It's unfortunate that more people don't internalize this fact. One of the first things you learn in middle/high school ecology is that 90% of available energy is lost between each step in the food chain. Producers can only convert about 10% of the sun's energy to useful electrons in photosynthesis, herbivores only get 10% of the energy it takes to grow their food, and carnivores only get 10% of the energy herbivores take in. Some factors like the decreased non-predatory death improve those numbers for industrial agriculture but not by much.

In US agriculture, we have some estimates for the ratio of output calories to the input calories [1] that are astounding. For every 100 kcal of feed stock, we get ~19 kcal back from chicken, ~7 kcal from beef, and a whopping 1 kcal from shrimp.

Essentially, every 1000 kcal of beef takes 14,000 kcal of corn/soy/alfa-alfa and 1000 kcal of shrimp takes 100,000 kcal of whatever it is shrimp eat.

[1] From the book Diet, Energy, and Global Warming by Eshel and Martin