“Overfishing and overcapacity are costing the world’s fishery sector dearly, reducing resource rent—the surplus after fishing costs have been subtracted from revenue—by
selleckchem an estimated US$50 billion a year according to two recent studies based on different methodologies  and . Meanwhile, the gap between global revenue and costs narrows , with global revenue from marine fisheries at approximately US$95 billion , ,  and  and the total variable cost of fishing estimated at US$92 billion (both in real 2005 dollars) . Excess subsidies, by one estimate topping US$27 billion per year currently , largely fuel this cycle of dysfunction. Against this backdrop, the human consumption of fish has been rising, up 9% from 2002 to 2006 alone . To support this, overall fish production from both capture fisheries and aquaculture continues to climb, reaching a level in 2006 more than seven times that recorded for 1950 . The phenomenal growth of aquaculture is responsible
for the recent growth, selleck monoclonal antibody and nearly half of the world’s food fish supply is farmed at present . But just as the overall rise in fish production hides the stagnation in catches from the world’s capture fisheries over the past two decades  and , global catch trends mask successive declines in regional stocks  and the geographic spread of overfishing in time  and . Indeed, the roughly fivefold increase in marine fishery catches from 1950 to the late 1980s when catches peaked was facilitated by the expansion into and exploitation Branched chain aminotransferase of new fishing areas, from the North Atlantic and Western Pacific coastlines southward and into the high seas . Defining thresholds of unsustainable fishing across the diverse marine ecosystems and fisheries of the world is an uncertain task and a matter of lively debate (e.g.,  and ). In the absence of scientific stock assessments for all commercial species, studies have evaluated overfishing at a global scale by extrapolating
from available stock assessments and research surveys ,  and ; using catch trends as an indicator of stock biomass levels ; combining catch data with primary productivity levels  and  or empirical stock-assessment based relationships ; or some combination of these methods . Despite ongoing controversy regarding the interpretation of data sources, consensus is emerging; according to several recent assessments, up to one-third of global fishery stocks are now overexploited or collapsed , , , ,  and . These assessments document the geographic spread and intensification of overfishing from the 1950s to the 1990s, with the proportion of depleted stocks stable since the 1990s in some analyses  and  and increasing at different rates in others ,  and .