Does Herbicide treatment mess with bass?

[TriStateBassin106]

Hey BR,

 

Yesterday I fished my first tournament of 2020 on a lake up here in Northern NJ, me and the guide I was with noticed that the lake had a very low amount of sub surface aquatic plant life compared to years prior, after a very slow bite for most of the morning on a lake that usually produces fairly well it was revealed that the lake we were fishing was treated to kill off excessive weed growth this past Monday, does this have an effect on fish? Specifically bass? I was talking with some of the other anglers out on the water after our tournament and they told me it could mess with the bite for at least 2 weeks.. is this true? 

[Logan S]

I've fished lakes that have been sprayed or treated and the fishing has always been poor for a period of time after.  Our DNR has said the herbicides don't effect fish and while that might literally be true (as in it doesn't kill them outright) it definitely has adverse effects on the fish.  I generally avoid areas that have been sprayed if I can.  The fish I have caught in those areas are frequently skinny and rough looking.  

 

Everyone I know has similar observations...I've never heard anything positive about treating SAV with chemicals in regards to fishing quality.  

[813basstard]

^that. 
 

In my completely unscientific theory, I would say the fish move away from whatever they’re spraying.

More importantly, you fish tourney’s with a guide??

 

Nice!

[Bluebasser86]

Dying plant matter sucks oxygen from the surrounding water. Bass and baitfish will leave the area until things settle down. They treat some lakes around here and the fishing is about impossible until a couple weeks or even a month later. Fishing has never been the same since they started treating them though. Algae blooms are very bad and water clarity is not nearly as good as it use to be.

[Bankbeater]

We've had some local lakes treated around here.  A lake I fish used to have coontail all through it, and mats on the surface.  Now this lake just has water willows growing around the bank.  While I don't think it physically harms the fish, I think it changes the way they feed. 

[Captain Phil]

Aquatic weed spraying does not kill fish.  As others have stated, it relocates them.  If your house was bombed and your food was removed, would you hang around?  :>)

[TriStateBassin106]

3 hours ago, Bankbeater said:

We've had some local lakes treated around here.  A lake I fish used to have coontail all through it, and mats on the surface.  Now this lake just has water willows growing around the bank.  While I don't think it physically harms the fish, I think it changes the way they feed. 

How so? Do the fish relocate to areas that still hold baitfish? 

[Dogface]

10 hours ago, Bluebasser86 said:

Dying plant matter sucks oxygen from the surrounding water. Bass and baitfish will leave the area until things settle down.

I treat a friend's pond in NE PA. The instructions on the treatment recommend doing the pond in stages because the dead weeds will deplete the oxygen in the water. 

 

The pond is only about 8 acres but I do it in four stages over a period of 4 weeks. 

[Bankbeater]

9 hours ago, TriStateBassin106 said:

How so? Do the fish relocate to areas that still hold baitfish? 

I know the lakes turn murky without the vegetation to filter the water, muddy when it rains. I think the predator fish need to learn how to hunt baitfish without vegetation to hide in. 

[K1500]

You fish tournaments with a guide? I think dying vegetation can definitely mess with bass fishing/patterns. 

[TriStateBassin106]

9 hours ago, K1500 said:

You fish tournaments with a guide? I think dying vegetation can definitely mess with bass fishing/patterns. 

I used the word incorrectly, just another angler who knows the lake really well. 

[frogflogger]

The verdict on herbacides is still out - there has been quite a bit of research showing some issues for fish health. But no matter it does make them move.

[K1500]

Thanks for the reply, I’m not really a tournament guy so I didn’t know if that was a thing. I can see how herbicides would change the fishing pattern in a lake, perhaps quite drastically. I have no idea about mortality, but I would guess that catch rates decrease for a while. 

[TriStateBassin106]

19 minutes ago, K1500 said:

Thanks for the reply, I’m not really a tournament guy so I didn’t know if that was a thing. I can see how herbicides would change the fishing pattern in a lake, perhaps quite drastically. I have no idea about mortality, but I would guess that catch rates decrease for a while. 

I don't mind grass as long as it's not an infestation, submerged weed beds can have some of the best fishing, taking too much of that away either makes the fish go deep and suspend, or they'll just be lockjawed