Eric Pineda, a dock agent in the old Chilean port of Talcahuano 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.

“It’s going fast, he said as he looked at the 57-foot boat. “We’ve got to fish harder before it’s all gone. Asked what he would leave his son, he shrugged: “He’ll have to find something else.

Jack mackerel, rich in oily protein, is manna to a hungry planet, a staple in Africa. Elsewhere, people eat it unaware; much of it is reduced to feed for aquaculture and pigs. It can take more than five kilograms, more than 11 pounds, of jack mackerel to raise a single kilogram of farmed salmon.

Stocks have dropped from an estimated 30 million metric tons to less than a tenth of that in two decades. The world’s largest trawlers, after depleting other oceans, now head south toward the edge of Antarctica to compete for what is left.

An eight-country investigation of the fishing industry in the southern Pacific by the International Consortium of Investigative Journalists shows how the fate of the jack mackerel may foretell the progressive collapse of fish stocks in all oceans.

In turn, the fate of this one fish reflects a bigger picture: decades of unchecked global fishing pushed by geopolitical rivalry, greed, corruption, mismanagement and public indifference. Daniel Pauly, an eminent University of British Columbia oceanographer, sees jack mackerel in the southern Pacific as an alarming indicator.

“This is the last of the buffaloes, he said. “When they’re gone, everything will be gone.

Delegates from at least 20 countries will gather Monday in Santiago for an annual meeting to seek ways to curb the plunder.

The South Pacific Regional Fisheries Management Organization was formed in 2006, at the initiative of Australia and New Zealand along with Chile. Its purpose was to protect fish, particularly jack mackerel. But it took almost four years for 14 countries to adopt 45 interim articles aimed at doing that. Only six countries have ratified the agreement.

Meanwhile, industrial fleets bound only by voluntary restraints compete in what amounts to a free-for-all in no man’s water at the bottom of the world. From 2006 through 2011, scientists estimate, jack mackerel stocks declined 63 percent.

The fisheries convention needs eight signatures to be binding, including one South American coastal state. Chile prominent in getting the group together has yet to ratify.

The South Pacific fisheries organization decided at the outset that it would assign future yearly quotas for member countries based on the total annual tonnage of vessels each deployed from 2007 to 2009.

To stake claims, fleets hurried south. Chinese trawlers arrived en masse, among others from Asia, Europe and Latin America.

2012 The New York Times Company