Introduction

Why use a Pacific herring bioassay?

Pacific herring are an important forage fish for many marine species and humans also use them as bait and food. The large number of species dependent on the herring makes them an important food web species (Lassuy 1989). The population of Pacific herring at Cherry Point, Washington once produced the highest spawning biomass in Puget Sound, which currently exists at about 10% of its historical spawning biomass, has shown no increase since fishing was stopped in 1985 (Figure 1). Herring embryos are sensitive to low concentrations (~1ppb) of polycyclic aromatic hydrocarbons (PAHs) found in crude oil (Carls et al. 1999). Herring being an important food web species and the sensitivity herring show to crude oil, makes herring a valuable bioassay.

Figure 1: From North Cascades Audubon Society

Why use wood leachates?

In Port Gamble, Washington, a sawmill operated for 142 years before closing in 1995, leaving tons of wood debris in the bay. This accumulated wood and bark from multiple tree species could be harmful to herring. Prior research has shown that toxicants including PAHs can leach from wood into the water (Barney and Colt 1991). Port Gamble is a spawning site for Pacific herring that has been observed to have egg mortalities of greater than 20%. This is high compared to most other herring spawning sites in Puget Sound (Kurt Stick, WDFW, pers. comm.).

Purpose

The purpose of our project was to determine if wood leachates affect survival and growth of Pacific herring larvae. This study measured the toxicity of retene (a PAH component of wood leachate) and four wood leachates to Pacific herring larvae (fir bark, hemlock chips, cedar chips and fir chips) and at five concentration of each leachate (100%, 50%, 25%, 12.5%, 6.25 % and a control). We hypothesized that purified retene and wood leachates would affect survival and growth. Results of our experiments may inform decisions about cleanup efforts in Port Gamble (and other wood-contaminated sites) and provide data on the effects of wood-derived substances on an important local fish species.


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References

Carls, M., Rice, S. and Hose, J. 1999. Sensitivity of fish embryos to weather crude oil: Part I. Low level exposure during incubation causes malformations, genetic damage, and mortality in the Pacific herring (Clupea pallasi). Environmental Toxicology and Chemistry 18:481- 493.

Lassuy, D.R. 1989. Species profiles: life histories and environmental requirements of coastal fishes and invertebrates (Pacific Northwest)—Pacific herring. U.S. Fish Wildlife Service Biol. Rep. 82(11.126). U.S. Army Corps of Engineers, TR-EL-82-4. 18 pp.
Page Updated 06.12.2012