From our friends at the MN DNR.
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Greetings from DNR Fisheries;
Minnesota DNR Fisheries is conducting a tagging study of white bass on the Mississippi and St. Croix rivers this year. We thought spring had finally arrived and we were able to start tagging white bass this week. We got off to a great start before the snow hit and have already tagged about 850 fish in the Mississippi. Our window for tagging during the spawning aggregation will probably be short, so we will be out there tagging every day weather allows.
A big part of this study relies on reports of tagged fish from anglers, so we really appreciate your help and taking time to report tagged fish. If at all possible, please report tags through the DNR Website. It has a map tool that allows you to mark the location where you caught the fish and boxes to fill in with the information we need. A more detailed summary of the project is posted below, but if you have any questions, please contact Nick Schlesser [email protected] or Kevin Stauffer [email protected] by phone or email. Our phone number is (651) 345-3365. Nick’s extension is 235 and Kevin’s is 229. If you have questions about the St. Croix River, please contact Joel Stiras [email protected] or (651) 259-5806.
MN DNR White Bass Tagging Study
Mississippi and St. Croix Rivers – 2013
Project Background
White bass Morone chrysops have a limited distribution in the state of Minnesota, where this species is at the northern edge of their range and primarily found in larger river systems. As a sportfish, white bass are of minimal importance in most of Minnesota. However they are a significant component of the sport fishery in the Mississippi River from St. Anthony Falls downstream to the Iowa border, and in the St. Croix River from Taylor’s Falls to the mouth. Creel surveys have been completed on Mississippi River Pool 4/Lake Pepin in two of every six years since 1987. Although Pool 4 is widely renowned for its walleye and sauger fishery, white bass are frequently the most caught and most harvested fish as measured by creel surveys. In the St. Croix River, creel surveys in 1982 and 1997 showed anglers targeted walleye and sauger most often and very little effort was targeted white bass fishing. However, white bass were the most caught and most harvested fish in the 1982 St. Croix River creel survey. In the 1997 creel survey, white bass were only the fourth most caught species of fish, yet was still the number one species harvested.
Even though white bass are an important component of the sport fishery in the Mississippi River and St Croix River, there has been few detailed studies on this species. In general, white bass populations have been monitored through normal fisheries assessments without any targeted effort for this species. A long-term (1965-present) database of gill net assessments in Lake Pepin is probably the most reliable information available for white bass in Minnesota (MN DNR Large Lake Reports for Pool 4). This long data set indicates that white bass populations tend to be lower in abundance and less variable in the last 15 years than they were prior to that. Anecdotal comments from anglers in recent years also suggest that while the quality (size) of white bass in the river systems is still very high, the numbers of fish seem to be declining overall. High angler catch rates are still common, but the number of locations and periods of time this happens appear to be lower in recent years.
In recent years MN DNR has used otoliths to determine more accurate ages of white bass. They found substantial differences from estimated ages that were made from scale impressions. Meerbeek (2009) found white bass up to 16 years old, which nearly doubled the maximum age that had been determined from scale aging. Age and growth analysis from otoliths showed that white bass grow rapidly and reach 14 inches in length in their first 4-5 years of growth. After 14 inches, growth is slow but survival is much higher than was estimated from scale aging. The more accurate age determination raised questions about how this species should be managed and what other information should be collected.
This study will help fisheries managers gain a better understanding of white bass on the Mississippi and St. Croix rivers and determine whether or not a viable population estimate can be obtained with a mark-recapture study. It will also provide information on the movement from known spawning locations, as well as where and when angler harvest is occurring.
Methods
Beginning in April of 2013, MN DNR Fisheries staff will attempt to sample and tag up to 5,000 white bass in locations where they are known to concentrate during the spawning period. Tagging effort will roughly be apportioned with 3,000 tags in the Mississippi and 2,000 tags in the St. Croix. Since this type of tagging effort has never been attempted on either river, one of the primary components of the project is to determine whether or not an adequate number of fish could be tagged and recaptured for a viable population estimate.
White bass (> 8 inches) will be tagged near the dorsal fin with T-bar anchor tags. Tags will be individually numbered and identified with Minnesota Department of Natural Resources lettering. Approximately 25% of the tagged fish will be double tagged or fin clipped in order to estimate tag loss. Electrofishing will be the primary method of capture, however angling and other sampling gear may also be deployed.
Information signs and news releases will be used to inform anglers of the tagging project and instruct them on how to report capture of tagged fish. The primary reporting tool for angler caught fish will be through the MN DNR’s website, which has a map interface that allows the user to pan a map image and select the location where the fish was caught. To the degree possible, all anglers who report a tagged fish will be given information on the fish they caught and purposes of the study.
… no tags though.
