1. AQUATIC NUISANCE SPECIES
Invasive or Alien Species

2. ANS are nonindigenous aquatic species that pose significant ecological and economic threats to aquatic ecosystems. This can include fish, aquatic plants, algae, invertebrates, mussels, viruses, and other aquatic pathogens
Some things to think about:
How long before they stop being “alien”?
How long do they have to stay in the environment? People swim and interact with an environment like the sea they inhabit only part of the time as swimmers, boaters, fishermen and so on.
THE QUESTION OF INVASIVE SPECIES
Aquatic nuisance species are living organisms that have invaded a new area or environment. These may be land based or water based.
Here is a typical definition:
ANS are nonindigenous aquatic species that pose significant ecological and economic threats to aquatic ecosystems. This can include fish, aquatic plants, algae, invertebrates, mussels, viruses, and other aquatic pathogens
There are many questions about the nature of “invasive” or “alien” species. For example – how long must an organism be in an environment before it becomes “naturalized”? While we worry about the “alien” Africanized bees, few people think of the honey bees in America as being alien, yet almost all of them come from Europe. The indigenous bees went extinct and in the 17th century honey bees were brought from Europe.
We can also ask whether the organism has to “live” in the environment it has moved into. Humans have for millennia been on and in the waters of the world, but do not inhabit it full time (although some cultures of the world have people who have spent most of the lives in boats). Does the fact that humans have entered the watery environments of the world without “inhabiting” them constitute enough reason to say they are invasive there? Of course the fact that humans evolved in Africa makes them invasive virtually everywhere. Worse still an organism which “evolves” become an invasive species since it was not there previously and will certainly impact the environment in which it evolves.

3. Official Definition
As per Executive Order an "invasive species" is defined as a species that is:
1) non-native (or alien) to the ecosystem under consideration and
2) whose introduction causes or is likely to cause economic or environmental harm or harm to human health.
Aquatic Nuisance Species (ANS) are non indigenous species that threaten the diversity or abundance of native species, the ecological stability of infested waters, or any commercial, agricultural, aquacultural or recreational activities dependent on such waters.
Here is the “official definition” as found in Executive Order 13112
1) non-native (or alien) to the ecosystem under consideration and
2) whose introduction causes or is likely to cause economic or environmental harm or harm to human health.
Aquatic Nuisance Species (ANS) are non indigenous species that threaten the diversity or abundance of native species, the ecological stability of infested waters, or any commercial, agricultural, aquacultural or recreational activities dependent on such waters.
Here the key is that the introduction of the organism must impact humans in a negative way. So the definition is very “human centric”
None the less, the official definitions define legalities and this is where the Coast Guard becomes involved. Once there is a legal issue concerned, then governmental agencies can take action.
From this we can see that an “Invasive species” need not be a nuisance species. Only about 15% of invasive species are problematical. Many cannot survive in their new environments and of those that do, they cause no problems. In some cases, in fact “alien” species have been introduced to curtail a different species in the area, although this has not been successful in most cases.
The big concern is that as animals evolve in s system, they have time to adjust to changes going on. The introduction of an “alien” life form can result in a situation where there is not enough time for other species to adapt to the newcomer and hence, the ecological balance such as it is may be destroyed causing hardship and problems for people in the area.

4. Chinese Mitten Crab (Eriocheir sinensis)
This slide starts the series of photos and verbal information concerning some of the various organisms which have been defined as “Aquatic Nuisance Species”
Here is the Chinese mitten crab which is East Asian in origin. In 2007 the first one was found in the Hudson (Tappen Zee Area). They have been found in areas now. They first appeared in the East in the Great Lakes - St. Lawrence area in the 60’s but seemed not to establish themselves there, although recently there has been an increase in numbers. They are found down to Chesapeake Bay. They live in salt and fresh water and can make their way on land as well. They are aggressive and compete with the native blue crab. They also burrow, which makes for problems with stream bank and earthen dam stability which can become compromised.
They may have come in ballast or through live release
They are the only freshwater crab in the Hudson River drainage
Claws equal size with white tips and hair
Carapace (shell) up to 4 inches wide; light brown to olive color
Eight sharp pointed walking legs; no swimming legs
If you catch a Chinese mitten crab
Do not release it back to the water
Keep it and freeze it (preserve in alcohol if you can't freeze it)
Note date and location caught (GPS coordinates preferred but pinpointed on a map is acceptable) and how you caught it
If possible, take a close-up photo. You may photo to for identification.

5. Northern Snakehead Fish (Channa argus)
In China Korea and Russia this fish is not an alien. Some are also found in other Asian countries and part of Africa.
As an invasive species it is found in Ridgebury in Orange County and also in Queens. The Queens population is in a confined body of water, the Orange County one is not. It is connected to the Wallkill River drainage area and could potentially find its way to the Hudson River, the Great Lakes and the continental US,
They are voracious eaters, eating fish, frogs, crayfish and aquatic insects. They are capable of breathing air and can live out of water for days.
There are plans to use rotenone a naturally occurring pesticide in the Ridgebury, Orange county population of these fish
What do they look like?
Tan to pale brown with dark brown blotches on sides and saddle-like markings on back.
Elongate body with long dorsal and anal fins.
Many sharp teeth.
Large mouth reaching far behind eyes.
May be confused with bowfin which has a short anal fin, small teeth and often a black spot at base of tail.
What should I do if I see or catch a snakehead?
REPORT any caught or observed snakehead to DEC's regional fisheries office.
If you catch one, DO NOT RELEASE it. Kill it immediately, freeze it and report your catch. Take a digital photo if possible

6. The sea lamprey (Petromyzon marinus)
Although the first sea lampreys were spotted in Lake Champlain in 1929, genetic evidence indicates that the lamprey may in fact be native. There are 4 lampreys in the lake including this one. Two are non-parasitic and one is but it doesn’t seem to have a significant impact on the fish communities in the lake.
The lamprey is a jawless fish (agnatha – without jaws) which has been found in Lake Champlain. They attach to a fish by suction and use their sharp rasping teeth to bore a hole in the fish. They often attach to lake trout and salmon reducing their populations. Attempts to restore the populations of these fish have not been very successful.
Forty to sixty % of the fish attacked die. It has been estimated that 29.4 million dollars in business has been lost because of the sea lamprey.

7. Didymo (Rock Snot)
This unpleasantly named bit of vegetation, is a diatom – a microscopic organism which is capable of producing large quantities of stalk material that becomes thick brown mats on the stream bottoms. Native to the US, but not in the East, it has moved both West and East of its original habitat. It grows in both flowing and still waters. It undergoes “blooms” which produce the mat like growth. This chokes organism living on the stream bottom and thus impacts the food supply of the trout and other fish. For people going into the water, it makes footing very insecure.
How do I know if I find didymo?
Color - tan, brown or white (not green); may form long white "tails"
Texture - like wet wool (not slimy)
Strength - firmly attached; does not fall apart when rubbed between fingers
Where has didymo been found in New York?
Didymo has been confirmed in the following rivers in New York:
Batten Kill and one tributary (Washington County)
Kayderosserras Creek (Saratoga County)
East Branch Delaware River below Pepacton Reservoir (Delaware County)
West Branch Delaware River below Cannonsville Reservoir (Delaware County)
West Branch Delaware River below Delhi to Cannonsville Reservoir (Delaware County)
Mainstem Delaware River (Delaware and Sullivan Counties)
Mouth of Little Delaware River (Delaware County)
Esopus Creek downstream of the Shandaken Portal (Ulster County)
West Branch Croton River (Westchester County)
Please note: these are very popular fishing and water-based recreational rivers. It is very likely that didymo is present in other river systems, but has not been detected yet. Do not assume that rivers not listed above are free of infestation.
Can didymo be eradicated once it becomes established?
There are currently no known methods for controlling or eradicating didymo once it infests a water body.
How is didymo spread?
The primary way for didymo to be spread is by anglers, kayakers, canoeists, tubers, boaters and others engaging in water-based recreation can unknowingly spread didymo. The microscopic algae can cling - unseen - to waders, boots, boats, clothing, lures, hooks, fishing line and other equipment and remain viable for several weeks under even in seemingly dry conditions.

8. Hydrilla or "water thyme" (Hydrilla verticillata)
Hydrilla is a fast growing Asian plant, growing as much as an inch a day. Hydrilla was first discovered in 2008 in a small pond in Orange County and has since been discovered in Broome, Erie, Kings, Monroe, Nassau, Niagara, Suffolk, Tompkins, and Westchester counties.
Hydrilla produces dense mats of vegetation that start to grow along the bottom of lakes and rivers. They grow up to the water's surface where these mats can become several feet thick. The shade out and/or displace native plants that provide food and shelter to native wildlife. They interfere with waterfowl feeding areas and fish spawning sites. Hydrilla disrupts water flow in reservoirs, hampers drainage in irrigation canals, and decreases dissolved oxygen in the water, which results in fish kills. The size and weight of sport fish such as large mouth bass are also reduced in areas infested with hydrilla
Plant fragments can be carried by currents or boats, boat trailers, and fishing gear to new locations.
What can I do?
Inspect and remove plant fragments and mud from boats, trailers, and equipment before and after each use.
Dispose of all debris in trash cans or above the waterline on dry land. Note: tubers and turions can easily be transported in sediment.
Clean and dry your equipment thoroughly before visiting other waterbodies.
Do not dispose of unwanted aquarium plants in waterbodies, ditches, or canals.
Monitor recently acquired aquatic plants because hydrilla tubers can be transported in the attached soil/growing material.
Learn how to identify hydrilla and report infestations to DEC at or (518)