ond 1998 Quarterly Rpt. sidebar
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(Quarterly Report for Oct-Nov-Dec 1998)
Salmon
Migrations in Yukon River
A large-scale radio tagging
program was conducted on Yukon River fall chum salmon in 1998. The program had
four primary components:
installation of remote tracking
stations in the Yukon River drainage to record movements of radio-tagged fish
implementation of a large-scale
tagging study on fall chum salmon to collect information on run characteristics and fish
handling response
implementation of a feasibility
study on chinook salmon to assess handling response
development of an automated
database and geographical mapping system (GIS) to summarize telemetry data.
Support for the program was provided
by the Auke Bay Laboratory (ABL), U.S. Fish and Wildlife Service (USFWS), Alaska
Department of Fish and Game (ADF&G), Canadian Department of Fisheries and Oceans, and
Tanana Chiefs Conference. Field operations were completed in late October, and the
information presented in this summary should be considered preliminary.
Prior to the 1998 field season,
remote telemetry tracking stations were installed near the tagging site (60 km
upriver from the Yukon-Tanana River confluence), U.S.-Canada border on the Yukon River
main stem and the Porcupine River, and the Fishing Branch River. In 1998, additional
stations were installed on U.S. tributariesthe Chandalar, Sheenjek, Black, and lower
Porcupine Riversand the Yukon River main stem near Circle, Alaska. Stations were
also installed on Canadian sections of the Yukon River main stem and the Kluane River to
record radio-tagged fish entering and leaving two chum salmon index areas. A total
of 16 tracking stations operated during 1998.
Adult salmon were captured with fish
wheels located at Rampart Rapids on both banks of the river. Fifty chinook salmon
were tagged with radio transmitters from 22 July to 11 August, and 530 fall chum salmon
were tagged from 24 August to 16 September. Transmitters were inserted through the mouth
and placed in the stomach of the fish. The fish responded well to tagging, with 45
(90%) chinook salmon and 497 (94%) fall chum salmon resuming upriver movement after
release. Sixteen chinook and 26 fall chum salmon were caught in U.S. and Canadian
fisheries upriver from the tagging site.
Radio-tagged fall chum salmon were
tracked to areas throughout the upper Yukon River basin. Of the 471 fish that moved
upriver and were not caught in fisheries, 294 (62%) traveled to areas in the Yukon River
main stem, whereas 177 (38%) were located in the Porcupine River drainage. Fish
returning to the Chandalar River made up the largest portion of the main stem sample, with
164 (35%) fish tracked to this area. Eleven fish were last located in the U.S.
section of the Yukon River main stem upriver from Circle. Thirty (6%) fish also
remained in U.S. areas associated with the Yukon Flats; this component may include fish
caught in the fishery but not reported, mortalities due to predation or handling, and fish
utilizing main-stem and off-channel areas. Eighty-nine (19%) fish traveled to the
Canadian section of the Yukon River main-stem; of these, 64 fish remained between the
U.S.-Canada border and the Yukon-Pelly River confluence, 10 fish in the main stem index
area, 5 fish upriver from the Yukon-Tatchun Creek confluence, and 10 fish in the Kluane
River.
Sheenjek River fish were the primary
component of the Porcupine River returns, with 123 (26%) fish returning to this area.
Nine fish were tracked to the Black River, 9 fish to the U.S. section of the
drainage, and 36 (8%) fish to the Canadian section, including 14 fish that traveled to the
Fishing Branch River. Aerial surveys in late October located nine fish in the
Canadian portion of the Porcupine main stem and two fish in the lower Miner River.
These fish were located near areas of open water, and at one site untagged fish were
also observed. Fall helicopter surveys of the Chandalar and Sheenjek Rivers also
provided information on specific spawning locations.
Time of stock passage past the
tagging site varied for different groups of fish. Chandalar River fish were abundant
at the tagging site throughout the study, comprising 30% to 40% of the weekly sample of
captured fish. A similar pattern was observed for Sheenjek River fish, which
comprised between 21% and 35% of the weekly sample. Fish traveling to the Yukon
River main stem were encountered later in the season, comprising 7%-8% of the sample
during the first 2 weeks of the study and 20%-23% of the sample during the last 2 weeks.
Fish traveling to the Kluane River, however, were only encountered during the first
and second week of sampling. Porcupine River fish were present throughout the
tagging period.
Numbers and associated proportions
reported here are preliminary and only represent the distribution of fish in the
radio-tagged sample. Stock composition and timing estimates for the entire fall chum
return will be developed by weighting telemetry data with abundance estimates developed
from a mark-recapture study conducted by the USFWS.
Movement rates were determined for
fish moving to different sections of the drainage. Average movements ranged from 36
km/day to 44 km/day, with fish destined for areas farther upriver tending to exhibit
faster rates. The fastest movement rate observed was 54 km/day for a fish traveling to the
upper reaches of the Porcupine River. Further analyses will include examinations of
stock-specific movements within different sections of the drainage.
Information on handling and tagging
methods is currently being evaluated. During the first 2 weeks of tagging, 240
fall chum salmon were separated into three treatment groups: 1) fish that were radio- and
spaghetti-tagged immediately after capture and released, 2) fish that were radio-tagged
immediately after capture and released, and 3) fish that were held in a live box for 3-5
hours, radio- and spaghetti-tagged, and released. Fish tagged and released
immediately after capture resumed upriver movements sooner than fish that had been held.
Information on distribution and movement patterns will be summarized by
treatment groups.
Radio-tagged chinook salmon were
located only in sections of the Yukon River main stem; no fish were observed in the
Porcupine River. Twenty-eight fish moved upriver and were not caught in fisheries.
Of these, 18 (64%) fish were tracked to upper reaches of the drainage, including 1
fish that remained in the United States upriver from Circle, 4 fish past the U.S.-Canada
border, and 13 fish upriver of the Yukon-Pelly River confluence. Ten fish remained
in U.S. areas associated with the Yukon Flats; this component may include fish caught in
the fishery but not reported, mortalities due to predation or handling, and fish utilizing
main stem and off-channel areas. Information on movement patterns is being summarized.
Chinook salmon moved substantially faster than fall chum salmon, with average
movement rates ranging from 52 km/day to 61 km/day. Response to handling (held in
the fish wheel live box versus immediate release) is also being analyzed.
The automated database-GIS map,
developed to assist in summarizing telemetry data, was used effectively during the 1998
season. Although a prototype, the system operated throughout the study and was
essential in monitoring the remote tracking system, preparing inseason summaries used to
assess chum salmon returns, and planning field operations. Additional work is being
conducted to refine and enhance the systems capabilities.
By John Eiler.
Genetic Stock
Identification Studies
Laboratory analysis of allozyme data
from Southeast Alaska wild and hatchery chum salmon populations is nearly completed.
Addition of these data to the North Pacific chum salmon genetic baseline will improve our
understanding of chum salmon population structure in the North Pacific Ocean. It
will also improve estimates of stock identification for studies addressing chum salmon
migration in the North Pacific. One migration study currently under way is based on
chum salmon incidentally caught during the 1996 Bering Sea trawl fishery-the last year
samples were collected from this fishery.
Allozyme analysis of samples from
Sashin Creeks wild steelhead population and current resident populations in Sashin
Lake (stocked once 60 years ago from Sashin Creek) and Round Lake (stocked once 48 years
ago from the new Sashin Lake population) is complete. ABL staff at Little Port Walter
Field Station (LPW) will use the data to compare genetic variation between donor
populations and current resident rainbow trout populations over time.
Allozyme analysis of immature
sockeye salmon collected in the Aleutian Islands region in 1998 is under way. The
immature sockeye salmon were collected off Cape Cheerful, northern Unalaska Island
(n=432), and Cape Prominence, southern Unalaska Island (n=301), as part of the 1998 spring
and fall trawl surveys for the Ocean Carrying Capacity Program.
Laboratory analysis of even-year
pink salmon from southern Southeast Alaska and northern British Columbia is nearly
completed. Data analysis will begin in March 1999.
The Genetic Stock Identification
Program is organizing the 1999 Pink and Chum Salmon Workshop to be held 3-5 March in
Juneau, Alaska. Anyone interested in attending or contributing papers should contact
Sharon Hawkins, workshop chair, at Auke Bay Laboratory, 11305 Glacier Hwy., Juneau, AK
99801-8626. Tel: (907) 789-6081 Fax: (907) 789-6094
Email: sharon.hawkins@noaa.gov
By John Pohl.
Probing Behavior
of Pink Salmon Examined
As a result of the ABLs 1997
Pink Salmon Straying Study, ABL staff were able to quantify probing rates of pink salmon.
Strays are fish that return as adults to spawn in nonnatal streams. Probing
occurs when salmon first enter a stream and then, for an unknown reason, leave the stream
and spawn in another. Thus homing and straying fish may probe streams before selecting a
final spawning location. While probing behavior has been documented in the past, no
estimate has been made of its frequency.
The straying study required that we
mark and release adult pink salmon in eight of the most productive streams in lower
Chatham Strait. This afforded us an opportunity to examine probing because we could
identify fish marked in one stream and recovered in another. We modified the
Petersen population estimator used to calculate escapements to these streams by accounting
for estimates of probing. We also calculated variances for our estimates of both
escapement and probing.
Escapement estimates for the eight
streams ranged from 8,858 to 77,343. We estimated that between 42 and 1,800 fish
probed the streams in lower Chatham Strait, and these fish accounted for 0.6% to 11.5% of
the salmon found in those streams. The number of fish probing a given stream was unrelated
to the magnitude of the escapement or the number of stray fish recovered in that stream.
Thus, escapement estimates for pink salmon that fail to account for probing fish may be
biased.
By Jacek Maselko.
Comparison of
Schnute Growth Parameters for the Mussel, Mytilus trossulus
Using two types of growth data
(age-length and growth-increment), we compared growth of mussels collected near Montague
Strait in Prince William Sound by using the Schnute general growth model. Models of
Mytilus
growth have commonly been based on length-at-age data with the von Bertalanffy or Gompertz
formulations. The Schnute general size-age growth model incorporates these formulations as
well as many others as submodels. A modification of the Schnute model allows the use of
mark-recapture data if one of the parameters, usually the starting age, is specified
beforehand. Mussels at northwest Montague Island and Bay of Isles, Knight Island,
were tagged in July 1997 and collected in July 1998. Mussels were tagged with
individually-numbered plastic tags, and a plastic reference marker was glued to the
posterior edge of the shell. Age was determined from surface growth rings on the shell,
and maximum shell length was measured. Growth increment was measured from the
reference marker to the posterior edge of the shell. Bootstrap intervals were
obtained for all parameters of the model and for model predicted lengths at each annulus.
In a cross-check of the model forms, the age-length form yielded the exact same parameters
as the growth-increment form, thereby confirming that the two model forms were analogous.
The confidence intervals of the age-length form of the model did not overlap those of the
growth increment form which predicted somewhat higher growth rates. Inherent differences
in age-based versus length-based models may account for some of the difference. The
age-length model was based on individual growth accumulated over several years, whereas
the growth-increment model was based on growth over one year. Interannual variability in
growth rate probably played an important role in the differences observed.
By Charles OClair.
New Options
Considered for Salmon Enhancement in Southeast Alaska
A series of meetings organized by
the ADF&G are under way to review the history of chinook salmon enhancement and
management in Southeast Alaska and to consider possible options for future enhancement in
the region. The meetings are an outgrowth of long-standing coastwide issues
surrounding chinook salmon, including the current impasse in reaching agreements on
U.S.-Canada Salmon Treaty accords, continued harvest of depressed non-Alaska stocks in
regional fisheries, and pending new Endangered Species Act listings of Pacific Northwest
chinook salmon stocks caught in Alaska fisheries.
The first meeting was held in Juneau
March 1998 in conjunction with the Chinook Planning Team for Southeast Alaska, followed by
stakeholder meetings in October and November. The stakeholder meetings were hosted
by the Northern Southeast Regional Aquaculture Association in Sitka and the Southern
Southeast Regional Aquaculture Association in Ketchikan. The primary purpose of
these meetings was to review mitigation obligations to the Alaska commercial troll fleet
because of the 1985 Pacific Salmon Treaty (PST). Following the meetings, subcommittees
were organized to focus on management and production issues facing the region with the
possible view toward new enhancement activities, in part, to meet prior mitigation
obligations.
Rebuilding depressed chinook salmon
populations coastwide was a major objective of PST. To accomplish this objective,
parties to the treaty agreed to harvest limits in certain chinook salmon fisheries to
reduce harvest rates and increase escapements. This agreement included a reduction
of 100,000 chinook salmon relative to the average historical catch in Southeast Alaska.
Provisions in the treaty permitted mitigation of this loss through a hatchery
add-onhatchery production of chinook salmon not in place at the time of the
treaty that could be harvested in addition to the treaty-imposed limits.
The Federal Government provided $20
million to fund enhancement projects to mitigate the effects of the treaty on Southeast
Alaska fisheries. The projects were to produce 100,000 chinook salmon for harvest by
the commercial troll fleet, as well as producing sockeye and chum salmon to offset
reductions in transboundary river harvest of these species by net fisheries. Roughly
half of the mitigation funds were spent on chinook enhancement projects, but the result of
these efforts have fallen short of the goal of producing 100,000 harvestable chinook for
commercial trollers.
There are several reasons for
this shortfall. Although numerous management actions have been taken to increase the
troll harvest of Alaska hatchery chinook salmon, including special openings to target on
these fish as they return to production facilities, the average annual exploitation rate
of chinook salmon by trollers is only 23% of fish produced. The distribution
and behavior of these fish, combined with management constraints on harvest of non-Alaska
chinook salmon, restrict the ability of the troll fleet to effectively target Alaska
hatchery chinook salmon.
Another reason for the
shortfall involves the relatively low marine survival rate of hatchery-produced chinook
salmon smolts compared to hatchery-produced coho salmon smolts. Average
smolt-to-adult survival for coho salmon has been 3-6 times the 1.5%-3.0% average survival
of yearling chinook salmon smolts over the past 10 years. One likely reason for this
difference is the longer marine life history of chinook salmon compared to coho salmon.
The higher marine survival rate for coho salmon combined with an exploitation rate of coho
salmon by the troll fleet twice that of chinook salmon has prompted redirecting some
hatchery production from chinook salmon to coho salmon to better benefit the troll fleet.
The Management and Production
Subcommittees are scheduled to meet again in late January 1999 to develop a draft report
for the ADF&G. The report will likely consider a number of options for new
enhancement efforts in the region consistent with current Pacific salmon issues. Any
new enhancement effort directed at the troll fishery in Southeast Alaska
probably would include a mixture of chinook and coho salmon projects and would be
dependent on additional Federal funding. A new research program to provide the best
science for any renewed enhancement production of chinook or coho salmon in Southeast
Alaska may also be considered in the report.
Because of past research and
expertise on salmon enhancement issues, the ABLs Marine Salmon Interactions staff
have been active participants in this series of meetings and in the current
review process. Staff personnel involved include Frank Thrower, a member of the
Southeast Chinook Planning Team, Alex Wertheimer, a member of the Pacific Salmon
Commissions Chinook Technical Committee, and John Joyce, Principal Investigator on
hatchery-wild stock interaction studies at LPW.
By William Heard.
Stock
Assessments for Sablefish and Rockfish
Stock assessment activities in the
fourth quarter involved data analysis, report preparation, review and discussion of status
of stocks, and participation in Plan Team meetings where recommendations for harvest
quotas are developed for presentation to the North Pacific Fishery Management Council
(NPFMC). Preliminary stock assessment reports on Alaska sablefish, slope rockfish, and
pelagic shelf rockfish were prepared by staff at ABL and discussed at the initial meetings
of NPFMC groundfish plan teams on 14 -17 September 1998. Final reports and
acceptable biological catch (ABC) recommendations were presented at the Plan Team meetings
in Seattle 16-19 November 1998 and, following acceptance by the plan team, to the NPFMC.
(See REFM Division report in this issue.) Authors of the reports for sablefish were Mike
Sigler and Jeff Fujioka of the ABL and Sandra Lowe of the REFM Division; for slope
rockfish - Jon Heifetz and Dave Clausen of the ABL and Jim Ianelli of REFM; and for
pelagic shelf rockfish - Dave Clausen and Jon Heifetz of the ABL. An additional
report analyzing size and distribution of Pacific ocean perch in localized areas of the
central Gulf of Alaska was submitted by Chris Lunsford of the ABL. Rockfish
assessments were made for the Gulf of Alaska (GOA); the sablefish assessment included the
Aleutian Islands area, the eastern Bering Sea, and the Gulf of Alaska.
The ABC for the combined Aleutian
Islands, eastern Bering Sea, and GOA sablefish stocks decreased 5% to 15,900 metric tons
(t). Sablefish stocks in Alaska have been declining since the late 1980s and have
been mainly dependent upon only two strong year classes. A strong showing of
juvenile sablefish, age 0+ in 1995, will hopefully result in good recruitment to the
fishery in 3-4 years.
Preparations for upcoming sablefish
longline surveys are under way. A draft Request for Proposals for the 1999 and 2000
sablefish longline surveys was prepared and sent to the potential bidders in early
November 1998 for comment.
Data from the observer and the
sablefish logbook programs are also utilized to estimate the status of sablefish stocks.
Seventeen vessels in 1997 and 21 vessels in 1998 participated in the voluntary
logbook program. Most of these vessels fished in the central and eastern Gulf of Alaska.
These log data are especially useful because they supplement observer-collected data,
which are sparse in the eastern GOA. Cooperation of fishermen involved in these programs
is greatly appreciated.
Very little new assessment data were
available for most species of slope rockfish; as a result, stock assessments for slope
rockfish changed little from the previous year. Total ABC for the GOA slope rockfish
complex increased slightly in 1999 to 24,970 t. The ABC for Pacific ocean perch, the most
abundant species, was set at 13,120 t (1% increase). For the other rockfish groups
within the complex, the ABCs remained the same: shortraker/rougheye (1,590 t), northern
(4,990 t), and other slope (5,270 t). Survey age composition data for Pacific ocean
perch in 1996 became available recently and was included in the assessment. These data
verified the presence of a strong 1986 year class. For the first time, age composition
data for Pacific ocean perch and northern rockfish from the commercial fishery are being
collected by observers. These data will help improve the assessments for the species.
The 1999 ABC for GOA pelagic shelf
rockfish (PSR) remained unchanged (4,880 t) from the revised 1998 ABC. The
1998 ABC was revised to adjust for an NPFMC plan amendment which removed blue and black
rockfish from the PSR assemblage. Because of the lack of biological information on pelagic
shelf rockfish, no population dynamics modeling has been done for these species.
Instead, a biomass-based approach based on trawl survey data has been used. Next
years assessment should include updated biomass estimates from the planned 1999
triennial trawl survey, which will likely result in a modified ABC for the assemblage.
By Dave Clausen, Jon Heifetz, John
Karinen, and Mike Sigler.
Effects of
Trawling on Soft-bottomed Ecosystem
A study was conducted 4-17 June 1998
aboard the ADF&G research vessel Medeia using the submersible Delta to
observe the ocean seafloor and to operate a substrate sampler. Two study sites off Kodiak
Island were selected 160 km apart where extensive bottom trawling has occurred adjacent to
areas that are closed to trawling. The purpose of the study was to assess changes to
the seafloor caused by repeated trawling in both open and closed fishing zones.
Specific objectives of the study were to determine if changes have occurred to
infauna, fish, and invertebrate populations, and in substrate characteristics, including
grain-size composition and total organic carbon content.
Twenty four transects were
completed, yielding visual counts and video recordings of fish and invertebrates across 72
km of the seafloor. Each transect was 3,000 m long and bisected the boundary between open
and closed areas. Sediment samples were collected 250 m from the beginning of the
transect, in the middle of the transect, and 250 m from the end of the transect.
Counts of fish and invertebrates
from five of the videos have been completed. Approximately twenty different
categories of fish and invertebrates were quantified, including flatfish,
weathervane scallops, juvenile Tanner crabs, hermit crabs, sea anemones, sea stars, and
sea whips. All sediment samples have been processed for infaunal composition,
sediment grain size, and organic carbon content. Statistical analysis of these data
is under way.
By Ken Krieger and Robert
Stone.
Summary of
Effects of Fishing Gear on Seafloor Habitat in the North Pacific
Major accomplishments of the
AFSCs research on the effects of fishing gear on seafloor habitat during
1996-98 were summarized in the NPFMCs Ecosystems Consideration chapter
in the Councils annual Stock Assessment and Fishery Evaluation Report (SAFE). The
summary titled Current Research on the Effects of Fishing Gear on Seafloor Habitat
in the North Pacific was compiled and edited by Jon Heifetz, ABL, and included
contributions from Linc Freese, Bob Stone, and Ken Krieger of the ABL, Bob McConnaughey
and Harold Zenger of the RACE Division, and Tom Shirley and Cathy Coon of the
University of Alaska Fairbanks. Research projects summarized in the chapter
included:
Effects of Trawling on Seafloor
Habitat and Associated Invertebrate Taxa in the Gulf of Alaska
Retrospective Analysis of
Commercial Bottom Trawl Activity and Benthic Community Structure in the Gulf of Alaska and
Aleutian Islands
Trawl Impact Studies in the
Eastern Bering Sea
A Description of Seafloor Habitat
in a Trawled Region and a Protected Region of the Central Gulf of Alaska
Fishing Impacts on Red-tree Coral (Primnoa
spp.)
Evaluation of Acoustic Technology
for Seabed Classification.
By Jon Heifetz.
Sablefish and
Rockfish Early Life History Studies
Analyses of samples taken for an
ABL-University of Alaska Fairbanks (UAF) cooperative study on larval rockfish
(Sebastes spp.) identification began in 1998. Using mitochondrial DNA techniques, UAF
scientists processed the first group of larval rockfish specimens collected during the
July 1998 cruise of the NOAA ship John N. Cobb. Eight rockfish species were
identified using melanistic pigment patterns. Six rockfish species were identified
genetically. Agreement between the two methods is roughly 33%. Highest agreement
(47%) was in identification of the harlequin rockfish (S. variegatus), the most
abundant species evaluated by both methods.
By Bruce Wing.
Post El Niño
Conditions in Gulf of Alaska
Although the 1997-98 El Niño is
over in the Tropical Eastern Pacific Ocean, warm waters have persisted in the Gulf of
Alaska. For example, during the last 3 months of 1998, sea surface temperatures
monitored at Auke Bay remained 0.5°C to 1.0ºC above the long-term average. Associated
with these warm waters were continuing reports of fishes, birds, and marine mammals
observed either in greater numbers or further north than usual for the fall quarter.
A green sea turtle carcass was found near Yakutat, Alaska, at the end of October.
This is only the ninth green turtle reported from Alaska since 1960; green turtles
are rare north of central California. Gray whales were reported lingering near Kodiak
Island in December. Usually most gray whales have left the Alaskan coast by
mid-October for their annual migration to the lagoons of Baja California. Humpback
whales in southeast Alaska also may have delayed their annual southward migration. A large
number of humpback whales (reported as dozens, fifty", and a
hundred") were observed in the passages near Juneau, Alaska, during late December.
Although a few humpback whales, usually less than a dozen, overwinter in Southeast Alaska,
it is unusual to see large groups of humpback whales remaining in Alaska later than
mid-November. Associated with the humpback whales were red-necked phalaropes
(another unusual occurrence for December) which commonly feed on zooplankton forced to the
surface by feeding whales.
By Bruce Wing.
Changes in Body
Size and Age at Maturity of Salmonid Populations
Ocean Carrying Capacity program
staff sampled chum salmon in fall 1998 from selected streams in Alaska and Washington,
continuing the long-term effort to monitor changes in size and age of North American
salmon populations. Changes in size and/or age at maturity reflect changes in the
ocean environment and the abundance of salmon. Jack Helle, Jerry Pella, and Ellen
Martinson sampled size and age information from chum salmon in the Chilkat River and
Klehini River (Herman Creek) near Haines, Alaska, in mid-October. Helle and
Martinson sampled chum salmon from the Quilcene River in Hood Canal, Washington, in early
December.
By Jack Helle.
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