Changes in length and mass of rock scallops (<i>Spondylus calcifer</i>) and black murex snails (<i>Hexaplex nigritus</i>) before and after reserve establishment.

<p>(a) Comparison of the average adductor muscle length and mass of rock scallops from fishing areas (2002 = Spring, two months before reserve establishment). Data from reserves was not obtained as animals would have needed to be sacrificed. (b) Comparison of the average live mass of black murex snails from reserve and fishing areas.</p

Rules and levels of compliance before and after entrance of roving bandits^†.

†<p>Compliance levels based on percentage of fishers known to have broken the rule at least once: 1 = very low (<10%), 2 = low (10–40%), 3 = moderate (41–60%), 4 = high (61–90%), 5 = very high (>90%). Time A = June 2001–May 2004, Time B = first six months (June–November 2004) after entrance of roving bandits.</p

Rapid rise and fall of San Jorge Island fishery stocks from summer 2002, when the Puerto Peñasco community-based reserve network was established, to the end of summer 2004, three months after roving bandits poached on the island.

<p>The graph depicts differences in relative densities (S.E. bars included) from one monitoring season to another for the main species harvested: murex snails (<i>Hexaplex nigritus</i>) and rock scallops (<i>Spondylus calcifer</i>).</p

Community-based marine reserve network of Puerto Peñasco and sequential phases of poaching.

<p>During the first phase (green), divers from other locations, “roving bandits”, poached on the San Jorge Island reserve. This was followed by local rule breaking and some divers from Puerto Peñasco poaching on the Island (second phase, pink arrows). During the third phase (yellow), all members of the Puerto Peñasco diving cooperative broke their local rules and coastal reserves were targeted. It took less than two months for rules to be broken by all local divers after entrance of roving bandits.</p

Formal and informal sanctions by rule type devised by local fishers.

<p>Formal and informal sanctions by rule type devised by local fishers.</p