The oceans are facing collapse due to overfishing. According to the U.N.'s State of World Fisheries and Aquaculture (SOFIA 2010), 85 percent of the world's fisheries are now either overexploited, fully exploited, significantly depleted or recovering from overexploitation. No matter which category is considered, there is no good news.
A study published in the scientific journal “Nature” in 2003 concluded that 90 percent of the "big" fish -- tuna, swordfish and marlin -- are already gone. In a 2006 study, leading scientists found that 29 percent of all global commercial fisheries have collapsed due to overfishing, pollution or habitat loss.
You can learn more in Oceana's report, Too Few Fish: A Regional Assessment of the World’s Fisheries.