The male sperm is very sensitive and can lose viability due to external factors such as getting over heated.
That said, my "end hunger" case doesn't hang on the viability of GM crops.
Seed buried in a peat soil for 20 years retained 8% viability.
As an integrated subsystem to any OTEC facility cold sea water air conditioning significantly increases the economic viability of development.
Animals vary very greatly in viability (see Longevity), and practical experience has shown that certain species bear captivity well, whilst others for reasons that appear to be psychological as well as physical quickly succumb.