Unfortunately mining is often more lucrative than tourism, especially in remote areas like Bangka which attract mere handfuls of divers and few others.
"The majority of the inhabitants are Malay Indonesians and Chinese mostly Hakkas. The population is split between those who work the pepper farms and those who
work on the tin mines."
Unless the mining operation interferes with the pepper farms, I don't think anyone there gives a damn. You really want to make a difference with a petition, get the pepper farmers to sign, and get some lobbying support from the pepper industry. No one is going to care about a petition signed by foreigners who like to see fish any more than they'd care about a petition signed by fish.