Amy Burgess and Dr. Dennis Shiozawa, Department of Biology
The cutthroat trout (Oncorhynchus clarki) is a member of the Salmonid family native to the western North America. Brook trout (Salvelinus fontinalis) is also a member of the salmonid family but a native to eastern North America, but has been introduced into many areas in western North America due to its popularity as a game fish. Observations of the invasion of nonnative brook trout (Salvelinus fontinalis) have often resulted in the replacement of cutthroat trout (Oncorhynchus clarki). While this is the case the underlying reasons for this replacement remain largely unknown (Peterson, 2004). Studies have been conducted looking at ecological relationship of the two species, factors such as recruitment, survival, emigration, immigration and abundance (Peterson, 2004 & Shepard, 2004). The results of these studies concluded that more research is needed on the potential influences of ecological factors on this specific invasion. These questions need to be answered for the benefit of those who wish to protect and conserve stream populations of cutthroat trout (Shepard, 2004).
The purpose of my research was/is to study the life histories of brook trout. While research has been done on the ecological aspects of the invasion of nonnative brook trout replacing cutthroat trout, I wanted to explore the possibility that life histories could be the bigger more determining factor in this specific invasion.
The purpose of looking at the life histories of these two species was to determine if one species has an advantage over the other. In my research I have looked at the age, size (length and weight), and sexual maturity of the fish. With this information I would be able to determine if there is an advantage for one species over the other. What I was looking for was the relationship between sexual maturity and size of the fish. This would be advantageous to whichever species reproduces at a smaller size, because they will be more likely to reproduce at least once before being removed from their environment (fished).
Research and data has been collected for cutthroat trout. My research included looking at two populations of brook trout from the Uinta Basin and I am currently processing their life histories. I have taken measurements of weight and length. I have determined the age of the fish by growth rings found on the otoliths of the fish. Sexually maturity was determined by gonad extraction and the weight of gonads to total weight ratios and length to gonad weight ratios.
My original project was to be completed by the end of Summer 2008, but I was delayed in my research due to an internship opportunity in the Pacific Northwest, were I was able to represent BYU well through my research. As one of eight chosen nationally to participate in this program I gained a lot of knowledge about research, presenting at conferences and preparing for a future based in research. Although I was not in Provo to work on my brook trout research I did find some time during my January-July internship to do literature searches for my ORCA research.
After I returned at the end of the summer Dr. Shiozawa and I decided to expand my project. With the results I have gathered, my project has been expanded to encompass research done throughout the United States. I have started gathering data from around the country to compile a data set of life histories of brook and cutthroat trout.
With this data set I plan on publishing in a scientific journal my findings on the similarities found around the country. These similarities being the stunting of cutthroat trout due to the introduction of brook trout. We are in the process of putting together the data set as well as the beginnings of the manuscript. We hope to have a manuscript out for review by the middle of Winter semester 2009 (end of February, beginning of March). I also hope to present a local conferences with my research.
With this data I will compare the rates of sexual maturity between brook and cutthroat trout. With the invasion of brook trout into the streams where native cutthroat trout numbers are decreasing we hope to determine, with the data from this expanded research, that the brook trout are reproducing at a younger age or a smaller length. This would explain why the number of cutthroat are decreasing with the invasion of brook trout and could explain why ecological studies have not been very successful. These are the results that have been found around a large percentage of the nation and I predict we will find similar results in the Uinta regions we are currently looking at.
I am grateful for the opportunity to do research here at BYU. Having this ORCA grant was extremely helpful, without the grant I would not have been able to spend as much time as I have on my research. I would also like to thank my mentor, Dr. Dennis Shiozawa, with his help and guidance I have been able to work through this project and its changes. I would also like to thank the extra help from the DKS lab, without their help, second opinions would have been hard to come by during this solo project. Thanks guys!
Sources
- Donald, David B & Alger, David J (1989) EVALUATION OF EXPLOITATION AS A MEANS OF IMPROVING GROWTH IN A STUNTED POPULATION OF BROOK TROUT. North American Journal of Fisheries Management: Vol. 9, pp.177-183
- Hadley, Michael J (2007) EFFECTS OF FORAGE FISH PRESENCE ON THE DIET AND GROWTH OF BROWN TROUT IN STREAMS. Brigham Young University Thesis
- McGee, Michael N (1998) LIFE HISTORY OF COLORADO RIVER CUTTHROAT TROUT (ONCORHYNCHUS CLARKI PLEURITICUS) AND THE EFFECTS OF INTROGRESSION WITH RAINBOW TROUT (O. MYKISS) AND YELLOWSTONE CUTTHROAT TROUT (O. C. LEWISI). Brigham Young University Thesis
- Peterson DP, Fausch KD, White GC (2004) POPULATION ECOLOGY OF AN INVASION: EFFECTS OF BROOK TROUT ON NATIVE CUTTHROAT TROUT. Ecological Applications: Vol. 14, No. 3 pp. 754 -772
- Shepard, Bradley B (2004) FACTORS THAT MAY BE INFLUENCING NONNATIVE BROOK TROUT INVASION AND THEIR DISPLACEMENT OF NATIVE WESTSLOPE CUTTHROAT TROUT IN THREE ADJACENT SOUTHWESTERN MONTANT STREAMS. North American Journal of Fisheries Management: Vol. 24, No. 3 pp. 1088-1100