NOAA logo ond 1998 Quarterly Rpt. sidebar

Auke Bay Laboratory

(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:

  1. installation of remote tracking stations in the Yukon River drainage to record movements of radio-tagged fish

  2. implementation of a large-scale tagging study on fall chum salmon to collect information on run characteristics and fish handling response

  3. implementation of a feasibility study on chinook salmon to assess handling response

  4. 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. tributaries—the Chandalar, Sheenjek, Black, and lower Porcupine Rivers—and 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 system’s 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 Creek’s 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

By John Pohl.

Probing Behavior of Pink Salmon Examined

As a result of the ABL’s 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 O’Clair.

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-on”—hatchery 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 ABL’s 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 Commission’s 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 year’s 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 AFSC’s  research on the effects of fishing gear on seafloor habitat during 1996-98 were summarized in the NPFMC’s “Ecosystems Consideration” chapter in the Council’s 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:

  1. Effects of Trawling on Seafloor Habitat and Associated Invertebrate Taxa in the Gulf of Alaska

  2. Retrospective Analysis of Commercial Bottom Trawl Activity and Benthic Community Structure in the Gulf of Alaska and Aleutian Islands

  3. Trawl Impact Studies in the Eastern Bering Sea

  4. A Description of Seafloor Habitat in a Trawled Region and a Protected Region of the Central Gulf of Alaska

  5. Fishing Impacts on Red-tree Coral (Primnoa spp.)

  6. 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 Niņo Conditions in Gulf of Alaska

Although the 1997-98 El Niņo 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 1.0ēC 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.