TALCAHUANO, Chile — Eric Pineda, a dock agent in this old port south of Santiago, peered deep into the Achernar’s hold at a measly 10 tons of jack mackerel — the catch after four days in waters once so rich they filled the 17-meter fishing boat in a few hours.

Mr. Pineda, like everyone here, grew up with the bony, bronze-hued fish they call jurel, which roams in schools in the southern Pacific.

(Reuters) - Representatives from around the world gather in Rio in June to try to hammer out goals for sustainable development at a U.N. conference designed to avoid being tripped up by the intractable issue of climate change.

But there is concern in the lead-up to the conference, known as Rio+20 or the Earth Summit, that it risks ending up as all talk and little action.