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.

In an earlier post, we wrote about President Bush’s proposal to create the largest protected marine area in the world in the Pacific Ocean.

A group of scientists, environmental groups, and former members of Australia’s navy are now calling for the creation of another reserve that would ban fishing in a whopping 400,000 square mile area off Australia’s northeast coast.

Coral at the Great barrier reef, Australia

It will sure be interesting to see if these two suggestions will become a reality, and if so, which of the protected areas that will ultimately become the largest protected marine area in the world. When discussing protected areas it is also important to keep in mind that the term “protected” can mean very different things.

The proposed protected area off of Australia’s northeast coast is known as the Coral Sea. It is a so called marginal sea, which means that it is a part of an ocean partially enclosed by land, e.g. by archipelagos and peninsulas. The Coral Sea is bordered by the east coast of Queensland to the west, by the Vanuatu archipelago and New Caledonia to the east, and by the Solomon Islands to the north.

The Coral Sea Basin is believed to have been formed between 58 and 48 million years ago when the Queensland continental shelf was lifted up by tectonic forces. The sea is not only famous for its rich biodiversity; it is of cultural significance as well and was for instance the location of a famous battle during World War II.

The effort to create a no-take marine park in the Coral Sea is headed by the Pew Environment Group. You can find more information about the initiative on their site.