Critter of the Month! - Spiny and Fishhook waterflea

 Spiny and Fishhook Waterflea WATCH

Spiny (Bythotrephes longimanus) and fishhook (Cercopagis pengoi) waterfleas are small predacious crustaceans that threaten aquatic ecosystems and fishing by competing with native fish for food and fouling gear. Both arrived in ships' ballast water from Eurasia. Spiny waterfleas were discovered in Lake Ontario in 1982, then spread to all of the Great Lakes and some inland lakes. Fishhook waterfleas were discovered in Lake Ontario in 1998, then spread to parts of Lake Michigan, Erie, and the Finger Lakes of New York.

Anglers often discover new infestations. Both waterfleas collect in masses on fishing lines and downrigger cables (see photo). These masses can clog the first eyelet of rods, damage a reel's drag system, and prevent fish from being landed. They can spread to inland waters when fishing gear is contaminated with egg-laden females. While females die out of water, under certain conditions they produce eggs that resist dying, remain viable, and can establish a population. Eradicating established infestations is impossible. Your help detecting and reporting new infestations is vital for preventing their spread. 

What you can do:
  • Learn: to recognize these waterfleas on fishing gear.
  • Inspect: and remove aquatic plants and animals, including gelatinous or cotton batting-like material from lines, especially where they meet a swivel, lure or downriggerball connection (plucking like a guitar string helps.)
  • Drain: lake or river water from livewell and bilge before leaving access.
  • Dispose: of unwanted live bait in the trash.
  • Report new sightings - Note exact location; place specimens in a sealed container with rubbing alcohol; and call the Minnesota Sea Great Program in Duluth, (218) 726-8712; or the Minnesota DNR Invasive Species Program in St. Paul, 1-888-MINNDNR or (651) 259-5100
Reminder: Know the rules!
Specimens are needed to confirm sightings, but some jurisdictions prohibit possessions of an invasive waterfleas and other aquatic animals and plants. Contact your loccal natural resources management agency for instructions. Unauthorized introduction of fish, crayfish, or plants into the wild is illegal. Protect your property and your waters. 
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