Pond Boss Forums POND CONSTRUCTION Renovating a Pond or Lake? selective killing of gizzard shad

Hi everyone, love this site, the Pondbossman is the best.

Does anyone have experience with selective killing of gizzard shad?
They have taken over our 10 acre Michigan Lake - DNR says kill all the fish, fish survey people say stock more bass, fish farm guy said get pike, Pondboss says no pike, homeowners won't want to kill all the fish. There are lots of sites on the internet regarding low does fish kill that will kill the shad, but nobody recommened this.
I subscribe!

can someone explain why it says fingerling underneath my name?

You havent had enough post yet. Once you have 10 post it will change to lunker.

do you know anything about gizzard shad?

Does Pond Boss really say no pike? I'm going to stock them...

I don't think PB says no Pike. Like all other fish they have to be managed correctly or you can have problems.

GShad can cause problems as they get to large for most all predators. What size are the GShad that you see ? Also GShad if not greatly suppressed by predation can deplete the plankton supply and also suppress reproduction by other species. It is not uncommon for GShad if out of control to take over a pond and fill up a large part of the biomass. To control a GShad population with LMB you will need a high % of LMB over 18 inches + and even then it can be a challenge.

Large pike can help but it would be good to not have a breeding population of them in the pond.

Is this what you have - large northern GShad ?









Some possible options other than rotenone are gill nets or electrofishing deployed by fisheries scientists.

I would start a Muskie stocking program and start off heavy to the shad back under control.

Muskie will not reproduce and they will hunt down the gizzard shad.
For your situation, stock 3 per acre ASAP. Then stock one or two per acre every year until the shad are under control and you are infested with 15+ lb muskie!

Also for your consideration: Tiger Muskie grow faster and dont live as long as pure strain muskie. If the shad population gets back under control and you dont want the muskie anymore, dont stock them anymore and ecourage folks to harvest them! Muskie will hunt down all the gizzard shad before they will hunt for other gamefish. Also once the big shad are gone, Hybrid Striped Bass do a better job at hunting down the yoy gizzards than LMB do.

Survival, Growth, and Prey of Esocidae in

Experimental Systems

A. STEPHEN WEITHMAN AND RICHARD O. ANDERSON



Prey Vulnerability

Vulnerability to esocid predation was

highest for gizzard shad, goldfish, and

golden shiners, intermediate for bluegills

and largemouth bass, and lowest for channel

catfish. Variability in the results of six

prey-vulnerability trials was low; values

were averaged and presented as a percentage

of numbers eaten per number offered

for each prey species (Fig. 4). The largest

variation was in goldfish vulnerability; hybrids

consumed 35%, as compared with 58%

by northern pike and 62% by muskellunge

(Fig. 4). Electivity values (Ivlev 1961) were

positive for gizzard shad, goldfish, golden

shiners, and bluegills, near zero for

largemouth bass, and were negative for

channel catfish (Table 3).





Esocids in general, and

the hybrid in particular, should be able to

consume adult gizzard shad at a younger age

than other game fish.

Many studies have been conducted on the

food preference of esocids, especially

northern pike. Some investigators have reported

that esocids are piscivorous and feed

indiscriminately (Frost 1954; Crossman

1962); others have found that when given a

choice, northern pike prefer non-game over

game species (Beyerie and Williams 1%8;

Hunt 1965). We concur with the second

group--that when given a choice of prey

species, esocids feed selectively. In Pomme

de Terre Reservoir, muskellunge consumed

gizzard shad, carp (Cyprinus carpio), and

bluegills in that order (Vasey 1968). In confinement,

northern pike preferred gizzard

shad and carp over largemouth bass and

bluegills (Mauck and Coble 1971).

Wow, how exciting to get such good ideas. We had the lake electofished and a fish survey done. It came out something like 45% gizzard shad, 40% Bluegill, 5% LM Bass,some carp, but not a problem, but they felt there were not a enough 1, 2 & 3 year old Bass. They removed 7 carp, 35 lbs of g. shad. There were some very big LM, the bluegill are pretty small (but they said not quite a stunted population) and the average size of the g.shad was 9.5" long. They are skinny compared to the ones in the photos, and we have 1-2 cormorants eating them in most of the summer.
The lake has been mismanaged, with outflow left open by the city, with county draining ditch backflowing into the lake (maybe the shad came in there, it is closed for a year now). The lake has way too many storm drains and run-off, water testing of water coming in through the drains before, initial wash, 10 minutes into , and next day reveals off the charts nitrates and phosphates. We are banning phos., and working with the city to try and divert some of the drains, salt is not used in the sub, but some is coming in from 1 drain out of the sub. Bad treatment company had a kid here for 3 seasons that just bombed the hell out of us with copper sulfate, and killed all living vegetation in the lake, trying to control the plantonic algae that arrives the 2nd week in June for 5 years now, lake was being treated a month too late for the curly leaf pondweed which was allowed to become the dominant plant. They killed off all the Chara. We got them out of here and a new great company in here. The white scum is gone, but we still have the plank. algae, they can control it, but nothing works more than 6-8 days, we want to try a bacteria bioremediation program but have to fight hard for that like everything else. I can watch the water go from decent, to planktonic algae on a windy day in June. So once the water hits 72, we get green bubbles on the surface in the morning that move very slowing into shore on days with no wind. The thought is that the g.shad are contributing to the nutrient load by 1> the mass of them, 2> how they stir up the bottom, 3>how the eat so much zooplankton. The 2002 sediment survey revealed 1-4" with average about 2" buildup on the bottom. It is a former gravel pit, sandy, spring fed lake developed in the late 70"s, and is 8" deep. It is mostly been a beautiful swimming lake, paddleboats, sailboats, no motors,no serious fishermen. There is no flushing rate. This past year the lake started off murky right from the start for the first time, and clarity was about 21" most of the season, no native seed bank, nothing grew back in. We have to get some good pondweeds going this spring (Sago, American, Illinois and the Chara back), nothing is holding the sediment down or taking up nutrients.
I think the problem with the pike is that we go from g.shad heavy to pike heavy - so if the Tiger Muskie don't reproduce, that sounds good to me. And if they are easy to remove later, that would be good too, one bit a child here in Tipsico lake (I think) a few years back. The fish guys were surprised that with the hard winter we had last year the g.shad didn't die off. We have had some LMBass spawing boxes made, and have to figure out some good cover to attach (we are told that will funtion for the minnows too, which we aren't seeing much of now either).
The low dose fish kill sounds good to me, but nobody else thinks that is a good idea.
Thank you all you good people trying to help me solve this problem. I love my lake, so sad to see this happen to it.
Lynda

Your situation sounds like a typical subdivision lake!

I bet the muskie was out of the water when it bit a child a few years ago?? if not, that is the first attack I have heard of.

Keep us updated on your progress.

One question:
Why won't the tiger muskie reproduce?

Is is possible to drain the lake? If you could at least mostly drain it, a good Michigan winter would likely kill off most if not all of the shad.

Like many hybrids, Tiger Muskies are effectively sterile.

at 9.5 inches not that bad a situation, if you can stock some adult bass you should see outstanding growth.

Some big adult LMB. At 9 inches you need LMB 2 to 3 times that long or 18 to 27 inches. Not easy to find. To get control by predation I would try to find both big LMB and T. Muskie.

with gizzard shad at 9.5 inches the LMB would have to be about 19 inches right? I guess your best bet would be to go fishing and catch some 19 inch LMB. How many LMB would it take to solve the problem?

I guess my point is that it is not a huge problem quite yet compared to some lakes we shock with lots of 15-18 inch gizzard shad. Yes you need a big predator but more bass in general would help keep the smaller gizzards in check.

When they electrofished the lake I stayed out there till 3:00 a.m. at the weighing station. They were amazed at how large some of those LM were, one even had a g. shad with his tail sticking out of his mouth. They massaged those nice big fish back into the water too. But they thought that we were pretty well infested with the shad, and the total dissolved solids were off the charts and it was about June 20th at that time. Would the g.shad get as big as those in the above photos here in Michigan?
Thank you all so much for your advice and help. What does HTML disabled and UBB Code is enabled mean?
Lynda

Those GShad pics were from South Dakota and yes Mich can grow them just as big especially in a fertile pond like this one.

Wow, that is scary. Someone asked if we can drain the lake? I though I answered but it didn't show up. We have a 12" outflow to the county creek, they would have to put a pump in to pump some water out, but nobody has ever considered even draining a few inches out in the winter for erosion control. Our lake stays high compared to some of the other five. How low would we need to drain to kill off the shad, and would it hurt the other fish?
Lynda

I would use the gizzard shad to my advantage to keep growing insanely huge gamefish! Keep the bass how they are, dont stock any more. Then stock the tiger muskies ASAP. Also this fall I would start a WALLEYE stocking program as well. Stock them heavy due to the abundance of forage: 40-50 per acre every year and encourage folks to catch and eat the big fish!!!

After a few years you may want to introduce more gizzard shad to keep fueling the most popular fishery in Michigan.

How big is this lake?

I'm not sure if drawing down would work but since someone told you they were surprised they were surviving the winter the idea came to mind. I'm no expert but I'd guess it would depend on how deep the pond is and how much water is flowing through.
http://blog.mlive.com/chronicle/2008/04/dnr_official_lake_fish_kill_li.html

A drawdown would also decrease shorline vegetation. There was a good article in PB magazine about this recently.

I think I read somewhere that HSB were not legal to stock in MI, but are pure blood stripers? Either are effective predators of the shad if legal. I have gizzard shad in my pond and they quickly grew to 15" or 16" but have been kept in check by HSB.

What about inducing a shad kill by supercooling the water? Gizzard shad die at ~ 40F normally. Diffusers placed in the deepest water of the lake and run during some cold weather could certainly drop the water temps enough to kill them.

You wouldn't get rid of all the shad, but it would be a good starting point to knock them back while you establish a better predator population to control them in the future.

DO levels would be a concern when all those fish start to decompose though....

Nate - see prior posts - 10 acres - nearly stunted BG and 45% GShad and 5% LMB as measured by fisheries scientist by electroshock. "DNR says kill all the fish, fish survey people say stock more bass, fish farm guy said get pike..."

As they indicated , you need to deal with the GShad. In a normal pond IMO GShad should not be viewed as just another forage fish because of their ability to take over large %s of carrying capacity and suppress both growth and reproduction of other fish species. There is a reason you only have 5% LMB and near stunted BG. My guess is suppression of LMB spawning by GShad and BG and predation on LMB yoy by small BG. BG are starving due to competition with GShad and not enough predation by low #s of LMB.

IMO a combination of the advice of the FS and hatchery guy is the best advice. Add large LMB and T. Muskie at least until the average size of GShad is 4 to 5 inches and you have good populations of healthy predators and adequate #s of all sizes of BG.

Although not high on many's list of favorite fish, channel cats get big fast and I've witnessed them attacking schools of gizzard shad in lakes here in Ohio. Actually some of my best catfishing was done during these times by cast netting some shad, putting them on a hook and tossing them back into the school. The bait rarely sank more than a few feet before a CC would grab it.