Green Bay FWCO - Great Lakes Fish Tag and Recovery Laboratory
Fifth Season of Mass Marking Field Collections
BY KEVIN PANKOW, GREEN BAY FWCO
Service technicians Tyler Lueck (right) and Caitlin McNamara (left) collect data on a sport caught salmon at Port Washington, Wisconsin. Credit: Kevin Pankow, USFWS
Through this program, the Lab operates four automated tagging trailers at state and federal hatcheries to ensure all Chinook salmon and lake trout stocked into Lakes Michigan and Huron receive adipose fin clips and CWTs injected into the snout. Each CWT is a 1.1 mm long piece of stainless steel wire with a laser-etched numerical code specific to a group of fish with the same stocking location, genetic strain, year class, and hatchery of origin. The clipped adipose fin identifies hatchery-reared fish and indicates the presence of a CWT.
Service Technician Barrett Warmbein prepares to record data on a sport caught lake trout at South Haven, Michigan. Credit: Kevin Pankow, USFWS
The 2016 field season began in Michigan City, Indiana on April 15th. Over the course of eight weeks, six teams were trained on several field collection protocols. The technicians received hands-on training in identifying salmon and trout species; collecting basic biological data such as fish length, weight, sex and maturity; collecting aging structures including otoliths (ear bones), scales, and maxillae (jaw straps); determining the presence or absence of CWTs and various fin clips; and identifying different types of sea lamprey wounds. Snouts containing CWTs will be collected, extracted and read throughout the summer and fall. The information contained in the CWTs are then coupled with the biological data collected by the technicians and stored in a database for analysis.
The Lab is also using its lake-wide sampling network to collaborate additional studies. Tissues, consisting of a dorsal muscle tissue, belly tissue, and stomachs, will be collected from Lake Michigan salmonines (Chinook salmon, lake trout, rainbow trout/steelhead, brown trout and coho salmon) to help understand how predators are adapting to a changing forage base. This study will be done in collaboration with the University of Wisconsin-Milwaukee, Illinois Natural History Survey and Purdue University. In addition, otoliths from rainbow trout/steelhead will be collected for a study to estimate the proportion of wild Lake Michigan rainbow trout that originate from different tributaries. Otolith microchemistry, which detects chemical “fingerprints” present in the otolith and the environment, will be used to determine the natal stream or region from which the wild fish were hatched. By performing this analysis throughout various times of the year, we will gain insight into where those fish move throughout the summer and fall. This study will be done in collaboration with Central Michigan University and Michigan Department of Natural Resources.