2.0. OPERATIONS
Scheduling of individual activities will depend upon weather conditions
and progress of scientific work, therefore, firm advance scheduling of
events will not be possible, and a continual dialogue between scientific
and ship's personnel will be especially important. To insure fulfillment
of all the scientific objectives, the ship will steam at maximum cruising
speed whenever time in transit and between stations is greater than three
hours. A standard oceanographic watch will be utilized which consists of
a winch operator and a scientific staff of four. Operations will be conducted
24 hours a day. A fishing crew will be required to assist with the Methot,
midwater and bottom trawls to be conducted in daytime or nighttime. They
will be conducted at times and locations to be determined by the Chief
Scientist, based on acoustic signal and juvenile abundance. Collections
of juvenile pollock for growth and condition studies will be made as well
as adult fish for examining predation during the juvenile survey.
2.1. SUMMARY OF ACTIVITIES
a) Depart Dutch Harbor on the morning of 6 September and proceed to
offshore end Line D off St. George Island (Fig. 1) and begin CTD survey
heading north. Stations should be approximately 9 km apart, but closer
spacing may be needed inshore (Table 1). Water
bottles for collecting nutrients and chlorophyll samples should be used
at stations specified by the project scientists. An acoustic transect (38
and 120 kHz) should be done both day and night on this transect. Tucker
tows and Methot, anchovy or bottom trawls will be made along this transect
at stations specified by the Chief Scientist. Up to 2 days will be spent
at this transect.
b) Proceed to the inner front of Line C on the north side of St. George
(Fig. 1). Conduct similar physical, biological and acoustic sampling operations
as described in previous section over a complete diel cycle (2 days) sampling
both at the front and on both sides of the front.
c) Proceed to front on Line B south of St. Paul and continue physical,
acoustical and biological sampling as before (2 days).
d) Proceed to front on Line A north of St. Paul and continue physical,
acoustical and biological sampling as before (2 days).
e) Depending on progress of the survey, the ship will return to an area
of high juvenile pollock density determined previously and do a diel series
sampling at the same station.
f) After disembarking 2-3 scientists, the ship will depart the Pribilof
Island area and begin occupying the CTD/bongo stations shown in Fig. 1
on about 14 September (Fig. 1; Table 1). Depending
on weather, this transect should take about 4 days to complete and the
ship will return to Dutch Harbor on 18 September for offloading. If time
is available, we may request 2-3 midwater tows over deep water to collect
micronektonic fish and squid.
2.2 PROCEDURES FOR OPERATIONS:
See the attached sheets from FOCI Field Manual for more specifics on
each gear described below.
CTD/Water Sample Operations
The CTD should descend at a rate of 30 m/min for the first 200 m and
45 m/min below that. The ascent rate should be 50 m/min. The FOCI fluorometer,
light meter, and chlorophyll absorbance meter (ChlAM) should be mounted
on the rosette for all casts where possible. We request the use of a rosette
with up to 11 Niskin bottles and the use of the ships CTD and deck unit.
Methot trawl
The Methot trawl is deployed off the stern of the vessel. A Scanmar
acoustical depth sensor, with a readout in the trawl house The ship's speed
should be 5-6 km/hr. This trawl will be deployed at 40 m/min and retrieved
at 20 m/min. Tows will be oblique or stepped oblique from 100 m to the
surface. Methot trawls may be conducted in daytime or at night, as where
and when they will be done depends on plankton catches or acoustic sign.
Location and time of tows is at the discretion of the Chief Scientist or
scientific watch leader.
Tucker tows
The Tucker trawl will have three nets with 0.333 mm mesh netting and
will be used in a standard manner. A 20 cm Clarke Bumpus frame with 0.150
mm mesh nets will be mounted in nets 1 and 2. Depth of the net will be
monitored with the ScanMar depth sensor. The net is deployed at constant
wire speed of 40 m/min to 5 m off bottom. The winch is stopped and the
net allowed to stabilize for 30 sec. A messenger is sent, opening the first
net. The nets are retrieved at a wire speed of 20 m/min. The ship speed
is adjusted to maintain a 45 degree wire angle during the entire tow. If
both nets are to be used, at a predetermined depth, a second messenger
is sent, closing the first net and opening the second, which is allowed
to stabilize and then is retrieved as before. When the nets reach the surface,
they are brought aboard and hosed down to wash the sample to the codend
and flowmeters are read.
Anchovy trawls
Anchovy midwater trawls will be requested for catching age-0 and age-1
pollock. Midwater trawls will be deployed using standard procedures for
the gear requested. The Chief Scientist or Watch Chief will decide trawl
locations, times and depths. As with the Methot trawls, the midwater trawls
will be conducted day or night and will depend on plankton catches or midwater
sign seen on the EK-500 echosounder. Generally, the anchovy trawl will
be set in a layer of fish and kept at that depth for 10-30 minutes depending
on the amount of sign. Once a trawl is called for, regardless of the time
of day, the fishing crew will need to be activated quickly, with little
time lost.
Bottom trawls
Bottom trawls will be requested for collecting predators on juvenile
pollock. Bottom trawls will be deployed using standard procedures for the
Russian trawl. The Chief Scientist will decide trawl locations, times,
and depths. As with the Methot trawls, the bottom trawls will be conducted
day or night and will depend on plankton catches or bottom sign seen on
the EK-500 echosounder.
Bongo tows
Two bongo net frames will be used on this cruise during the monitoring
transect to Dutch Harbor. The bongo will include two 20 cm and two 60 cm
bongo frames together on the same line. The 60-cm frame will have 333 m
mesh netting and will be used in a standard manner. The 20-cm frame will
have 150 m mesh netting. Depth of the net will be monitored with the ScanMar
depth sensor. The net is deployed at constant wire speed of 40 m/min to
a desired depth. The winch is stopped and the net allowed to stabilize
for 30 sec. The nets are retrieved at a wire speed of 20 m/min. The ship
speed is adjusted to maintain a 45 degree wire angle during the entire
tow. When the nets reach the surface, they are brought aboard and hosed
down to wash the sample to the codend and flowmeters are read. Tows not
meeting specifications may be repeated at the discretion of the scientific
watch.
Chlorophyll Samples
Chlorophyll samples will be taken from the 2-liter Niskin bottles. Sampling
depths depend on the fluorescence profile. A typical strategy would be
samples at 0, 10, 20, 30, 40, and 50 or 60 m depending upon which is closest
to the fluorescence maximum obtained from the CTD. When microzooplankton
samples are to be collected from the same Niskin bottle, 500 ml of water
is first removed from the water bottle using a graduated cylinder. Chlorophyll
and nutrient samples are obtained from the 500 ml in the graduated cylinder.
EK-500 Monitoring
The Simrad EK-500 Scientific 38 and 120 kHz Echosounder will be turned
on during all scientific operations and should be monitored regularly for
the presence of unusual acoustic signals or heavy fish sign. A trained
scientist should be available on each watch to begin logging data and to
record ship speed and course changes on the traces and file names in the
notebook provided. The printer pen cartridges and paper should be replaced
as needed. The EK-500 settings will be set at the beginning of the cruise
and remain the same throughout the cruise.
3.0. FACILITIES AND EQUIPMENT
The following systems and their associated support services are essential
to the cruise. Sufficient consumables, back-up units, and on-site spares
and technical support must be in place to assure that operational interruptions
are minimal. All measurement instruments are expected to have current calibrations,
and all pertinent calibration information shall be included in the data
package.
3.1 Equipment and Capabilities to be Provided by the Ship
* Oceanographic winch with slip rings and 3-conductor cable terminated
for CTD,
* 2-liter sampling bottles for use with rosette (11 plus 4 spares),
* CTD and software for collection and processing,
* Readout for oceanographic winch to be used with bongo net,
* Meter block for plankton tows,
* Wire speed indicator and readout,
* Freezer space for storage of fish, nutrient, and chlorophyll samples
(blast and storage freezers),
* Bottom trawl with fine mesh liner and doors,
* Simrad EK-500 echo sounder with 38 and 120 kHz transducers,
* Laboratory space with exhaust hood, sink, lab tables and storage space,
* Sea-water hoses and nozzles to wash down nets,
* Adequate deck lighting for night-time operations,
* Navigational equipment including GPS and radar.
3.2 Equipment to be Provided by FOCI
* Fluorometer, light meter, and chlorophyll absorbance meter (ChlAM)
mounted on CTD,
* Temperature thermistors for CTDs (one for primary system, one for
back up system),
* 20 and 60 cm. bongo frame and net and spares, codends, flowmeters,
* Wire-angle indicator,
* Scanmar depth sensing unit,
* Color printers for EK-500,
* 100 m2 Anchovy trawl,
* 5' x 7' steel doors,
* 5 m2 Methot frame and trawl,
* Tucker trawl and nets, codends and flowmeters
* Vacuum pump for filtering chlorophylls
* Miscellaneous scientific sampling and processing equipment (scales,
measuring boards),
* Sorting baskets for processing trawl catches.
4.0 SCIENTISTS
We will need bunk space and meals provided for up to 11 scientists during
this two week cruise. The scientists will get on the evening of 5 September
in Dutch Harbor and get off the evening of 18 September following the unloading
of the scientific gear. If possible, several scientists will get off in
St. Paul on 14 September A full day should be available for loading and
unloading the vessel in Dutch Harbor.
