Population surveys of the Devils Hole pupfish began in 1972. Population counts since then have been conducted using the same methods, with scuba diving researchers counting fish starting at depths of while researchers above the water count the individuals on the shallow shelf. From 1970 through 1996, the average population was 324. Population highs were recorded in 1980, 1990, and 1995 at counts of 541–548 individuals. Since 2005, the population at Devils Hole has been below 200 individuals, although the population fluctuates depending on the season. Low algae growth and other winter conditions cause spring populations to be 35–65% of the autumn population. The reasons for the decline of the population are unclear. A 2014 study ascertained that the Devils Hole pupfish had a 26–33% chance of becoming extinct in the next twenty years  In November 2005, divers counted just 84 individuals in the Devils Hole population, the same as the spring population, despite observations of egg-laying and juvenile fish during the summer. In 2007, between 38 and 42 fish were left in Devils Hole. The pupfish count rose in the autumn of 2008 to 126, the first steady increase in more than 10 years. As of April 2013 U.S. Fish and Wildlife reported only 35 fish remain in their natural habitat, but increased to 92 when measured again in 2014. As of spring 2016, a periodic count found 115 of the fish living in the waters. In spring 2019, the pupfish population reached 136, the highest springtime population since 2003. Many of the various surviving local "Cyprinodon" species and subspecies (pupfish), including the Devils Hole pupfish, are on the IUCN Red List of threatened species: