2004 Lake Sturgeon Research
Why is genetics important to Lake Sturgeon rehabilitation and management?By Kristin Bott, graduate student, Michigan State University
A common theme throughout population biology is the importance of diversity. In natural environments, diversity in form and function allows populations to adapt to changing environments. Diversity can be observed and quantified in many ways: physically (e.g. body size, shape, color, etc), genetically, or behaviorally. This diversity is measured at several biological levels, including variation among populations, among individuals within populations, and also within individuals.
Examination of diversity among populations can be used to answer many different questions, including the degree to which populations are reproductively isolated. This is especially important for managers considering population supplementation (e.g. stocking) when trying to rehabilitate a numerically depressed population. For example, if you have 3 rivers in close proximity, two with a large number of fish and one with very few individuals, which of the two healthy rivers should you use to stock the population with few individuals? Examining the genetic characteristics of the two (larger) candidate "donor" populations will help you decide. If one donor population is genetically more similar to the population with few fish, then use of that population as a donor source may be a wiser choice.
The ability of fish to adapt to their environment can also be directly tied to genetics. Over time, populations become better suited to their particular environment. This ties to the importance of population structure. An example of population structure in sturgeon can be seen in Pat DeHaan's graduate work at Michigan State University (MSU) on lake sturgeon throughout the Great Lakes, including the Black Lake population. Pat found that there are genetic differences among populations. These differences could be tied to both lake basin and geographic distance. Generally speaking, the larger the genetic differences are between populations, the longer populations have been separated reproductively, and the greater the possibility that genetically based adaptations will have accumulated.
Diversity within a population is also important, especially when considering long-term persistence, related to issues such as inbreeding. Inbreeding can lead to a loss of adaptability (lower genetic diversity may compromise an individuals ability to responding to environmental changes), but also in the accumulation of undesirable genetic traits. An example of this is domestic purebred dogs, which can have a much higher incidence of some health problems (e.g. dysplasia) than a mixed breed, which has a larger gene pool from which to draw.
Within-population diversity is one of the areas we are studying for Black Lake sturgeon. We are going to be examining the degree of relatedness among the spawning adults and their offspring sampled at different life stages. We're interested in how diversity changes over time. For example, is there a high level of diversity present in the eggs, less so in the offspring? Are there large numbers of adults contributing to offspring that are can be expected to be recruited into the next generation, or does diversity (average relatedness among individuals) stay constant, even when the number of individuals may decrease due to predation or other sources of mortality (e.g. tens of thousands of eggs -> thousands of larvae -> hundreds of juvenile fish)?
The Black Lake population is unique. Because of the accessibility of adults and offspring of all sizes and ages, we are able to design critical experiments and tailor observations that will provide answers to pressing management questions. While a portion of our research is being conducted in a lab far removed from the shores of Black Lake, genetics can be a powerful tool. The collection of genetic data compliments other activities being conducted with adults and larvae in the river, and can highlight many things that cannot be addressed by fish watching alone. The answers to these questions, and many more, will help us better understand the life history and ecology of sturgeon. Sound management must be founded on good science.
If our goal is to restore sturgeon populations in Black Lake and elsewhere in Michigan, we need to be armed with the best possible information. Use of cutting edge technology, including genetics is important. The collaborations among Sturgeon for Tomorrow, the Michigan Department of Natural Resources, and Michigan State University have been extremely important to providing continuity in our ongoing programs.
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