Brett Gardner #11of the New York Yankees dives into second base on the back end of an attempted double during the first inning in a MLB baseball game at Yankee Stadium on September 3, 2014 in the Bronx borough of New York City. Gardner was tagged out on the play. (Photo by Rich Schultz/Getty Images)

Tourists ice skate at night on the Eiffel Tower's skating rink in Paris December 9, 2014. The skating rink, located on the first level of the Eiffel Tower, opens to the public as part of the Christmas holiday season. (Photo by Charles Platiau/Reuters)

Indonesian mahouts clean their Sumatran elephant in a river near the zoo in Medan, North Sumatra, Indonesia, 12 December 2014. According media reports, the smallest of the Asian elephants, Sumatran elephant (Elephas maximus sumatrensis) is facing serious pressures arising from illegal logging and associated habitat loss and fragmentation in Indonesia. The population has come under increasing threat from rapid forest conversion to plantations. (Photo by Dedi Sahputra/EPA)

Singer Rihanna prepares for a photoshoot with photographer Annie Leibovitz in Havana, Cuba, May 28, 2015. (Photo by Reuters/Stringer)

The Jet Propulsion Lab team's RoboSimian robot turns on a valve at a simulated disaster-response course during day one of the Defense Advanced Research Projects Agency (DARPA) Robotics Challenge finals in Pomona, California, June 5, 2015. (Photo by David McNew/Reuters)

Well before Corey Arnold ever thought about photography, he fished. As a child, he dressed as a fisherman for four consecutive Halloweens, and once brought a dead 3-foot Mako shark to school for show-and-tell. He knew he wanted to be a professional fisherman, even if he didn’t understand what that actually meant.

Global wildlife populations will decline by 67% by 2020 unless urgent action is taken to reduce human impact on species and ecosystems, warns the biennial Living Planet Index report from WWF (World Wide Fund for Nature) and ZSL (Zoological Society of London). From elephants to eels, here are some of the wildlife populations most affected by human activity. Here: The maned wolf is among the large mammals in the Brazilian Cerrado that are threatened by the increasing conversion of grasslands into farmland for grazing and growing crops. (Photo by Ben Cranke/Nature Picture Library/Alamy Stock Photo)

A Ukrainian serviceman fires a 2S7 Pion self-propelled gun during military exercises near the village of Divychky in Kiev region, Ukraine, October 21, 2016. (Photo by Valentyn Ogirenko/Reuters)