Question for biologists or anyone else.

Hey guys

I've noticed something considerably different about the spotted bass I've been catching recently at Shasta; They're wormy. I rarely see worms in Shasta bass, I'm assuming it's because the water fluctuates so much that the water quality is very good. I guess that with the lake being so low and very little water entering the lake,  it makes an opportunity for parasites. I have yet to see any muscular worms, it's the occasional gut stuffed full of segmented tapeworms, or as is the case recently with 90% of the bass I've cleaned,  a weird squiggly worm that seems to reside in the fatty deposits attached to the ribs in the belly cavity.

Anyhoo, I was wondering if CADFW has any treatment capability of an issue like this.

On a side note: I was also wondering what kind of an impact the clam die-off due to low water conditions may have on parasitic activity. If I remember correctly,  an adult freshwater clam (little yellow to dark brown guys) bivalve filter 3 gal. In a 24 hour period.  I've noticed that there are 250 yard wide clam beds that are dead and sun baked all around Shasta. This has to have a significant impact. Does CADFW have a clam seeding program at all? I expect it wouldn't take long to get a healthy clam population up and going again.

Thanks
Jesse

I forwarded your questions to a colleague of mine who is a reservoir biologist in that area.  Will let you know what he says.  I also forwarded the wormy bass questions to a college friend who did his thesis on black bass parasites.  Hopefully they can shed some light.

Awesome Clayman! Thanks a lot!

This is the response I received from the reservoir bio:

Thanks for the questions.  As far as seeing an increase in parasites in the bass he has been cleaning from the lake, I have not seen that myself.  Fish from most of our reservoirs often have external and internal parasites, as far as low water (drought) increasing this problem, I have no data confirming this situation.  It may be possible that bass in higher concentrations due to low water may be stressed and more susceptible to parasitic invasions.  Let your friend know that consumption is fine, just cook fully and discard the internal organs.  The clams found at Shasta Lake are the Corbicula (Asiatic) clam and are not native. The department does not have any programs doing research of cultivation of freshwater aquatic mussels like many other states do. I am not an expert mussels and how or if Corbicula fluminea is an intermediate host for parasitic tapeworms. I suggest your friend do an internet search to gather more information.  With the drought and the demise of so many Corbicula, my guess that if Corbicula is related to the increase in fish parasitic activity, it is intuitive that decreased Corbicula would result in fewer parasites, if they are indeed connected.  Just my thoughts. Give my information to your friend if he needs further information.  I can get him in touch with our invasive species staff.

Interesting stuff.  I haven't bonked a Shasta bass since the spring and those were all clean.  I would imagine the tighter concentrations of fish (like waterfowl) could certainly play a role in a higher rate of transmission. 

I hadn't thought about clams being host to the parasites. I was thinking that the massive population of clams would help with filtration and water quality; somewhat like what happened with the zebra mussels in the great lakes. I imagine that the low water, lack of current and very little bivalve filtration would all be factors.

After this storm I'll get another limit and take pics of the parasites and post them.  I've been fishing between the dam and digger bay if your reservoir biologist friend is interested. I fished 5 consecutive days last week and maybe one or two fish didn't have parasites,  so it's pretty bad.

Maybe less water = warmer temps = more stress on fish = more susceptible to parasites?

It is also possible that there isn't an increase in parasitic infections, and that you just got unlucky with a few wormy bass.

It is also possible that there isn't an increase in parasitic infections, and that you just got unlucky with a few wormy bass.

Damn scientists trying to ruin a perfectly good theory 

It is also possible that there isn't an increase in parasitic infections, and that you just got unlucky with a few wormy bass.

Possible but unlikely. I catch and eat spots very often at Shasta. I think other people could back me up that there is very little parasitic activity with the bass here. I cleaned 25 spots last week,  maybe two didn't have their bellies full of worms.

Maybe less water = warmer temps = more stress on fish = more susceptible to parasites?

+1

This is the response I received from a school friend of mine who did his Master's working with parasites of largemouth bass:

As for the reason behind why he's seeing more parasites, I couldn't guess. Frankly, from what I've seen, some bass loaded with parasites, some not. I haven't seen a real trend. Long segmented tapeworms in the digestive tract are common enough. I'm sure there are more than a few different species it could be, but the ones I found in LMB were Proteocephalus pearsei. As for the worms in the body cavity, I'm assuming nematodes; juvenile Contracaecum sp. The reason he's not seeing the muscular worms (like in rockfish) is that as far as I know, the Contracaecum don't have the same inclination as Anasakis simplex to cruise out of the gut into the flesh. There are a lot of other parasites in the digestive tract that aren't terribly big, so he's probably not noticing them; Acanthocephala, Spinitectus sp. Camallanus sp. and surely some other stuff. You make no mention of ecto-parasites; any leeches, encysted worms in the fins, etc?

I made Shasta spotted bass ceviche one time and mentioned it to our fish bio at work.  After a lesson similar to that above, I will not be partaking in that again.  Filthy buggers.

I made Shasta spotted bass ceviche one time and mentioned it to our fish bio at work.  After a lesson similar to that above, I will not be partaking in that again.  Filthy buggers.

Haha, some years ago when I really got into sushi, I asked myself "why doesn't anyone eat freshwater fish sashimi?" After some research, I found out why.  Such a bummer!

It is a bummer, because it actually came out really good!  I stick to pre-frozen rockfish fillets from now on though.