Fish hook flea was introduced into the Great Lakes in the 1980's. Most likely
in ballast water taken up in the Caspian Sea. The flea is about 1 cm long,
with a long spiney tail with a unique loop at the end. The tail comprises about
80% of the flea's length. These long tails become entangled on fishing lines,
and on one another, creating clumps that look and feel like wet cotton, with
tiny black dots that are the single eyes of each individual. The flea reproduces
numerous times in a single season. They feed on zooplankton. Large populations
could cause a decline of native zooplankton species, impacting juvenile and small
fish that feed on zooplankton, and larger fish that feed on these smaller species.
In the areas where they have become established, they have had a negative impact
on recreational anglers and could have an impact on commercial fishers if they
foul their nets.