Evaluation of Employing Trace Element Contents of Otoliths as a Natural Tag Using Lake Erie White Bass (Morone chrysops)
Project Number: R/LR-006-PD, Completion Report
Start Date: 12/1/2001
Completion Date: 8/31/2003
Revision Date: 10/30/2007
| Principal Investigator(s) | 1. | John R. Farver, Bowling Green State University* |
| Co-Principal Investigator(s) | 2. | Jeffrey G. Miner, Bowling Green State University* |
| This shows the current affiliation and may not match affiliation at time of participation. * | ||
Funding Record
| Source: Ohio Sea Grant College Program | |||
| Source Fund | State Match | Pass Through | |
| Total | $ 7,491.00 | $ 3,758.00 | $ 0.00 |
Objectives
The primary objective of this development project is to evaluate employing trace element contents of fish otoliths to address critical questions of stock discrimination and habitat use of Lake Erie fish. We will first investigate both the bulk elemental fingerprints and trace element zoning patterns of otoliths in adult white bass (Morone chrysops) from the Maumee and Sandusky Rivers, two important Ohio river systems in the Lake Erie watershed, as well as from reef-spawning sites. The primary reasons for using the white bass in this exploratory study are: 1) they spawn in rivers and the reef system of western Lake Erie, so they provide an important analog to walleye; 2) they are spawning currently and we are in a position to collect them; and 3) we have preliminary data suggesting clear partitioning of stocks from the two river systems (based on parasite loading data from 1998). Our long-term goals include establishing and comparing the geochemical signatures of walleye and white bass using the different spawning sites through time to determine if common site-specific signatures are available. However, we must first determine the technique that will provide the most definitive signatures, and white bass provide a timely and appropriate tool for this study.
Rationale
Walleye, the most important sport and commercial fish in Lake Erie, and white bass use the Maumee and Sandusky rivers, as well as the reefs in western Lake Erie, as primary spawning sites. However, the relative contribution of each stock to the overall population is not well known. In addition, we do not know the extent to which these stocks mix (use common habitat) throughout the year. Genetic markers have shown promise for stock identification in some fisheries applications. However, the accuracy of identifying fish to specific stocks is limited when there is significant genetic exchange or when there is insufficient genetic variation. One of the primary questions for fishery managers in Lake Erie is the relative contribution of different stocks to a population and not the extent of genetic isolation. Thus, techniques that can identify unique signatures of spawning stocks would be useful to resource managers. For example, if the Maumee River stock is found to be a major contributor to the lake-wide population, then specific management practices to support the river-spawning stock could be implemented. Here we propose to compare the elemental signatures of walleye and white bass using these different spawning sites through time to determine if common site-specific signatures are available.
In addition to identifying spawning stocks, the techniques we will employ provide a means to discern changes in habitat use if accompanied by water chemistry changes. For example, white bass collected in 1998 from the Maumee River had substantially higher parasite loading rates than fish spawning in the Sandusky River. These results suggest that the white bass may be spending long periods of time in degraded habitats surrounding Maumee Bay. We will employ line-scans of trace element contents across longitudinal sections of otoliths (exposing matrix material accrued during ontogeny and particularly across seasons) to determine changes in chemical signatures through time. These analyses will provide qualitative data on the proportional use of habitats (e.g., Maumee Bay versus the northern or eastern regions of western Lake Erie) by individual fish stocks, a critical parameter in any meaningful fish management program.
Methodology
Trace element abundances in the otoliths will be determined using inductively coupled plasma mass spectrometry (ICPMS) either by laser ablation (LA-ICPMS) for spot analyses, or, isotope dilution (ID-ICPMS) for bulk analysis. In addition, fine-scale elemental zoning will be analyzed using an ion microprobe (SIMS). The approach is based upon the observation that elemental and isotopic abundances in fish otoliths are directly and predictably related to the chemistry of the water in which they grew. Recent advances in the analytical tools to be employed will yield high precision data that can be spatially correlated with the annular structure in the otoliths, thus providing a chronologically correlated record of changes in water chemistry (ie, habitat) throughout the fish's lifetime. Part of this project will involve comparing the utility of these techniques (i.e., ion probe provides better spatial resolution than LA-ICPMS, which has typically been used, and analysis of the nucleus of juvenile and adult fish to recover natal site signatures requires high spatial resolution),and establishing appropriate protocols.
Benefits & Accomplishments
- The application of analytic methods, like LA-ICPMS, that combine high spatial resolution with low detection limits for a broad range of elements, show great promise in addressing fundamental questions of fish stock differentiation and changes in habitat use.
- Our analysis of otoliths from adult white bass spawning in the Sandusky and Maumee Rivers showed:
- Consistent with the differences in river water chemistry, the otolith cores of fish from the Sandusky River typically show significantly greater Sr contents compared to fish from the Maumee River.
- There are clear changes in Sr content across individual otoliths (core to rim) indicating changes in water chemistry.
- Similar Sr contents are obtained for otolith cores from most, but not all, fish spawning in the same river.
Publications & Media
| Presentations | |
 | Getz, R., Farver, J.R. and Miner, J.G. 2003, Lake Erie white bass: can otolith chemical signatures differentiate stocks 43rd Ohio Fish and Wildlife conference, February 7. |
Supported Students
 | Getz, Robert (Graduate, M.S.) Bowling Green State University Title: Using Microchemistry of Otoliths from Adult Morone chrysops from the Maumee and Sandusky Rivers (Ohio) as a Chemical Fingerprint to Determine Habitat |
