Could Tuna Become as Expensive as Caviar?

Do you enjoy a tuna sandwich? If things don’t change, you might find that this simple sandwich becomes much pricier and less available in the coming years.

As ocean temperatures rise, many fish species, including tuna, are expected to shrink significantly. Scientists predict these fish could be 30% smaller than they are now.

The reason is that as ocean waters heat up, fish aren't able to absorb enough oxygen to grow properly. Fish are cold-blooded animals and cannot regulate their body temperature. When ocean water becomes warmer, a fish's metabolism speeds up, requiring more oxygen for bodily functions. The problem? Warm water contains less oxygen than cold water. Without enough oxygen, fish simply can't reach their full growth potential.

Why is tuna particularly at risk? Tuna are fast-moving fish and consume more oxygen than an average fish, researchers say, so warming waters are likely to significantly affect their size.

Researchers conducting the study on ocean warming’s impact on fish size highlight that we are already witnessing smaller fish due to decades of warming: "Researchers in the UK examining decades of data on North Sea fish found species like sole and haddock have already shrunk in size—and the most significant changes are in areas where the water has warmed the most."

If that wasn't enough, researchers note the most severe outcome of insufficient oxygen is not just smaller fish, but fish suffocating to death, although this only occurs in cases of external oxygen shortages.

Smaller fish will not only lead to higher prices in the fish market and economic challenges for fishermen but also pose issues for larger fish, which rely on smaller fish as a food source. Warming ocean waters that make tuna less available for you will also diminish the food supply for larger fish.