Most may think of sharks as dead-eyed, cold-blooded killers, but it seems that they have a softer side after all. It turns out that even sharks have their own social network.
New research has found that blacktip reef sharks form strong connections with their fellow fishes. These networks of reef-mates are surprisingly resilient, remaining relatively unaffected even when up to 50 percent of the sharks in the grouping are removed. This could have significant consequences for how to better protect the vital predators as they are overfished in many regions.
“It may surprise people that sharks have social networks too,” says Culum Brown, co-author of the paper in Biology Letters, in a statement. “Sharks have traditionally been assumed to show some form of social structure only in particular situations like mating, feeding or migrations. Even though their social structure is not as complex as that of some mammals, sharks can display an affinity for one another.”
After repeated dives studying a population of sharks in the French Polynesia, the researchers were able to build a picture of the social network between 105 different sharks as they regularly interacted with each other. It is thought that these sorts of connections between individuals could help populations survive, as the fish have previously been found to display social preferences and even social learning.
But how important individuals within these systems are is little understood. This is particularly pertinent in light of heavy anthropogenic activities, namely intensive fishing, that have major impacts on these communities.
The study found that there is actually remarkable resilience within the shark network. They found that up to half the sharks could be taken from the system before it collapsed. This suggests that there are redundancies built into the social networks of the creatures, which can adapt to significant population changes.
While that should be welcome news for many worried about the impact of overfishing on the animals, the intensive fishing that sharks often face goes way above this.
Some species of shark have seen their numbers decline by 80 percent over the last 15 years, while in some regions up to 97 percent of the predators have been pulled out of the oceans. I don’t think you need a scientist to tell you how catastrophic that will be for the ecosystem in which they once swam.
