Progress 06/10/11 to 09/09/12
Outputs
Target Audience: Target audiences include local governments, fisheries managers, fish biologists, hatcheries, researchers, educators, students, and thegeneral public. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?
Nothing Reported
How have the results been disseminated to communities of interest? A draft paper has been submitted to the Grant County Public Utility District, the sponsor of this research. What do you plan to do during the next reporting period to accomplish the goals?
Nothing Reported
Impacts
What was accomplished under these goals?
Objective 1: It is critical that water could be collected and maintained in a manner that will ensure that it retains its odor qualities. We explored this question by testing the stability of water under different storage regimes, utilizing the electro-olfactogram, a technique that measures the olfactory responses of the salmon’s olfactory epithelium. We found that White River water collected in January could be held for seven days at 40° C, 50° C, or frozen (-20°C) and thawed without altering the olfactory signature of the water. Different sites and water collection periods might produce different results, however, and more research examining storage protocols and the appropriate length of storage or water replacement will be necessary. This suggests that under the proper conditions water can be collected, transferred and stored for use in embryonic imprinting. Initial attempts to freeze dry and then reconstitute White River water altered the olfactory signal. A second concern associated with transferring natural stream water into a central hatchery for embryo imprinting is the potential for this practice to introduce pathogens and expose potentially critical fish populations to disease risk. In many cases, embryonic salmon are initially reared in pathogen-free well water but where stream water is utilized, it is typically treated with ultraviolet (UV) light to kill pathogens in the water. In many cases, transferring natural stream water into a central hatchery for embryonic imprinting would be prohibited unless that water was treated to remove pathogens. Such treatments have the potential for altering the chemical make-up of the water and, therefore, the olfactory signature of the stream water. To address this question, we again utilized the cross-adaptation technique using fresh White River water that was either treated with UV light to remove pathogens or left untreated. Interestingly, in this case UV treatment apparently altered the chemical nature of White River water because UV-treated water elicited a different olfactory response than untreated water. However, it is unclear from this experiment whether the overall odor qualities are conserved enough such that salmon can still distinguish this water as White River water. To test whether UV treatment might alter some aspects of the chemical qualities of the water without altering the chemical nature enough so that salmon no longer recognized treated water as “White River”, we conducted a separate behavioral experiment. In these experiments, we exploited the observation that embryonic salmon learn and, as emergent fry, tend to be attracted to water they were incubated in. For these experiments, steelhead embryos were incubated in Carnes Creek water at the Oregon Hatchery Research Center near Alsea, Oregon and then tested for attraction to different waters as emergent fry. To test the effect of UV treatment on the perception of the odor qualities of this water, we tested whether emergent fry would choose untreated Carnes Creek water over UV-treated Carnes creek water in a two-choice maze. We hypothesized that if UV treatment altered the attractive qualities of the water, we might expect more fish to choose the untreated arm of the maze but we observed no difference in attraction to the two waters. These results do not directly demonstrate that UV-treatment did not alter the odor qualities that allow fry to distinguish Carnes Creek water but are consistent with that conclusion. Again, further study of the effects of UV treatment and other sterilization techniques on odor qualities are warranted if embryonic imprinting is employed in sensitive areas. Objective 2: For embryonic imprinting to be a useful and effective tool, a number of practical concerns must be addressed before the widespread use of this protocol could be adopted. Whether managers use transported natural water, artificial odorants or artificial natural waters, we believe that embryonic imprinting may provide an important new management tool for reducing negative interactions between hatchery and wild salmon populations, facilitating recovery of endangered populations and recolonization of recovered habitat, and generally increasing the homing precision of hatchery-reared fish. Each hatchery program is unique in terms of its program goals, infrastructure and logistic realities, and geographic complexities and the utility of embryonic imprinting approach and the specific application or these tools must be developed on a case-by case basis. Embryonic imprinting is already being employed as part of a kokanee salmon recovery program in Lake Sammamish Washington (LSKWG 2012) and would be particularly appropriate for a number of conservation and supplementation hatchery programs in the Northwest. The principles underlying this strategy are well-founded in our understanding of salmon biology and life history strategy but full-scale tests of this approach within an existing hatchery program will be required to confirm the utility of embryonic imprinting. Objective 3: A draft paper has been completed.
Publications
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