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4,258-acre lake near Québec. The lake tops out around 70 ft. The depth chart is built from real state fisheries GPS surveys, so the humps, channels and drop-offs you see are measured, not guessed. The rest of this page walks each species through its year, using the map's own scoring.
Traced from the shoreline, Grand lac Bostonnais runs 4,258 acres with 28.9 miles of edge. A development index of 3.2 means a maze of bays and points: far more casting targets than a round bowl of the same size. 53% of the surface is littoral (under ~15 ft) — cover, weeds and forage water. Call it 7.9 mi long by 4.7 mi wide at the broadest reach. You'll find it in La Tuque. For a second option, Lac Écarté lies 7 mi northwest.
Carte de pêche interactive gratuite — Grand lac Bostonnais, Québec : courbes de profondeur issues de relevés bathymétriques réels jusqu'à 21 m (70 pi), et les meilleurs sites pour omble de fontaine, touladi, grand corégone et plus. Les profondeurs proviennent de la Géobase des bathymétries de lac du Québec (MELCCFP) lorsque disponibles.
In spring, brook trout run shallow here, mostly 2 to 15 ft. Summer pushes them deeper, 10 to 30 ft, and winter fish settle into 3 to 20 ft. Sharp break is the standout, a drop-off at roughly 11 ft, rated prime for summer brook trout. Time it for early morning and the evening. You won't need more than a small spoon fished deep or a trolled lake-clear wobbler + worm most summer days.
| Saison | Profondeur | Meilleure fenêtre | Commencer à | Leurres |
|---|---|---|---|---|
| Printemps | 2 to 15 ft | dawn & dusk | Main-lake point (5 ft) | Small inline spinner (gold), Tiny spoon |
| Été | 10 to 30 ft | dawn & dusk | Sharp break (11 ft) | Small spoon fished deep, Trolled lake-clear wobbler + worm |
| Automne | 2 to 15 ft | midday & dawn | Main-lake point (5 ft) | Small spoon (orange), Spinner |
| Hiver | 3 to 20 ft | dawn | Break off the point (7 ft) | Small jigging spoon, Tungsten jig + plastic |
Spring puts lake trout in skinny water — 10 to 40 ft is the zone. Warm water sends them out to 21 to 70 ft; cold water stacks them in 18 to 70 ft. Deep basin is the standout, a deep basin at roughly 69 ft, rated prime for summer lake trout. Plan around early morning in the warm months. A white tube jig (deep) or a magnum spoon on downrigger covers the summer program.
| Saison | Profondeur | Meilleure fenêtre | Commencer à | Leurres |
|---|---|---|---|---|
| Printemps | 10 to 40 ft | dawn & dusk | Sharp break (11 ft) | Casting spoon over shoals, Jerkbait (shallow) |
| Été | 21 to 70 ft | dawn | Deep basin (69 ft) | White tube jig (deep), Magnum spoon on downrigger |
| Automne | 10 to 50 ft | dusk & dawn | Rock reef (6 ft) | Heavy casting spoon, Jigging rap over reefs |
| Hiver | 18 to 70 ft | dawn | Deep basin (69 ft) | White tube jig, Airplane jig |
Early season lake whitefish use the shallows, holding in 15 to 45 ft. Summer is a 21 to 70 ft game here, winter a 25 to 70 ft one. The chart's best answer is Deep basin — deep basin, 69 ft, prime for summer. Best bite is early morning. Tie on a blade bait vertical or a small jigging spoon and you're in the game.
| Saison | Profondeur | Meilleure fenêtre | Commencer à | Leurres |
|---|---|---|---|---|
| Printemps | 15 to 45 ft | midday & dawn | Shallow feeding flat (17 ft) | Small jig + waxworm, Blade bait (small) |
| Été | 21 to 70 ft | dawn | Deep basin (69 ft) | Blade bait vertical, Small jigging spoon |
| Automne | 8 to 30 ft | dusk | Rock reef (6 ft) | Small spoon (gold), Jig + plastic larva |
| Hiver | 25 to 70 ft | midday & dawn | Deep basin (69 ft) | Jigging spoon + bead chain, Tungsten jig + waxie |
Early season cisco (lake herring) use the shallows, holding in 10 to 40 ft. Summer is a 21 to 70 ft game here, winter a 20 to 60 ft one. The chart's best answer is Deep basin — deep basin, 69 ft, prime for summer. Best bite is early morning. Tie on a vertical flutter spoon (small) or a drop-shot micro plastic and you're in the game.
| Saison | Profondeur | Meilleure fenêtre | Commencer à | Leurres |
|---|---|---|---|---|
| Printemps | 10 to 40 ft | dawn & dusk | Sharp break (11 ft) | Small silver spoon, Tiny swim jig (white) |
| Été | 21 to 70 ft | dawn | Deep basin (69 ft) | Vertical flutter spoon (small), Drop-shot micro plastic |
| Automne | 5 to 25 ft | dusk & dawn | Rock reef (6 ft) | Small casting spoon, Inline spinner (silver) |
| Hiver | 20 to 60 ft | dawn | Deep basin (69 ft) | Small jigging spoon (glow/silver), Tungsten jig + minnow head |
Come spring, look for walleye tight to the bank in 4 to 15 ft. Expect a summer slide to 15 to 35 ft, then a winter hold in 20 to 40 ft. Start at Sharp break. It's a drop-off holding about 11 ft of water and rates prime come fall. Prime time lands in the evening and early morning. A crawler harness on bottom bouncer or a deep crankbait (trolled) is the honest summer answer here.
| Saison | Profondeur | Meilleure fenêtre | Commencer à | Leurres |
|---|---|---|---|---|
| Printemps | 4 to 15 ft | dusk & dawn | Rock reef (6 ft) | 1/8 oz jig + minnow, Hair jig |
| Été | 15 to 35 ft | dusk & dawn | Sharp break (11 ft) | Crawler harness on bottom bouncer, Deep crankbait (trolled) |
| Automne | 12 to 40 ft | dusk & night | Sharp break (11 ft) | Jigging rap, Jig + big minnow |
| Hiver | 20 to 40 ft | dusk & dawn | Deep basin (69 ft) | Jigging spoon + minnow head, Rattle bait |
Come spring, look for yellow perch tight to the bank in 3 to 12 ft. They move out to 10 to 30 ft in summer and finish the year down in 15 to 35 ft. If you only fish one area, make it Shallow bay flat: a weed flat around 4 ft that scores prime in spring. Best bite is early morning. A drop-shot micro plastics or a small spoon tipped with worm is the honest summer answer here.
| Saison | Profondeur | Meilleure fenêtre | Commencer à | Leurres |
|---|---|---|---|---|
| Printemps | 3 to 12 ft | midday & dawn | Shallow bay flat (4 ft) | Small jig + curly tail, Perch-pattern micro crank |
| Été | 10 to 30 ft | dawn | Sharp break (11 ft) | Drop-shot micro plastics, Small spoon tipped with worm |
| Automne | 12 to 35 ft | midday | Sharp break (11 ft) | Jigging spoon (small), Perch rig / spreader |
| Hiver | 15 to 35 ft | midday & dawn | Shallow feeding flat (17 ft) | Tungsten jig + spikes, Rattle spoon (small) |
Grand lac Bostonnais also holds burbot (21 to 70 ft in summer). Pick any of them on the map above for rated spots and bait picks.
12 pieces of structure are mapped here — Deep basin, around 69 ft, is the deepest of them.
Season dates, license requirements, and size and bag limits for Québec waters are set by the Québec sport fishing rules (MELCCFP) — and special regulations can apply to Grand lac Bostonnais specifically, so confirm the current rules before you fish.
Check the official Québec fishing regulations →
Grand lac Bostonnais is about 70 ft (21 m) deep at its deepest point. The depth chart here comes from real state fisheries GPS surveys, so the contours reflect measured depths.
Grand lac Bostonnais atteint environ 21 m (70 pi) à son point le plus profond. Les profondeurs proviennent de relevés bathymétriques réels.
Anglers target brook trout, lake trout, lake whitefish, cisco (lake herring), walleye, yellow perch, burbot on Grand lac Bostonnais. This species list is an informed estimate from Québec's provincial fish-range maps (bounded by each lake's depth and habitat), not a per-lake fish survey — Québec doesn't publish per-lake species records.
Deep basin is the top-rated area: a deep basin in about 69 ft of water that rates prime for lake trout in summer. Every other rated spot, per species and season, is on the map above.
For brook trout, the summer bite is best in early morning and the evening. Each species page section below lists the seasonal windows, and the map shows a live NOW badge when you're inside one.
Fishing on Grand lac Bostonnais is regulated by the Québec sport fishing rules (MELCCFP). Check the official Québec regulations for current license requirements, season dates, and size and bag limits — special regulations can apply to this specific water.
Lac Écarté 7 mi · Lac Magny 15 mi · Lac aux Cailloux 15 mi · Lac aux Montagnais 16 mi · Lac Étoile 17 mi · Lac Berthiaume 17 mi · Lac Durocher 18 mi · Lac Prinzèles 19 mi · Lac Métascouac 19 mi · Lac des Commissaires 19 mi · Lac Saint-Henri 19 mi · Lac Goulet 20 mi
See how Grand lac Bostonnais stacks up: best walleye lakes in Québec · best yellow perch lakes in Québec · best lake trout lakes in Québec · best brook trout lakes in Québec
More water nearby: La Tuque fishing maps (5 charts). Browse all Québec 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.