Effect of Commercially Available Egg Cures on the Survival of Juvenile Salmonids

Shaun Clements,Rob Chitwood,Carl B Schreck

doi:10.1371/journal.pone.0021406

Abstract

There is some concern that incidental consumption of eggs cured with commercially available cures for the purpose of sport fishing causes mortality in juvenile salmon. We evaluated this by feeding juvenile spring Chinook (Oncorhynchus tshawytscha) and steelhead (O. mykiss) with eggs cured with one of five commercially available cures. We observed significant levels of mortality in both pre-smolts and smolts. Depending on the experiment, 2, 3, or 4 of the cures were associated with mortality. Mortality tended to be higher in the smolts than in the parr, but there was no clear species effect. The majority of mortality occurred within the first 10 d of feeding. Removal of sodium sulfite from the cure significantly reduced the level of mortality. Soaking the eggs prior to feeding did not reduce mortality. We observed a clear relationship between the amount of cured egg consumed each day and the survival time. We conclude that consumption of eggs cured with sodium sulfite has the potential to cause mortality in juvenile steelhead and Chinook salmon in the wild.

Highlights

Anglers in the Pacific Northwest and the Midwest states of the U.S often use eggs that are cured with a mix of preservatives, dyes, salts, and sugars as bait for trout and salmon
Our objective was to determine whether ingestion of eggs cured with commercially available cures affected the survival of juvenile salmonids
We showed that consumption of eggs cured with some commercially available cures cause mortality in juvenile salmonids

Summary

Introduction

Anglers in the Pacific Northwest and the Midwest states of the U.S often use eggs that are cured with a mix of preservatives, dyes, salts, and sugars as bait for trout and salmon. These eggs may either be purchased pre-cured or anglers can purchase the cures or cure ingredients and prepare their own eggs. The level of exposure experienced by individual juvenile fish is unknown, but in areas of heavy fishing pressure it is potentially quite high Factors such as the number of anglers fishing cured eggs, the time spent fishing in the home range or vicinity of an individual fish, the appetite of the fish, and the density of fish in an area could all affect the level of exposure

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