Hybrid Sharks Ready to Take Over the Oceans: Fact and/or Fiction

As much as some media outlets would like the appearance of hybrid sharks to foster new, incredible shark attacks, the reality of the situation is less fictional and simply a matter of genetics. Last week, a team of Australian scientists announced that they had found hybrid sharks, which are offspring of two different shark species that had interbred. This happened during a routine survey of Australian marine life.

These hybrid sharks resembled one species of sharks, but had genetic markers inconsistent with that specific species, implying that something interesting had happened. The subsequent investigation has revealed that these animals were hybrids between the common blacktip shark (Carcharhinus limbatus) and the Australian blacktip shark (Carcharhinus tilstoni).

The study of the hybrid sharks’ genetics has indicated that these animals are producing viable offspring and not flukes. The two species that gave these hybrids are closely related (sister species), but still distinct species. This is probably the reason why the hybridization was successful. Common blacktip sharks are much more widely distributed than the Australian backtips, but climate change has altered their breeding zones, allowing for hybrids to appear.

Sharks reproduce via copulation and internal fertilization, unlike other species of fish. Since different species of sharks have varied mating behaviors, it was previously thought that such a hybridization was extremely unlikely. These are the first hybrid sharks that have been discovered.

If these hybrids turn out to be fitter than either of their parent species, over time they might merge into a single species, simplifying their management as part of the Australian inshore shark fisheries. It will also allow for a more wider range of habitats, as the common blacktips are more temperature-tolerant, while the Australian blacktips are typically found in tropical waters.

There’s definitely no need to think that we’ll be seeing the sharks out of fiction, i.e. à la the movie Deep Blue Sea (even if those sharks were genetically engineered). While some news articles claim that these sharks were hybridized to protect themselves from climate change, this basically shows a lack of understanding of how species evolution works. Climate change can negatively affect marine organisms, but it is unlikely for a species to start hybridizing itself so that its offspring would become more temperature-tolerant. Evolution is not goal-orientated.

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