Sea lamprey in the Delaware River

I had the opportunity to look for spawning sea lamprey in the Delaware River last week as I prepared to sample it this summer.

The image above is not of a lamprey of course, but of a dragonfly emerging into its adult form. This is a Gomphidae (family), and there was a large hatch while I was there. The rocks and nearby vegetation was covered in these guys. Bad news for any insect smaller than they. All dragonflies are accomplished and voracious predators.

Here is a great picture of a large lamprey nest. You can easily see all the cleared areas that the lamprey have prepared and the cleaned stones at the base of the nest. I did not see any adults in the nest when I came. They may have moved on or been scared off by something before I arrived. The nest is about 2-3 feet across.

The video above is of two lamprey preparing to spawn. They move stones and remove sand from the area in which the eggs will be laid. These two were alone, sometimes you can find large numbers of adults all digging nests nearby one another.

All in all a pretty interesting trip. Hopefully more great finds to come this summer in the Delaware!