Studies unveiling new info about sturgeon population

While still in their preliminary stages, two studies have been giving a clearer picture of the sturgeon population in both the Namakan reservoir and Namakan River.
“First and foremost, we’re learning new information about a fish population we knew absolutely nothing about going into this,” explained Darryl McLeod, area biologist for the Ministry of Natural Resources who has been heading one of the studies that’s tracking and assessing the sturgeon population on the Namakan River.

“There has been no previous work done on lake sturgeon in the Namakan River, or in the Namakan reservoir, so we know very little about the fish,” he noted. “Through this study, we’ve gained a lot of insight that’s going to help us manage that fish population.”
The first study, which is being done by the MNR, arose largely because of the three hydro dams the Ojibway Power and Energy Group proposed in December, 2006 to build along the Namakan River.
Sturgeon tagging, genetic assessment, and telemetry studies are part of the 18 in the OPEG’s environmental field studies plan, which is being developed as part of the hydro screening process.
“What the proponents of the hydro power projects would do is take all this information and develop an environmental screening report as part of their environmental assessment process, and that’s where they look at mitigation and all the values out there that they have to consider,” McLeod said.
“So that’s the main reason why work is being done on the Namakan River.”
Coinciding with the MNR’s study of sturgeon is one being done on the Namakan reservoir, the five big lakes upstream of Rainy Lake shared between Ontario and Minnesota, which is being headed by Steve Windels of Voyageurs National Park in Minnesota.
Since a “large chunk” of the Namakan reservoir is in Voyageurs, the U.S. National Park Service has a responsibility to monitor species like sturgeon that are listed as a special concern, Windels explained as to why they became involved with studying the sturgeon population.
“It’s important obviously when you have a fish that’s managed across an international boundary,” he noted. And in this case with the proposed hydro development on the Namakan River, the National Park Service wanted to get some more information about what the potential impact may be to sturgeon that utilize water on our side of the border.”
Sturgeon, which can grow to more than 100 pounds and live for decades, were greatly reduced in numbers by the early 1900s. Currently, they are considered a species of special concern in both Ontario and Minnesota.
The population is now recovering in the basins stretching from Rainy River to Lake of the Woods, to Rainy Lake, to Seine River and the Winnipeg River, and the St. Croix River in Minnesota.
“Sturgeon are a species at risk all around the world,” said Kevin Peterson of the Minnesota Department of Natural Resources, which has a hand in managing fish throughout the state.
“We are fortunate to have some populations of sturgeon here in the border waters unlike many other places in this part of this country, this part of the world, where they’ve disappeared,” he added. “So any information that we can gain about the status of the population will help us make management decisions.”
Peterson said sturgeon are a sensitive species and vulnerable to exploitation due to their slow growth, the extended time it takes for them to mature, and because they don’t spawn annually.
“They require a little bit more management attention, if you will, than most other species that we work with,” Peterson noted, adding that because of this, if there is a problem, researchers may not know of it for a long time.
But the sturgeon on the Namakan reservoir are not like the fish on the Rainy River, noted Windels.
“[Rainy River] is a heavily-utilized recreational fishery, and everyone knows about the great sturgeon fishing in Rainy River,” he said. “But that just doesn’t happen in the Namakan reservoir, and as a result, we just don’t have much information about what’s happening with that population.”
Besides tagging fish, both studies are using acoustic telemetry to track fish. A total of 60
transmitters were surgically implanted into different sturgeon and in 26 locations, submersible receivers were placed.
If a fish carrying a transmitter swims within 500 metres of one of these receivers, the receiver will detect and record the date, time, and which fish it was.
By doing this, the researchers could see the movements of fish up and down the river, and into the lake, and how any of the proposed dams might impact their movement.
Using this method, there were “lots of detections,” McLeod said—1,391,970 to be exact.
“So that’s what we’re doing right now is trying to analyze all of that data,” he added. “How many fish each receiver has detected, how many receivers each fish goes by, that sort of stuff.”
For example, one of the fish they tracked using the transmitters included a mature 32-year-old female who was ready to ready to spawn, McLeod remarked.
“[She] probably spawned below Ivy Falls and then went all the way downriver, down over the big High Falls, and then all the way out to Namakan Lake. So that’s about 30 km in distance,” said McLeod, noting that in five days the fish would have travelled about 20 km.
Other fish also were recorded making similar journeys.
“So that’s one of the findings now, that they move up and down the entire river,” said McLeod. “They move fairly quickly when they do move.”
The research was able to record seven fish going over High Falls, a 20-foot drop, he added, and also saw sturgeon choose a back channel to go back upstream using staggered, gentler rapids.
“We went into this study not even knowing that they used this back channel and how they use it, what time of year they use it, and now we’ve been able to confirm all that,” McLeod enthused. “They go up and down the back channel, and they use it probably more than we ever thought they did.”
Besides confirming the extent of sturgeon migration, the study also has shown sturgeon travel through shallow rapids and falls more often during the night, as well as avoid these shallow rapids and movements during winter months—instead preferring to spend their winters in lake environments.
While they started with 34 fish outfitted with transmitters in the MNR study, 11 fish with transmitters from the American study made their way up into the Namakan River, noted McLeod. Conversely, about half of the fish the MNR had attached transmitters to travelled into American waters.
Almost 550 sturgeon also were tagged for the studies, and tracking these tagged fish has confirmed what the acoustic telemetry results show: that the sturgeon population travels far along and in between the Namakan River and lakes, and that they are an internationally-shared fish stock.
As part of the study, each fish that was caught also was assessed for both a population estimate and genetic works testing, McLeod explained.
“Both the telemetry and genetics suggest that we’re dealing with one population of sturgeon,” he said of the findings. “Not one in the river, or one in those little lakes in the river.”
The genetic testing also showed the Namakan sturgeon population was genetically similar to those in Rainy Lake, but not at all similar to the Lake Superior sturgeon.
The study also has allowed the MNR to look and see how well the sturgeon population has been recovering from the over-fishing that caused their greatly-reduced numbers by the 1900s.
Altogether there were 349 sturgeon that were caught and aged, noted McLeod.
“We’ve had essentially consistent annual recruitment in that population . . . so the fishery is pretty healthy, but it is recovering,” he said.
But while short-term goals for seeing the sturgeon population recover have been met, McLeod stressed they need to start seeing older fish to meet the long-term goals and for the sturgeon population to be considered fully recovered.
While the MNR study mainly was started because of the proposed dams, it also will contribute to the provincial management of the species.
“Because lake sturgeon are species of special concern across Ontario now, there’s MNR folks preparing a management plan for lake sturgeon across the whole province, so that the information we get from this study can be used to creating a management plan for the whole province also,” McLeod explained.
With the MNR study beginning in spring of 2007, the VNP study is a year behind, noted Windels, but added much of the data collected has echoed the findings of the MNR.
“I think the main thing that we’ve found, so far, is that fish within the Namakan reservoir are moving pretty freely between the river, almost all the stretches of the river on the Ontario side and throughout the reservoir side, both on the U.S. and on the Canadian side,” said Windels.
“I think we’ve seen certainly in the first year that this is a shared fish stock.
“We’re starting to get some ideas about what are some of the alternative spawning sites outside of the Namakan River, and again about how fish are moving throughout the reservoir, and this is not actually that surprising given what other people know about lake sturgeon from other places.
“They’re big fish and they do move around a lot, but it is just always fascinating to see how much space that they can cover, moving 90 km in the span of a couple months.”
This year, VNP will continue to monitor sturgeon movement, with more netting, tagging, drawing blood for genetic testing, and identifying key spawning habitats. Windels said the study will go to 2011 or 2012.
As for the MNR study, it still has a few more years to go, noted McLeod, with more data collection, reports, and data analysis.
For now, a big highlight of the studies has been how both the Canadian and American sides have been working together to gather information.
“This study is sort of unique in that it crosses the international boundary,” said Windels. “We’ve co-ordinated the studies to such an extent that essentially we’re running all the same equipment and basically doing things the same way so that we’ve doubled the number of fish that we have transmitters in, and really doubled the amount of information that we’re getting out of this.
“Which is really beneficial to both sides.”
The two studies mesh together very well, agreed McLeod, since both sides essentially are tracking the same population.
“So we’re going to be actually putting all the information together when it ends and possibly one big project,” he said.
“Sturgeon are a shared resource,” added Peterson. “The international border goes down the river of Namakan Lake, approximately the middle, and certainly those fish don’t know where that boundary is.
“So it just makes sense for us to work together to try to manage this species.
“It’s the sort of thing that probably no one agency could have undertaken themselves because of the fact that these fish do move around, and swim back and forth across that boundary, and even between the different lakes,” he remarked.