--- description: Human activity in the oceans is driving many large species toward extinction, posing a threat to the wider ocean ecosystem title: Ocean Extinction Hurts Large Animals First, Study Says image: https://static.time.com/v3/assets/bltea6093859af6183b/blted0e155eabce4003/6988a634e20a87a77aa926b2/ocean-ecosystem-fish.jpeg?branch=production&width=3840&quality=75&auto=webp&crop=16:9 ---  * [Science](/section/science/) ## Science Update your preferences in [Account Settings](/account/preferences/) Close * [Environment](/tag/environment/) ## Environment Update your preferences in [Account Settings](/account/preferences/) Close # Human Activity in the Oceans is Driving Many Large Species Toward Extinction ## Video: President Obama to Declare National Marine Monument [Watch (HLS stream): President Obama to Declare National Marine Monument](https://cdn.jwplayer.com/manifests/86NtEsmN.m3u8) (0:55)  _Published 2016-09-15. An area two-and-a-half times the size of the Grand Canyon National Park is to become the first National Maritime Monument in the U.S. Atlantic Ocean._  by [Justin Worland](/author/justin-worland/)  ## Justin Worland Update your preferences in [Account Settings](/account/preferences/) Close Senior Correspondent Sep 15, 2016 3:04 PM CUT  A school of fish swimming together underwater in the sea A school of fish swimming together underwater in the seaNoel Hendrickson—Getty Images  by [Justin Worland](/author/justin-worland/)  ## Justin Worland Update your preferences in [Account Settings](/account/preferences/) Close Senior Correspondent Sep 15, 2016 3:04 PM CUT Human activity in the oceans is driving many large species toward extinction, posing a threat to the wider ocean ecosystem, according to new [research](http://science.sciencemag.org/content/early/2016/09/13/science.aaf2416 "undefined"). Researchers behind the study, published in the journal _Science_, looked at fossil records from previous periods to compare the types of animals threatened. In the past, smaller animals tended to face greater extinction risk than their larger counterparts. Today, that has been flipped thanks largely to human fishing and hunting. And the problem has only worsened in recent years as technology has allowed humans to hunt for animals further from the coast and in deeper waters. “We see this over and over again,” says study co-author Noel Heim, a researcher at Stanford University. “Humans enter into a new ecosystem, and the largest animals are killed off first.” **Read More**: [An Underwater Investigation of Coral Bleaching in the South Pacific](http://time.com/coral/ "undefined") Researchers note that climate change is not the primary driver of mass extinction in the oceans. The threat to large animals could create problems for the ocean [ecosystems](http://time.com/4404981/biodiversity-study-human-welfare/?iid=sr-link4 "undefined") that rely on large animals as their anchor. Large animals sit at the top of the marine food chain help cycle nutrients through the water, according to the study. On a broader scale, the extinction of large marine mammals could lead to a new geological period [defined by human influence](http://time.com/4475604/the-anthropocene-should-bring-awe-and-act-as-a-warning/ "undefined"). 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