Fish

Claire Paris (second from left) and co-author Jean-Olivier Irisson (third from left), deploying the Drifting In Situ Chamber (DISC), equipped with an imaging system, during an expedition at the Australian Museum Lizard Island Research Station
Claire Paris (second from left) and co-author Jean-Olivier Irisson (third from left), deploying the Drifting In Situ Chamber (DISC), equipped with an imaging system, during an expedition at the Australian Museum Lizard Island Research Station

Fish larvae use external clues to find their way

In this study, researchers discovered that fish larvae around the world used external cues like the sun, Earth’s magnetic field and sounds to find their way around in the open ocean. 

The fish larvae were able to control their destination and migrate by keeping a bearing. 

Why puffer fish spawn on beaches under moonlight 

At the time of the spring tide (new moon and full moon), thousands of puffer fish around the world head for the coastlines to spawn. There, they gather at the water’s edge and vigorously tremble their bodies to spawn.

Scientists have long wondered how the puffer fish were able to synchronise their spawning with the lunar cycle.

A paper published in a recent issue of the Current Biology journal has the answers. 

Moray Eels

Green moray. Photo by Nigel Marsh
Most morays reside in tropical or subtropical waters, but the green or yellow moray lives in the temperate waters of Australia and New Zealand.

Aside from sharks, moray eels are one of the most maligned and misunderstood of all marine animals. Thought by many to be highly dangerous because of their depiction in films and books, morays are not malicious monsters, but important predators of any healthy marine ecosystem. They are generally shy and docile if not harassed. Nigel Marsh shares insights about these animals.

The mahi-mahi were tagged before being released back into the ocean.
The mahi-mahi were tagged before being released back into the ocean.

Fish behaviour affected by exposure to crude oil

The 3.19 million barrels of crude oil that spilled into the Gulf of Mexico during the Deepwater Horizon in 2010 had a devastating impact to the natural environment, as well as the people and animals in the vicinity.

A study on the mahi-mahi in the nearby waters revisits the incident by studying how fish in the wild are being affected from the exposure to crude oil.

Corals on Flynn Reef, part of Australia's Great Barrier Reef
Corals on Flynn Reef, part of Australia's Great Barrier Reef

Temperature and habitat changes have impacted Australia's reef fishes

For more than a decade, some researchers in Australia have been monitoring coral reefs in the vicinity to see how rising ocean temperatures affect both the tropical and temperate reef fish communities.

The findings of their study was published in the Current Biology journal.

According to lead author Rick Stuart-Smith, a marine ecologist at the University of Tasmania, the team had focused on reef fishes as reefs provided many benefits to people and the fishes there helped maintain the natural ecological function of the reefs.

Neon goby - Elacatinus oceanops
Neon goby - Elacatinus oceanops

These reef fish decide when their embryos hatch

A study in the Proceedings of the Royal Society B Biological Sciences journal has found out that the ideal time for neon goby embryos to hatch is within two hours of sunrise.

For coral reef embryos, this knowledge is important as the time of their hatching is a perilous time that directly affects their survival. Yet many of them have to decide on their own when to hatch, according to corresponding author John Majoris, a research scientist at The University of Texas at Austin.

But not for neon goby embryos.

Fathead minnow
Fathead minnow

Minnows can manage drastic temperature increases, study shows

Like other fish, minnows can adjust their body temperatures to match that of their surroundings.

Research into the effects of climate change on fish generally focus on their heat tolerance at an increase of two or three degrees Celsius above the current average temperatures.

However, a recent University of Illinois study wanted to find out how fathead minnows handled short-term temperature spikes—those amounting to as much as 5 to 10 degrees Celsius above average.

Seeking Eye Contact: Fish Gaze Reveals Self-Awareness

For many years, I held a weekly feeding session for the resident reef sharks and their visitors in the study area where I observed their behaviour. If I had enough shark food, I would scatter crumbs into the water for the fish after the sharks had left. The fish knew this, so they had to wait, and while they were waiting, they were excited.

Motorboat in the Caribbean
Motorboat in the Caribbean (Flickr/CC BY-NC-ND 2.0)

Coral reef fish breed better with less motorboat noise

They then followed the breeding of spiny chromis and discovered that 65 percent of nests on quieter reefs still had offspring at the season’s end, compared to 40 percent on reefs with a lot of motorboat traffic. On quieter reefs, offspring were larger, and each nest had more offspring by the end of the season.

Some juvenile fish on coral reefs exposed to motorboat noise have stunted growth and may be half as likely to survive as fish on quieter reefs, owing to the noise pollution altering their parents' caregiving behavior, said the researchers.