(Quarterly Report for Jan-Feb-March 1999)
Research Redefines Oil Toxicity Paradigms About Oil and Fish
Research by ABLs Habitat Program over the past decade has produced a new perspective on the toxicity of oil to fish. In the 1970s, ABL researchers determined that crude oil in water was toxic to fish at concentrations of 1-4 parts per million (ppm). This research was the basis for water quality standards for oil in Alaskan waters, the most stringent standards in the United States. Research by ABL scientists in the 1990s, however, now indicates that oil is much more toxic to fish than previously believed. Instead of toxicities in the ppm range, ABL research has observed toxicities in the parts per billion (ppb) range.
These new understandings about oil and its effect on fish have evolved from a suite of long-term studies of the Exxon Valdez oil spill. First, the Alaska Department of Fish and Game (ADF&G) measured elevated salmon egg mortalities in oiled salmon streams in Prince William Sound (PWS) for 4 years following the spill. The egg mortalities represented new damage from persistent oilan unprecedented finding compared to other oil spills. ABL field efforts in 1995 detected significant quantities of oil alongside streams in PWS. Stream deltas had not been cleaned in 1989 because it was thought that cleaning would cause physical damage to the spawning habitats of salmon. Oil was not expected to invade spawning redds in significant quantities and was not expected to persist. By the mid-1990s, oil continued to be detected in a variety of habitats in PWS, and chemical fingerprinting of the compounds continued to identify the source as the 1989 Exxon Valdez oil spill. Further, chemical fingerprinting also identified the persistent fractions of oil as being predominantly the heaviest ringed aromatic components of crude oil and also the most toxic.
The sensitivity of eggs to low concentrations of this persistent oil fraction was confirmed in a series of long-term tests conducted at ABLs Little Port Walter Field Station. Deformities were readily evident in emergent fry which had been exposed months earlier as eggs to ppb concentrations of PAHs (polynuclear aromatic hydrocarbons). Sensitivity to oil concentrations this low was unprecedented, but these toxic fractions had never been used in prior long-term tests. The long-term effects were also surprising: normal-looking fry from eggs exposed to oil were tagged and released to the marine environment, and delayed effects on growth and survival were measured when the adults returned to their natal watershed. Of adults exposed as eggs to 19 ppb total PAH, 40% fewer than controls returned a year later.
The ABLs oil toxicity studies have far-reaching relevance, particularly for urbanized watersheds and estuaries of the coastal United States. In urbanized waterways, many coastal habitats have continuous input of hydrocarbons due to runoff as development continues. Of the 9,692 miles of United States coastline outside Alaska, over two-thirds are considered urban. Studies in the literature estimate that, on a per capita basis, the United States spills, on average, about a quart of oil per person per year. Fifty million people spill more than 12 million gallons of oil per year, which is equivalent to the Exxon Valdez spill. Unfortunately, that quantity is spilled this year, next year, and the years following. Given the high toxicity of PAHs to eggs, chronic input of hydrocarbons into streams, bays, and estuaries may limit recruitment of fish populations far more than was previously supposed.
By Jeep Rice.
Science Symposium Marks Tenth Anniversary of Exxon Valdez Oil Spill
The 10th anniversary of the Exxon Valdez oil spill was marked by a symposium in Anchorage, Alaska, on 23-26 March. The symposium was sponsored by the Oil Spill Trustee Council to present the results of 10 years of Federal and state research on the effects of the 1989 spill in Prince William Sound. The results of 13 ABL studies (see 1995/95 and 1996/97 AFSC Biennial Reports for detailed discussions) were presented. Two AFSC scientists from the Auke Bay Laboratory chaired technical sessions: Jeep Rice on Long Term Effects to Salmon and Jeff Short on Fate of Oil. The results of the Trustees research was critical to answering questions concerning long-term persistence of oil, toxicity effects at parts-per-billion (not parts-per-million, as previously assumed) concentrations, and sensitivity to oil at different life stages of marine organisms in Prince William Sound. The results of the ABL studies are relevant not only to Alaska and Prince William Sound, but also to other areas where chronic oil discharges (such as parking lot run-off) can enter water bodies that provide habitat for vulnerable life stages of aquatic organisms. Because they could lead to regulatory changes, these studies have national significance and have attracted national attention from both the media and scientists.
By Jeep Rice.
Green Sea Urchin Growth Rates Studied
Using an analytical protocol developed in the ABLs Image Analyses Laboratory, growth rate measurements from calcein-
marked green sea urchin jaws were successfully completed on a total of 120 marked urchin jaws recovered from a sample of 1,382 jaws examined. This study, part of a larger project led by the U.S. Geological Survey (USGS) to research the recovery of near-shore vertebrate predators injured by the Exxon Valdez oil spill, relates to the influence of oil on green sea urchin growth. The purpose of the study was to see if there is a relation between sea otter populations feeding on urchins at oiled and unoiled sites in Prince William Sound.
Investigators from Coastal Resource Associates of Vista, California, initially marked groups of urchins in 1997 from oiled and nonoiled sites in Prince William Sound by immersion in solutions of calcein. The calcein is then metabolized and deposited in the calcified parts of the urchin. Urchins were then returned to the collection sites. Later, researchers collected random samples of urchins from both locations and prepared jaws for analyses. These samples were examined under ultraviolet-equipped microscopes in ABLs Image Analyses Laboratory to identify flourescent calcein marks (which appear as bands) and to measure growth of the urchins with a computerized digitizer equipped with a low-light ccd (charge-coupled device) video camera.
Percentages of marked urchins analyzed at the ABL in eight blind sample lots provided by Coastal Resource Associates ranged from 0% in one lot to 40.0% in another. Measurements of total jaw length and distance from end of jaw to the calcein mark (growth since marking) were recorded from each marked urchin jaw. Hard copies of total length and mark distance were made from annotated digital images. Soft copies of these images were saved to zip disks. In addition, total jaw size measurements and distance to mark measurements were saved to a database provided by Coastal Resource Associates. All data, photos, and samples were returned to Coastal Resource Associates for further data analysis. This program was supported by the USGS and Coastal Resource Associates to fund a technician to help detect and measure marked urchins. Results are pending analysis by Coastal Resource Associates scientists.
By Donald Mortensen.
Effects of Domestication On Predator Avoidance, Growth, Predation Success, and Marine Survival in Stocks of Chinook Salmon
The state of Alaska has sought to decrease negative effects of salmon enhancement by establishing a genetic management policy that minimizes hatchery and wild stock interaction by regulating hatchery siting and stock transfers. However, domestication within the hatchery may still cause divergence from the wild donor population. In response to increasing concern about the genetic effects of cultured salmonid fishes on natural populations, ABLs Marine Salmon Investigation program is conducting a series of experiments using stocks of chinook salmon native to Southeast Alaska. Experiments include research projects designed to examine the effects of domestication, if any, on Alaskan spring chinook stocks. Performance of fourth generation progeny from two hatchery stocks of chinook salmon at Little Port Walter are being compared with the offspring of wild chinook from the same donor stocks. These studies should provide valuable information regarding the nature and degree of domestication selection in these populations.
Parallel studies will be conducted on these two spring chinook stocks. The Little Port Walter Hatchery Chickamin River stock resulted from a small collection of broodstock in 1976 (eight females, nine males). The LPW Unuk River stock was also started in 1976, but has had periodic infusion of wild gametes. Comparisons are being made between the hatchery stocks and the progeny of wild chinook collected from the Chickamin in 1996 and the Unuk in 1998. Our first experiment is a series of experimental trials to measure the ability of hatchery and wild chinook salmon to avoid predation by Dolly Varden char. The second experiment evaluates differences in freshwater culture performance, including presmolt survival and growth, in the hatchery environment. The third experiment examines smolt predatory efficiency. The final evaluation will be the measurement of marine survival, and size and age at maturity of coded-wire tagged smolts from hatchery and wild groups.
The results of the Chickamin River predation trial indicate no significant differences between groups in the ability to avoid predation in the testing environment. Results of the freshwater performance trials show similar growth and survival rates among groups through smolting. No results are yet available on the predatory efficiency of smolts. Final data on the marine performance will be collected over the next 7 years. The Unuk River study, initiated in 1998, will follow a similar design with predation trials, culture performance experiments, and the release of coded-wire tagged smolts. We hope to expand this work to include other testing environments and more chinook salmon stocks currently used for enhancement in Southeast Alaska.
By John Joyce, Alex Wertheimer, and John Thedinga.
Survival and Straying of Pink Salmon Measured Using Recoveries of Coded-Wire Tags and Thermally-Induced Otolith Marks
Pink salmon fry (1994 brood-year) from Auke Creek, Alaska, were marked with coded-wire tags (CWT) and thermally-induced otolith marks to investigate the effects of tagging on survival and straying, and to estimate straying rates to local watersheds. Fish having both CWT and marked otoliths had significantly lower survival than did untagged, otolith-marked fish. There was no difference in survival rates between fish both tagged and otolith-marked and the wild fry with CWT only. Early-run pink salmon had lower observed straying rates than did late-run fish. Straying of CWT fish was not significantly different than that of otolith-marked fish. We were able to document movement of pink salmon between Auke Creek, Gastineau Hatchery, and other streams within a 14-km radius of Auke Creek.
By Donald Mortensen, Alex Wertheimer, Jacek Maselko, and Sidney Taylor.
ABL Sablefish Tag Recovery Program
Processing sablefish tag recoveries and administration of the reward program continued during 1998. About 710 tags for 1998 have been received so far, compared to a total of 732 in 1997.
As in 1997, about 39% of the fish recovered in 1998 had been at liberty for more than 10 years. The four fish at liberty the longest were all tagged in Chatham Strait, southeastern Alaska, in 1973 and recovered in Chatham Strait in 1998. Tagging continued on the 1998 NMFS sablefish longline survey, with 3,495 adult sablefish tagged and released.
Otoliths from six known-age sablefish (i.e., fish tagged with anchor tags as juveniles) were recovered during 1998, bringing the total otolith collection of these fish to 87. A manuscript describing the initial findings of this study was accepted for publication by Fishery Bulletin in 1998.
Otoliths from two more oxytetracycline (OTC)-marked fish were recovered during 1998; in all, otoliths have been collected from 70 of these fish since the marking was done in 1988. We are hoping to begin reading these otoliths this year.
Sablefish tags recovered during the 20 years of cooperative and domestic longline surveys are being used to estimate the commercial tag reporting rate. Return rates of research and fishery-caught tags are compared, with the assumption that all research-caught tagged fish are observed (reported). So far it appears that the reporting rate over all areas and years is about 30%.
By Nancy Maloney.
Adaptive Sampling of Slope Rockfish in the Gulf of Alaska
Preliminary results are now available for an experimental bottom trawl survey of slope rockfish conducted in August 1998. This experiment, which used the chartered factory trawler Unimak Enterprise in the Gulf of Alaska northeast of Kodiak Island, was a cooperative effort between scientists of ABLs Groundfish Assessment program and the University of Alaska Fairbanks, Juneau Center, School of Fisheries and Ocean Sciences. The study was directed at three important commercial species: Pacific ocean perch, shortraker rockfish, and rougheye rockfish. Methods of this study were first reported in the July-August-September 1998 issue of the AFSC Quarterly Report.
Briefly, the studys objective was to determine if a new survey methodology, adaptive sampling, would provide improved estimates of abundance for slope rockfish when compared with simple random sampling, which has been the standard design for all previous trawl surveys of rockfish in this region. Adaptive sampling is a technique not widely used in fisheries, but previous research has indicated that for clustered populations, such as those observed for many rockfish species, it may have benefits over simple random sampling. The experiment focused on two study areas which were divided into strata, and each stratum was initially sampled by conducting bottom tows at random locations. This was followed by an adaptive phase, in which a systematic pattern of closely spaced tows was made around the random tows in each stratum that showed high catches of rockfish. Estimates of rockfish abundance were computed for each stratum based on just the random tows, and also on two adaptive estimators that incorporated data from both the random and the adaptive tows. Contrary to initial expectations, preliminary adaptive sampling results for Pacific ocean perch showed only modest gains in the precision of abundance estimates when compared with random sampling. These results, however, appeared to be highly dependent on the stratification pattern that was used. For shortraker and rougheye rockfish, adaptive sampling found a substantially larger abundance in one stratum than did random sampling, whereas in the other stratum, the two methods showed almost identical results. Further studies on the efficacy of adaptive sampling for surveying rockfish abundance will be conducted in June 1999 using a chartered trawler off Yakutat, Alaska.
By Dave Clausen.
NPAFC Symposium Planned
The North Pacific Anadromous Fish Commission (NPAFC) Symposium Recent Changes in Ocean Production of Pacific Salmon will be held in Juneau on 1-2 November 1999 following the NPAFC annual meeting also held in Juneau this year. The symposium committee, including Dr. Y. Ishida from the Fisheries Agency of Japan, Dr. V. Radchenko from TINRO in Vladivostok, Russia, Dr. D. Noakes from the Department of Fisheries and Oceans in Nanaimo, British Columbia, and Dr. J. Helle (Chairman) from the Auke Bay Laboratory, met in Vancouver during the research coordination meetings in March to select oral and poster presentations from submitted abstracts. Up to six oral presentations from each country were selected and more than 40 posters were approved.
By Jack Helle.