Toxins in Coastal Waters: Will Surf Smelt and Other Forage Fish Survive?

Authors

Joy Cobb

Senior Project Advisor

Brady Olson

Document Type

Project

Publication Date

Winter 2025

Keywords

surf smelt, forage fish, diatoms, toxins, polyunsaturated aldehydes, oxylipins, Salish Sea, fish, embryonic fish, larval fish, ocean, phytoplankton, food web, fish life stages, marine ecology, fish ecology, coastal ecosystem, morphology

Abstract

Surf smelt are a forage fish—small fish that are prey for larger fish—native to the Salish Sea. They are a source of food for fish such as salmon and tuna and they act as important indicators of ecosystem health. Surf smelt spend their early life stages in shallow coastal waters where diatoms are also abundant. Diatoms are single-celled algae that release toxins called polyunsaturated aldehydes (PUAs) when they are broken down. The goal of this study was to test the effects of PUAs on the growth and development of surf smelt to determine possible causes of any future fluctuations in surf smelt populations. First, we took fertilized surf smelt eggs and divided them into two control groups and five treatment groups of increasing PUA concentrations. Then, we measured the mortality rate of embryos, as well as the body length and eye area of larval surf smelt post-hatch. We found that surf smelt embryos had greater mortality rates when exposed to high concentrations of PUAs, and larvae had reduced body length and eye size. These overall findings indicate that the early life stages of surf smelt are negatively affected by PUAs, suggesting that other forage fish, which are akin to surf smelt, will likely experience similar effects. Increased PUA concentrations in coastal waters will likely decrease forage fish populations and cause detrimental cascading effects throughout the Salish Sea food webs.

Department

Marine and Coastal Science

Recommended Citation

Cobb, Joy, "Toxins in Coastal Waters: Will Surf Smelt and Other Forage Fish Survive?" (2025). WWU Honors College Senior Projects. 915.
https://cedar.wwu.edu/wwu_honors/915

Type

Text

Rights

Copying of this document in whole or in part is allowable only for scholarly purposes. It is understood, however, that any copying or publication of this document for commercial purposes, or for financial gain, shall not be allowed without the author’s written permission.

Language

English

Format

application/pdf