Tue, 19 Feb 2019

Lake Aeration in B.C. – Another Tool in the Toolbox – by Brian Chan

Horseshoe lake in Roche Lake Provincial Park with aeration unit operating mid-winter

British Columbia is blessed with an abundance of freshwater resources. Over 16,000 lakes alone are found scattered throughout the province. Our lakes offer some incredible fishing opportunities, and those located in the interior regions of the province are often glowingly referred to by anglers in the know as the best blue ribbon trout fisheries found anywhere in North America.

The backbone of our lake fisheries are those which provincial fisheries managers refer to as small lakes. They include those that are less than 2200 acres in surface area and with the vast majority being less than 220 acres. Furthermore, stocked small lakes play a huge role in creating and sustaining angling effort in the province. Approximately 800 lakes are stocked annually by the Freshwater Fisheries Society of BC. Analysis of long term angler effort data reveals that stocked small lakes support over 50% of the total annual freshwater fishing effort in the province.

So why are small lakes such an attraction for anglers? Much of their popularity comes down to where they’re located. The interior regions of the province from the Okanagan through to the Peace River are richly endowed with productive or nutrient-rich lakes. Many of these waterbodies were created several thousand years ago when the last of the glaciers receded, leaving behind scoured-out depressions that filled with water. Their shallow nature and fertile basins combined with a long, hot growing season proved to be the perfect combination for growing trout. There are also a number of nutrient rich lakes that are found on Vancouver Island and the surrounding Gulf Islands that have been managed for recreational trout fishing for decades.

Ecologically, many of these nutrient rich small lakes are classified as being in a eutrophic state. These lakes are typically shallow, with maximum depths of less than 50 ft and average depths of less than 15 ft. They are often landlocked or have only intermittent or seasonal stream connections. Because they are rich in nutrients, they are abundant in aquatic plants and invertebrates. Eutrophic lakes can be extremely productive and have the capability to grow trout and char very quickly and to large sizes. However, the same features that make accelerated growth possible in the summer can make it difficult for trout to survive over winter. Some of our most popular interior trout lakes are marginal in terms of their ability to support trout through the colder months due to a drop in dissolved oxygen levels Thousands of small trout lakes in BC’s interior freeze over for 4 to 6 months each winter. During that ice-covered period, the aquatic plants that grew through the open water seasons die off from lack of sunlight. Dissolved oxygen in the water is used up as this plant matter decomposes. As winter progresses, the volume of oxygenated water decreases to levels that become too low to support trout life, which results in a winterkill.

There are also small lakes located in the coastal regions that suffer from severe oxygen depletion during the summer months. This affects the ability of trout to survive as well as having impacts on the quality of the water for domestic use and other forms of aquatic recreation.

Lake aeration and artificial circulation is a tool that allows fisheries managers to improve over-winter trout survival in interior lakes susceptible to winterkill and provide summer refugia in eutrophic coastal lakes. In order to understand how aeration works, one needs to be aware of the seasonal changes that occur in a small lake, and how thermal stratification affects where trout can live in those waterbodies at various times of the year.

Eutrophic lakes undergo complete mixing, also known as turnover, in the spring and fall. In the spring, the lake mixes when surface temperatures become similar to that of the deeper water. Several days of wind will completely mix the entire water column, the end result being a lake fully charged with oxygen.

As summer progresses, warm air temperatures heat up the upper layers of lake water, but the energy of the sun can only penetrate so deep: beyond that depth, the water remains cold. The upper layer of warm water is referred to as the epilimnion, and the colder, deeper water is the hypolimnion. The transition zone that separates the epilimnion from the hypolimnion is known as the thermocline. The thermocline acts as an invisible barrier to the mixing of the two layers, leading to steadily decreasing levels of dissolved oxygen in deeper waters and an overall reduction in water quality.

In the late fall, as surface temperatures cool down to match the temperature of deeper water, eutrophic lakes will mix again. Brisk winds circulate the entire water column and result in the entire lake becoming well oxygenated and ready for winter.

History of Lake Aeration in B.C.

Lake aeration and artificial circulation projects were first developed in the early 1960s to address winter oxygen concerns on a number of lakes in the Okanagan and Thompson/Nicola regions. Electric or diesel powered air compressors were used to deliver oxygen through an airline and diffuser system placed in the deep part of the lake basin. Referred to as de-stratification systems, the constant stream of air bubbles created an upwelling circulation that brought deeper water to the surface where it was exposed to the air/water interface. Limited oxygen absorption into the water occurred with the release of the diffused air as well as at the lake surface.

The cost to operate and maintain these diesel and electric units proved to be very high, so other aeration/mixing systems were tested during the 1970s. Wind and solar-powered aeration units provided inconsistent results and were not well-suited to the cold, interior winter climate. It became clear that a reliable source of power was needed to successfully operate any aeration or circulation system. In the 1980s, small electric-powered floating aeration units were tried on numerous small interior lakes. These units consisted of a sealed, submersible electric motor equipped with a small propeller. They were positioned on a wooden float, and the unit suspended just below the surface of the lake. The unit pulled water from the surrounding area up to the surface along with spraying of water into the air where oxygen transfer and mixing occurred. These systems were less expensive to operate and simpler to maintain than previous models and are still used in many BC lakes today. They are typically turned on after fall turnover and then operated through the winter months. Anglers fishing aerated lakes will be familiar with the orange safety fencing that is placed at a distance around the open water surrounding the operating aerator. This fencing and accompanying signage is placed to keep anglers and other recreationalists at a safe distance from any potential thin ice.

Hypolimnetic Aeration

At the same time that electric-powered aerators were being placed in BC’s interior lakes, specific lakes on southern Vancouver Island and Salt Spring Island were being assessed for aeration suitability. These lakes were undergoing cultural eutrophication from rapidly increasing agricultural and residential development within their watersheds. Summer algal blooms, deteriorating potable water quality, and oxygen depletion concerned both fisheries and water management agencies.

An appropriate aeration system could sustain angling opportunities while improving water quality for domestic use and other forms of aquatic recreation. The first hypolimnetic aeration units were installed on Long Lake near Nanaimo, and on St. Mary’s Lake on Salt Spring Island. These were huge units requiring helicopters to lift them in place. They consisted of two large galvanized steel tubes attached to a floating box or separator raft. The tubes hung straight down and extended to the deeper parts of the hypolimnion. A diffuser with air stones was situated in the very bottom end of the intake tube, and a hose system supplied a steady stream of air to the diffuser by way of an electrical compressor. The air bubbles rising up the intake tube would create a current of water pushing to the top of the tube and then flowing down the exit tube, which was situated next to the intake tube within the separator box. This continuous circulation of aerated water resulted in marked increases in the oxygen content within the hypolimnion, while at the same time not affecting or breaking through the thermocline. The result was improved deep water fish habitat as well as reduced blue-green algal blooms which were the cause of poor water taste and quality.

Role of the Habitat Conservation Trust Foundation in Lake Aeration

Lake aeration systems were proving to be effective for both increasing winter and summer survival of trout as well as improving water quality. Unfortunately, the high cost to build, install and operate these systems meant the provincial Ministry of Environment could not continue to expand the program. It was then that the Habitat Conservation Trust Foundation (HCTF) stepped up to the plate. HCTF began in 1981 as an initiative of anglers, hunters, trappers and guide-outfitters who were willing to pay more for their licence fees if this additional funding was used to enhance fish and wildlife populations and to acquire important fish and wildlife habitat. To date HCTF has invested over $700,000 in the installation of aeration systems and provided more than $3 million dollars for the operation and maintenance of these units. The provincial lake aeration program is just one of the many habitat improvement projects that would not exist without the financial support of the Habitat Conservation Trust Foundation and licenced anglers in BC.

The Current State of Lake Aeration in B.C.

Currently, there are 20 aerated lakes across 5 different regions of the province. 4 of these are hypolimnetic systems (similar to St. Mary’s Lake), and the remaining 16 are the surface mounted de-stratification style units. Annual operation of these systems helps to sustain recreational fishing opportunities that would not otherwise be available.

For example, Red Lake located NW of Kamloops is a very popular rainbow and brook trout fishery that, prior to the installation of a hypolimnetic aeration system, would winterkill on a regular basis. Today, there are approximately 8000 angler days per year spent on this lake, with about half of that effort occurring during the winter months. This hypolimnetic aeration unit uses the latest technology which includes removing nitrogen from the air being pumped into the diffuser tube which results in close to 100% oxygen versus normal air which contains 23% oxygen. The end result is increased oxygen transfer into the water column. These hypolimnetic units also have the benefit of not creating open ice on frozen lakes. While these units are still often fenced off with safety netting, the liability concerns are significantly reduced. Simon lake is located in the southern Cariboo region just north of the town of 100 Mile House. Simon is an extremely productive waterbody that is managed for quality fishing. A surface mounted aeration unit operate through the late fall and winter months to sustain fish that reach in excess of 10 lbs. The opportunity to catch a trophy sized rainbow attracts over 1000 angler days a year to this small lake.

Other aeration projects have not been as successful. St. Mary’s Lake received the first hypolimnetic systems back in the early 1980s. It operated adequately for a number of years, but when the original unit was replaced with a larger system, the results were not as expected, and the system was eventually shut down.

Aeration is not a magic bullet to solve all fish survival and water quality issues in eutrophic lakes. It is one tool in the tool box that fisheries managers can consider for specific water bodies when conditions are right.

Brian Chan has been fortunate enough to live and work for the past 35 years in Kamloops, British Columbia. It is here that Brian, as a provincial fisheries biologist, managed the recreational stillwater trout fisheries in the Thompson/Nicola Region, and developed his fishing skills. Brian’s lifelong passion for fly fishing has resulted in his spending literally thousands of angling days on these world class waters. He has shared his extensive knowledge of aquatic biology, trout ecology, entomology, and lake fly fishing tactics with others, through magazine articles, books, and instructional DVDs. Brian has been featured on many TV fishing shows and is currently a regular guest on Sport Fishing on the Fly and co-host of The New Fly Fisher.

Tue, 12 Feb 2019

Keeping watch for invasive mussels

Nerissa Abbott, a CKISS Invasive Species technician using a plankton net at Gyro Park in Trail to collect samples that get sent to a lab for testing. The lab will test for free-swimming microscopic mussel larvae, called veligers.

Vigilance is the price of keeping our waters free of invasive mussels. According to the 2018 interim report on the Provincial Mussel Defence Program, of the 38,000 watercraft inspected during the 2018 operating season 25 boats were confirmed to have highly invasive zebra and/or quagga mussels. Luckily these mussel-fouled boats were stopped, as they were destined for waters all over BC!

To date, BC is still free of invasive mussels, and many groups such as The Central Kootenay Invasive Species Society (CKISS) are working hard to keep it that way. The CKISS and other HCTF-funded organisations are monitoring for the mussels across the province. From June through October 2018, the CKISS collected 350 samples at 34 sites within nine different high priority waterbodies. To date, the province has analyzed 812 samples from across B.C. and all have come back negative for invasive mussels.

Keep up the good work monitors!

Thu, 6 Dec 2018
Tags: Fisheries

HCTF Makes New Sturgeon Commitment

Sturgeon and 3 Fisherpeople

The Habitat Conservation Trust Foundation has made a substantial new commitment to white sturgeon in BC, which will see the foundation provide an additional $250,000 over the next 5 years towards projects that contribute to the conservation of sturgeon and associated habitat.

Starting in 2008, the Province of British Columbia introduced new conservation surcharges on licences to fish for sturgeon on the middle and lower Fraser River. The surcharge funds are directed to a dedicated account overseen by the Habitat Conservation Trust Foundation, to be reinvested in important work to sustain these sensitive populations.

The amount of revenue generated annually depends on the number of sturgeon licenses sold. Over the past 8 years, the average annual revenue from sturgeon surcharges was $250,000. In 2017/18, it was approximately $325,000.

In October 2018, the HCTF board decided to provide an additional $250,000 for sturgeon projects, over and above the annual amount generated through sturgeon angling surcharges. This means that HCTF will provide an additional $50,000 annually in new funding for sturgeon conservation projects for each of the next 5 years, starting in 2019.

“HCTF recognizes the unique value of sturgeon and the need to protect this irreplaceable species,” explains HCTF CEO Brian Springinotic. “We want to augment the already significant contributions of the sturgeon angling, guiding and scientific communities, who act as sturgeon advocates and ambassadors, citizen scientists, and, through license fees, financial supporters of conservation projects.”

Over the years, HCTF has funded a variety of sturgeon conservation projects in BC. Recent examples include long-term acoustic tracking of adult sturgeon and a collaborative project focused on the removal of ghost nets (read more).

Thu, 29 Nov 2018

Coquihalla River Rehabilitation Project Update

Crew working to break up boulder on Coquihalla River

HCTF is delighted to share an update from one of our more explosive recent projects, the Coquihalla River Summer Steelhead Migration Rehabilitation Project.

In the spring of 2014, an unfortunate combination of erosion, shifting of boulders and the settling of a failed bridge foundation introduced a new obstacle for summer steelhead attempting to access the upper 20 km of the Coquihalla River. The location of Othello Falls, combined with seasonal water levels, have always made this stretch very difficult to pass, but the 2014 events made this barrier almost fully impassable. Loss of access to the upper river threatened the long-term viability of this unique steelhead population. In response, a dedicated group of biologists, engineers, conservationists, and fisheries enthusiasts came together to make a plan.

Northwest Hydraulic Consultants was contracted to oversee modifications to the barrier. In September 2017, the team rappelled down the bridge at Othello Falls, drilled holes in the most problematic boulder, and used low-impact explosives to break the blockage into smaller pieces. Over the winter, high water flows redistributed the rocks, creating a more accessible passage for steelhead.

While it is still too early to assess the full impact of the rehabilitation work, preliminary results are encouraging, according to Mike Willcox, project leader and Fish Biologist with Ministry of Forests, Lands, Natural Resource Operations and Rural Development for the South Coast Natural Resource Region. His team conducted snorkel surveys both up- and down-stream of the barrier in late summer 2018 to determine the percentage of summer steelhead that successfully traversed the blockage. “Our observations indicate the works were at least partly successful in improving access at the barrier,” says Willcox. “As well, anglers were pleased with the fishery upstream of the barrier this season. We will continue to monitor fish movement each year past the barrier to determine whether any further works are required.”

The Coquihalla River supports one of only two natural, coastal summer-run steelhead stocks on the lower Fraser River. This stretch of river provides a rare opportunity for artificial fly-only summer steelhead fishing. From both a conservation and recreation viewpoint, individuals and organizations from across BC are very keen to support this important piece of habitat. HCTF is keen to follow the monitoring updates from the talented and creative folks on the ground and in the water at the Coquihalla River.

This project was supported by the Freshwater Fisheries Society of BC, the Steelhead Society, Kingfisher Rod and Gun Club, the BC Conservation Foundation, BC Parks and the Ministry of Forests, Lands, Natural Resource Operations and Rural Development.




Sun, 27 May 2018

Project Evaluation: Spring Site Visits

Dutch Creek Columbia Lake as viewed from the Hoodoos property
By Kathryn Martell and Christina Waddle

Project evaluation is a core component of HCTF’s grant programs. In addition to a thorough review of proposals and project reports, we conduct more in-depth evaluations of several projects each year. This assessment combines a detailed review of both financial and biological components of a project, ranging from questions about a project’s bookkeeping processes to a field day with the project leader to see the activities “on the ground”. These site visits provide us with an opportunity to better understand a project’s challenges and successes, to evaluate our conservation return on investment, and—best of all—to spend time with our project leaders somewhere outside in wild BC with an opportunity for them to tell us more about the projects they are passionate about.

One of the new interpretive signs funded with an HCTF Land Stewardship grant at NCC”s Dutch Creek Hoodoos property

HCTF staff had the opportunity to visit two of our continuing projects this spring. Our Conservation Specialist Christina Waddle attended the Official Trail Opening Ceremony at the Dutch Creek Hoodoos Conservation Area owned by the Nature Conservancy of Canada (NCC). Richard Klafki, Canadian Rocky Mountains Program Director for NCC, showed Christina some of the work that’s been accomplished with the Land Stewardship Grant from HCTF. This project included marking and improving the main loop trail and discouraging use of other informal trails on the property through directional signage and fencing. The other main component of the project was the design and installation of five educational interpretive panels. This will help meet NCC’s management goals for the property which include protection in perpetuity, providing a quality site appreciation experience, while limiting the effects of recreation on native vegetation and wildlife.

Evaluation Manager Kathryn Martell and Finance Officer Jade Neilson headed over to the Lower Mainland to meet up with provincial sturgeon specialist Erin Stoddard and his field crew for a day on the Fraser River. Now in its sixth year, the Lower Fraser White Sturgeon Telemetry Study is conducting long-term monitoring of adult sturgeon to gain a better understanding of movement patterns and habitat use of this Red-listed species in the Lower Fraser, Pitt, and Harrison Rivers. Although White Sturgeon is considered at risk, there is a limited catch-and-release fishery on the Lower Fraser River; a licence surcharge supports a dedicated HCTF fund for sturgeon research and recovery efforts.

HCTF Finance Officer Jade Neilson and project field technician Garrett enjoy some sunshine as they journey from one site to another.

Jade and Kathryn had a great day out on the water, with high flood conditions making it both challenging and interesting to retrieve and re-deploy the data loggers that record movements of individual sturgeon using acoustic tracking devices. It is surprising how little we know about this long-lived, large, prehistoric fish that is so important to local First Nations. This project is the first ever long-term telemetry study of sturgeon habitat use on lower Fraser River White Sturgeon, and it is already providing critical information about over-wintering sites, spawning areas, and development impacts, that is being used to improve fisheries and habitat management. In between hauling heavy equipment in and out of the boat, we had a chance to see some of the critical spawning areas being studied; to understand much more about the project’s study design, and how Erin and his crew have responded to many challenges (such as, what to do when your data logger is buried under 3 tonnes of log boom?) and learn about some of the complications of studying a fish that can live twice as long as humans and travel more than 125 km upstream and downstream each year in the ever-changing conditions of a large river system.

Field technician Garret preps a data logger before submerging in the river. IN the background, you can see an example of the battering some of these frames take from log booms.

Thank you to both Richard, Erin and Garrett for showing our staff the conservation work being accomplished with HCTF grants.

Tue, 27 Feb 2018
Tags: Wildlife

Whirling Disease Update

Whirling disease sampling


Last April, HCTF, FFSBC and the Province of British Columbia provided funding to hire a coordinator to lead the province’s efforts in preventing Whirling Disease from entering BC. Stephanie Whyte and her team sampled over 880 fish in the Columbia Basin for the presence of Myxobolus cerebralis, the parasite that causes whirling disease. The fish were sampled at six different sites:

  • Elk River
  • Premier Lake
  • Lower St Mary River
  • Koocanusa tributaries
  • Kootenay River (near Creston)
  • Columbia River (near Castlegar and Trail)

The team used sampling methods similar to those used in Alberta and by Parks Canada to create continuity in methodology in Western Canada. Because whirling disease is a reportable disease in Canada, Canada Food Inspection Agency collaborated with the Province of BC on a sampling methodology and to identifying priority sample sites in the Columbia Basin. The samples were sent to a FFSBC or a CFIA lab to test for the presence of Myxobolus cerebralis using PCR. All results came back negative for the presence of Myxobolus cerebralis.

In addition to testing for whirling disease, the team has developed effective decontamination procedures to help prevent the spread of the disease by human activity. They also created an Early Detection Rapid Response Plan (EDRR) to provide detailed direction on the decisions and actions required if whirling disease is detected in BC. This document is based on similar plans created for invasives such as Zebra and Quagga Mussels.

For 2018, the team have put together a plan that will continue to focus on areas of high human activity in and around the Columbia Basin.

Report Suspected Cases of Whirling Disease

While there are still no documented cases of Whirling disease in British Columbia, it has been confirmed in several locations in Alberta near the BC border. Fish infected with whirling disease may exhibit a “whirling” swimming behavior as the parasite attacks cartilage and impairs the nervous system. Fish may also show signs of physical malformations including head and tail deformities and darkened coloration near the tail area. If you see fish seeing any of these symptoms, please contact Front Counter BC Toll free: 1-877-855-3222; email: FrontCounterBC@gov.bc.ca