单选题 .  When fisheries have sunk or collapsed, one approach to fix the situation is to set up a marine reserve where fishing is banned. The idea is to provide relief to stressed fish stocks by providing safe living environment where fish can reproduce, and then spread out.
    Jennifer Caselle, a biologist from University of California, provided a local example of success. In 2003, the state of California set up a network of 12 marine reserves near Los Angeles and banned fishing in more than 488 square kilometers. By monitoring the area before and after, Caselle and her colleagues found that over 5 years there were 50% more blue rockfish and other species targeted by fishing inside reserves than outside. There was no change in species that people don't eat, suggesting that fishing restrictions were responsible for the recovery.
    Another success story comes from Australia, which created the first large marine reserve in the Great Barrier Reef Marine Park in 1975. After a major die-off of coral (珊瑚), the government decided in 2003 to rezone the park and increased the proportion of no-take areas from less than 5% to 32%. Many fish species quickly doubled in sire and numbers. The new reserves also seemed to improve ecosystem health in general, as outbreaks of coral-eating starfish were nearly 4 times more frequent on the reefs where fishing was still permitted.
    What makes a marine reserve successful? Taking a broad look at 56 marine reserves around the world, Joshua Cinner of James Cook University examined the social and economic factors. The number of people living near the reserves played a big role in some cases. In the Caribbean, reserves near large populations tended to have less fish relative to unprotected areas than did reserves that were more remote. But the opposite was true In the Western Indian Ocean. It's not clear why, but one reason could be that people tend to move to places with healthy marine reserves so that they can fish nearby.
    Another factor related to successful marine reserves was, as expected, compliance (遵从) with fishing restrictions. And that tended to be associated not just with enforcement, but more complicated social dynamics such as how well people work together and participate In research and management. "In areas where people work together to invest in their resources, we saw less people illegally catching fish inside marine reserves," Cinner said in a statement. "To get high levels of compliance with reserve rules, managers need to foster the conditions that enable participation in reserve activities, rather than just focusing on patrols."1.  Fisheries sink or collapse when ______.