That's the sexy part

I had a thieving boss like you one time. After a while I started to make sure after any meeting that everyone would get back the pens he had managed to get his grubby little mittens on.

Why? It's not like there are suddenly no humans at sea. Small fishing vessels may have gone down in number but in the meantime leisure vessels and the sheer number of humans have gone up (it's massive). Humans are ⅓ of all land mammal biomass. Whale scientists are probably more puzzled by the lack of species diversity among land mammals that visit the sea.