EPISODE 305: SEA LAMPREYS: LIFE AND DEATH IN THE GREATEST FISHBOWL ON EARTH

alan skeoch

April 2021

( series titled LIFE  AND DEATH IN THE GREATEST FISH BOWL ON EARTH: THE GREAT LAKES)

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 Sea Lampreys

The first sea Lamprey was found in Lake Ontario in 1835 perhaps  using the new Erie Canal as an access route.

It is suspected that these early sea Lampreys took a short cut north to Lake Ontario first and much later

used the Welland Canal  to get access to the upper Great Lakes.  

 There are four kinds of lampreys but

the sea lamprey was the most  threatening to the Great Lakes fishery because it adapted to fresh water life. And

 found the lake trout easy prey….Slow moving deep  down in Lake Ontario…Fat. Lots of blood…

Easy to grab..  Just swim up beside then use the barbs on their velcro like mouths to hook

a lake trout anywhere and begin sucking the life blood out of them.   One sea lamprey can eat forty pounds

of fish (not just lake trout) 

Since the sea lamprey found life in the Great Lakes abundant with easy prey it did not return to the Atlantic 

ocean as the creature may have planned when it first gained  access.  The  clean, clear, fast flowing rivers

 were ideal  for sea lamprey spawning.   One female sea lamprey produces

up to 100,000 baby lampreys.   It did not take long for the sea lampreys population to overwhelm

the natural fish cycles in the Great Lakes.  By 1960 the top predator, the Lake Trout, that served

the function of keeping the fish population in balance was nearly extinct. 

• Lake Ontario, 1835
• Lake Erie, 1921

• Lake Huron, 1932
• Lake Michigan, 1936
• Lake Superior, 1938

.

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SEA LAMPREYS

SOME FACTS

Sea Lampreys are parasites that feed  by sucking the blood  of host fish like trout, salmon and any others they can sidle up to..  

They are ugly and that is putting it mildly. Adult sea lampreys have an eel like body with dark olive or brown yellowish colouring with

a lighter coloured belly.  Most remarkable and frightening are their heads which are dominated by a round mouth with teeth arranged

in concentric circles and in the centre an opening to the body.   They can grow up  to 1.2 metres in length and weigh 2.5 kg.

Adult sea  Lampreys live in the saltwater seas of the Northern Hemisphere (North Atlantic, Mediterranean, Black seas)  but lays its eggs in freshwater streams with fast currents

where the larvae lay burrowed in the sand  for many years feeding on planktons and detritus.  After several years the larvae suddenly

metamorphize into young adults and historically they head for the sea.  But some adjusted to life in freshwater like Lake Ontario.

  Their life  cycle lasts 5 to 8 years from egg to adult.  Adult sea lampreys live from12 to 20 months sucking

the blood  out of whatever host fish they can find.  The barbed mouth grabs  hold, then a ras-like tongue looses  fish scales to get to the fish flesh and

to suck the fish blood killing  the fish in most cases.  The sea lamprey mouth injects a chemical that prevents the host fish from clotting

its blood.

One sea lamprey moving from host to host can kill 40 pounds of fish every year.

One female sea lamprey can lay 100,00 eggs.

BY 1960 over 85% of fish caught in the Great Lakes had lamprey scars.

Sea Lampreys are not natural natives of the Great Lakes.  How they got here is unclear  Some sources say they came up the Erie Canal

in 1835 .. partway … then decided they liked the cold fast moving rivers feeding  into Lake Ontario where they settled.  Still another

source believes these lampreys have been in Lake  Champlain for 10,000 years.  How they got into the upper Great Lakes may have happened 

In 1929 when the Welland Canal  was  improved for shipping and also for the sea Lampreys.   All sources agree that the

sea lamprey destroyed  the commerce  rising industry  between  1940 and 1950.  Why such a sudden population explosion?

A lot of guesswork and scientific exploration has not completed solved thus sudden devastation.   What is known for sure is

that the sea lampreys had a devastating effect on the Lake Trout population.  As soon as that happened other problems followed.

Life under water is not pleasant.. Big fish eat little fish.  Strange that no fish developed a taste for adult lampreys.

Killing the sea lamprey spawning adults has been achieved by use  of a chemical lampricide, TFN, to kill the larvae.  Also electricity

has been used to prevent adults  lampreys from getting access to their spawning grounds.  Sterilization of males is also used.

Their numbers have been reduced but not extinguished.   Port Credit fisherman, Andrew Skeoch, has found the occasional

ses lamprey attached to coho and chinook salmon.   He practices ‘catch and release’ sport fishing. That is never done with

any lamprey…they  are killed.

Perhaps the most unusual change in the sea lamprey life cycle was the  total adjustment of life in fresh water.  The  Great Lakes

were the ‘golden marine city’  where food was plentiful and clear fast moving streams with gravel and sand bottoms made spawning phenomenally

successful.  One female can lay 100,000 eggs.  Some larvae get eaten by other creatures but one sampled river in the upper Great 

Lakes trapped  22,000 sea lampreys  as they headed downstream and changed  into vicious predators.

One of the strangest adult changes is that they begin to breathe through 7 holes partway down their body and their eyes become

sinister looking just above their suddenly enlarged and spike filled lethal mouths. Vampires of the Great Lakes.

alan  skeoch

Threats to Great Lakes   1) Overfising  2) Sea Lampreys  3) Alewife (COMING NET EPISODE)