The Northern Snakehead, or Channa argus is an exotic fish native to China and other parts of Asia. It is speculated that this breed of fish was introduced to the Chesapeake Bay area and other waterways along the East Coast through release from the fish market or pet aquariums. For ordinary fish, this would not be an overwhelming problem; they would probably succumb to their surroundings. But, the C. argus species is clearly dominant over all other fish. With its sharp teeth and growth up to 47 inches and 15 pounds, the Snakehead has been described as a “voracious top-level predator.” This means that it is at the top of the food chain in bays, ponds, and lakes, thus posing a serious threat to local fish populations. On top of this, the Northern Snakehead apparently has the ability to move short distances on land to other bodies of water.
The species was first caught in Crofton Pond, USA near Washington D.C. in 2002. Since the pond was in Maryland territory, the state government took action to poison the pond to prevent the uprising of this foreign fish. Even after this isolated incident, there have still been finds of the fish. 2 years later, in Wheaton Regional Park, Maryland, a very surprised fisherman landed a 19 inch Snakehead. The lake that it was caught in was soon drained. Still, another was caught in 2007 in Lake Wylie, North Carolina. I think that the Northern Snakehead is a serious threat to the water ecosystems of North America. More action should be taken in preventing them from entering our waters in the first place. Zoos, aquariums and wildlife agencies could buy overgrown fish from owners. Preventative measures are one possible solution to reducing Snakehead finds and protect indigenous ecosystems in the future.
The Clarius batrachus has been called the walking catfish because of its ability to use its pectoral fins to move from one body of water to another during wet seasons. In South Florida, walking catfish are very common (up to 3,000 pounds in some areas). They were first introduced in the 1960’s by the aquarium trade, and have quickly spread through the interconnected canal systems in the state, and by overland migration during rainy nights. The problem with walking catfish is that they feed on many prey, including eggs of other fish, small fish, and a number of crustaceans and other insects. This is an issue because they are competing with other native species for food and space, and as their numbers increase, they can eliminate native species.
Before I joined this class, I had no idea what invasive species were. In fact, when I lived in South Florida, I actually came across this species of fish in aquariums and lakes, but had no idea that they were an invasive specie. The information presented in this article not only makes me realize that invasive species are all around me, but it opened my eyes to the reality of invasive spcies. Even as I learn about invasive species in class, I tend to think of them as nasty, ugly looking critters, such as the didymo we learned about today, when in fact, that is very far away from the truth. Walking catfish are actually quite interesting looking; they are grayish/yellowish in color and have mustache’s (called barbles) that attract many tourists in aquariums. To people that lack knowledge of invasive species, these creatures can become very appealing, which in turn, makes it a difficult issue to deal with. Therefore, the best way to prevent the spread of invasive species is to make people aware of their presence.
If you want to learn more, here’s the article where I found the information.
In a 2008 National Geographic article, Willie Drye describes a fire likely started carelessly in the Florida Everglades. Under normal circumstances, the wet and swampy marsh area would not be greatly affected. However, the presence of Melaleuca quinquenervia, or the melaleuca tree, significantly increased the risk of fire damage. The melaleuca tree, a native of Australia, was brought to the South Florida region in the late 19th and early 20th century. The tree absorbs large volumes of water, which means the tree was originally intended to dry up the swampy land and use it for development in the area. However, the trees now displace native species (Environmental News Service) in the Everglades and exacerbate the risk of fire. Melaleuca is known for its paper-like and thus flammable leaves.
Many attempts to eradicate melaleuca trees have been made since the 2004 Environmental News article was published,. Aerial herbicide has been sprayed over the Everglades and three species of insects have been introduced (primarily the melaleuca leaf weevil) to eat the leaves of young trees to hinder their growth. Another method, which initially may seem like a simple and effective solution, is cutting down the trees. Because melaleuca contain capsules with millions of seeds, however, cutting them down simply causes them to fall and spread, resulting in more trees. The stress of fire causes a similar result.
Clearly, the attempts made have been insufficient. The four year time difference between these two articles illustrates that although the government is working diligently to stop this problem, little progress is being made. The two measures currently in use may keep the growth under control but are not enough to completely rid the area of the species. Furthermore, the long term effects of adding yet another invasive species (the weevil is also Australian) to the Everglades are unknown. Similarly, the aerial herbicides may have negative effects on native plants in the area. Long term and permanent solutions need to be developed. As a South Florida resident, I have driven on the highway by the Everglades and seen fires in the distance several times during the dry season. It is a disappointing site because the Everglades contains such diversity and beauty and should not be unnecessarily burning down. This is a pressing issue that must be solved.
Wildlife activists and state officials are teaming up in the attempt to control and eliminate the noxious Eurasian water milfoil recently discovered in Montana. This invasive aquatic weed has continued to cause problems for local fisherman and boaters due to its’ characteristic behavior of forming a think layer of weeds on the surface of the water. As a result, sunlight can no longer permeate through the surface, and various wildlife species beneath the surface suffocate.
Efforts to control this problem include mandatory boat checks throughout the summer, frequent cleaning of boat bottoms and other fishing gear, and the spread of information regarding the effects of this non-native vegetation. According to the Wisconsin Department of Natural Resources website, the water milfoil thrives in bodies of water with a high concentration of nutrients. The author of the article continues to suggest that by integrating a watershed management program to keep nutrients out of the lakes, the milfoil colonies will be less likely to reproduce. Not only will these steps help control the problem, but manual labor consisting of physically extracting the plants out of the water and shore via rakes will also help. Another approach to eliminating the spread of the water milfoil is through mechanical cutters. On the downside, this method not only removes the unwanted milfoil canopy, but other native plants and vegetation, as well.
Various sites offered an assortment of methods for removing milfoil from bodies of water. I was relieved to find that one in particular listed a unique, alternative method of removal: biological control. Eurhychiopsis lecontei, an herbivorous weevil, is a known predator of the Eurasian water milfoil. Through this beetle’s reproductive processes, this invasive weed becomes extensively damaged. Even more, this North American native beetle prefers the Eurasian water milfoil to other native plants. As a result, fragile and native vegetation in the infested area would not be at risk during this method of treatment.
Clearly, there are more than enough ways to try and solve this epidemic. For this reason, I’m curious why this is still such an issue. The first appearance of the water milfoil in Wisconsin, for example, was in 1960. By 1993, the milfoil grew to take over 54% of the counties bays, lakes, and waterways. With the money, effort, and time being thwarted towards such a devastating weed, I would assume this problem would have been prevented in other areas. And yet, Belgrade News released an article on August 24th, 2010, announcing the invasion of this species in a Montana lake. Perhaps mere education and post-invasion clean ups are not sufficient to stop this spreading plant. The weed originated in Asia, Europe, and North America, and now appears in nearly multiple states. I suggest administering policies on the national level to prevent future spreading of this aquatic vegetation from state to state. By doing so, both the costs of restoration will be significantly minimized and overall ecosystems will be protected from this destructive, invasive, and overpowering specie.
For more information, follow the links below.
“Rock Snot.” It sounds like a gag item a 13-year old created with a chemistry set—or perhaps just the nickname he came up with to annoy his sister. The reality, however, is not funny. “Rock Snot” is actually the nickname for a freshwater algae Didymosphenia geminata, or didymo for short. How serious is it? In New Zealand, didymo is considered a dangerous enough biosecurity threat that there is a penalty of up to 5 years in jail and $100,000 for knowingly spreading it. And in North America – specifically New England – it might just be the most devastating invasive species to hit the waters of Vermont and New Hampshire since Eurasian milfoil.
Didymo is one of eight related species of algae originating in Russia’s Lake Baikal—and the only known algae to have taken on invasive characteristics. It has been found in some northern European rivers for at least a hundred years, but recently (for reasons not yet completely apparent) has begun to spread around the world widely and aggressively, preferring cold, shallow, well-oxygenated, but nutrient-poor waters (such as are common in the mountainous areas of New England). Once didymo invades a river, there is no known way of eradicating it.
What makes didymo so damaging, according to the Global Invasive Species Database, is that it “forms massive blooms that have a range of adverse effects on freshwater ecosystems, as well as human and economic effects.” In the worst case, it can grow from bank to bank across an entire stream, in a thick mat covering the entire bottom to a depth of several inches, smothering rocks and submerged plants. Studies show that hese blooms can reduce the amount and availability of suitable habitats, and when large enough mats are present, they can reduce the size of some larval aquatic insect populations, depriving fish of prey.
There has been considerable scientific study regarding the transport of this invasive species, and debate has settled upon the felt soles of fishermen’s “waders.” Fly fishermen value the felt soles for their ability to cling to rocks too slippery for normal rubbers to adhere to, but, as stated in the class article, if ever there were a perfect medium on which a microscopic invasive species could emigrate to another environment, felt would be it. In my opinion, I am shocked by the counter argument of the fly fishermen, who cite cost effectiveness and seem to belittle the issue of invasive species transport in the face of their own personal fishing success (they also claim that other parts of the boot could attract didymo, and while this may be true, felt is by far the worst material, as well as being almost impossible for a regular fisherman to adequately clean). Granted, fishermen value their pristine rivers and lakes arguably higher than anyone else – they definitely derive the most utility from them – but the fact remains that they are the source of the problem. Perhaps a regulation prohibiting felt soles for fishermen who would actually pose a risk of transporting invasive species (that is, fishermen who travel a specified distance, such as international travel) is in order. But fishermen who stay in-state don’t seem to carry any risk.
A recent article published in the Missourian addressed the issue of the invasive Asian carp and their uncanny ability to spread and completely dominate a river or lake. These fish are damaging native populations of fish because they eat plankton, a common food of all young fish, and are also endangering boaters, fishers, and even water skiers. Asian carp have a tendency to leap out of the water when a boat passes and since they have been known to reach up to 100 pounds in weight, pose a safety hazard to people and equipment alike. They are a big issue in the Kansas and Illinois Rivers, but anglers have been observed taking buckets of them as bait or even attempting to catch them when confusing them for native species. It is illegal to possess, move, or release prohibited species such as the Asian Carp, but a lack of knowledge on the part of the anglers means that this still happens.
Asian carp are clearly a serious issue and, as the title of the article alludes to, it is a lack of knowledge, the “unknowing fishermen,” who are mostly responsible for the spread of aquatic invasive species including the Asian carp. The first step to control should be prevention, which starts with education of the anglers and other persons responsible for the transportation of invasive species. It seems that few control methods have been very effective for the Asian carp without damaging many native species as well. Pesticides are always an option, but they are generally lethal for native species of fish as well. According to the article, electric currents can be used to “discourage” the spread of fish into new areas.
It seems to me that more research needs to be done about effective methods of controlling the Asian carp once it is established in an ecosystem, and education efforts need to be increased to stop the further spread of species such as the Asian carp. If anglers and boaters see the swarms of Asian carp around their boats and are told that they can help to prevent this from happening in other areas, they will most likely be willing to do their part to stop any future spread. Asian carp have been an issue in Europe for some time, so collaboration with other countries or agencies should be encouraged so that a solution can be found.
California has been struggling with the northern pike for about fifteen years. It is a large toothy fish with a voracious appetite and has caused a number of ecological headaches, especially in Lake Davis. The pike has been threatening to overwhelm native species of fish such as the trout. Local fishing businesses are centered around tourists fishing the lake’s trout population. However, the pike has caused the number of trout to subsequently plummet, which in turn, damage the businesses. and The bad publicity doubly crippled these businesses. While the owners of the local bait and tackle shops are pleased with the renewed efforts to rid the pike from the lake, many still remain hesitant.
Since the pike problem was discovered in the mid 1990′s, there have been several efforts to remove the pike from Lake Davis. For example, in 2003 state officials used an underwater explosive cable to try and blow up the fish. I’m sure many people have heard of fishing with dynamite as a fairly effective way to easily catch large amounts of fish. The explosive cable managed to bag a whopping four fish. Another effort was to poison the fish with a pesticide known as rotenone. The powder form of the poison dented the pike populations for only two years whereupon their numbers came back in force. Also, it unfortunately tainted the lake which had served as Portola’s primary water supply. The town was then forced to switch to mostly wells as their source for water.
However, a newer liquid form of rotenone holds promise. But many are skeptical that it will merely be a repeat of the poison’s previous fiasco. Officials gave it the green light anyway and started dosing the streams that feed into Lake Davis. It seems to be working fairly well and the state has plans to restock the lake with up to a million trout should the efforts prove successful. This is an article from 2007 but I have not been able to find a followup article to discover if it was successful or not. It seems as though (as is typical with many invasive species) the efforts will merely put a stall on the invasion.
In a recent article published in the New York Times titled, Pythons in Florida Stalked by Hunters and Tourists Alike, the author, Damien Cave highlights the threat of Burmese pythons to the native species of the Everglades. (This article can be found here) Over the years, these snakes that were probably abandoned by their pet owners have managed to attain staggering numbers. Some researchers estimate the population to be in the thousands. As a result of the python takeover, other species of animals indigenous to the Everglades are at great risk. These pythons eat anything from small bunnies to alligators. There have also been reports of these pythons attacking small children. Due to their aggressive nature and their potential threat to the existence of a variety of animals, hunters are being greatly encouraged to capture these beasts.
Unfortunately, the Burmese pythons aren’t the only threatening snakes to have entered the Everglades. Recently, African Rock pythons have been discovered roaming around in the Miami-Dade county. Scientists worry that these pythons could mate with the Burmese pythons and produce an even more threatening population of snakes in Florida. (This article can be found here)
I believe that one of the major issues facing the habitats of animals in the Everglades is that these snakes only represent just the surface of the harmful invasive species residing there. Snakes are often mentioned because they are large, vicious, and “cool” creatures that spark the attention of tourists. Since the Everglades has been noted to be used as a dumping ground for exotic animals, it is quite possible that there are a numerable amount of other harmful invasive species that are causing problems for native animals.
The Chinese Mitten Crab first arrived on the shores of North America in 1965. One crab, found in Ontario, resulted in widespread discussion throughout the country because no one wanted to see it spread. Unfortunately, it spread and they can be found in California, Maryland, New York, and most recently, New Jersey. In these states the crabs have caused many problems, i.e. clogging San Francisco’s water system, and now that New Jersey has become the next victim, fisherman have begun to panic. According to Gregory Ruiz “40 crabs have been caught, reported and confirmed in New Jersey alone, making that state ground zero right now for mitten crabs.” The state is trying to do whatever it can to contain the population, asking all residents to try and capture any specimen they encounter to prevent reproduction. New Jersey Division of Fish and Wildlife is trying to stop the spread now because the females can produce up to 1 million eggs per reproductive cycle, and that would not end well for New Jersey’s aquatic and marine ecosystems.
The urgency with which the state is trying to address the issue is completely rational. Hopefully New Jersey can manage the situation without it getting too out of hand. These crabs can cause serious issues to ecosystems because they are omnivores, and therefore prey on a multitude of organisms. Aside from the organisms, the crabs have destroyed the physical ecosystems in their previous homes when they burrowed into the walls of riverbanks, causing erosion. Despite Jew Jersey’s efforts, its plan is flawed because it relies so heavily on assistance from civilians. To many people the idea of seeing a live crab disturbs them, but to capture one is in a league of its own. Therefore, I believe that New Jersey should continue to encourage people, but try to unite with other states that have this problem so there can be a joint effort. Also, some people tend to work harder if there is some sort of incentive. Perhaps if a small reward were offered per crab, more people would try to catch them in hopes of profiting. In general, I just want this problem to be handled so that my home, New Jersey does not face any irreversible repercussions.