Reconstructing the life histories of fish has been a challenging problem for fisheries biologists. Unlike terrestrial organisms, the aquatic environments fish inhabit make direct observations difficult. Traditionally, fisheries biologists have tracked fish using unique fin clips, tagging, telemetry, and use of food dyes that mark bony parts of fish that can be viewed using UV lighting. However, fin clipping requires a lot of man power and time, tags can be lost, telemetry can be expensive, time consuming, and only reveals what a few fish in a population have done, and food dyes may not work only to be revealed a year or more later when fish are sampled. The discovery that the ear bones, otoliths, of fish can be used to reliably provide ages and that they record daily information about the water chemistry of a fish’s environment has advanced our ability to easily and inexpensively answer questions concerning life history movement patterns, natal origins, and even differentiating fish populations within a watershed.
These revelations have been guided by advances in elemental analysis that have revealed tight correlations between elemental water chemistry and the elemental chemistry measured in a fish’s otolith. Elemental water signatures are driven by geomorphology, particularly the type and age of the bedrock in a drainage or watershed. When fish move between tributaries or from main stem rivers into tributaries, as is the case with fish that migrate for spawning or in juveniles that drift or disperse down steam, and encounter waters with contrasting elemental signatures, a record of these movements is permanently recorded in a fish’s otolith. Advances in our abilities to measure the isotope ratios of these elements in otoliths and water as well as advances in sampling equipment, i.e. lasers, have exponentially increased the inferences biologists can make into describing fish life histories.
Gallery
Wyoming Game & Fish fisheries biologists clip fins on Yellowstone cutthroat trout to mark individuals as having originated in a hatchery
Otolith microchemistry reveals that this trout was stocked from a hatchery into Dead Indian Creek. Using this technique we can assess whether further stockings will be needed or if natural reproduction is occurring that will support this fishery
Recently, illegally introduced walleye were discovered by anglers and Wyoming Game & Fish biologists. Using otolith microchemistry we have determined the potential source, timing, and status of these walleye
Otolith microchemistry reveals two of the founding fish originated in one of two nearby reservoirs and that many of the fish were born in Buffalo Bill Reservoir
Often overlooked for Wyoming’s cold water fisheries, the Bighorn River in northern Wyoming is home to many warm water sport fish species
To support and restore a Shovelnose Sturgeon fishery, Wyoming Game & Fish biologists have been stocking juvenile sturgeon in the Bighorn River. To assess the success of their efforts, I am using fin ray microchemistry, similar to otolith microchemistry, to determine if sturgeon are naturally reproducing or if the fish are of hatchery origin
Fin ray analysis allows for the release of the fish, unharmed.
Results from this project will inform fisheries biologist how successful restoration efforts have been and how much stocking will be needed to support the persistence of this species and continued angler opportunities
Fisheries biologists also employ tags with unique numbers to identify individual fish
Fisheries biologists are always looking for new techniques to identify the origins of fish (hatchery vs wild) to assess the success of stocking efforts. New techniques use elemental signatures permanently recorded in fish otoliths, earbones seen on each side of the brain, to identify the natal origins of fish and even reconstruct life history movement patterns
This cross-section of a burbot otolith reveals alternating light and dark bands that correspond to summer and winter seasons. Elemental information in the fishes environment, water, is recorded in the layers of this otolith that are laid down daily. Accumulating layers over the life of a fish allow us to reconstruct life history information
This otolith from a 1 year old Burbot reveals daily growth bands visible in the darker regions
Burbot are a species of conservation concern in Wyoming. We are using otolith microchemistry to differentiate populations, reconstruct movement patterns, and determine natal origins
Otolith microchemistry reveals large differences between populations throughout the Wind River watershed
We are now using this data to understand the origins of Burbot entrained in the Wyoming Canal during the irrigation season. The Wyoming Canal removes up to 70% of the water in the Wind River during the irrigation season and is believed to entrain significant numbers of Burbot.
We are using this same technique to determine if Yellowstone Cutthroat trout stocked in Dead Indian Creek are naturally reproducing following a restoration project
Reports & Publications
Project Publications
Burbot in the Wind River drainage. View PDF
Project Reports
2010 Annual Report. View PDF
Contact
Scott A. Carleton, PhD
Wyoming Cooperative & Wildlife Research Unit
Dept. 3166, 1000 E. University Avenue
Laramie, WY 82070
[email protected]
cell: (307) 399-4711
David Zafft, Fish Managment Coordinator
Wyoming Game & Fish Department
528 S. Adams
Laramie, WY 82070
[email protected]
office: (307) 745-4046
Project Lead
Scott Carleton has been a postdoctoral research scientist in the Cooperative Fish and Wildlife Research Unit at the University of Wyoming since 2009. His research interests are in applied fish and wildlife ecology. His current work utilizes stable isotope microchemistry of water and fish otoliths to reconstruct movement patterns, differentiate populations, and determine the natal origins for native sport fish in Wyoming.
Timeline
This project began in July, 2009 and will be completed June, 2012
Funding & Partners
Wyoming Game & Fish Department