Fish

The Atlantic molly, a Mexican cavefish which developed resistance to a fish toxin
The Atlantic molly, a Mexican cavefish which developed resistance to a fish toxin

Fish evolution by religious selection

For centuries, the Zoque people of southern Mexico would venture each year during the Easter season deep into the sulfuric cave Cueva del Azufre to implore their deities for a bountiful rain season.

As part of the annual ritual, they release into the cave's waters a distinctive, leaf-bound paste made of lime and the ground-up root of the barbasco plant, a natural fish toxin. Believing the cave's fish to be gifts from their gods, they scoop up their poisoned prey to feed upon until their crops are ready to harvest.

Decisions reached through consensus are often more accurate, because they efficiently utilize the diverse information possessed by group members
Decisions reached through consensus are often more accurate, because they efficiently utilize the diverse information possessed by group members

Fish Choose Their Leaders By Consensus

Small groups of sticklebacks (Gasterosteus aculeatus) reach consensus when choosing which of two replica fish to follow. As group size increases, the fish make more accurate decisions.

"It turned out that stickleback fish preferred to follow larger over smaller leaders," said Ashley Ward of Sydney University

"Not only that, but they also preferred fat over thin, healthy over ill, and so on. The part that really caught our eye was that these preferences grew as the group size increased, through some kind of positive social feedback mechanism."

Japanese Tuna Scandal Deepens

In what Australian officials called an outrageous fraud, Japanese fishers probably used a series of disguises for the overcatch and international investigations have found.

The fishers described southern bluefin tuna as a different species and evaded any inspection on shore, underreported the amount of the fish they caught, and imported it as different tuna either transhipped at sea from foreign vessels or in containers. In a review that the Japanese government has vetoed from public release, investigators found the fraud extended to consumer markets.

Fish have natural rhythm to avoid predators

A study published in Nature demonstrates that fish have a natural rhythm that could help them avoid being eaten by predators

A team from the University of California led by Dr Mu-Ming Poo made the discovery during experiments with zebrafish, a type of minnow. They discovered that the larvae of the fish, which were trained to flip their tails every time a light flashed at six-second intervals, "remembered" the rhythm even after the flash was turned off.

The reason why the fish kept time was a mystery but it could be to help it keep track of time and defend itself.

Mangrove Rivulus , Rivulus marmoratus. Scientists have now found that this fish, already famed for its bizarre sex habits and ability to survive extreme conditions, does something never seen before: hangs out inside deadwood for months at a time to survive dry spells.
Mangrove Rivulus , Rivulus marmoratus. Scientists have now found that this fish, already famed for its bizarre sex habits and ability to survive extreme conditions, does something never seen before: hangs out inside deadwood for months at a time to survive dry spells.

The fish that lives in trees and breeds without a mate

The mangrove rivulus, also known as the mangrove killifish, is native to the Americas and is about five centimetres (two inches) long.

The fish has long been studied for its many unique features. It's the only vertebrate known to naturally self-fertilize, for example. In some populations, it can become a hermaphrodite, developing both male and female parts simultaneously, to produce clones of itself.

EU alarmed over cod

In the case of cod in the North Sea, eastern channel and Skagerrak...things took a turn for the worse in 2008, when a greater proportion of the stock was caught than in any year since 1999," the European Commission said in a statement.

"We are not that far away from a situation of complete collapse," said Jose Rodriguez, a marine biologist with the environmental group Oceana.

Conservation measures for desperately depleted cod have not delivered the promised revival of supplies – partly because of continued over-fishing exceeding agreed quota limits.

Atlantic Cod
Atlantic Cod

Atlantic cod survive without 'vital' immune genes, say scientists

According to an analysis of the Atlantic cod’s genome, scientists have discovered the fish have evolved to survive without a set of genes thought essential to the immune system. It is hoped the finding will lead to better vaccines for farmed cod and even open new avenues of medical research for human disease.

This goby is only found in the Benguela ecosystem, one of the world’s most productive fisheries area.
This goby is only found in the Benguela ecosystem, one of the world’s most productive fisheries area.

Fish holding its breath

The unique fish is called the Benguela-goby, or bearded goby, and is found only on the anoxic continental shelf outside Namibia and South-Africa. Since the collapse of the sardine fisheries, this goby has become the new predominant prey species for larger fish, birds and mammals in the region

The endangered Spotted Handfish are found on sandy sediments at the bottom of Tasmania's Derwent estuary and adjoining bays.

Nine new species for disappearing handfish family

The review of the handfishes brings the family to 14 known species – six found only in Tasmania and one known from only one specimen possibly collected in Tasmania by early European explorers, yet not recorded since. It also deepens concerns about the declining populations of some handfishes.