El Niño events influence physical characteristics in the Eastern Tropical Pacific and lead to a decrease in nutrient and phytoplankton concentrations and to variation in the composition of the marine trophic chain. El Niño events can also provide an evaluation of the effect climate change may have on marine ecosystems. The Galapagos coastal fin-fish fishery is conducted by approximately 400 fishers that target species that include benthic/demersal predatory fish such as the endemic Galapagos whitespotted sandbass (Paralabrax albomaculatus), the regional endemic sailfin grouper (Mycteroperca olfax) and mottled scorpion fish (Pontinus clemensi), and the misty grouper (Hyporthodon mystacinus). The first two species are listed as vulnerable and endangered, respectively, on the IUCN red list of threatened species. Despite their potential to affect, at present it is unclear how El Niño events influence artisanal fin-fish fisheries in the Galapagos. To study the impacts of El Niños on the fishery, catch composition at the largest dock in Santa Cruz Island was recorded during March and April 2013, 2014 and 2016 and compared.
Compositions were significantly different among the three years but differences were largest when compared to 2016 due to the increase in size of species commonly caught and appearance of uncommon demersal/benthic predatory fish such as Grape eye seabass (Hemilutjanus macrophthalmos) and Pacific dog snapper (Lutjanus novemfasciatus). We hypothesize that changes in catch composition were a product of a reduction in primary production that led to an increase in water clarity and decrease in prey biomass that forced these benthic fish species to change their feeding behavior and strike at baits that usually would not be easily located. Because of the conservative life history many of these benthic predatory fish exhibit, the El Niño events may have profound effects on their populations due to the elimination of the largest individuals. Therefore, management actions directed at reducing the impact of the fishery on these important fish populations in the near- (El Niños) and long-term (climate change) future should be encouraged.