Sea lampreys do not have many known predators, and their most common predator are humans. While sea lampreys in the Great Lakes region are often killed in preservation efforts of native fish, sea lampreys are also trapped in Europe, Asia, and India to be consumed and are even considered a delicacy. Many European countries capture sea lampreys and use them in a variety of dishes.
Known Predators:
Sea lampreys, Petromyzon marinus, belong to a group of fish called Agnathans, which lack a jaw. Although classified in the subphylum Vertebrata, this species lacks vertebrae, and their entire skeleton is cartilaginous. Commonly known for their smooth, scaleless physique and long cylindrical bodies, they are often misidentified as eels. Sea lampreys also lack swim bladders and a lateral line system. Members of this species have a visible eye spot located on each side of their head behind a single nostril and above a set of seven gill openings. Their mouth takes on an oval shape while attached to their host, but once opened it becomes larger than the head and pharynx together. Inside the oval-shaped mouth are numerous rows of large teeth pointing inward. Sea lampreys have two dorsal fins but lack any paired fins. When spawning occurs, males develop a distinct ridge along their back and females develop a pronounced fold of skin behind their vent.
Sea lampreys are the largest and most aggressive species of lamprey, ranging from 15.2 to 30 cm in length as juveniles and 30 to 100 cm in length as adults. Adults can weigh up to 2.5 kg. Besides length, there are several key differences between adult and young sea lampreys. Color is often a good indicator of age; larvae generally are dark, greenish brown with a light grey underbelly, while adults are brownish grey and tend to lighten in color when about to spawn. Another key difference involves the dorsal fins; while separate in young lampreys, the dorsal fins migrate closer together as sea lampreys reach adulthood.
Range mass: 1 to 2.5 kg.
Range length: 15.2 to 30 cm.
Other Physical Features: bilateral symmetry ; polymorphic
Sexual Dimorphism: sexes shaped differently
Sea lampreys die soon after spawning. They can survive up to 5 years in the wild waiting for the opportune time to reproduce. Most lampreys, however, live 1.5 to 5 years in the wild.
Range lifespan
Status: wild: 1.5 to 5 years.
Typical lifespan
Status: wild: 1.5 to 5 years.
Sea lampreys are anadromous, and migration is triggered by changes in water temperature. In general, they prefer shallow coastal areas, though they are found at depths between 0.91 and 4.57 m. Young lampreys are hatched in gravel or rock beds in small, freshwater streams and rivers. After the larval stage, they migrate into saltwater ocean habitats. They return to freshwater to lay their eggs. Sea lampreys thrive in systems where the following are present: 1) waterways lacking obstructions (like dams or waterfalls) with clean sand and gravel areas for spawning; 2) sand beds free of pollutants with a large supply of organic matter for their developing young; and 3) large waterways with a plentiful supply of fish to serve as hosts for their fully developed offspring.
Range depth: 0.91 to 4.57 m.
Habitat Regions: saltwater or marine ; freshwater
Aquatic Biomes: lakes and ponds; rivers and streams; coastal
Sea lampreys are native to the Atlantic Ocean. Between the months of March and October, they can be found along the coast of the United States as far north as Massachusetts and as far south as South Carolina. In October, North American lampreys migrate south along the Atlantic coast to warmer climates, some travelling as far south as Florida. Sea lampreys can also be found along the Atlantic coast of Europe as far north as Norway and ranging as far south as the Mediterranean. In October, they can travel as far south as Africa and to parts of the Indian coast. Sea lampreys have also been introduced to the Great Lakes region of the United States many times over within the past 200 years. Reports of this species in Lake Ontario date back to the early 1800s. Great Lake sea lampreys must first travel through the Gulf of St. Lawrence in order to gain access to the Atlantic coastal region.
Biogeographic Regions: nearctic (Introduced , Native ); palearctic (Native ); oriental (Native ); atlantic ocean (Introduced , Native ); mediterranean sea (Introduced , Native )
Newly hatched larval sea lampreys are freshwater filter-feeders that consume detritus, algae, and other organic material found at river bottoms. Once in a saline environment (or in the Great Lakes), sea lampreys develop parasitic abilities, attach themselves to a fish and ingest their blood and skin. Sea lampreys ultimately breaks down the fish while the fish is still alive. This species is capable of attaching itself to a variety of species of fish and does not seem to have a preference of host species. Once sea lampreys reach sexual maturity, they no longer feed.
Animal Foods: fish; blood; body fluids; carrion
Plant Foods: algae
Other Foods: detritus
Foraging Behavior: filter-feeding
Primary Diet: carnivore (Piscivore , Sanguivore , Eats body fluids); herbivore (Algivore); omnivore ; detritivore
Communication patterns of sea lampreys are not well known. It is thought male sea lampreys emit a pheromone composed of bile acids that alerts ovulating females to their presence. This signal may also be related to mating preferences and may be sent over large distances.
Other Communication Modes: pheromones
Perception Channels: visual ; chemical
Sea lampreys are not protected. Indeed, as invasive species, efforts are in place to eradicate them from the Great Lakes region. Both federal and state governments have created programs to manage populations of and educate the community about this invasive, harmful species. Barriers and traps are set in the waterways to capture adult sea lampreys before they reproduce. Lampricides are also added to prime habitat of sea lampreys. These treatments specifically target lampreys and are designed not to harm other species. Each program has been tested for several years and has proven an effective control of sea lampreys.
US Federal List: no special status
CITES: no special status
State of Michigan List: no special status
IUCN Red List of Threatened Species: least concern
There are four stages in the life cycle of sea lampreys, which usually spans 18 months but can last as long as 5 years. The first of these stages is the spawning phase, which occurs during spring and early summer. From April to June, sea lampreys search freshwater rivers and streams, seeking an ideal location in which to construct a nest and lay their eggs. Once the area is selected, male sea lampreys construct a nest, often moving rocks to create a large indenture or depression in the river or lake bed. A female then lays 30,000 to 100,000 eggs, which the male externally fertilizes. Both male and female adult sea lampreys float away and die soon after spawning. Unique to this phase is the disintegration of the digestive system; adult sea lampreys cannot feed while spawning. During the second phase, fertilized eggs settle into the sand or gravel and begin to grow. Within a few weeks, the eggs hatch and the larvae burrow further into the sand or gravel. Larvae filter-feed on algae and other aquatic organic matter. This larval phase can last for more than three years. In the third phase, known as transformation, larvae metamorphose into adult sea lampreys. During this phase sea lampreys develop a mouth, teeth and eyes. They also migrate to larger bodies of water, such as oceans or freshwater systems like the Great Lakes. Sea lampreys remain in this habitat for 12 to 18 months as a mature adult and begin to feed, attaching themselves to fish. This is known as the parasitic phase, during which sexual reproductive organs develop.
Development - Life Cycle: metamorphosis ; indeterminate growth
Because of their over-aggressive behavior and generalist diet, sea lampreys parasitize many species of fish, contributing to the severe decline of commercial fishing industries, including those on the Atlantic coast of North America and in the Great Lakes region. Each sea lamprey kills more than 18.2 kg of fish each year. This species has parasitized many species of native fish in the Great Lakes region since the early 1800s, leading to the collapse of the Great Lakes commercial fishing industry and costing it millions of dollars. Population declines of native fish in the region have also negatively impacted sport fishing and tourism. In one case, a sea lamprey bit a human, though this is thought to have been accidental.
Sea lampreys are considered a delicacy in many foreign countries like Asia and India and are harvested for food.
Positive Impacts: food
Parasitic sea lampreys have a detrimental effect on fish within their ecosystem. Specifically, sea lampreys feed on salmon, lake trout, rainbow trout, whitefish, chubs, burbot, walleye, and some catfish. Fish populations as as well as those industries that depend on fish are declining. Sea lampreys have no known predators except humans. In the Great Lakes region, a small percentage of sea lampreys carried cestode parasites or roundworms during some portion of its life. Of these parasites, only roundworms caused severe damage to their lamprey hosts.
Ecosystem Impact: parasite
Species Used as Host:
Commensal/Parasitic Species:
Little is known about the mating systems of sea lampreys. It is thought that male sea lampreys emit a pheromone composed of bile acids that alerts ovulating females to their presence. This signal may also be related to mating preferences and may be sent over large distances. Male sea lampreys selectively dig holes into river or stream bottoms and fertilize eggs once the female has laid them. This external fertilization allows multiple males to fertilize eggs.
Mating System: polygynous
From April to June, female sea lampreys lay between 30,000 and 100,000 eggs. These eggs are fertilized externally by males. Fertilized eggs hatch in 3 to 8 weeks. Larvae spend 1 to 3 years filter-feeding and do not associate with other sea lampreys. By 3 to 5 years of age, sea lampreys reach sexual maturity.
Breeding interval: Sea lampreys breed once at the end of their lifetime.
Breeding season: Sea lampreys breed between April and June.
Range number of offspring: 30,000 to 100,000.
Range gestation period: 3 to 8 weeks.
Range age at sexual or reproductive maturity (female): 3 to 5 years.
Range age at sexual or reproductive maturity (male): 3 to 5 years.
Key Reproductive Features: seasonal breeding ; sexual ; fertilization (External ); oviparous
Male sea lampreys selectively locate a nesting area. Sea lampreys do not allocate energy toward parental investment after laying and fertilizing eggs, as both male and female sea lampreys die shortly after spawning.
Parental Investment: no parental involvement; pre-fertilization (Provisioning, Protecting: Male, Female); pre-hatching/birth
The sea lamprey (Petromyzon marinus) is a parasitic lamprey native to the Northern Hemisphere. It is sometimes referred to as the "vampire fish".
The sea lamprey has an eel-like body without paired fins. Its mouth is jawless, round and sucker-like, and as wide or wider than the head; sharp teeth are arranged in many concentric circular rows. There are seven branchial or gill-like openings behind the eye. Sea lampreys are olive or brown-yellow on the dorsal and lateral part of the body, with some black marblings, with lighter coloration on the belly. Adults can reach a length of up to 120 cm (47 in) and a body weight up to 2.3 kg (5.1 lb).[4]
The etymology of the genus name Petromyzon is from petro- "stone" and myzon "sucking"; marinus is Latin for "of the sea".
The species is found in the northern and western Atlantic Ocean along the shores of Europe and North America, in the western Mediterranean Sea, the Black Sea, and as an invasive species in the shores of the Great Lakes.[1] They have been found at depths up to 4000 meters and can tolerate temperatures of 1–20 °C (34–68 °F).[4]
In North America, they are native to the Connecticut River basin in the United States.[5] The largest European populations of sea lampreys are located throughout the southwestern areas of Europe (north-central Portugal, north-northwest of Spain, and west–southwest of France).[6] These countries also support the main fisheries of the species.[7]
Sea lampreys are anadromous; from their lake or sea habitats, they migrate up rivers to spawn. Females deposit a large number of eggs in nests made by males in the substrate of streams with moderately strong current. Spawning is followed by the death of the adults. Larvae burrow in the sand and silt bottom in quiet water downstream from spawning areas and filter-feed on plankton and detritus.[1]
After several years in freshwater habitats, the larvae undergo a metamorphosis that allows young, post-metamorphic lampreys to migrate to the sea or lakes, and start the adult hematophagous method of feeding.[8] Some individuals start hematophagous feeding in the river before migrating to the sea,[9] where sea lampreys prey on a wide variety of fish.[10]
The lamprey uses its suction cup-like mouth to attach itself to the skin of a fish and rasps away tissue with its sharp, probing tongue and keratinized teeth. A fluid produced in the lamprey's mouth, called lamphredin,[11] prevents the victim's blood from clotting. Victims typically die from excessive blood loss or infection. After one year of hematophagous feeding, lampreys return to the river to spawn and die, a year and a half after the completion of metamorphosis.[12]
Lampreys are considered a delicacy in some parts of Europe, and are seasonally available in France, Spain, and Portugal. They are served pickled in Finland.[13]
Due to its lifecycle that switches between fresh and salt water, the sea lamprey is adapted to tolerate a wide range of salinities. Cell membranes on the surface of the gills are major contributors to ionoregulation. Changes in membrane composition influence the movement of different ions across the membrane, changing amounts of components to change the membranes' environment.
As the larvae (called ammocoetes) move towards the oceans, the ratio between saturated fatty acids (SFA) and polyunsaturated fatty acids (PUFA) in the gills shifts towards higher amounts of SFA, as they affect the fluidity of the membrane, and higher levels of SFA lead to a decrease in permeability compared to PUFA.[14] Lamprey ammocoetes have a relatively narrow range of salinity tolerance, but become better able to withstand wider ranges of salinity concentrations as they reach later stages of life. Tight regulation of Na/K-ATPase and an overall decrease in expression of H-ATPase assists in regulating the lamprey's internal fluid and ion balance as it moves to areas of higher salinity.[15]
Lampreys also maintain acid-base homeostasis. When introduced to higher levels of acids, they are able to excrete excess acids at higher rates than most other saltwater fishes, and in much shorter times, with the majority of the transfer of ions occurring at the gill surface.[16]
Sea lampreys parasitize other fishes for their diet, including elasmobranchs such as sharks and rays, which have naturally high levels of urea in their blood. Urea is toxic to most fishes in high concentrations, and is usually excreted immediately. Lampreys are able to tolerate much higher concentrations than most other fish and excrete it at extremely high rates, obtained from ingested blood. Trimethylamine oxides present in ingested elasmobranch blood aid in counteracting the detrimental effects of high urea concentration in the lamprey's bloodstream as it feeds.[17]
Two presumptive apolipoprotein B mRNA editing enzyme, catalytic polypeptide-like (APOBEC)s expressed in lymphocytes—CDA1 and CDA2—have been discovered in P. marinus.[18]
The genome of Petromyzon marinus was sequenced in 2013.[19] This sequencing effort revealed that the lamprey has unusual guanine-cytosine content and amino acid usage patterns compared to other vertebrates. The full sequence and annotation of the lamprey genome is available on the Ensembl genome browser.
The lamprey genome may serve as a model for developmental biology and evolution studies involving transposition of repetitive sequences. The lamprey genome undergoes drastic rearrangements during early embryogenesis in which about 20% of the germline DNA from somatic tissues is shed. The genome is highly repetitive. About 35% of the current genome assembly is composed of repetitive elements with high sequence identity.[19] Northern lampreys have the highest number of chromosomes (164–174) among vertebrates.[20]
Two genes important to immune function—CDA1 and CDA2—were first discovered in P. marinus and then found to be conserved across lampreys. See §Immunology above.[18]
Sea lampreys are considered a pest in the Great Lakes region. The species is native to the inland Finger Lakes and Lake Champlain in New York and Vermont. Whether it is native to Lake Ontario, where it was first noticed in the 1830s, or whether it was introduced through the Erie Canal which opened in 1825 is not clear.[21] Improvements to the Welland Canal in 1919 are thought to have allowed its spread from Lake Ontario to Lake Erie, and while it was never abundant in either lake, it soon spread to Lake Michigan, Lake Huron, and Lake Superior, where it decimated indigenous fish populations in the 1930s and 1940s.[22]
In its original habitats, the sea lamprey coevolved with its hosts, and those hosts evolved a measure of resistance to the sea lampreys. However, in the Great Lakes, the sea lamprey attacks native fish such as lake trout, lake whitefish, chub, and lake herring, which historically did not face sea lampreys. Elimination of these predators allowed the alewife, another invasive species, to explode in population, with adverse effects on many native fish species.
The lake trout plays a vital role in the Lake Superior ecosystem. The lake trout has traditionally been considered an apex predator, which means that it has no predators. The sea lamprey is an aggressive predator by nature, which gives it a competitive advantage in a lake system where it has no predators and its prey lacks defenses against it. The sea lamprey played a large role in the destruction of the Lake Superior trout population. Lamprey introduction along with poor, unsustainable fishing practices caused the lake trout populations to decline drastically. The relationship between predators and prey in the Great Lakes ecosystem then became unbalanced.[23] Each individual sea lamprey has the potential of killing 40 pounds of fish through its 12–18 month feeding period.[24]
Control efforts, including electric current and chemical lampricides[25] have met with varied success. The control programs are carried out under the Great Lakes Fishery Commission, a joint Canada–U.S. body, specifically by the agents of the Fisheries and Oceans Canada and the United States Fish and Wildlife Service.
Genetic researchers have mapped the sea lamprey's genome in the hope of finding out more about evolution; scientists trying to eliminate the Great Lakes problem are coordinating with these genetic scientists, hoping to find out more about its immune system and fitting it into its place in the phylogenetic tree.
Researchers from Michigan State University have teamed up with others from the Universities of Minnesota, Guelph, and Wisconsin, and others in a research effort into newly synthesized pheromones. These are believed to have independent influences on the sea lamprey behavior. One group of pheromones serves a migratory function in that when they are made by larvae, they are thought to lure maturing adults into streams with suitable spawning habitat. Sex pheromones emitted from males are capable of luring females long distances to specific locations. These pheromones are both several different compounds thought to elicit different behaviors that collectively influence the lampreys to exhibit migratory or spawning behaviors. Scientists are trying to characterize the function of each pheromone, and each part of the molecules, to determine if they can be used in a targeted effort at environmentally friendly lamprey control. However, as of 2017, the most effective control measures still involve the application of (3-trifluoromethyl-4-nitrophenol), or TFM, a selective pesticide, into rivers.[26] As of 2018 no lampricide resistance has been detected in the Great Lakes. Further research and combined use of multiple control methods are needed to forestall future development of resistance.[25]
Another technique used in the prevention of lamprey population growth is the use of barriers in major reproduction streams of high value to the lamprey. The purpose of the barriers is to block their upstream migration to reduce reproduction. The issue with these barriers is that other aquatic species are also inhibited by this barrier. Fish that use tributaries are impeded from traveling upstream to spawn. To account for this, barriers have been altered and designed to allow the passage of most fish species, but still impede others.[27][28]
The intent of lamprey control programs is a safer habitat and a healthier population growth for vulnerable native fish species such as lake trout. The Connecticut Department of Energy and Environmental Protection (DEEP) has taken a different path to this same goal by introducing sea lampreys to freshwater rivers and lakes of the Connecticut River watershed, and providing easier access around dams and other barriers for the lampreys to reach spawning sites high upstream.[29] After preying on larger fish at sea, the adult lampreys migrate up the rivers to spawn, whereupon they quickly die of natural causes and decompose, thus providing a food source for the native freshwater fish species.
{{cite book}}: CS1 maint: multiple names: authors list (link) {{cite journal}}: CS1 maint: multiple names: authors list (link) {{cite journal}}: CS1 maint: multiple names: authors list (link) The sea lamprey (Petromyzon marinus) is a parasitic lamprey native to the Northern Hemisphere. It is sometimes referred to as the "vampire fish".
