Cetacean Necropsies to Determine Injury from the Exxon Valdez Oil Spill
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Exxon Valdez Oil Spill State/Federal Natural Resource Damage Assessment Annual Report Cetacean Necropsies to Determine Injury from the Exxon Valdez Oil Spill Marine Mammal Study Number 3 Annual Report This annual report has been prepared for peer review as part of the Exxon Valdez Oil Spill Trustee Council restoration program for the purpose of assessing project progress. Peer review comments have not been addressed in this annual report. on Reserve Thomas R. Loughlin Alaska Fisheries Science Center National Marine Mammal Laboratory 7600 Sand Point Way N. E., BIN C15700 GC Seattle, Washington 98115 1552 .P75 E99 MM-3 October 1994 no.3 \MIIIIIUDiiiiiiiiiiiiiUI\1 3 3755 000 10885 2 "The Exxon Valdez Oil Spill Trustee Council conducts aJI programs and activities free from discrimination, consistent with the Americans with Disabilities Act. This publication is available in alternative communication fonnats upon request. Please contact the Restoration Office to make any necessary arrangements. Any person who believes she or he has been discriminated against should write to: EVOS Trustee Council, 645 G Street, Suite 401, Anchorage, AK 99501; or O.E.O. U.S. Department oflnterior, Washington, D.C. 20240." n Y },.RLlS ~REsoURCES LmkM LIBRARY & lNPORiWATtON SERVICBS Jl s· 3150C STREET, SumslOO AN~h , ANCHORAGE,~ 99503 G-s 1S'Sl f!C I PI) {,&f6~ Exxon Valdez Oil Spill v~ " ·. ( State/Federal Natural Resource Damage Assessment Annual Report l""'i I a,.. Cetacean Necropsies to Determine Injury from the Exxon Valdez Oil Spill Marine Mammal Study Number 3 Annual Report This annual report has been prepared for peer review as part of the Exxon Valdez Oil Spill Trustee Council restoration program for the purpose of assessing project progress. Peer review comments have not been addressed in this annual report. J ) Thomas R. Loughlin Alaska Fisheries Science Center National Marine Mammal Laboratory 7600 Sand Point Way N. E., BIN Cl5700 Seattle, Washington 98115 October 1994 ... • Cetacean Necropsies to Determine Injury from the Exxon Valdez Oil SpiU Marine Mammal Study Number 3 Final Report r1 '!<I Stud7 Bistocy: Marine Mammal Study Number 3 was initiated in 1989 to locate and count cetaceans stranded from Kayak Island through Bristol Bay, Alaska, and to conduct necropsies on each animal to collect tissue samples, determine if the stranded cetacean came into contact with Exxon Valdez oil, and determine if the cetacean died as a result of contamination from Exxon Valdez oil. Due partly to the difficulty of collecting tissue samples from dead and decomposing ·cetaceans and partly to the inconclusive results from the first year of study, Marine Mammal Study Number 3 was not continued beyond 1989/90. The results of this one year of study were presented in a book chapter: Loughlin, T.R. 1994. Tissue hydrocarbon levels and the number of cetaceans found dead after the spill. Pages 359-370 in T.R. Loughlin, ed. Marine Mammals and the Exxon Valdez. Academic Press, San Diego. ,, The text of this chapter is reproduced here as the body of the final report on Marine Mammal Study Number 3. The author and the Exxon Valdez Oil Spill Trustee Council gratefully acknowledge the permission of Academic Press to reproduce this material. Abstract: Over 9,600 miles of coastline were surveyed. Thirty-seven dead cetaceans were located, including: 26 gray whales, 5 harbor porpoise, 3 unidentified, 2 minke whales, and I fin ·~· ~ whale. Nearly all of the specimens were moderately to very decomposed, which roughly corresponds to several weeks to months postmortem. Double-counting may have occurred in three cases in which beached cetaceans moved by current and tides from one beach to the next. Only seven animals were in satisfactory condition for tissue collection and analysis: three gray whales, three harbor porpoise, and one minke whale. Results from the necropsies, chemical analyses of tissues, or histological examinations provide no indication of the causes of death for the sampled cetaceans. The large number of stranded gray whales (n=26) was attributed to the timing of the search effort, which coincided with the northern migration of gray whales, I augmented by increased survey effort in the study area associated with the oil spill. Ke7 Words: cetacean, gray whales, Eschrichtius robustus, fin whale, Balaenoptera physalus, ' minke whale, Balaenoptera acutorostrata, harbor porpoise, Phocoena phocoena, Gulf of Alaska. Exxon Valdez oil spill. Project Data: All data gathered for this project are presented in the final report. However, the original reports on the laboratory analysis of cetacean tissue samples are in files maintained by Dr. Thomas R. Loughlin at the National Marine Mammal Laboratory, 7600 Sand Point Way N.E., BIN C15700, Seattle, Washington 98115. Citation: Loughlin, T.R. 1994. Cetacean necropsies to determine injury from the Exxon Valdez oil spill. Exxon Valdez Oil Spill State/Federal Natural Resource Damage Assessment Final ,, Report (Marine Mammal Study Number 3), U.S. Department of Commerce, National Oceanic and Atmospheric Administration, National Marine Fisheries Service, Alaska Fisheries Science Center, National Marine Mammal Laboratory, Seattle, Washington. • i I • ••=~ ·I :II Iii ... • :Ir • • ..,,~ • ..... ,.. llli .,, .. • lilt 1111! Chapter 20 '" '~ Tissue Hydrocarbon Levels and the Number of Cetaceans Found Dead after the Spill Thomas R. Loughlin t - INTRODUCTION Nineteen species of cetaceans occupy marine habitats in the Gulf of Alaska ,. (Calkins 1986). Of these, fm (Balaenoptera physalus), sei (Balaenoptera bore alis), minke (Balaenoptera acutorostrata), humpback (Megaptera novaeangliae), .. gray (Eschrichtius robustus). and killer whales (Orcinus orca), and Dall's (Pho coenoides dalli) rutd harbor porpoise (Phocoena phocoena) are often encountered ,,. in waters affected by the Exxon Valdez oil spill (EVOS). Baleen whales are most vulnerable to the effects of an oil spill due to their generally low numbers. peculiar feeding mode (such as at the surface or on the I ',~ bottom of the ocean nearshore), and dependence on selected, localized habitats for feeding and reproduction (Wfirsig 1990). Nearly the entire population of eastern Pacific gray whales migrate along Alaska· s coast each March through May en route to summer feeding grounds in the Bering and Chukchi Seas (Braham 1984 ). Some gray whales apparently feed in Alaskan waters during their northward migration (Brnham 1984), and others are known to remain in the Gulf of Alaska throughout the sununer (Nerini 1984). They rarely enter Prince William Sound (PWS). Gray whale carcw;scs are routinely seen along the north coast of the Alaska Peninsula each spring. a presumed result of natural mortality. By mid-May 1989, four carcasses were found at Tugidak. Island, south of Kodiak Island. These fmdings increased concern about the possible impact of the spilled oil on gray whales and other cetaceans and prompted this study to: (1) locate and count stranded cetaceans from Kayak Island through Bristol Bay and if possible conduct necropsies on each carcass and collect tissue samples for chemical analysis; (2) detennine if exrunined carcasses recently crune in contact with oil. in particular Exxon Val de: crude oil: and (3) detennine if stranded cetaceans died as a result of crude oil contamination. j Marine Mammals and the Exxon Valdez 359 360 ·1·. Lougnttn METHODS "' Aerial surveys were used to search for stranded cetaceans on 13 J w1e and from 23 to 30 June 1989. Surveys were flown from Kayak Island north to PWS, along all coa'itlines and island groups west to Cape Sarichef, and east to King Salmon in ''" Bristol Bay. Unscheduled surveys occurred from March to October and concen ~·· ll-ated in PWS. Surveys were conducted in single- or twin-engine float planes at ... approximately 200m altitude and at about 80 knots airspeed. As a follow-up to ... the 1989 survey, and because dead gray whales were seen there in 1989, Tugidak .. and Sitkinak Islands were surveyed by helicopter during 14-16 July 1990 and from 28 August to 6 September 1990. lit Once a stnmded cetacean was located, and was in an acceptable condition (not putrefied) for necropsy and tissue collection, a crew was flown by helicopter to the -• stnmding site. Animals were considered inappropriate for necropsy if they had ... signs of being scavenged. showed visible signs of decomposition. or were known Ill to have been on the beach longer than 2 weeks. Where feasible, each whale was examined by a certified veterinary pathologist for gross evidence of oil-related or ... other causes of death. Multiple tissue samples were collected according to a ... prescribed standard protocol (Appendix I) developed for the EVOS and measure ... ments were obtained according to accepted cetacean necropsy procedures (Com IIi mittee on Marine Mammals 1961; Fay et al. 1979; Aguilar 1985). This project was funded only in 1989. ru1d tissue samples were collected only from carcasses .. exrunined then. Ill Tissue srunples were ru1alyzed for a broad spectrum of aliphatic and aromatic hydrocarbons hy the Geochemical and Envirorunental Research Group (GERG), ...- Texas A&M University. College Station, Texas. using capillary column gas chro ... matography with detection by flame ionization and mass spectrometry (GC/MS). .. Conclusions as to the presence or absence of petroleum in the sample were based on a preponderance of evidence such as the presence of the aromatic compounds ... naphthalene. dibenzothiophene. phenanthrene, tluorenes. and chrysenes as both