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65-acre lake in Sudbury District, Ontario. The lake tops out around 60 ft. The depth data here comes from a transect sounding survey by the Ontario MNRF. Below is the species-by-species picture, pulled from the same data the map uses.
On the chart, Gem Lake draws 66 acres inside 1.5 miles of shoreline. At index 1.3 the outline is almost a bowl — read the depth changes, not the shoreline. About 18% of the surface sits shallower than 15 ft — that's the weed-and-bait zone. Call it 0.5 mi long by 0.3 mi wide at the broadest reach. The water lies in Sudbury District. Closest neighbour on DepthScout: Howry Lake, 1 mi west of here.
The spring pattern is a shallow one: lake trout in 10 to 40 ft. As the season builds they drop to 18 to 60 ft, wintering in 15 to 60 ft. Top water on the chart: Deep basin, a deep basin in the 60 ft range, prime in summer. Time it for early morning. Summer baits: a white tube jig (deep) or a magnum spoon on downrigger gets it done.
| Season | Depth | Best window | Start at | Go-to baits |
|---|---|---|---|---|
| Spring | 10 to 40 ft | dawn & dusk | Main-lake point (12 ft) | Casting spoon over shoals, Jerkbait (shallow) |
| Summer | 18 to 60 ft | dawn | Deep basin (60 ft) | White tube jig (deep), Magnum spoon on downrigger |
| Fall | 10 to 50 ft | dusk & dawn | Main-lake point (12 ft) | Heavy casting spoon, Jigging rap over reefs |
| Winter | 15 to 60 ft | dawn | Deep basin (60 ft) | White tube jig, Airplane jig |
Come spring, look for cisco (lake herring) tight to the bank in 10 to 40 ft. Expect a summer slide to 18 to 60 ft, then a winter hold in 20 to 60 ft. Start at Deep basin. It's a deep basin holding about 60 ft of water and rates prime come summer. Prime time lands in early morning. A vertical flutter spoon (small) or a drop-shot micro plastic is the honest summer answer here.
| Season | Depth | Best window | Start at | Go-to baits |
|---|---|---|---|---|
| Spring | 10 to 40 ft | dawn & dusk | Deep basin (60 ft) | Small silver spoon, Tiny swim jig (white) |
| Summer | 18 to 60 ft | dawn | Deep basin (60 ft) | Vertical flutter spoon (small), Drop-shot micro plastic |
| Fall | 5 to 25 ft | dusk & dawn | open water | Small casting spoon, Inline spinner (silver) |
| Winter | 20 to 60 ft | dawn | Deep basin (60 ft) | Small jigging spoon (glow/silver), Tungsten jig + minnow head |
Spring walleye on Gem Lake hold shallow, usually 4 to 15 ft. They move out to 15 to 35 ft in summer and finish the year down in 20 to 40 ft. Put Main-lake point first on the milk run — a point near 12 ft that grades prime for fall. The feeding windows run the evening and early morning. The summer box starts with a crawler harness on bottom bouncer or a deep crankbait (trolled).
| Season | Depth | Best window | Start at | Go-to baits |
|---|---|---|---|---|
| Spring | 4 to 15 ft | dusk & dawn | Main-lake point (12 ft) | 1/8 oz jig + minnow, Hair jig |
| Summer | 15 to 35 ft | dusk & dawn | Secondary point (18 ft) | Crawler harness on bottom bouncer, Deep crankbait (trolled) |
| Fall | 12 to 40 ft | dusk & night | Main-lake point (12 ft) | Jigging rap, Jig + big minnow |
| Winter | 20 to 40 ft | dusk & dawn | Break off the point (45 ft) | Jigging spoon + minnow head, Rattle bait |
Early season yellow perch use the shallows, holding in 3 to 12 ft. Expect a summer slide to 10 to 30 ft, then a winter hold in 15 to 35 ft. Put Shallow bay flat first on the milk run — a feeding flat near 2 ft that grades prime for spring. In summer the feeding windows fall in early morning. Tie on a drop-shot micro plastics or a small spoon tipped with worm and you're in the game.
| Season | Depth | Best window | Start at | Go-to baits |
|---|---|---|---|---|
| Spring | 3 to 12 ft | midday & dawn | Shallow bay flat (2 ft) | Small jig + curly tail, Perch-pattern micro crank |
| Summer | 10 to 30 ft | dawn | Back-bay flat (30 ft) | Drop-shot micro plastics, Small spoon tipped with worm |
| Fall | 12 to 35 ft | midday | Deep basin (60 ft) | Jigging spoon (small), Perch rig / spreader |
| Winter | 15 to 35 ft | midday & dawn | Back-bay flat (30 ft) | Tungsten jig + spikes, Rattle spoon (small) |
In spring, northern pike run shallow here, mostly 2 to 8 ft. Summer pushes them deeper, 8 to 20 ft, and winter fish settle into 5 to 15 ft. Shallow bay flat is the standout, a feeding flat at roughly 2 ft, rated prime for spring northern pike. Time it for early morning and the evening. You won't need more than a bucktail or a weedless spoon over cabbage most summer days.
| Season | Depth | Best window | Start at | Go-to baits |
|---|---|---|---|---|
| Spring | 2 to 8 ft | midday & dawn | Shallow bay flat (2 ft) | #5 inline spinner, Spoon (red/white) |
| Summer | 8 to 20 ft | dawn & dusk | Main-lake point (12 ft) | Bucktail, Weedless spoon over cabbage |
| Fall | 6 to 18 ft | midday & dawn | Main-lake point (12 ft) | Big rubber (Bull Dawg style), Husky-style jerkbait |
| Winter | 5 to 15 ft | midday | Main-lake point (12 ft) | Tip-ups, Large jigging spoon |
In spring, smallmouth bass run shallow here, mostly 3 to 12 ft. Summer pushes them deeper, 10 to 30 ft, and winter fish settle into 20 to 45 ft. Main-lake point is the standout, a point at roughly 12 ft, rated prime for fall smallmouth bass. Time it for early morning and the evening. You won't need more than a drop shot (goby/minnow) or a ned rig most summer days.
| Season | Depth | Best window | Start at | Go-to baits |
|---|---|---|---|---|
| Spring | 3 to 12 ft | dawn & dusk | Main-lake point (12 ft) | Ned rig, Tube jig |
| Summer | 10 to 30 ft | dawn & dusk | Main-lake point (12 ft) | Drop shot (goby/minnow), Ned rig |
| Fall | 8 to 25 ft | midday & dawn | Main-lake point (12 ft) | Jerkbait, Blade bait |
| Winter | 20 to 45 ft | midday | Break off the point (45 ft) | Blade bait, Hair jig |
Gem Lake also holds rock bass (5 to 20 ft in summer), bluegill (4 to 15 ft in summer), pumpkinseed (2 to 10 ft in summer), brown bullhead (3 to 12 ft in summer). Pick any of them on the map above for rated spots and bait picks.
Count 6 structure marks on this chart. The deepest, Deep basin, sits near 60 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 Gem Lake specifically, so confirm the current rules before you fish.
Check the official Ontario fishing regulations →
Gem Lake is about 60 ft (18 m) deep at its deepest point. The depth data here comes from a transect sounding survey by the Ontario MNRF.
Anglers target lake trout, cisco (lake herring), walleye, yellow perch, northern pike, smallmouth bass, rock bass, bluegill, pumpkinseed, brown bullhead on Gem Lake. This isn't a survey of the lake — none is on record for it — but an informed estimate from the species Ontario's MNRF recorded in the nearest surveyed lakes, filtered to this lake's depth and habitat.
Deep basin is the top-rated area: a deep basin in about 60 ft of water that rates prime for lake trout in summer. The map above holds the full rated-spot list for every species and season.
For lake trout, 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 Gem 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.
Howry Lake 1 mi · Bear Lake 2 mi · Fish Lake 2 mi · Gail Lake 3 mi · Little Mountain Lake 4 mi · Little Bear Lake 4 mi · Great Mountain Lake 4 mi · Walker Lake 4 mi · Nellie Lake 4 mi · Hanwood Lake 4 mi · Bodina Lake 5 mi · Threenarrows Lake 5 mi
See how Gem Lake stacks up: best smallmouth bass lakes in Ontario · best walleye lakes in Ontario · best northern pike lakes in Ontario · best bluegill lakes in Ontario
More water nearby: Sudbury District fishing maps (868 charts). Browse all Ontario fishing maps or see every water on DepthScout. Bathymetry credit: state fisheries survey programs. 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.