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Rainbow Smelt

Invasive Species Assignment

Meagan Carvalho

on 16 December 2012

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Transcript of Rainbow Smelt

Rainbow Smelt It is a predatory fish native to the north Atlantic coastal regions of North America. What Is It? They are found in many places in North America including the Great Lakes and many coastal rivers. Where Is It From? (Osmerus mordax) -olive-green on the back, becoming lighter on the sides;
-sides have a purple, pink and blue iridescence, especially when freshly caught
-the belly is silvery
-large mouths with fang-like teeth and a protruding lower jaw
-the tail fin is deeply forked
-spawning males are covered on the head, body and fins with tiny bumps
-smelt in freshwater are darker, becoming almost black on the back. Physical Characteristics They have spread throughout many lakes via introductions and the opening of various canals in eastern Canada and the
US. Introductions to inland lakes of Ontario have resulted in their dispersal further east into Lake Winnipeg and the western coast of Hudson Bay, via the Nelson River. Rainbow smelt invade new waters by moving through connected waters and through human transfer. How Did It Get Here? This species of Smelt will often dine on small invertebrates, zooplankton, Whitefish, sculpins, and are even known to eat other Smelt! Feeding Habits - relatively small, cold-water and oligotrophic lakes.
- Small and Large smelt tend to occupy cool, deeper waters of the lake, except during the spring spawning
season. Habitat The effect that The rainbow smelt has on an ecosystem is that it's eating habits may disrupt food webs and lead to declines of the small animals known as zooplankton that are eaten by other fish. It also has already led to reduced populations of native fish species such as yellow perch, walleye, lake herring, whitefish and lake trout. And they eat the young of other species and may then be eaten by other adult fish, resulting in concentrations of contaminants in native fish that may be a human health risk.
What Effect Does This Invader Have On An Ecosystem?
Life Cycle Smelt eggs are I mm in diameter and take 11 to 29 days to hatch, depending on the temperature. Eggs Young smelt feed on plankton (tiny organisms suspended in the water) and may grow to 5 cm. Young Smelt Older Smelt eat larger invertebrates and other fish. They grow most rapidly in their first year and can tolerate increasing amounts of saltwater as they get older. They prefer temperatures of 6 to 14C and stay close to shore, seeking cover in the mud. Fully Grown Smelt The Rainbow Smelt has invaded many major aquatic systems. Some of the places that it has invaded are as follows ;
- St.Lawrence River
- The Great Lakes
- Lake Simcoe
- Lake Nipissing
-Lake Nipigon
-Many Smaller Inland Lakes
- Hudson Bay Watershed
- Lakes in Northern Western Ontario
- Lake Winnipeg What Part Of The Country Has It Invaded? A few of the things that we can do to stop this invasive species are to stop using rainbow smelt as fishing bait, when cleaning rainbow smelt, be careful not to dump entrails into a lake or river because fertilized rainbow smelt eggs can easily invade new waters, never rinse out a container that has held smelt captured during spawning season into any lake or stream (it may contain fertilized eggs), and to never dump live fish from one body of water into another. What Can We Do? Several things are being done to manage this species. Massive fish removal by over-fishing reduced the rainbow smelt populations in some lakes. Some people are taking a chemical approach to this growing problem, using Rotenone. Rotenone is described as "a slow-acting poison which interferes with the electron-transport system in the mitochondria. It acts as both a contact and stomach poison". While this is effective, it also harms other organisms and is unpopular with the public. Though it is decreasing the number of Smelt in that particular area, it is also harming other species which is not good. This species should continue to be monitored and managed for the benefit of the ecosystem. What Strategies Are Being Used To Control This Species? We have learned that even the smallest thing could lead to a huge outcome! Like how just a simple thing like dumping caught fish back into the water, or dumping your previously used bucket into a lake to get water could lead to the fertilization of smelt eggs and now, face the issue of this species invading many aquatic ecosystems. What Lessons Have We Learned?
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