Frontenac County, Ontario

Big Gull Lake

Twenty-five square kilometers of cool water across North and Central Frontenac, with 154 islands and 168 kilometers of shoreline, charted to 24.4 meters in the 1958 survey. Seventy-three walleye spawning areas are mapped.

Surface: 24.7 km²
Shoreline: 168 km117 mainland + 51 islands
Islands: 154
Charted depth: 24.4 m
Depth contours: 66

All figures are derived from Ontario’s survey records.

Where Big Gull Lake is

Big Gull Lake lies in the County of Frontenac, with shoreline in the Township of North Frontenac and the Township of Central Frontenac.

How deep is Big Gull Lake?

The deepest mapped contour on Big Gull Lake is 24.4 meters, and the water within that boundary descends even farther. Ontario’s bathymetry record holds 66 depth contours for Big Gull Lake.

The deepest charted contour on Big Gull Lake, 24.4 meters, from the 1958 survey. The circle marks the centre of that contour, and the water within it is deeper. The survey’s sixty-six depth contours are drawn where the province published them, and along the outline where the survey placed them beyond it. Outline from the Ontario Hydro Network. Each contour is labelled with its depth in meters; zoom in where they run close.

Surveyed Depths

Ontario has surveyed the depths of several thousand of its lakes over more than half a century. Later surveys were conducted by boat with satellite positioning and produced hundreds of thousands of soundings per lake. Earlier surveys were charted by running transects across the water and drawing depth contours by hand.

Water quality

Ontario’s Lake Partner Program is a volunteer monitoring network. Participants collect a water sample each spring for phosphorus analysis and measure water clarity through the summer with a Secchi disk.

Phosphorus is the nutrient that controls how much algae a lake can grow. A lake with little phosphorus stays clear and supports cold-water fish such as lake trout. As phosphorus rises, algae increase, the water clouds, and oxygen in the deep water falls as the algae decay. The province classifies each monitoring site by its spring phosphorus. Below 10 micrograms per litre is oligotrophic: clear water and low algae. From 10 to 20 is mesotrophic: moderately productive water, with more algae and weed growth than an oligotrophic lake but rarely a bloom. Above 20 is eutrophic: nutrient-rich water, prone to algal blooms and low oxygen at depth.

A Secchi disk is a 20 centimeter white or black-and-white plate lowered on a marked line until it disappears from view. The depth at which it vanishes is the Secchi depth, a direct measure of water clarity. Clearer water gives a deeper reading.

Big Gull Lake has 5 Lake Partner monitoring sites. Four have reported phosphorus for the three or more years the province requires before a status is assigned. Two of those sites are classified oligotrophic and two mesotrophic.

Lake Partner sites on Big Gull Lake with a quotable phosphorus record
Site	Location	Years	Last sampled	Classification
373/3	Pinnacle Point	24	2025	oligotrophic
373/5	W Bay, deep spot	23	2025	mesotrophic
373/4	Tan Bark Bay	22	2025	oligotrophic
373/1	E Long Is-NofNarrows	20	2025	mesotrophic

The longest record is held by site 373/3 at Pinnacle Point, sampled over 24 springs to 2025. Its long-term mean phosphorus concentration is 8.92 micrograms per litre, within the oligotrophic band, which extends to 10. The site’s 232 clarity readings give a median Secchi depth of 4.3 meters.

Median Secchi depth by year at site 373/3, surface at the top. The thin line through each bar spans the shallowest and deepest reading that year, and the row beneath the years gives the number of readings. Years without readings are blank.

Fish in Big Gull Lake

Ontario’s aquatic resource records name 24 fish species in Big Gull Lake. The province classes the lake as cool water. The record took effect on 1 November 2018, and it compiles what field biologists had reported by then. The province’s other records for the lake name one further species, lake trout. It appears in the records below.

Thirteen of the 25 species in the province’s records

Lake Whitefishtrout and whitefish
Ciscotrout and whitefish
Northern Pikepike
Muskellungepike
Walleyeperch
Yellow Perchperch
Smallmouth Basssunfish
Largemouth Basssunfish
Rock Basssunfish
Pumpkinseedsunfish
Bluegillsunfish
Burbotcod
Brown Bullheadcatfish

The other twelve species in the province’s records
Family	Species
Trout and whitefish	lake trout
Perch	logperch
Sucker	white sucker
Minnow	blacknose shiner, bluntnose minnow, carps and minnows, emerald shiner, fathead minnow, golden shiner, mimic shiner, spottail shiner
Other	pumpkinseed x bluegill

Spawning areas

Ontario maps 73 fish spawning records within the Big Gull Lake outline: 73 walleye spawning areas covering 3.99 hectares.

By number of records

By area mapped

Walleye73 areas4.0 ha

Spawning records mapped by the province within the Big Gull Lake outline. A record under 100 square meters is drawn as a dot; a spawning area is drawn as the outline mapped. One colour per species, the same as the bars and the list above.

The federal Fisheries Act prohibits the harmful alteration, disruption or destruction of fish habitat without an authorization, so a dock, dredging, infill or shoreline work at a mapped spawning area is reviewed on that basis.

Stocking history

Ontario’s stocking records for Big Gull Lake run from 1946 to 1989 and hold 68 releases. Walleye account for most of the fish: 8,145,000 released in ten of the years between 1946 and 1989. The last recorded release was 345,000 walleye frys in 1989.

Fish released into Big Gull Lake, 1946 to 1989
Species	Years	Years with a release	Fish released
Walleye	1946 to 1989	10	8,145,000
Muskellunge	1954 to 1962	7	153,000
Smallmouth Bass	1946 to 1956	11	63,050
Largemouth Bass	1949 to 1959	9	42,648
Lake Trout	1946 to 1953	3	11,250

The province’s current stocking programme, recorded from 2016, lists no release into Big Gull Lake.

Eating the fish

The 2025 Guide to Eating Ontario Fish carries consumption advice for ten species taken from Big Gull Lake, tested for contaminants at a sampling location in Barrie, Clarendon & Kennebec Twps., Frontenac Co. Each figure below is the most meals a month the guide advises for a fish of that length. The advice falls as the fish gets longer, because mercury accumulates over a fish’s life. A zero means the guide advises no meals of that fish at that size.

General population adultsSensitive population children under fifteen, women who are or may become pregnant

Lake Whitefish Mercury, PCB
Length, cm	35 to 40	40 to 45	45 to 50	50 to 55	55 to 60	60 to 65	65 to 70
General population	16	16	16	12	12	8	4
Sensitive population	8	8	8	8	8	8	4

Cisco Mercury
Length, cm	25 to 30	30 to 35	35 to 40	40 to 45
General population	32	16	16	12
Sensitive population	12	8	4	4

Walleye Mercury
Length, cm	15 to 20	20 to 25	25 to 30	30 to 35	35 to 40	40 to 45	45 to 50	50 to 55	55 to 60	60 to 65
General population	32	16	16	16	12	8	8	8	4	4
Sensitive population	12	8	8	4	4	4	0	0	0	0

Northern Pike Mercury
Length, cm	35 to 40	40 to 45	45 to 50	50 to 55	55 to 60	60 to 65	65 to 70	70 to 75	over 75
General population	32	32	16	16	16	12	12	8	4
Sensitive population	16	12	8	8	4	4	4	4	0

Smallmouth Bass Mercury
Length, cm	15 to 20	20 to 25	25 to 30	30 to 35	35 to 40	40 to 45	45 to 50
General population	16	16	12	8	4	2	2
Sensitive population	8	8	4	0	0	0	0

Largemouth Bass Mercury
Length, cm	25 to 30	30 to 35	35 to 40	40 to 45	45 to 50
General population	16	12	8	8	4
Sensitive population	8	4	4	0	0

Yellow Perch Mercury
Length, cm	20 to 25	25 to 30	30 to 35
General population	16	16	12
Sensitive population	8	4	4

Burbot no contaminant listed
Length, cm	45 to 50
General population	32
Sensitive population	12

White Sucker no contaminant listed
Length, cm	40 to 45	45 to 50
General population	32	32
Sensitive population	16	16

Bluegill Mercury
Length, cm	15 to 20	20 to 25
General population	32	16
Sensitive population	16	8

Fisheries Management Zone 18

Big Gull Lake lies in Fisheries Management Zone 18. Ontario sets its fishing seasons and catch limits by zone.

Zone 18 seasons and limits, 2026
Species	Open season	Sport licence	Conservation licence
Brook Trout	Open all year	5	2
Brown Trout	Open all year	5	2
Channel Catfish	Open all year	12	6
Crappie	Open all year	30	10
Lake Trout	4th Sat. in May – Sept. 8	2	1
Lake Whitefish	Open all year	12	6
Largemouth and Smallmouth Bass or any combination	3rd Sat. in June – Dec. 15	6	2
Muskellunge	1st Sat. in June – Dec. 15	1, must be greater than 91 cm (36 in.)	0
Northern Pike	Jan. 1 – Mar. 31 & 2nd Sat. in May – Dec. 31	6	2
Pacific Salmon	Open all year	5	2
Rainbow Trout	Open all year	5	2
Splake	Open all year	5	2
Sunfish	Open all year	300, only 30 may be greater than 18 cm (7.1 in.)	15
Walleye and Sauger or any combination	Jan. 1 – Mar. 1 & 2nd Sat. in May – Dec. 31	4, must be between 40 – 50 cm (15.7 – 19.7 in.)	2, must be between 40 – 50 cm (15.7 – 19.7 in.)
Yellow Perch	Open all year	50	25

The figures are the number of fish an angler may catch and keep in a day and have in possession, under a sport fishing licence and under a conservation licence. The rows are the whole zone’s, and they apply to every lake in it. No waterbody exception names Big Gull Lake.

Big Gull Lake Ice Fishing

An ice hut on Big Gull Lake must be removed by March 15. Big Gull Lake lies in fisheries management zone 18, one of the twenty zones Ontario sets its fishing rules by, and one removal date applies across the whole zone.

An ice hut must also be removed before the ice breaks up, whether or not that date has passed. The deadline clears huts from the ice ahead of the thaw and does not close the fishing season.

Registration is required in zone 18 for an ice hut built of anything other than fabric, and for a fabric tent covering seven square meters or more. Registration is free, and the number is displayed on the outside of the hut.

Ice conditions

No public record reports the thickness or the condition of the ice on Big Gull Lake on any given day. Ontario publishes ice safety guidance for anyone going out on the ice, at ontario.ca.

Islands and names

Big Gull Lake contains 154 islands in the Ontario Hydro Network’s outline, three of them over 10 hectares and 92 under a tenth of a hectare. Seven of them lie inside wetlands mapped in the province’s Wetland With Significance dataset. Long Island, at 89 hectares, is larger than the next ten together, which cover 64.

The ten largest islands outside a mapped wetland, numbered to the table. Areas are measured on the province’s outline.

The ten largest islands outside a mapped wetland
	Island	Hectares
1	Long Island	88.9
2	unnamed	15.9
3	Green Island	13.0
4	Big Boundary Island	8.1
5	unnamed	7.2
6	unnamed	5.0
7	unnamed	4.7
8	unnamed	4.2
9	Bear Island	2.3
10	Upper Sister Island	1.7

Official names

Ontario’s geographic names register lists 24 official names on the water and its islands: 19 islands and three bays.

Bays 3

Earls Bay
East Bay
Watkin Bay

Nearby lakes

Kashwakamak Lake7 km away
Kennebec Lake12 km away
Crotch Lake14 km away
Buckshot Lake21 km away

All lakes

Questions about Big Gull Lake

How deep is Big Gull Lake?
Its deepest charted contour is 24.4 meters, and the water within it is deeper.
How big is Big Gull Lake?
Its surface covers 24.7 square kilometers and it holds 154 islands. Of its 168 kilometers of shoreline, 117 kilometers is the mainland shore and 51 kilometers is the shore of the islands.
What fish are in Big Gull Lake?
Ontario’s aquatic resource records name 24 species, among them walleye, smallmouth bass, largemouth bass, northern pike, muskellunge and lake whitefish. The lake’s spawning, consumption and stocking records also name lake trout.

A print of Big Gull Lake

Big Gull Lake has not yet been drawn as a print. The lakes drawn so far are on the lake maps page, and a print of Big Gull Lake can be requested by email; whether it can be drawn is confirmed before any payment.

Ask about a Big Gull Lake print

Looking at a property on Big Gull Lake?

Depth and water quality are two records out of many. Our Rural & Cottage Buyer’s Report gathers what the public record holds about one specific address: shore road allowance, road access, wells, flood mapping, Crown land, wetlands and more, read and checked by a person before it is sent.

See what is in the report

What these figures do and do not say

Depth: A depth reading is the distance from the water surface on the day of survey to the lake bottom. Lake levels vary through the season and between years. The depth figure above is the deepest contour charted and is a minimum; the depth within it was not recorded. The figures for Big Gull Lake are read from the province’s bathymetry records within the Ontario Hydro Network’s outline of the lake: the deepest figure is the deepest record inside that outline, and the count is every record inside it.
Shoreline and surface: The shoreline figure is the length of the mainland shore and of every island shore added together, measured on the Ontario Hydro Network’s outline of the lake. The surface figure is the area of water inside that outline, less the area of its islands. The provincial outline is mapped to within a few meters of the shore, and a shoreline measured from a coarser map comes out shorter, which is why a figure published elsewhere is often lower.
Survey coverage: Not every survey covered every arm of a lake, and the province’s index does not always record where a survey ended.
Water quality: Each figure belongs to a single monitoring site and not to the lake as a whole. A bay receiving a creek can read differently from open water half a kilometer away. Sites are matched to Big Gull Lake by name in the province’s records.
Nearby lakes: Distances are measured between lake centres.
Islands and names: Islands are counted and measured on the Ontario Hydro Network outline; names are the register’s, placed by its own coordinate. The register names islands the outline draws as part of a larger one, and the outline holds islands the register has not named, so the two counts differ. The outline carries some lakes across marsh, so a gap in the marsh is drawn as land, and every such gap is included in the island count. Where the register has not named one and it lies mostly inside a wetland in the province’s Wetland With Significance dataset, the page names the wetland and the table of largest islands leaves it out. Wetland boundaries are mapped at their own scale and can cover a small island whole.
Depth contours: Each contour is drawn where the survey placed it, at the survey’s own positional accuracy. The survey carries its own shoreline, which differs from the Ontario Hydro Network’s outline, so a contour near the shore can run to or past the outline. Such a stretch is drawn along the outline, as a drawing convention, and is not the survey’s line there. The contour count in the stat band is the province’s, and it includes the survey’s own shoreline contour, one ring around the mainland and one around each charted island, which the map leaves off; the map’s small print gives the split.
Location: Municipal boundaries are read from the province’s records as published and can lag a boundary change.
Fish: Ontario’s fish records are compilations of existing knowledge from field biologists and do not represent exhaustive inventories. A species that is not listed was not ruled out. The species list carries one date for the whole record and none for any species.
Spawning areas: A spawning area is drawn where the province mapped it, at the province’s stated accuracy, and the record says nothing about how many fish use it in a given year. A nest record is one nest seen on one day; a count of nests is not a count of fish, and a count of records is not a comparison between species. Whether a given piece of work needs an authorization is a determination made by Fisheries and Oceans Canada on the work itself.
Stocking: A stocking record is a release on a date. It says nothing about how many fish survived or about the population in the lake today.
Eating advice: The guide’s advice is for fish taken from the lake at the tested location and applies to the size classes tested. The province’s guide is the authority and is updated each year.
Fishing rules: Seasons and limits are the zone’s, for the year of the dataset the page was built from, and a licence’s own conditions and any waterbody exception apply over them. The province’s regulations summary is the authority.
Ice hut rules: Removal dates and registration rules are set by fisheries management zone and change from time to time. The dates here were read from the province in September 2026. The province’s own fishing regulations are the authority.

Where these figures come from

Depth, shoreline, islands and named places: Ontario Ministry of Natural Resources bathymetry and the Ontario Hydro Network, © King’s Printer for Ontario, Open Government Licence – Ontario.
Phosphorus and water clarity: Ontario Lake Partner Program, Ministry of the Environment, Conservation and Parks, Open Government Licence – Ontario. Extract built 2026-08-09.
Aerial photography: Geospatial Ontario imagery, Open Government Licence – Ontario, released collections only.
Official names: Geographic Names Ontario, Ministry of Natural Resources, Open Government Licence – Ontario. Marinas: Overture Maps Foundation places data, CDLA-Permissive 2.0.
Lake outline and municipal boundaries: Ontario Hydro Network and Ontario municipal boundary records, Ministry of Natural Resources, Open Government Licence – Ontario.
Fish species and thermal regime: Ontario Aquatic Resource Area records. Spawning areas: Ontario Fish Activity Area records. Both Ministry of Natural Resources, Open Government Licence – Ontario.
Stocking: Historical Fish Stocking Data and Fish Stocking Data for Recreational Purposes, Ministry of Natural Resources, Open Government Licence – Ontario.
Consumption advice: Guide to Eating Ontario Fish advisory database, 2025 edition, Ministry of the Environment, Conservation and Parks, Open Government Licence – Ontario.
Seasons and limits: Ontario recreational fishing regulations data, Ministry of Natural Resources, Open Government Licence – Ontario.
Fish plates: Duane Raver, U.S. Fish and Wildlife Service; Ellen Edmonson and Hugh Chrisp, New York State Conservation Department; Timothy Knepp, U.S. Fish and Wildlife Service; U.S. Fish and Wildlife Service. All public domain.
Ice hut removal dates and registration: Ontario fishing regulations, read September 2026.