Fisherman Luis Enrique Bonilla just wants to make a living. Galapagos Islands conservationists, worried that the marine reserve is overfished, want him to work in tourism.

Bonilla and the local fishermen he represents say a move from commercial fishing to boat tours is an expensive and complex prospect for which they have no money or training. They’ve already made concessions to preserve marine species: each owning only one small boat and using simple lines and lures to catch fish by hand.

But even with the restrictions, some species in the Galapagos Marine Reserve have been decimated — including sea cucumbers and lobster — putting even more pressure on fishermen forced to live off smaller catches.

On the eve of Charles Darwin’s 200th birthday, Bonilla’s story shows just how hard it is to protect the archipelago’s biodiversity that Darwin made famous. Changing livelihoods from those that destroy the islands to those that sustain them is easier said than done.

The marine reserve, home to more than 3,000 species, has suffered over the years from fishermen eager to exploit local, national and international markets, park officials say.

Edwin Naula, director of tourism and a former director of the Galapagos National Park, said it has been a struggle to get fishermen to comply with rules to protect the reserve. “It’s like when you have your children in the house and everything is out of order. And of course the children get angry when the father comes home and tells them to put things in order,” he said.

Darwin, who was born Feb. 12, 1809, first arrived nearly 175 years ago, discovering the unique species that would become the basis for his theory of evolution. The spectacular subjects of his work, including finches, giant tortoises, marine iguanas and blue-footed boobies, now draw more than 150,000 tourists a year to the Ecuadorean islands about 1,000 kilometres offshore in the Pacific Ocean.