This project will improve aquatic habitat in Martin and Typo Lakes and interconnected wetland habitats by removing common carp with a science-based approach that incorporates existing carp barriers, radio tracking, and population analysis to set goals and track progress. Over three years we will do carp removals at Martin and Typo Lakes to remove carp to levels that are less harmful to water quality. To guide these and future harvests we will use radio tagging and tracking, age structure analysis of captured carp and identification of nursery areas. We will develop a long-term, location-specific, science-based strategy, and a decision-support tool (carp population model) to sustain project benefits after the grant period. By working throughout this chain of lakes we will create a connected network of habitat yielding multiple benefits to fish, wildlife and water.
Carp strongly degrade aquatic habitat and water quality through their feeding behaviors, and they currently are dominating fish biomass in these Lakes. By digging in the bottom while foraging, carp uproot plants, disturb sediments and release nutrient rich excrement into the water. The result is a lack of vegetative habitat, high turbidity and poor habitat for fish and waterfowl (Haas et al. 2007, Bajer et al. 2009). For this project, we will hire a U of M spin-off company, Carp Solutions LLC, who develop and apply carp management strategies using the most recent science. Carp control will improve water clarity, increase plants, improve game fish community, and enhance desirable wildlife populations.
This is the second phase of carp control at these lakes. In 2016 we completed installation of four strategic carp barriers, which were partially funded by a MN DNR Conservation Partners Legacy grant. The barriers separate spawning and overwintering areas to reduce carp reproduction. The barriers also prevent adult re-colonization after carp harvests, correcting a problem that had made benefits of previous harvests short-lived. While the “phase 1” carp barriers have benefits on their own, the “phase 2” harvests are the path to bigger, faster results.
Multiple aquatic habitats will benefit from this project. They include Martin and Typo Lakes, >1 mile of Typo Creek between the lakes, >150 acres of adjacent wetland and downstream waters of the Sunrise and St. Croix Rivers. This project is a priority in local and regional natural resource plans.
Carp harvested by box net will be donated to the Wildlife Science Center in Linwood, MN to feed their animals.
Box netting - Box netting of carp has occurred at Typo Lake in 2017-2018 and Martin Lake in 2018. At Typo Lake, in August-October 2017 we used two nets and later increased to three nets. In 2018 we have used four nets at both lakes. These nets are baited with cracked corn "train" carp to come to the traps. Traps are sprung before daylight, when carp are feeding most. Carp captures and progress toward the goal of reducing carp down to 100 kg/hectare are as follows:
Typo Lake - Estimated 18,808 carp in the lake. 5,652 carp removed as of October 2018. 30.1% of the carp have been removed and the goal is 74.0% of the carp removed.
Martin Lake - Estimated 13,409 carp in the lake. 3,366 carp removed as of October 2018. 25.1% of the carp have been removed and the goal is 75.5% of the carp removed.
Electrofishing - Electrofishing surveys are conducted to estimate carp populations. This will help us know how many carp need to be removed to reach management goals. Both lakes have been electrofished in August and September 2017. Martin Lake is complete. At Typo Lake shallow water prevented effective electrofishing, so the method was changed to also include inventory of box netted carp. During electrofishing many carp are fin clipped. Recaptures of fin clipped fish helps refine population estimates.
Radio tagging - 20 carp at each lake were implanted with radio transmitters (photos attached) and released. These “judas” fish will betray the habits and locations of entire schools for us in the future. Fish locations are tracked periodically. In the unlikely event that someone from the public catches one, we’d ask they return it to the water.
Trap netting juveniles - At both lakes trap netting for juvenile carp occurred in 2017. This helps us understand how often carp are reproducing, and is also a snapshot of the rest of the fishery. No young carp were captured in and around Martin and Typo Lakes, a good indication that these carp have not been reproducing recently. That is far better from a management standpoint than a population that is churning out new babies every year.
Aging analysis - Heads from >100 harvested carp at each lake were kept in 2017. These fish were aged by examining growth rings on an internal balance organ in their head. The resulting age structure of the population helps us understand how often carp are successfully reproducing. We found few young fish, indicating that carp are not reproducing in most years. Most carp were between 20 and 30 years old. This indicates that carp removal can have lasting positive effects on these lakes.
August 25, 2017 box netting at Typo Lake slide show
September 1, 2017 radio tag implantation at Typo lake slide show