When do Salmon run in Lake Ontario?

South Shore Salmon Slowly Showing?

Discussing factors influencing the run, and fishing opportunities on the south shore.

Every year, Lake Ontario Chinook salmon begin scouting shallow water around river mouths as they prepare for the fall run. On the north shore of Lake Ontario, this process usually starts at the beginning of August, but can be expedited by big rains as most natural fish look to run the rivers earlier than stocked fish.

Anglers fishing in Niagara typically see some salmon entering the whirlpool in late-August, but don’t experience big numbers of fish running until early or mid-September. Why so much later?

Understanding the dynamics of chinook salmon migration on Lake Ontario is complex, but breaking it down to understand key factors will help immensely to understand where the run is at.

Fisheries Management Strategies

After studying the history of salmon in the great lakes for a few years at university, my already huge interest in salmon grew, and I became the pen project lead for Port Dalhousie through the St. Catharines Game and Fish Association. 

For those not familiar, a “pen-project” is where chinook salmon fry are raised in net-pens and then released into the wild after being fed and monitored for several weeks. Research has shown that salmon fry raised in pens as opposed to being dumped straight into the Lake have a two to one survival rate, which is a big deal for biologists managing the ecosystem.

The task of fisheries management is to manage fish populations for the environment, and to support sportfishing. Zones have been established in the Lake, and specific objectives are outlined for each zone, with environmental conditions taken into account.

On the south shore (classified the western end of Lake Ontario), it is believed that very little to no natural reproduction occurs because of unsuitable stream habitat. For that reason, this end of the lake receives the largest share of stocked fish on the lake, with the goal being to support the fall fishery by supplying fish that return.

Sites such as Port Dalhousie with a proven track record of imprinting success (returning fish) are valuable in the lake-wide management strategy, because they ensure the investment put into the west end, returns to the west end.

Genetics

Genetics are an important caveat to the fisheries management strategy, and understanding the run on the south shore because they’re critical to what makes up the characteristics of fish that are stocked in the first place.

Stocked salmon fry are the ancestors of fish that run up the Credit river and the Ganaraska River and are created by volunteer-collected eggs and milt. The ministry has picked these sites because they draw fish from different areas of the lake, and they both support natural reproduction.

It is widely believed that “natural” salmon that are products of parent fish with lineage of natural reproduction, tend to mature and consequently run earlier – and I am a firm believer of that.

This tends to explain why north shore tributaries see earlier staging salmon and migration, while the south shore is significantly later, due to their “stocked” genetics.

Pen Project Success

Of course, the ability of a pen project to produce healthy fry before release is a critical first step to creating a return population after 2-3 years. If bad springtime weather prevents fry from growing during the rearing period, they are more susceptible to predators upon release.

Wind

Just like at any other time of the year, wind effects where fish set up when it comes time to stage. Water infront of Niagara’s ports (Grimsby, Jordan, Dalhousie, Weller, Niagara River), is largely shallower and warmer than the lake’s north shore, so pockets of warm water can delay the run or make fish lethargic during the staging period.

Other factors

Finally, the factors discussed in this post are not gospel, and must be taken with a grain of salt. I don’t think we will ever fully understand the behavior of the King salmon, but they’re important nonetheless.

Feeling the jolt of the rod in pitch dark as an angry king crushes your glow spoon is arguably the best bite you will feel as a freshwater angler.