ESS 445 Fisheries Science and Management: Biology, Ecology, Management, and Conservation of North American Freshwater Fisheries and Aquatic Ecosystems Lab Problem Set 6 (20 Points) 30 Nov 2017 Fishing aging and growth lab Introduction An important part of conservation is determining the age of individual animals. One of the most common uses of age data is evaluating the age composition of populations and looking for age strata that may identify individual year classes (cohorts). The strength of individual cohorts can then be used to evaluate what external factors (such as temperature, precipitation, contaminants, etc.) may have influenced its strength. The presumed age of individuals is often used by biologists and managers to further evaluate the size of individuals in a cohort. For fish, these data are normally presented in age-length (actually length as a function of age) regression curves that will generally have a positive-log shape and will generally (given a large enough sample size) become asymptotic at y-length. Fishery managers are not the only biologists with an interest in knowing the age of the individuals of a target population. For example, age is strongly and positively correlated with a suite of fish health metrics. When evaluating for the presence/absence of fish health biological markers, it is generally suggested to sample individuals older than 3 years of age. Ecosystem ecologists use the age of individual fish to evaluate the system as a whole. For example, if the adult spawning population of a certain species is on average 3 years younger when compared to the species from another basin, we would like to know the causative drivers of this observed difference. Objective The primary objective of this lab is to introduce you to the variety of ageing structures and techniques available to fishery professionals and to give you the opportunity to age individual fish. We will also use our aging information to estimate growth rate of fish. Materials and Methods As discussed in lecture, there are several structures used to age fish and, equally, several ways to prepare them for reading. In the past, we collected numerous fish as a part of fisheries assessment projects. These fishes are preserved in 70% ethanol. We will age fish using their scales and we will show how otoliths on the larger fish are extracted. We have range of otolith pictures, as well as other hard parts, that show what the final end product looks like for aging purposes. You will have the chance to extract otoliths on your own. 1
Problem Set 6 Directions (Due on Dec 7, 2017, 20 points) 1. Split into groups. For scale aging, groups of 2 will be fine. For hard part extraction, make larger groups of say 4-5. 2. Extraction hard structures. Summarize what you were able to extract and see on the fish. Where you successful at extracting intact, unbroken otoliths? (OMIT). 3. Aging scales. Gently pull scales off of a fish and record the species and total length. We did this in the field. To examine scales, try to press them between 2 microscope slides or use the scale press to make an impression of the scale in an acetate slide. Compare your age estimates to your partner s estimate and come to a final agreement on what the age is. Record ages on the following table (5 points). Try to age as many parts as possible there should be more than enough scales to go around. Share your scales with another group. Your Fish ID Structure used Reader 1 Age Estimate Reader 2 Age Estimate Comments and Final Age Agreement 2
4. Back-calculate the length at age of at least one LMB or SPB or some other large fish from which you took a scale. If possible, it should be at least 3 years old, preferably older. You will have to use a dissecting scope with an ocular micrometer to do this. Fill out table below completely and correctly to back calculate length at age and then calculate the fish s growth rate. What is the fish s growth rate in mm/day averaged over the life of the fish? Also, report growth in inches per day, or another unit of rate meaningful to YOU. (10 Points) Li = (Si * Lc ) / Sc Li = back-calculated length of fish when ith increment formed. Lc = total length of fish at capture. Sc = radius of hard part at capture. Si = radius of hard part at the ith increment Fish Species TL (mm) or Lc Age Growth Rate mm/day 1 2 Fish 1 Sc = Lc = S1 = L1 = S2 = L2 = S3 = L3 = S4 = L4 = S5 = L5 = S6 = L6 = Fish 2 Sc = Lc = S1 = L1 = S2 = L2 = S3 = L3 = S4 = L4 = S5 = L5 = S6 = L6 = 3
5. Aging other hard parts. Practice your skills aging fish hard parts on the Webpage for Age and Growth of Fishes: http://jcsites.juniata.edu/faculty/merovich/fishage_growth. Final age agreement is provided on the last page of each document, so you can check to see how well you do. Do at least 10 structures across at least 3 different samples listed on the webpage. Number Species Structure and Number 1 2 3 4 5 6 7 8 9 10 11 Your Estimate Final Agreement Comment (did your age estimate match?) 6. Growth rates. You are a fisheries biologist in charge of managing Cheat Lake in northcentral, WV. Use the data that were collected by your technicians to compare the growth rate of largemouth bass and spotted bass. Graph mean length at age for ages 1-4. Also include estimates of largemouth bass growth rate from at least one other location and explain if you think the largemouth bass have a sufficient growth rate in Cheat Lake. Include the citation of the external data source (web pages are OK i.e., you should find some DNR webpages with some data for the eastern US and the PA F&BC has data listed as well). (5 points) 4
DATA FROM CHEAT LAKE 11-12 September 2008 Fish Techniques Class Age Species TL (mm) Wt (g) 1 LMB 145 30.7 1 LMB 225 132.0 1 LMB 210 97.0 2 LMB 225 120.8 2 LMB 233 139.2 2 LMB 222 125.7 3 LMB 220 140.2 3 LMB 320 348.2 3 LMB 288 303.1 3 LMB 295 252.0 3 LMB 485 684.1 3 LMB 210 110.3 3 LMB 316 387.6 3 LMB 304 320.5 4 LMB 450 1087.0 4 LMB 310 379.8 4 LMB 385 685.7 4 LMB 330 443.7 4 LMB 424 860.9 5 LMB 341 399.5 6 LMB 510 1879.6 Age Species TL (mm) Wt (g) 1 SPB 152 37.9 1 SPB 123 19.7 2 SPB 190 81.3 2 SPB 199 95.1 2 SPB 255 183.5 2 SPB 220 111.0 2 SPB 210 91.7 2 SPB 235 152.7 3 SPB 210 108.8 3 SPB 279 231.2 3 SPB 280 281.5 3 SPB 330 425.2 3 SPB 220 128.0 3 SPB 276 226.9 3 SPB 231 147.9 3 SPB 221 114.7 4 SPB 271 276.0 4 SPB 278 233.0 4 SPB 283 305.5 4 SPB 326 436.8 4 SPB 280 275.3 4 SPB 235 137.0 4 SPB 335 138.6 4 SPB 274 229.2 4 SPB 270 245.3 4 SPB 258 204.9 4 SPB 246 274.5 4 SPB 229 140.5 5 SPB 342 498.0 5 SPB 312 366.0 5
Suggested Further Reading: Baker, E. A., & T. S. McComish. 1998. Precision of ages determined from scales and opercles for yellow perch Perca flavescens. Journal of Great Lakes Research 24:658 665. Campana, S. E. and D. Neilson. 1985. Microstructure of Fish Otoliths. Canadian Journal of Fisheries and Aquatic Sciences 42:1014-1032. Casselman, J. M. 1973. Analysis of hard tissue of pike Esox lucius L. with special reference to age and growth. Pages 13 27 of: Bagenal, T. B. (ed), Proceedings of an International Symposium on the Ageing of Fish. European Inland Fisheries Commission of FAO, The Fisheries Society of the British Isles, and The Fish Biological Association (Unwin Brothers). DeVries, D. R., and R. V. Frie. 1996. Determination of age and growth. Pages 483 512 (Ch 16) of: Murphy, B. R., & Willis, D. W. (eds), Fisheries Techniques, second edition. American Fisheries Society, Bethesda, Maryland. Hoff, G. R., D. J. Logan, and D. F. Markle. 1997. Otolith morphology and increment validation in young Lost River and shortnose suckers. Transactions of the American Fisheries Society 126:488 494. Koch, J. D., and M. C. Quist. 2007. A technique for preparing fin rays and spines for age and growth analysis. North American Fournal of Fisheries Management 27:782-784. Koch, J. D., W. J. Schreck, and M. C. Quist. 2008. Standardised removal and sectioning locations for shovelnose sturgeon fin rays. Fisheries Management and Ecology 15:139-145. LeCren, E. D. 1947. The determination of the age and growth of the perch (Perca fluviatilis) from the opercles. Journal of Animal Ecology 16:188 204. McCarthy, M. S., and W. L. Minckley. 1987. Age estimation for razorback sucker (Pisces: Catostomidae) from Lake Mohave, Arizona and Nevada. Journal of the Arizona-Nevada Academy of Science 21:87 97. Quist, M. C., M. A. Pegg, and D. R. DeVries. 2010. Age and growth. Pages 677-731 (Ch 15) of: Zale, A. V., Parrish, D. L., & Sutton, T. M. (eds), Fisheries Techniques, third edition. American Fisheries Society, Bethesda, Maryland. Scoppettone, G. G. 1988. Growth and longevity of cui-ui and longevity of other catostomids and cyprinids in western North America. Transactions of the American Fisheries Society 117:301 307. Scoppettone, G. G., and G. Vinyard. 1991. Life history and management of four endangered lacustrine suckers. Pages 359 377 of: Minckley, W. L., & Deacon, J. E. (eds), Battle against extinction: native fish management in the American West. University of Arizona Press, Tucson. Secor, D. H., J. M. Dean, and E. H. Laban, 1991. Manual for otolith removal and preparation for microstructural examination. University of South Carolina, Baruch Institute for Marine Biology and Coastal Research (Technical Report 91-1), Columbia, SC. 6