SciSun: Looking kinda’ Fishy   Leave a comment

The natural forests, rivers, meadows and other native environments that surround us are great places to hike, camp, picnic and explore, but many of the areas we now need to protect in order to save, were many years ago only temporarily ‘preserved’ from development. Over a century ago, when the modern cities we know today were first growing, community leaders and many of the ‘environmentalists’ of that day thought some undeveloped lands should be set aside for future lumber and mining and construction; not permanently protected as unique and important environments, just places that are not-yet-developed. And, by making this ‘wilderness’ available, the industrial-working-man of that time was encouraged to get some fresh air, enjoy hunting and fishing, and escape the polluted and dirty cities.

But at the Turn of the Century you couldn’t just go off into the wilderness with ‘nothing to do’; there had a be a reason for the trip and touristy activities. (we’re talking 19th Century. In the 20th century, there was sometimes TOO much to do!) So enterprising people cut holes into Giant Sequoia trees, where they built rooms and gift shops and tunnels for cars to drive through. Meadows were cleared and permanent camps built with every known comfort, so the trip into the forest wouldn’t be that much different than being at home. ‘Sportsmen’ released almost tame and easy-to-find animals into areas they knew hunters would be; and someone had the idea to stock rivers and lakes with quickly-growing, easy-to-catch, and tasty non-native fish.

Ponds and lakes, artificially filled with fish, are so popular with fishermen and weekend travelers that fish-stocking has continued from the 1850’s through today. Particularly in the Sierra in Northern California where many of the high, cold mountain ponds had no natural fish populations at all, moving millions of pounds of non-native fish, particularly rainbow trout, from hatcheries and closer to fishermen was a recreation and economic success. Today, however, scientists and researchers have discovered those fish may have caused more harm than good.

When a non-native species is introduced into a new habitat, or environment, the species probably doesn’t have any natural controls – such as temperature or seasonal changes or predators – that keep the species from increasing too fast. And the introduced species, itself, often becomes a predator to other species that before didn’t have to worry about this particular type of animal. This imbalance changes the entire ecosystem and environment. In the high, clear, fresh water ponds and lakes of the Sierra, frogs in particular had never been around large fish and over hundreds or thousands of years had become adapted to living in water that freezes every winter and has few aquatic predators. But once the fish were introduced, numbers and types of frogs began to decline. And insects – the favorite meal for frogs – started to increase. More than half of the frog populations found as recently as 1995, today are extinct and there are entire frog species, like the Mountain Yellow-Legged Frog (Rana muscosa) that are now in danger.

So, recently the National Park Service, Forest Service, and State Fish and Game Department have been removing non-native fish from the ponds and lakes where frogs and other species are endangered and reducing the number of fish stocked into other waters. They’re also moving some frogs from areas where they’re more abundant, into the ponds in more danger. Fishermen and local fishing businesses have complained these changes will be hard on them (although not as hard as it’s been on the frogs!), so for now stocking the non-native fish will continue in some, but not all, the ponds and lakes and more work is being done to protect and establish native types of fish. Because, as any fisherman knows, not all fish are the same.

Fish stocking masked  UNR

“Weee! Better than a waterpark!”

Swim on over and learn more about aquatic species of the Sierra:

http://science.nature.nps.gov/im/units/sien/monitoring/Lakes/Lakes.cfm

http://www.dfg.ca.gov/fish/resources/wildtrout/wt_nativetrout.asp

http://www.fs.fed.us/psw/programs/snrc/aquatic/research.html

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