Fall 2017: Problem Set 3 (DUE Oct 26; 50 points)

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1 ESS 445 Introduction to Fisheries Science and Management: Biology, Ecology, Management, and Conservation of North American Freshwater Fishes and Aquatic Ecosystems Fall 2017: Problem Set 3 (DUE Oct 26; 50 points) Lab 9 Oct 19, 2017 Pond Management and Fisheries Sampling Gear: Analysis Phase Chapter 16 (IFM) Chapter 6, 7, and 14 (Fisheries Techniques) Introduction and Objectives Small impoundments ( ac), variously referred to as ponds, farm ponds, lakes, and wetlands, are formed by diverting or collecting water then retaining it in excavated pits with dams. Most are privately created for a specific purpose, but all have multiple potential uses and users, especially public ponds. Farm ponds, for example, are important sources of water for livestock and irrigation. Ponds can also be created to attract water fowl for hunting. Other uses of ponds include boating, swimming, and raising ornamental fishes. Many ponds offer recreational sport fishing opportunities. The quality of fishing is often measured in terms of catch rate and catch size. Consequently, the fish populations in ponds often must be manipulated through stocking and harvest strategies to produce the angling experiences desired by the owner or user groups. The objective of this lab is to introduce you to the field of pond fisheries management (e.g., Neal and Willis 2012). We will focus on the typical scenario for a bass bluegill pond in northeastern North America. Specifically, we will assess the current status of a local pond focusing on the pond fish assemblage (rather than physical and chemical characteristics). In so doing, we will introduce additional fisheries sampling gear used to sample fishes in lentic waters. Furthermore, we will introduce sampling and statistical techniques to quantify the balance of pond fish assemblages and estimate the size of fish populations. Finally, you will have the chance to consider some of the attributes of the pond fish assemblage to evaluate the potential as a viable fishery. Specifically, you will consider various stocking and harvest options to improve upon or adjust current conditions of the pond fish assemblages if needed to meet the desired outcomes for sustaining or enhancing angling experiences. Thus, this lab and its write-up constitutes what could be largely considered the essential components of a pond fish management plan that could be communicated to the owners of the pond when finished (hint, hint: something like this would make a great capstone project). Methods (review) We sampled fish populations in a pond on the property of Woodcock Valley Community Park in McConnellstown with seines, fyke nets, and angling. Each fish was measured (total length) and weighed. We also marked each fish captured with a fin clip; during our second outing we recorded the number of recaptures. This mark-recapture data will be used in a subsequent lab on population estimation later in the semester. In addition, we measured water quality of the pond 1

2 with a YSI (ph, conductivity, temperature, D.O., TDS) and with Hach kits (alkalinity, acidity, Ca hardness, total hardness). We will also take water samples back to the analytical lab on campus for determination of dissolved constituents (Al, Ca, Fe, Mg, Mn in mg/l) and other parameters (alkalinity mg/l as CaCO3, acidity mg/l as CaCO3, conductance µs/cm, and sulfates mg/l). (Not done in 2017) Analysis for this lab Work with a partner to discuss and solve the problems (but your written answers below must be your own unique responses to the questions). Use the accompanying dataset we collected to complete the following analyses and calculate assessment indices from the fisheries survey data. See class notes for equations. Use a spreadsheet to do calculations by writing formulas to carry out computations. Interpret the meaning of each index you calculate. Fish Populations and Assemblage. Calculate the following indices. 1. F:C ratio Consider F to be all sunfish and crappie (and minnows/shiners if we catch any). 2. Y:C ratio First, estimate the size of a forage fish small enough to be eaten after determining the average size of all individuals that are carnivores (the largemouth bass and pickerel). Report what you believe this size to be. 3. AT Use 45g for sunfish, 140 for crappie, 180 g for largemouth bass, 260 g for white perch, and 230 g for channel cats or bullheads. Do it separately for each species 4. PSD Calculate for each game species with adequate sample size (BG, LMB, crappie) See page 534 in text (or your class notes) for minimum stock and quality size 5. RSD (PSD-P and M) Calculate for each game species with adequate sample size (BG, LMB, crappie) Use preferred and memorable size designations 6. Wr (largemouth bass, bluegill, crappie, pickerel) To find Ws use the equations in the book LMB: Log10Ws = * Log10 L BG: Log10Ws = * Log10 L (Hillman 1982) Channel Cats: Log10Ws = * Log10 L Report the average Wr for the populations 2

3 Literature cited Hillman, W.P Structure and dynamics of unique bluegill populations. Master s thesis. University of Missouri, Columbia. Neal, J.W., and D.W. Willis, editors Small impoundment management in North America. American Fisheries Society, Bethesda, Maryland. Willis, D.W., R.D. Lusk, and J.W. Slipke Farm ponds and small impoundments. Pages in W. A. Hubert and M. C. Quist, editors. Inland fisheries management in North America, 3 rd edition. American Fisheries Society, Bethesda, Maryland. Problem Set 3: Results and Discussion Questions (Due 26 Oct 2017) Please present a report of results by doing the following activities (50 pts). 1. Describe general nature and setting of the pond. 2. Describe the physical habitat of the pond. 3. Describe the water chemistry? Use the water testing measurements (YSI) as a guide. Present the water quality data in a table (mean ± SD). What do the water quality data that we collected indicate about the pond? Should any chemical manipulation be done to improve water chemistry? If so, what? Be specific and support your decision. Also consider any problems that might arise from these actions. 4. Describe the fish assemblage briefly, in general terms? 5. Now details: List the values of the indices you calculated above in the Analysis section. Be sure to include all species as appropriate (F:C ratio, Y:C ratio; AT for bass and bluegill; AT for the assemblage and individual species, PSD for bass and bluegill; PSD- Preferred and Memorable for bass and bluegill, average Wr for bass, bluegill, etc.). Interpret the meaning of each index. If you could make a professional looking table in a word processor containing all of these results that would be great! (25) 6. Does the conclusion of whether or not the pond is balanced depend on which index you used (F:C ratio, Y:C ratio, AT)? If so, why might they differ? (5) 7. Conclusion: Does this pond have potential to be a fishing pond? Is it in balance? If the pond is not balanced, explain what you could do to bring it back into balance. What are some of the limiting factors and how could you make it a recreational fishing pond quickly with little fiscal support? Support your answer with descriptions and evidence. Consider all the management activities you could do to achieve balance: stocking, harvest regulation, feeding, fertilizing, liming, supplementing or removing aquatic vegetation. Is there a problem with over abundance of aquatic vegetation in the pond leading to the imbalance? If so, do you have any suggestions about how to control it? Be specific. For example, if you decide to remove aquatic vegetation, explain why and how you would do it. (5) 3

4 8. Now that we are more familiar with this pond from sampling it (fish assemblage, water quality, and general observations), what would you need to do, if anything, to manage the pond to achieve PSD-63 for largemouth bass. What would be the advantages and disadvantages of managing the fishery in this way for this particular pond? (5) 9. Determine the length-weight relation for bluegill in this pond (i.e., make a Standard Weight Equation for bluegills in this pond that has the form Log10Ws = -a + b Log10 L a. To do this, graph weight (y-axis) as a function of length (x-axis) in a graphing program (e.g., EXCEL). Fit the data with a power function and place the equation and the r 2 -value on the graph. Convert the power function to a linear function using logarithms. Paste the graph into your problem set write-up. See the figure below for proper graph format. Interpret the meaning of this result figure. (10) b. Extra Credit for Undergraduates / Required for Grad students: Evaluate the consistency of our length-weight relationship to that of the relationship already established for bluegill (Hillman 1982; see text page 536). Hillman s equation was determined in Missouri, so it might not be applicable to bluegill in other regions. There are 2 ways you could do this evaluation. First, you could compare the parameters a (a constant) and b (exponent) of the two equations. Take the inverse log of both sides of Hillman s equation to get it in the form of W = al b so it is comparable to the equation on your graph from part a above. If this seems hard, try the second way: fit a straight line to your relationship. To do this, log transform your length and weight data (in excel use =log(cell reference) ). Then plot log weight (y-axis) vs. log length (x-axis). Fit the data with a linear fit function and place the equation and r 2 -value on the graph. The linear equation will be in the form of W=a+bL. But remember that we plotted the log values so be sure to recognize that the equation is really like logw = log a + b log L, where the value b is the slope of the line and the value log a is the y-intercept. Now we have the length-weight relationship in the form of an equation like Hillman s. Paste this graph into your write-up. Compare the intercepts and slopes (parameters a and b ) of the two equations (ours vs. Hillman s equation in the book). Explain how the two length-weight relationships are similar or different. Be specific by referring to how bluegill weight changes differently between our pond and the Missouri ponds as a function of bluegill length. Don t just tell me about different numerical values of the slopes and intercepts. Tell me what it means. (10) c. Extra Credit for Undergraduates / Required for Grad students: Find the Wr for each bluegill in the sample using the length-weight relationship equation we determined for the bluegill population of the pond (i.e., use the equation you got in part a above). Plot a frequency distribution of the relative weights (Wr). Compare the Wr s to that calculated using Hillman s equation in question number 2 above. Are there any important differences? If so, can you suggest some 4

5 reasons why? Plot both frequency distributions together on the same plot (different colors) to make the comparison more visual. (10) Figure 1. An example of the way a graph (which is really a figure in a report/manuscript) should be formatted. Copy it from Excel and Paste special in a WORD document as a Device Independent Bitmap or Enhanced Metafile. Note how the equation has been customized with the y- and x-variable names. 5