Wabamun Lake, a Fishery in Crisis

2024 Update

[Note: This piece is an update to a series of articles I’ve written about the Wabamun Lake fishery over the years and posted to my blog.  My last update was in 2021.]

For over 40 years, my wife and I lived near Wabamun Lake, about 60 km west of Edmonton, Alberta Canada. The lake was one of the reasons we chose the area to build our log home. Over the years, we visited the lake regularly, whether to fish, boat, swim or watch wildlife. It is where I taught my daughter to fish, starting with yellow perch and graduating to northern pike. In those years, the lake was a very productive fishery. I especially enjoyed fishing for lake whitefish through the ice in winter.

Indeed, lake whitefish were the main driver of a viable commercial fishery that occurred on the lake from the late 19^th through the 20^th centuries. However, because of declining numbers of whitefish, commercial fishing was closed in 2003.

Wabamun Lake, ~60 km west of Edmonton, Alberta Canada

Then along came the CN train derailment and oil spill in 2005. As a result of that catastrophe, the Alberta Government restricted fishing on the lake to catch-and-release (C&R) only to allow the fish populations to recover. The northern pike population recovered very well, with trophy-size pike being caught within a few years. However, the lake whitefish population continued to struggle. It was the worst hit by the oil spill; its reproduction apparently affected by the by-products of the breakdown of the oil in water.

In 2006 I became a founding member of the Wabamun Watershed Management Council (WWMC) because of my concern for the health of the lake. I thought that as a biologist I could make some contributions to the discussions about lake management. I ended up serving on the council for the last 18 years. Disclaimer: The opinions I share here are my own and not that of the WWMC or any other organization.

Walleye are a very popular sport fish in Alberta. Photo courtesy of Duane Radford.

Walleye Introduction

Over the years prior to the oil spill, the government made several attempts to introduce walleye (a highly prized sport fish) into the lake. But none were successful for a variety of reasons mostly having to do with the presence of a 1950s-built power plant using the lake as a cooling pond. That plant closed in 2010 and government biologists decided to try the introduction again. From 2011 to 2014, they released over a thousand mature fish and several million hatchery-raised fry into the lake. This time the stockings appeared to succeed as evidenced by some spawning that occurred in subsequent years. As a result, C&R-only fishing was extended to protect the growing walleye population. However, anglers began reporting that they were catching fewer and fewer trophy northern pike, and many of the younger pike they caught were skinny as if starving.

Fisheries biologist Stephen Spencer releasing mature walleye into Wabamun Lake in 2010

Fall Index Netting

To assess fish populations, Alberta Environment and Protected Areas (EPA) uses Fall Index Netting (FIN), where gill nets are set at various locations around a lake and left for several hours overnight. When the nets are pulled, the fish caught are counted and information is collected about gender, age, length and weight. From the number caught, a fish-sustainability index is produced for each species based on the “catch-rate” (fish caught/net night) and length of time the nets were in the water. The index is used to estimate the risk of each population not being able to survive. However, FINs are costly to the fish populations. Several hundred kilograms of fish are killed (edible fish from some lakes are donated to Indigenous and subsistence peoples). So, they are not done every year.

Since walleye were introduced to the lake, FINs were conducted in 2013, 2015, 2020 and most recently in September of 2023. After the 2020 FIN, the Alberta government finally allowed anglers to catch-and-keep some lake whitefish and burbot and a couple of walleye (less than 43 cm in length) with the purchase of a Walleye Special Harvest Licence.

(Note: The information presented here is my interpretation of the data available from EPA and analyzed by the Volunteer Biologists Group, an ad hoc group of retired Alberta Government fisheries biologists with many years of experience managing Alberta’s fisheries.)

2023 FIN

As I related in my 2021 post, the walleye introduction has appeared to upset the balance of fish populations in the lake. Walleye are especially aggressive predators and the larger fish appear to be preying heavily on the young of pike, perch, whitefish and their own kind. One age class seems to be dominating all others. The 2023 FIN shows this trend continuing. Six gill nets captured 159 walleye, 78 lake whitefish, 23 yellow perch, 19 white suckers and 17 northern pike.

Walleye

The mean catch-rate for walleye was 26.5 fish per net-night, up slightly from the 2020 rate of 25.5. However, the EPA analysis further broke the catch-rate into rates for mature (19.5) and immature fish (7.0). Such rates set a fish-sustainability index for walleye in Wabamun as “low-medium risk”. Table 1 shows the progression of walleye catch rates from 2013 (the first FIN since walleye stockings began).

However, the catch rate doesn’t tell the whole story. What is also important are the ages and relative health of the fish. Table 2 shows the age distributions of walleye during the four FINs that occurred since walleye were stocked. The red numbers follow a particular generation through all four FIN samples. As you can see, it dominated the other cohorts. It is made up of some of the 6.5-million fry stocked in 2012. What’s disturbing is the lower numbers of the other age classes, including those spawned since the last stocking.

In its 2023 FIN summary, EPA concludes there is “strong recruitment” of younger walleye into the mature population, based on length distribution. However, the age data (above) does not bear this out. A healthy population would have more fish in the lower age classes than in the mature ones, and that is not happening here. As in 2020, it appears that few new walleye are being recruited to the mature population that has one dominant age class. This suggests that little spawning is happening (the little happening likely caused by some of the mature fish stocked in 2010-2014) and/or the abundant larger walleye (stocked in 2012) are heavily preying upon the small walleye as well as young pike, perch and whitefish.

Several Wabamun lakeshore residents have reported that in the last 10 or more years, they have seen a lot less forage fish (minnows, young game fish) and aquatic insects in the shallow waters off their properties. Although anecdotal, these observations could indicate a lack of sufficient food to sustain fish populations. Indeed, anglers who have recently caught and kept walleye through their Walleye Special Harvest Licences have reported unhealthy fish with largely empty stomachs—suggesting starvation. Such starvation would cause slower growth rate (as is confirmed by the length data) and reduced reproduction (e.g., as a result of gonad absorption).

Northern pike are a large aggressive predator that is also prized as a sport fish.

Northern Pike

Since the walleye stockings, the northern pike population has been on a decline (see Table 3). In the 2020 FIN, only four fish were caught, a catch rate of 0.8/net-night. In 2023, 17 fish were caught for a catch rate of 2.5/net night. Although an increase, it was not enough to take northern pike out of the very high-risk category of sustainability. A species that once was the dominant predator in the lake, and produced many trophy-sized fish, has been having difficulty recruiting young fish into maturity for over ten years.

Lake Whitefish were once a very popular fish to catch and take home for a fish fry or smoke. Not anymore. Despite C&R-only fishing, the number of whitefish caught in FIN nets has declined steadily (Table 3). In the 2020 FIN, only 69 fish were caught. It slightly increased to 78 in 2023. But EPA did not provide a catch rate for this species.

Lake whitefish were once a very popular sport fish on Wabamun Lake. Since the oil spill and introduction of walleye they have not been faring well.

As of this writing, the sport fishing regulations for 2024-2025 have not been released. They are usually published well ahead of the beginning of the new season (April 1^st) but this year “more time is necessary to ensure that we get it right.” Until the new regulations are proclaimed, the 2023 regulations apply. Under those regulations walleye can only be harvested by people holding Class C Walleye Special Harvest Licences that allow an angler to take only two walleye a season under 43 cm in length. As I argued in my 2021 post, perhaps a more liberal harvest—for example, allowing an angler with a general licence to take 2 to 5 walleye a day during a 14-day window—would reduce the population to a more sustainable size. Or perhaps, we learn that Wabamun Lake cannot sustain a population of walleye, which it had not sustained for over 100 years.

It will be interesting to see if the new regulations address the reality of the situation on Wabamun, as well as other similarly managed lakes, and anglers are allowed to once again play their roles in fisheries management and take some fish home to eat while helping bring the fishery back in balance.