Lemon Shark in black and white

Sharks

Researchers conclude the northward range shift demonstrates the young white sharks are being subjected to a loss of suitable thermal habitat

Climate change shifts the range of white sharks

Researchers conclude the northward range shift demonstrates water temperatures within their preferred temperature range of juvenile white sharks are becoming harder to find.

The animals have historically remained in warmer waters in the southern California Current; Between 1982 and 2013, the northernmost edge of the juveniles' range was located near Santa Barbara (34° N).

The Port Jackson (Heterodontus portusjacksoni) shark is a benthic, buccal pumping species that remain motionless for extended periods of time.

Do Sharks Sleep?

Sleep is ubiquitous across the animal kingdom but despite anecdotal reports of sleep-like behaviour in nurse sharks and other seafloor-dwelling species, the question of whether sharks actually sleep has been intensely debated but remains unknown. A key criterion for separating sleep from other quiescent states is an increased arousal threshold. True sleep is characterised by a lack of movement that can be rapidly reversed, and a decreased awareness of surroundings.

Peaceful sharks

IUCN update finds sharks increasingly threatened

The Lost Shark, Carcharhinus obsoletus, is already extinct, and others that are expected to follow soon include four species each of hammerhead and angel sharks, from the world’s most threatened shark families. In spite of all the press that shark conservation has received in the past two decades, no effective protection of sharks has been established, no sharks have been saved, and their decline into extinction is ever more apparent.

The Caribbean reef shark (Carcharhinus perezi) is the most commonly encountered reef shark in the Caribbean Sea.

Reef sharks prefer small meals

Researchers from James Cook University's ARC Center of Excellence for Coral Reef Studies examined stomach contents of reef sharks and conducted chemical analyses of shark body tissue to find out what they had been eating.  

Somewhat surprisingly after pumping sharks' stomachs to identify the contents of the last meal, the most common thing to find was in fact, nothing. "These results suggest that reef sharks eat small meals infrequently and opportunistically," Lead author, Dr Ashley Frisch said.

Appeal to Shark Lovers!

The paper presents the reasons why large predators of great ecological importance cannot supply the rising demand for shark fins, which is driven by profits that rival the drug trade and involves the fisheries of nations around the globe. They have essentially run out of fish so are targeting sharks now that the shark fin trade has made them valuable.

Sharks at risk from quest to develop vaccine against corona virus

Development of a vaccine against Covid-19 could come at the expense of sharks, researchers warn; A key ingredient used in vaccines to enhance immune response and increase effectiveness, squalene — an oily substance found in plants and even human skin — is particularly concentrated in shark livers.

Salmon Sharks of Alaska

Salmon sharks lack a nictitating membrane, so their eyes can be seen following a subject, Port Fidalgo, Alaska, USA. Photo by Jennifer Idol.
Salmon sharks lack a nictitating membrane, so their eyes can be seen following a subject, Port Fidalgo, Alaska, USA. Photo by Jennifer Idol.

Sharks elicit strong emotions, be it the thrill of a planned encounter underwater or fear propelled by social media and lack of information. Of the more than 400 species of sharks, it is the small family of mackerel sharks that is most iconic. These sharks prompted me to share why one of them, the salmon shark, is an especially remarkable species.

Whale Shark
Whale Shark

Whale sharks live an incredibly long time

Many divers dream of the day they find themselves swimming beside a whale shark. Its gentle demeanour and huge size presents a unique humbling experience that is second to none.

Yet, there is much we still do not know about whale sharks.

Today, one of their hidden mysteries have been unlocked–their age.

Until recently, it was hard to fix a number to their age, as they do not have bony structures (otoliths) which are traditionally used to calculate the age of fish.