Water changes: high and low, hot and cold

Winter and fall: rain and floods

The water in our river systems flows from several sources: glacier melt, snowmelt, and rainfall.

In general, scientists predict the weather will shift towards less snow and more rain during the fall and winter. This could mean more flooding, which has many negative effects for salmon. Flooding can displace or damage salmon egg clusters or suffocate eggs under sediment. It can also cause erosion that blocks streams or removes important features of the waterside habitat.

Less snowfall in the winter also means the mountain snowpack will melt away earlier in the year. This brings lower flows and less cold water during the hottest days of summer.

Summer: low water levels

Low water levels can create problems for adult salmon as they migrate upstream. Salmon might get stuck in shallow areas or behind barriers, even where they can pass in higher-flow times. They could be delayed or prevented from reaching the spawning ground. This will lead to fewer salmon spawning successfully.

Reduced flows during the spawning season can also make a habitat less ideal for eggs and young salmon. Slower water can concentrate sediments in certain areas. Low flows can mean less oxygen in the water. This is especially dangerous in stagnant or isolated pools. If the oxygen in the water gets too low, it can stress or kill the fish. Lower and slower water also tends to be hotter.

Hot water

Most climate change predictions say the air temperature will increase by 2 to 4 °C (or more) by the year 2100. Warming air will lead to warming water, and water that’s too hot can stress or even kill both young and adult salmon. Egg survival and development are also affected by higher water temperatures. Water temperatures over 20 °C are dangerous for salmon.

Glaciers

Glaciers act as giant ice cubes providing cool water during the hottest summer months. In the Babine system of the Skeena watershed, tests were done to look at glacier melt and stream temperature. These tests found that streams with 10% glacier coverage are 5 °C cooler than streams without glacier melt. But glacier melt doesn’t only provide cooler water. Glaciers also provide extra water during the hottest times.

Dangerous heat

In 2019, a drought in watersheds around Prince William Sound in Alaska killed thousands of pink salmon before they could spawn. A study done on this event found that watersheds with glacier melt had more successful spawning salmon than rain-based watersheds. The glacier melt helped keep the water flowing and cool during a drought. Watersheds with glacier waters are less likely to have heatrelated mass fish-kills.

Managing water

These water changes are already impacting salmon. Studies of Chinook show fewer salmon surviving in years with large fall/ winter floods or low summer flows.

To maintain healthy salmon populations, we must manage peak-flow and low-flow events. Good water management will be critical for adapting to climate change.

This means ensuring that there is enough water in rivers to keep the ecosystem healthy based on climate change projections. It also means working to restore and protect salmon habitats. Good quality habitat can ease the stress of extreme high and low flow events on salmon.

Habitat restoration

Habitat restoration plays a crucial role in helping Pacific salmon populations cope with climate change. Restoration projects use many strategies to enhance and restore degraded spawning and rearing habitats. The goal is to provide better conditions for salmon to complete their life cycle successfully.

Restoring stream channels that once provided high-quality habitat for salmon.

Habitat restoration includes Improving in-stream “structures,” like adding dead wood to streams to provide shelter and food for salmon.

Creating or enhancing side channels and floodplains to expand habitat.

Reducing stranding

Habitat restoration is very important to reduce juvenile stranding. Stranding is when fish become trapped in isolated pools or very lowflow areas. Stranding is a serious problem for juvenile salmon when the water levels get low.

Habitat restoration projects can remove or modify barriers in the streambed to restore natural stream channels. This allows salmon to move more freely. These efforts can reduce the risk of juvenile salmon becoming stranded.

KLRD is collaborating with other Nations to restore salmon habitat in the Skeena Estuary. This project will try to reduce stranding of juvenile salmon due to highway and rail infrastructure.

Rock weirs

A rock weir consists of rocks or boulders carefully placed in a specific pattern in the water. Rock weirs can be used to modify the streamflow to create better conditions for salmon. For example, a weir can add variations to a stream’s flow, like deeper pools and riffles. Providing a diversity of habitats and stream features is important. Salmon need different types of habitats at different points in their life cycle.

You can see a rock weir in action in Kleanza Creek Provincial Park! KLRD installed two V-shaped rock weirs in 2020 to slow down flows. This allows spawning substrates (small rocks and pebbles) to gather on the streambed as the water flows over the weir rocks. Pink salmon were recently seen using the structures for spawning!

Overwintering pond

An overwintering pond is usually close to where salmon naturally spawn and rear. It is a calm area of water connected to a stream or river through a small inlet and outlet channel. This provides a constant flow of water into and out of the pond. An overwintering pond maintains good oxygen levels and prevents stagnant water.

KLRD is beginning a new study to establish an overwintering pond in Gitaus!

Estuarine and nearshore habitats

Estuaries and nearshore habitats are very important for salmon. These habitats support salmon during their transition from freshwater to the ocean and vice versa. Marshes, wetlands, and eelgrass beds are some key habitat types where salmon find food and refuge from predators. These habitats are especially important for the growth and survival of juvenile salmon.

Saltmarsh

The conservation and protection of saltmarsh habitat is critical to our salmon. Salmon smolts experience changes in their bodies and behaviour as they prepare to migrate to the ocean. But these changes take time. Saltmarshes provide an in-between habitat of semi-salty brackish water. This gradual change in the salt level of the water helps the young salmon adjust to the marine environment. Saltmarshes also offer shelter for juvenile salmon, protecting them from predators.

KLRD is part of a team developing Salt Marsh Monitoring Protocols. These protocols will direct future plans for field-based projects within the Skeena Estuary. They will also help restore and protect saltmarsh habitat.

Eelgrass

Eelgrass is a seagrass species that forms dense underwater meadows in shallow coastal waters. The long, ribbon-like leaves of eelgrass provide habitat for a wide variety of marine species. Eelgrass beds are a key habitat for juvenile salmon as they enter the ocean. These areas provide them with rich feeding grounds and shelter from predators.

KLRD is part of a team developing the North Coast Eelgrass Monitoring Strategy. This project will collect important information on how industrial development is affecting eelgrass. The goal of this strategy is to protect Kitselas’s most valued resource, salmon.