Marine environments are typically considered more open than those on land when it comes to animal movement. On land, the range of a species can be limited by geographic features like mountain ranges, canyons, rivers, and anything else that might get in the way. In the ocean, however, actively swimming animals like, say, large sharks have few physical barriers and may instead be restricted by their own environmental preferences. This is why in unusually warm summers you might see tropical fishes in southern New England. Because of this, one of the anticipated consequences of warming ocean temperatures is shifting distributions of mobile and highly migratory species. Basically, changes in temperature are likely to allow marine animals to move into places they haven’t before, and if those temperature changes become consistent, these species might make regular visits or even just start staying there.
This kind of change is already happening and has been documented across a variety of marine species. Now, findings from a new paper in Scientific Reports by me and co-authors from the North Carolina Division of Marine Fisheries, Simon Fraser University, and East Carolina University show an apex predator may be joining the northward shift.
Juvenile Bull Shark captured in Pamlico Sound, North Carolina. Photo from the Smithsonian Environmental Research Center.
Did you know that some shark populations have declined due to overfishing? Did you know that some once-declined shark populations have recovered? If you’re like my twitter followers, it’s likely that you’ve heard the bad news, but have not heard the good news.
Why does this matter?
It’s important to share bad news so that people know there’s a problem, and that we need to act to solve that problem. However, it’s also important to share good news so that people know that a problem is solvable! This idea was behind the birth of the #OceanOptimism online outreach campaign.
Jeremy Wade and a "river monster". Image from treehugger.com
Over Memorial Day weekend, Animal Planet aired a marathon of it’s new hit show “River Monsters”. The show focuses on self-described “biologist and extreme angler” Jeremy Wade’s attempt to find some of the largest freshwater fish on Earth. I’ve heard good things about the show in the past but had never seen it before. After discovering that there were two episodes that dealt with bull sharks, and I immediately DVR-ed them to make sure I didn’t miss anything. I was absolutely shocked at what I heard Jeremy Wade say about sharks: