Factors affecting Long-term Stream Habitat Condition in Tongass National Forest, AlaskaTime can appear to stand still in Southeast Alaska’s Tongass National Forest, where streams supporting valuable anadromous and resident fish populations course through ancient stands of spruce, hemlock, and cedar. However, anthropogenic activities are contributing to dynamic change in northern forested ecosystems despite their remote location. Increasingly complex legacies of timber harvest which began in the Tongass in 1947 and climate change is causing transitions from snow to rain dominated hydrologies that may increase vulnerability of fishes to events such as winter floods. We are assessing long-term datasets of stream habitat conditions to 1) understand the natural range of habitat variability, 2) elucidate legacies of watershed management, and 3) anticipate changes due to ongoing effects of climate change across spatial management units.
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Movement Ecology of a Southern Range-Edge Lake Sturgeon Population
Lake Sturgeon were extirpated from much of the southern portion of their range by the early 1900's due to overharvest and habitat modification. We used telemetry to investigate spatial, temporal, and ontogenetic variation in movement by individuals to help inform reintroduction stocking and habitat management efforts to aid in species recovery. Hydrologic alterations by dams and availability of deepwater habitats as coolwater refugia may be important considerations in changing river environments.
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Population dynamics and Vital Rates of Shovelnose Sturgeon in the Cedar and Des Moines rivers
Commercial harvest demand for Shovelnose Sturgeon roe ("hackleback caviar") has grown in response to collapsing stocks of Eurasian sturgeon. In Iowa, every spring large aggregations of Shovelnose Sturgeon congregate on rocky shoals in the Cedar and Des Moines rivers in Iowa to spawn. Mark-recapture surveys for Shovelnose Sturgeon have been conducted at these sites since 2008. However, these long-lived slow growing fish are incredibly hard to age using traditional methods such as counting otolith annuli (bottom right photo). We are exploring how advancements in mark-recapture models can provide improved estimates of sex and age-specific survival, longevity, residency, and return rates that will help managers at the Iowa DNR and other agencies better manage Shovelnose Sturgeon populations sustainably.
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Natal Origin of Bigheaded Carp in the Upper Mississippi River |
We are using cutting-edge techniques to analyze the chemical signatures of otolith cores to infer the natal origins of Silver Carp of the upper Mississippi River. Natal origin of individual age classes will be analyzed to determine the interannual variability in natal origin relative to environmental factors, and a semi-passable barrier (LD 19) in the upper Mississippi River.
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