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Map of Prince William Sound, Alaska with the streams and hatcheries assessed for straying identified.
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... linear relationship between the proportion of hatchery strays and geographic distance from a hatchery. We assumed this relationship would apply to other streams in southwest Prince William Sound, and used nautical charts to estimate dis- tances through the marine environment from hatcheries to other streams assessed for impacts from the oil spill (Fig. 1 where Y is the proportion of hatchery fish in a stream, and X is the distance in nautical miles of a stream to the closest hatchery. For each stream, we added the estimated proportion of strays from each hatchery to obtain a total proportion of hatchery ...
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In recent years, the shipping of environmentally hazardous cargo has increased considerably in the Baltic proper. In this study, a large number of hypothetical oil spills with an idealized, passive tracer are simulated. From the tracer distributions, statistical measures are calculated to optimize the quantity of tracer from a spill that would stay...
Citations
... After 1990, when oil had essentially left the streams, the egg mortality was hypothesized to have been caused by intergenerational genetic damage or physiological anomalies passed on to the progeny (Craig et al., 2002;Rice et al., 2001). However, hatchery strays make up a significant proportion of the spawning populations of PWS streams (Collins, 2002;Evans, 1999, 2000), and can account for over 80% of the total spawners in streams closest to the hatcheries (Collins et al., 2009a;Cronin and Maki, 2004). Hatchery fish experience only oil-free freshwater incubation conditions and thus would carry no genetic or physiological aberrations from oil toxicity to pass on to their progeny. ...
... The egg viability of adults returning from fry releases in 1998 were unaffected from exposure as embryos to two different oil concentrations experienced under laboratory conditions that were higher than what was experienced by embryos in PWS streams in 1989 and 1990. Consequently, the absence of reproductive effects at the Heintz (2002) TPAH levels tested imply there would be little risk to the productivity of pink salmon that were incubated in oiled steams, and is consistent with other data showing there were no inter-generational impacts due to oil-exposure Brannon and Maki, 1996;Cronin and Bickham, 1998;Cronin et al., 2002;Cronin and Maki, 2004). ...
The Exxon Valdez oil spill that occurred in Prince William Sound, Alaska, in March of 1989 was the largest crude oil spill in the United States at that time, and it was anticipated to have disastrous effects on the ecology and fisheries of that coastal region. The large pink salmon returns to the sound, a major commercial species in Alaska, were of great concern. The Exxon Valdez Oil Spill Trustee Council, a council of government agencies formed to assess the impact of the spill for recovery purposes, concluded that pink salmon in Prince William Sound were damaged by the oil, based on investigations of the Alaska Department of Fish and Game and the National Marine Fisheries Service. Agency scientists claimed that the oil increased incubation mortality of pink salmon and those exposed to oil experienced less growth, higher long-term mortality, and reduced reproductive success. This contrasted with data and conclusions of the non-agency scientists led by the University of Idaho researchers that showed no impact of oil on incubating eggs or on juvenile pink salmon in marine waters, and no reduction in egg viability of returning adults. In this article the authors re-examine the evidence and resolve the problems that resulted in the different interpretation of research conducted by agency and non-agency scientists. The resolution has far reaching implications on ascertaining the impacts of marine oil spills.
Alaskan salmon are of major sport and commercial importance, figure importantly in the traditions and livelihood of native cultures, and support food webs for an array of carnivores and scavengers. Of the five Pacific salmon species, pink salmon (Oncorhynchus gorbuscha) are the most abundant in Prince William Sound (PWS). Annual harvests yield 20-70 million adult pink salmon, with a value that averaged over $29 million annually between 2001 and 2010 (Fig. 12.1). The subsistence and commercial importance of the pink-salmon fishery, combined with the overlap of the 1989 Exxon Valdez oil spill with the early life stages of the salmon, make understanding the effects of the spill both critical and challenging. Following the spill, the commercial pink-salmon fishery was closed. In addition, an Oil Spill Health Task Force was organized to ensure the safety of subsistence foods. The Task Force used analytical data on hydrocarbons in pink salmon (and other subsistence foods) (Field et al., 1999) and determined that there were no Exxon Valdez polycyclic aromatic hydrocarbons (PAH) in sampled edible salmon tissues in 1989 and 1990.
Breeding programs may have the unintended consequence of elevating levels of inbreeding; mutations unmasked through inbreeding may have deleterious effects on salmonid population viability. We used induced all-paternal inheritance (androgenesis) to assess the incidence of mutations affecting early development in rainbow trout (Oncorhynchus mykiss) and to provide insights into the genetic basis for inbreeding depression. Assays conducted on androgenetic haploid embryos derived from four rainbow trout populations allowed us to test whether a homozygous clonal line produced in our laboratory had been purged of deleterious alleles affecting early embryonic development. Assays showed no significant difference in viability of androgenetic haploids produced from clonal or outbred lines of rainbow trout during early development. These results are not consistent with the dominance hypothesis of inbreeding depression, which attributes inbreeding depression primarily to expression of deleterious recessive alleles. However, significant maternal effects on haploid embryo viability were identified, implying that egg quality may have a larger effect than paternally inherited deleterious recessive alleles on early haploid embryonic development. Androgenetic haploid assays may thus be useful as a stringent measure of egg quality in aquaculture breeding programs.
For sixteen years following the 1989 Exxon Valdez oil spill adult returns of pink salmon in Prince William Sound, Alaska were monitored to assess spill effects on survival. No evidence of spill effects was detected for either intertidal or whole-stream spawning fish. From 1989 through 2004 mean densities for oiled and reference streams tracked each other, illustrating similar responses of oiled and reference stream adult populations to naturally changing oceanographic and climactic conditions. Hatchery fish strayed into the study streams, but similar incursions occurred in oiled and reference streams, and their presence was compensated for to eliminate their influence on determining the success of the returning natural populations. These results, showing no detectable effects of oiling on pink salmon spawning populations, are supported by published field studies on pink salmon incubation success in oiled streams.
