Bar jacks use sharks as stealth cover in hunting strategy
The bar jack (Caranx crysos) is a small yet cunning fish. According to the journal Ecology, predatory fish use sharks to hide their presence from potential prey. Videos taken by divers and remotely operated underwater vehicles revealed 34 examples of bar jacks using this hunting strategy.
Scientists from the University of Edinburgh and Italian research institutions observed the unusual behaviour of bar jacks (Caranx crysos) in the Mediterranean Sea. These small predatory fish use sharks, specifically the sandbar sharks (Carcharhinus plumbeus), as cover while hunting smaller fish species.
The research published in "Ecology" revealed that bar jacks follow sharks for about 30 seconds before launching an attack on their prey. Videos taken off the coast of the Italian island of Lampione showed 34 instances of this behaviour.
Bar jacks surprise their prey
Analysis of the video footage suggests that bar jacks, which usually hunt in small groups, are more likely to surprise their prey and have a higher chance of success if they follow sharks. When bar jacks hid behind a shark, the prey noticed their approach only in about 10 per cent of cases.
According to scientists, following sharks not only increases the hunting success of bar jacks but also protects them from other predators. Additionally, thanks to the water movement caused by sharks, bar jacks conserve energy.
According to Professor Fabio Badalamenti from the University of Edinburgh and CNR-IAS in Palermo, the research illustrates how species interactions influence hunting variations in marine ecosystems, broadening our understanding of marine biodiversity and stressing the importance of conserving top predators such as sharks.
Excessive shark fishing
Dr. Carlo Cattano from Stazione Zoologica Anton Dohrn points out the ecological significance of shark aggregations, which can impact the structure and functioning of ecosystems.
Lampione Island is one of the two known places in the Mediterranean Sea where sandbar shark aggregations occur. The expert noted that the ongoing overfishing is driving large shark populations down, putting these aggregations at risk and potentially harming other marine life.
