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107-acre lake in Thunder Bay District, Ontario. The lake tops out around 77 ft. The contours are modeled from the water's real shoreline and maximum depth. Treat them as a rough guide, and never use them for navigation. Here is how the season plays out for each species, straight from the data behind the map.
Shamrock Lake maps at 107 acres behind 2.1 miles of shoreline. With a 1.5 development index there's bank structure worth casting at, in moderation. The shallow band under 15 ft claims about 16% of the surface on the model — that's where the groceries are. Tip to tip the water measures near 0.5 mi with a 0.5-mi widest point. It sits in Thunder Bay District. McKirdy Lake sits 1 mi southwest — the closest neighbouring chart.
Start shallow in spring: lake whitefish sit in 15 to 45 ft that time of year. Summer pushes them deeper, 23 to 77 ft, and winter fish settle into 25 to 70 ft. The spot to know is Deep basin, a deep basin in about 65 ft of water that rates prime for lake whitefish in summer. Warm-month bites cluster around early morning. Throw a blade bait vertical or a small jigging spoon until the fish tell you otherwise.
Depth note: when a documented seasonal range extends below this chart, the table shows the deepest mapped working water, not a verified holding depth.
| Season | Depth | Best window | Start at | Go-to baits |
|---|---|---|---|---|
| Spring | 15 to 45 ft | midday & dawn | Break off the point (35 ft) | Small jig + waxworm, Blade bait (small) |
| Summer | 23 to 77 ft chart-limited; documented 40 to 90 ft | dawn | Deep basin (65 ft) | Blade bait vertical, Small jigging spoon |
| Fall | 8 to 30 ft | dusk | Main-lake point (19 ft) | Small spoon (gold), Jig + plastic larva |
| Winter | 25 to 70 ft | midday & dawn | Deep basin (65 ft) | Jigging spoon + bead chain, Tungsten jig + waxie |
The spring pattern is a shallow one: yellow perch in 3 to 12 ft. Midsummer fish sit out in 10 to 30 ft before dropping to 15 to 35 ft for winter. The spot to know is Break off the point, a drop-off in about 35 ft of water that rates prime for yellow perch in fall. Plan around early morning in the warm months. Summer baits: a drop-shot micro plastics or a small spoon tipped with worm gets it done.
| Season | Depth | Best window | Start at | Go-to baits |
|---|---|---|---|---|
| Spring | 3 to 12 ft | midday & dawn | Shallow bay flat (6 ft) | Small jig + curly tail, Perch-pattern micro crank |
| Summer | 10 to 30 ft | dawn | Break off the point (35 ft) | Drop-shot micro plastics, Small spoon tipped with worm |
| Fall | 12 to 35 ft | midday | Break off the point (35 ft) | Jigging spoon (small), Perch rig / spreader |
| Winter | 15 to 35 ft | midday & dawn | Break off the point (35 ft) | Tungsten jig + spikes, Rattle spoon (small) |
When the water first warms, northern pike slide up into 2 to 8 ft. Summer is an 8 to 20 ft game here, winter a 5 to 15 ft one. Start at Shallow bay flat. It's a feeding flat holding about 6 ft of water and rates prime come spring. The feeding windows run early morning and the evening. Keep a bucktail or a weedless spoon over cabbage rigged through the warm months.
| Season | Depth | Best window | Start at | Go-to baits |
|---|---|---|---|---|
| Spring | 2 to 8 ft | midday & dawn | Shallow bay flat (6 ft) | #5 inline spinner, Spoon (red/white) |
| Summer | 8 to 20 ft | dawn & dusk | Main-lake point (19 ft) | Bucktail, Weedless spoon over cabbage |
| Fall | 6 to 18 ft | midday & dawn | Shallow bay flat (6 ft) | Big rubber (Bull Dawg style), Husky-style jerkbait |
| Winter | 5 to 15 ft | midday | Shallow bay flat (6 ft) | Tip-ups, Large jigging spoon |
The chart marks 6 structure features on Shamrock Lake; the deepest is Deep basin at about 65 ft.
Season dates, license requirements, and size and bag limits for Ontario waters are set by the Ontario fishing regulations (FMZ summary) — and special regulations can apply to Shamrock Lake specifically, so confirm the current rules before you fish.
Check the official Ontario fishing regulations →
Shamrock Lake is about 77 ft (23 m) deep at its deepest point. The contours here are modeled from the water's real shape and maximum depth, so treat them as a rough guide.
Anglers target lake whitefish, yellow perch, northern pike on Shamrock Lake.
Deep basin is the top-rated area: a deep basin in about 65 ft of water that rates prime for lake whitefish in summer. Scroll up to the map for the complete spot list by species and season.
For lake whitefish, the summer bite is best in early morning. Each species page section below lists the seasonal windows, and the map shows a live NOW badge when you're inside one.
Fishing on Shamrock Lake is regulated by the Ontario fishing regulations (FMZ summary). Check the official Ontario regulations for current license requirements, season dates, and size and bag limits — special regulations can apply to this specific water.
McKirdy Lake 1 mi · Keemle Lake 1 mi · Gorge Lake 5 mi · Cosgrave Lake 9 mi · Postagoni Lake 10 mi · Forgan Lake 10 mi · Cox Lake 10 mi · Kilgour Lake 11 mi · Georgia Lake 12 mi · Oskawe Lake 12 mi · Lake Jean 14 mi · Parland Lake 14 mi
See how Shamrock Lake stacks up: best northern pike lakes in Ontario · best yellow perch lakes in Ontario · best lake whitefish lakes in Ontario
More water nearby: Thunder Bay District fishing maps (662 charts). Browse all Ontario fishing maps. See every water on DepthScout. How we build these maps. Fish here with a sonar unit that logs? Send us your depth data and we'll improve this chart, credited to you. For fishing guidance only, never navigation.