Petromyzon marinus
Biology
Sea Lamprey have one of the most complex life cycles of any of Maine’s anadromous (migrating from sea water to fresh water to spawn) fishes. They are native to Maine and should not be confused with the sea lamprey of the Great Lakes. Although they are the same species their ecological impacts are quite different. Anadromous Sea Lamprey are found all around the North Atlantic, as far south as the Chesapeake in North America and Spain in Europe.
In their native range, lamprey are considered ‘ecosystem engineers’ and play an important role in conditioning streams and rivers for other fish that spawn after them. Adult lamprey, 2-3 ft in length, migrate upstream from the ocean in May and early June. Lamprey spawn in the same habitat as Atlantic salmon, but 6 months earlier. Males do most of the nest making by picking up stones and gravel to excavate a depression. Females will choose a nest by grabbing a stone just above the nest and holding on, signaling the male to suction onto her. They release eggs and milt (sperm) that fertilizes the eggs, which are subsequently stuck in the depression. The adults die in the stream after spawning, fertilizing the habitats where their offspring will develop with marine derived nutrients, carbon and nitrogen accumulated in the lamprey bodies from a year at sea.
The eggs take up to a month to hatch. The resulting larvae are called Ammocoetes, and they look like hooded worms. They burrow into soft sediments and filter feed on detritus, bacteria and plankton for up to seven years. Once they are large enough, Ammocoetes begin a metamorphosis (body change). They develop fins, a swim bladder and the mouth disk, horny teeth and rasping tongue that gives them their nickname, “vampire fish”. While migrating and at sea, lamprey attach to host fish, holding on with their unique mouths and then opening a wound through which they consume the hosts blood for nutrients. The ocean phase lasts for 12 – 18 moths. Once they return to freshwater lamprey cease feeding and will migrate, spawn and die as the end of their semelparous (spawning once) life history.
Status and Management
DMR is responsible for harvest regulations around Sea Lamprey fished in tidal and coastal waters. The DMR commissioner issues special permits for “Lamprey eel”, to maintain regulatory separation between Sea Lamprey harvest and harvest of the American eel. Lamprey are usually caught in trap nets with special provisions similar to those for American Eel:
-
No net can cover >2/3 of the stream width at low tide,
-
Nets cannot be longer than 30 ft,
-
Mesh size must be between 1/8 in and 1 in,
-
Gear must be tended every 24 hrs to reduce bycatch.
The primary use for lamprey harvested in Maine is for the biological specimen market. Lamprey are preserved in formaldehyde or frozen and sent to universities, high schools and biological labs.
DID YOU KNOW
Lamprey are an ancient fish. They have not changed much from fossils found 340 million years ago.
The sea lamprey’s scientific name, Petromyzon marinus, means “sucker of stone from the sea”, referring to their conspicuous nest building.
Sea lamprey are a delicacy in Spain, Portugal, France and other western European countries, where the most active commercial fisheries are located.