Pond Boss Forums INTRO Questions & Observations Shad!

Last night while feeding I saw what I thought was a small school of recently hatched tilapia. I threw out the cast net and after a closer look they were gizzard shad about 1.5" long! I don't know exactly how they got there but I have some ideas. The sizes coincide nicely to when I was on vacation. Dumped minnow bucket? Catfishing with shad? I'm investigating any guests that may have visited while I was gone.

This will really change the management plan. This is a 1/2 acre pond pond with a good base of BG and FHs and some tilapia. There are 40 bass and 15 large CC. There are few weeds. I have read the posts from ML and Bill Cody and I would not have stocked these fish in my situation but it doesn't sound like I can get them out so the best I can do is try to control them. I have been debating on stocking HSB for a while now and it sounds like their open water feeding characteristics may help in contolling the shad. Will 10 be enough? or should I wait until next year and see what happens? I suspect this also means I can't/shouldn't stock tilapia next year? Do I need more LMB? How bad is this situation?

I think I would try to get as many as possible out with the net. GSD have some very bad possible consequences in a pond with out very large LMB. In studies GSD have the tendency to grow fast as a population until pond carrying capacity is reached then they repress all fish reproduction so they can grow large and there are few new fish offspring. A pond with 50%+ of its carrying capacity in GSD is not a good option IMO unless you have good numbers of 20+ in. LMB.

Ryan,

Interesting how we try and try to manage our ponds according to our plan, but seems like something always happens to undo our best efforts...at least it always seems to work that way with me. Frustrating, but it does keep things interesting.

My experience with gizzards turned out to be a total non-event. I stocked them and the predators eliminated them. Never even got the chance to see if they were helpful or harmful. The HSB were a major factor in gizzard elimination, I believe. The gizzards stayed primarily in open water where they were easy targets for the HSB. While the gizzards are small, the HSB can really rip them up.

However, if the gizzards get too large for the relatively small mouth of the HSB, then the large LMB is the best hope to control/eliminate them.

If the gizzards are only 1.5 inches now, stocking HSB before the gizzards grow much larger would seem to be a logical approach. Also, after Tilapia die-out this year, the forage choices are somewhat reduced and perhaps the HSB in combo with the LMB would then be more effective on the gizzards.

Stocking the HSB in your area of the country seems like a low risk option. However, you need to find HSB that are large enough to avoid LMB predation.

As far as re-stocking Tilapia next spring, assuming you stock HSB now as part of a gizzard elimination approach, I think I would wait until spring to decide on Tilapia and base my decision on what the gizzard situation looked like at that time. To eliminate gizzards, it seems you would need to focus the predators on them and not offer Tilapia to the predators as alternative forage.

I have mixed feelings about loosing all the gizzards in my pond. On the one hand, it would have been interesting to see what they could do for the top-end large Florida LMB, but on the other hand, in order to effectively control them I probably couldn’t stock Tilapia also. Tilapia has proven to be a far better choice for me in my ponds.

Ryan:

FYI a PB thread and excerpts from 2 studies (and there are more) on GSD.

http://www.pondboss.com/ubb/ultimatebb.php?ubb=get_topic;f=5;t=000214#000001


EXPERIMENTS WITH COMBINATIONS OF LARGEMOUTH

BLACK BASS, BLUEGILLS, AND MINNOWS IN PONDS

by H. S. Swingle

In this experiment , a pond was stocked with 1,000 bluegills and 48 shad per acrein October 1941, and 200 bass fry per acre were added the following May. The pond was drained in November 1943. In 1942 gizzard shad began to hatch in the middle of March and continued into July. The first bluegills hatched in early May and spawning occurred at intervals the rest of the season. No shad hatched in 1943 but bluegills spawned lightly from July until fall. Largemouth bass grew rapidly, reaching a size of 7 ounces by August 8, 1942. At that time the young gizzard shad were still small enough to be eaten by the bass. In 1943, the shad reached a size of 1.5 to 2 ounces by the middle of the summer, and when the pond was drained in November, there were 516 pounds of gizzard shad per acre, the smallest being too large for the largest bass to eat. This combination produced 101 pounds of largemouth bass, 173 pounds of bluegills, and 516 pounds of gizzard shad, or a total of 790 pounds of fish per acre. Of this total weight, 65.3 percent was shad, 12.7 percent bass, 13.5 percent adult bluegills and 8.5 percent young bluegills.

During the second year, gizzard shad reproduced only sparingly or not at all, apparently due to overcrowding by large shad, bluegills, or both.


Management of Forage Fishes in Impoundments of the

Southern United States

by RICHARD L. NOBLE

They frequently become overpopulated and affect other species. For example, Jenkins (1957a) com-
pared fish populations in two nearby lakes, one having 560 kg/hectare of gizzard shad, the oth-
er lacking this species; in the presence of gizzard shad, game fish had a lower standing crop,and centrarchids had slower growth, poorer condition, and smaller average size than where
gizzard shad were absent. Swingle (1950) found that when gizzard shad became overpopulated
at sizes larger than those readily vulnerable to predation, they reduced or prevented produc-
tion of forage-size bluegills and gizzard shad, thereby reducing growth and survival of young
largemouth bass. In spite of its major contribution to food of predators, the gizzard shad remains a problematic species due to its propensity to develop high biomass of large individuals with the potential to interfere with production of other species.

I noticed 3 or 4 clouds of fry about 3'across when I returned from vacation. I have observed the BG and LMB putting a lot of pressure on them. Last night I only saw two schools and there were less fish. I haven't had any experience with HSB in ponds, would they outperform 18" LMB in controlling shad?

Ewest, thanks for the info. A significant difference in my pond and the Swingle experiment is that I have at least 80lbs LMB per acre compared to 200 fry. I seriously doubt that I have 280lbs of shad and I have been catching 9"-10" BG so my situation does not appear to be as bad as it was at the end of Swindle's experiment. I read the post that you linked to before I started this thread and reread Bill Cody's section, not because it wasn't well written, but because there was so much information. All the information I have read leads me to draining the pond unless I have 24" bass, which are very rare in Ohio. This is the third year since the pond was built and I would hate to drain it and start over. I have searched the site and have found some great info on why to and why not to stock gizzard shad but have yet to find an example of a Northern pond with a shad overpopulation problem. Open water is a fairly relative term. How big is the "open water" section of a 1/2 acre pond? It seems that the LMB utilize my entire pond so a HSB's open water preferences my be insignificant in my case and LMB would definetly be more capable of consuming larger shad.

This my be way off but...if the shad eat the food of the BG and LMB fry, wouldn't that give the larger LMB and BG less competition? Wouldn't the lack of food for the fry result in more small BG and therefore more small forage for the bass? Then lack of BG growth for forage would be supplemented by shad?

I don't recall anyone suggesting that draining was an option. The Swingle study was to show their growth and ability to fill up a large part of a ponds carrying capacity. The Noble study was to show that they develop a high biomass of large individuals with the potential to interfere with production of other species.

The My suggestion was to cast net what you could. If some good sized number survive 1 year they will outgrow the ability of your LMB to eat them. If they are successful at reproduction their offspring will compete with your yoy of all kinds. When they get big they can (some think chemically or by a combo with plankton depletion) stop reproduction/survival of other species in the pond. The result could be a large % of your ponds carrying capacity tied up in GSD. If that risk is ok with you then it is ok with me -- your pond and your question. Here is another study with a chart showing an easy to understand comparison.

THE EFFECT OF GIZZARD SHAD ON THE FISH
POPULATION OF A SMALL OKLAHOMA LAKE
ROBERT M. JENKINS
Oklahoma Fisheries Research Laboratory

The faster growth,
plumper condition, and greater average length of fishes in the lake without shad
indicated that direct interspecific competition occurs between centrarchids and
gizzard shad in small-lake populations.

Ryan,

My 2 cents worth....draining your pond and starting over is a drastic measure, one taken only when all other options are exhausted. Like most pond issues/questions, there are at least two ways of looking at any problem...and usually more. Which is the right way?

I'd encourage you to read the May/June 04 Pond Boss article for another view. The article, written by Kedric Nutt and based on research by Dr. DeVries, provides a less ominous view of gizzard shad. In addition, note Todd Overton's comments on the referenced thread about his experience with gizzard shad. He recommended gizzard shad to me...but as I mentioned they did not survive.

With that as background and your own anecdotal evidence regarding take-overs by gizzards, my advice is don't panic too soon. Draining the pond and starting over is an option that will always be available.

First, certainly before draining, a predator heavy approach should be tried. Augmenting the LMB with HSB to remove the smaller shad and prevent them from getting to the large size is one option to try. You could easily add 20 HSB to your 1/2 acre, let them work and then remove some in a year or so depending on how things look. In fact, a put and take fishery with HSB where you add a few every year and remove a few for eating, is not a bad way to go. If you can't find HSB in a larger size (8 to 9 inches), then stock the smaller ones expecting a 50% mortality to predation. If mortality is higher than that, then simply stock more of them. The cost of a few HSB is very small compared to draining and starting over and the time lost with that approach. In fact, it may well be cheaper to buy more of the smaller HSB fish than paying a premium for large HSB.

In my view, the HSB will do a couple of things: 1) they will consume large amounts of any small gizzards and 2) they will also consume other small forage e.g. BG and Tilapia and help the LMB concentrate on larger gizzard shad. As a bonus, they will give you great fishing action. You don't have the summer high temps for long periods of time like we have in Texas and hence that problem isn't much of an issue for you.

What's the worst that can happen with this option? If it does not work, you can still drain the pond and start over....and have a huge fish fry of HSB and fat LMB.

Using a cast net may help some briefly, but I doubt it, because over time the gizzards will get very difficult to catch that way. The small gizzards need to be eliminated...HSB can help do that...and the large gizzards need to be reduced...LMB can do that. To optimize the HSB effectiveness, I think I would also limit artificial feeding....encourage the HSB to eat shad, not pellets.

Obviously, Ryan, I'm not in Ohio and do not have Ohio pond experience. I'm offering my thoughts based on my own experiences and in hopes it can help you in some way. Good luck.

My channels seem to have filled the niche of open water predators, much like blue cats. This is the second fish I have caught on a dying minnow presentation, the first was a senko, this was a tube. Both were taken on the fall about 3' down. Shortly after catching this channel another broke me off.


It seems that HSB get a little more respect than CC but it would seem that these large channels would be able to consume larger shad than the HSB.

Ryan, I agree with ML about increasing your predator base with LMB and/or HSB to attempt to control your gizzard shad.

I don’t agree however, on his thoughts about stocking fingerling HSB with adult predators.
Predation has been much higher than 50% in my case – perhaps closer to 80+ %.
In order to maximize predation, I would stock the largest HSB available.

IMO, ML was pushing the envelope with his experimental GSD program, based on personal emails at the time.

Personally, I do not think CC on steroids are fast enough to catch gizzard shad…

Good luck with your GS elimination problem – I would hit them hard and I would hit them fast with largest predators available – a bargain compared against draining and starting over.

N.E. Texas

I appreciate everyones facts and opinions. It sounds like everyone collectively agrees that my best bet is going to be some larger HSB. I had an opportunity to get some larger ones earlier this year and somewhat regret not doing so.

I stocked 20 6"-8" HSB yesterday evening. I went out about a half hour after stocking and one was laying on the rocks. I pushed him back in and it smam off. An hour later I observed the a HSB chasing minnows along the bank so the transfer must not have been too traumatic.

Ryan- Do you know what your water temperature was when you stocked the HSB? I was going to stock some when the temperature falls a few degrees here in central Texas.

Here's a different spin than what I have read in this thread.
Part of the fun with fish management is speculating what might happen, then responding accordingly, such as stocking the hybrid striped bass because of the gizzard shad school.
Always keep in mind that fish populations are dynamic...always changing. Just because we see a school of small bass in May doesn't mean we see them in July. And, just because we see a school of gizzard shad in July doesn't mean we will see them in September. And, that two pound bass we see in March, most likely won't be two pounds in October.
Ponds become a living habitat where a pecking order develops based on the food chain, structure, cover, size class and age class of different fish. Add your management style, such as feeding, fertilizing or a sweet little blonde-headed girl handing off japanese beetles, and you get what you get. Since your pond has been thoughtfully stocked and is being well managed, I can't see gizzard shad becoming the dominant species. In Swingle's study, gizzard shad dominated because of that particular situation, in the beginning. Had he used the same stocking rate of bluegill and shad in the beginning, but had added 50 12" bass later, the results would have been completely different.
Besides, you are managing a half acre pond. If and when the shad become the dominant species (which I doubt they will do), they are not hard to eliminate. It is true that, once they reach a certain density, they stop reproducing. They also influence reproduction of other fish. When that density is reached, shad begin to deteriorate, and collect in dense schools, especially during cool months. They are easily harvested at that point.
Based on my experiences, I think what you are doing will render the shad just another fish in a well managed community of fishes.

PFF, I didn't check my water temperature before stocking the HSB but I did stock them at the same time a cold front moved through. I thought, as you, that cooler weather would be a better time. The farm I purchased the fish from were keeping the fish in a metal building and the water the fish were bagged in felt like the same temperature at the water in my pond so I did not float the bag. I have not observed any floaters.

Mr. Lusk, I appreciate your input and it makes me feel a little better about the situation. I was considering stocking the HSB and the discovery of the shad just helped the decision along. I plan to seine the pond in a month or so to give the school and now a new school broodstock for next years round of tilapia. This will be a good opportunity to survey the pond and get a better handle on the status of all the species.