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Monday, April 21, 2014

Sea Lice, Estuary Lice or Freshwater Lice?

I was was fishing with Blake Larsen last week and a number of fish caught had lice on their gill plates. This brings up a couple of thoughts to ponder.

Are they sea lice, estuary lice, or freshwater lice?

I have often heard of these lice being referred to as sea lice. But in order for the lice to be sea lice the caught fish would have to be a steelhead that has gone all the way to the ocean. We have heard from researchers that only as little as 5 to10 percent of the Lower Yuba fish make it to the ocean. This has been documented by a scale survey done a number of years ago. So, if they are sea lice then this fish was one of that percentile.

I have also heard from fishery biologists that a percentage of Lower Yuba fish that have anadromous genes run to the estuary waters, feed, and then run back to the Lower Yuba. If that is the case could this fish be a steelhead that doesn't make it to the ocean, but goes as far as the delta saltwater? Could the lice be estuary lice?

Lastly, it has been documented that most of the Lower Yuba trout are resident fish and move in and out of the Lower Yuba, sometimes into the Feather and back and forth during the high flows of winter and back in the spring. Could this have been one of these fish? Could the lice be freshwater lice?

The lice present interesting points to ponder. I don't have the answers. Any thoughts?



  1. your answer

  2. I remember having a conversation with a fish biologist that worked for the DFG and he stated that it was his opinion that the andramous Lower Yuba River trout/steelhead traveled out of the river and into the delta until they would hit the brackish salty water, feed there and then head back up. He believed that that's the reason the rainbow/steelhead are smaller than their Northern California cousins. This may account for the freshwater lice.



Have any Questions or Comments? Let me know, Clay.