and mortality of American eel passing through turbines is likely attributed to blade strike or pinching and grinding

Injury and Mortality of Two Mekong River Species to Turbulent Shear Forces

Global hydropower development is one solution proposed to address an increase in energy needs. However, hydropower-related impacts on riverine ecology systems is not well understood. The Mekong River Basin (MRB) is one of the world’s largest waterways and is presently experiencing significant hydropower expansion. It is also one of the most biodiverse rivers; serving as home to many species that are blocked or hindered by the development of dams. One source of injury and mortality for downstream moving fishes is passage through the turbine environment where fishes may be exposed to a number of physical stressors (e.g., shear forces, rapid decompression, blade strike and turbulence). The current study sought to understand the susceptibility of blue gourami (Trichopodus trichopterus) and iridescent shark (Pangasianodon hypophthalmus) to shear forces. Fishes were exposed to an underwater jet with velocities up to 21.3 m/s (equating to strain rates of up to 1,185 s-1). Fish were assessed for behavioral effects, injuries, and mortality. Overall, it was determined that both species were susceptible to shear forces and the effects were more pronounced at higher strain rates. Gouramis were more susceptible than sharks. To minimize impacts on these species, shear forces within turbines should not exceed critical limits

American eel state of buoyancy and barotrauma susceptibility associated with hydroturbine passage

American eel are likely to encounter and pass through hydropower turbines, particularly during the downstream spawning migration, where exposure to stressors can potentially lead to injuries and mortality. Previous research has recovered dead eels downstream of hydropower facilities and, for some fish, injuries were easily attributed to blade strike; however, others showed no external signs of injury suggesting that other stressors, such as rapid decompression may be a potential source of mortality. For this research, yellow– and silver-phase American eel were held and allowed to acclimate to 172 kPa (absolute pressure) in hyper/hypobaric hydro-chambers for about 1 d. After acclimation, the state of buoyancy was determined prior to exposure to a rapid decompression simulating pressures encountered during hydroturbine passage. Fish were then examined for signs of barotrauma. Eel did not attain a state of neutral buoyancy but rather maintained negative buoyancy suggesting that eels, and possibly other benthic species, likely maintain a state of negative buoyancy to facilitate occupancy on or near the substrate. Additionally, eel were found to be resilient to rapid decompression, displaying no instantaneous mortality and minimal injuries, suggesting that barotrauma is not likely a major concern for American eel passing downstream through hydroturbines

Ten practical realities for institutional animal care and use committees when evaluating protocols dealing with fish in the field

Institutional Animal Care and Use Committee’s (IACUCs) serve an important role in ensuring that ethical practices are used by researchers working with vertebrate taxa including fish. With a growing number of researchers working on fish in the field and expanding mandates of IACUCs to regulate field work, there is potential for interactions between aquatic biologists and IACUCs to result in unexpected challenges and misunderstandings. Here we raise a number of issues often encountered by researchers and suggest that they should be taken into consideration by IACUCs when dealing with projects that entail the examination of fish in their natural environment or other field settings. We present these perspectives as ten practical realities along with their implications for establishing IACUC protocols. The ten realities are: (1) fish are diverse; (2) scientific collection permit regulations may conflict with IACUC policies; (3) stakeholder credibility and engagement may constrain what is possible; (4) more (sample size) is sometimes better; (5) anesthesia is not always needed or possible; (6) drugs such as analgesics and antibiotics should be prescribed with care; (7) field work is inherently dynamic; (8) wild fish are wild; (9) individuals are different, and (10) fish capture, handling, and retention are often constrained by logistics. These realities do not imply ignorance on the part of IACUCs, but simply different training and experiences that make it difficult for one to understand what happens outside of the lab where fish are captured and not ordered/purchased/reared, where there are engaged stakeholders, and where there is immense diversity (in size, morphology, behaviour, life-history, physiological tolerances) such that development of rigid protocols or extrapolation from one species (or life-stage, sex, size class, etc.) to another is difficult. We recognize that underlying these issues is a need for greater collaboration between IACUC members (including veterinary professionals) and field researchers which would provide more reasoned, rational and useful guidance to improve or maintain the welfare status of fishes used in field research while enabling researchers to pursue fundamental and applied questions related to the biology of fish in the field. As such, we hope that these considerations will be widely shared with the IACUCs of concerned researchers

Concurrent Sessions B: Case Studies of Passage at Dams - Passage Distributions and Federal Columbia River Power System Survival for Steelhead Kelts Tagged Above and at Lower Granite Dam

Steelhead (Oncorhynchus mykiss) populations have declined throughout their range in the last century and many populations, including those of the Snake River Basin are listed under the Endangered Species Act. The reasons for their decline are many, but include habitat loss and degradation, overharvest, and the construction of dams. Unlike Pacific salmon, which all die after they spawn, post-spawning steelhead (known as kelts) can migrate back to the ocean to feed and replenish their energy stores, then return to freshwater and spawn in subsequent years (known as iteroparity). However, it is estimated tha

Concurrent Sessions B: Columbia River Passage - Hydroturbine Passage Related Barotrauma Research in the Columbia River Basin: How Far Have We Come?

Within the past decades, most of the research related to hydroturbine passage has centered on seaward migrating juvenile salmonids. Throughout the years the techniques and technologies used to study barotrauma have evolved as have our understanding of the causal pathways. Tools, such as the Sensor Fish that are used to measure pressure changes fish are exposed to when passing turbines have also improved considerably. Research has also begun to be done on other fish types such as lamprey and sturgeon. This past research has led to a rethinking of the fundamental way that turbine survival studies are conducted and evaluated and how past research should be viewed. Having a comprehensive understanding of the effects of barotrauma in fish is increasingly important as the need to expand energy output of current hydropower facilities exists. This presentation will provide an overview of past, present and future research on hydroturbine passage and will detail stumbling blocks experienced upon the way and common misconceptions about turbine survival research

American eel resilience to simulated fluid shear associated with passage through hydroelectric turbines

American eel (Anguilla rostrata) populations have declined within their native range along the eastern coast of North America due to factors such as commercial fishing, habitat alteration, and dams. American eel are catadromous fish species, and high mortality rates (>40%) have been observed for freshwater life-stage adult eel passing downstream through hydropower turbines. Lacerations and sectioning of fish have been observed downstream of turbines and these injuries are commonly associated with direct contact with the turbine runner, whether through blade strike or pinching and grinding. Exposure to fluid shear may also be a source of injury, however, little is known about American eel susceptibility to this physical stressor. Eels are considerably flexible when compared to other fish species and lack other morphological characteristics that would make them susceptible to fluid shear, such as protruding eyes, large scales, and large operculum. European eel, which have previously been tested for susceptibility to fluid shear, were found to be resilient. To determine if American eel are also resilient to fluid shear, forty American eel were exposed to a water jet, simulating severe fluid shear (strain rate > 800 s−1) that fish may experience when passing downstream through turbines. No immediate or delayed (48 h) signs of injury were observed after exposure to severe fluid shear. Based on this study, and a previous study conducted on American eel susceptibility to barotrauma, the source of injury and mortality of American eel passing through turbines is likely attributed to blade strike or pinching and grinding