Tribes and state agencies work together to restore sturgeon population in Great Lakes watersheds
A variety of approaches including unique streamside rearing facilities in Michigan and Wisconsin are reintroducing young lake sturgeon into select rivers to develop a sustainable population of this once abundant species.
Historically, the lake sturgeon has been an important member of the Great Lakes fish community. One of the oldest species of fish in existence, a special 2012 report by the Michigan Department of Natural Resources (MDNR) notes there are approximately 29 different species of sturgeon worldwide but only the lake sturgeon (Acipenser fulvescens) is native to Michigan. Sturgeon are toothless bottom-feeders, swallowing crayfish, nymphs, and other small aquatics creatures they find by stirring up sediment on the beds of rivers and lakes with their long, rubbery, spade-like snout. Streamlined in shape with bony plates along their sides and backs, their skeleton is primarily cartilaginous. Sturgeon grow larger and live longer than any other North American freshwater fish. Lake sturgeon can grow to over eight feet in length and weigh up to 800 pounds. Males may live 55 years and females have been known to reach 150 years. Like other long-lived species, they mature slowly and reproduce infrequently. According to the MDNR, sexual maturity males do not reach sexual maturity until 12-17 years of age, spawning every 1 to 4 years thereafter. Females have been known to reach maturity anywhere from 14-33 years of age, though most often at 24-26 years of age. Females only spawn every 3 to 7 years. Other than humans, they have few natural predators.
Prior to European settlement, several Great Lakes tribes built a life around sturgeon which was found in abundance in several large river and lake systems, their primary habitat. Not only did the tribes use the meat, skin, and oil; the sturgeon took on spiritual meaning as well for them. In the late 1800s, however, the sturgeon population in the Great Lakes suffered a dramatic reduction in numbers. This decline is attributed to a combination of overfishing, pollution and habitat loss. Their naturally slow rate of maturation and low rate of reproduction further exacerbated the lake sturgeon’s situation.
During the late 1800s and early 1900s, the number of European settlers in the Great Lakes region continued to grow. There was a related increase in agricultural and logging activity and dams were constructed to meet a growing need for electricity and to provide water for drinking and crop irrigation. As mature sturgeon return each spring to spawn in the very same streams and rivers in which they were born, these dams not only destroyed sturgeon habitat, they often blocked critical migration routes to these spawning areas. Logging and certain agricultural practice caused soil erosion along the shores of rivers and streams, depositing sediment in former spawning areas which further impacting the sturgeon’s viability.
Early commercial fishermen initially considered sturgeon a nuisance fish. Their bony plates damaged fishing nets so often those caught were killed and dumped on the river banks to rot. Later, sturgeon meat and eggs became so prized that Great Lake commercial fisherman then targeted them, harvesting an average of 4 million pounds annually between 1879 and 1900.
As a result of this increased fishing pressure and the environmental challenges to their habitat and spawning grounds, the sturgeon population suffered a serious decline. During the 20th century, sturgeon catches dropped so drastically that several Great Lakes states began instituting more stringent regulations and limiting sturgeon fishing seasons.
In 2002, a unique collaboration, Lake Sturgeon Streamside Rearing-Lake Michigan Partnership, was formed with funding from the Great Lakes Fishery Trust, the Great Lakes Fish & Wildlife Restoration Act, state agencies, tribes, and universities. Biologists and researchers from these entities first conducted an assessment of lake sturgeon in Lake Michigan. They found at least eight rivers around Lake Michigan where sturgeon populations still existed though in fewer numbers than they had historically. Young sturgeon have a poor rate of survival and, as noted above, they take many years until mature enough to reproduce. This study identified what needed to be done to successfully rebuild their numbers. Researchers discovered distinct genetic differences existed in wild sturgeon depending on their river of origin. Because of this factor, guidelines were developed to insure that the genetic characteristics of each distinct population was carefully maintained during the rebuilding process.
A rearing technique to preserve these important genetic differences was developed. Known as streamside rearing, young sturgeon are raised in water pumped into the facility from the target river. The purpose of this approach is to allow the young fish to imprint to the river water as their counterparts in the wild do. This imprinting increases the likelihood that mature adults return from Lake Michigan to their river of origin to spawn and reproduce. Biologists will monitor the various sturgeon populations for 25 years to determine if they have increased in numbers as well as maintained their genetic diversity. In their 2012 report, MDNR researchers identified 24 distinct lake sturgeon populations existing in various Michigan watersheds, but categorized only five of these populations as large in size with most of the remaining populations at risk of extirpation (local extinction).
The Little River Band of Ottawa Indians (LRBOI) began the first streamside rearing operation on the Manistee River in 2004. Their model was then used in 2006 to develop similar facilities on additional rivers in both Michigan and Wisconsin. As recent as 2011, a new facility was established on the Kalamazoo River. Both MDNR and Little River Band of Ottawa Indians (LRBOI) have been active in this ongoing collaboration to rebuild a healthy lake sturgeon population in Michigan.
Each fall, LRBOI conduct a ceremony marking the release of fingerling sturgeon into the Manistee River. In the 10 years of operating this first-of-its kind streamside rearing facility, the tribe has released over 300 young sturgeon. More information, including an agenda and map to the site, regarding their 2013 release ceremony scheduled for Saturday, September 14, can be found on the event flyer.
Michigan State University Extension has several Sea Grant educators who work to maintain a healthy coastal ecosystem and sustainable fisheries in the Great Lakes region. Michigan Sea Grant is a cooperative program between Michigan State University and the University of Michigan to “promote better understanding, conservation and use of Michigan’s coastal resources”.