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Friday Fishy News - September 7


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Fish lips: Putin kisses sturgeon

Google News - AFP

September 1

Politicians love to be shown kissing babies, but Russian President Vladimir Putin took on an altogether more slippery customer Friday by puckering up for a fish.

The Kremlin leader, who is due to step down at the end of his second term next March, looked every bit the seasoned campaigner when he lifted the sturgeon at a fish farm in southern Russia and gave the creature a peck on the head.

Onlookers at the farm in Selo Ikryanoye, near Astrakhan on the Caspian Sea, applauded when Putin, who was wearing white gloves, then dropped the sturgeon into the sea.

The fish farm is part of efforts to regenerate the Caspian's endangered sturgeons, prized for their tiny black eggs used to make caviar.

Unique fish fossil in northern Alberta may help explain migration patterns

The Canadian Press - Google News

September 5

They went drilling for oil in northern Alberta and instead dug up a one-of-a-kind, 96-million year-old fossilized fish small enough to fit in your palm, but big enough to yield clues on how sea critters migrated in the age of Tyrannosaurus rex.

But to fish paleontologist Alison Murray, the Tycheroichthys dunvenganensis is also a big question mark.

"It's complete fossil, which means it must have been killed and buried very, very quickly," said Murray, who now researches at the University of Alberta.

"It wasn't scavenged or broken apart in wave action. It must have been some sort of sudden event that killed it and trapped it in mud."

But based on the biology of its living relatives, the herring family, it is not the type of fish to have swum in muddy waters, she said.

"So I'm not sure what it was doing there. He is an anomaly."

It's a member of the extinct fish family Paraclupeidae. While other members of this family have been found in Lebanon, Morocco and Brazil, the Alberta find is a new genus entirely.

The fossil, written up recently in the Canadian Journal of Earth Sciences, was actually unearthed two decades ago south of Grande Prairie in a core sample taken 1,325 metres below the surface by now-defunct Cequel Energy Inc.

The fish was not found because Cequel was not interested in the sediment at the bottom of the core sample.

It wasn't until a couple of years ago that geology student Michael Hay, checking out the core samples for his own research, came across the fossil and passed it on to Murray and others.

It is now at the Canadian Museum of Nature in Ottawa.

Murray said it was swimming in a monster seaway that had cleaved what is now North America in two in the late Cretaceous period.

She said the find is further evidence of a direct water link between North America through Great Britain to the Mediterranean Sea, but also gives give credence to the theory of a direct water link from the Mediterranean through what is now Hudson Bay.

"This one could support the Hudson Bay theory. We actually don't have the answer."

She said the fish will also aid research in biogeography, to help understand how organisms evolved and moved into different areas.

Coral Reef Fish Harbor An Unexpectedly High Biodiversity Of Parasites

Science Daily

September 5

IRD researchers showed that Epinephilus maculates, a fairly abundant species of grouper off New Caledonia, was parasitized by 12 species of microscopic monogenean worms. This diversity of parasites has just been confirmed also in the malabar grouper, Epinephilus malabaricus, another the coral reef species. If such a level of parasite diversity prevails in all coral-reef fish, tens of thousands of parasite species are in this ecosystem waiting to be discovered.

In the same way as the tropical rainforest, the coral reefs of warm seas are among the richest ecosystems of the world in terms of their biodiversity. In fact the best conserved areas harbour over 700 species of coral, 600 species of mollusc and nearly 4000 species of fish. These fish have been well studied by reef biodiversity specialists over the past few years, yet still little is known about their parasites. Two studies conducted by IRD researchers of Noumea have brought out evidence of this parasite species richness in two grouper species of the New Caledonian coral reef.

The new species described by the IRD taxonomists are microscopic animals less than 0.5 mm long. These tiny parasitic worms all belong to the class of monogeneans (Monogenea). They live on gills of marine fish where they find both refuge and food. Identification of each taxon is facilitated by the morphology of the genital apparatus which is characteristic for each species.

In 2006, researchers from the research unit "Systématique, Adaptation, Évolution" (UMR 148) at Noumea first studied Epinephelus maculatus, a grouper species commonly called "loche grisette" and quite common in the New Caledonia lagoon. Microscopic observation of nearly 800 specimens of monogeneans collected from gills of 10 individuals of this fish allowed biologists to identify 12 different species. By comparison, the Mediterranean grouper (Epinephelus marginatus) are host to just four species belonging to this class of gill parasite. At least 10 of these monogeneans found in the New Caledonian "loche grisette" are strictly specific: they live exclusively on this fish.

A second investigation focused on the malabar grouper (Epinephelus malabaricus, "mère loche"). It confirmed the diversity of monogenean gill parasites of the New Caledonian coral reef. For this second grouper species, 11 species of associated monogeneans were identified among more than 300 collected from the gills of two malabar specimens The existence of a rich fauna of monogeneans in the New Caledonia grouper was therefore confirmed. The ensuing article gives a detailed list of 44 parasite species already recorded in the malabar grouper in the whole of the Pacific Ocean.

The malabar grouper has a high initial growth rate and the adult reaches 50 kg, making it a species highly prized by aquaculture operators in South-East Asia. Young malabar groupers are taken directly from their natural habitat in order to supply the fish farms. They are subsequently fattened up quickly, as are red tuna in the Mediterranean. As an example, the Thai production of this fish thus grew from 15 000 individuals in 1991 to 265 000 in 1995. Parasite control in such breeding conditions, where high density of fish populations favours high rates of parasite infection, is crucially important, as the parasitized specimens usually have a lower than average growth rate. Better knowledge of the parasite species present in wild malabar grouper populations could help improve rearing management.

The IRD Noumea research team also substantiated the hypothesis that reef fish in general have an especially rich parasite biodiversity. The New Caledonian coral reef harbours nearly 2000 species of fish. Extrapolation of these results to the whole of this Pacific island's coral reef yielded an estimated fish parasite biodiversity of about 10 000 species. Extrapolating again, to such an aquatic ecosystem at the global scale can certainly give a figure two or three times as large.

Biologists currently have very little knowledge about the host-parasite relation that links the monogeneans to the fish. Like all parasites, they must be closely tied with their host. The specificity the newly described monogenean species have to particular groupers shows this. The disappearance of one species of fish would threfore likely lead to that of the parasites associated with it.

Hosts and parasites form a system that reaches a certain equilibrium as evolution proceeds. Destruction of this equilibrium could influence the regulation of fish populations, in letting the less strongly parasitized species become more invasive, and modify the structure of coral reef communities. Maintenance of this ecosystem in a good state is already seriously threatened by global warming, pollution and the development of tourism. Therefore it is more necessary than ever to conserve the entirety of this natural habitat.

Low Oxygen In Coastal Waters Impairs Fish Reproduction

August 31

Science Daily — Low oxygen levels in coastal waters interfere with fish reproduction by disrupting the fishes' hormones, a marine scientist from The University of Texas at Austin Marine Science Institute has found.

Incidents of seasonal low levels of oxygen, known as hypoxia, have increased dramatically in coastal waters throughout the world over the past few decades, largely as a result of increased run-off from human agricultural and industrial activities. Hypoxia's long-term impact on marine animal populations is unknown.

Dr. Peter Thomas found that both male and female fish collected from seasonally hypoxic waters in Florida's Pensacola Bay estuaries had little ovarian and testicular growth, low egg and sperm production, and low levels of reproductive hormones during a time a year when they would normally be increasing in preparation for reproduction.

"This study provides the first clear evidence that a wild population of estuarine fish has experienced reproductive impairment through hypoxia," said Thomas, professor of marine science. "We rarely find such a dramatic reproductive impairment in both male and female fish collected from degraded environments, such as those contaminated with pollutants."

Laboratory studies showed that hypoxia caused endocrine disruption through decreasing levels in the brain of a chemical important for brain function called serotonin. The decrease in serotonin was caused by a decrease in an enzyme that plays a role in the serotonin synthesis pathway.

Atlantic croaker is one of the most common inshore fish species along the coasts of the southeastern Atlantic Ocean and Gulf of Mexico, and Thomas said that the croaker is representative of many inshore fish.

"This study suggests that when persistent coastal hypoxia occurs, there is a potential long-term threat to fish populations and fishery resources," said Thomas. "With worldwide increases in hypoxia, it's something we must be concerned about, because so many people rely on fishing for their livelihood."

Thomas' future studies will aim to further elucidate the effects of hypoxia on fish endocrine and reproductive systems at the molecular level. He is also pursuing similar work on reproductive impairment in croaker from hypoxic waters surrounding the so-called "Dead Zone" off the coast of Louisiana, which is an area of almost no oxygen that this year covered 7,900 square miles.

Thomas' research was recently published online in Proceedings of the Royal Society B.

Funding for this research was provided by the U.S. Environmental Protection Agency. Dr. Md. Saydur Rahman Dr. Izhar Khan and James Kummer contributed to the research.


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