We used something like these when I was a kid. In the village where I grew up someone had made a concrete barrier about ~70cm high between some rocks (see [0],

We used something like these when I was a kid. In the village where I grew up someone had made a concrete barrier about ~70cm high between some rocks (see [0], it's now a bit ruined) that created a rockpool as the tide went out. Fish (usually little shoals of young mackerel we called "sile") would collect there and it was pretty easy and fun to catch them with a net. Oh and there was a small pipe in the barrier that drained the water so if you were really lazy you could just sit there with a net and grab them as it drained. [0] = https://www.google.com/maps/@56.793725,-2.3355133,3a,28.8y,58.39h,70.45t/data=!3m8!1e1!3m6!1sAF1QipPW1bNKtqtUr9WCqoIjnThNrWwFkaqhS96b-ZHu!2e10!3e11!6shttps:%2F%2Flh5.googleusercontent.com%2Fp%2FAF1QipPW1bNKtqtUr9WCqoIjnThNrWwFkaqhS96b-ZHu%3Dw203-h100-k-no-pi-0-ya51.274452-ro-0-fo100!7i6080!8i3040 https://www.google.com/maps/@56.793725,-2.3355133,3a,28.8y,5...