An Assessment of Oil-Spill Effects on Pink Salmon Populations Following the Exxon Valdez Oil Spill—Part 1: Early Life History

Abstract

Pink salmon, Oncorhynchus gorbuscha, is the main salmon species of commercial importance in Prince William Sound. Unlike other Pacific salmon, they have a two-year life cycle and have adapted to spawn in the intertidal reaches of numerous small streams throughout the oil-spill area. Thus, they represent the species at highest potential risk for spill-related injury. This paper discusses results of field programs initiated within a few days of the spill and designed to assess spill effects on critical early life stages of pink salmon in postspill years. Samples of water and stream sediments from throughout the spill area were used to define the exposure of pink salmon to residual hydrocarbons from the spill. Mean sediment concentrations of polycyclic aromatic hydrocarbons (PAH) up to 300 ppb were measured in oiled streams in 1989 and generally followed a downward trend toward background in 1990 and 1991. These PAH concentrations were then used in regression analyses of potential effects on key early life stages of pink salmon. Water samples taken from both nearshore feeding and rearing areas and offshore migratory areas show that hydrocarbon concentrations were from one to four orders of magnitude lower than concentrations reported in the literature to cause acute or chronic effects on fish species. The postspill field and laboratory studies of pink salmon early life stages included examination of potential effects on 1989, 1990, and 1991 eggs, fry, and juveniles. Generally high survival, ranging from 77% to 100%, was observed in both oiled and reference streams in 1989, and a weak correlation was indicated with stream sediment PAH at only one of the three tide levels sampled (12 feet). In 1990, egg viability was 90.6% from reference streams and 91.1% from oiled streams, as determined through incubation studies. Mean condition index, kD, was 1.76 for fry from reference streams and 1.79 from oiled streams, indicating normal developmental timing. Study results show that no substantial effects on critical early life stages of pink salmon in Prince William Sound are attributable to the spill. Results of incubation experiments with eggs from the spill-affected area provide no indication of sterility or abnormal development. Our results are consistent with the pink salmon returns in 1990 and 1991 that yielded returns over three times the size of the parental year class.

Mechanism for transport of oil-contaminated groundwater into pink salmon redds

“…The study was completed in June 2000 at 2 pink salmon streams in western PWS, Sleepy Creek on (Gundlach et al 1990) and studied by Brannon et al (1995), Bue et al (1996Bue et al ( , 1998, Craig et al (1999), and Murphy et al (1999). Evidence of oil persisted in beaches around both streams through at least 1995 (Murphy et al 1999), and pink salmon egg survival was monitored through 1997 (Bue et al 1998, Craig et al 1999.…”

“…Because flowing freshwater diverted oil from streams, Brannon et al (1995) and Brannon & Maki (1996) argued that the oil concentrations in stream sediment were too low to damage pink salmon. These researchers reported that mean total polycyclic aromatic hydrocarbon (PAH) concentrations in the sediment of oiled streams were low, 0.5 to 2818 ng g -1 (but greater than in non-oiled reference streams, 0.2 to 64 ng g non et al (1995) failed to detect oil-related embryo mortality, but data were limited to a single year and included fewer eggs and less stream area than observed by Bue et al (1996Bue et al ( , 1998 and Craig et al (1999).…”

Estimation of polycyclic aromatic hydrocarbon concentrations in the water column based on tissue residues in mussels and salmon: An equilibrium partitioning approach

“…Chem. 15,1996 2241 lyzed for individual and total PAHs by the National Oceanic and Atmospheric Administration (NOAA) [3,8,16,17], the Alaska Department of Fish and Game (ADFG) [18], the University of Alaska [19], and contract research organizations (Battelle Ocean Sciences; Arthur D. Little, Inc.; America North EMCON; Kinnetic Laboratories; Dames and Moore) hired by Exxon following the Exxon Valdez oil spill [5,9,10]. The PAH analyses of the state, federal, and university samples were reported in the U.S. government database PWSOIL [20].…”

“…Young pink salmon, Oncorhynchus gorbuscha, were collected from April through June 1989 from the top few meters of the water column in the western sound [8]. Pink salmon alevins (preemergent salmon still living in gravel) were collected from streambed gravels in oiled and unoiled areas of the sound during 1989-1991 [10,18].…”

“…Some fish, mussels, and other marine animals living in the spill path bioaccumulated petroleum hydrocarbons, including polycyclic aromatic hydrocarbons (PAHs) derived from the spilled oil [6][7][8][9][10]. The PAHs probably were derived primarily from bioaccumulation of PAHs from the spilled oil that was dissolved or dispersed in the water column.…”