Juvenile Lake Sturgeon Gill Netting a Success!!
BY KEVIN MANN, GREEN BAY FWCO
Credit: Rob Elliott, USFWS
On the afternoon of September 18th, 2013 a crew from the U.S. Fish and Wildlife Service's Green Bay Fish and Wildlife Conservation Office traveled to Little Bay De Noc in Michigan’s Upper Peninsula in search of a small, elusive fish. The purpose of this trip was to conduct an exploratory assessment of juvenile lake sturgeon off the mouth of the Whitefish River, Michigan, one of 6 rivers around Lake Michigan where young sturgeon are being rearing in streamside rearing facilities and released into the wild to restore and rehabilitate populations. This survey was a pilot effort for the development of a juvenile lake sturgeon index survey that can track the abundance and demographics of this species over time in Lake Michigan using standardized gear.
Streamside rearing involves collecting eggs and/or larvae from the wild and raising them in a facility which pumps in water directly from the target river. Fish are raised in constant contact with their natal water source so they can imprint to that river. Once they’re released, the imprinting should allow the young fish to return to the target river after they are mature enough to spawn. These facilities are part of multi-agency and stakeholder partnership to either supplement or reintroduce lake sturgeon populations within these six rivers. As part of a joint effort with the Michigan and Wisconsin Departments of Natural Resources and the Little River Band of Ottawa Indians, the Service is helping with these pilot gill net surveys in Lake Michigan near these six river mouths to locate juvenile lake sturgeon released from the facilities.
indicating the fish was released from the
Whitefish River streamside rearing facility.
Credit: Kevin Mann, USFWS
During the Little Bay De Noc survey which used graded mesh monofilament gill nets, two juvenile lake sturgeon were captured in a single 1000 foot net. Both fish were measured for length, weight and girth and checked for a telltale signs of their streamside origin. Each fish was missing its left pelvic fin, and contained both a PIT (passive integrated transponder) and CWT (coded wire tag) that let biologists know both these fish were released from the Whitefish River facility in 2010.
the mouth of the Whitefish River, MI.
Credit: Kevin Mann, USFWS
Additional gill netting has been occurring near the remaining five rivers. Earlier this summer, netting outside the Milwaukee River resulted in capturing multiple streamside reared lake sturgeon and netting outside the Kalamazoo River in recent years has recaptured fish released from that streamside facility in 2010 and also fish released into the Milwaukee River. Netting off the Cedar River and in Big Bay de Noc in recent years has also captured fish originating from area streamside rearing facilities. Finding streamside reared lake sturgeon is an important part of the monitoring process. It indicates that fish raised in these facilities are surviving and growing well after their release. With continued success, it is hoped that in 10-15 years, sturgeon from these rearing facilities will be returning to spawn in the rivers in which they were released.