Studying sturgeon enhancement in Manitoba
Research is being performed near Manitoba Hydro’s 78-MW Pointe du Bois project to determine methods to enhance lake sturgeon spawning in the tailrace area.
This research is part of the utility’s Lake Sturgeon Stewardship and Enhancement Program. The program has been ongoing for more than a decade to maintain and enhance lake sturgeon populations in areas affected by Manitoba Hydro’s operations. Lake sturgeon inhabit almost all the waters where the utility operates generating stations. The species is under review for listing as endangered under Canada’s Species At Risk Act.
The Lake Sturgeon Spawning Enhancement Trial, under way at Pointe du Bois on the Winnipeg River, is intended to investigate methods of creating habitat downstream of hydro stations that is suitable for lake sturgeon spawning. This project was selected because of the relatively abundant lake sturgeon population, says Marilynn Kullman, environmental specialist with Manitoba Hydro.
During spill years, spawning is concentrated below the spillway and in specific areas below the powerhouse. During non-spill years, sturgeon spawning is more widespread below the powerhouse. Much of the habitat just downstream of the powerhouse has suitable depth and velocity for spawning but has little flow diversity and turbulence, lacks suitable substrates for egg incubation, and can lack low-velocity staging areas when all the generating units are operating.
To provide suitable substrate and flow diversity for spawning, Manitoba Hydro constructed shoals. Shoals consist of boulders and cobbles (to provide interstitial space for egg incubation) placed by divers in an 8-meter-by-8-meter area. Four large boulders were placed just upstream of each boulder/cobble bed to create turbulence and flow diversity to attract spawning sturgeon. One shoal was built in 2009 and three in 2010. One shoal is 25 meters from the powerhouse, another is about 5 meters from the powerhouse, and two are within a few meters of the powerhouse.
Egg collection mats were deployed on or near the shoals and throughout the accessible portions of the spillway spawning habitat. The presence of eggs on a mat indicates lake sturgeon are spawning in that location or slightly upstream. Three of the shoals were monitored for two hours a day throughout the spawning period using a sonar camera mounted to a boat. (The fourth shoal could not be monitored because of the instability of the boat and camera at that location.)
During sturgeon spawning in 2010 (mid-May to early June), the Pointe du Bois station was not spilling water. None of the egg mats deployed on top of the spawning shoals collected eggs, but egg mats in close proximity to one of the shoals captured large numbers of eggs. Egg mats in close proximity to two of the shoals captured a smaller number of eggs.
Lake sturgeon were observed via sonar camera to be on and just adjacent to the spawning shoals at the beginning of the spawning season. As water temperature increased, the number of sturgeon and the level of activity increased.
Despite the activity and presence of eggs, Manitoba Hydro was unable to make conclusive observations of lake sturgeon spawning on the shoals. Thus, the utility plans to continue monitoring the shoals over the next few years, under different flow conditions and operating scenarios. The results of this research will be applied to the development of future hydro stations and may be used to improve lake sturgeon habitat near existing facilities.
Study shows boost in salmon survival at The Dalles Dam
A new $51 million wall constructed in the Columbia River below The Dalles Dam significantly boosted survival of juvenile salmon and steelhead migrating downstream past the dam in 2010, according to research presented at a major gathering of fish scientists in Portland.
Studies showed that 96 percent of yearling chinook salmon passed the dam safely, up by 4 percent over similar tests in 2004 and 2005. Studies also found that 94 percent of sub-yearling chinook passed downstream safely, up by 7 percent. Also, 95 percent of steelhead survived past the dam, although past steelhead survival is not available for comparison. The data was presented at the U.S. Army Corps of Engineers’ Anadromous Fish Evaluation Program Annual Review conference in Portland.
Survival targets established by the National Marine Fisheries Service’s 2008 biological opinion on the operation of the Federal Columbia River Power System for salmon and steelhead listed under the Endangered Species Act are 96 percent for yearling chinook salmon and steelhead smolts and 93 percent for sub-yearling chinook salmon.
Fish biologists with the Corps’ Portland District, which operates The Dalles Dam, credit the construction of the wall between spillway bays eight and nine for much of the increase in survival. The wall is 10 feet wide and 850 feet long and helps guide young fish passing through the dam’s spillways into the safest part of the river, away from predators.
About 80 percent of juvenile fish pass over The Dalles Dam’s spillway. The new wall directs the flow of water from the spillway to the deepest part of the river’s channel, moving young fish away from low flow and shallow areas where they are at risk of predation from other fish and birds. Northwest power consumers will repay the costs of the wall over the coming years.
Nearly 400 dams to be surveyed in Maine salmon habitat areas
The National Oceanic and Atmospheric Administration (NOAA) plans to conduct surveys of a total of 396 dams in three Atlantic salmon habitat recovery units in Maine.
This work will involve developing a dam owner survey method and a barrier restoration implementation plan, as well as conducting surveys of the mostly small dams for NOAA’s Northeast Regional Office in Gloucester.
Atlantic salmon are listed as endangered under the Endangered Species Act. Dams obstruct migration of these fish; diminish access of fish that can serve as buffers from predators; and degrade spawning and rearing sites by altering natural hydrologic, geomorphic, and thermal regimes, NOAA says.
Dams to be surveyed include an estimated 211 in Merrymeeting Bay Salmon Habitat Recovery Unit, an estimated 111 in the Penobscot Bay Salmon Habitat Recovery Unit, and an estimated 74 in the Downeast Coastal Salmon Habitat Recovery Unit in eastern Maine. Each of these units has its own unique geology, water chemistry, climate, hydrology, and anthropogenic influences.