Discussion

What did the results tell us?

Retene did not significantly affect survival or growth in any concentration; however, all wood leachates were toxic to herring larvae. Larval mortality was 100% in the highest concentration (100%) and after only two days of exposure. Cedar chips and fir chips significantly decreased survival in the 50% concentration.

Where do we go from here?

Our study showed that fresh wood chips can reduce survival and dry biomass of Pacific herring larvae; however, we used wood that was recently chipped from the lumber mill. Does the aged wood debris that contaminates Puget Sound embayments still contain harmful substances that can leach into Sound waters and sediments? How much wood debris should be removed from the Puget Sound? Experiments assessing how toxic wood laying in Puget Sound and the sediment associated with it are to herring embryos.

Why is this important?

Pacific herring were once commercially important as a source for roe and bait fishing and herring still are important to marine mammals, fish, and birds. Pacific herring have higher lipid content than pollock (Theragra chalcogramma). It is hypothesized that the decline of stellar sea lions off the coast of Alaska is a result of diet switching from herring to pollock (Kumagai et al. 2004). Diet shifts in marine animals dependent on herring might be similar to that seen in the declining stellar sea lion population. It is important to understand what affects survival and growth of herring so they can be protected.

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References

Kumagai, S., Rosen, D. and Trites, A. 2004. Body mass and composition responses to short-term low energy intake are seasonally dependent in Steller sea lions (Eumetopias jubatus). Journal of Comparative Physiology B. 176:589-598.
Page Updated 06.12.2012