JFM99 Quarterly Rpt. sidebar
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(Quarterly Report for Jan-Feb-March 1999)
ABL
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.
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