I haven't posted for a while on fishery issues. Such concerns occupied a fair amount of my research time in the early 1980s. This article in The Economist makes the case for imposing individual transferable quotas on ocean fish stocks. 121 of the ocean's fisheries operated under ITQ's are much healthier than those not managed in this way. The specific studies are referenced here.
Ocean fisheries outside national waters are notoriously difficult to police and groups such as the Japanese cheat in dramatic, stupid and self-defeating ways on assigned quotas. But apparently 90% of fish caught are caught in national waters so that these issues of cheating can be overstated. It is, however, true that most of Australia's ocean fisheries are heavily over-exploited. Indeed ocean fisheries generally are expected to collapse by mid-century at current rates of exploitation. This is a crisis situation. Although still reversible the loss of marine biodiversity is one of the major factors reeducing the productivity of the oceans.
I always enjoy showing to students that overexploitation reduces fish yields and increases fish harvest costs. The Japanese are shooting themselves in the foot by cheating on international conservational agreements for such species as Southern bluefin tuna.