Okay, so imagine you're swimming in the ocean and you see a lot of small fishes swimming together in a big group. That's called a shoal of herring. Just like how you and your friends like to hang out and do things together, herring like to stick together for safety and to find food.
Sometimes, when a shoal of herring gets really big, it can look like a giant moving blob in the water! It's pretty neat to see. But predators like birds and bigger fish also like to eat herring, so the shoal has to stay together and move quickly to avoid getting caught.
Humans also like to catch herring for food, so sometimes we send boats out to catch them. But we have to be careful not to take too many herring or else the whole shoal could be in danger.
Overall, the shoals of herring are a really interesting and important part of the ocean's ecosystem, and we need to protect them to keep everything in balance.