AMJ 2001 Quarterly Rpt. AMJ 2001 sidebar
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(Quarterly
Report for April-May-June 2001)
Differences
in Distribution, Migration, and Growth of Juvenile
Sockeye Salmon in the Eastern Bering Sea, 1999 and
2000
The Auke Bay Laboratory (ABL) Ocean Carrying
Capacity (OCC) program conducted research cruises in
the eastern Bering Sea during July and September
1999 and August 2000 to study the early marine
distribution, migration, and growth of juvenile
Bristol Bay sockeye salmon, Oncorhynchus nerka.
The survey area was bounded to the west by
Cape Cheerful and to the east by the Ugashik River,
crossing the coastal, middle, and outer domains of
the eastern Bering Sea. The 1999 and 2000 surveys
were the first in a series of annual assessments to
document variations in the biological
characteristics (growth, migration, and
distribution) of juvenile sockeye salmon leaving
Bristol Bay. The objectives of the annual
surveys are 1) to determine the extent of offshore
migrations of Bristol Bay juvenile sockeye salmon
and 2) to describe the physical environment of the
eastern Bering Sea shelf occupied by juvenile
sockeye salmon. The primary goal of the
research is to establish and verify the linkages
between adult sockeye salmon survival and annual
variations in biological characteristics of juvenile
sockeye salmon.
Our survey results to date suggest that the
migration timing and distribution of juvenile
sockeye salmon in the coastal waters of the eastern
Bering Sea are influenced by environmental
conditions. The July and September 1999
surveys occurred after a cold spring in the eastern
Bering Sea, which was characterized by a delay in
the breakup of lake ice in sockeye salmon nursery
lakes and anomalously cold sea temperatures. During
July 1999, juvenile sockeye salmon were mainly
distributed in the coastal domain; we speculated
that these salmon had not migrated farther offshore
into the middle domain due to cold surface
temperatures (<6ºC) within the middle domain.
By September 1999, surface temperatures had
warmed considerably in the middle domain (>9ºC)
and juvenile sockeye salmon encountered west of
long. 160ºW were mainly distributed within the
middle domain. In contrast, our August 2000
survey followed relatively warm spring and summer
temperatures and earlier timing of lake ice breakup
than during 1999, and we observed increased sea
surface temperatures in the middle domain and
earlier offshore migrations of juvenile salmon away
from coastal waters.
Differences in migration timing and habitat occupied
by juvenile sockeye salmon in the eastern Bering Sea
may influence early marine growth. During July
and September 1999, zooplankton densities were
greatest within the middle domain and within the
coastal domain west of Port Moller. As
mentioned earlier, juvenile sockeye salmon were
mainly distributed in the coastal domain east of
Port Moller during July and within the middle domain
west of Port Moller during September. The
distribution of juvenile sockeye salmon captured in
September (within areas of higher forage densities)
may explain the significantly higher growth and
condition factor found for juvenile sockeye salmon
captured during September than those captured during
July. Furthermore, juvenile sockeye salmon caught
during the August 2000 survey were significantly
larger than those caught during the September 1999
survey (t = 2.576; p<0.01). Thus, it is
quite possible that the increased early marine
growth of juvenile sockeye salmon observed in August
2000 was due to increased sea temperatures promoting
accelerated migration westward and offshore where
zooplankton densities are greater.
Faster growing individuals may have a survival
advantage over slower growing individuals since the
survival rate of juvenile salmon apparently
increases with increased size. Our results
suggest that anomalously cold spring and sea
temperatures in the eastern Bering Sea may have
delayed juvenile sockeye salmon migration into areas
of greater forage densities, therefore, reducing
early marine growth rate. Similar observations
of early marine distribution, migration, and growth
of juvenile sockeye salmon encountered within the
coastal waters of the eastern Bering Sea during the
summer of 1971 (which followed an anomalously cold
spring) were followed by dramatically reduced adult
sockeye salmon returns to Bristol Bay 2 (1973) and 3
(1974) years later. If this qualitative
comparison holds true, then we may expect lower than
average returns of 2-ocean and 3-ocean sockeye
salmon to Bristol Bay during the 2001 and 2002
summers, respectively.
By Ed Farley.
Surf Smelt Reproduction
Confirmed in Northern Southeast Alaska
A small collection of juvenile surf smelt, Hypomesus
pretiosus, was received from the ABL Steller sea
lion forage study project in Berners Bay north of
Juneau. Eulachon, Thaleichthys pacificus, and
capelin, Mallotus villosus, are also common
in Berners Bay. This confirms that surf
smelt have a reproducing population in northern
Southeast Alaska and that at least three species of
smelt spawn in the Berners Bay vicinity.
By Bruce Wing.
Coral Reference Collection
Established
Twenty-one specimens of octocorals were returned by
the Smithsonian Institution in June 2001. The
specimens had been identified by Dr. Frederick M.
Bayer, curator emeritus, at the National Museum of
Natural History. Sixteen distinct species from 10
genera were represented. The material was part of
the 67 lots of octocorals, hydro-corals, and stony
corals submitted last spring as a cooperative
project to establish a reference collection of
Alaska corals. Much of the material gathered in the
past 2 years represents undescribed species or
species previously known only from the type
material.
By Bruce Wing.
High Seas Salmon Survey
The OCC program, along with scientists from the
Fisheries Research Institute at the University of
Washington, participated in a cooperative high-seas
salmon survey aboard the Japanese research vessel Oshoro
maru from 28 June to 10 July 2001. Immature
and maturing Pacific salmon were captured by gill
net, and over 500 salmon were sampled for diet and
stable isotope analysis for the study of trophic
dynamics of salmon in the Gulf of Alaska. All
six species of Pacific salmon were captured with
surface longlines, and 46 salmon were tagged with
archival tags (data storage tags with temperature
and pressure sensors).
By Jim Murphy.
Chinook Salmon Data Storage
Tagging Study
A new cooperative study on chinook salmon, O.
tshawytscha, by the ABL Marine Salmon
Interactions and OCC programs was launched during
the past quarter. The primary goal of the
study is to learn more about habitat utilization and
migration strategies of chinook salmon that live and
grow, at least part of their lives, in
Southeast Alaska marine waters. The study will focus
on the use of new RL-42 data storage tags which
continuously record both temperature and depth data.
Jim Murphy is principal investigator for the study,
with Bill Heard and Jack Helle as coinvestigators.
The RL-42 tags have a 3-year battery life, are
fully encapsulated in clear urethane, measure 8 x 16
x 27 mm and weigh 5 g. Depth (pressure) data range
and resolution are automatically scaled to incoming
data with a 500-m maximum. The temperature
sensor has a range of -5º to 35ºC with 0.20º
resolution. Data from recovered tags is downloaded
through a light-emitting diode to an optical reader
attached to a host computer.
A total of 48 tags were deployed on chinook salmon
in April and May 2001 at several locations in
northern Southeast Alaska using both a chartered
commercial troller and sport fishing vessel to
capture fish. Most of the fish tagged were 80-100 cm
in length with ocean ages of .3 or .4, however,
three fish were ocean age .1 and nine were ocean age
.2 fish. Additional chinook are scheduled for
tagging later this year when the focus will be on
younger ocean age .2 fish. With a 3-year battery
life, the intent is to have tags recovered from
younger, immature chinook after an extended time at
liberty in the ocean. Through analyses of extended
temperature and depth profiles of the fish’s
environment we hope to improve our understanding of
the seasonal movements of the fish. Of particular
interest is the usual midsummer appearance of
immature, feeder age-.1 and -.2 chinook salmon in
the coastal and inside waters of Southeast Alaska,
their later apparent disappearance for up to 8
months, and then their return.
A total of six tagged chinook have been recovered to
date; four were recovered in the general vicinity of
where they were tagged, one was recovered on the
Taku River in British Columbia by a commercial
fisherman, and one was recovered in the Queen
Charlotte Islands by a sport fisherman. None of the
data have yet been analyzed.
By Bill Heard.
Steelhead Studies
In the past 3 months, research at the Little Port
Walter Field Station (LPW) has focused on Endangered
Species Act (ESA)-related studies of steelhead
trout, O. mykiss. The 1996 brood that has
been held in marine net pens was inventoried in
mid-April to measure winter growth, sort out
maturing fish, and move some to fresh water for
final maturation prior to spawning. These fish all
have internal PIT (passive integrated transponder)
tags with a detailed record of growth,
smoltification, and prior maturation (if any)
history. Over-winter survival was very high
(>90%), and the fish were in excellent condition.
Sibling fish from the same brood that were
coded-wire tagged and released as smolts in 1998
began returning in April and were collected for
spawning and tag recovery at the Sashin Creek weir.
Over 150 tagged adults were recovered from the
1996 and 1997 brood years. Growth and survival
of these fish will be compared to captive siblings
that have been held through their life in marine net
pens at LPW.
Over 325 captive and released adults were spawned to
continue the genetic studies initiated from the
first spawnings in 1996. From these, 80
families representing eight distinct lines will be
cultured separately until age 1 to measure family
variability in growth and survival. At age 1 the
fish will be pooled by line and cultured to age 2
when the groups will be evaluated for early
maturation and smolting. Smolts will be
coded-wire tagged and released to measure marine
survival between groups to help determine, in part,
if maintaining stocks of a normally anadromous fish
in fresh water for many generations results in any
maladaptation when attempts are made to re-anadromize
these fish. The work is important in evaluating
proposed recovery strategies for threatened and
endangered stocks of steelhead trout and other
salmonids. The 1999 brood fish were evaluated
this June, and over 4,000 smolts from eight lines
were coded-wire tagged and released. These fish will
return from the ocean in 2003-2004.
Chinook Smolt Release
The 1999 brood year of tagged chinook salmon smolts
representing the sixth generation of hatchery
culture for the Chickamin and Unuk River stocks at
LPW were released in May. The stock origin of these
fish are from two important Southeast Alaska chinook
rivers. More than 100,000 tagged smolts were
released to maintain the two pure lineages of these
stocks at LPW, which will be used for new research
focusing on genetic and other interactions of
hatchery and wild fish. This new research effort was
made possible through increased funding for chinook
work at ABL and LPW. Smolts released this year
will result in a direct economic contribution to
commercial fishermen when the fish are captured in
2-3 years and will also contribute to the sports
fishery.
By Frank Thrower.
Hatchery and Wild Stock
Chinook Study
The first returns of mature male and female chinook
salmon from the 1996 study of the Chickamin River
hatchery and wild brood lines will be captured at
LPW during July and August 2001. Plans are underway
to collect biological and genetic information from
these fish and to spawn them as part of a breeding
design to examine behavioral and life-history
characteristics in the next generation. Scientists
from the Northwest Fisheries Science Center and the
University of Alaska will participate in the work
this summer at LPW. Returns from the 1996
brood will be studied thru 2003. Returns from a
similar study utilizing Unuk River chinook will be
studied until 2005. Results from these studies will
provide information to managers about the impacts
and interactions of hatchery-produced chinook
salmon.
By John Joyce.
Southeast Coastal Alaska
Monitoring Project
The Marine Salmon Investigations Program has
completed two of five monthly research cruises
scheduled for 2001 in continuation of its Southeast
Coastal Alaska Monitoring (SECM) Project. This
project was initiated in 1997 to study the habitat
use and early marine ecology of juvenile (age-.0)
Pacific salmon (Oncorhynchus spp). From
May through October annually, biophysical parameters
are sampled in inshore, strait, and coastal habitats
along a primary seaward migration corridor used by
juvenile salmon in the geographic area extending
from near Juneau westward through Icy Strait to 64
km offshore in the Gulf of Alaska. The project
collects data on seasonal patterns and interannual
variation in juvenile salmon distribution and
abundance, predation on them by species such as
spiny dogfish, walleye pollock, sablefish, and
immature salmon, as well as data on zooplankton food
abundance and the physical characteristics of these
habitats that could affect salmon growth and
survival.
In the SECM project’s fifth year of monitoring,
sampling locations include a station in Auke Bay and
three transects with four stations each in upper
Chatham Strait, Icy Strait, and Icy Point on the
outer coast. Stations sampled in prior years
at Cross Sound, Taku Inlet, Lower Favorite Channel,
and False Point Retreat were omitted to focus on key
sampling locations and free up time for process
studies. The standard fishing gear used is a
NORDIC 264 surface rope trawl fished for 20 minutes
from the NOAA ship John N. Cobb. Oceanographic
samples taken include a 20-m vertical haul with a
0.5-m diameter, 243-µm mesh Norpac net; a
double oblique bongo net system sample (0.6-m
diameter opening, 333-µm and 505-µm
mesh nets) to 200 m depth or within 20 m of bottom;
a 0.6-m diameter opening, 202-µm mesh WP-2
net sample to 200 m depth; surface water samples for
chlorophyll and nutrient determinations; and CTD
casts for temperature and salinity profiles. To
target the prey resource potentially most important
to juvenile salmon in the water column zone they
inhabit, a 20-m bongo sample series was added to
augment the oceanographic samples collected.
The May cruise (JC-01-05) was conducted 19-25 May,
approximately 2 weeks after the two large scale
hatcheries in northern Southeast Alaska (Douglas
Island Pink and Chum Hatchery, near Juneau, and
Hidden Falls Hatchery, located on northeastern
Baranof Island) had released approximately 130
million thermally marked chum salmon into local
marine waters. The annual May cruise is timed to
precede the departure of juvenile salmon from
near-shore waters along the beaches; therefore, in
May 2001 standard oceanographic sampling was
conducted at the 13 stations, but trawling for
juvenile salmon was limited to the 4 Icy Strait
stations. In addition, juvenile pink and chum
salmon (approximately 40-60 mm in fork length) were
sampled on beaches in Icy Strait with a 37-m long
beach seine. The primary purposes of this
nonstandard sampling were 1) to collect specimens to
document the arrival of hatchery chum salmon at
locations distant from their release sites before
they can be captured in deeper waters accessible by
trawl , 2) to collect and preserve samples of
juvenile pink and chum salmon at approximately
3-hour intervals to determine their diel feeding
rhythms, 3) to obtain live specimens of each species
for shipboard gastric evacuation experiments, and 4)
to freeze specimens of each species for later bomb
calorimetry to determine energy content (a measure
of condition). Approximately 450 individuals
were preserved, and 300 were frozen for these
purposes. Diel samples of each species were
preserved at approximately 07:00, 10:45, 14:00,
18:00 and 21:00 on 21-22 May. Evacuation
sample series were started at 06:50 and sacrificed
roughly 1, 2, 4, 6, 8, 11, 14, 24 and 32 hours
later.
The June cruise (JC-01-09) was conducted 26 June to
2 July. Standard oceanographic sampling and surface
trawling were conducted at the 13 stations. In
addition, a diel sample series was collected
by trawling at 3-hour intervals at an Icy Strait
station over 2 days. Feeding periodicity will
be determined from pink, chum, and coho salmon
stomach samples collected on 29 May at 04:00, 07:00,
10:00 and 13:00, and on 30 May at 13:00, 16:00,
19:00 and 22:00. The evacuation experiments
could not be conducted on this cruise because
catches were too low to obtain sufficient specimens,
and fish were in poor condition after trawling.
For chum salmon, no catches exceeded 40-60
individuals, catches of pink salmon were even lower,
and fish were badly descaled. The feeding
periodicity samples will be repeated during the next
SECM cruise (27 July - 2 August). The
evacuation experiments also will be attempted during
the July cruise. The fish should survive the
trawl in better condition because of their larger
size and because of a higher abundance of jellyfish,
which cushion the fish in the cod end of the trawl.
By Molly Sturdevant, Alex Wertheimer, and Joe Orsi.
Auke Lake Sockeye Salmon
Smolt Migration
The NMFS Auke Creek Weir provides the opportunity to
enumerate and sample both upstream and downstream
migrating salmonids. The ABL has
compiled historical data series consisting of
sockeye salmon adult and smolt counts and biological
information. Preliminary data from 2001
indicate above average numbers of smolts are leaving
the system and that some are unusually large. In
Auke Lake sockeye salmon spawn in the larger
tributaries and on submerged gravel beds in the
lake. The production of wild sockeye smolts
from Auke Lake was first estimated in 1961. From
1961 through 1979, smolt numbers were estimated
several times, but some of the early smolt estimates
are known to be incomplete. The pre-1980 smolt
estimates lack continuity, and based on the pre-1980
escapements, it is obvious there has been a
significant decrease in the number of smolts since
the 1960s and early 1970s. The 1961 estimate
of 90,000 smolts is the highest on record, and
estimates from 1962 through 1979 ranged from 8,862
to 62,389. Since 1979, the entire smolt population
has been counted at Auke Creek weir, and the number
of wild smolts ranged from 1,719 to 33,616.
Hatchery-reared sockeye fry stocked in Auke Lake in
1974-75 and 1987-89 contributed to the smolt
production in subsequent years. Sockeye
enhancement in the late 1980s and early 1990s
included the release of underyearling smolts that
were reared in the hatchery and net pens in Auke
Bay. Adults returning from enhancement
projects contributed to the escapements and
subsequent smolt production. The average
number of wild smolts produced in Auke Lake,
1980-2001, is 16,897 (Figure 1 below). In 2001, a
total of 21,428 sockeye smolts were counted at Auke
Creek weir during the downstream migration. The
downstream migration of sockeye smolts began in
early May, and about 15,000 smolts migrated during
the last week of the month. The migration
midpoint was 27 May, 3 days later than average.
All sockeye salmon smolts in 2001 were from
natural spawning in the Auke Lake system. Scale
analysis revealed that 41% (8,754) of the smolts
were age-1, 1999 brood fish and 59% (12,674) age-2,
1998 brood fish. The 1998 brood completed the
freshwater phase of its life history and produced a
total of 16,429 smolts, slightly less than the
average 17,259.
Figure 1. Sockeye salmon smolt migration,
1980-2001; the horizontal line represents the wild
fish average.
One measure of freshwater
survival, the number of smolts produced per spawner,
indicates that for the last 13 brood years fewer
than 10 smolts were produced per spawner in Auke
Lake. The 1998 brood production of eight
smolts per spawner, was the highest in 7 years
(Figure 2 below). In 2000, age-1 and -2 smolts
averaged 77 and 131 mm, and 3.9 and 19.6 g,
respectively (Figure 3 below). The age-2
smolts were some of the largest on record leaving
Auke Lake. The long-term average for age-1 and
-2 sockeye smolts leaving Auke Lake is 75 and 107
mm, and 3.9 and 12 g, respectively.
Figure 2. Sockeye salmon smolts produced per
spawner by brood year.
Figure 3. Average weight of sockeye salmon
smolts, 1961-2001.
Total biomass zooplankton models
indicate Auke Lake is capable of producing about 350
kg of smolts annually. The total biomass of
sockeye smolts (estimated total weight of all smolts
in a migration year) from Auke Lake in 2001 was 282
kg (Figure 4 below ). This was greater than
the average of 142 kg and was the second highest on
record for Auke Lake.
Figure 4. Total annual biomass of sockeye
salmon smolts leaving Auke Lake.
(data are not available in all years)
By Jerry Taylor.
First Frederick Sound Cruise
of the Southeast Alaska Steller Sea Lion Prey Study
Completed
The first cruise in Frederick Sound for the
Southeast Alaska Steller sea lion prey study was
completed during 22 May to 2 June 2001. The purpose
of the study is to test the hypothesis that juvenile
sea lion prey diversity and seasonality are related
to Steller sea lion population trends. The
study is a comparison study to one being conducted
around Kodiak Island by the University of Alaska.
During the Frederick Sound cruise, prey
abundance was measured using echo-integration and a
midwater trawl. Scat was collected to infer
diet. Fish also were collected for proximate
and free fatty acid analysis. Prior to the
cruise, Alaska Department of Fish and Game (ADF&G)
scientists satellite-tagged sea lions in the area;
the location information from the tagged
animals was very helpful for conducting our cruise.
Mostly juvenile walleye pollock and some
Pacific herring were found at depths less than 75 m,
adult pollock were found from 75 to 250 m, and
Pacific whiting were found deeper than 250 m. Both
day and night sampling was conducted to determine if
availability of fish sea lion foraging depths was
affected by time of day. There was little
day-night difference in fish depth difference except
that some adult pollock were found at shallower
depths during night. Sea lions were found at
three haulouts in Frederick Sound near The Brothers
(Sunset Island, Sail Island, Southwest Brothers
Island); the number hauled out totaled about 1,300
animals.
Scientists aboard the vessel were Mike Sigler,
Johanna Vollenweider, and Dave Csepp of ABL and
Olivier Cheneval of the University of British
Columbia. Quarterly sampling is planned for
the Frederick Sound study area with the next cruise
scheduled for September 2001.
By Mike Sigler.
Juvenile Sablefish Tagging
Cruise
The annual juvenile sablefish tagging cruise in
Southeast Alaska was conducted aboard the John N.
Cobb in Saint John the Baptist Bay from 12 to 15
June and in Silver Bay from 15 to 16 June. A total
of 110 fish were captured with hook and line jigging
gear in Saint John the Baptist Bay in 128.5 rod hrs
(0.86 fish/rod/hr); 105 fish were tagged and
released. One previously tagged fish
(# 16132) was measured (length 46 cm) and released.
No fish were captured in the vicinity of
Silver Bay. An underwater video camera was
used by the crew to document juvenile sablefish
taking bait from the jigging gear without taking the
hook. This type of video information may
enable the design of more efficient jigging gear in
the future.
By Dean Courtney.
Effects of Trawling
Members of the ABL Groundfish Program conducted an
effects of trawling study off Kodiak Island, 11- 18
June. Program staff were Bob Stone (project
leader), John Karinen, Pat Malecha, Jon Heifetz, and
Phil Rigby. The study used Delta
Oceanographic’s submersible research vessel Delta;
the contracted sub tender AJ, and the
contracted Kodiak fishing vessel Peggy Jo.
The study area, 10 miles offshore of Cape
Chiniak, was approximately 1,300 m by 600 m and
consisted of three corridors: a control corridor and
a corridor each for a single trawl pass and for
multiple (six) trawl passes. The site is an area
closed to trawling in approximately 140 m of water
and with large numbers of sea whips distributed
throughout.
Before and after trawling by the Peggy Jo,
the control and treatment corridors were sampled
using the Delta for strip transects and with
a Shipek grab sampler for infauna, sediment, and
carbon composition. The Peggy Jo used a
Bering Sea 107/136 combination (flatfish) trawl. The
vessel location was plotted with navigation
equipment on board the trawler, and door spread and
net height were measured with an acoustic
mensuration system. Location of the net with
an attached transponder was tracked from the AJ
with a track point system operated by the Delta
crew. Observed evidence of trawling consisted
of shallow grooves on the seafloor from discs on the
net’s footrope, bent and damaged sea whips,
dislodged anemones, and narrow tracks from the trawl
doors. Although damage to sea whips was evident in
the multiple pass corridor, the numbers remaining
and the lack of deep furrows was less impact than
expected by the investigators. Such observations are
very preliminary, and results from the analysis of
the benthic samples and transect counts should be
available in spring 2002.
By Phil Rigby.
Surveys of Heavily Fished
Areas of the Gulf of Alaska
The Sustainable Fisheries Act of 1996 was passed to
attain long-term protection of essential fish
habitat and specifically requires that NMFS minimize
adverse impacts to essential fish habitat by
fisheries. There is little knowledge of what
the bottom habitat looks like where major fisheries
occur. Without knowledge of whether or where
vulnerable habitat is at risk, measures adopted to
minimize impacts may be ineffective or unnecessarily
restrictive.
The ABL Groundfish Program is conducting a study to
find, describe, and map habitat vulnerable to
fishing impacts. Vulnerable habitat is believed to
occur on rough, hard, or steep bottom. Vulnerable
habitat in soft bottom areas such as sea whip beds
or coral habitat in inshore areas where little
trawling takes place is not the objective of this
phase of our study. Rough bottom is believed to
occur often on the shelf area near steep slopes.
Rockfish are typically found on rough bottom,
based on the type of gear used by trawlers targeting
rockfish. Using the research submersible Delta
during 19-23 June, the Groundfish Program
characterized habitat on Portlock Bank, Alaska, in
the vicinity of rockfish fishing grounds. Program
staff were Robert Stone and Pat Malecha. Twelve
dives at six sites were completed. Surprisingly,
the bottom was primarily soft sediments and pebbles
with few large rocks or rock outcroppings. Small
hard corals and some damaged sponges were observed.
In August, we plan to map the area using multibeam
acoustic technology.
By Jon Heifetz.
Surveys of Habitat Areas of
Particular Concern
Habitat Areas of Particular Concern (HAPCs) are
types of Essential Fish Habitat (EFH) that are
deemed especially vulnerable to anthropogenic
impacts. Gorgonian corals, especially red tree
coral (Primnoa sp.), are HAPCs that are
thought to be particularly vulnerable to the impacts
of fishing gear. The North Pacific
Fishery Management Council (NPFMC) has proposed that
specific sites in Alaska be closed to fishing that
have significant amounts of gorgonian coral. Using
the research submersible Delta during 25-30
June, members of the Groundfish Program surveyed the
biological and physical aspects at two of these
sites; one located off the southwestern tip of the
Kenai Peninsula and the other near Yakutat. Program
staff were Linc Freese and Pat Malecha.
By Jon Heifetz.
Estuarine Wetland Survey
Estuarine wetlands are among the most productive
habitats for fish that sustain marine fisheries
worldwide, yet little is known about their role in
the productivity of Alaska fisheries. There
have been no comprehensive surveys of the extent or
quality of fish habitat in Alaska estuaries,
however, there is evidence that some estuaries may
be under stress from human activities. For
example, nearly 60 coastal streams listed by
the State of Alaska as impaired water bodies drain
into estuaries. Consequently, estuaries in
urban areas are currently considered habitat areas
of particular concern by the Alaska EFH Core Team
In 1998, ABL scientists proposed research on EFH in
Alaska’s estuaries to help NMFS managers
develop an understanding of the functional role of
estuaries in Alaska fisheries and coastal health.
The objectives of the work are 1) to identify and
describe EFH for species covered by fishery
management plans (FMPs) in estuarine wetlands
throughout Southeast Alaska; and 2) to develop means
of estimating and predicting effects on estuarine
EFH as coastal development takes place.
Previous research has documented the use of
estuaries near Juneau by 19 species of fish in the
NPFMC FMP. Groundfish (e.g., yellowfin sole,
rock sole, starry flounder), anadromous salmon, and
important forage species (sand lance, herring,
eulachon, and many invertebrates) are plentiful in
those estuaries. In addition, a habitat
classification system is being developed to stratify
and map estuarine fish habitat. Habitat types that
have been identified and sampled include emergent
marsh wetlands, mud flats, sloughs, and sand and
gravel beaches. A demonstration geographic
information system (GIS) was developed for the
Mendenhall Wetlands near Juneau to test the use of
existing digital imagery and maps in identifying
estuarine EFH. Digital photography, NOAA
charts, and National Wetland Inventory maps have
been integrated with data on fish abundance and
habitat classification gathered by NMFS scientists.
A GIS that can be used to evaluate the extent
and value of fish habitat in the Mendenhall Wetlands
was developed from those data. The methods
developed in this work can be used to generate a
regional GIS for estuarine EFH and eventually to
help provide more accurate GIS coverages for
other EFH.
In July 2001, NMFS scientists began the process of
ground truthing additional Alaska estuaries
for comparison to EFH found in the Mendenhall
Wetlands. Two sites in the Icy Strait and
Cross Sound area (Mud Bay and Port Althorp) were
sampled. Preliminary findings indicate a shift
in fish diversity and water chemistry in estuaries
nearer the outer coast. That information will
be important in developing a regional GIS capable of
estimating estuarine habitat quality and
productivity.
By Mitch Lorenz.
2001 Sablefish Longline
Survey
The AFSC has conducted an annual longline survey of
sablefish and other groundfish in the Gulf of Alaska
since 1987. The survey is a joint effort
involving the ABL and the Resource Assessment
Conservation Engineering (RACE) Division. Beginning
in 1996, biennial sampling of the Aleutian Islands
region and eastern Bering Sea was added.
The 2001 survey began 2 June and will end 3
September. The survey vessel is the chartered
fishing vessel Ocean Prowler. As of this
writing, the survey has sampled the eastern Bering
Sea, the western Gulf of Alaska, and three
seamounts. Orca whales (Orcinus orca) took
fish from the longline at five stations in the
Bering Sea which is similar to previous years.
Catch rates appear to be up from last year’s
survey for both areas. In the western Gulf
19,300 sablefish were caught and average length was
66 cm. The same stations produced 13,445 fish in
2000. Early indications are that there was a
strong 1997 year class that is now showing up in
survey catches.
A study initiated in 1999 to determine the extent,
if any, of seamount-to-slope and
seamount-to-seamount sablefish migration continued
during 2001. Three seamounts were sampled
during the vessel’s transit from Sand Point to
Ketchikan at the end of Leg 2. Sablefish catches
were down slightly from last year on Surveyor and
Welker Seamounts. Dickens Seamount, which was
sampled for the first time this year, is shallower
and rockier than other seamounts we have sampled,
and rougheye and shortraker rockfish made up about
one third of the catch. Male sablefish
outnumbered females by a wide margin on all three
seamounts. About 1,000 sablefish were tagged and
released on the three seamounts, bringing the total
number of tags released on seamounts since 1999 to
just less than 2,700. Twenty-one tags were
recovered from sablefish tagged in previous years,
and one sablefish which was tagged in the Aleutian
Islands region in 1982 was recovered on Dickens
Seamount.
By Chris Lunsford and Nancy Maloney.
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