DWR Update on White Bass Dieoff

[TubeDude]

Several of us Utah Lakeophiles have been carrying on an ongoing discussion and speculations on what happened to the white bass in Utah Lake.  There was an observed major dieoff of adult white bass shortly after iceout.  And even after the effects of that dieoff diminished, the number of white bass available anywhere on the lake has been dismal...compared to past years.  Nobody I know of has made any kind of multiple catches on white bass since they grouped up off the mouth of the Provo River for spawning.  One or two random fish per trip is the norm.

I have been maintaining contact with Chris Crockett...of the Springville DWR offices.   I recently sent him a request for any updates on the white bass situation and he contacted some of the biologists who had conducted pathology studies on the deceased white bass earlier in the year.  Here is his reply.  Thanks again, Chris.
    
In April white bass fish kills occurred at several places around Utah Lake.  After dead fish had been reported in various placed on the lake, moribund white bass were collected to attempt to determine the cause of the die-off. Examination showed that in general the fish appeared normal but they were not eating and the entire gastrointestinal tracts were empty. An aeromonad bacterium was isolated but fish did not exhibit clinical signs of infection. At the time there had been a 3-day warming event, early spring reservoir conditions were noted and the white bass population was immediately pre-spawn.  Spring can be a time when any type of stress from things like spawning, opportunistic infections, high water temperatures or other water quality issues, can cause fish die-offs.  While no abnormal water quality or toxic algae were noted during the event, factors that were not recorded could have been impacting the lake. There are often multiple causes contributing to fish death and in this case, mortality likely occurred due to a combination of the variables listed above with the bacterial isolate occurring as a stress related manifestation. Additional samples were collected in May to further evaluate body condition and bacterial presence.  At that time the bacterium was isolated from a few fish but overall the population appeared to be healthy and had resumed eating. No further reports of dead or moribund fish were reported.

[joatmon]

Thanks Pat. I can confirm it has been slow and the few white bass I have caught tend to be more in the 6-8" range than in the 10-12" range. Any thoughts on how the spawn was affected and how that might affect white bass populations in the next 1-2 years? For instance, will the white bass fry be hit harder resulting in less adult recruitment? I have seen an increase in bullhead cats this year and don't know if it is related. Lots of moving parts in a multispecies shallow water body. We may never fully know the causes, but hope the effects aren't long term or widespread.

[TubeDude]

Thanks Pat.  I can confirm it has been slow and the few white bass I have caught tend to be more in the 6-8" range than in the 10-12" range.  Any thoughts on how the spawn was affected and how that might affect white bass populations in the next 1-2 years?  For instance, will the white bass fry be hit harder resulting in less adult recruitment?  I have seen an increase in bullhead cats this year and don't know if it is related.  Lots of moving parts in a multispecies shallow water body.  We may never fully know the causes, but hope the effects aren't long term or widespread.

I suspect that largely due to the adult whitie die off that the spawn was poor this year.  At least I have not seen nor heard of any 2" white bass fry showing up to chow down on the morning midge hatch anywhere around the lake.  Most years by this time the inshore waters are boiling with whitettes and a few big splashes from predators feeding on the little tykes.  Not this year.   If no 3-4 inchers show up in the next few weeks we (and the predators) are due for some lean times.

If, in fact, the food chain has been thus disrupted I expect to see a repeat of the winter of 2004 -2005.  During the late fall and early winter the walleyes were much easier to catch because they were hungry...from a lack of baby white bass.  But many large walleye starved and died under the ice that winter.  And any walleyes that made it through the winter were mere "hammer handles" in the spring...skinny with big heads.   


Might be good to see an increase in bullhead numbers.  Walleyes turn to them as a calorie source when there is nothing else on the menu.  During lean times I have filleted a lot of walleyes with bullheads in their innards.

[Piscophilic]

Hey Pat,

Thanks for the update. I had been meaning to check back with Chris but I just plain forgot. I think it is interesting that none of the dead whites sampled had anything in their stomachs. I doubt if lack of food supply would have caused that, but more likely some kind of disease or something that made them not eat. Just a guess though.

I have also been watching closely for the arrival of the YOY whites and have seen none. I looked back at my earlier years records and did find one year that I didn't report catching any until Sept 1. I'm still holding out hope that they will show up in modest numbers based on many observations that the spawns for several species seemed to be delayed a couple weeks this spring. In fact one of the 30" cats that Jon got Saturday was all torn up and caught when we were dragging over shallow rocks looking for white bass. Clearly that one was a late spawner, but just finishing in Mid-August seems later than usual even for a slow one.

[TubeDude]

Hey Pat,

Thanks for the update. I had been meaning to check back with Chris but I just plain forgot. I think it is interesting that none of the dead whites sampled had anything in their stomachs. I doubt if lack of food supply would have caused that, but more likely some kind of disease or something that made them not eat. Just a guess though.

I have also been watching closely for the arrival of the YOY whites and have seen none. I looked back at my earlier years records and did find one year that I didn't report catching any until Sept 1. I'm still holding out hope that they will show up in modest numbers based on many observations that the spawns for several species seemed to be delayed a couple weeks this spring. In fact one of the 30" cats that Jon got Saturday was all torn up and caught when we were dragging over shallow rocks looking for white bass. Clearly that one was a late spawner, but just finishing in Mid-August seems later than usual even for a slow one.

Yeah, it was a wierd year weatherwise and spawnwise for several species.  But I am beginning to wonder...what is the real "normal".  Every year seems to be different.  I will also not panic until I do not see any YOY whities after September.

[Big Sky]

Pat thank you for sharing this information.