Up to 50 lungfish, some of them up to on metre long, was killed when tonnes of water was released from an Australian dam this week.

The water was released from the North Pine Dam in southeast Queensland between Monday morning and Tuesday night as heavy rains were threatening to overfill the dam.

According to SEQWater, who manages the North Pine Dam, up to 100 native fish went with the release, including roughly a dozen lungfish. SEQWater spokesman Mike Foster said staff were on the scene at every dam release to check for “fish kills” and that they had rescued a handful of lungfish from pools. He also stated that staff would return on Thursday [today] to see if more could be done.

In May, when the North Pine Dam opened its gates for the first time in many years, up to 150 lungfish were rescued.

Roger Currie, spokesman for the Wide Bay Burnett Conservation Council, said conservationists on the scene during the most recent water release had found up to 50 lungfish that had been killed or mutilated as a result of the release.

“Some were found caught in trees yesterday and last night,” Currie said. “They’ve just been pummelled by the sheer force of it.”

The Wide Bay Burnett Conservation Council is pushing for a study to find out how large the North Pine Dam lungfish population is, and the council is also calling for measures to protect fish during water releases.

Lungfish of the species Neoceratodus forsteri.
Copyright www.jjphoto.dk

What’s so special about the Australian lungfish?
The Queensland lungfish, Neoceratodus forsteri, is the only now living member of the family Ceratodontidae and order Ceratodontiformes. Also known as Australian lungfish or Barramunda, Neoceratodus forsteri is native only to the Mary and Burnett river systems in south-eastern Queensland. It has however been introduced to several other Australian rivers south of this area during the past century.

Fossil records of the lungfish group date back 380 million years to a period when the higher vertebrate classes were at the starting point of their development. Prehistoric fossils unearthed in New South Wales are almost identical to the now living Qeensland lungfish, indicating that this species hardly has evolved at all during the last 100 million years. Lungfishes flourished during the Devonian period (c. 413-365 million years ago) but only six species of freshwater lungfish remain today; one in Australia, one in South America, and four in Africa.

The Queensland lungfish can survive for several days out of water, but only if kept moist. It can breathe oxygen directly from the air using its lung-like swim bladder. This species is remarkably long-lived compared to most other fish species and will usually attain an age of at least 20-25 years if it manages to survive into adulthood. Granddad, a Queensland lungfish living at the Shedd Aquarium in Chicago, is at least 80 years old. He has been housed at the aquarium since 1933 and seen many generations of zoo keepers come and go. The largest

A study published in the online scientific journal PLoS Biology on October 27 with the provocative headline “Dams make no damn difference to salmon survival”[1] is now being questioned by a number of scientists, including several co-authors of the study.

According to the study, young fish running the gantlet of dams on the Snake and Columbia rivers did just as well as youngsters in an undammed river. Dams are widely regarded as one of the main reasons behind the sharp decline of salmon in North America’s western rivers and a study claiming that dams make no damn difference for salmon survival is therefore destined to receive a lot of attention from dam proponents and dam critics alike.

While a number of scientists, including several co-authors, are questioning the results and cautioning about what conclusions can really be drawn from them, lead-author David Welch stands by his report. “We’re not saying that the dams have never had an effect,” says Welch. “What we all have to ask ourselves is, if survival is up to the level of a river that doesn’t have dams, then what’s causing survival problems?”

Welch has already warned against overstating what the study proves, and continues to do so. According to Welch, the results of the study do however suggest that dams might not play such a big role in the fate of endangered Columbia River salmon today, and that the situation in the ocean – where the salmon live until it migrates upstream to spawn – is of higher importance than river conditions.

Michele DeHart, manager of the Fish Passage Center[2], strongly disagree with the conclusions drawn from the study. “There’s a huge mass of scientific literature that documents the impacts of dams. It’s just huge,” says DeHart. “It’s like saying, ‘Gosh, I just did this comparison and smoking does not cause cancer.’ Would you change your mind?”

In the study, the survival rate of young salmon and steelhead heading for the ocean (so called smolts) was measured in the rivers Columbia and Snake, which are heavily dammed, and in Fraser River, which has no dams at all. To the researchers’ surprise, the recorded survival rate was around 25 percent for all smolts, regardless of whether they travelled in dammed or undammed waters. If you take into account that smolt in the Columbia River actually have to travel a longer distance, it even looks as if smolt traversing dammed waters are doing better than their counterparts in the undammed Fraser.

Environmental groups are now claiming that comparing the different rivers with each other is like comparing apples and oranges, and co-author Carl Schreck, head of the Oregon Cooperative Fish and Wildlife Research Unit at Oregon State University, warns that the study could have failed to account for fish that die in the ocean due to the stress they have been subjected to while traversing dams in Columbia and Snake.

Ed Bowles, biologist and head of fisheries for the Oregon Department of Fish and Wildlife, says that it would be better to compare how similar fish, e.g. spring Chinook, do when they spawn in the same river – some above dams and some below.

Regular salmon

Biologists keeping track of the sockeye salmon populations in central Idaho (Sawtooth Mountains) have good news to report. More sockeye than in any other year in the last two decades have made their way pass the eight dams on the Columbia and Snake rivers and returned to idaho. 507 fish have been counted so far. That might not sound much but considering that the number has been in the single digits each of the last five years and that only 16 wild sockeye returned between 1991 and 1998 it is a large improvement. It might however be too early to start celebrating as 257 sockeye returned in 2000 followed by a number of bad years.

The improvement is believed to be due to the fact that 180,000 smolts were released in Idaho lakes in 2006. Some of the returning fish are likely artificially spawned at the Eagle Fish Hatchery in Southwestern Idaho as part of a program to help boost the sockeye populations around the Sawtooth Mountains.

The 507 returning fish might be a better number than in many years but it is still no where near the historical levels of Sockeye salmon that once wandered the 900 miles from the Pacific Ocean to Idaho lakes like Redfish, Pettit and Alturas. As many as 35,000 sockeye used to return each year. The population decline is believed to be primarily due to four dams along the lower Snake River in Eastern Washington.

Giant Mekong catfish. Copyright www.jjphoto.dk

According to Zeb Hogan, head of the National Geographic Society’s Megafishes Project, a new dam project planned for Khone Falls in Laos threatens the migration of the Mekong giant catfish. The largest Mekong giant catfish ever caught weighed in at an astonishing 293 kilograms (646 pounds), but the existence of this magnificent species is unfortunately threatened in the wild and it is currently listed as critically endangered by the World Conservation Union.

You can find out more by visiting National Geographic at http://news.nationalgeographic.com/news/2008/04/photogalleries/catfish-pictures/

The Mekong giant catfish inhabits the Mekong River Delta in South-East Asian and can be found not only in Laos, but also in nearby Cambodia. Earlier, the species lived in Thailand as well but it is now believed to have become completely eradicated from the Thai part of the Mekong River Delta. (It has however been introduced as a sport fish in a number of lakes in Thailand, so the species has not vanished completely from Thai waters.) The situation is critical for the populations in Laos and Cambodia as well and the new dam might worsen an already precarious situation. The primary threats against the Mekong giant catfish are habitat destruction, pollution and over fishing. You can find more information about the Mekong giant catfish here: http://www.aquaticcommunity.com/catfish/giantmekong.php