Sea Lamprey CER

The Sea Lamprey definitely caused a decline in the trout population. The text in our science binders states that the trout is the sea lamprey’s prey. We also looked at a chart of the populations of sea lamprey and trout in the great lakes. While the trout went steadily downwards (from 200 to nearly 0), the sea lamprey dramatically spiked up (from 0 to 300). Also, on the great lakes food web that our class created, the sea lamprey was eating the trout. There was also nothing eating the sea lamprey. This means that when the sea lamprey invaded the great lakes they just started eating everything else (including the trout) and didn’t get eaten themselves because since they were at the top of the food chain there were no predators above them. Without predators, they ate a lot of trout.

According to a fisherman, when farmers started catching fish in the 1960s, the fish all had a hole in the side of them with blood coming out. The way the sea lamprey gets food is by attaching to the side of a fish and sucking out the blood. They use their teeth to grab on to the fish and make a hole to suck the blood out of. This would line up perfectly with what the farmers would say they’re catching. This proves that the sea lamprey are sucking blood from the trout and killing them that way so the trout population decreased with a new deathly predator.

Another reason the sea lamprey caused a decline in the trout population is that when sea lamprey lay eggs, they lay about 80,000. When trout lay eggs, they lay about 800. If the trout laid more eggs than the sea lamprey, there is a possibility the sea lamprey’s population would not be large enough to wipe out the trout, but because the sea lamprey lay more eggs, their population would very quickly outnumber the trout’s. Therefore, the trout are unable to outnumber the sea lamprey and make it so the sea lamprey can’t eat all of the trout.

All of this evidence proves that the sea lamprey caused a decline in the trout population.