Influence of parental phenotypes in characteristics of early life history stages of walleye.
Jason J. Van Tassell, Ph.D. student, Jacques Rinchard, Postdoctoral Fellow, Roy A. Stein, Konrad Dabrowski, and Elizabeth A. Marschall. Funded by: Ohio Department of Natural Resources, Division of Wildlife, Federal Aid in Sport Fish Restoration.

The walleye (Sander vitreus) fishery comprises the largest in Lake Erie and is a primary target of recreational anglers and commercial fishers (ODW 2003). Important economically, the walleye fishery contributes to local shoreline communities as anglers from around the Great Lakes region and the world visit ''the walleye capital of the world''. Further, an important commercial, gillnet fishery for walleye exists in Canadian waters (Provincial waters of Ontario). Most recently, this important game fish has declined in population size to ~17 million age 2+ walleye from 69 million at its peak in 1988 (Christopher Vandergoot, Ohio Department of Natural Resources (ODNR), Sandusky, Ohio). Owing to its high recruitment variability (ranging 1.6 - 48.7 million for 1978 to 2002, Christopher Vandergoot, ODNR, Sandusky, Ohio) and its economic/ecological value, management agencies are motivated strongly to better understand walleye recruitment dynamics.

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Recruitment vs Annual Growth Project

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Jason can be emailed at van-tassell.1 "at" osu.edu

At the Maumee River, anglers crowd in shoulder to shoulder to fish The Walleye Capital of the World: Lake Erie.

Conventional wisdom suggests that most reproduction occurs in the Western Basin of Lake Erie. The Maumee River and Western Basin reefs (including both Ohio and Ontario waters) are thought to be the primary spawning sites, with smaller runs occurring in the Sandusky River and smaller rivers (e.g., Grand River, Ohio; Roger Knight personal communication, ODNR, Sandusky, Ohio). Based on mitrochondrial DNA, Maumee River and the Sandusky River walleye have been suggested to differ from one another, but insufficiently to be considered independent populations or stocks (Merker and Woodruff 1996). Walleye from the Grand River are genetically indistinguishable from those from the Maumee River (Merker and Woodruff 1996) but are distinguishable from walleye spawning in the Sandusky River (Stepien and Faber 1998). The idea of separate spawning stocks is further supported by tagging data that suggest walleye return to their natal grounds to spawn (Todd and Haas 1993, M. Turner personal communication, ODNR, Sandusky, Ohio).

Given the observed genetic structure related to spawning location, and that coupled phenotypic and genetic divergence can evolve rapidly (Gislason et al. 1999, Hendry et al. 2000), stocks also may differ with regard to adult phenotypes, such as size, fecundity, egg size, and egg viability (females) or fertilization ability (males). If these attributes are associated with offspring number and success, different stocks may be contributing disproportionately to lakewide walleye recruitment. To further reinforce this potential, these groups may spend their adult lives spatially separated from one another within the lake, which translates to differences in forage base, habitat use, and migration costs, which in turn could lead to differences in adult phenotypes. Our working hypothesis is that distinct walleye stocks do exist and, if phenotypic differences exist among them, these stocks may well contribute differently to recruitment.

Ben Sylak and ODW personnel shock walleye
in the Sandusky River.

In the western basin of Lake Erie, Ben Carr and Jason Van Tassell pull a gillnet with walleye.

References

Gislason, D, M. M. Ferguson, S. Skulason, and S. S. Snorrason. 1999. Rapid and coupled phenotypic and genetic divergence in Icelandic Arctic char (Salvelinus alpinus). Canadian Journal of Fisheries and Aquatic Sciences 56:2229-2234.

Hendry, A. P., J. K. Wenburg, P. Bentzen, E. C. Volk, and T. P. Quinn. 2000. Rapid evolution of reproductive isolation in the wild: Evidence from introduced salmon. Science 290:516-518.

Madenjian, C. P., J. T. Tyson, R. L. Knight, M. W. Kershner, and M. J. Hansen. 1996. First-year growth, recruitment, and maturity of walleyes in western Lake Erie. Transactions of the American Fisheries Society 125:821-830.

Merker, R. J. and R. C. Woodruff. 1996. Molecular evidence for divergent breeding groups of walleye (Stizostedion vitreum) in tributaries to western Lake Erie. Journal of Great Lakes Research 22:280-288.

Mion J. B., R. A. Stein, and E. A. Marschall. 1998. River discharge drives survival of larval walleye. Ecological Applications 8:88-103.

Ohio Division of Wildlife (ODW). 2004. Ohio’s Lake Erie Fisheries 2003. Annual status report. Federal Aid in Fish Restoration Project F-69-P. Ohio Department of Natural Resources, Division of Wildlife, Lake Erie Fisheries Units, Fairport and Sandusky. 96 pp.

Roseman, E. F, W. W. Taylor, D. B. Hayes, R. L. Knight, and K. O. Paxton. 1996. Walleye egg deposition and survival on reefs in Western Lake Erie (USA). Annales Zoologici Fennici 33:341-251.

Roseman, E. F, W. W. Taylor, D. B. Hayes, R. L. Knight, and R. C. Haas. 2001. Removal of walleye eggs from reefs in western Lake Erie by a catastrophic storm. Transactions of the American Fisheries Society 130:341-346.

Stepien, C. A. and J. E. Faber. 1998. Population genetic structure, phylogeography and spawning philopatry in walleye (Stizastedion vitreum) from mitochondrial DNA control region sequences. Molecular Ecology 7:1757-1769.

Todd, T. N., and R. C. Haas. 1993. Genetic and tagging evidence for movement of walleyes between Lake Erie and Lake St. Clair. Journal of Great Lakes Research 19:445-452.

We propose to test whether adult phenotypes differ among spawning stocks (objective 1), whether adult phenotype translates to offspring phenotype and, therefore, potential survival of offspring (objective 2 and 3), and whether parental effects help explain recruitment variation (objective 4). Our objectives are:

1. Describe the phenotypic traits of spawners (length, weight, age, relative condition, reproductive timing) for three Lake Erie walleye spawning stocks, i.e., Maumee and Sandusky rivers and open-water reefs. Phenotypes will be compared both across spawning sites and within spawning sites across the spawning season.

2. Relate maternal phenotypes (e.g., size, age, fat reserves) to early-life stage phenotypes, likely to influence survival, such as egg size, lipid level, and fertilization success, for these three Lake Erie walleye spawning stocks. Similarly, these same female phenotypic traits will be related to larval traits likely to be important for survival, such as size at hatch and oil globular volume.

3. Describe how paternal phenotypes (e.g., size, age, fat reserves, sperm density) are related to early-life characteristics, such as fertilization success and larval size at hatch, for the three walleye populations.

4. Combine our data with abiotic and biotic data, historically important to walleye (Madenjian et al. 1996, Roseman et al. 1996, Mion et al. 1998, Roseman et al. 2001), and data from two concurrent AEL research projects (Jennell Bigrigg and Samantha Fedor), into a dynamic programming model to explore how various management strategies might influence walleye populations.

We seek to determine if parental phenotype of a large, iteroparous fish explains early life history success. Understanding how size-dependent factors influence recruitment is critical to the management of an exploited population. Our results will span three dimensions of interest to fishery managers: spawner size, time during the spawning season, and spawning sites. Understanding parental effects will allow us to determine whether a specific spawner size requires greater protection due to its differential contribution to recruitment. By measuring adult phenotypes through the spawning season, we will determine if specific times during the run (e.g., when highest quality adults are present) warrant special protection. Finally, comparing results from specific spawning locations will allow managers to assess whether protecting specific spawning stocks is warranted.