International conservation and sustainability targets recommend increasing the marine area under protection and effective management to protect biodiversity and promote sustainable fisheries. Recently, national governments have gone big, creating very large marine protected areas, and questions have been raised about the effectiveness of management at such scale, the top-down approach and the low percentage closed to fishing. A bottom-up approach can result in socially-acceptable marine reserves, but scaling problems are common. From 15 years of experience in Mexico, we examine the biophysical monitoring costs of 25 no-take marine reserves, covering 186 km2, through a fisher-led citizen science program. Biophysical monitoring is important and remains the most effective method of scientifically documenting recovery. In our study, the average annual monitoring period costs USD$13,200 (including NGO participation), but would cost only USD$8,000 if fishers were able to operate independently. At present, fishers only cover 16% of the annual monitoring budget, with the majority covered by philanthropy. Data obtained by Causa Natura through FOI acts help us contrast the total amounts required to effectively maintain the marine reserves versus the distribution of financial resources in CONAPESCA´s (Mexico’s fisheries agency) subsidies program. For example, CONAPESCA subsidises fisheries to the tune of USD$123 million per year, but only 1.43% of the total amount between 2013-2018 (USD$9.6 million) has been assigned to the marine reserves under the agencies jurisdiction. Of this, 73.7% goes to only one of said areas, the Golfo de Ulloa, which is not no take. Options for increasing co-investment from the fishers and diversifying funding to assure the long-term viability of the reserves are discussed.