Thursday, September 9, 2010

Electroshocking for Snakeheads

Potomac tributaries and Potomac river from Pohick bay to Little Hunting Creek on 9/8/2010.

Read my notes below or listen to me discuss each bullet point on itunes

Channa argus 
1 caught, sighted 3-4



Origin:

  • Appear to  have originated in Dogue creek and dispersed from there
  1. Ceremonial dumping 
  2. Food source
  3. Sporting
  4. Pet.
Distribution:
  • 10 miles below colonial beach up Potomac to Great Falls
  • Saline barrier at bay and physical barrier of falls
  • Fish ride fresh water flows down river from floods that spread into saline and they get access to new streams juveniles have tolerance for salinity
  • Can’t determine if in C&O canal due to electric motors not allowed and thus no electro shocking.

Habitat:
  • Breathe air so they can occupy places other fish don’t – shallow, warm waterTucked up against bank in shallow water
  • Hide from birds which will get them when they come up to breathe
  • Under structure (docks, boats) in spring when plants not yet grow
  • Under lilly pads and hydrilla in summer
  • High tide against bank
  • Low tide draws them to edge of plants
  • Not territorial. Tracking has shown preference for a single spot but will move away and return to that same spot.

Reproduction:
  • 80,000 young per year
  • Protect  young.

Feeding:
  • 3 tiers of food based on size. Smaller fish to bigger fish
  • Jaw extends out to engulf prey
  • Can eat prey 1/3 body size
  • Sharp teeth like running finger against grain on blade of grass
  • Teeth angled to hold fish in place.

Size:
  • Up to 15lbs
  • Age determined by otoliths –literally translates to ear bone. Like aging a tree by rings.

Competition with other fish:
  • Based on what I saw, the numbers and sizes of the fish from crappie to largemouth,  I can say they are not eating all the fish in the water as rumored to do so.

Walk on land:
  • Body structure would not allow this
  • Weak pectoral fins made of soft rays would not support fish
  • Could flop around to move but not cross great distance or any physical topography
  • Mucous to protect them while out of water.

Winter:
  • May burrow into mud and remain dormant
  • Surviving winter allows them to live here. Species in Florida could not survive winter here.

Demeanor:
  • Did not appear to be aggressive toward us
  • Some may be more pissed off than others
  • When shocked it was motionless, when awake it wanted to get back to water like any other fish.

Other Fish Species Shocked Up:
  • Carp 
  • Goldfish 
  • Shad (variety) 
  • Eel 
  • Gar 
  • Blue Catfsih 
  • Channel Catfish 
  • Bullhead Catfish 
  • Largemouth Bass 
  • Pumpkinseed 
  • Various Sunfish 
  • White Perch
  • Yellow Perch
  • Black Crappie

Birds:
  • Osprey
  • Bald Eagle
  • Heron
  • Egret
  • Ducks & Geese

John + Flamingo 

 Likely spot to find a snakehead

Electroshocking equipment


 John + reporter

 Nice house!

 Shout out to George

Little Hunting Creek entrance

Please let me launch my yak from your dock

 Note the dense plant population. Very hard to sight and scoop up fish with that much plants.


 Big carp

 Big crappie
  We got one









 Big crayfish. Sans claws.















 
 This fish will still be alive on ice on Saturday.
 Carp beaching itself. Wake helps put fish back in water.




 We missed one in the muck.


 I try scooping up fish. The person closest to the shore had the best shot as the fish were hiding under the weeds.















3 comments:

Rob,

What voltage where they using on the snakehead? Did you notice any fish that did not recover when zapped?

Mike

Mike, I am not sure of the voltage. I did see one floater. It was a huge introduced goldfish with a hole in its side. Could have bee a bird beak puncture. The gulls have learned to follow the boat to eat small stunned fish. A heron or egret may have gotten to it while it was stunned. It was on a small creek that we shocked and returned to a few minutes later. It was floating down stream from the location we had previously shocked.


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