LA PEROUSE PROJECT: FIFTH ANNUAL PROGRESS REPORT, 1989 CONTENTS
Page
1. Introduction 1 2. Standard Sampling Grids 5 3. Investigator Summaries 8 3.1 Physical Oceanography Program 8 3.1.1 Current and Water Property Observations in 1989 8 3.1.2 Drifter Studies with a Tidal Model for the southwest coast of Vancouver Island 22 3.1.3 Shelf current measurements during 1989 26 3.1.4 Comparison of Currents, Wind Stress and Sea Level Fluctutations off the Pacific Coast of Vancouver Island, B.C. 28 3.2 Biological Oceanography Program 30 3.2.1 Biological Oceanography 30 3.2.2 El Nino Update (5 March 1990) 35 3.3 Fisheries Oceanography Program 41 3.3.1 Pacific Hake Distribution and Recruitment 41 3.3.2 Herring Mortality, Distributon and Recruitment 44 3.3.3 La Perouse surface living macro - Zooplankton 48 3.3.4 Pacific Cod Recruitment 51 4. List of References and Relevent Publications 55 5. Summary of Mooring, CTD and Plankton Net Haul Activity for 1989 58 6. 1990 Vessel Schedule and Objectives 64 7. List of Participants 65 -1-
1. INTRODUCTION The La· Perouse project is a multidisciplinary, multispecies investigation intended to provide long-term physical and biological data for research on the major commercial fish stocks off the west coast of Vancouver Island. Initiated in early 1985 shortly after the strong 1982/83 EI Nino-southern Oscillation (ENSO) event, the project has entered the second half of its projected 10-year term. Considerable progress has now been made toward identification of the dominant physical processes affecting the circulation and water property structure, to quantifying the statistical variability of the seasonal and interannual cycles and toward direct estimation of the impact of interannual fluctuations on the planktonic food web, Pacific herring, sablefish, Pacific hake, and Pacific cod. Indications that moderate EI Nino type conditions are presently developing in the equatorial region suggests that the project may soon achieve another of its original goals: observation of the possible effects of a moderate-to-strong ENSO event on the Vancouver Island coastal fisheries. La Perouse Bank (Figures 1a,b) is situated within the coastal upwelling production zone that extends from northern Vancouver Island to Baja California, and is one of the most productive fishing areas in Canada. Over the past decade, the catch of commercial fish from the La Perouse area has averaged 6.6 tonnes/km2/yr, about 5 times the average yield per unit area along the eastern boundary of the Gulf of Alaska. In summer, the La Perouse region is visited by large migratory fish stocks from California, such as Pacific hake and Pacific mackerel. Large numbers of Pacific sardine also visited the region prior to the collapse of the fishery in the 1950's. Sablefish are another important fishery for the region and provide further justification for the cooperative fishery/ oceanography work being conducted in the vicinity of La Perouse Bank. For example, research on the early life history of sablefish indicates that onshore movement of surface waters and enhanced poleward coastal winds in winter affect strong year-classes. Other factors such as the interaction of succeeding year-classes may also be important in determining the age structure of the stock either through direct competition and/or cannibalism. strong year-classes can double the size of the stock in the Canadian zone. Consequently, they can have a major impact on other commercially important fishes (such as Pacific herring) 2 to 3 years later when the new hake recruits join the adult component of the stock on the summer feeding grounds off Vancouver Island. From a fisheries perspective, one of the most important goals of the program is to improve the Department of Fisheries and Oceans' ability to make accurate forecasts of herring and sablefish recruitment success a few years in advance. This ability could provide considerable benefit to the commercial fishing industry through increased 'i !j ;1 :1 126°30' 126°00' 125°00' 49000' \'\::$ii;::: ' . 125"30' IS::'" .. ?., \l as .~ '~ 'I 49°00'
VANCOUVER ISLAND
Sf' ", I ~( - 148°30' I 48·~1 1 7 .\ I.. tv I \ 0c::. ,;. ~ ."
11' <"'0 ..0 ~ C"c::. ~.p , «'1.- ~
0 48°00' 48 00'1 ,/7'" ,\ I {'} ( ~- III 'J' ;.II 126°30' 126°00' 125°30' 125000'
~j " ~II ·;1 ·,1 Figure la. General summer circulation pattern on La Perouse ;j .J Bank and surrounding waters. stipple region denotes an area ~i of confused flow. 11 '1 4.9°00'
'\ .... _-, / ,/ ,, " IOOOm.... 14.1 .... '-1,.. \,- '\ \ .... 13.1 ) f 48°30' , I W FISHING SUBAREAS .... , I c .. I. BARKLEY SOUND "\ , I-- \ I ,--', ,,,- 2.FIRING RANGE I ( I ( \ 200n( / 3.SW CORNER \ 7 I I ...... / I 4. POTHOLES \ 10 • I I " ./ 5.12 MILE BANK .... --" I / I " I I 9 I 6.40 MILE BANK (_' \' I l) I • 7. FINGER BANK \ /~ ), I (-' ,-""r r I I 8. BOTTLENECK I I I I \ -J'.,( / 9.SWIFTSURE BANK ~ -../ ",...... __ --)1,- I ...... " , I 1 \ 10. EDDY \ f'J I I II. WEST BANK 12.1 ,..,,/ , , r-,,.. I I // '\ r ) .... I' .I'" - "\ I I 12. SOUTH SLOPE L. \ \ 13.CENTRAL SLOPE ,-\ j I '" I ---,,.. 200m 200m 100m 14. NORTH SLOPE ,." 48°00' ,.. "\ I I I ,
126°00' 125°00'
Figure lb. La Perouse Bank fishing subareas. The map shows the locations of some important places mentioned in the report. -4- catch quotas. A 1000 tonne increase in the quota would add about $2 million to the value of the roe herring industry and about $4 million to the sablefish industry. Unlike conditions in northern British Columbia waters, the La Perouse Bank production system is characterized by relatively intense wind-induced upwelling, a narrow continental shelf and high euphausiid biomass. The results of the Fifth Annual Meeting of the project investigators held at Cowichan Bay from March 6 to 7, 1990 suggest that we now have a basic understanding of the physical oceanographic processes effecting the region and are beginning to identify some of the main reasons for the high secondary and tertiary productivity over the fishing banks. One key feature appears to be the existance of three distinct sources of nutrient supply for primary productivity in the region: (1) direct wind-induced upwelling onto the outer shelf from depths of 300 to 400 m with subsequent mixing into the near-surface inshore waters: (2) persistent transport of nutrient-rich water seaward from Juan de Fuca strait; and (3) intermittent topographically-enhanced, wind-induced upwelling off the Scott Islands and Brooks Peninsula, with subsequent longshore transport within the equatorward flowing shelf break current. The nutrient supply within the Juan de Fuca strait outflow may originate with upwelling of intermediate depth water transported poleward via the California Undercurrent Extension or through entrainment of Fraser River water moving seaward with the estuarine circulation. This manuscript contains the progress reports for 1989 for the individual investigators within the La Perouse Project. Annual meetings are held to review the design, recent progress and future plans of the three main components of the program: 1. The Physical Oceanography Program (headed by R. Thomson); 2. The Biological Oceanography Program (headed by D. Mackas and K. Denman); 3. The Fisheries Oceanography Program (headed by D. Ware and s. McFar lane) . For further details please contact the project coordinators: D. M. Ware Department of Fisheries and Oceans Pacific Biological station Nanaimo, B.C. V9R 5K6 Phone: (604) 756-7199 R. E. Thomson Department of Fisheries and Oceans Institute of Ocean Sciences Sidney, B.C. V8L 4B2 Phone: (604) 356-6555 -5-
2. STANDARD SAMPLING GRIDS
The standard sampling grids for CTD/hydro profile stations and plankton tow stations are presented in Figures 2a and 2b, respectively. Figure 2b also shows the locations of the current meter moorings for 1990, AI, B1, and C1. Mooring E01 and zooplankton transects E and G are shown in Figure 6b. Listings of the stations positions are presented in section 5. Generally, the area of interest is defined from north to south, between 490 00.0' and 4S 0 00.0'N latitude, and from east to west, between 1240 40.0' and 1260 50.0'W longitude. Furthermore, the sampling grid transect lines run perpendicular to the coast of Vancouver Island and pass through the above defined area at an approximate bearing of 2350 true N. 126°30' 126°00' 12!5°30' 12!5°00'
49°00' 49°00'
Depth Contourl In Metres
48"30' 48°30' 1 0'\ 1
48°00' 48°00'
128°30' 126°00' 125°30' 12!5000'
Figure 2a. La Perouse Bank CTD survey lines and current meter moorings (triangles A1, B1, C1). 126°30' 126°00' 12~D30' 12~·00'
49°00' 49°00'
D.pth 1000 200 Contours In ... tr ••
48°30' 48 D 30' @ I -....J r& I ~
@
48°00' 48°00'
126°30' 126°00' 125°30' 125°00' Figure 2b. La Perouse Bank plankton sampling stations. -8-
3. INVESTIGATOR SUMMARIES
3.1 PHYSICAL OCEANOGRAPHIC PROGRAM 3.1.1. Current and Water Property Observations in 1989 The primary objective of the physical oceanographic component of the La Perouse Project is to provide long-term measurement of the circulation and water properties over the southern Vancouver Island shelf in support of fisheries and climate-related investigations. Observations yield insight into the dynamics of the current regimes over the shelf and provide a data base for studying interannual and decade scale (EI 'Nino type) variability in the northeast Pacific Ocean. Additional applications include the study of shelf/slope exchange processes, determination of the interannual variation in the timing and intensity of the Spring and Fall transitions, and the provision of boundary and verification data for numerical circulation models. Data collected during the program are used in the development of oil-spill trajectory models, in the determination of sonar paths for military operations, in the interpretation of sea bird distribution data and in studies of sediment distribution and transport. Data Collection The number of oceanic water property surveys off the west coast was down significantly in 1989 compared to previous years. In addition to fewer surveys by the Ocean Physics Division of the Institute of Ocean Sciences, structural problems forced cancellation of scientific cruises on the Ricker during the main portion of the field season. Data in the survey region (Figures 2a, b) was collected during 10 separate cruises between January 1 and December 31, compared with 17 surveys in the same period in 1988. A total of 503 CTD casts and 51 plankton net hauls were completed during 1989 compared with 772 CTD casts and 78 net hauls in 1988. All data collected by the various contributing groups have been processed and are available from Richard Thomson of the Institute of Ocean Sciences. Water properties include vertical profiles, horizontal maps and cross-sections of temperature, salinity, density, dissolved oxygen, light attenuation coefficient, sound velocity, dynamic height and geostrophic currents. As in previous years, the initial stages of the water property editing are conducted in-house while the remaining analysis is conducted under contract. Current Meter Moorings The standard deployment positions for the La Perouse current meter moorings A1, B1, and C1 are shown in Figures 2a and 2b. Owing to heavy fishing activity in the fall of -9-
1988, mooring A1 was not deployed through the winter of 1988/89 and mooring C1 was not deployed until October 1988. Servicing and redeployment of all three moorings took place in April 1989. At this time, additional moorings E01 and E01a were deployed off Estevan Point to measure variability in the Vancouver Island Coastal Current (Figure 2a). Problems with the array began almost immediately. Mooring A1 was "hit" within 15 days of deployment and the bottom (400 m) instrument lost. The top instrument from mooring B1 was cut free in June (and recovered) and mooring C1 was hit in early July with the loss of the 100 m instrument. The near bottom instrument was recovered by dragging on 21 July. Mooring A1 was redeployed on June 1 but was again hit on July 27 with the loss of the 35 m depth instrument. Moorings B1, C1 and E01 were serviced and redeployed in late August but A1 was not redeployed until late October due to heavy fishing activity in the area. Mooring E01a was recovered in late August. All three La perouse moorings and the mooring E01 off Estevan Point were in place in late October.
Mooring status as of October 1989 station Latitude Longitude Deployment Depth ID oN oW DD-MM-YY (m)
A1-J 48 31.82 126 11. 71 25-10-89 RCM 35 RCM 100 TR 101 RCM 175 RCM 400 Bottom 500
B1-J 48 45.23 125 33.81 22-08-89 RCM 35 RCM 100 Bottom 145
C1-J 48 28.79 125 15.29 22-08-89 RCM 35 RCM 100 Bottom 150
E01-J 49 21.60 126 43.17 17-08-89 S4 25 RCM 35 RCM 75 Bottom 90 ------
Bottom-mounted pressure gauges are no longer deployed at any of the mooring sites. Instrument losses have also forced -10- us to abandon the use of transmissometers at the near surface depths. Guard Buoys During the earlier years of the project, failed acoustic releases were the primary cause for instrument and data loss. Since 1987, increased fishing activity has been the primary cause of increased data loss from the current meter moorings (Figure 3). Most moorings are hit during the summer by hake mid-depth trawls but sablefish lines have also been responsible for the losses from the slope mooring. The survival time for the moorings at all locations has significantly decreased. Guard buoys were deployed from April through October 1989 to protect the three southern moorings (A1, B1, C1) from fishing damage. The Estevan Point mooring was left unprotected since it is outside the zone of heavy fishing activity. The buoys used in 1989 were marked for disposal by the Canadian Coast Guard when we acquired them for the project. They are 27 ft long spar buoys designed as channel markers on inland waterways. Although of marginal durability for our application, it was hoped that buoys would survive the summer conditions and provide a test of the guard bouy concept. The buoys were refurbished in early 1989 and equipped with radar reflectors and cautionary lights consistent with international regulations for scientific moorings. Our configuration met with Coast Guard approval. Information concerning the La Perouse program was disseminated as widely as possible to ships in the area by Fisheries and Oceans and the Canadian Coast Guard. Buoys were deployed as semi-taut single point moorings in close proximity to each current meter mooring. Moorings A1 and C1 were placed at the centre of an equilateral guard-buoy triangle of 2 cable* radius while moorings B1 had two guard buoys placed at distances of 2 cables on either side parallel to the bottom topography. During August, we moved the buoys to within 1 to 1.5 cables of the moorings. (* a cable is 1/10 of a nautical mile.) The lights and radar reflectors mounted on the buoys were at 4 m elevation and were found to be detectable by ship's radar up to 5 nautical miles in moderate seas. In near gale conditions, the buoys become lost to sea-clutter. Operators at the Tofino Coast Guard Navigational Radar could identify mooring B1 most of the time while the two more distant moorings were visible in light to moderate sea conditions. Despite our efforts, all moorings were damaged or lost to fishing gear in 1989. The mooring at A1 appeared to be especially vulnerable and was hit repeatedly. Although data loss was high, actual instrument losses were mitigated through use of the satellite tracked "witness" buoys attached to each mooring and through cooperation of the -11-
14 S-A: SEPTEMBER-APRil P I 12 A-S: APRil- SEPTEMBER I I .VI I 0 Z lOSSES / 10 Q o----d CI) ,!!jl w T I CI) CI) ~/ 0 8 .':::J~ / ~ (j I IX T I W I I- w 6 / d ~ // I- ,-/ Z w 4 p----o----d IX , IX / :::::l ,-/ U 2 ---d'
a
2 3 4 5 6 7 8 9 1985 1986 1987 1988 1989 t t T T t T t t A-S S-A A-S S-A A-S S-A A-S S-A A-S
LA PEROUSE MOORING NUMBER
Figure 3. Losses of current meters due to fishing activity since the beginning of the La Perouse Project in April 1985. Solid line shows the numbers of current meters lost for each deployment period (April to September and September to April); dashed line shows the accumulated losses for the period April 1985 to September 1989. -12- fishing fleet. In addition to instrumentation loss, 4 of 9 guard buoys disappeared. All three of the guard buoys at A1 were lost with the current meter mooring. We also lost or had damaged 7 flashing lights and 9 radar reflectors. Ignorance of, or disregard for, the moorings is evident. One of the Ocean Physics technicians observed a vessel tow its net through the centre of guard buoys surrounding mooring C1. The conclusion is that guard buoys are not very effective and that it is questionable whether larger, permanently installed buoys would fare much better. The discussion during the meeting suggested that best results would be obtained by getting direct information to the various fishing vessels in their native language prior to the start of the season. Oceanic Winds , The Atmospheric Environment Service has maintained a 3-m discus wind buoy at 48 0 S0.0S' N, 12SoS9.74' W on La Perouse Bank since November 1, 1988. Data are transmitted to shore via the GOES satellite and are archived by the Marine Environmental Data Service in Ottawa. winds for the period November 1, 1988 to January 1, 1990 are on-file at the Institute of Ocean Sciences as part of the La Perouse data bank. Standard Oceanographic Products The edited oceanographic data are processed using a set of standard techniques that have been customized for the La Perouse region. Standard products derived from these data are listed below. Further details can be found in the 1988 Annual Report published in March 1989. 1. Files and plots of 1-m averaged temperature, salinity and light attenuation as a function of depth for all oceanic surveys from June 1984 to January 1990. Dissolved oxygen profiles from water bottle casts at standard depths are available for many of the La Perouse grid stations. 2. Files at standard hydrographic depths (e.g. 0, 10, 20, 30, SOm, ••. ) of temperature, salinity, density (sigma t), light attenuation coefficient, dissolved oxygen, sound speed, and dynamic height. 3. Objectively mapped water properties at standard oceanic depths for each oceanic survey including temperature, salinity, density (sigma-t), dissolved oxygen, light attenuation coefficient, depth of sigma-t surfaces and geostrophic velocity (Figures 4a,b). -13-
r-----~~------~~----~------~500N
r-----~~~------_r~------~------~500N
~ ______~ ______~ ____~ __~ __~ ____~48° 1240
Figure 4. Objectively derived maps of water properties for the west coast of Vancouver Island for early August 1989. (a) Temperature at 50 m depth; (b) Salinity at 50 m depth. Ellipse shows the assumed correlation mappling scales of 50 krn longshore and 25 krn across-shore used to smooth the data. -14-
4. Objectively mapped cross-sections of the above oceanic properties along all cross-shore survey lines (Figures 5a, b) • 5. Three-dimensional maps of water properties for the La Perouse region including bottom topography. 6. Current meter records for all sites have been edited and processed. Hourly and low pass filtered values are available. 7. Satellite thermal imagery (NOAA AVHRR data) have been obtained and analyzed for specific cruises. Unfortunately, there is no mechanism to process the acquired data other than through a contractor. 8. A summary of all mooring activity for the year.
New Products for 1989/90 In addition to the standard products, a number of new products were developed in 1989 to aid in the display and interpretation of the La Perouse data. These products should be available early in April 1990. 1. Spline-interpolated time series of water properties at selected frequently-sampled stations within the survey region for the five-year period 1984 to 1989 (Figures 6a, b) • All data from the La Perouse study region have been mapped via objective analysis onto a regularly spaced grid of 20 x 20 km resolution, covering an area of 260 x 160 km2 . Where possible we have used data back to May 1979. The data base covers a total of 100 cruises. A number of "Goodness of fit" criteria have been applied to each of the values contributing to the data base. The procedure checks for reasonableness with actual neighboring data values and rejects interpolated values that have less than 50% confidence level. The correlation scales of 25 and 50 km used for the across-and alongshore directions are a compromise intended to ensure full use of as much data as possible and still represent the mesoscale variability on the shelf. A modified cubic spline fitting routine is used to generate the time series of water properties at specified grid locations. Where gaps exceed one year the points are not joined. Spline fitting is mainly to show the approximate relation of consecutive points. Preliminary results show that there is a strong seasonal cycle in the upper layer and lower layers over the shelf. variations above and below 50 m depth differ in phase by approximately 1800 at the annual cycle due to the effects of heating/cooling at the surface -15-
LlNE-G A 08, 07, 06, 05, 04 03 0 10 20 30 50 75 100 125 150 ______7 E 175 J: 200 >- Il.. 225 w a 250 300 ------6----- 400 500 ------5----~ 600 700 800 1000 TEMPERATURE (OC) 1200 1500 2km
LlNE-G B 08 07, 06, 05, 04 03 2A 021AOl 00 o J Y 10 '32 ='7'Y 20 ------30 _---~33-_-----_----:..-:.------50 75 ----==------100 125 150 E 175 J: 200 > __ -----34------Z Il.. 225 aw 250 - 300 400 500 600 700 800 1000 SALINITY(Ppt) 1200 1500 2km-
Figure 5. Objectively derived cross-sections of (a) Temperature and (b) Salinity for Line G (see Figure 4a) seaward of Estevan Point, early August 1989. -16-
STATION NO.30 TIME SERIES BASED ON OBJECTIVE ANALYSIS FOR LOCATION 48.458N 125.655W AT VARIOUS DEPTHS VANCOUVER ISLAND OFFSHORE R1=25 R2=50 PHI=45
14.50
10.50
8.50 10m 13.50
10.50
7.50 20m 11.50 u 0 w or: => I- <{ 9.50 or: W D.. ~ W I- 7.50 50m 10.50
8.50
6.50
10
8
6 1985 1986 1987 1988 1989 TIME
Figure 6a. Time series of water temperature at standard depths for the period September 1984 to September 1989, derived from objective maps in the vicinity of Station No. 30 located south of La Perouse Bank (see Figure 6b). -17-
500
VANCOUVER
Figure 6b. Location of station 30 and mooring EOl off Estevan Point (see Figure 6a). Offshore transects E and G are also shown. -18-
versus upwelling/downwelling near the bottom. There is no evidence for long-term climate change in the comparatively short water property records. 2. Five (5) year summary of moored time series data. current meter, thermistor chain and pressure gauge and winds. Time series records from current meters, thermistor chains, pressure gauges, and anemometers from all La Perouse moorings have been summarized. Results include means and standard deviations, tidal harmonics, hourly plots and low pass filtered plots (Figure 7). Band-passed filtered records of near-inertial motions are also presented. Specific variables are: (a) Cross-and alongshore currents; (b) current along principal and minor axes); (c) temperature and salinity records; (d) bottom-mounted pressure records; and (e) cross-and alongshore winds. Research Activities Data from the La Perouse Project is being used in support of coastal oceanographic research. Descriptions of projects with which I am directly involved follow: 1. During our June 1989 La Perouse Project survey off the west coast of Vancouver Island, we experienced a series of strong (20 m/s) northwest wind events. Peak wind of 30 m/s on June 6 led to intensification of the summer upwelling and a strengthening of the equatorward flowing shelf-break current as determined from ADCP profiles and Loran-C drifter tracking by Mike Woodward. CTD/hydro surveys before and after the event showed increased onshore penetration of the density surfaces over the shelf coincident with offshore advection of trackable near-surface features. Current measurements at site E01 off Estevan Point indicate a slight decrease in the strength of the poleward flowing Vancouver Island Coastal Current at this time followed within one day by a rapid strengthening of the current. The Loran-C drifter measurements showed that the shelf break current i~tensified during the event and that the coastal current continued to flow poleward counter to the prevailing winds. Drifter tracks within the separation region between the two currents remained confused and variable. Throughout the survey period, crab megalopae concentrations obtained by Glen Jamieson from "bongo net" tows remained centered over the core of the shelf-break current. Tucker net trawls taken from the 10 day survey are being used to "calibrate" the biomass estimates from the ADCP backscatter signal. (Ship-board acoustic Doppler Current meter measurements are made during most lOS cruises. The analysis, calibration and interpretation of these data is still in the developmental stage.)
- .:::.--.. ----:::.~ --~---::'- .. ':'-.. ' ..-' ..... -.. --., ... ~.- ... ~. ,-.,.~'~,~' .. La Perouse Bank ------STATION: Bl LATITUDE 48 45.8 N DEPTH: 30 m LONGITUDE 125 31.1 W START: 1988 SEPTEMBER 13: 0 PST INTERVAL: 60 min END: 1989 APRIL 19 6: 0 PST
CURRENT VELOCITY (CM/S) ALONGSHORE(320) COMPONENT CROSS-SHORE COMPONENT PRINCIPAL AXIS KINETIC Min Max Mean SD Min Max Mean SD degT Mean V Mean U ENERGY N ------_._------Total -63.6 42.0 -9.5 14.4 -29.9 55.8 8.3 11 .5 290 -12.4 2.5 168.9 4685 1988 SEP -52.7 22.9 -12.4 14.2 -19.6 40.7 11.6 11 .7 289 -16.6 3.6 169.2 707 OCT -63.6 32.0 -10.7 14.6 -19.8 51.7 7.3 12.4 286 -13.0 0.1 183.2 744 NOV -54.3 13.0 -15.7 12. 1 -15.8 55.8 10. 1 9.7 290 -18.7 1.0 120.7 720 DEC -38.0 32.7 -3.4 12.7 -16.4 37.8 7.0 10.4 289 -6.5 4.3 134.8 744 1989 JAN -43.0 18.1 -14.0 11 .8 -18.6 44.2 10.6 10.2 297 -17.0 4.5 121 . 1 744 FEB -35.3 42.0 -0.3 14.5 -29.9 40.7 4.8 12.9 282 -3.2 3.6 188.4 672 MAR -44.2 19.8 -9.7 13.4 -22.1 34.2 5.2 10.5 294 -11. 0 0.5 145.0 354 APR I I-' \0 I
Figure 7. Example of monthly statistical analysis performed on current meter record. Here, currents are separated into alongshore (toward 320 T) and cross - shore components. Principal axes of flow orientation are also presented. N is the number of samples. -20-
2. A detailed study of all satellite thermal imagery collected off the west coast from 1984 to 1990 has revealed several aspects of the shelf-break circulation that may be important to the alongshore transport of nutrients and zooplankton biomass. Work conducted with Gordon staples of the University of British Columbia indicates that intense localized upwelling takes place in the vicinity of the Scott Islands and west of Brooks Peninsula each summer. Cold, high density water upwells to the surface in these locations where it then merges with the southward flowing shelf-break current. Each event lasts several weeks whereupon the upwelling appears to weaken and the cold core of the shelf-break current retreats rapidly northward. Preliminary analysis suggests that the Cape Scott and Brooks Peninsula are regions where nutrient-rich upwelled water from depths up to 400 m penetrates directly into the surface layer. This water mixes with the ambient water and is then carried southward by the shelf-break current. It is these events which give rise to the marked cold core of the current during the summer. Nutrients and phytoplankton growth in the current would lead to increased zooplankton growth. Zooplankton are then transported longshore toward the La Perouse region. The event-like nature of the localized upwelling processes means that there are times when the transport mechanism breaks down and other sources of nutrients, such as upwelling through Juan de Fuca Canyon and local upwelling over the shelf, are needed to maintain the high biological productivity.
3. I have begun an analysis of the temporal variab~lity of the Vancouver Island Coastal Current based on moorings in the La Perouse Bank region and mooring E01 deployed off Estevan Point in 1988 and 1989. Specifically, we want to determine how strongly changes in flow off Estevan Point are coupled to other current records as a function of frequency. Preliminary results for April 23 to August 16, 1989 indicate that the Vancouver Island Coastal Current off Estevan Point actually strengthened during the upwelling event, perhaps due to a geostrophic response to enhanced upwelling and a resultant intensification of the gradient between the coast and the mid-shelf region. Observations further indicate that there is little shear in the top 15 to 35 m of the water column but considerable shear between 35 and 75 m depth. Observations also show that the current at E01C (a more inshore mooring than E01) has a stronger westerly component than at 15 m depth at E01, suggesting deflection by the cape. -21-
4. Inertial oscillations observed near the west coast of Vancouver Island have been analyzed in conjunction with Professor Pijush Kundu of Nova University in Florida. Results show that strong near-inertial current events in the upper layer are connected directly to onshore propagating storms but that near-bottom events are not linked to these frontal systems and must therefore originate offshore. R.E. Thomson -22-
3.1.2 Drifter Studies with a Tidal Model for the Southwest Coast of Vancouver Island
Freeland (1988) has hypothesized that salmon residency at the commercial fishing grounds around Swiftsure, Amphitrite, and La perouse Banks may be due not only to plentiful nutrients, but also to trapping by topographic eddies. He estimated that salmon trying to maintain their position expend energy 15 times more rapidly when no eddy is present than when an eddy is present. In order to test this hypothesis further, the barotropic tidal, and tidal residual currents calculated with a finite element model of the southwest coast of Vancouver Island were combined with Lagrangian particle tracking techniques to follow drifters deployed in the swiftsure Eddy. The residual tidal velocities calculated by Foreman and Walters (1990) are shown in Figure 8. Clockwise eddies are evident around swiftsure, Amphitrite, and to a lesser degree, the southern portion of La Perouse Bank. A counterclockwise eddy to the northwest of Cape Flattery and outflow along the Juan de Fuca Canyon can also be seen. Based on Figure 8, the Swiftsure Eddy was defined to be centered at (480 33.94', 1240 59.265'), have a radius of 5.67 km (approximately 2.5 times the arrow spacing), and have maximum velocities of approximately 7 cm/s. As the tidal currents in this region can be as large as 85 cm/s, it is not clear that the eddy is sufficiently strong to trap a particle. The first numerical experiment included barotropic velocities for the tidal constituents Q1, 01, P1, K1, N2, M2' 82' and K2. One hundred drifters were randomly dlstrlbuted in the circle defining the eddy. As all these constituent velocities have local maxima over swiftsure Bank, particles placed initially on the bank can be expected to disperse because excursions away from the bank will encounter velocities that are too small to guarantee a return. This dispersion was seen. The average retention time (last time at which a particle was inside the eddy circle) was found to be 24.2 days. In the next experiment, the velocities in Figure 8 were added to the previous tidal flows. The retention time now dropped significantly to 2.0 days, indicating that the residual velocities actually increase dispersion from the eddy region. The reason for this somewhat surprising result is that the eddy size is too small with respect to the distance travelled by a particle during a constituent cycle. The major semi-axes of the M2 and K1 current ellipses are 28.7 cm/s and 27.1 cm/s at the center of the swiftsure Eddy. Therefore, a particle under the sole influence of the M2 (K1) constituent over half a cycle will move 4.08 km (7.43 -23-
.. \,' .. , , 4
......
~ 4.0cm/s
......
, ,• ,
Barotrooic tidal residual velocities
Figure 8. Residual (time-averaged) currents generated by the main barotropic tidal current constituents off the southwest coast of Vancouver Island. -24- km). Depending on its initial position, a particle could thus go well outside the eddy region in twelve hours. Furthermore, as seen in Figure 8 the residual flow field beyond the eddy is quite complicated and could easily divert the return of that particle. Fish are obviously not passive particles. They can swim to remain in, or move to, a specific position. The question then arises, how much swimming would a simple fish require to remain in the eddy. In order to simplify this problem, we assume that fish only swim when their position from the center of the eddy is greater than 5.67 km. We also assume that at these times, fish swim at the rate of 208 cm/s (Freeland, 1988) toward the eddy center and stop when they reach the outer boundary of the eddy. The parameter e is set to 1.0 when a fish is farther than 6.17 km from the eddy center and it decreases linearly to zero as the proximity to the eddy boundary also decreases to zero (This gradual increase in swimming speed is necessary to avoid problems in the Lagrangian calculations that arise from discontinuities in the velocity field). In the first simple fish experiment, the velocity field was comprised of eight tidal constituents but no residual currents. As before, 100 fish were randomly placed inside the circle defining the eddy and their positions were calculated over 50 days. The maximum distance that any fish travelled from the eddy center was 13.81 km and all fish were able to get inside the eddy circle at some time during any three day period. In addition, the average swimming time was 19.2 days and the average speed when swimming was 8.67 cm/s. Freeland (1988) reports that juvenile salmon actually swim continuously at a speed of 1 body length per second, but divide their time between foraging activity and directed swimming. If we assume that the purpose of this directed swimming is to maintain a position in regions such as the swiftsure Eddy, then the previous calculations suggest that a 20 cm fish would spend 38% of its time in directed swimming. Furthermore, the fact that the average speed is much less than 20 cm/s suggests that much of this swimming is in the 0.5 km annulus just outside the defined eddy boundary and might be combined with swimming for the purpose of feeding. As only a component of 8.67 cm/s (on average)" need be directed toward the center of the eddy, a balance of up to 18.02 cm/s could be used for foraging in a perpendicular direction. When the residual flow field is also included in the calculations, the average swimming time increases to 20.3 days and the average speed when swimming increases to 8.96 cm/s. So at least for this simple fish, the presence of the eddy does not seem to offer any energy advantage. An obvious drawback of the preceding analysis is the fact that all tidal currents are assumed to be barotropic. Since -25- there are strong baroclinic features associated with currents observed in this region, the preceding retention and swimming calculations may change dramatically when the tidal model is improved to three dimensions. Indeed, the residual eddy around swiftsure Bank may have a vertical component that strongly affects its retention characteristics. The swimming strategy assumed here could obviously be enhanced and it is conceivable that a smarter fish might make better use of the eddy circulation. It may also be that smart fish simply hide behind Swiftsure Bank, much the same as we might hide behind a hill for protection from a wind, when tidal currents would otherwise tend to push them away. Hopefully, future 3D studies will shed further light on these questions.
M. Foreman -26-
3.1.3 Shelf Current Measurements During 1989
Shallow current meter moorings were maintained at two sites (E01 and E01C) near Estevan Point from April 15 to August 27, 1989. In order to measure the flow in the wave regime close to the ocean surface, Inter-Ocean S4 electromagnetic current meters were used at the shallowest (15 m) depth at each site. A single Aanderaa RCM4 was deployed at 35 m depth at site E01 (see Figure 6b). The daily averaged (tides removed) currents for each meter are presented in Figure 9. The strong northwesterly flow at all instruments is characteristic of the buoyancy-driven Vancouver Island Coastal Current. Short wind-induced reversals do occur but through much of the summer the inner shelf current is poleward counter to the prevailing northwest winds. Speeds of over 50 cm/s are not uncommon. The observations at E01 indicate that there is little shear between the flow at 15 and 35 m depth. The more ponounced westerly flow at E01C relative to E01 arises from greater deflection of the flow by the local bathymetry (E01C is closer to shore than E01). Loran-C surface drifters deployed on the shelf in the vicinity of E01 during early June (Day 154-159) yielded predominantly northwesterly flow similar to that measured by the current meters. In contrast, simUltaneous drifter tracks over the outer shelf and slope moved rapidly to the southeast in response to the wind-forced shelf-break current centered over the 200 m depth contour. Drifters deployed over the mid-shelf region between the two dominant inner and outer flow regimes showed confused and variable flow. The drifter and current records are consistent with our picture of the summer circulation over the shelf given by Figure lb.
Mike Woodward Rick Thomson ( o Stn EOle Depth OOl5m Moving avg filt width=l day. sampled at 8 hrs. lJ)
(f) "EO U
-0 lJ) I o Stn EOl_ Depth 0015m Moving avg filter=l day. sampled at 8 hrs. lJ)
I IV o lJ) -..J I I
o Stn EOl_ Depth 0035m Moving avg filter width=l day. sampled at 8 hr lJ)
o ~+I~~~--~--~--~~~c---.----'---'----~~ 113 125 137 149
Figure 9. Daily averaged current vectors for mooring sites immediately seaward of Estevan Point in approximately 90 m of water for the period April 23 (Day 113) toe August 21 (Day 233), 1990. North is upward and east is to the right in the figure. Records are subsampled to 8 hour values for plotting purposes. -28-
3.1.4 A Comparison of Currents, Wind stress and Sea Level Fluctuations off the Pacific Coast of Vancouver Island, British Columbia
Current velocities at depths of 50, 100 and 150 metres (m) over La Perouse Bank and off Estevan Point have been compared with adjusted sea levels at Bamfield. The two are highly correlated. The linear correlation coefficients for Bamfield sea level heights versus alongshore current velocities are: La Perouse 50m: 0.902 100m: 0.902 150m: 0.792 Estevan Point 50m: 0.911 100m: 0.877 150m: 0.814 The variability of sea level and current velocity are approximately in phase, with a slight tendency for the sea level to lead currents, by about 1/2 day. The wind stress, as obtained from the upwelling indices, was moderately correlated with the currents (linear correlation coefficient of 0.693). The highest coefficients were obtained for currents lagging the wind stress by 1- 1 1/2 days, suggesting that it takes this much time for the currents to respond to the winds. The relationship obtained between the sea level at Bamfield/Tofino and currents at La Perouse Bank and off Estevan Point (Figure 10) is sufficiently strong and therefore it has been employed to create a set of "synthesized or hindcasted" currents for these areas for the period 1963-1987.
s. Tabata H. Waddington D. Ramsden -29-
o o CO 1
x w Q 0 Z 0 "" ~ E u o 0 ...... "" CURRENTS (MEASUREMENT DEPTH) 50m ...... 100m-- Fi~re 10. Comparison of Bakun Upwelling Index (480 N, 1250 W), barometrically adjusted sea level at Tofino, and low - pass filtered lonshore component of the measured currents at depths of 50 and 100 m near Estavan Point for May - September 1980. -30- 3.2 BIOLOGICAL OCEANOGRAPHY PROGRAM 3.2.1 Biological Oceanography Program Rationale and Sampling strategy The goals of the Biological oceanography component of the La Perouse Project are to describe and quantify seasonal and interannual variability in plankton biomass and community composition for the southern Vancouver Island outer coast, and to learn whether lower trophic level variability is transmitted up the food chain to commercially exploited stocks. Although the continental shelf and slope zone off Vancouver Island is relatively narrow, distinct oceanographic regions (based on water properties, plankton biomass and composition, bathymetry, and current pattern) have been identified in previous studies. The present sampling scheme for the LPBP is based on multiple sampling within the regions shown in Figure 2b and described below: Region A (outer bank edge, shelf break and slope). Currents are primarily parallel to the bottom contours and toward the SE in summer, NW in winter. water properties are relatively offshore in character (high salinity, low surface nutrients and phytoplankton). Regions Band D (inner banks and basin off Barkley Sound). Currents and water properties are strongly influenced by the discharge from Juan de Fuca Strait (averaging alongshore to the NW year-round but probably with considerable and variable cross-shelf component). Salinity is relatively low in the upper iayer, nutrients and phytoplankton concentrations are often extremely high. Region C (Shelf region south of the major banks; Juan de Fuca canyon and gyre system). Currents show a strong cyclonic curvature. Upwelling of deep water along the canyon axis is very intense through late spring and summer. This region appears to be a major source for deep water entry onto the shelf. Nutrients and phytoplankton concentration are often high. The present sampling grid (Figure 2b) includes 3 stations in Region C, 4 stations in Region A, and 8 in Regions Band D (several of the latter are sited at reported herring aggregations). The stations are sampled opportunistically during lOS and PBS research cruises operating in the vicinity; routine samples consist of vertical or oblique net hauls (0.23 mm mesh) integrating zooplankton concentration over the entire water column above 250 m. The zooplankton -31- samples are analyzed under contract (1985 and 1986 samples by Edward Anderson Marine Sciences, 1987 samples by Aquametrix, 1988 and 1989 samples by Sy-Tech Research) for total biomass, species composition, and size spectrum. Full data records are archived by Ocean Ecology Division, summary data lists (abundance of major taxa, biomass by major size category) are provided to PBS scientists involved with LPBP. The use of several stations within each region allows an estimate (and averaging out) of local patchiness. Zooplankton Species Composition in the La Perouse Study Area. To what extent do within-time-period sample groupings based on species composition match these hydrographic regions? For each of the twenty-six time periods (cruises) sampled to date, I used a mUltivariate cluster analysis to identify samples with similar species dominance hierarchy. within each time period there were usually three (occasionally two or four) compositionally distinct sub- groups. Figure 11 shows the frequency of membership in the four identifiable cluster "types" by each of the La Perouse sample locations. Overall cluster membership corresponded well with region membership, although a few sites (notably A1, B8 and C3) showed frequent crossovers to adjoining regions. The "average" seasonal cycle of species composition in each of the regions is shown in Figure 12. Region A is dominated in spring and early summer by chaetognaths and by large Subarctic Pacific copepods, mostly of the genus Neocalanus. In two out of the five years sampled, this region had high biomass of offshore gelatinous zooplankton species (salps, siphonophores and doliolids) in late summer and autumn. Region B is dominated in spring and early summer by the smaller copepods Cal anus and Pseudocalanus and by hydromedusae. Total zooplankton biomass is on average lowest in this region. It peaks late spring to early summer, then declines later in the year. The euphausiids Euphausia pacifica and Thysanoessa spinifera make up much of the relatively low late summer zooplankton standing stock. Region C has the highest average zooplankton biomass and is intermediate in species composition between Regions A and B. The most striking feature of the multi-year average seasonal cycle is a late summer/early autumn maximum in euphausiid biomass; much of this peak is due to relatively high euphausiid abundances observed in 1988 and 1989. The seasonal cycle for the copepod species was more consistent between years. Calanus biomass peaked June-July in Region C (vs. April-May in the more nearshore environment represented -32- Cluster membership by site 1985-89 100 % 75 0 c o Outlier c u ~Gyre r 50 e • Banks n c Iii!IOffshore e 25 a A A A A B B B B B B B C C C S D D 4 3 2 1 3 2 6 7 518 3 1 2 121 & 4 Figure 11. Overall frequency of membership in "offshore", "banks", "gyre", and "outlier" cluster groups for each of the La Perouse Project zooplankton sampling stations. Two cluster analysis methods (average linkage and sum of squares) were applied. -33- 1985-1989 Average: Region "A" 10 8 Estimated OW 6 (g/m2) 4 2 o Feb April May-June July August Oct-Nov 1985-1989 Average: Region "8" 10 8 Estimated OW 6 (g/m2) 4 2 o ~zggjj Feb April May-June July August Oct-Nov 1985-1989 Average: Region "e" 10 8 Estimated OW 6 (g/m2) 4 2 o Feb April May-June July August Oct-Nov Time Period .- Remainder ~ Ctenophores ~ Medusae m Solps III Choetognaths DIID Neocalanus IIIIm Metridia (i Pseudocol. lit Calonus Iii Euphausiids Figure 12. Multi-year average sea$onal cycle of zooplankton biomass in the La Perouse study area, broken down by region and dominant zooplankton taxa. Shading codes for the various taxa are shown at the base of the Figure. -34- by Region B and July-August in the more offshore environment of Region A) • D.L. Mackas -35- 3.2.2 EI Nino Update (5 March 1990) Background In the "La Perouse Project First Annual Progress Report 1985" (March 1986), the second sentence reads "It is no coincidence that the program began shortly after relaxation of the anomalous mid-latitude oceanic conditions that accompanied the major EI Nino-southern Oscillation (ENSO) event of 1982/83". The first sentence of the second paragraph read "The maximum anticipated life of this multidisciplinary study is 10 years, which should encompass one (and possibly 2) ENSO events". In 1986-87 a moderate EN SO event took place with a weak (about 1.50 C) warm anomaly at British Columbia lighthouse stations, but no obvious biological indications that could be related to the ENSO with any confidence. In the last 6-8 months warm conditions have been reported from local lighthouses and in parts of the subarctic North Pacific. In the last few months, some but not all forecasts suggest an ENSO warm event in 1990, and Pacific tropical atmospheric and oceanic conditions have exhibited many of the precursors of an ENSO event. It seems timely that we review the present status of a possible ENSO in 1990 so that we can design and augment our sampling plans for the next year. Clearly, if a major ENSO occurs, we must be prepared to document its occurrence at our latitudes and to obtain sufficient biological observations to resolve its impact on the marine foodchain. Otherwise, we will have failed to meet a prime objective of the La Perouse Project. Anomalies in British Columbia Waters An EN SO event can affect local oceanographic conditions in two ways. (i) By propagation/advection along the Pacific coastlines of the Americas from the equator to high latitudes, of warm temperatures and increased coastal sea levels. The mechanism is believed (by some) to be a coastal Kelvin wave propagating from the equator. Observations, especially of sea level anomalies, have included documentation of this sequence of events. We would expect such events to reach our latitude several months after they are observed at the equator. (ii) By atmospheric "teleconnection" between pressure and circulation patterns in the Pacific tropics and mid latitudes. Intensification of the Aleutian Low is the usual teleconnection considered to affect our region. There is assumed to be no appreciable time lag (less than several months). In our region intensification of the Aleutian Low should cause warmer, wetter and stormier winters, a delayed spring transition, a cooler wetter -36- summer, and less intense coastal upwelling due to less frequent northwesterly winds in summer. Many of these conditions occurred in 1982-83. We have other periods of anomalous conditions that cannot be associated with ENSO events, but may affect the marine foodchain. In the top panel of Figure 13, we show the monthly average sea surface temperature (SST) anomaly for the last 10 years at Paita at the northern end of the Peru coast (without running average). The massive anomaly associated with the 1982-83 ENSO and a lesser anomaly associated with the 1986-87 ENSO are clearly evident. In the lower panel, we plot the same variable from the Amphitrite lighthouse on the west coast of Vancouver Island. The 1982-83 ENSO signal is clearly present, as is a weaker anomaly for the 1986-87 event. A strong sustained warm event in 1981 and shorter cold events in 1985 and 1989 do not correlate with Paita temperatures, except for the 1989 cold spike which is inversely correlated. The last 10 months of warm temperatures at Amphitrite do not reflect a similar signal at Paita, and may have ended according to the February reading. What is ENSO? During most years the equatorial Pacific is subject to easterly (i.e. blowing to the west) trade winds (Fig. 11.28 in Gill, 1982). The westward-flowing South Equatorial Current piles up warm surface water in the western equatorial Pacific raising the sea level about 50cm above that at the Galapagos Islands off Equador (Fig. 11.17a, ibid). In response the Equatorial Undercurrent returns colder water from below the thermocline to the east where it shallows and reaches the sea surface to replace the warm surface water that has been forced to the west (Fig. 11.17b, ibid). The normal cold nutrient-rich surface waters off Equador and Peru are present during these conditions. If for a variety of reasons, not all understood, the easterly trade winds stop blowing, the warm surface water piled up in the western equatorial Pacific flows to the east, pushing the shallow thermocline down, and replacing the cold waters off Equador and Peru with warm nutrient-poor waters often down to 200 m depth. The eastward flow of warm surface waters occurs not as a smooth flow but as a series of eastward propagating "first mode baroclinic Kelvin waves" of several week period. When they reach the Galapagos, they apparently propagate, or force waves of similar periods, north and south along the Americas' coastlines. This warm event often peaks off Peru around Christmas, hence the name EI Ni~o (loosely translated, the "Christ child"). Because of this sequence of events, two large scale atmospheric parameters provide reliable indication, though not prediction, of the occurrence of an EI Nino. The first - " '~'": .. '---,-'-/:---:':" '-~- . - :.' . '.':'~.- -;-:-. '_-.' ·-r .'.-" -37- Paita. Peru ..... III E o c: « -3 80 81 82 83 84 85 86 87 88 89 90 Year Amphitrite Point 3 U ~ .....>- III E 0 c: « -2 -3 89 90 80 81 82 83 84 I 85 86 87 88 Year Figure 13. Anomaly from the monthly average sea surface temperature for the period 1980-90, for Paita, Peru (upper panel) and for Amphitrite Point, Vancouver Island (lower panel) . -38- is the Southern Oscillation Index, a standardized sea level atmospheric pressure difference (Tahati-Darwin, Australia). When it is negative, there is a west-to-east pressure gradient in the western tropical Pacific that opposes the trade winds. The second is standardized 850 mb easterly winds in the latitude belt 5 0 N to 50 S for 175-1400 W, i.e. a measure of the trade wind strength in the tropical mid Pacific Ocean. A negative value indicates a relaxation of the easterly trades and possibly even westerly winds near the equator. Present Conditions Since 1982-83 ENSO research and prediction has been a growth industry, especially in the US. Most of the active scientists have agreed to present their predictions and observations on an electronic bulletin board OMNET's ENSO.INFO to provide timely discussion and prediction by the community. Typically there are several entries per month, but in February there were 41 entries as interest in a possible warm event in 1990 heated up. We have tried to summarize the information here. First, about 5-6 groups have developed ENSO forecast models. Several of these, the more statistical ones, have forecast a warm event for 1990. The others tend to forecast a small negative SOl for the next few months, but smaller than 1 standard deviation, not considered statistically reliable. There is some discussion that at least one of the models uses only winds to force the model and not sea surface temperature, hence missing valuable information. The SOl has just become negative but small over the last several months. A provisional value for February was posted today. It is large (-2.5), but other isolated monthly anomalies that size have occurred that have not resulted in EI Nino events. A large low pressure storm persisted near Tahiti for much of the month (February) which may have caused the low value for Tahiti. The 850 mb easterly wind anomaly has become negative but small over the last few months, again the right sign but not large enough to be considered clearly significant. The trades have slackened at other locations along the equator, and in January the 28.50 C isotherm moved to the east across the dateline. Sea level height is tending high in the eastern tropical Pacific, and temperature anomalies at a depth of 150 mare positive in the central and eastern equatorial Pacific (exceeding 2 0 C at 140 W). The anomal¥ as of ~id Feb~uary was +2.80 C at 100 m near 150 m, "cons1stent'w1th a f1rst baroclinic mode Kelvin wave" and "similar to that analyzed in Nov-Dec of 1986, though perhaps not yet quite as strong" (Nevelle smith, BMRC, Australia). Also according to David Enfield, NOAA Miami (14 February), 1990 is "right at the median return interval (7-8 years) for strong EI Ninos". A -39- strong EI Nino off Peru does not necessarily translate into a strong signal off British Columbia. Moreover, no one is willing to forecast the strength of an EI Nino in 1990, only that there is good evidence for a warm event in 1990. Observations in the period April-June are considered essential to establish whether we are entering an ENSO event, with peak warming off Peru expected in December 1990. If the EI Nino materializes and is moderate to strong, then its' expected timing off Peru and off the BC coast are of considerable importance to the La perouse project. In Fig. 14 we have plotted SSTs (not anomalies) for the last two ENSO events and for the mean annual cycle: at Paita, Peru (upper panel) and at Amphitrite lighthouse, Vancouver Island (lower panel). The Paita anomaly peaked in February March in 1987 and in May .in 1983. The Amphitrite anomaly peaked in February in 1987 and in March in 1983, the lack of a time lag supporting the teleconnection hypothesis. The important point to make here is that if we are entering an ENSO event, we do not expect the SST anomaly off our coast to exceed l oC until late Autumn 1990, with a peak in February-March 1991, about 1 year from now. Thus, we recommend that our strategy should be to monitor conditions closely until the end of June, then to decide whether to plan extra observations for the winter-spring 1991 period. Winter-hatching ground and shell-fish species, and salmon that first enter marine phases in 1991, ought to be the most affected and hence most closely monitored. K. L. Denman H. J. Freeland Editor's Note: The May 1, 1990 report from the Pacific Ocean Watch Group (chairperson Howard Freeland) is that the Southern Oscillation Index has returned to zero, indicating that EI Nino conditions are not likely to develop in the Pacific Ocean in the winter of 1990 to 1991. Several more months are needed to fully determine if this is a valid interpretation. -40- 30 Paita SSTs ---Means· ...... -1982-83 ------1986-87 -·_·-1990-91 r - - \ I \ 25 I \ I \ I \ I \ I \ I \ I \ I \ I \ \ \ \ 1 __ J \ \ I \ . I \ ... , \ "" I ... , \ "" I ... . '.1 '// ... ,. .... " I '" , ...... ' I '" , / ..... , '" "" '\ , ,' • 15 J F M A M J J A SON 0 J F M A M J J A SON 0 20 Amphitrite Point SSTs ---Means· ··········-1982-83 ------1986-87 -·_·-1990-91 15 //,~. . "'" ...... /.. . .. / .-- ...... " '.. / I" .' " / ,. / I .. ' ,. I .. ". ,. ..\ / '" / \ .. / .. \ 10 ..\ , . '\, ... ,,' ;'."...... / 5 J F M A M J J A SON 0 J F M A M J J A SON 0 Figure 14. Monthly average sea surface temperatures: long term means (solid line), 1982-83 ENSO (dotted line), 1986-87 ENSO (dashed line), and the current situation (dash-dot line); for Paita, Peru (upper panel), and for Amphitrite Point (lower panel). Note that we are presently about 1 year away from expected maximum warm anomalies if a warm event develops in 1990. -41- 3.3 FISHERIES OCEANOGRAPHY PROGRAM 3.3.1 Pacific Hake Distribution and Recruitment Pacific hake (Merluccius productus) is the most abundant species in waters off the west coast of Canada and is a major component of the groundfish fishery. The offshore stock is migratory and, after spawning off California and Mexico during the winter, moves northward to feed during the summer from northern California to Queen Charlotte Sound. Schools of adult hake first appear off Vancouver Island in late May and remain until late November. The southward migration may be triggered by the shift of the wind direction in the fall and the appearance of the Davidson Current. The objectives of this study are: (1) to determine the distribution and relative abundance of Pacific hake in Canadian waters on an annual basis; (2) to examine hake distribution in relation to oceanographic and biological features; (3) to determine biotic and abiotic factors controlling year-class success in hake; and (4) to determine the impact of Pacific hake and other predators on the abundance of Pacific herring (with D. Ware and R. Tanasichuk) . Research on the distribution, abundance and biology of the hake stock has been conducted annually since 1977. The most recent survey was conducted in August 1989. Results indicate that hake were distributed from the Canada-U.S. border to Triangle Island at the northern tip of Vancouver Island (Figure 15) and into Queen Charlotte Sound. North of La Perouse Bank, hake were found as small, discrete schools along the 150-200 m isobath. As in past years, the majority of the stock was located in the vicinity of La Perouse Bank in association with the 150m isobath. In 1989, heavy concentrations of hake were found in and adjacent to, Barkley Sound (Figure 15). Fishermen also reported that there was a considerable body of hake in Strait of Juan Fuca. Unfortunately the 1989 survey did not extend into this area. Total reported catches have ranged from 65,000 t in 1969 to 39,000 t in 1976. Prior to 1975, the USSR caught the major percentage of hake in the Canadian zone. After 1977 the commercial fishery was divided into the foreign, joint venture, and domestic fisheries. Since 1977, total reported catches of hake have been increasing steadily to 97,845 t in 1989. participating countries in 1989 were Japan, Poland, and the USSR. A small domestic fishery lands hake to U.S. markets. In addition to the 1989 Canadian hydroacoustic survey, U.S. triennial hydroacoustic and bottom trawl surveys were .... ··iz9· 1240 ·",3" :1 tI" ;j .... ' . .... :1 '. ~'" J ...... U "1 "~ ...« "".. 50' 5cr I·. r -~." '.eo:, ' ... ~...... ' A.,.. .-~ ...... 'CO.m ...... ' ~~". ••.••.... .° 0 20pm ~ ..... I ~ N " ~' .. I ZOOO '" ' ..~ 49" I ',. "'\ .'.". . ~~ '. • '1"9.~~<- ... "~.,'.;... ' I .. ~ ,~.. . ~I ~ : .' ~:~ ...... \ ..... ".. .. _0: us .!\ , wATERS 8 '. 129" Ize" 1278 )26 Figure 15. Coastwide distribution of hake based on the 1989 hake/ herring echogram survey. -43- conducted coastwide. The u.s. survey found 1.2 million mt of hake coastwide. The U.S. hydroacoustic estimates for the Canadian zone are the lowest on record at 80,000 mt, yet the bottom component of the stock as estimated from the bottom trawl survey were the highest recorded (23,000 mt). The U.S. survey extended to 50 degrees north. Fifty thousand mt of the 80,000 mt total were found north of 49 degrees, which was the northern limit of the Canadian hydroacoustic survey. In the comparable area south of 49 degrees the Canadian estimate was 54,000 mt using a comparable target strength value. Both surveys failed this year to assess the fish in Barkley Sound and Juan de Fuca strait and since u.s. tracklines are broader than Canadian ones over the La Perouse bank region it is felt that a considerable portion of the stock was not assessed. The proportion of the stock available to the Canadian fishery is in good condition as the Canadian fishery continues to be supported by a series of strong year classes, particularly the 1984 and 1980 year-classes. However, overall the stock is entering a period of decreased abundance as a result of poor recruitment following the strong 1984 year-class. A detailed examination of the decreasing size-at-age of hake discussed in previous reports was conducted this past year. We found that length-dependant migration rates of hake result in the Canadian fishery selectively removing the large hake of any age, thereby annually reducing mean lengths-at-age. Apart from the general decline, oceanographic factors satisfactorily explain most interannual variability in mean lengths-at-age and apparently also affect the summer biomass of hake in Canadian waters. Mean lengths-at-age in Canadian waters were generally smaller in years of above normal sea level height and temperature and below normal salinity. In years of higher than normal sea level, such as during El Nino Southern Oscillation (ENSO) events, more smaller fish arriving off Vancouver Island would tend to decrease mean lengths-at-age there. During 1989, the focus of work on the biotic and abiotic factors affecting the distribution of hake has been the implementation of a Geographic Information System (GIS) to analyze the numerous and varied data sources. We have been successful in importing fishery, hydroacoustic, salinity, temperature and geostrophic current data as well as sea surface temperature satellite images from August 1987 and August 1989 windows. During the next year analysis of the relationships among the various factors will be conducted. M.W. Saunders G.A. McFarlane -44- 3.3.2 Herring Mortality. Distribution and Recruitment An exploratory analysis of the existing oceanographic and fisheries data for the 1960-81 period (Ware and McFarlane 1986) at the outset of this project indicated that year class strength in the lower west coast of Vancouver Island herring stock is negatively correlated with the biomass of Pacific hake, and with the annual sea surface temperature. Recently, these findings were corroborated by a more extensive analysis of herring recruitment and growth using the entire historical data base, which was extended back to the 1930's (Ware 1990). Guided by these relationships, a program was designed to determine if the mortality of pre-recruit and adult herring was related to the spatial and temporal overlap in the herring, and herring predator distributions on the continental shelf, and by the abundance of alternative prey during the upwelling season (May-October). A mUltispecies predator-prey model was developed this year using 5 years of diet information, collected during the project. In the current configuration of the model, euphausiids and herring are the principal prey, while hake, dogfish and chinook salmon are the dominant predators. preliminary results indicate that at recent stock levels hake, herring and dogfish consume some 360,000 tonnes of euphausiids in the La Perouse bank area between mid-June and mid-October. In addition, hake, dogfish and chinook eat 35,000 tonnes of herring, and dogfish consume 31,000 tonnes of hake. An assemblage of subordinate predators (i.e. coho salmon, Pacific cod, sablefish, lingcod and halibut) eat an additional 25,000 tonnes of herring annually. with these figures, we can now account for all of the estimated average, annual natural mortality of the lower west coast of Vancouver Island herring stock. The output of the mUltispecies predator-prey model supports the exploratory data analysis that Pacific hake is the dominant predator of herring, and that interannual variations in the intensity of predation are large enough to affect recruitment. The model also emphasizes the key role euphausiids play in supporting the resident and migratory stocks of fish that feed in this very fertile region during the upwelling season. Distribution: Between August 13-22, 1989 a bottom and mid water trawl survey of the herring and groundfish stocks in the La Perouse study area was conducted aboard the F.V. "Ocean King". The general distribution pattern was typical for August, except that very few herring were encountered this year near the outer edge of the continental shelf. The highest concentrations of herring were in subareas 6 and 9, whereas the hake biomass was most concentrated in subareas 4 and 10 (Figure 16). 49°00' , '--, / ,/ ,, ..... , IOOOm "- , 14.1 '-, /' \ ..... , \ , 13.1 ,I 48°30' I FISHING SUBAREAS I / "\ 01::00 I. BARKLEY SOUND I _-- \ U1 2.FIRING RANGE I 3. S W CORNER 4. POTHOLES 10.1 5.12 MILE BANK '- ~-"\ f'\ 6.40 MILE BANK (_I \.. \ \ / , \ ) \ 7. FINGER BANK \ J ,/"1 rJ (..J I ,.... II/ 8. BOTTLENECK I I , -J'.... 9. SWIFTSURE BANK I .... .; "' ..J ""...... __ --J',- \ '" , " 10. EDDY ..., .... 1 I ,f'.J II. WEST BANK / \ 12.1 ./ / .....1. " 12. SOUTH SLOPE ' "\ I " \ \ I 13.CENTRAL SLOPE ..... j ---"'",... 200m 200m 14. NORTH SLOPE ./ 48°00' ..... "\ I I \ LI______~------_,------~(~------~--~~--~/----~------~ ~~--~------~~ 1~6°00' 125°00' Figure 16. Major~ cbncentrations 6f herring (dense shading) and hake (circled areas) encountered by F/V Ocean King during August 13-22/89. -46- Hake Impact: The daily food ration of hake in August 1989 (2.9% body wt/d) was considerably above the 6-yr average (1.5% body wt/d)i however, the amount of herring in the daily ration (0.06 % of the body wt/d) was the same as the 6-yr mean. It is significant to note that the interannual variability in the amount of herring in the August ration of hake (cv=72%) is of the same order as the coefficient of variation in herring recruitment (cv=66%). Length measurements of intact herring found in hake stomachs indicate the following distribution of age-groups eaten in August 1989. The results for August 1988 are shown for comparison: % Occurrence 1988 1989 Age 0+ 89 53 Age 1+ 3 17 Age 2+ 2 20 Adults 5 9 Recruitment Forecast: A secondary objective of the August trawl survey is to obtain a herring pre-recruit abundance index. This index has been derived and tested for 3 years, and the preliminary results are encouraging (Figure 17). The August 1989 survey suggests that 3-yr old herring should form 40% of spawning stock (by frequencYi or 29% of the biomass) in March 1990, which would make it an AVERAGE recruitment. Major activities for the 1990/91 season will focus on improving the multi-species predator-prey model so we can evaluate interannual variability in herring predation rates, and some possible explanations for the negative correlation between water temperatures and herring year-class strength. We will also begin looking at the long-term variability in herring weight-at-age and attempt to identify the importance of interannual variations in climate in the La Perouse bank area and stock size on herring growth rates. D.M. Ware R. W. Tanasichuk W. Shaw -47- 100 o 80 B S E 60 R V E 40 D 20 o o 20 40 60 80 100 FORECAST Figure 17. Relationship between Forecast and observed percentage of age 3 herring (by frequency) in the lower west coast of Vancouver Island herring spawning stock (1987-89). -48- 3.3.3 La Perouse Surface Living Macro- Zooplankton Although no work was done on La Perouse Bank per se, the documented barrier effect of the Vancouver Island Coastal Current (VCII) on the onshore movement of surface-living zooplankton was studied further north off the west coast of Vancouver Island. This barrier effect concentrates larger zooplankton, at least, in the Shelfbreak Current (SBC) on the seaward side of La Perouse and in the Juan de Fuca Gyre, and so understnading the process by which this is achieved is relevant to the La Perouse study as it in part determines the spatial pattern there of macrozooplankton abundance. In conjunction with R. Thomson, who collected the relevant oceanographic data, we determined the absolute abundance of crab megalopae in a continuous series of neuston tows along transects going from the VCII to the SBC. This was done from Line D to off Brooks Peninsula. The megalopae appear to be concentrated in an area of up-welling and/or seaward sUlface current movement of relatively low velocity (1-5 cm sec- ). The presence of the VCII seems to direct most of the up-welled water offshore, while because of the shallow dep'th of this portion of the shelf, no shoreward movement is possible beneath the VICCo The only opportunity for shoreward movement is thus when the VCII temporarily breaks down because of cessation in the surface outflow in Juan de Fuca Strait, usually associated with sustained, strong southerly winds. Shoreward movement could then occur because of onshore coriolis movement generated by these winds. The megalopae abundance data presented (Figures 18 to 19) should be interpreted in comparison with Thomson's oceanographic data. Glen Jamieson -49- Line G, June 1989 (before storm) Abundance (per 10 square meters) Depth (m) 1000~------~600 C. magister 500 100 -+- C. oregonensls ---*'""" Euphausllds ~ 400 10 Depth 300 1 200 0.1 100 0.01 0 0 10 20 30 40 50 60 Distance offshore (km) Line G, June 1989 (after storm) Abundance (per 10 square meters) Depth (m) 1000~------~1200 C. magister 1000 100 -+- C. oregonenala ---*'""" Euphauallda 800 10 ~ Depth 600 1 400 0.1 200 0.01L---~--~------~----~~~4-~--~~--~0 10 20 30 40 50 60 Distance offshore (km) Figure 18. Abundance of various macrozooplankton along the offshore transect at Estevan Point, British Columbia (see Figure 6b), before and after a storm. ... -",-."" .. ,-.-,;., -_ , .,. -50- Brooks Peninsula, June 1989 Abundance (per 10 square meters) Depth (m) 1000~------~1200 C. magister 1000 100 -+- C. oregonensls ""*- Euphausllds -e- Depth 800 10 600 1 400 0.1 200 O.01~~~4L------L-----~------~----~----~0 o 10 20 30 40 50 60 Distance offshore (km) Line E, June 1989 Abundance (per 10 square meters) Depth (m) 1000~------,600 C. magister 100 -+- C. oregonensla 500 ""*- Euphauallda 10 -e- 400 1 300 0.1 200 0.01 100 O.oo1L------~--~~~+---+-~~~~~~--~~~0 10 20 30 40 50 60 Distance offshore (km) Figure 19. Abundance of various macrozooplankton along the offshore transect Ca) at Brooks Peninsula, and b) at line E north of Tofino, British Columbia (see Figure 6b). -51- 3.3.4 Pacific Cod Recruitment The objective of this study is to explore how year-class success of Pacific cod (Gadus macrocephalus) is related to its reproductive biology. We will describe the spawning migrations, the gonad maturation cycle, determine the time of spawning and location of spawning grounds. At present, we have partial knowledge of these aspects of cod biology. In addition to being of fundamental importance to understanding reproduction,the information will allow us to plan larval cod surveys in the near future. In the past, fish larval surveys have not been able to find cod larvae. The research will involve comparing reproductive responses of Pacific cod to the same sets of physical oceanographic variables in two important fishery areas, La Perouse Bank and Hecate strait. The La Perouse Bank stock is the most southerly stock of Pacific cod of the northeast Pacific Ocean large enough to be the target of a fishery, while the Hecate strait stock is the most important cod stock for the west coast of Canada. The work was started in 1987 in Hecate strait, and in 1988 in the La Perouse Bank area, and will continue for a 5 year period. We suggest that the success of cod recruitment over the long run is partially dependent on reproductive adaptations of the parents, and that larval and juvenile survival is not independent of these adaptations. Consequently, a study of reproductive biology should produce insights into changes in year-class strength. Reproductive responses will be compared to year-class success determined with fishery catch data. Biological samples are being collected at sea in the commercial fishery, on research vessel cruises, and by sampling commercial vessels in port. We are examining oocyte size and gonad maturation rate, using histological techniques, and determining spawning timing and location, and also examining ovary weight and fecundity in relation to fish weight and age. Our hypothesis is that the higher temperatures of the water in the La Perouse area as compared to Hecate Strait, and the differences in ocean currents, will cause differences in the reproductive responses of the cod. During the course of our research in Hecate Strait, we discovered a statistical relationship between year-class strength of the stock of Pacific cod in Hecate strait and oceanographic processes there, using historical time series data. Increases in the strong currents flowing northward while the fish are in the larval and early juvenile stages decrease year class strength. We have also found that increases in the abundance of young herring (perhaps as prey) enhance year class strength, and that net recruitment maximizes at a spawning stock size of 4000 t representing -52- 1/5 the maximum biomass of spawners, estimated at a standardizing zero fishing effort level in our model. In the modelling of year class strength for the La Perouse area, we are looking at the historical data series of age 3 recruitment for the region by using linear and second order, mUltivariate curvilinear methods to examine the 24 years of data prior to 1980. Our five hypotheses are: 1) recruitment increases with increased Ekman convergence at the time of hatching (February); 2) recruitment is related to ambient temperature at the time of hatching (February) as a dome shaped curve with a peak between 6.50 and 7.0oC. 3) that there is a dome shaped curve relating recruitment to adult stock size; 4) that recruitment is positively related to the abundance of juvenile herring hatched in the same year as the cod brood (possibly because young herring were eat~n by young cod, consequently increasing their growth rate and, hence, predator escapement); 5) that the recruitment is positively related to the summer abundance of age 0 and age 1 herring one year prior to cod spawning (because when pre spawning cod feed well they could produce a stronger year class due to increased fecundity and egg quality). Preliminary results from statistical examination of the La Perouse stock suggest that (1) there is a critical stock size below which recruitment falls off; (2) a high abundance of herring is associated with increased recruitment; (3) intermediate to high levels of convergence are associated with increased recruitment; (4) the temperature optimum hypothesis seems supported. The factor having the strongest influence on recruitment seems to be Ekman convergence. The hypotheses are being examined more thoroughly for consistency in the time series. We are using a variety of statistical fittings that will allow the two and three factor models to be ranked by degree of variance explained. We will also test the best of the models to find which will predict the outstanding 1985 year-class. The data for the 1980s was not used in the statistical fitting, and so the 1985 event will provide an independent test. Based on macroscopic examination, we found that mature female Pacific cod go through five ovary development stages every year: early ripe, late ripe, running ripe, spent, and -53- resting. (Full macroscopic and microscopic descriptions of the stages are in Bowden et al. 1990). Oocytes from fish of each stage were also described microscopically. Two size groups of oocytes are usually present. All of the larger oocytes are vacuolated and have a smooth band around the nucleus. There is also a group of small oocytes that are non-vacuolated. The vacuolated oocytes undergo vitellogenesis (yolk deposition) by September, while the reserve group of oocytes remains undeveloped. In February, the oocytes are freed from the ovarian wall and become translucent as they become hydrated. The oocytes are then known as "ova". This stage seems to last for only a short period, perhaps less than a week. Only low numbers of fish are ever found in this state. After spawning, a few translucent ova remain in the ovary, while others are seen being resorbed. There are also collapsed, empty follicles visible, and reserve group oocytes. By measuring the diameters of oocytes we constructed histograms of oocyte size distributions. Early in the recovery stage following spawning, the distribution is unimodal with a size range of 20 to 110 microns. By August, just prior to vitellogenesis, the distribution is distinctly bi-modal, with the larger group of oocytes ranging from 180- 300 microns. By January, ju~t before spawning, some oocytes are as large as 800 microns. During this period, the group of small oocytes does not change its size distribution (Figure 20). At spawning in February or March, the ova are 1. 00 to 1. 02 mm. A. V. Tyler R. P. Foucher -54- Frequency 16 14 12 10 8 6 4 o 200 400 600 800 Diameter (microns) Figure 20. Oocyte frequency histogram in numbers of oocytes, from Pacific cod no. 33 sampled on February 5, 1988. Amphitrite Bank; maturity stage = late ripe. -55- 4. REFERENCES CITED AND/OR RECENT REFERENCES RELEVANT TO THE LA PEROUSE STUDY AREA Bowden, D.G., R.P. Foucher and A.V. Tyler. 1990. A guide to the Ovarian Histology of Pacific Cod. Can. Tech. Rep. Fish. Aquat. Sci. 1723. 44pp. Crawford, W.R. and R.E. Thomson. 1990. Physical oceanography of the western Canadian continental shelf. Cont. Shelf Res., in review. Denman, K.L. and M.R. Abbott, 1988. Time evolution of surface chlorophyll patterns from cross spectrum analysis of satellite color images, J. Geophys. Res., 93, 6789- 6798. Denman, K.L., and H.J. Freeland, 1985. Correlation scales, objective mapping and a statistical test of geostrophy over the continental shelf, J. Mar. Res. 43, 517-539. Denman, K.L., H.J. Freeland and D.L. Mackas. 1989. Comparisons of time scales for biomass transfer up the marine food web and coastal transport processes. pp. 255- 264 in R.J. Beamish and G.A. McFarlane, eds. Effects of Ocean Variability on Recruitment and an Evaluation of Parameters Used in Stock Assessment Models. Can. Spec. Publ. Fish. Aquatic Sci. 108. Forbes, J.R., K.L. Denman and rr.L. Mackas, 1986. Determinations of photosynthetic capacity in coastal marine phytoplankton: effects of assay light intensity and variability of photosynthetic parameters, Mar. Ecol. Prog. Ser. 32, 181-191. Forbes, J.R., and K.L. Denman, Distribution of Nitzschia pungens in coastal waters of British Columbia, submitted to Can. J. Fish. Aquat. Sci. Foreman, M.G.G. and R.F. Henry. 1989. The harmonic analysis of tidal model time series, Advances in water Resources 12: 109-120 Foreman, M.G.G., and R.A. Walters. 1990. A finite element tidal model for the southwest coast of Vancouver Island. To appear in Atmosphere-Ocean. Foreman, M.G.G. 1990. Barotropic tides and tidal residuals for the southwest coast of Vancouver Island. To appear in Proceedings of International Conference on Tidal Hydrodynamics, Gaithersburg MD, Nov. 15-18, 1988, ed. Bruce Parker, Wiley and Sons. -56- Foreman, M.G.G. 1990. Lagrangian studies with a tidal model for the southwest coast of Vancouver Island. To appear in proceedings of VIII International Conference on Computational Methods in water Resources, Venice, June 11-15, 1990, ed. G. Gambolati et al. computational Mechanics Publications, Elsevier. Freeland, 1988. Derived Lagrangian statistics on the Vancouver Island continental shelf. Atmosphere-Ocean, 26, 267-281. Freeland, H.J., and P. McIntosh, 1989. The vorticity balance on the southern British Columbia continental shelf, Atmosphere-Ocean, 27, 643-657. Freeland, H.J., 1990. Sea surface temperatures along the coast of British Columbia: regional evidence for a warming trend. Can. J. Fish. Aquat. Sci. 47, 346-350. Gill, A. 1982. Atmosphere - Ocean Dynamics. Academic Press, New York. Healey, M.C., R.E. Thomson, and J.F.T. Morris. 1990. The distribution of commercial trawl fishing vessels off southwest Vancouver Island in relation to fishing success and oceanic water properties and circulation, Can. J. Fish. Aquatic Sci. (in press). Hickey, B.M., R.E. Thomson, H. Yih, and P.H. LeBlond. 1990. Velocity and temperature fluctuations in a bouyancy driven current off Vancouver Island. J. Geophys. Res. (in press) . Kundu, P.K. and R.E. Thomson. 1990. Inertial oscillations observed near British Columbia. In, special Volume of Pure and Applied Geophysics, R. Hughes, Ed. (in press). Thomson, R.E., B.M. Hickey and P.H. LeBlond. 1989. The Vancouver Island Coastal Current: Fisheries barrier and conduit. pp. 265-296 in R.J. Beamish and G.A. McFarlane, eds. Effects of Ocean Variability on Recruitment and an Evaluation of Parameters Used in Stock Assessment Models. Can. Spec. Publ. Fish. Aquatic Sci. 108. Thomson, R.E. and D.M. Ware. 1988. Oceanic factors affecting the distribution and recruitment of west coast fisheries. In: DFO National Workshop on Recruitment. Can. Tech. Rep. Fish. Aquat. Sci. 1626: 31-65. -57- Ware, D.M. 1990. Climate, predators and prey: behaviour of a linked oscillating system. In: Long-term variability of pelagic fish populations and their environment. Permagon Press, Oxford (in press). Ware, D.M., and G.A. McFarlane. 1986. Relative impact of Pacific hake, sablefish and Pacific cod on west coast of Vancouver Island herring stocks. In: Proceedings of the International Groundfish Symposium, 1985. Int. North Pac. Fish Comm. Bull. 47:67-77. Ware, D.M. and G.A. McFarlane. 1989. Fisheries production domains in the Northeast Pacific Ocean. Can. Spec. Publ. Fish. Aquat. Sci. 108: 359-379. Ware, D., and R.E. Thomson. 1986. La Perouse Project: First Annual Report, 1985. DFO Report. 25p. Ware, D., and R.E. Thomson. 1987. La Perouse Project: Second Annual Report, 1986. DFO Report. 31p. Ware, D., and R.E. Thomson. 1988. La Perouse Project: Third Annual Report, 1987. DFO Report. 64p. Ware, D., and R.E. Thomson. 1989. La Perouse Project: Fourth Annual Report, 1988. DFO Report. 72p. -58- 5. SUMMARY OF MOORING, CTD AND PLANKTON NET HAUL ACTIVITY; 1989 Complete lists of cruise sampling activities and dates are presented below. Following these data, the sampling grid and mooring station locations as illustrated in Figures 2a and b are listed in full. An approximate total of 7.38 "instrument years" were logged up to December 31, 1989, beginning with the moorings in place as of January 1, 1989 (1 "instrument year" = 1 data recording instrument moored and continuously operating on site for 1 year). A total of 503 CTD and/or STD casts were completed during 1989 by all operators within the La Perouse Bank area. Fifty-one plankton net hauls were completed during 1989. -59- LA PEROUSE MONITORING PROGRAM - SAMPLING ACTIVITIES ------~ MOORING AI NOT DEPLOYED I YO 1 1-2 N/, J ------I _0 I Bl H I I I ~Dl J ------Cl ------NOT DEPLOYED I I 11,1 J EOI - NO! DEPLC:;ED ] I 1 J SI ------NOT DEPLOYED r------AES METEOROLOGICAL LA PEROUSE WINDS BUOY 8901 89100P 8950 0 0 89060 CTO SURVEY 891°0 Do 8912 8913 PBS D 0 8911 9t 8902 891°0 8950 8906 PBS 0 PLANKTON NET 8912 SURVEY 0 0 , I I I , I MONTHS 1989 J F M A M J J A S o N o -60- 5.2 LIST OF CRUISES Cruise Cruise Ident.* Ident.** Date 1989 Participant 89-01 Feb. 14- Feb. 26 O.P. / I.O.S. 89-90 89-10 Apr. 06 - Apr. 11 P.B.S. 89-10 Apr. 18 - Apr. 26 O.P. / I.O.S. 89-02 May 01 - May 12 O.P. / I.O.S. 89-50 89-03 May 24- May 27 O.P. O.E. /I.O.S. 89-11 Jun. 02 - Jun. 09 O.P. / I.O.S. 89-51 89-06 Aug. 08 - Aug. 14 O.E. / I.O.S. 89-12 Aug. 16 - Aug. 25 O.P. / I.O.S. 89-03 Oct. 03 - Oct. 22 O.P. / I.O.S. 89-13 Oct. 22 - Oct. 27 O.P. / I.O.S. NB: * Where Ocean physics, I.O.S., is involved in processing of cruise data, they have assigned a cruise identification number compatible with their system. ** Participants original cruise identification. I.O.S. = Institute of Ocean Sciences P.B.S. = Pacific Biological station o.P. = Ocean Physics O.E. = Ocean Ecology O.C. = Ocean Chemistry T.C. = Tides and Currents .'.\:.. -61- CTD/HYDRO STATIONS FOR THE LA PEROUSE MONITORING PROGRAM (INCLUDING MASS EXTENSION): MAY, 1990 VERSION ------Station Latitude Longitude Approx. Task ID N W Depth(m) ------A-LINE LA1 48 29.23 124 43.65 264 CTD/D02 LA2 48 26.25 124 51.32 312 CTD/D02 LA3 48 22.84 124 57.72 113 CTD LA4 48 19.36 125 04.12 175 CTD/D02 LAS 48 16.08 125 10.60 120 CTD LA6 48 12.63 125 17.20 120 CTD/D02 LA7 48 09.20 125 23.86 120 CTD LA8 48 05.78 125 30.40 142 CTD/D02 LA9 48 02.36 125 36.92 292 CTD LA10 47 59.02 125 43.40 900 CTD ------B-LINE LB1 48 40 40 124 59.48 33 CTD/D02 LB2 48 39.00 125 02.40 50 CTD/D02 LB3 48 37.32 125 05 58 92 CTD LB4 48 35.67 125 08.72 105 CTD/D02 LB5 48 34.00 125 12.00 109 CTD LB6 48 32.18 125 15.51 118 CTD/D02 LB7 48 24.68 125 22.10 160 CTD LB8 48 25.30 125 28.65 145 CTD/D02 LB9 48 22.00 125 34.80 152 CTD/D02 LB10 48 18.57 125 41.35 150 CTD LBll 48 15.20 125 47.75 235 CTD/D02 LB12 48 12.92 125 51.90 465 CTD/D02 LB13 48 10.60 125 56.12 810 CTD LB14 48 08.48 126 00.00 1180 CTD/D02 LB15 48 04.36 126 08.46 1450 CTD LB16 48 00.53 126 17.00 1530 CTD ------C-LINE LC1 48 50.44 125 27.73 94 CTD/D02 LC2 48 48.68 125 30.95 110 CTD/D02 LC3 48 46.95 125 34.24 120 CTD LC4 48 43.43 125 40.80 167 CTD/D02 LC5 48 39.94 125 47.40 65 CTD LC6 48 36.46 125 54.00 92 CTD LC7 48 32.96 126 00.50 131 CTD/D02 LC8 48 29.45 126 07.10 203 CTD/D02 LC9 48 25.94 126 13.70 611 CTD/D02 LC10 48 22.40 126 20.20 1239 CTD LCll 48 18.95 126 26.70 1330 CTD/D02 LC12 48 15.00 126 40.00 CTD ------62- station Latitude Longitude Approx. Task Depth (m) ------D-LINE LD1 49 00.10 125 43.80 33 CTD/D02 LD2 48 58.35 125 47.05 42 CTD/D02 LD3 48 56.61 125 50.40 46 CTD LD4 48 53.16 125 57.00 62 CTD/D02 LOS 48 49.65 126 03.60 91 CTD LD6 48 46.18 126 10.20 135 CTD/D02 LD7 48 42.67 126 16.80 520 CTD LD8 48 39.17 126 23.40 760 CTD/D02 LD9 48 35.69 126 30.00 1095 CTD LD10 48 32.20 126 36.60 1475 CTD/D02 LOll 48 28.76 126 42.94 1560 CTD ------E-LINE LEI 49 05.00 126 00.90 47 CTD/D02 LE2 49 04.30 126 04.50 55 CTD/D02 LE3 49 00.50 126 10.60 79 CTD LE4 48 56.50 126 15.10 117 CTD/D02 LE5 48 52.80 126 20.40 155 CTD LE6 48 48.50 126 26.30 197 CTD/D02 LE7 48 44.20 126 32.10 524 CTD LE8 48 40.30 126 38.00 1299 CTC/C02 LE9 48 26.40 126 20.40 1458 CTC ------F-LINE LF1 49 14.80 126 14.30 37 CTC/D02 LF2 49 13.20 126 16.50 56 CTC/D02 LF3 49 09.60 126 21.90 89 CTC LF4 49 05.90 126 27.50 126 CTD/C02 LF5 49 02.00 126 33.20 151 CTC LF6 48 58.10 126 38.90 458 CTC/C02 LF7 48 54.10 126 44.80 718 CTC LF8 48 50.00 126 50.70 1003 CTC/C02 LF9 48 45.80 126 56.80 1117 CTD ------G-LINE LG1 49 21.80 126 34.00 30 CTC/C02 LG1 49 20.50 126 35.00 55 CTD/D02 LG1A 49 19.48 126 36.56 83 CTD/D02 LG2 49 18.70 126 38.10 105 CTD/D02 LG2A 49 16.89 126. 40.83 115 CTD/D02 LG3 49 15.00 126 43.70 112 CTD LG4 49 11.30 126 49.40 146 CTD/C02 LG5 49 07.40 126 55.30 258 CTC LG6 49 03.50 127 01.20 866 CTC/D02 LG7 48 59.40 127 07.20 1800 CTC LG8 48 55.30 127 13.30 2070 CTC -63- ------station Latitude Longitude Approx. Task Depth (m) ------H-LINE LH1 49 34.30 126 44.20 35 CTD/D02 LH2 49 32.20 126 47.40 49 CTD/D02 LH3 49 28.70 126 52.90 97 CTD LH4 49 24.90 126 58.70 126 CTD/D02 LH5 49 21.30 127 04.50 156 CTD LH6 49 17.60 127 10.40 490 CTD/D02 LH7 49 13.70 127 16.40 1424 CTD LH8 49 09.70 127 22.50 1880 CTD/D02 LH9 49 05.60 127 28.70 2015 CTD ------J-LINE LJ1 49 44.30 127 02.50 63 CTD/D02 LJ2 49 42.60 127 05.30 79 CTD/D02 LJ3 49 39.10 127 11.10 128 CTD LJ4 49 35.50 127 16.90 154 CTD/D02 LJ5 49 31.66 127 22.56 1001 CTD LJ6 49 27.90 127 28.58 1040 CTD/D02 LJ7 49 24.05 127 34.72 CTD LJ8 49 20.11 127 40 96 CTD/D02 LJ9 49 16.07 127 47.33 CTD ------K-LINE LK1 49 55.50 127 18.70 37 CTD LK2 49 53.90 127 21. 70 70 CTD LK3 49 50.50 127 27.60 76 CTD LK4 49 46.90 127 33.60 134 CTD LK5 49 43.30 127 39.60 805 CTD LK6 49 39.50 127 45.80 767 CTD LK7 49 35.70 127 52.10 1064 CTD LK8 49 24.20 127 35.00 >1000 CTD -64- 6. VESSEL SCHEDULE AND OBJECTIVES 1990 Cruise Date Vessel Investigator Sampling Feb. 5-9 Tully Mackas Plank. Feb. 10-Mar. 7 Ricker MacFarlane/Saunders CTD Apr. 2-13 Ricker Jamieson CTD, Plank. Apr. 16-May 4 Parizeau Thomson/Mackas/Denman CTD, ADCP Moor. , Plank. May 7-June 1 Parizeau Tabata CTD, ADCP Moor. , Drift. June 11 - 22 Parizeau Thomson CTD, ADCP SAR, Plank. July 16 - 27 Tully Denman CTD, Drift Moor. , Plank. Jul 23-Aug 10 Ricker Hargreaves CTD, Trawls Aug. 6 - 15 Charter Ware/MacFarlane Trawling Aug. 13 - 31 Ricker Saunders CTD, Plank. Aug 20-Sept 7 Parizeau Tabata CTD, ADCP Moor. Sept. 3 - 21 Ricker Healey CTD, Fish Oct 1 - 26 Parizeau Thomson/Mackas/Denman CTD, ADCP Moor. , Plank. Oct. 29-Nov 16 Ricker Saunders CTD, Plank. Oct. 29-Nov 30 Endeavour Tabata CTD, ADCP -65- 7. LIST OF PARTICIPANTS R. Beamish, Director Biological Sciences Branch R. Brown, Ocean Ecology Division, lOS K. Denman, Ocean Ecology Division, lOS M. Foreman, Ocean Physics Division, lOS H. Freeland, Ocean Physics Division, lOS K. Groot, Salmon Dynamics Section, PBS B. Hargreaves, Salmon Dynamics, PBS D. Mackas, Ocean Ecology Division, lOS G.A. McFarlane, Groundfish Section, PBS C. Robinson, PBS, Post. Doc. Fellow, PBS W. Shaw, Groundfish Section, PBS S. Tabata, Ocean Physics Division, lOS R. Tanasichuk, Salmon Dynamics Section, PBS R. Thomson, Ocean Physics Division, lOS A. Tyler, Groundish Section, PBS D. Ware, Salmon Dynamics Section, PBS M. Woodward, Tides and Currents Section, lOS