Unintended Consequences Removing a Foreign Species

[archman]

Removing intrusive exotics is most successful in small, confined areas where there are oodles of people available to monitor and clean up. Basically, wherever there is extremely high human maintenance. Continuous human maintenance.

I guess such areas represent something of the order of a fraction of a fraction of a fraction of a percent of natural habitats. Commonly these places can be found wherever there is an active natural resources presence. City parks and rivers, state and federal parks, endangered species refugia, critical habitats, etc...

Helping clean out and take care of these (micro)habitats can be fun, educational, and cathartic. You get to kill stuff in the name of environmentalism.

I love it.

 

[markr]

An interesting story about an attempt to control a non-native animal involves the Hawaian islands and mogooses. Mongooses were imported to all the islands, except Kauai, to control the non-native rat population. The mongooses didn't control the rat population but did almost wipe out several native birds. While the mongooses will eat rats, apparently bird eggs are easier to catch.

 

[Hank49]

An interesting story about an attempt to control a non-native animal involves the Hawaian islands and mogooses. Mongooses were imported to all the islands, except Kauai, to control the non-native rat population. The mongooses didn't control the rat population but did almost wipe out several native birds. While the mongooses will eat rats, apparently bird eggs are easier to catch.

Yes, and this is very evident on Kauai. One of the more common birds there are feral chickens...and also ring necked pheasant. Ground birds whose eggs would easily be found by mongeese...mongooses...whatever.

 

[drbill]

Has a non native species ever been successfully removed anywhere? It seems we've had more "success" at removing (extinction) native species.

As I mentioned in my previous post, we removed all of the non-native European goats on Catalina Island. It took millions of dollars and several years (donated almost entirely by a former biology student of mine who was the chairman of the board of the Catalina Conservancy when I was Vice President). We don't expect to see another feral goat swim over to the island in the near future. However we did recently receive three racoons which are not native to the island.

Doing so in the marine environment is quite different due to dispersal of spores, larvae and adults in ocean currents. Many land plants can disperse across the Channel separating us from the mainland via wind, etc., so they pose similar problems to marine life.

By the way, Archman... I got immense pleasure ripping out all the Sargassum filicinum that invaded the dive park last summer. Killing them really made me feel good. I just wish they were more edible! I like to eat what I kill.

 

[MeiLing]

Goats are one thing. They're big! When it comes to plants, insects and other tiny animals completely removing them can be even more difficult

With the mongoose in Hawaii, I think part of the problem is they operate on different circadian rythms. Mongoose are active during the day, while rats are sleeping. Just a little oversight in the planning process there!

 

[drbill]

Agree, Lisa. Plants and algae have seeds and spores that may persist long after the mature plants are removed. They can keep coming up for decades and longer. Total removal of them is far harder than eliminating the goats (although everyone said we couldn't do it).

As you and Dave have stated, there are a lot of things to be considered in the planning process. This is why with the non-native plants ("wildland weeds") we had to find ways of prioritizing removal of the 200 or so species on our island. Ecological threat to natives and realistic chance of eradication were among the many criteria.

 

[archman]

I think I remember reading somewhere that in (south) Florida, there are more exotic species than natural ones.

And for a couple southwest desert states, there are more varieties of introduced fishes than there are native.

Does anyone have a particular exotic species that they really, REALLY hate?

My numero uno is Fire Ants. Damn do those things suck.

 

[The Chairman]

Consider the Water hyacinths here in Florida. Imported in the early 1920s for their beautiful flower, it became obvious that it's major impact was to clog our waterways. So they introduced the Nile Perch (Tilapia) because research showed that it would eat these plants. In situ, they did not and preferred what every other Floridian underwater herbivore wants: another aquatic invasive species called hydrilla.

So now we have Tilapia all over the place. However, far from being the ecological disaster that it could have been, it has had some surprising benefits. Bass love to eat them. So, our dwindling bass population has seen a HUGE boost with these readily available meals swimming around for them.

 

[Hank49]

How about the Africanized bees? Not that the bee itself is that bad, unless you upset them....but I hear that now there is a virus or something killing off honey bees in the US? Having seen the transfer of shrimp worldwide spread all the viruses and almost wipe out populations, I wonder if this isn't a bug that came in with the African bees.
Tilapia also took over the intertidal areas of a lot of SE Asia and Hawaii. t Mozambique is an especially hardy one that can live and breed in 0 - 40 ppt saltwater. I've read that some lakes in Florida that had tilapia introduced now have 90% of the fish biomass in tilapia. Africa has some badass organisms....cattle egrets, tilapia, AIDS, Ebola....

 

[Bob3]

The way California treats invasive species can sometimes be quite entertaining, such as the situation with Lake Davis & those nasty Northern Pike.
The state first partially drained & then dumped in massive amounts of poison, which promptly migrated to the nearby city of Portola's drinking water supply.
Then they were shocking & netting them, then running det cord & blasting the critters, and now they're talking about another round of poisoning - each time the local fishing - dependent business lost an entire season's worth of income.

I was kind enough to supply the DFG with the perfect solution:

Pickled Pike

Fillet & skin the Pike, then cut up into pieces.

Salt, using 1/2 cup of pickling salt to 1 quart of fish.

Put into crock and cover with cider vinegar.

Let stand 5 - 7 days in cool place.

Rinse with cold water. The fish will be very firm.

Drain well.

Heat 3/4 cup sugar & 1 cup white vinegar & 1 cup of white wine. (Gallo Blanc or similar I'm partial to White Port but it can be hard to find).

Allow to cool after all sugar is dissolved.

Pack fish in jars with lots of sliced onions. Add 1 teaspoon of pickling spices per quart. Dried hot peppers or cloves may also be added if desired. Don't forget garlic if you like it.

Pour juice over fish.

Let stand a few days before eating to blend flavors.

Keep in refrigerator until eaten.