Thanks to social media, canned sardines are a scarcity on the supermarket shelf. Supermarkets across the country are facing a noticeable shortage of the popular staple. The missing tins are the result of a sudden spike in popularity colliding with severe environmental problems out at sea.

For generations, canned sardines were seen as a cheap, humble pantry item. That changed recently as social media trends and a growing interest in high-protein, healthy foods turned tinned seafood into a viral food craze. One top trend touts a sardine-only diet lasting one to three days, promoted by figures like Dr. Annette Bosworth and Dr. Mindy Pelz.

But ocean conditions have made it nearly impossible for suppliers to keep up. Warming waters disrupt plankton, forcing sardines into deeper waters. The problem is especially severe in Morocco, which supplies much of North America and Europe. Fishermen report catches down by more than half.

Wildlife officials in the United States and other countries have enforced strict fishing limits to protect stocks. Industry experts say the empty shelves may remain for a while because rebuilding sardine numbers will take time.