Is Lime Good for Salmon? A Deep Dive into Using Lime for Fish

Salmon are one of the most popular game fish species across North America. Anglers love targeting salmon, like king salmon sockeye salmon, chinook salmon and coho salmon, for their fighting spirit and delicious meat. As a result, many anglers look for ways to improve salmon habitat and growth. One question that often comes up is whether adding lime to lakes and rivers is beneficial for salmon populations. In this article, we’ll take a deep dive into the use of lime for salmon and what the science says.

An Overview of Using Lime for Fish

Liming involves adding ground limestone (calcium carbonate) to water bodies. It has been used for decades by fisheries managers seeking to improve water quality and fish habitat.

The main reasons liming is done are

• To increase water alkalinity and buffer acidity. Limestone raises pH and counters acidic conditions that can be harmful to fish.

• To add calcium. Calcium is an essential nutrient for bone and scale development in fish.

• To precipitate phosphorus. Phosphorus can cause excessive algae and plant growth. Adding lime binds to phosphorus making it unavailable.

• To support zooplankton growth. Small crustaceans called zooplankton are a key food source for young fish. Liming can increase zooplankton numbers.

• To reduce metals toxicity. Metals like aluminum can become toxic to fish when pH is low. Liming reduces metal solubility.

So in theory, adding the right amount of lime at the right time and place can create a more hospitable environment for game fish like trout and salmon. But what does the research say specifically about using lime for salmonid species?

The Impact of Liming on Salmonids

A number of studies have investigated the effects of liming on salmonids like salmon and trout. Here are some of the key findings on how altering pH and calcium levels with lime impacts these fish:

• Survival of salmonid eggs increases substantially when pH is raised from acidic to neutral levels (6.5-7.5) through liming. Researchers found significantly higher egg-to-fry survival rates for brook trout and Atlantic salmon when limed vs unlimed.

• Growth rates are generally higher for juvenile salmonids when moderate amounts of lime are added. One study on rainbow trout found fish grew faster when lime was added compared to untreated water.

• Higher pH and calcium has a positive effect on salmonid gill function and development. Healthier gill tissue improves respiration, ion balance, and resistance to disease.

• Salmonid density tends to increase in limed streams and lakes compared to unlimed waters with similar habitat. More natural reproduction is observed after liming acidic waters.

• Diversity of food organisms like aquatic insects and zooplankton increases with moderate liming. This provides salmonids with more prey sources.

• On the other hand, excessive liming and overshooting neutral pH can have negative impacts. pH levels above 8-9 and high turbidity from liming may cause fish avoidance.

So the consensus is that salmonids do tend to benefit from liming practices that elevate pH and calcium concentrations to moderate levels. Liming acidic waters appears to create a more favorable environment for salmonid survival and growth. However, care should be taken not to over-lime which can swing water chemistry too far in the other direction.

Considerations for Using Lime to Manage Salmon

If you’re interested in liming a stream, lake or pond to improve salmonid habitat, keep these tips in mind:

• Accurately test pH, alkalinity, calcium and acid neutralizing capacity first. This establishes baseline conditions and how much liming is needed.

• Increase pH gradually in increments. Don’t try to go from pH 5 to 7 all at once. Smaller doses over time are best.

• Use agricultural lime rather than quicklime or slaked lime products which change chemistry too rapidly.

• Lime periodically to maintain pH levels. Annual testing helps determine re-treatment needs.

• Factor in the waterbody’s natural buffering capacity. Waters with low alkalinity require more liming than those with high alkalinity.

• Consider natural limestone beds or riffles to add calcium over time rather than one large lime dose.

• Limit liming during salmon spawning periods and other critical life stages like egg development.

• Ensure limed water disperses fully before salmon fry emerge or are stocked. High turbidity from suspended lime can harm juvenile fish.

• Monitor effects on other aquatic species, plants and organisms. A balanced approach is ideal.

With proper planning and care, liming can be a useful tool for enhancing natural salmon waters. But as with any fisheries management practice, moderation is key.

Case Studies on Salmon Response to Liming

To further illustrate how salmonids respond to liming, here are two real-world examples:

Lake Superior

Lake Superior has dealt with impacts from mining and industrial emissions that increased acidity. pH levels declined to 5.0-5.5 in some areas. Research in the 1980s showed that lowered pH reduced survival of newly hatched lake trout by up to 95%.

Liming programs were implemented to restore pH levels. Finely ground limestone was spread by boat or dropped from aircraft. Target areas were pH 6.5-7.0.

After liming, lake trout hatching success rebounded significantly. The percentage of viable swim-up fry rose from 5% before liming to 60-100% after. Lake trout year class strength also increased dramatically. The results showed that strategic liming can successfully mitigate acidification effects on salmonids.

Kettle River, Minnesota

The Kettle River suffered from low pH around 4.7-5.2 and high aluminum levels that harmed the trout fishery. Liming was conducted in the headwaters flowing into Rice Lake.

The goal was to improve spawning habitat for rainbow trout and other fish. Limestone sand was spread over 20 miles of the river and tributaries in 1995.

Monitoring over the next decade revealed a substantial increase in trout abundance, especially juvenile fish. Average pH also improved to 6.0-7.0. While still acidic, the liming eased toxicity enough to benefit trout recruitment. Angler catch rates for stocked rainbow trout doubled after the liming.

The research shows that salmonids can benefit from careful liming to raise pH and calcium levels in overly acidic waters. When done properly, liming offers a way to increase salmonid survival and growth at sensitive early life stages. Liming also enhances reproduction by providing better spawning conditions for wild salmon and trout.

However, excessive liming can swing water chemistry too far in the other direction and damage fish communities. With appropriate liming guided by testing and monitoring, both salmon and anglers can reap rewards from improved habitat. Evaluating each scenario carefully is key to successful liming programs that enhance fisheries while avoiding unintended consequences.

Yes, lime juice is a great addition to fish dishes, offering a bright, tangy flavor and a way to “cook” the fish in ceviche. Lime juice complements seafood by adding a citrusy, refreshing flavor that can enhance the natural taste of fish.