FOCI Number: 3WE98
OSU Ship: WECOMA
Area of Operations:
Southeast Bering Sea and Gulf of Alaska
Depart Dutch Harbor June 17
Arrive Kodiak June 30
NOAA - Alaska Fisheries Science Center (AFSC)
NOAA - Pacific Marine Environmental Laboratory (PMEL)
| Chief Scientist:
| Matthew T. Wilson
| Participating Scientists:
| Bill Rugen
| Lisa Britt
| Jay Clark
| Steve Porter
| Sherrie Rees
1) Recover a mooring that broke free from its anchor in the SE Bering Sea,
2) Survey the distribution of age-0 pollock in the western Gulf of Alaska
for purposes of estimating abundance and mortality,
3) Collect samples of juvenile pollock for studies of growth, osteology,
gear comparison (Methot versus Bongo nets) and the effects of preservation
method on body shrinkage,
4) Collect samples of juvenile pollock prey using a modified Clarke-Bumpus
5) Occupy Line 8 in Shelikof Strait to maintain a time series of biological
and physical sampling for El-Nino and NPZ special requests,
6) Ground-truth instrumented moorings located near Line 8 for El-Nino
and NPZ special requests,
7) Sample in the exit region of Shelikof Strait to determine the effects
of the 1997/1998 El Nino on the transport of fish into Shelikof Strait,
8) Collect information on nutrients, phytoplankton, and zooplankton (NPZ)
to be used in mathematical models.
9) Collect age-0 pollock from an eddy to be used for growth and genetic
a) On 17 June, 11:00 ADT, we left Dutch Harbor and headed north into
the Bering Sea toward the mooring M2 which had broke free. At station 1
(Table 1, Figure 1), the mooring buoy and all instruments, including the
acoustic release, were recovered - all appeared to be in fine shape except
the lowest CTD which had been dragged over the bottom and was badly damaged.
Below the acoustic release was about 2 m of chain terminated with an intact
shackle all else was lost. Except for the acoustic release, everything
that was recovered was off-loaded in Kodiak and was stowed by Paul Anderson
and Rich McIntosh of the NMFS Kodiak Lab. The acoustic release was kept
aboard the Wecoma by Hugh Milburn for possible use during the next cruise.
b) Station 2 was sampled on 19 June, 1300 ADT, with the Methot net and
this was the first of 96 Methot tows at 91 stations (Table 1 and 2). Four
pre-planned stations were dropped because they were inaccessible. Excess
time allowed twelve stations to be added giving a more even coverage of
the area within the survey boundary (Figure 1). Although unplanned, pollock
rough counts were taken and used to estimate the number of pollock per
10 m2 (Figure 2). When fewer than 70 of these fish were collected, those
saved for otoliths (< 21) were measured to the nearest 0.5 mm using
a ruler. The overall mean length of these fish (n=1049) was 24.2 mm SL,
they ranged from 11 to 45 mm SL. Many of the pollock collected along the
east coast of Kodiak Island (Stations 123 and 125) were noticeably large
giving a relatively large mean size per haul but these fish were collected
last (Table 3).
At seventeen stations (Table 1), the 60 cm bongo net (505 micron nets)
was fished after the Methot net to verify that the Methot was not missing
many small fish. Very few fish were collected in the bongo net and, although
they were not measured, they appeared to be similar in size to those collected
by the Methot. At ten other stations (Table 1), the large Clarke-Bumpus
net was suspended in the mouth of the Methot net to collect potential prey
of age-0 pollock. At three stations (Table 1), a second Methot tow was
conducted to collect fish for osteological and shrinkage studies (Table
2). Sampling with the Methot at Station 75 (Table 1, Figure 1) was requested
by Jeff Napp during the cruise to collect pollock in an eddy as indicated
by a drifter. This sampling was restricted to approximately one hour (three
good tows and one failure) due to low fish densities (11 fish/tow), shallow
water (38 m) relative to the drogue depth (40 m), and time constraints.
The fish (n=33) collected near this drifter were preserved in 95% ethanol
for otolith and genetic studies. All of these net tows were oblique from
near-bottom to the surface; however, the distance off-bottom was quite
variable due to intermittent operation of the Scanmar electronics.
Surface temperature was measured several different ways. Coarse measurements
were made with a bucket thermometer, incremented in whole degrees celsius,
until it broke about midway through the cruise. Temperatures were recorded
off the ship's flow-through system but they tended to be warmer than the
bucket reading. A micro-bathythermograph (MBT) was attached to the Methot
net. In addition to surface temperature, the MBT provided temperature profiles
over the tow path at many stations. After one use, the MK7f temperature
and light recorder was abandoned because the value of the data was judged
insufficient to warrant the additional deck time needed to operate it.
Records of the ship's flow-through system were saved on disk as were the
ADCP data although this was not requested.
c) Beginning on 27 June at 20:24 ADT, we began the requested sampling for
El-Nino and NPZ studies of Napp, Kendall, and Hinckley. This sampling was
fully completed and involved CTD casts, bongo (20 and 60 cm), Tucker (1
m2), and CalVET net tows (Table 1, Figure 3). At some of the exit-region
stations the bottom depth was >500 m so the Tucker net was fished only
to 250 m. All of these deepwater stations were classified as second-priority
sampling. The last of the exit region stations (Station 122) was surprisingly
shallow (40 m), nevertheless, the requested operations were completed.
During net tows, the Sea-Cat was used to indicate gear depth and the resultant
temperature and salinity data were saved to disk.
Table 1. Cruise Summary pg.1,
Table 2. Cruise Statistics
Table 3. Standard length of pollock preserved for otoliths.
Figure 1. Plot of the mooring recovery station and all Methot stations.
Figure 2. Plot of the pollock catch (fish per 10 m2) from Methot grid samples.
Figure 3. Map of El-Nino and NPZ stations.