amj99 Quarterly Rpt. sidebar
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(Quarterly Report for April-May-June 1998)
Salmon
Survey in the North Pacific Ocean and Southeastern Bering Sea
A 30-day survey of the ocean
distribution of immature and mature Pacific salmon and associated marine species was made
in coastal waters off Alaska and Washington and the high seas of the Gulf of Alaska and
central North Pacific Ocean during April and May 1998 by Auke Bay Laboratory (ABL) staff.
The work is part of a cooperative international research effort coordinated through
the North Pacific Anadromous Fish Commission to examine distribution, growth, and survival
of Pacific salmon during their ocean life.
The survey was conducted on the
chartered fishing vessel Great Pacific, a 38-m-long stern ramp trawler. The
survey focused on nearshore and oceanic distribution of salmon off the eastern Aleutian
Islands, Alaska Peninsula, and Washington coast and on the high seas of the central
Gulf of Alaska (GOA) from lat. 50ºN to 55°N and along long. 145°W from the northern GOA
(lat. 50°-59°N) to the central North Pacific Ocean (lat. 38°-55°N). Sampling gear was
a midwater rope trawl towed at 5 knots at surface with typical spread to 18 m depth and 52
m width. The survey included three oceanographic transects at Scotch Cape, Cape
Chiniak, and Cape St. Elias. Plankton tows and conductivity-temperature-depth (CTD)
casts were conducted with surface trawl effort on the high seas.
Total catch of salmonids was 1,493
fish, including 881 immature and 612 maturing adult salmon. Immature salmon were 602
sockeye, 184 chum, and 95 chinook. Maturing adult salmon were 322 chum, 141 sockeye,
107 pink, 6 chinook, and 36 coho. Most immature salmon were sockeye taken in the Bering
Sea, and most maturing adult salmon were chum taken in the northern Gulf of Alaska and in
high seas tows. Catches of maturing salmon on the high seas varied between chum and
sockeye with one species predominate, the other few or none. Noteworthy were catches
of immature sockeye salmon, 20-30 cm fork length (FL), off Cape Cheerful in the
southeastern Bering Sea and immature chinook salmon, 31-35 cm FL, off Foggy Cape in
southwestern Shelikof Strait. Other fishes taken included juvenile sablefish, adult
and young walleye pollock, Pacific herring, Pacific mackerel, jack mackerel, juvenile
shad, and 18 oarfish over Juan de Fuca Canyon. Sea surface temperatures ranged from
3.6°C in the Bering Sea to 12.5°C in the central Pacific Ocean. Storms and heavy
seas limited early sampling off the Aleutian Islands and efforts offshore in the central
Gulf of Alaska.
By Richard Carlson and Ed Farley.
Kuroshima
Oil Spill Response
The freighter Kuroshima grounded
in Summer Bay near Dutch Harbor, Alaska, in November 1998 during a violent, 90-knot wind.
Although some cleaning and oil removal on beaches was accomplished in the first few
weeks, winter weather and winds hampered the response effort, and except for salvaging the
vessel, all response activities ceased during the winter. The vessel was refloated
in early March, and cleanup efforts were renewed in early April 1998. The strong
winds causing the grounding also caused leaking oil to contaminate the nearby
shoreline and Summer Lake, a salmon lake separated from the marine environment by a sand
barrier beach. About 75% of the lake shoreline was contaminated. After the
winter ice cover melted divers confirmed bottom sediments were also contaminated. In
April, ABL divers sampled the lake sediments in a grid pattern over the entire lake.
Chemical analyses of these samples confirmed sediment contamination throughout the
entire lake with a concentration of oil globs in the north end. Most sediments were
in the low hundreds of parts per billion (ppb) of polynuclear aromatic hydrocarbons (PAH),
with some samples ranging as high as 24,000 ppb of PAH. The damage to salmonid
populations is unknown. Pink salmon fry and smolts of sockeye and coho salmon have left
the lake system through a weir operated by the Alaska Department of Fish and Game
(ADF&G), indicating that total year-class failure is not a problem.
By Jeep Rice.
Intragravel
Exposure of Pink Salmon Embryos to Crude Oil
Research following the Exxon
Valdez oil spill in 1989 continues to suggest the negative impacts of oil
exposure on pink salmon eggs intertidally exposed to crude oil. Researchers at the
ABL have attempted to simulate intragravel exposure by incubating pink salmon embryos
under three exposure conditions: 1) in direct contact with oil-coated gravel, 2) in
effluent from oil-coated gravel, and 3) in direct contact with gravel coated with very
weathered oil (VWO). Embryo mortalities and PAH accumulation in embryo tissues
during the direct-contact and effluent exposure experiments were not significantly
different, indicating that PAH accumulation was mediated by aqueous transport.
Mortality rates for embryos exposed initially to a total PAH concentration (TPAH) of
1.0 ppb were significantly higher than mortality rates for controls when the PAH were
derived from VWO. The same aqueous TPAH concentration failed to increase mortality rates
when the PAH were derived from less weathered oil, indicating that toxicity of effluents
from the VWO was primarily associated with the greater PAH concentration. We conclude that
water quality standards for TPAH above 1.0 ppb may fail to protect fish embryos. Further,
pink salmon embryos incubating in Prince William Sound (PWS) after the Exxon Valdez
oil spill may have accumulated lethal concentrations of PAH from interstitial water that
was contaminated when it percolated through oil reservoirs located upstream from salmon
redds. There are two significant issues with this research effort. First, it
corroborates the oil toxicity mechanism of elevated egg mortalities observed by the
ADF&G through 1993, 4 years after the spill. Second, along with the larval
herring study (see below), these are the lowest effective oil concentrations showing
negative effects from an oil spill ever reported.
By Ron Heintz.
Low-level
Exposure of Pacific Herring Eggs to Weathered Crude Oil
Malformations were observed in
Pacific herring (Clupea pallasi) larvae in PWS following the Exxon Valdez
oil spill. In an effort to understand the role oil exposure might have played in
these observed changes, ABL researchers exposed two groups of Pacific herring eggs for 16
days to weathered Alaska North Slope crude oil in the laboratory in spring 1995. The
composition of the oil to which eggs were exposed was closely similar to oil compositions
observed in PWS after the spill. Oil-contaminated water used in our experiment contained
the same PAH compounds observed in PWS, including naphthalenes through chrysenes.
The ratios of these compounds change as weathering occurs, both in the environment
and in the laboratory, and can be described by first-order loss-rate kinetics. Our
experiments included a less-weathered oil with relatively more naphthalenes and fewer
larger compounds such as phenanthrenes, and more weathered oil with relatively fewer
naphthalenes and more large compounds. Weathering effects observed in PWS
encompassed those of the laboratory study, thus our methods simulated conditions observed
in PWS following the spill. Exposure to an initial aqueous concentration of 0.7 ppb
PAH caused malformations, genetic damage, mortality, and decreased size, and inhibited
swimming ability. Total aqueous PAH concentrations as low as 0.4 ppb caused
sublethal responses such as yolk-sac edema and immaturity consistent with premature
hatching. Responses to less weathered oil, which had relatively lower proportions of
high molecular weight PAH, generally paralleled responses to more weathered oil, but
lowest observed effective concentrations (LOECs) were higher (9.1 ppb), demonstrating the
importance of composition. The LOEC for more weathered oil (0.4 ppb) was
similar to that observed for pink salmon (1.0 ppb), a species with a very different
development rate. By inference, other species may be similarly sensitive to weathered oil.
Biological effects including temporal and physical evidence of premature hatching, small
size, edema, and genetic damage were identical to those observed in larval herring
from PWS in 1989 and support the conclusion that the Exxon Valdez oil spill caused
significant damage to herring in PWS. Previous demonstration by our laboratory in
1990 that most malformed or precocious larvae die corroborates the decreased
larval production measured after the spill.
By Mark Carls.
Genetic Stock
Identification of Chum Salmon Caught in Bering Sea Trawl Fishery
Laboratory analysis of Southeast
Alaska hatchery chum salmon has been nearly completed for addition to the North Pacific
chum salmon genetic baseline. Recoveries of thermally-marked chum salmon in the
Bering Sea trawl fishery indicate that significant numbers of Southeast Alaska hatchery
chum salmon are caught in this fishery. The expanded genetic baseline should allow
us to quantify the presence of these hatchery fish in the bycatch. The genetic
samples from the 1996 Bering Sea trawl fishery chum salmon bycatch (the last year samples
were collected from this fishery) are nearly finished, and genetic stock
identification analysis will begin in the fourth quarter.
By Richard Wilmot.
Yukon River
Fall-Run Chum Salmon Radio Tagging Study
The major components for
installation of satellite radio-tag tracking towers were obtained and shipped to the Yukon
River for installation on the upper section of the river in Canada, and on the Chandalar
and Sheenjek Rivers on the U.S. side of the border. As part of this cooperative
international project between Canada and the United States, tagging and tracking of fall
chum salmon will begin next quarter when the fish arrive in the river.
By John Eiler.
Chinook Salmon
and Hatchery-Wild Stock Interaction Studies
Increasing concern about the effects
of cultured salmonids on wild salmon populations prompted the initiation of studies
designed to measure the effects (if any) of hatchery practices on the behavior, growth,
and survival of chinook salmon in Southeast Alaska. These studies, begun in 1996, are
examining interactions of progeny from fourth generation hatchery chinook salmon and the
undisturbed, parental wild population from which they were derived.
Gametes from wild Chickamin River
stock chinook salmon and the NMFS Little Port Walter (LPW) Chickamin River stock were
collected in 1996. The LPW stock originated from a small founder population of
gametes collected from the Chickamin River in 1976, with no subsequent introduction of
wild gametes. The LPW stock has been maintained by the culture and release of
coded-wire tagged age-1 smolts as part of a long-term ocean ranching, stock enhancement
research program. In 1996, the wild and hatchery gametes were used to create four
groups of progeny: wild × wild, hatchery × hatchery, wild × hatchery and hatchery ×
wild. Each group was incubated and cultured separately. The ability of fry
from these groups to avoid predation was tested by a series of exposure trials to fish
predators during May 1997. In May 1998, the predation ability of the smolts from
these groups was evaluated by exposing pink salmon fry to the smolts in a variety of
experimental conditions. A third experiment evaluated the freshwater culture
performance of the groups in a replicated design. Finally, smolts from each group
were coded-wire tagged and released from LPW in May 1998 to evaluate marine survival,
fishery contribution, and age at maturation.
Knowledge gained from these studies
will provide important data concerning the risks associated with hatchery selection and
will aid in evaluating the impacts of straying and introgression of hatchery fish into
wild populations. Pending adequate funding, further studies are planned using other
hatchery stocks and the undisturbed wild populations from which they were derived.
Different paired populations of wild and hatchery chinook salmon stocks in Southeast
Alaska provide a unique opportunity to examine the potential impacts of hatchery selection
without the confounding effects of a different stock history or severe habitat
degradation.
By John Joyce.
Steelhead/Rainbow
Trout Studies at Little Port Walter Field Station
In spring 1996 scientists at LPW
initiated a study to begin examining the effects of long-term freshwater sequestration on
progeny of anadromous steelhead trout. Over 60 years ago, wild steelhead trout (Oncorynchus
mykiss) fry were collected from Sashin Creek, Alaska, and stocked into Sashin Lake,
which until then had been without fish and separated by a barrier falls from the endemic
anadromous run of steelhead trout in the lower creek. Round Lake, part of the Sashin Creek
drainage, is also separated from Sashin Lake and the lower creek by a second barrier falls
and was stocked 12 years later with fish from Sashin Lake. Both lakes now have
healthy resident populations of steelhead trout that still produce migratory smolts, are
reproductively isolated from each other, and are partially isolated from the anadromous
steelhead population in the lower portion of the creek. In the intervening 60 years
no other stocking into any of these populations has occurred.
Results of the LPW study are
expected to provide scientific information on 1) the effects of long-term sequestration in
fresh water on genetic variability; 2) the effects of small founder population size on
genetic variability; 3) the effects of long-term sequestration on anadromous smolt
production capability and marine survival; and 4) the effects of long-term sequestration
on important life history parameters such as embryo survival, size of fry, and long-term
growth, survival, and maturation rates. These results could have important implications in
determining the potential role of resident rainbow trout to the genetic heritage of listed
ESUs (evolutionary significant units) of steelhead and in determining the most
effective restoration strategies for stocks in peril. Presently there are no
salmonids in Alaska listed under the Endangered Species Act (ESA), and this research is
designed to provide basic scientific data to aid in ESA salmonid recovery programs in the
Pacific Northwest.
To date, the study has succeeded in
producing 80 families of resident rainbow and steelhead trout and crosses between the
types of the 1996 brood year. These crosses have been raised to smolt stage and resulted
in the first release of anadromous smolts from the study in June 1998. In addition,
6,600 passive-integrated-transponder-tagged fish from the same families are being reared
in captivity to maturity to determine which crosses provide the best genetic mix to use in
captive brood programs for ESA recovery plans.
An additional 80 families were
produced from the 1997 brood year and are currently under culture at LPW.
Microsatellite DNA and mitochondrial DNA have been examined from the donor
steelhead population and the current resident lake population, and allozyme analysis will
be conducted this summer to compare variation between the populations. The first
returning adults from the study are expected in the year 2000, at which time the second
phase of the study, examination of outbreeding depression, will begin.
By Frank Thrower.
Juvenile
Sablefish Studies
Off Southeast Alaska, sablefish
spawn in deep waters (200-300 m) in late winter (January-February). During
development, the buoyant eggs rise toward the surface, the larvae hatch and rise towards
the surface and finally occupy the neuston layer, where they feed and grow rapidly to
120-130 mm by late summer. Studies conducted in recent years in conjunction with the NMFS
annual sablefish longline survey found young-of-the-year (YOY) sablefish in surface waters
along the continental slope of the Gulf of Alaska. In late summer, YOY sablefish
move shoreward from their oceanic distributions and have been found along the coast and in
nearshore bays. They have been taken in surface rope-trawls during juvenile salmon
studies in the fall and found in the stomachs of silver salmon taken in the coastal troll
fishery. At least some juvenile sablefish apparently overwinter in inshore locations
such as St. John the Baptist Bay where they have been found throughout their first winter
and the following summer. Tagging juveniles during this stage of their life cycle
has provided valuable assessment information, such as the age of recruitment to the
offshore fisheries, and has provided a valuable tool for validating ageing methods of
sablefish.
Biologists from ABL and the
AFSCs RACE Division tagged juvenile sablefish in inshore waters of Baranof
Island in Southeast Alaska during a cruise of the NOAA ship John N. Cobb during
5-11 May. Approximately 1,200 juvenile sablefish (age 1+) were tagged and released
at St. John the Baptist Bay and Silver Bay, near Sitka. This was the fourteenth
consecutive year of sampling at St. John the Baptist Bay. While juvenile sablefish
have been found only sporadically in other nearshore areas, they are typically found in
abundance at St. John the Baptist Bay. Strangely, only 50 juvenile sablefish (age
1+) were caught and tagged there in 1997.
By Jeff Fujioka and John Karinen.
Sablefish
Longline Survey Under Way
The first two legs of the
AFSCs annual Sablefish Longline Survey have been completed; they covered the
Aleutian Islands region and the western Gulf of Alaska. The survey is conducted by
the ABL and RACE Divisions and covers the Gulf of Alaska annually and the Bering Sea and
Aleutian Islands region in alternate years. The survey charter vessel Alaskan Leader
completed Legs 1 and 2 (1-29 June) and transited the Gulf of Alaska from the western
gulf to Dixon Entrance in the eastern Gulf of Alaska to begin the third leg of sampling at
stations from Dixon Entrance to Yakutat. This sequence of coverage has been altered from
past surveys to avoid interaction with major trawl fishery openings in the central and
western gulf in July. The survey catch rates are critical in determining the annual
allowable biological catch of sablefish, and the reduction of influences from fishery
activities decreases the uncertainty in the assessment.
Effects of
Trawling on Benthic HabitatStudies With a Submersible
A description of the seafloor
habitat in heavily trawled and protected regions of the central Gulf of Alaska near
Kodiak Island was obtained during a cruise during 4-17 June aboard the State of Alaska
research vessel Media using the submersible Delta as an observation
platform. The objective of the cruise was to assess changes to the seafloor and
organisms caused by chronic, long-term trawling in three areas of the central Gulf of
Alaska. Specific objectives are to compare nontrawled areas to trawled areas to
determine if changes have occurred to 1) infauna and associated demersal zooplankton, 2)
epifauna, 3) fish populations associated with the seafloor, and 4) seafloor
characteristics including grain-size composition, sorting of sediments, and total organic
carbon content. Weather and sea conditions prevented diving on several days so only
two areas were studied: near Chiniak Bay and the Trinity Islands. All videos taken
on the transects over trawled and nontrawled areas were reviewed at sea to quantify
benthic epifaunal assemblages, demersal fish, and physical characteristics of the
seafloor. Sediment samples of the upper 10 cm of the bottom were obtained for all
transects using a 0.04-m2 Shipek grab. Samples were sieved through 1-mm
and 0.5-mm screens, and the biota obtained from the samples were preserved in 5%
seawater-buffered formaldehyde containing 0.5 g/L Rose Bengal. Processing of samples and
video data is currently under way. We thank Captain Wade Loofbourrow and the crew of
the Media and the pilots and crew of the Delta for their assistance,
dedication, and effort to make the cruise a success.
By John Karinen.
Internal Tags
Will Tell Secrets of Sablefish Movements
Fifty-four electronic
temperature-depth tags were surgically implanted in sablefish during the first two legs of
the 1998 Sablefish Longline Survey. In all, approximately 200 of these tags will be
released during the course of the survey. The data-logging life of the tags is
dependent on user-specified sampling protocol. Maximum logging life is 11 years, and the
data will be retained for up to 20 years. Data obtained from recovery of these tags are
expected to provide useful information on diurnal movements and timing of inshore-offshore
migration, and might help to refine estimates of movement rates between regulatory areas
obtained from conventional tagging studies. There is a $100 reward for return of recovered
tags.
By Nancy Maloney
Has El Niño
1997-98 Lost Its Punch?
As of 30 June 1998, sea surface
temperature anomalies in the Gulf of Alaska and the Bering Sea are negative except for a
warm core in the central gulf and slightly warmer water along Southeast Alaska.
Positive anomalies still are present in surface waters occupying a large area north
and south of the equator off South America but there as yet appears to be little northward
movement of this warm core. The multivariate ENSO index (NOAA-CIRES Climate
Diagnostics Center) sharply declined from March-April to June-July (2.5 to 1.0) as
predicted by several models. The rate of decline is presently similar to El Niño
events of 1972-73 and 1982-83, both of which reverted to a La Niña episode.
El Niño 1997-98 may be on the wane,
but its effects are still evident in Southeast Alaska. Air, Auke Lake temperatures,
and sea surface temperatures monitored at the ABL are above average from May 1997 through
June 1998. Precipitation has been below average since December 1997. The
combination of increased winter temperatures and lower precipitation resulted in a reduced
snow pack and lower spring runoff to Auke Lake. We suspect that this contributed to
the lower number of out-migrant sockeye salmon and coho salmon smolts observed at the Auke
Creek weir.
By John Karinen and Bruce Wing.
Reference
Collection
Dr. Bruce Wing, curator of
ABLs reference collections, collected specimens of three species of hoplonemerteans
(ribbon worms) for Drs. Donald Jensen and G. Orti. The two University of Nebraska
researchers are using biochemical and mitochondrial DNA genetic techniques to examine
evolutionary trends and the nemertean theory of vertebrate origin. Wing also
confirmed the identification of several species of fish and invertebrates for Habitat
Investigations Essential Fish Habitat Task. Included were range extensions of
the blackeye goby, Coryphopterus nicholsi, and kelp perch, Brachyistius frenatus,
not previously known from Alaska. Finally, Wing received a roughtail skate,
Bathyraja
trachura, for the collections from Mr. William Razpotnik, Taku Fisheries. Juneau,
Alaska. This rare skate was caught by a sablefish longline at about 600 fathoms west
of Cross Sound, Alaska.
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