How Long Do Salmon Eggs Take To Hatch? A Look at the Salmon Life Cycle

As an avid angler and salmon enthusiast, I’m fascinated by the incredible lifecycle of these amazing fish One question I had was just how long do those tiny salmon eggs buried in gravel nests take until they hatch out into alevins? I decided to dig into the details of the salmon life cycle to find out.

During their lifetime, salmon make a long journey from the fresh water of rivers to the ocean and back again to spawn. The process starts with eggs being laid in the riverbed. These eggs will hatch into tiny alevins. But this process takes some time.

In this article, I’ll provide an overview of the full salmon life cycle and take a closer look at the incubation time for salmon eggs before they hatch. Read on to learn just how long you’ll be waiting to see those new baby salmon emerge from their gravel nests.

Overview of the Salmon Life Cycle

• From fall to winter, salmon lay their eggs in redds, which are large gravel nests in fresh water.

• The eggs are fertilized by adult male salmon and incubate over the winter, developing into embryos.

• As the spring comes on, the eggs hatch into alevins. The alevins stay in the gravel and eat their yolk sacs.

• Once the yolk is gone, the alevins emerge from gravel as fry and start feeding in the stream.

• After several months or years, the juvenile salmon undergo smoltification for the ocean.

• Salmon migrate downstream and spend 1-5 years maturing in the ocean before returning to freshwater streams to spawn.

• Adults spawn in their home streams, laying and fertilizing new eggs to restart the cycle.

• After spawning, the adult salmon die, providing nutrients to the stream ecosystem.

Now let’s take a closer look at those early stages of eggs and alevins to find out just how long salmon eggs take to hatch.

Salmon Egg Development and Hatching

Salmon eggs are laid in fall and winter, with actual spawning times varying by species and location. After the female excavates a gravel nest, called a redd, she deposits her eggs which are immediately fertilized by accompanying adult male salmon.

These fertilized eggs settle deep into the loose gravel of the redd. Oxygenated water flows through the gravel, allowing the salmon embryos to develop.

Salmon eggs are left on their own over the winter months, slowly progressing through various life stages within the protection of the gravel. Let’s look at approximately how long salmon eggs take to hatch for different salmon species:

• Chinook salmon: 10-14 weeks to hatch

• Coho salmon: 6-10 weeks to hatch

• Sockeye salmon: 6-20 weeks to hatch

• Chum salmon: 4-16 weeks to hatch

• Pink salmon: 4-16 weeks to hatch

As you can see, there is quite a range in the incubation time before salmon eggs hatch. What accounts for these differences?

What Influences Salmon Egg Hatching Time

Several environmental factors influence the time it takes for salmon eggs to fully develop and hatch in the wild:

• Water temperature – Warmer water speeds up embryonic development. Eggs hatch faster at 50°F vs 40°F.

• Dissolved oxygen – Eggs need continuous flow of oxygenated water – low levels slow hatching.

• Carbon dioxide – High carbon dioxide prolongs incubation time.

• Gravel size – Smaller gravel size reduces water flow and oxygen to eggs.

• Species – Each salmon species has a slightly different incubation duration.

• Location – Salmon populations from different rivers can show varied hatch times.

So cooler, faster flowing streams with ideal gravel size and water chemistry will result in faster salmon egg hatching compared to marginal habitat conditions.

In hatcheries, optimal conditions are provided to accelerate hatching time. But in the wild, incubation duration is also nature’s way of ensuring eggs hatch at the best time for survival based on local conditions.

From Egg Hatching to Emerging Fry

Once hatched, the salmon embryos remain in the gravel nest as alevins – still attached to their large yolk sac which provides nourishment. When the yolk is fully absorbed, they wiggle up through the gravel and emerge as free-swimming salmon fry to start feeding.

So you might ask, when do salmon alevins emerge from the gravel? Again, timing varies by species and conditions, but generally 1-2 months after hatching. Chinook alevins may emerge as soon as 4-6 weeks after hatching while Sockeye stay in the gravel 2-3 months.

These tiny baby salmon face extremely high mortality rates from predators, competitors, and environmental factors. But the survivors continue growing rapidly, preparing for the dangerous migration downstream to the ocean within their first year of life. Those that make it to sea and return to spawn complete the salmon life cycle.