3.4 Cruise Plan - The research will be conducted in phases (experiments).
Phase 1 will be to occupy CTD/Bongo stations on one line across the Alaska Coastal Current and around a box near Unimak Pass (Figure 1, Table 1; ca. 1 day). CTD casts will include water bottles to sample chlorophyll, phytoplankton, nutrients, and absorption spectra. Standard MARMAP bongo tows (60 and 20 cm nets) will be done at most stations. Satellite-tracked buoys may be deployed.
Phase 2 will be a large-scale bongo survey of larval pollock and zooplankton in the southeastern Bering Sea shelf (Figure 2, Table 2a; ca. 2 days). During the grid, CTD casts with water bottles for chlorophyll, phytoplankton, nutrients, and absorption spectra may be done as well as special Larval Condition tows. The station grid will be continually updated by the Chief Scientist as the cruise proceeds. Stations may be added or deleted at any time at his discretion. Approximately 24 bongo stations are anticipated. Calibration samples will be taken at mooring 95BSM-1, using CTD/water bottles and MOCNESS (with TAPS). ARGOS-tracked drifters may be released during this phase.
Phase 3 will be a feeding/predation study in the southeast grid at a location of high larval abundance (ca. 1 day). Before beginning the operations we will launch the Freeman RADAR buoy; all samples will be taken around the buoy as it drifts with the current. MOCNESS samples for larval vertical distribution and gut contents, bongo samples for larval condition, CTD/water bottle samples for prey concentration, and larval predator samples (1 m2 Tucker trawl) will be taken. Satellite-tracked drogues may be deployed during this operation.. At the end of the operations the RADAR buoy must be recovered.
Phase 4 will be calibration measurements at moorings 2 and 3 during our transit to the northwest grid (Table 3; ca. 1 day). A CTD cast with water bottles (for chlorophyll and nutrients) and a MOCNESS tow (with TAPS) will be taken at each mooring.
Phase 5 will be the deployment of moorings 95BSM-4 and 95BSM-5 (Table 3). Before proceeding to the deployment sites, we will pick up personnel at Saint Paul Island. This involves small boat operations. After deployment, CTD calibration casts will be conducted near the moorings.
Phase 6 will be a large-scale bongo survey of larval pollock and zooplankton in the northwestern portion of the eastern Bering Sea shelf (Figure 2, Table 2b; ca. 5 days). During the grid, the CTD with water bottles for chlorophyll, phytoplankton, nutrients, and absorption spectra will be used as well as special Larval Condition tows. The station grid will be continually updated by the Chief Scientist as the cruise proceeds. Stations may be added or deleted at any time at his discretion. Approximately 45 bongo stations are anticipated. Calibration samples may be repeated at moorings 95BSM-4 and -5 using the CTD and water bottles. ARGOS-tracked drifters may be released during this phase.
Phase 7 will be a repeat of Phase 3 except that it will be in the northwestern portion of the eastern Bering Sea shelf (ca. 1 day).
Phase 8 will be the return transit to Dutch Harbor. Before leaving the northwest grid, several 0.75 m ring net/CalVET tow(s) for adult copepods/nauplii must be taken over the outer shelf for sorting and shipment to University Alaska, Seward Marine Station. A second set of tows will be taken in the southeastern portion of the operations area before arriving in Dutch Harbor. Calibration samples for the moored instruments will be taken en route, if time permits.
Special Ship's Loading Considerations
The two northwest moorings (buoys, towers, and instruments) must be
placed on the ship prior to MF95-07. In addition, one or two satellite
drifters will need to be loaded.
Eddy Contingency Plan
If an eddy is found to be in the operations area, then the Chief Scientist
may exercise his option to implement this experiment and rearrange the
rest of the cruise schedule accordingly. A 5 x 5 grid of stations spaced
15 - 20 km apart and oriented north/south will be placed on the chart by
the Chief Scientist, FOO, and OOD. The first pass will be a continuous
track for surface temperature, salinity, fluorescence, and ADCP and EK500
profiles (Figure 3). The second stage will be occupation of all stations
for Bongo/SeaCat tows. Satellite-tracked drifters will be deployed during
this operation. The third stage will be an occupation of all stations (in
a different order) for SeaBird CTD/Rosette casts. Water for nutrients,
microzooplankton, and chlorophyll samples will be collected at selected
stations. The penultimate pass will be for depth specific capture of larval
fish and zooplankton predators and prey using the MOCNESS and Tucker trawls.
The last stage will be a repeat of the first pass using our continuous
underway sampling system, the ADCP, and EK500.