Importance of Protecting Lake Trout

Importance of Protecting Lake Trout

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•250,000 lakes in Ontario•1% of these contain lake trout•Central/eastern Ontario has >1/3 of lakes• Provincial responsibility to preserve Why Protect Lake Trout Waters?

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Why Protect Lake Trout Waters?  Represents 20-25% of world’s supply  Largest area of lake trout waters  Ontario has greatest responsibility in world

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Lake Trout requirements =

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Phosphorous Affects Oxygen =

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Lake Trout Lake Protection  Province is committed to protecting fish habitat  Cooperative effort with municipalities Provincial Policy Statement Official Plan is the planning tool

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Why Protect Lake Trout?  Native only to North America  Native stocks found on Canadian Shield  Isolated 10,000 years ago Lake trout stocks genetical y dissimilar  Once lost, no way to replace it  Keystone species, indicator of ecosystem health

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Lake Trout Life History  Need deep, wel oxygenated, cold water lake environments to thrive – Late summer critical  Slow growing, late maturing, low productive potential

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Lake Trout vs Wal eye lake trout walleye • Fal spawn, 3-5 • Spring spawn, 12- month incubation 18 day incubation • Females mature @ • Females mature @ age-6 to 7 age-3 to 4 • Produce 900 -2600 • Produce 6000 – eggs per kg 7500 eggs per kg • 26 cm fish approx. • 26 cm fish approx. age-4 age-1 • Preferred water • Preferred water temperature: 9 -13C temperature: 19- 23C

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Human Stressors

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Mean Volume Weighted Hypolimnetic Dissolved Oxygen (MVWHDO)  Criterion developed by Dr. David Evans in 1993 Activity levels of lake trout limited by concentration of oxygen in water – Reduced oxygen affects swimming ability, feeding, avoidance of predators, growth and survival – Juveniles more sensitive  At temperatures of 4-14C, oxygen concentrations of 4.4, 5.8 and 7.1 mg/L limit activity to ¼, ½ and ¾, respectively  7 mg/L provide for most daily life support activities

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Additional Supportive Data  Independent surveys of lake trout populations in southern Ontario: – Lake trout populations good to excellent when MVWHDO 7-8 mg/L – Recruitment average to poor when MVWHDO < 6 mg/L

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The Lake Trout Policy  Policy proposal using MVWHDO (7.0 mg/L) posted on Environmental Bill of Rights Registry (EBR) for public comment in early 2006  EBR decision notice posted May 29, 2006  Lake trout lakes listed in ‘Inland Ontario Lakes Designated for Lake Trout Management’ available at: www.mnr.gov.on.ca/mnr/ebr/lake_trout/index.html  Revisions will require posting on EBR Registry for public comment  Policy implemented Province-wide

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Historical MVWHDO For Buck Lake Recommended concentration of 7 mg/LSouth Basin  Sept. 19, 1978 – 7.87 mg/L Sept. 01, 1987 – 5.27 mg/L Sept. 06, 2007 – 5.91 mg/L North Basin  Sept. 06, 2007 – 4.75 mg/L

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Buck Lake Stocking History  three walleye stocking episodes between 1935 & 1948 (100,000 to 250,000)  11 smallmouth bass stocking episodes between 1935 & 1956  1st record of lake trout stocking in 1949 with stocking each year between 1959 & 1989, average 4,000 annually  6,000 genetically marked lake trout stocked in 1991 & 1992

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Historical Fish Assessment Hoop nets Gill nets Aug 9-11, 1954 rbas 38 bhead 24 bgill 165 rbass 5 pumpk 83 bcrap 14 bcrap 14 smbas 7 bgill 77 1972 lmbas 17 pumpk 71 1960 yperch 8 1959 yperch 10 wall 6 lmbass 21 npike 4 npike 2 cisco 30 ltrout 16 0 20 40 60 80 100 0 40 80 120 160 200

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1992 Buck Lake SLIN Catch (total no. fish) yperch bcrap bgill pumseed comshin north (28 sets) smbas south (75 sets) npike cisco splake 9 lktrout 45 0 50 100 150 200 250

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1992 Buck Lake SLIN  0.6 lake trout per net 32 clipped lake trout (70%) Mean total length: 39.7 cm (15.6 in) Mean fork length: 35.8 cm (14.1 in) Mean weight: 553 gms (1.2 lbs)

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1997 Buck Lake SLIN  1997, Spring Littoral Index Netting (SLIN) – Short sets (30 minutes), smal mesh (1.5”,2.0” and 2.5”)– Spring, ice out until surface temperature reaches 13C  May 6-23 – Set 59 nets at randomly selected sites

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1997 Buck Lake SLIN 35  0.44 lake trout per net 31 30  17 clipped (65%) 26 25  Mean age: 6.6 yrs 20  Mean total length: 15 44.3cm (17.4 in) 13 10  Mean fork length : 5 40.9cm (16.1 in) 4 40.9cm (16.1 in 0  Mean weight: 875 gms ltrout cisco npike yperch (1.9 lbs)

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1997 Buck Lake SLIN – lake trout age at size 11 10 9 8 7 (yrs) e 6 ga 5 4 3 2 200 250 300 350 400 450 500 550 600 650 700 750 800 total length (mm)

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Summer Profundal Index Netting (SPIN)  Season: mid-July to mid-September – Before thermocline col apses  Set duration: 2 hours Net length: 64 m (210 ft) with 8 mesh sizes Depth ranges: 10-20 m; 20-30m; 30-40m > 3 mg/L dissolved oxygen

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SPIN Objectives 1. Obtain point-in-time estimate of relative area weighted density of lake trout (>300mm) 2. Obtain representative sample of lake trout population for diagnostic assessment of biological integrity

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2007 Buck Lake SPIN  39 net sets, 365 ha sampled (682 ha total)  Total 41 lake trout caught >300 mm  Estimated density of 3.4 lake trout >300 mm per ha  Population estimate of 1,233 lake trout  Confidence limits: 465 to 2,021 lake trout (68% predicted level)  Mean length total catch: 35.4 cm (13.9 in)

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2007 Buck Lake SPIN – Lake Trout Lengths 30 25 20 tal catch 15 f to o 10 % 5 0 25 30 35 40 45 50 55 60 65 Fork length (cm)

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Buck vs Loughborough Lake SPINS Buck Loughborough No. net sets 39 28 Total catch LT 41 24 Est. density LT 3.4 3.6 Conf. limits 465 – 2,021 0 – 3,237 Mean length 35.4 cm 40.8 cm

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What can Buck Lake Landowners Do? 1. Work with municipality (Official Plan) & fellow land owners to support protection & enhancement of lake trout habitat 2. Work with fellow land owners to reduce nutrient inputs 3. Water level manipulation?4. Creel survey – what’s coming out?5. Assessment of other fish species?

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Perfect ending to a day on the lake

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