(Quarterly Report for April-May-June 1999)
INVESTIGATIONS: Effect of Photoperiod on Overwinter Growth of Underyearling Sockeye Salmon
In previous studies at the Auke Bay Laboratory (ABL), underyearling sockeye fry transferred to salt water following the autumnal equinox grew little or none at all. Sockeye salmon, which normally overwinter in fresh water, have a seasonal cycle in their ability to regulate plasma sodium concentrations during a 24-hour seawater challenge, with declining abilities in fall and winter. In Alaska, declining photoperiod may act as a much stronger cue than temperature, which declines only gradually in the fall in subarctic waters. Due to the large number of endemic underyearling stocks of sockeye salmon that migrate directly to sea following emergence, Alaskan hatcheries are exploring the feasibility of fall transfer into net-pens of hatchery-reared fry. What is the best time for saltwater entry and what factors influence that timing?
Groups of underyearling sockeye salmon (~2 g) were introduced into saltwater tanks 2 weeks prior to the fall equinox, during the equinox, and 2 weeks following. All groups were reared for 8 months (September-May) in saltwater tanks to determine the relative effects of photoperiod, salinity (20 and 30 ppt), and temperature (4E and 8EC) on overwinter growth. Growth in all groups fell from greater than 2 percent body weight per day (BWD) to less than 0.5 percent BWD following the equinox, but there was no differences in overwinter growth due to entry timing. Fish transferred to reduced salinity (20 ppt) prior to the equinox had significantly better initial growth than fish transferred directly to salt water at the same time. This differential in growth did not persist past the winter solstice. Fish reared at 4EC had virtually no overwinter growth in contrast to a growth rate of 0.3-0.5 percent BWD among fish held at 8EC. These data suggests that photoperiod and salinity are important variables influencing overwinter growth of underyearling sockeye salmon in salt water.
By Adam Moles.
Exxon Valdez Oil Spill Studies Continue
Field work was initiated early in the field season with several rounds of sampling of mussels from oiled mussel beds in Prince William Sound and for pristane as an index of copepod abundance.
Also, over 175,000 pink salmon fry were marked and released at the Little Port Walter field station as part of a long-term oil exposure experiment designed to test long-term effects of oil exposure on reproductive viability when these fish return as adults in fall 2000. In September 1998, 200,000 pink salmon eggs were fertilized and incubated in water contaminated by percolating through gravel coated with Alaska North Slope crude oil. Incubators with uncontaminated gravel were paired with those containing two other exposure levels, the highest of which was equal to the Alaska State Water Quality Standard. In May, over 175,000 survivors were marked and released, so that returning adults can be identified and spawned. The objectives of this study are to confirm field observations of reduced reproductive ability resulting from embryonic exposure to oil. In addition, long-term effects on marine survival and growth will be correlated with the activities of biomarkers such as histopathological damage and cytochrome P450-A1A activity observed when fry were emerging from incubators.
By Jeep Rice.
New Web Page
The AFSC/ABL Exxon Valdez Oil Spill web pages have been updated and expanded. The site provides information on current Exxon Valdez Oil Spill (EVOS) Trustee Council-funded projects, reports, posters, and a bibliography produced by Habitat Program researchers.
By Mandy Lindeberg.
NOAA/HAZMAT Cooperative Field Study
The ABL participated in a 2-week cooperative NOAA- HAZMAT (Hazardous Materials) field study in Kachemak Bay, Alaska, to assist researchers with algae identification and to initiate groundwork on an algal field guide.
Study objectives include enumeration of existing epibiota study sites, a new Fucus recovery/senescence study, preliminary scoping for infauna/grain size study, and a preliminary algae field guide project. Major efforts on the algae field guide involved sample collection, herbarium production, and field/laboratory photography for incorporation into a prototype field guide (digital and hardcopy). The field guide will describe marine macro algae of the Kachemak Bay habitat and will serve as an aid for researchers and an educational tool for students.
The study represents the first official NOAA use of the Kasitsna Bay Laboratory since Kasitsna Bay was designated a National Estuarine Research Reserve last year. As an undisturbed habitat, Kasitsna Bay will provide a baseline for years to come against which disturbed habitat such as Prince William Sound can be assessed.
By Mandy Lindeberg.
Duck Creek Selected as Showcase Watershed
Duck Creek has been selected as a National Showcase Watershed for demonstrating stream corridor restoration. The Showcase program is a key part of the Clean Water Action Plan announced in 1998. In May 1999, the Federal Interagency Stream Restoration Working Group, representing 15 Federal agencies, selected Duck Creek as 1of 12 watersheds in the Nation to be showcased for stream corridor restoration activities. Activities in each of the 12 watersheds will be nationally publicized to increase public awareness and promote the use of the concepts outlined in the Working Group publication (October 1998) Stream Corridor Restoration: Principles, Processes, and Practices". K Koski and Mitch Lorenz will contribute content for an internet site being set up by the Working Group. The Duck Creek Watershed Management Plan will also be nationally publicized as part of the Clean Water Action Plan.
By K Koski.
Restoration Projects Proposed for Duck Creek
The U.S. Army Corps of Engineers (COE) has proposed eight restoration projects in the Duck Creek watershed to be funded through a habitat restoration program under Section 206 of the Clean Water Act. The projects are planned over a 5- year period at an estimated cost of $5.2 million. The COE proposal, based on projects outlined in the Duck Creek Watershed Management Plan, was supported by the City-Borough of Juneau (CBJ). A letter of intent was filed by CBJ to help sponsor the 35 percent match required by the projects.
By K Koski.
OCEAN CARRYING CAPACITY: Survey of Salmon in Northeastern Pacific Ocean
During May 1999 ABL scientists conducted a survey of ocean distribution of immature and maturing salmon along the 165E and 145EW longitude meridians across the known southern limits of salmon distribution, on the high seas of the Northeastern Pacific Ocean. The work is part of a cooperative international effort coordinated by the North Pacific Anadromous Fish Commission to examine distribution, growth, and survival of Pacific salmon during their ocean life. The cruise covered over 4,000 nautical miles (nmi) and was carried out on the chartered fish vessel Great Pacific, a 38-m stern trawler. Sampling gear was a midwater rope trawl towed near surface at 5 kts., with typical spread to 18 m depth and 52 m width. Salinity-temperature profiles were measured with a CTD (conductivity-temperature-depth) meter following each tow. The survey departed from Dutch Harbor on 3 May and began sampling nearshore on the Bering Sea and North Pacific sides of Unalaska Island, then proceeded south along the 165EW longitude line to lat. 38EN, ran east to long. 145EW , worked north to the Cape St. Elias vicinity, and ran to Kodiak to disembark scientists on 24 May. With 56 successful tows completed, the total catch of salmon was 1,159 fishes, including 501 immature and 658 maturing salmon. No juvenile (age-0) salmon were taken. Immature salmon included 236 chum, 246 sockeye, and 19 chinook. Maturing salmon included 253 chum, 196 sockeye, 185 pink, 22 coho, and 2 chinook. The survey took 521 salmon from Unalaska Island down long. 165EW, and 638 salmon along long. 145EW. A total of 62 salmon were tagged during the cruise, 34 with archival (thermal) tags and 28 with standard disc tags only. Thermal tags were placed on 24 sockeye, 8 chum, and 1 each coho and chinook. Standard disc (only) tags were placed on 17 sockeye, 10 chum and 1 chinook. Two tags were later recovered. One thermal tagged chum salmon released near lat. 56EN, long. 145EW, was recovered a month later 700 nmi west in Unimak Pass. One sockeye with thermal tag that was released near lat. 5EN, long. 146EW was recovered 24 days later in Chignik Lagoon, over 500 nmi west.
A primary finding of the survey was that salmon of all species and age groups were discretely distributed on the high seas, with little evidence of any mixing or nearby occurrence. Other fishes taken on the cruise included walleye pollock, Pacific cod, rockfish, sablefish, daggertooth, lancetfish, king-of-the-salmon, lanternfish, Pacific pomfret, smooth lumpsucker, spiny dogfish, salmon shark, blue shark, Pacific lamprey, and unidentified specimen, possibly a little known deepsea group, resembling the Melamphaidae or Diretmidae. Invertebrates in catches included salps, scyphozoan medusas, and squid. Sea surface temperatures ranged from 3.8EC at Cape Cheerful in the eastern Bering Sea to 14.4EC along the 38EN line at 157E long.
By Dick Carlson.
GROUNDFISH INVESTIGATIONS: Adaptive Sampling Study of Rockfishes in the Gulf of Alaska
A Sea Grant Partnership Grant study initiated by the ABL and the University of Alaska Fairbanks (UAF), Juneau Center for Fisheries and Ocean Science (JCFOS), began 12 June in Seward, Alaska, aboard the chartered fishing vessel Unimak and was scheduled to finish on June 29. This is the second year of a 2-year grant to UAF-JCFOS to investigate a new sampling design for slope rockfish (Sebastes spp.) adaptive sampling. Data are also being collected to help determine sampling protocols in the NMFS fishery observer program. Scientists from UAF, and the AFSCs ABL, Resource Assessment and Conservation Engineering Division (RACE), and Resource Ecology and Fisheries Management Division (REFM) have participated in the preparation, planning and field data collection.
Presently, Center scientists rely on results from bottom trawl surveys that use stratified random sampling to determine estimates of abundance (biomass) for various groundfish species. Random sampling is suspected to be inefficient in estimating abundance of species that aggregate in localized areas. Biomass estimates for rockfish often show large fluctuations from survey to survey which do not seem reasonable given the slow growth and low natural mortality rates of all Sebastes species.
Adaptive sampling is a relatively new technique which, to date, has seldom been used in fisheries applications. However, it appears to be particularly appropriate for sampling populations with a clustered distribution, such as that observed for many rockfish species. In adaptive sampling, random or systematic sampling is initially used to locate concentrations of the targeted species, and is then followed by intensive sampling in the vicinity of the concentrations.
This study is focused on three commercially important species of slope rockfish: Pacific ocean perch (Sebastes alutus) (POP), shortraker rockfish (S. borealis), and rougheye rockfish (S. aleutianus). The net used was equipped with tire gear to facilitate trawling over rough substrate, and the vessel was allowed to retain the catch to partially defray the costs of the charter. The experiment is being conducted in the West Yakutat area in the eastern Gulf of Alaska. The study area covers the upper continental slope to a depth of 500 m.
Participants on the cruise from ABL were Dave Clausen, Jon Heifetz (co-principle investigator), Chris Lunsford, Pat Malecha, Dean Courtney, and Dave Csepp; from UAF were Professor Terry Quinn (co-principle investigator) and graduate students, Dana Hanselman and Andrew Matala; and from the AFSC Observer Program, Sandi Neidetcher. Sampling during the cruise was scheduled for 24 hours per day with Heifetz and Clausen as alternating field party chief.
1999 Sablefish Longline Survey Underway
The 1999 sablefish longline survey began 28 May in Dutch Harbor, Alaska. This was the twenty-first annual standard longline survey. The survey is conducted by the Centers ABL and RACE Divisions and covers the Gulf of Alaska annually and the Bering Sea and Aleutian Islands in alternate years. The survey charter fishing vessel Ocean Prowler sampled Bering Sea stations during the first leg. During the second leg, the vessel will finish the Bering Sea and Western Gulf stations, then transit the Gulf of Alaska, conduct seamount sampling, and port in Ketchikan. The survey will then begin at Dixon Entrance and progress westward to complete the Central Gulf Area around 3 September. Chief scientist for the first leg was Larry Haaga of the RACE Division, and Nancy Maloney of the ABL is the chief scientist on the second leg.
The survey catch rates are critical in the determination of the annual Allowable Biological Catch (ABC) of sablefish. In addition to indexing sablefish abundance, sablefish, shortspine thornyheads, and Greenland turbot will be tagged and released with Floy anchor tags during the survey. Length-weight data and otoliths are collected from sablefish. A surface gillnet will be deployed at night to sample juvenile sablefish (ages 0 and 1). Sightings of short tail albatross will be recorded.
Age-structured Model for Gulf of Alaska Northern Rockfish
The northern rockfish, Sebastes polyspinis, is one of the most abundant and commercially valuable members of its genus in Alaska waters. As implied by its common name, this fish has one of the most northerly distributions among the more than 60 species of Sebastes in the north Pacific. Bottom trawl surveys of the Gulf of Alaska and Aleutian Islands region indicate that northern rockfish is the second most abundant rockfish species in these regions, surpassed only by Pacific ocean perch (S. alutus). Since 1990, northern rockfish has supported a valuable domestic trawl fishery in Alaska. For the Gulf of Alaska region alone recent catch levels have been around 5,000 metric tons (t); gross wholesale value of this fishery was estimated at $4 million in 1995.
The stock assessment of northern rockfish used to recommend catch quotas has relied almost entirely on biomass estimates provided by NMFS trawl surveys. The recent Rockfish Stock Assessment Review conducted by an outside review team expressed concern about the reliability of survey biomass and the use of average survey biomass as the estimate of exploitable biomass for many of the rockfish stocks. The review team specifically recommended attempting age-structured assessments of northern rockfish to improve the quality of the stock assessment. Age-and-length composition data are available from the surveys and length composition data are available from the fishery. Otoliths were taken from the 1998 fishery for age composition data.
In FY98 the AFSC Rockfish Working Group funded a contract to construct an age-structured stock assessment model for northern rockfish, incorporating fishery catch data, survey abundance indices, survey age compositions, and survey and fishery length compositions. Programming of the model has been completed and initial testing indicate validity of basic model structure and program coding. The model was constructed using AD Model Builder computer software. The model now will be further tested and evaluated prior to actual application in the determination of northern rockfish ABC recommendations.
Fishery Data Evaluated For Incorporation in Sablefish Assessment Model
Since 1979, annual longline surveys have been conducted on the upper continental slope in the Gulf of Alaska, Aleutian Islands, and eastern Bering Sea. Data from these surveys are a major component used in computing relative population indices for sablefish. Steady declines in survey catch rates of sablefish have led to reduced fishery quotas in recent years. Concern has been expressed that fishery catch rates have remained strong in some areas despite the apparent decline of sablefish populations seen in the survey. Extensive fishery information is available through data collected by the domestic observer program. However, fishery catch rates may not be representative because gear configurations and fishing patterns may vary. Fishermen also target concentrations of fish, even as geographic distribution shrinks when abundance declines. A draft report calculating preliminary CPUEs for the fishery and comparing them to the survey information is under review.
In Situ Studies on Alaskan Coral
Colonies of the gorgonian coral (Swiftia sp). were located during cruise 99-07 aboard the NOAA ship John N. Cobb which was completed 4 June. Numerous colonies were found at sites near Tenakee Inlet and the Little Port Walter field station. These sites will be revisited during cruise 99-10 in July, and divers will deploy long-term temperature recorders, collect baseline size measurements of individual colonies, and deploy a variety of potential settling substrate types. This may provide opportunities for growth, recruitment, and habitat studies that could lead to new insights into the biological requirements and longevity of corals. Although the primary cruise mission of finding red tree coral (Primnoa sp.) within safe scuba depths was not successful, sites along the gulf coast of Prince of Wales Island will be explored during cruise 99-10 in July in hopes of finding shallow water colonies of that species where similar studies can be initiated.
By Phil Rigby.
MARINE SALMON INTERACTIONS: Bear and Firearms Safety
The ABL has developed a training program for its employees doing field work in areas with high brown and black bear concentrations. Also, policy has been established at permanent field stations to minimize the interaction of local bears and field personnel. The policy involves minimizing man-made attractors and using aversive conditioning to keep bears away from high human-use areas.
The training program covers a range of topics from basic identification, species and sex differences, to bear behavior and avoidance techniques. Training materials include video and written information from the U.S. Forest Service, the Canadian Ministry of Forestry, the Alaska Department of Fish and Game, and the National Rifle Association.
Basic firearms safety instruction and rifle/shotgun training are given by an N.R.A. instructor. Yearly qualification is required for field personnel who need to carry firearms. In the past, instruction was given by private instructors on their own time or by individuals from other agencies. The instruction is now given by ABL staff certified by the N.R.A. The emphasis of the firearms training is safety. During annual certification staff must demonstrate safe gun handling and marksmanship. The goal of the training is to educate and inform personnel in order to minimize negative bear encounters and to promote safe and responsible gun handling in the field.
By John Joyce.
ESA Steelhead Research
Research at ABLs Little Port Walter field station is being conducted to determine long-term effects of inbreeding depression (genetic damage caused by the breeding of related individuals) that typically occurs in small, remnant populations of animals that frequently have been placed in captivity for protection. Various techniques are currently being tested in captive populations of many different endangered animals in many parts of the world. The techniques span the range of human involvement from complete control of breeding by maintaining complete pedigrees and identities of all individuals in the population with controlled, artificial culture of offspring to quasi-natural methods which provide a natural setting and as near normal breeding interactions and natural rearing of offspring as possible under a protective protocol. One method being considered for preserving important genetic resources of critically endangered anadromous steelhead populations is to sequester a portion of the at risk population throughout its life cycle in a natural freshwater environment that can be protected, for perhaps decades, until its natural habitat has been restored. The population would be allowed to reproduce naturally, however, the ocean migratory phase would be curtailed.
Scientists at the Little Port Walter station are testing the effects of 70 years of freshwater sequestration, using populations of steelhead that were stocked into fishless lakes with natural migration barriers during the 1920s and 1930s, on important life history characteristics such as genetic variability, bilateral asymmetry, spawning timing, development rate, growth rates, survival in captive and wild environments, age at maturity, smolting rates, and marine survival.
To date, more than 200 families of anadromous steelhead and resident rainbow trout and their crosses have be created and studied. Over 6,000 fish from 74 families are being cultured in captivity to maturity and over 20,000 coded-wire-tagged smolts have been released. Preliminary indications are that steelhead populations that have been held completely in fresh water for 70 years can still produce significant, although fewer, numbers of smolts as their ancestral stock. It is still unknown if marine survival rates of the smolts differ however. Significant genetic differences exist between the sequestered and ancestral populations, however, information is still being analyzed to determine if the differences were caused by the long period of sequestration or the original establishment of the freshwater population.
By Frank Thrower.