Michigan fisheries biologist Mike Thomas has found a great use for the pesky round goby - sturgeon bait.
Thomas and a research crew are amid a three-week effort to catch as many Great Lakes sturgeon as possible in the North Channel of the St. Clair River, where it flows into Lake St. Clair's Anchor Bay off Mount Clemens, Mich.
They are using long set-lines, which resemble overgrown catfishing trotlines, anchored off buoys to the bottom, down where these ancient fish live.
"We started this project to get a handle on what the sturgeon population was like here," Thomas said during a run Tuesday aboard the Channel Cat, a 46-foot steel converted trapnet boat used by the Michigan Department of Natural Resources. The vessel generally operates out of the agency's Lake St. Clair Fisheries Research Station at Anchor Bay.
"We bait with round gobies," Thomas noted. Gobies have become a widespread pest in the Great Lakes, having been introduced here from overseas in the dumped ballast-water of a freighter. They prey on fish eggs, such as those in unguarded smallmouth bass nests. At least sturgeon, and most gamefish, like to eat them.
The goby bait works. Sturgeon don't even mind if they're half rotten. Last Tuesday the MDNR crew hauled in eight fish in its daily check of eight sets. The catch ran from 28 to 61 inches and weighed from about 5 to about 61 pounds. On their best day this spring the crew has taken 22 sturgeon.
The fish are weighed and measured, a pectoral fin sample is removed for an aging study, and blood is drawn for DNA analysis and other tests. Afterward, each fish is "burped" like a baby to relieve internal air-pressure built up from being brought up from the deep, before being released. The ancient sturgeon does not have the more sophisticated air bladder of more modern fish species, and has a vented opening through which air can be burped back up the throat.
"They spawn very intensely for a very short time," Thomas said. The key is water temperature of 13 degrees Centigrade (about 55 degrees Fahrenheit). So for about a three-week period during and immediately after spawning, the Channel Cat crew prowls for the Loch Ness monsters of the Great Lakes.
Sturgeon, which trace to the age of the dinosaurs, may grow to more than six feet and weigh more than 200 pounds. They can live more than a century. Sturgeon have bony plates instead of scales, shark-like tails, pointed snouts, and four long barbels to locate prey in front of a downturned, suction-like mouth. The upper body is olive to gray, graduating to yellow or milky white.
The species fell victim to pollution, damming of their spawning streams, and commercial netting. Lake sturgeon provided a lucrative commercial fishery for caviar and smoked fish in the 1800s, and Lake Erie led the way on the Great Lakes. But, by the early 1900s, it was all but over.
About a decade ago the MDNR began a sturgeon rehabilitation and monitoring project with an eye to keeping the St. Clair population stable and to maintain a limited sport fishery.
A Michigan-licensed sport angler is allowed one sturgeon during a July16-through Sept. 30 season, taken from Lake St. Clair or the St. Clair River. Only a fish between 42 and 50 inches may be kept. All others must be released immediately.
On western Lake Erie, where sturgeon reports have increased in the last 10 to 15 years, the fish still are protected as an endangered species and any caught incidentally must be released.
The results of nearly a decade of St. Clair sampling showed it is the honey hole for sturgeon on the Great Lakes. It has a combination of clean water, a deep swift channel in the river, a river delta into Anchor Bay, and nearby broad shallows of the lake that make for a sturgeon heaven, according to Thomas. "Everything is just right for them here."
The strong flow of relatively clear upper Great Lakes waters sluicing down the St. Clair channel keeps the system cleansed and well-flushed. Sturgeon do not do well in polluted waters.
But a few sturgeon spawning sites also have been identified in the Zug Island reaches of the Detroit River. These usually are old ship-ballast beds and beds of coal clinkers and cinders discarded from coal-fired boilers on old lake freighters.
Thomas estimates that St. Clair waters harbor 10,000 to 20,000 fish. "It became obvious that this population in Lake St. Clair and the St. Clair River is far more abundant than on any of the Great Lakes. [But] there is a lot of movement."
Based on recapturing of tagged fish, the St. Clair fisheries station has established that a strong northward movement of sturgeon occurs into southern Lake Huron. The province of Ontario allows a limited commercial sturgeon trapnet fishery, and fish also are incidentally caught when netters target walleye, yellow perch, and whitefish, Thomas said. The southern movement of sturgeon from the St. Clair region is not as strong, the biologist noted. But a tagged St. Clair fish was recaptured in Lake Erie off Huron, Ohio.
Jeff Tyson, supervisor of fish management at Ohio's Lake Erie Fisheries Research Station, said that western Lake Erie may be a nursery ground for some of the St. Clair spawning stock. That, he added, is based on reports of juvenile tagged sturgeon that have been filed with the Sandusky fisheries office. Sturgeon catches should be reported by calling 419-526-8062.
The set-line tactics used by the MDNR crew generally target sturgeon as short as 20 inches and as long as 74 inches. The latter fish weigh around 100 pounds and likely are more than 50 years old, said Thomas. The oldest fish in the modern sampling record was in its early 70s.
"Any fish over 50 years old is pretty old for here. We've handled over 1,500 sturgeon here and 125 pounds is the largest we've sampled."
Tyson, who accompanied Thomas's crew last week, said that the Sandusky fisheries office usually receives 20 to 30 sturgeon reports a year. A catch report should include any tag numbers, the fish's length and weight if possible, and date and place it was caught - and released.
Two sturgeon catches have been reported at Sandusky so far this year, and one fish was picked up in survey gear run by the Ohio Division of Wildlife.
No sturgeon were reported in Ohio survey gear from 1969 to 1995, "but they started showing up in 1996," Tyson noted. "In western lake Erie finding a sturgeon is like finding a needle in a haystack."
Next spring, Tyson said, Ohio biologists hope to place some sturgeon set-lines in the Maumee River in hopes of measuring and tagging sturgeon believed to be running there. Repeated reports of sturgeon in the river have surfaced in recent years, including a five-footer that was caught by accident and released by a sport angler in 2000.
Maybe biologists will use gobies for bait.
"We've got plenty," Tyson said.