Strait of Georgia, juvenile salmon, Johnstone Strait, Cowichan Bay, purse seine, nearshore waters, Pacific Biological Station, trawl surveys, Sockeye Salmon, Vancouver Island, British Columbia, Coho Salmon, juvenile Chinook Salmon, Chinook Salmon, Discovery Islands, Queen Charlotte Sound, Gulf Islands, research surveys, Pink Salmon, Puget Sound, trawl survey, Queen Charlotte Strait, Pacific salmon, Fraser River Sockeye Salmon, offshore program, Howe Sound Strait, Jonstone Strait, CCGS WE Ricker, Gulf Island, Hecate Strait, Howe Sound Gulf Islands, Juan de Fuca, Howe Sound, Roberts Banks, PBS Nanaimo, Roberts Bank, Fraser River, Hammond Bay Road Nanaimo, Chrys Neville Fisheries and Oceans Canada Science Branch, Canada, Marc Trudel, CCGS W.E. Ricker, Vessel details, Walleye Pollock, Spiny Dogfish, Stomach contents, Chum Salmon, fishing vessel, CCGS Neocaligus
NPAFC Doc. 1529 Rev. Canadian Juvenile Salmon Surveys in 2014-2015 by Marc Trudel and Chrys Neville Fisheries and Oceans Canada Science Branch, Pacific Region Pacific Biological Station 3190 Hammond Bay Road Nanaimo, BC, Canada V9T 6N7 Submitted to the NORTH PACIFIC ANADROMOUS FISH COMMISSION by CANADA APRIL 2014 THIS PAPER MAY BE CITED IN THE FOLLOWING MANNER: Trudel, M. and C. Neville. 2014. Canadian juvenile salmon surveys in 2014-2015. NPAFC Doc. 1529. 13 pp. (Available at http://www.npafc.org).
KEYWORDS: Early Marine Life; Survival Mechanisms; Migration; Distribution; Growth; Diet; Pacific salmon; Juvenile salmon ABTSTRACT In this document, we present the juvenile salmon research surveys that have been planned in both the offshore and inshore areas by Canada for 2014-2015. The offshore program will conduct sampling off the west coast of British Columbia
, whereas the inshore program will conduct sampling in the Strait of Georgia and Puget Sound. In addition to these two long-term programs, Canada will conduct three research project
s in nearshore waters: 1) weekly purse seine survey in Johnstone Strait to monitor the northward migration of juvenile Fraser River Sockeye Salmon (May-July), 2) purse seine surveys in Cowichan Bay on the east coast of Vancouver Island as part of a study examining the factor causing mortality of juvenile Chinook Salmon in Southern British Columbia, and 3) a mid-water trawl survey performed with a small net (4m x 4m) to describe the dispersion of juvenile Chinook Salmon in nearshore waters. INTRODUCTION Pacific salmon have a complex life cycle that involves a freshwater phase for spawning and rearing, as well as an ocean phase where they spend the greater part of their lives and gain the bulk of their mass and energy necessary for successfully completing their spawning migration (Groot and Margolis 1991). Pacific salmon experience heavy and highly variable losses in the ocean, with natural Mortality rate
s generally exceeding 9095% during their marine life (Bradford 1995). Most of this mortality is thought to occur during two critical periods: an early predation-based mortality that occurs within the first few weeks to months following ocean entry and a starvation-based mortality that occurs following their first winter at sea (Beamish and Mankhen 2001). Hence, Canada currently maintains two long-term research and monitoring programs on the marine biology of Pacific salmon to understand the processes regulating Pacific salmon production in the marine environment, the interactions between wild and hatchery-reared salmon, the potential interactions between wild/hatchery salmon and aquaculture production, the impacts of ocean conditions and climate change on marine ecosystems and salmon resources, and to provide a sound scientific basis for optimizing hatchery production (Trudel et al. 2013). In 2014-2015, the offshore program will conduct sampling off the west coast of British Columbia, whereas the inshore program will conduct sampling in the Strait of Georgia and Puget Sound. In addition to these two long-term programs, Canada will conduct three research projects in nearshore waters: 1) weekly purse seine survey in Johnstone Strait to monitor the northward migration of juvenile Fraser River Sockeye Salmon (MayJuly), 2) purse seine surveys in Cowichan Bay on the east coast of Vancouver Island as part of a study examining the factor causing mortality of juvenile Chinook Salmon in Southern British Columbia, and 3) a mid-water trawl survey performed with a small net (4m x 4m) to describe the dispersion of juvenile Chinook Salmon in nearshore waters. In this document, we present the juvenile salmon research surveys that have been planned in both the offshore and inshore areas by Canada for 2014-2015. 1
JUVENILE SALMON RESEARCH SURVEYS TRAWL AND PURSE SEINE SURVEYS GENERAL SURVEY INFORMATION Four integrated epipelagic mid-water trawl surveys have been planned for the CCGS W.E. Ricker (3) and chartered commercial trawler (1) in 2014-15. The early summer (June 24-July 21, 2014) and fall survey (September 16-November 8, 2014) will be conducted by the W.E. Ricker and are continuations of surveys that have been conducted for the past 10-15 years. These surveys will focus on the water bodies surrounding Vancouver Island as well as the central coast of British Columbia and will include the Strait of Georgia, Gulf Islands, Juan de Fuca Strait, Johnstone Strait, Queen Charlotte Strait, Queen Charlotte Sound, the west coast of Vancouver Island, and Puget Sound (Table 1-2; Figure 1-2). An additional survey will be conducted in the Strait of Georgia during early June (approximately May 31-June 9) using a chartered commercial trawler. The survey will follow the same track line as the surveys conducted by the W.E. Ricker in this region (Table 3, Figure 2). During the winter (March 5-16, 2015) a survey will be conducted by the W.E. Ricker and will focus on the waters between Vancouver Island and the mainland of BC (Table 4, Figure 1-2). The primary objectives of these surveys will be to (1) collect biological information on Pacific salmon (Oncorhynchus spp.) and associated epipelagic fish community, (2) collect DNA samples for stock identification purposes and to examine stock specific information on migration timing and distribution of juvenile salmon, (3) describe the ambient oceanographic conditions, and (4) quantify the biomass of zooplankton and describe zooplankton species community composition in coastal waters of British Columbia. Five mid-water trawl surveys have also been planned for the CCGS Neocaligus (Table 5). This vessel will be equipped with a 4 m x 4 m trawl to access shallow waters. The primary objectives of these surveys will be to investigate the distribution and migration of juvenile Fraser River and Cowichan Bay salmon in the nearshore areas (Figure 3-4). Purse seine surveys are planned for two regions in 2014: lower Johnstone Strait and Cowichan Bay (Figure 3-4). In Johnstone Strait the primary objective of the survey will be to determine the timing of migration of juvenile Sockeye Salmon from the Fraser River through this region. DNA samples will be collected to allow this to be examined at a stock level. This survey, in conjunction with the trawl surveys in the Strait of Georgia, will also be examining changes in condition and level of growth of the juvenile Sockeye Salmon during this critical early marine. In Cowichan Bay the primary objective of the survey will be to examine changes in condition and growth of both hatchery-reared and wild Cowichan River Chinook Salmon during the early marine period as part of a program to examine factors regulating early marine survival. Additional scientists are encouraged to participate on any of these surveys, pending security clearance, which generally requires several months advance effort, and the number of berths available. FISHING GEAR AND FISHING OPERATION The CCGS W.E. Ricker and chartered vessel will fish a mid-water trawl with small mesh bunt to retain juvenile salmon. The net is generally fished at 4.5 5 knots for 30 minutes either at the surface, 15m, 30m, 45m or 60m with occasional sets conducted at deeper depths. Fishing is conducted during daylight hours. The net design and survey methodology is fully described in Beamish et al. (2000), Sweeting et al. (2003) and 2
Trudel et al. (2013). In good sea conditions, this configuration typically achieves a mouth opening that is approximately 30 m wide by 15 m deep as measured acoustically by a Scanmar trawl eye mounted on the headrope. Vessel details for the CCGS W.E. Ricker can be found at: http://www.ccg-gcc.gc.ca/Fleet/Vessel?vessel_id=116. The CCGS Neocaligus will fish a small mid-water trawl at about 4 knots in the surface nearshore waters of the southern Strait of Georgia and Gulf Islands. The net opening is 4m x 4m with small mesh bunt to retain juvenile salmon. Fishing will be conducted during daylight hours. Set duration will be 30 minutes unless limited by fishing area. Vessel details for the CCGS Neocaligus can be found at: http://www.ccggcc.gc.ca/Fleet/Vessel?vessel_id=86. Purse seine operations will be conducted from chartered commercial salmon seine vessels using a 300 m purse seine with small mesh bunt (0.5cm) designed for retaining juvenile fish. Fishing will be weekly or bi-weekly depending on region and will occur from early May through mid-July 2014. Fishing will occur in daylight hours and in Johnstone Strait will be during slack tides. To reduce mortality, the purse seine is not completely dried on recovery. The bunt is left submerged to allow the fish to remain swimming in a pool alongside the fishing vessel. On all trawl surveys, the cod end of net is emptied into 40 litre totes. The catch is sorted by species. On the purse seine surveys non salmon catch is enumerated and released, as much as possible, directly from the bunt of net. When possible a similar procedure is used for Pink Salmon and Chum Salmon. The remainder of the juvenile salmon are transferred by dip net to a live tank on board vessel. These salmon are sorted and Coho Salmon, Chinook Salmon and Sockeye Salmon are placed into individual live tanks for subsequent sampling. For all surveys all catch is enumerated and measured onboard the ship to characterize the nekton community in epipelagic waters of British Columbia and Puget Sound (Brodeur et al. 2006; Orsi et al. 2007). The numbers of fish sampled for the different surveys and areas varies depending on the primary objectives of the survey. A general outline of sample numbers is provided in Table 8. The overall sampling protocols remain consistent among the surveys. For all surveys Coho Salmon, Chinook Salmon and Sockeye Salmon are scanned and examined for the presence of CWT, pit tag and fin clips, clips of pelvic and pectoral fins, while not as prevalent as in years past, are also recorded. For all juvenile salmon species collected, a random sub-sample (Table 8) are measured and weighed. Tissue from the operculum (using a hole-punch) or a caudal fin clip is preserved in 95% ethanol for s stock identification using microsatellite DNA (Beacham et al. 2001, 2005, 2006). In addition, calcified-structures (i.e. scales and otoliths) are sampled for age determination. Stomach contents (from cardiac to pyloric constrictions) of juvenile salmon are removed for dietary analyses either directly on board the ship or in the laboratory (Brodeur et al. 2007; Sweeting and Beamish 2009). Estimates of % fullness, total volume and degree of overall digestion are recorded. Finally, the entire stomach contents are broken down into percent contribution by individual prey groups. Dependent on particular items, the level of prey identification is at least to family, but often to the genus level (e.g., Sweeting and Beamish 2009, Duffy et al. 2010). When time permits, stomach of certain non-salmonids species are also examined (e.g., Pacific Hake, Spiny Dogfish, Walleye Pollock, Pacific 3
Herring). The diet analyst has been the same trained, qualified person for all of the surveys and is the same individual that performs diet analysis in the laboratory at the Pacific Biological Station (PBS). A subsample of the catch is preserved frozen individually at 20єC or -80єC for various chemical and calorimetric analyses such as stable isotopes, for additional DNA samples if required and for laboratory examination of stomach contents. Biological data collected for each salmon include species common name
, fork length (mm) and/or total length (mm), and observed fin clip. It will also include, when available, whole body weight (g wet), sex, stomach content weight (g wet), % water that is based on the ratio of dry to wet whole body weight, coded wire tag number, and pit tag number. Age separation is generally determined based on examination of fork length distributions that showed non-overlapping size modes for Chum Salmon, Coho Salmon, Pink Salmon, and Sockeye Salmon (Trudel et al. 2007a). For Chinook Salmon, we used a combination of coded-wire tag recoveries of known-age fish, DNA analyses and scale pattern to separate juveniles from adults, and life history types (Fisher et al. 2007; Trudel et al. 2007b, 2009), as there is considerable overlap among size modes that represent the multiple age groups. In addition to these biological data, blood plasma will be extracted from a subsample of the catch to measure the hormone Insulin Growth Factor-I (IGF-I) to map the growth performance of juvenile salmon in the Strait of Georgia and surrounding waters (Beckman 2011; Ferris et al., in press). A subsample of 5-10 salmon will also be taken immediately upon retrieval of the catch, with emphasis on the liveliest fish and tissue samples
(muscle, brain, liver etc), and immediately frozen in liquid nitrogen, dry ice or 80єC Ultra cold freezer or preserved in RNA-later for gene expression
studies in Pacific salmon that are performed in conjunction with K. Miller-Saunders at the Pacific Biological Station (Miller et al. 2013; in press). OCEANOGRAPHIC SAMPLING At oceanographic stations, the scientific crew will conduct CTD (conductivitytemperature-depth) casts. On some surveys oceanographic sampling will also (1) collect seawater samples at 10 m from the surface with a Niskin bottle for nitrate, phosphate, silicate, and salinity, and (2) filter surface seawater on GF/F glass fibre filter disks for chlorophyll a. Nitrate, phosphate, and silicate samples will be collected in acid-washed glass test tubes, whereas the glass fiber disks will be folded and placed in polypropylene scintillation vials. All these samples will be stored frozen. CTD casts will be conducted to 250 m or within 5 m of the bottom with a Seabird SBE 911+ probe. Several calibration samples from selected CTD casts will be collected over the course of the survey with Niskin bottles at depths where the salinities are stable. The oceanographic data collected in these surveys will be stored on a database maintained at the Institute of Ocean Sciences (Sidney, British Columbia). ZOOPLANKTON SAMPLING Vertical bongo tows will be conducted with two 57 cm diameter Nitex nets (mesh 253 µm) to approximately 150 m or within 10 m of the bottom. One of the nets is equipped with a flowmeter. Zooplankton collected from the flowmeter side will be preserved in 10% formalin and sent to the zooplankton laboratory at the Institute of Ocean Sciences, Fisheries and Oceans Canada (Sidney, BC) for species classification and enumeration. Zooplankton taken from the net without flowmeter will be sorted into four size fractions by successively sieving through 8.0, 1.7, 1.0, and 0.25 mm screens. Each size fraction 4
will then be weighed wet, dried at 60єC for 48 hours, re-weighed, and stored in plastic bags for future stable isotope, bomb calorimetry, and proximate analyses. The zooplankton data collected in these surveys will be stored on a database maintained at the Institute of Ocean Sciences (Sidney, British Columbia). REFERENCES Beacham, T.D., J.R. Candy, B. McIntosh, C. MacConnachie, A. Tabata, K. Kaukinen, L. Deng, K.M. Miller, R.E. Whitler, and N. Varnavskaya. 2005. Estimation of stock composition and individual identification of sockeye salmon across the Pacific Rim using microsatellite and major histocompatibility complex variation. Trans. Am. Fish. Soc. 134: 1124-1146. Beacham, T.D., J.R. Candy, K.L. Jonsen, K.J. Supernault, M. Wetklo, L. Dend, K.M. Miller, R.E. Whitler, and N. Varnavskaya. 2006. Estimation of stock composition and individual identification of Chinook salmon across the Pacific Rim by use of microsatellite variation. Trans. Am. Fish. Soc. 135: 861-888. Beacham, T.D., Candy, J.R., Supernault, K.J., Ming, T., Deagle, B., Schulze, A., Tuck, D., Kaukinen, K.H., Irvine, J.R., Miller, K.M., and Withler, R.W. 2001. Evaluation and application of microsatellites and major histocompatibility complex variation for stock identification of coho salmon in British Columbia. Trans. Am. Fish. Soc. 130: 1116-1149. Beamish, R.J., and C. Mahnken. 2001. A critical size and period hypothesis to explain natural regulation of salmon abundance and the linkage to climate and climate change. Prog. Oceanogr. 49: 423437. Beamish, R.J., D. McCaughran, J.R. King, R.M. Sweeting and G.A. McFarlane. 2000. Estimating the abundance of juvenile coho salmon in the Strait of Georgia by means of surface trawls. N. Am. J. Fish. Manage. 20:369-375. Beckman, B.R. 2011. Perspectives on concordant and discordant relations between insulin-like growth factor 1 (IGF1) and growth in fishes. Gen. Comp. Endocrin. 170: 233-252. Bradford, M.J. 1995. Comparative review of Pacific salmon survival rates. Canadian Journal of Fisheries and Aquatic Sciences
52: 1327-1338. Brodeur, R.D., E.A. Daly, M. Studervant, T.W. Miller, J.H. Moss, M. Thiess, M. Trudel, L.A. Weitkamp, J. Armstrong, and E.C. Norton. 2007. Regional comparisons of juvenile salmon feeding in coastal marine waters off the West Coast of North America. Am. Fish. Soc. Symp. Ser. 57: 183-203. Brodeur, R.D., S. Ralston, R.L. Emmett, M. Trudel, T.D. Auth, and A.J. Phillips 2006. Recent trends and anomalies in pelagic nekton abundance, distribution, and apparent recruitment in the Northeast Pacific Ocean. Geophys. Res. Let. Doi:10.1029/2006GL026614. Duffy, E.J., D.A. Beauchamp, R.M. Sweeting, R.J. Beamish and J.S Brennan. 2010. Ontogenetic diet shifts of juvenile Chinook salmon in nearshore and offshore habitats of Puget Sound. Trans. Am. Fish. Soc. 139:803-823. Ferris, B.E., M. Trudel, and B.R. Beckman. Assessing marine pelagic ecosystems: regional and inter-annual trends in marine growth rates of juvenile salmon off the British Columbia Coast. Mar. Ecol. Prog. Ser. (in press). Fisher, J., M. Trudel, A. Ammann, J. Orsi, J. Piccolo, C. Bucher, J. Harding, E. Casillas, B. MacFarlane, R. Brodeur, J. Morris, and D. Welch. 2007. Regional comparisons of distribution and abundance of juvenile salmon along the West Coast of North America. Am. Fish. Soc. Symp. Ser. 57: 31-80 5
Groot C., and L. Margolis. 1991. Pacific salmon life histories. UBC Press, University of British Columbia, Vancouver, British Columbia. Miller, K.M., A. Teffer, S. Tucker, S. Li, A.D. Schulze, M. Trudel, F. Juanes, A. Tabata, K.H. Kaukinen, N.G. Ginther, T.J. Ming, S.J. Cooke, M. Hipfner, D.A. Patterson, and S.G. Hinch. Infectious disease, shifting climates and opportunistic predators: cumulative factors potentially impacting wild salmon declines. Evol. Appl. (in press). Miller, K.M., M. Trudel, D.A. Patterson, A. Schulze, K. Kaukinen, S. Li, N. Ginther, T. Ming, and A. Tabata. 2013. Are smolts healthier in years of good ocean productivity? North Pacific Anadromous Fish Commission Technical Report 9: 165-168. Morris, J.F.T., M. Trudel, D.W. Welch, M.E. Thiess, and T.B. Zubkowski. 2004. Canadian Highseas Salmon surveys: CWT recoveries from juvenile Chinook and coho salmon on the continental shelf of British Columbia and southeast Alaska from 1998 to 2003. North Pacific Anadromous Fish Commission Document No. 823. Orsi, J.A., Harding, J.A., Pool. S.S., Brodeur, R.D., Haldorson, L.J., Murphy, J.M., Moss, J.H., Farley, E.V., Jr., Sweeting, R.M., Morris, J.F.T., Trudel, M., Beamish, R.J., Emmett, R.L., and Fergusson, E.A. 2007. Epipelagic fish assemblages associated with juvenile Pacific salmon in neritic waters of the California Current and Alaska Current. Am. Fish. Soc. Symp. Ser. 57: 105-155. Sweeting, R.M. and R.J. Beamish. 2009 A comparison of the diets of hatchery and wild coho salmon (Oncorhynchus kisutch) in the Strait of Georgia from 1997-2007. Pages 255-264 in E.J. Farley Jr., T. Azumaya, R. Beamish, M. Koval, K. Myers, K.B. Seong, and S. Urawa (eds). Climate Change, Production Trends, and Carrying Capacity of Pacific Salmon in the Bering Sea and Adjacent Waters. North Pacific Anadromous Fisheries Commission, Bulletin 5, Vancouver, Canada. Sweeting, R.M., R.J. Beamish, D.J. Noakes, and C.M. Neville. 2003. Replacement of wild coho salmon by hatchery-reared coho salmon in the Strait of Georgia over the past three decades. N. Am. J. Fish. Manag. 23:492-502 Trudel, M., C. Neville, and R. Sweeting. 2013. Canadian Juvenile Salmon Surveys in 2013-2014. NPAFC Doc. 1472. 9 pp. (Available at http://www.npafc.org). Trudel, M., S.R.M. Jones
, M.E. Thiess, J.F.T. Morris, D.W. Welch, R.M. Sweeting, J.H. Moss, B.L. Wing, E.V. Farley Jr.,J.M. Murphy, R.E. Baldwin, and K.C. Jacobson. 2007a. Infestations of motile salmon lice on Pacific salmon along the west coast of North America. Am. Fish. Soc. Symp. Ser. 57: 157-182. Trudel, M., M.E. Thiess, C. Bucher, E.V. Farley Jr., B. MacFarlane, E. Casillas, J.F.T. Morris, J.M. Murphy, and D.W. Welch. 2007b. Regional variation in the marine growth and energy accumulation of juvenile Chinook salmon and coho salmon along the west coast of North America. Am. Fish. Soc. Symp. Ser. 57: 205-232. Trudel, M., J. Fisher, J. Orsi, J.F.T. Morris, M.E. Thiess, R.M. Sweeting, S. Hinton, E. Fergusson, and D.W. Welch. 2009. Distribution and migration of juvenile Chinook salmon derived from coded-wire tag recoveries along the continental shelf of western North America. Trans. Am. Fish. Soc.138: 1369-1391. 6
Table 1. Tentative summer survey itinerary for the CCGS WE Ricker (June 24 July 21, 2014).
General area of operations
June 24 June 25-July 7
PBS Nanaimo, loading Strait of Georgia, Gulf Island, eastern Discovery Islands
July 8-10 July 11-13 July 14-16 July 17-19 July 20
Western Discovery Islands, Johnstone Strait, Queen Charlotte Strait Hecate Strait and associated inlets Queen Charlotte Sound, Jonstone Strait and travel Juan de Fuca and Puget Sound PBS Nanaimo, unloading
Table 2. Tentative fall survey itinerary for the CCGS WE Ricker (September 16 November 8, 2014).
General area of operations
September 16 September 17-30 October 1-6 October 7-12 October 13-14 October 15-23 October 24-November 7 November 8
PBS Nanaimo, loading Strait of Georgia, eastern Discovery Islands, Gulf Islands Johnstone Strait, Queen Charlotte Strait, Howe Sound Strait Puget Sound and Juan de Fuca Strait Nanaimo Crew Change & Maintenance West Coast Vancouver Island Queen Charlotte Sound, Central and North Coast PBS Nanaimo, unloading
Table 3. Tentative winter survey itinerary the CCGS WE Ricker (March 5-16, 2015).
General area of operations
March 5 March 6-7 March 8-16 March 16
PBS Nanaimo, loading Gulf Islands Strait of Georgia PBS Nanaimo, off loading
Table 4. Tentative spring survey itinerary for the chartered vessel (May 31- June 9, 2014).
General area of operations
May 31 June 1-9 June 9
PBS Nanaimo, loading Strait of Georgia, Discovery Islands (East) PBS Nanaimo, off loading
Table 5. Tentative schedule and itinerary for the CCGS Neocaligus
General area of operations
April 14-18 May 19-23 June 23-26 July 21-24 September 11-16
Gulf Islands, Roberts Banks, Howe Sound Gulf Islands, Roberts Banks, Howe Sound Gulf Islands, Roberts Banks, Howe Sound Gulf Islands, Roberts Banks, Howe Sound Gulf Islands, Roberts Banks, Howe Sound
Table 6. Tentative schedule for the purse seine survey in Johnstone Strait Date May 23-24 May 29-30 June 5-6 June 13-14 June 20-21 June 26-27 July 3-4
Table 7. Tentative schedule for the beach and purse seine surveys in Cowichan Bay Week May 8-9 May 20-21 June 2-3 June 23-24 July 15-16
Table 8. General sampling information (species and sample size) by gear type
250 Trawl All
4x4 trawl All
Purse seine All
20-100 (At sea)
20-100 (At sea)
30-50 (Frozen -80)
+ ++++++++++++++++++++++++++++++++++++++++++++++++ ++++++++++++++++++++++++++++++++++++ +++
Figure 1. Tentative survey stations for the CCGS WE Ricker on the west coast of Vancouver Island, Queen Charlotte Sound and Queen Charlotte Strait.
Johnstone Strait purse seine (Cowichan Bay) Figure 2. Generalized map of Strait of Georgia, British Columbia. Track lines for the July and September surveys are shown in red. The Gulf Islands region is in the south-west portion of the strait, bounded by Vancouver Island on the western side. Boundary Bay extends south from Point Roberts along the eastern shoreline. Puget Sound set locations are not shown in this map but region is circled. Juan de Fuca strait tracklines are essentially along either shoreline, as the middle areas are traffic lanes. Eastern Discovery Islands included the purple dashed lines at northern end of Strait of Georgia and lower portions of Bute and Toba Inlet. The purse seines surveys will be conducted in the southern Johnstone Strait (purple circle) and Cowichan Bay in the Gulf Islands. 11
Cowichan Bay purse seine and 4x4 trawl study area
Roberts Bank 4x4 trawl study area
Figure 3. Region of study in Cowichan Bay (red circle) and Roberts Bank region (green circle) in the southern Strait of Georgia and Gulf Islands.
Southern Johnstone Strait purse seine study area Figure 4. Region of purse seine surveys in southern Johnstone Strait (red circile). All juvenile salmon migrating north from the Strait of Georgia pass through this channel. 13
M Trudel, C Neville