It’s Hard Out There for a Fish

2883695312_1f25da6d3d_m.jpgOftentimes we mock obscure scientific studies as fraudulent, foolish, or futile. But the reality is, much comes from studying the world around us. Case in point, the Pacific Ocean Shelf Tracking Network.

Using ever teenier and tinier transmitters, marine scientists are getting a much better understanding of the life cycles of salmon, sturgeon, trout, rockfish, and a slew of other crucial fish species. The tiny transmitters are inserted into baby fish and the network then tracks the fish pings as they grow and go through their aquatic life cycle.

All ready important data has emerged, as well as new theories on the changes in migrations due to ocean warming.

Among the findings:

• Previously, it was thought that the highest mortality rates for salmon were in the freshwater streams and rivers as they headed to the saltwater ocean. But using the acoustic tracking system, researchers found that within the first few weeks of entering the ocean, 40 percent of the salmon died. Meanwhile, billions of dollars have been spent to increase in-river survival rates of salmon through projects such as habitat improvements in spawning areas and the modification of hydroelectric dams.

• A study by Welch, which has touched off a major scientific debate, found dams may have less of an impact on salmon survival rates than previously thought. The study found juvenile salmon from the Columbia River, with its string of massive hydroelectric dams, survived their downstream migration equally or better than those migrating downstream in the dam-free Fraser River in British Columbia. Some environmentalists have insisted the only way to restore the Columbia River runs is by breaching four dams on the lower Snake River, a major tributary of the Columbia.

• It’s long been thought green sturgeon from the Sacramento and Klamath rivers in California migrated into the ocean but didn’t go far. Now, using the acoustic tracking system, the green sturgeon have been found congregating off the north end of Vancouver Island at certain times of the year and then heading into the North Pacific. They’ve also been found in Puget Sound.


And there’s more to come:

Eventually, the Census for Marine Life hopes to establish a global Ocean Tracking Network, or OTN, that would cover 14 areas in the Pacific, Atlantic, Indian and Arctic oceans, along with the Mediterranean Sea.

Efforts to establish such networks are already under way in eastern Canada, South Africa and Australia. In Australia and South Africa, the networks could also be used to alert authorities when sharks are near swimming beaches.

Kokanee Salmon Fall Spawning Run courtesy of Utah~Dave AA7IZ

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