Case Studies in Fisheries Conservation and Management: Applied Critical Thinking and Problem Solving
Case 3: A Float Trip on the Bad River, South Dakota: How Will Cyprinid Distributions Change from Headwaters to Mouth?
The Bad River (Figure 3.1) flows through ruggedly beautiful country in the semi-arid region of western South Dakota. The watershed area for the Bad River is 8,044 km 2, and mean annual rainfall in the basin is 41–46 cm. For the years 1929–2000, average annual discharge was 4.9 m 3/sec, with annual means ranging from as low as 0.2 m 3/sec to as much as 34 m 3/sec (Milewski 2001). Your instructor will take you on a photographic “float trip” of the river, from its headwaters to its confluence with the Missouri River (a linear distance of approximately 120 km “as the crow flies”).
As you travel from the headwaters to the mouth of the Bad River, consider both the changes in habitat as well as the influence of the Missouri River as you near the river mouth. You will be asked to predict expected patterns in abundance of two different minnows, the fathead minnow and flathead chub (Figure 3.2), from the headwaters to the mouth. We will provide a graph showing the changes in abundance for the two species. However, you will need to identify which trend line is most likely associated with each of the two species.
You will first need to research life history information for both the fathead minnow and flathead chub. What is their maximum size and maximum age? What type of habitat do they prefer? What are their food habits? What are their environmental tolerances for water quality, turbidity, water velocity, etc.? What are their interrelationships with predators? Sources of information can include both books at your library, or internet resources.