Image from Animal
Diversity Web
Classification
Kingdom: Amimalia
Phylum: Chordata
Subphylum: Vertebrata
Class: Cephalaspidomorphi
Subclass: Cephalaspidomorpha
Order: Petromyzotiformes
Family: Petromyzontidae
Genus: Petromyzon
Species: Petromyzon marinus
Phenotypic Facts
Length:
12-
20 inches
Weight: 8- 13 ounces
Coloring: grey-blue black, metallic violet on the sides, shading silver-white
on belly
Image
from Animal
Diversity Web
Table of Contents
The Affects of Predation by Sea Lamprey
Introduction
Image from Gimp Savvy
Petromyzon marinus, commonly known as sea lamprey, are a primitive eel-like species native to the coast lines of the Atlantic Ocean. Their bodies are comprised of soft cartilage. They have smooth scaleless skin and lack bones, paired fins, a lateral line, a swim bladder, and a jaw (Bowen, 2006). It has recently been shown that this ancient animal is an ancestor of the first vertebrates (University of Florida, 2006). Another characteristic of adult lamprey is their sucking oral mechanism. This sucker allows them to latch on to a prey item much bigger than themselves. Their horn-shapped teeth and rasping tongue cause a wound through which the lamprey sucks the blood of it’s prey. During this parasitic adult stage, a lamprey consumes an average of 40 pounds of life (Bowen, 2006). When in their natural habitat, lamprey populations remain manageable. However, this invasive species has caused a huge disruption in the Great Lakes ecosystem where it’s parasitism has resulted in a crash of the population of lake trout. The ongoing project of controlling the lamprey population in the Great Lakes has proven to be quite a challenge.
Development and Reproduction
Having an in-depth understanding of the sea lamprey life cycle is crucial to the effective control of their population as well as the populations of their prey. Sea Lamprey go through three critical stages in their development; the sedentary stage, the free swimming stage, and the reproductive stage.
Image from Gimp
Savvy
The Reproductive Stage
The reproductive stage takes place primarily during the months of April through July, and is defined by the spawning of the sexually mature adult sea lamprey. The adult lamprey travel from the fresh water lakes to tributary streams which serve as their breeding ground. This migration is thought to be triggered by water temperature. In order for successful reproduction, the water temperature must be between 15.6 and 21.2 degrees Celsius (18 degrees being optimal). The male individuals construct a horseshoe shaped nest to which the female is drawn. The female then attaches to a nearby rock with her sucking mouth and allows the male to coil himself around her. This coiling puts their reproductive structures into contact and allows for fertilization to take place. A spawning female produces an average of 60, 000 eggs, 14% of which are deposited into the nest. Of those deposited, 90% survive to hatch into the larval stage. Once the adult lamprey have spawned, they die within days. Those lamprey unsuccessful in mating also die, as they suffer from the deterioration of their internal structure (Baggio).
The Sedentary Stage
The eggs deposited into the nest hatch into worm like larvae, called ammocoetes, which are carried with the waters current downstream. There they burrow into the stream bed where they will remain for 3-10 years (Lyons, 2006)! During this time they act as filter feeders. Positioning their heads toward the current, they filter the ciliates and diatoms from the passing water (Baggio).
Free Swimming Stage
Once reaching a certain length, the ammocoete (larval lamprey) will emerge from their burrow and undergo a metamorphosis. This takes place between the months of July and September. Changes and Developments that take place during this metamorphic period include:
- the development of functional eyes
- the development of the characteristic sucking mouth parts including horn shaped teeth and a grasping tongue
- a change in color from dull brown to a silvery blue
Once the juvenile lamprey have completed the metamorphosis, they spend 14-15 months in a parasitic adult stage where they further their sexual maturation (Baggio). During this parasitic stage, the adult sea lamprey will consume an average of 40 pounds of life (Bowen, 2006).
Feeding
Although filter feeders while in the larval stage, adult sea lampreys are external parasites that feed on large fish. While not picky eaters, the sea lamprey present in the Great Lakes seem to favor the Great Lakes Lake Trout. During the animals adult life, it consume an average of 40 pounds of life (Bowen, 2006). The characteristic sucking mouth parts of the lamprey allow it to attach itself to the body of a large trout. It’s horn shaped teeth surrounding the mouth opening clamp onto their prey, keeping them from being shaken off (Lyons, 2006). Once attached, the lamprey uses it’s tongue to rasp a hole in the flesh of its prey through which it sucks it’s blood. The saliva of the lamprey contains an anticoagulant that can keep the wound open and the blood flowing for weeks (Downs, White, and Wittman, 1998).
image from Natural History of Minnesota Fishes
The Affects of Predation by Sea Lamprey
Sea Lampreys are native to the coast lines of the Atlantic Ocean, however they made their way to Lake Ontario in the 1830's via canals constructed to facilitate commerce. In 1919, the improvements made to the Wellington Canal allowed Lampreys to move from Lake Ontario, into all of the Great Lakes.
Beginning in the 1950's and 60's, Sea Lamprey became a huge problem in the the North American Great Lakes. The Great Lakes Lake Trout was pushed toward the brink of extinction due to predation by the Sea Lamprey. New methods of population control have been tested and instigated in the lakes in an effort to regenerate the Lake Trout.
In the 1940's the Lake Trout population began a steady and steep decline. In turn, the decrease of Lake Trout through the entire Great Lake ecosystem out of balance. The populations of the alien species of smelt and alewives flourished due to the decline of their key predator, the lake trout. Not only did these two species crowd to extinction many native species, their deteriorating carcases created such a stench as to deter from tourism.
Image from great-lakes.net
Image created by April Bowen
Methods of Population Control
Once the devastating affects of sea lamprey feeding began to show themselves, the effort to control their population began. A combination of four different methods has lead to a decrease in the lamprey population over the past fifty years (Bowen, 2006; Lyons, 2006).
Lampricide- Currently, the use of a chemical lampride (TFM) is the primary method being used to control the Great Lakes lamprey population. TFM is registered with both the Environmental Protection Agency and Health Canada. The chemical is put into the streams in which lamprey reproduce to kill lamprey larvae. Although costly, this method has proven to be very successful (Bowen, 2006; Lyons, 2006).
Barriers- Barriers have been placed at the at the openings of the tributary streams into the lakes. These barriers inhibit the travel of the adult lamprey to the streams in which they spawn. The barriers cause little disruption to other species and can be deflated during the majority of the year when the lamprey are not looking to reproduce (Bowen, 2006).
The Sterile-Male-Release-Technique- Male lamprey are caught, sterilized, and released back into the population. If successful in its search for a mate, the sterile males produce sterile eggs, thus reducing the lamprey population (Bowen, 2006).
Trapping- Trapping lamprey is used in association with the use of barriers (Bowen, 2006).
Author: April
L. Bowen
Creation/revision date: March 28, 2006
Baggio, Anna. Date unknown. Sea lamprey. Hamilton Harbour. www.science.mcmaster.ca/Biology/Harbour/SPECIES/SEALAMP/TITLE.HTM. March 26, 2006.
Bowen, Debbie. January 23, 2006. Sea lamprey: the battle continues. Minnesota sea grant. http://www.seagrant.umn.edu/exotics/lamprey.html. March 26, 2006.
Downs, W. Wilard, L. White, E.A. Wittman. 1998. Fish of the Great Lakes; Wisconsin sea grant. www.seagrant.wisc.edu/greatlakesfish/sealamprey.html. March 1, 2006.
Fetteroff, Carlos. Date unknown. Sea lamprey in the Great Lakes. Great Lakes Fishery Commission.
http:// biology.usgs.gov/stt/SNT/noframe/gl129.htm. March 26, 2006.
Kahl, Robert. Date unknown. Sea lamprey managment past, present, and future. U.S. Fish & Wildlife Service. http://www.fws.gov/midwest/marquette/slm2.htmlhttp://
www.fws.gov/midwest/marquette/slm2.html.
March 26, 2006.
Lyons, Larry. February 15, 2006. The Great Lakes lamprey then and now. Edwardsburg Argus Online Edition. www.edwardsburgargus.com/articles/2006/02/16/sports/vasports5.txt.
March 1, 2006.
Manninen, Christine. January 4, 2006. Sea lamprey in the Great Lakes region.
http://www.great-lakes.net/envt/flora-fauna/invasive/lamprey.html. March 1, 2006.
Myers, P., R. Espinosa, C.S. Parr, T. Jones, G.S. Hammond, and T.A. Dewey.
2006. The animal diversity web (online).http://animaldiversity.org. March 1, 2006.
The University of Florida. February 26, 2006. Scientists reveal ancient origin of vertebrate skeleton in unlovable lamprey. Science Daily.
http://www.sciencedaily.com/releases/2006/02/060223082831.htm.
March 26, 2006.
The University of Wisconsin Sea Grant Institute. February 2, 2002. Sea lamprey. http://www.seagrant.wisc.edu/greatlakesfish/fsealamprey1.html. March 1, 2006.