Larval Trapping and Fyke Netting

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Larval trapping is conducted in the spring and is used to detect the presence or absence of egressing larval northern pike and/or other species originating in Program tributaries. The WDNR has used larval traps to successfully detect larval northern pike in Lake Michigan tributaries near Green Bay, WI. As such, the method was adopted and added to the ecological monitoring program subsequent to work plan development and finalization.

Two types of traps are used in our surveys, box traps and quatrifoils.  Quatrifoil traps require a glow stick and are utilized in areas that have little to no stream flow.
  
Like visual surveys, larval trap netting filled a critical gap in the Program’s ecological monitoring and provided a reliable, consistent method for detecting northern pike spawning in Program tributaries.

Fyke nets were deployed in Program tributaries between April 8 and April 23, 2010 (i.e., shortly after spring thaw, immediately upon equipment receipt, and prior to impediment removals) to document the presence or absence of adult northern pike and other migratory fish species during the typical northern pike spawning season.

Larval Trap Set-Up

Larval Trap Set-up

Fyke Net

Fyke Net
Larval Trapping Educational Poster:
  1. Larval Trapping Poster
Notable 2015 Findings
Naturally Reproducing Coho Salmon and Rainbow Trout in Ozaukee County! 

Coho Salmon were found in larval traps in both Mineral Springs Creek as well as Mee-Kwon Creek. Also in Mee-Kwon Creek, a Rainbow Trout was found. Salmon populations in the Great Lakes are supported largely by stocking and naturally reproduced salmon are considered rare in Ozaukee County streams.

Documenting the success of salmonid natural reproduction helps the biologists manage the Great Lakes fisheries more effectively. 
Ulao Creek is a Northern Pike Hotspot! 

 Our larval trap in Ulao Creek caught multiple Northern Pike born in spring of 2015. This indicates that adult Northern Pike are using Ulao creek to reach spawning habitat. 

A healthy and obstruction free Ulao Creek is important to the life cycle and spawning success of Northern Pike.

The Ozaukee County Planning and Parks Department Fish Passage Program is currently working on Ulao Creek to restore natural stream functions and to connect and enhance high quality habitat for native fish, birds and wildlife. 

  1. Ulao Creek Restoration Sign







Northern Pike

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Other Notable Catches of 2015

Northern Pike and Salmonids weren't the only interesting things caught in 2015. Other fish and frog species of interest turned up in our traps.

Many tadpoles and frogs were caught in 2015. In the picture to the left you can see a bullfrog tadpole next to a green frog tadpole. The easiest way to distinguish them is by looking at the spots on their backs. Bullfrog tadpoles have spots with distinct margins while green frog tadpoles have spots with "blurry" margins.

While green frogs and bullfrogs were the most common, a wide variety of frogs were observed such as the leopard frog (see picture on left).

Other fish species to note are the colorful Iowa darter and the northern redbelly dace.

Yellow Perch

Yellow Perch

2015 Larval Trapping Summary

2015 Larval Trapping Summary