Tried to find the source of contamination beyond just contaminated shipping containers. I will post it if found.
FDA issues warning over possible radioactive shrimp
https://www.livescience.com/health/food-diet/fda-issues-warning-over-possible-radioactive-shrimp
Cs-137 contaminated shrimp? What we know
https://www.ans.org/news/2025-08-21/article-7299/no-small-matter-cs137-contaminating-shrimp/