Wednesday, December 7, 2011

A True Story About the Collapse of a Fishery and It's Recovery : Part 2

*Disclaimer* What follows is my own personal experience in a sad situation. I have talked to local biologists about this , but I may not get all the facts absolutely correct. I hope my personal experiences shed light on the severity of a fish kill that hit very close to home for me and serve as a cautionary tale to those who don't follow rules intended to protect our waters from invasive species. Several factors could align and almost any body of water could experience something very similar or even worse.

You may want to read Part One first.

Part Two : A Two Headed Monster

Courtesy of arkansasstripers.com
The Fall of 2002 began like any other year here on Smith Mountain Lake. We fished. We caught fish , but as the month of October wore on , we began to notice something wasn't right. Some fish had sores in their mouths. Others had worms. Or more precisely , parasitic copepod ( Actheres ) infestations.

How they ended up in Smith Mountain Lake is and will remain a mystery. One theory holds that they occur naturally in the water and only started to attack Stripers as the fish became stressed. Another tells a different tale that begins with the parasites being introduced on the upper end of the Roanoke River arm of the lake and spreading throughout the system from there. I won't go into my opinions on the matter. For my purpose here we just need to know that the copepods are here to stay.

Like any parasite , copepods are opportunistic. They will attach themselves onto just about any species of fish without hesitation. Generally they are found in the fish's mouth and gills. A study done in Europe indicated that a heavily infested fish had , on average , 7 copepods in its mouth/gills. I wish our fish had been "heavily infested". One fish taken from the lake in late 2002 had up to 400 copepods in its mouth!

Why so many? Several factors worked in unison to allow the Striped Bass population to become so heavily infested with copepods. While Stripers are a hardy fish that thrives in both salt and freshwater , forcing them to live in freshwater takes it's toll. They are far more susceptible to stress from warmer water temperatures than their saltwater brethren. This certainly played a roll in the infestation , because the summer of 2002 was hot and dry across much of the nation , including Virginia. Little rain combined with intense heat allowed SML to warm rapidly and stay that way , increasing the likelihood of stress in the Striped Bass population.

Another factor to consider is that our SML Stripers apparently had little or no natural defense against the parasites. Many parasitic infestations are self limiting in that their life spans and the host's immune system combine to keep an infestation from getting out of hand. It's counterproductive to kill the host. Because our fish lacked the ability to ward off the copepods , whether through natural immunity or stress , the problem quickly got out of hand.

Complicating things further , the harsh winter of 2002/03 caused a winter kill of shad. Being unable to find enough food weakened and stressed the Stripers to a point that allowed the copepods free reign. Actheres and a wicked combination of weather related problems would cripple the trophy Striped Bass fishery at Smith Mountain Lake in just a few short months.....

Check back tomorrow for Part 3 !

2 comments:

  1. The one Rainbow that I came across that had Copepods didn't look all that healthy. It was when the lake water was warm, too.

    Mark

    ReplyDelete
  2. It's interesting that you saw them in warm water out in Northern CA....

    Thanks for stopping by Mark! I'm loving the snow you guys have right now and the rotating header images you have!

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