Habitat Use and Seasonal Movement Patterns of Predatory Fishes in the Lake Washington Ship Canal Roger Tabor, Scott Sanders, Mark Celedonia, and Dan Lantz Background • Prior to 1999, little work conducted in Ship Canal • 1999 Predator study • Smallmouth bass • Largemouth bass • Northern pikeminnow • All three species consumed juvenile salmonids • Smallmouth bass had the highest consumption rate Background – Smallmouth Bass • Introduced piscivore • Inhabits rivers and lakes • Predator of juvenile salmonids • Three annual phases – spawning, summer rearing, and overwintering • Prefer steep-sloping banks with large substrates • Often associated with structures such as LWD Background – Largemouth Bass • Introduced piscivore • Inhabits lakes and slow-moving rivers • Predator of juvenile salmonids • Prefer gentle-sloping banks with fine substrates • Often associated with aquatic macrophytes Background – Northern Pikeminnow • Native piscivore in large rivers and lakes • Important predator of juvenile salmonids • Opportunistic predator – eat a wide variety of prey – live and dead • Ability to forage under very low light conditions • Previous studies primarily on pikeminnow in Columbia River; relatively little work in lakes except diet studies • Lake Washington – Brocksmith (1999) preliminary work on pikeminnow movements Objectives • Document habitat use patterns of predatory fishes • Use of overwater structures • Gas Works Park site • Determine overlap with juvenile Chinook • Determine movement between Lake Washington and Ship Canal Outline • Habitat use – fine-scale tracking (HTI system) – Smallmouth bass – Northern pikeminnow • Seasonal movements – large-scale tracking (Vemco system) – Smallmouth bass – Largemouth bass – Northern pikeminnow Methodology • Capture techniques Angling Seining Gill Netting • Surgical techniques HTI G tag HTI tags: Vemco V-13 tag 20 - 60 days Vemco tags: 90 - 600 days HTI Arrays used for Predator Tracking 2004 Portage Bay 2005 Gasworks Park Portage Bay Tennis Club 2006 Gasworks Park Portage Bay University Bridge 2007/2008 Gasworks Park University Bridge SR-520 Bridge N 5km Smallmouth Bass – Fine-Scale Tracking Gas Works Park I5/University Bridge I5 / UniversityBridge - Habitat types Gas Works Park Substrate data from Floyd│Snider Smallmouth bass – Gas Works Park Depth selection N = 22 * 0-2 m 80 * * 2-4 m 4-6 m 60 6-8 m 8-10 m 40 10-12 m 12-14 m 20 > 14 m Percent positive selection positive Percent o o o o 0 Day Night Smallmouth bass – University Bridge Depth selection 80 N = 25 0-2 m 60 2-4 m 4-6 m 40 6-8 m 8-10 m o 20 o o Percentpositive selection 0 Day Night Smallmouth bass – Gas Works Park Habitat selection N = 22 * Dense veg. Moderate veg. 50 * Sparse veg. Veg. edge 40 Open water 30 o 20 10 Percent positive selection positive Percent 0 Dawn Day Dusk Night Diel period Smallmouth bass – Gas Works Park 150 - 349 mm 350 - 470 mm Smallmouth bass – University Bridge Habitat selection 80 UB-S 70 N = 25 * UB-O 60 OWS * * I-5 B-V 50 I-5 B-O M/D Veg 40 * Sp Veg * Veg Edge 30 Open 20 Percentpositive selection 10 0 Day Night Smallmouth bass – University Bridge 150 – 349 mm (n = 10) Smallmouth bass – University Bridge 350 – 470 mm (n = 16) Smallmouth bass – Gas Works Park Substrate selection 80 N = 22 * Silt 70 * Sand/Silt 60 Gravel/Sand 50 * 40 Cobble/Boulders 30 20 Percentpositive selection 10 0 Dawn Day Dusk Night Diel period Smallmouth bass – Gas Works Park Shoreline selection 90 N = 18 80 * * * 70 60 * Beach 50 Bulkhead 40 Rip rap 30 20 Percentpositive selection 10 0 Dawn Day Dusk Night Diel period Northern Pikeminnow - SR 520 Bridge Fine-Scale Tracking SR 520 Bridge - Habitat types Results • Extensive tracks were obtained on 14 of 42 (33%) pikeminnow • Of these 14 fish, a total of 632,000 data points were obtained 25 20 15 Number 10 5 0 250-299 300-349 350-399 400-449 450-499 Size category (FL, mm) Depth selection 100 Day 80 n = 13 60 40 20 % positive% selection 0 0-2 2-4 4-6 6-8 8-10 >10 100 Night 80 n = 9 60 40 20 % positive% selection 0 0-2 2-4 4-6 6-8 8-10 >10 Depth interval (m) Day and Night Selection Ratios Offshore open areas 0.8 0.7 0.6 Day 0.5 Night 0.4 0.3 Selection ratio Selection 0.2 0.1 0 4657 4658 4667 4777 4787 4797 4898 4978 Fish number 70 Habitat selection a 60 a Day 50 n = 13 ab 40 b 30 bc 20 bc bc % positive selection positive % c 10 0 Dense veg. Mod. veg. Sparse veg. Veg. edge Offshore Overwater Bridge Near bridge structure 100 a 90 Night 80 n = 9 ab 70 60 ab 50 40 ab bc 30 bc bc % positive selection positive % 20 10 c 0 Dense veg. Mod. veg. Sparse veg. Veg. edge Offshore Overwater Bridge Near bridge structure Habitat type Northern Pikeminnow # 4657 Northern Pikeminnow # 4667 Day Night HTI and Vemco results combined – 3D Day - #4657 Bottom depth (m) Day - #4667 Bottom depth (m) 0 2 4 6 8 10 > 10 0 2 4 6 8 10 > 10 0 0 2 2 4 4 6 6 8 8 10 10 Water column depth (m) depth column Water 12 (m) depth column Water 12 14 14 Night - #4657 Bottom depth (m) Night - #4667 Bottom depth (m) 0 2 4 6 8 10 > 10 0 2 4 6 8 10 > 10 0 0 2 2 4 4 6 # of data points 6 0 8 1-9 8 10-49 10 50-99 10 100-499 Water column depth (m) depth column Water 12 500-999 (m) depth column Water 12 1,000-1,999 14 14 Juvenile Chinook Salmon Distribution Day Night Northern pikeminnow May 29 – July 1, 2008 Mean percent of body weight, all dates combined 0.7 17 0.6 9 Other inverts 0.5 17 Crayfish Sculpin 0.4 Stickleback 12 Smelt 0.3 Lamprey % BodyWt. % Salmonids 0.2 8 0.1 0 520 Bridge Wolf Bay Webster Pt Madison Park Tennis Club Location Large-scale tracking / Seasonal movements Lake or Ship Canal??? Lake Washington Montlake Cut Vemco system • Fixed and mobile system • Eleven fixed receivers • Supplemented with mobile tracking • Presence and absence data with 300-400 m range Vemco Receivers (Hydrophones) Location of Hydrophone Ship Canal Hydrophone Transition Hydrophone Lake Hydrophone St. Edwards Park UW Rowing Center N University Bridge Fish.Terminal Metrolab Webster Point Aurora Bridge Lakeshore Apartments South Lake Union UW Hatchery West I90 Smallmouth Bass 72 Smallmouth bass tagged – 193-450 mm fork length tagged from May-July 50 Returned to Ship Canal a second time 40 Moved to lake a second time 30 Returned to Ship Canal 20 Moved to lake, no other detections Numberof fish 10 0 No data Residents Migrants Movement category Smallmouth Bass – examples Daily detections Lake # 192 Union Bay Ship Canal 2006 2007 2008 Jun Aug Oct Dec Feb Apr Jun Aug Oct Dec Feb Apr Jun Lake # 200 Union Bay Ship Canal 2006 2007 2008 Jun Aug Oct Dec Feb Apr Jun Aug Oct Dec Feb Apr Jun Smallmouth Bass Movement to Lake Washington North Lake Union R2 = 0.38 Portage Bay R2 = 0.04 Entry lake into date Entry May Jun Jul Aug Oct Sep Aug Jul Jun May 200 250 300 350 400 450 500 Fork length (mm) Smallmouth Bass – return to Ship Canal 6 20 2007 - SMB Weekly number returning 2008 - SMB 18 5 2007 - temp. 16 2008 - temp. 14 4 C) 12 o 3 10 8 2 Number of fish 6 Temperature ( Temperature 4 1 2 0 0 1-Feb 1-Mar 29-Mar 26-Apr 24-May Date Smallmouth Bass – returned fish Furthest west detected in Ship Canal East University Bridge Gas Works Park # 210 12 Aurora Bridge West Metro lab - W. Fremont Cut 10 8 6 Number of fishof Number 4 2 0 Portage Bay North Lake Union Release location Smallmouth Bass Ship Canal fish in Lake Washington Mobile tracking results 60 Area 1 50 Secondary area 40 Primary area Area 2 30 Percent 20 10 Area 3 0 1 2 3 4 5 Area 4 Area Area 5 Smallmouth Bass Ship Canal fish in Lake Washington Fish ID ¡[ 192 ¡[ 208 Largemouth Bass • 5 Largemouth bass tagged – 192-410 mm fork length – 4 from Portage Bay – always in Portage Bay or Union Bay – One from Lake Union – always in Ship Canal – tracked for two years East 25 Webster Point # 17188 20 UW Rowing Center C) o UW Hatchery 15 University Bridge South Lake Union 10 Aurora Bridge ( Temperature 5 Metro Lab 2006 2007 2008 West 0 Jul Sep Nov Jan Mar May Jul Sep Nov Jan Mar May Jul Sep Northern Pikeminnow • 22 Northern pikeminnow tagged in Ship Canal • 12 tagged in Lake Washington (at SR 520 Bridge) • 310 – 460 mm fork length • Tagged from May to July 12 10 Returned 8 to LWSC 6 Unknown (few detections) Number of fish of Number 4 Never 2 returned to LWSC Died or expelled tag 0 Moved to lake within 4 days Moved to lake after > 10 days Not detected moving to lake Movement to Lake Washington after release Northern Pikeminnow Daily movements # 17222 Jul Sep Nov Jan Mar May Jul Sep Nov Jan Date Northern Pikeminnow Daily movements # 22507 Lake Union Bay Ship Canal 2008 2009 May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Date Northern Pikeminnow Diel movements # 22506 – June 16-21, 2008 Webster Point UW Rowing Center UW Hatchery 0:00 12:00 0:00 12:00 0:00 12:00 0:00 12:00 0:00 12:00 0:00 12:00 0:00 Time Summary – Fine-scale tracking • Smallmouth bass were associated with structures which may allow them to inhabit deeper waters and have more overlap with smolts • Smallmouth bass also used gravel beaches which may have been related to spawning activity • At the SR 520 site, northern pikeminnow were closely associated with aquatic macrophytes as well as a small overwater structures • Northern pikeminnow were in water that was 2-6 m deep during the day and were spread out into deeper waters at night Summary - Large-scale tracking • Most smallmouth bass only inhabit the Ship Canal for a few months, sometime from March to September • Most appear to make regular, predictable migrations between Lake Washington and the Ship Canal and may be reproductively isolated from Lake Washington bass • Preliminary data suggest largemouth bass remain in the Ship Canal and Union Bay area • Northern pikeminnow appear to only make periodic forays into the Ship Canal from May to August • Based on low-catch rates and movement patterns, northern pikeminnow do not appear to be a major predator in the Ship Canal.