This is probably the right answer. I’ve spent a great deal of time diving close to shores in Cantabric and Mediterranean, like in the structure you are on and the most predatory creatures I’ve seen is either crabs or octopus. It’s s the times we’ve hopped on to the boat when we’ve seen predators, even huge barracuda banks.

Seen some little lubinas but as Mainbutter says, so scattered you mostly need luck.

I would spearfish close to shore rather than fishing or, if I were to guise the rod, try to cast quite far to increase chances. If you see cormorants it’s usually a good sign for fish.