Behaviour

Conventionally, shark behaviour has been perceived as largely instinctive and uniform across individuals. However, a team of researchers, led by Thomas M. Vignaud, have upended this notion, uncovering a spectrum of individual personalities among bull sharks frequenting feeding sites.

Researchers conducted trials using SMART drumlines in New South Wales, Australia, to catch and release sharks, particularly White Sharks. The study aimed to quantify the short-term post-release movements and the longer-term fate of these sharks.

Sharks were caught using SMART drumlines deployed about 500 meters from shore. Once captured, they were quickly secured to a research vessel, minimising potential injuries. The sharks were tagged with satellite-linked radio transmitting tags and acoustic transmitters to monitor their movements post-release.

Elasmobranchs have become lucrative targets with the depletion of traditional fish stocks and the surge in the shark fin trade. Although, in recent decades, much scientific evidence has challenged traditional misconceptions, stereotyped media portrayals persist, and they hinder conservation efforts. So, this special issue was created to highlight the complex behaviour and cognition of sharks and rays.

A comprehensive study published in the journal Marine Mammal Science analysed over 60 years of recorded interactions between Southern Resident killer whales (SRKW) and porpoises in the Salish Sea. This endangered population of orcas, known for their fish-based diet, particularly Chinook salmon, has been involved in numerous incidents of porpoise harassment, leading to the deaths of many porpoises.

Possible explanations

The study proposes three main reasons for this behaviour:

We’ve all seen those huge schools of fish that move as one and coordinate their movements so perfectly. New research has come up with a way to map the chain of direct interaction in such schools of fish, discovering that the fish pay attention to one or two of their neighbours at a time when the school moves as a group.

Two male great white sharks named "Jekyll" and "Simon", tagged off Georgia's coast in December, displayed a groundbreaking migration pattern.

From April, Jekyll and Simon's joint journey saw them traverse the Atlantic Coast, passing places like Ocracoke and Virginia Beach in a synchronised manner. While sharks sometimes gather for mating or feeding, their migrations are usually solitary.

Behavioural innovation is thought to play an important role in enabling animals to cope with environmental change. Research on animal innovation has focused on terrestrial and freshwater vertebrates, but few animals face environmental variation as extreme as those living in littoral zones, where physical and social conditions change dramatically from moment to moment.

The trumpetfish, with its long, slender body, shadows non-threatening species like the parrotfish. This allows it to get closer to its prey, such as damselfish, without being detected. Dr Sam Matchette, a leading researcher from the University of Cambridge, explains that when the trumpetfish swims alongside another species, it either remains hidden or is not recognised as a threat due to its altered shape.