Pond Boss Forums STOCKING A NEW POND Creating the food chain Clams for forage...

I am looking to diversify my food chain particularly for my RES. I am getting ready to add grass shrimp in a couple weeks. I was also pondering adding clams. I know RES love snails, which this pond already has plenty of native ones.

The first species of clam I was thinking of adding are the non-native Asian Clam, Corbicula fluminea. It is a golden color on the outside with some chipping that is white. It reaches a maximum size of about 1.5 inches and will do quite well in ponds, even clay and mud bottomed ones.

Now I would be more concerned about using a non-native species but this species is already quite common in the watershed this pond is in, so I will not be adding something somewhere it isn't already... Here is a Link about them for those not familiar with them.

I have heard RES love to eat them, particularly the smaller ones. My biggest concern is how they would affect the water quality? Remove too much phytoplankton and affect the zooplankton and reduce their numbers affecting the smaller sunfish which would be using this as a food source...

The second species would be the pond fingernail clam, Musculium securis. This is a native species, and as indicated in the common name is only attains a maximum size of about the size of a fingernail.

Collecting from wild sources, so that would be the method of stocking... Any thoughts on the matter?

I am very interested in this topic Travis. Benefits I can see are serving as additional forage for my RES and also potentially increasing visibility in ponds. I never thought about their impact on zoo or phytoplankton, however. I am looking forward to info here...

It may be worth a try, but if I was looking to fatten up res particularly, I would go with a sinking pellet. Mix some in with the floating feed and suspend a net or something near the bottom to catch the sinking ones. I have caught several res on surface flies and some in traps baited with fish feed late this winter/early spring. As a matter of fact, think I will try and find some. Luckily Rangens and Burris are near. Last I tried Rangen, it was too late in the year for them to be making it. They would have to crack a lot of clams to get much protein. Hey, we all like feisty, bloodthirsty redears(chinkypins).

I am trying to go the non feeding route. I don't have anything against it, but I like the idea of a natural food chain.

Im also interested in what everybody thinks,as Im thinking of adding them too.Its been discussed before,but I dont remember any decision of whether it was good or bad.

I think forage diversity is an important key to a healthy pond. Pay close attention to the little guys, and the big ones will thrive.

Having said that, we both know there are often unintended effects from adding or removing any species. For example, can clams be a parasite vector? As for phytoplankton depletion, I doubt that would be a problem unless your pond's bottom was densely covered with clams. If your water becomes too clear, you can always fertilize.

Interesting project CJ, and I hope you'll keep us posted.

Personally, I'd stay with native species. The Fingernails would provide forage for a greater portion of their life cycle than the
Asians due to their size at adulthood.

I thought that the protein content of clams was quite high? Not to mention the spinoffs of increased reproductive activity from the RES! Very interested to see what people have to say about this.

Here are a few threads to wade through on clams.

http://www.pondboss.com/forums/ubbthread...ite_id=1#import


http://www.pondboss.com/forums/ubbthread...=true#Post15148

http://www.pondboss.com/forums/ubbthreads.php?ubb=showflat&Number=136391&fpart=1

Here is what RES ate in Lake Pont. which includes clams. I can't extrapolate that to the question here however. Third col.

I have lots of freshwater mussels in my pond up to 4" long. No RES have been stocked, but maybe in the future since I also have crawfish. I think they improve my water quality and the pond stayed a nice healthy green tint all of last spring and summer. The racoons sure like them.

Good links Eric. I am particularly interested in how clams compete for and affect the plankton community in a pond. I like the Asian clam and fingernail clam because neither gets overly large like many of the native mussels do. Also, they do not have a parasitic stage. They are both well adapted to pond life and the mud/clay substrate that the majority of the pond they'll be going into is.

Eric

Do you think one would find water clarity increasing with the addition of fingernail or asiatic clams?

I am sure the clams are high protein, but a clam with shell the size of a fingernail cant have much meat in it. Can it? May be wrong. I would think small fish forage would be better, and mullosks just happen to be on the menu.

Dont see how they could effect the plankton base too much living on bottom, unless always in shallow water. Again, just thinking and talking. Dont know squat about the habits of pond snaila and clams.

Be very careful about adding Corbicula to ponds especialy if the pond has an overflow pipe or siphon. Corbicula is notorious for clogging intake structures and cooling towers. I am sure they will also clog out flow structures. Corbicula can in proper conditions become very abundant in small areas which would mean they would filter pond water to the point of negatively impacting the balance of the food chain. IMO addition of the native fingernail calms would be a much better addition to a pond's ecosystem than Corbicula - asian clams.
NOTE: species in the genus Corbicula are true clams and not mussels as in freshwater mussels. There are distinct morphological differences between clams and mussels.

Bill, that is why I mentioned them by name. They are very different than our native mussels and there was no information on them in Pond Boss that I could find. They are extremely abundant in the Potomac River watershed. I collect them, crack them and use them to fish for catfish and often catch other fish on them as well. My biggest concern is as you mentioned, them becoming overly abundant and over filtering the pond and impacting the balance of the food chain... If the pond has a high nutrient load from negative run off sources, could the clams be beneficial in keeping algal blooms etc under control?

I was doing more research of my own on the subject of clams as forage and in particular what do redears like to eat; when I came across an old post by Dr. Bruce titled: "Snails, Redears and Kingfishers" from 2004...



In it Cecil responded with:



From the above link, I read this, "Amos M. Gay and his new all-tackle world record redear sunfish (shellcracker) from Santee Cooper Diversional Canal, caught in August, 1998. The fish weighed 5 lbs. 7.5 ozs. and topped another fish from the same fishing hole by 3.5 ozs. The fishing hole where Gay caught this fish has produced at least three redear over 5 lbs. It is located where the canal meets Lake Moultrie. The area was intensively sprayed to remove vegetation, and the resulting bare bottom became the perfect home for an unnamed species of Asiatic shellfish. The shellfish are, of course, dinner for shellcrackers, and redear feeding in this area experience phenomenal growth and weight gain. If the shellfish are the infamous zebra mussels, redear appear to offer a perfect solution to control. Reduced zebra mussel expansion and big redear in one package!"

Further research found that it was not the zebra mussel the writer was referring to as they are not found in South Carolina nor are they of Asiatic origin, but rather the Asian clam, the species I mentioned in my original post. So it would appear Asian clams are a highly preferred food source for RES, allowing them to grow to record sizes.

Perhaps knowing the downsides to this species and keeping them in mind, stocking these clams may in fact be a way to grow very big RES! Bruce, perhaps if you are still looking for a food source for your RES, this may be it?

Bill, since Asian clams do not have byssus, do not attach to rocks or other materials but rather bury into sediments, unlike zebra mussels which do. How do they clog intake and or outflow pipes if they unable to attach themselves to such structures? I have kept them in aquariums and have actually had them reproduce in them and they never attach to anything, just stay buried in the sand and gravel.

Interesting topic. Unfortunately Bill, Eric, Burgermeister and others know a lot more about this than I do. I'm flattered that you overestimated me though CJBS2003.

Here you go CJ. There is more but will let you digest this first.



Use of the Asiatic Clam, Corbicula leana Prime,

in Toxicity Tests -The Progressive Fish-Culturist 1976;38:10–10

Ralph M. Burress and Jack H. Chandler Jr.,

Southeastern Fish Control Laboratory



C. leana is the most resistant of the bivalves we have

exposed to fishery chemicals and is more resistant than

most invertebrates. Any toxic substance applied to

water which kills C. leana might eliminate most other

invertebrates.

This exotic clam will probably continue to invade

and to thrive in other streams and may ultimately

crowd out indigenous mollusks -- especially where

water quality is deteriorating. C. leana has created

economic problems for industry by plugging water

lines, blocking valves, and contaminating gravel. Consequently

we encourage its use as a test organism, not

only because it is a highly satisfactory test animal but

also because such tests may lead to the discovery of a

chemical method for controlling its spread.



Modified Venturi Suction Sampler for Collecting

Asiatic Clams --The Progressive Fish-Culturist
Volume 41, Issue 3 (July 1979) pp. 121–123

Jack S. Mattice

Environmental Sciences Division, Oak Ridge National Laboratory

and

Wheldon Bosworth

The Asiatic clam, Corbicula sp., has been exl•anding

its range in the United States at a rapid rate since the

first record of its presence in 1938 (Burch 1944), and has

become a major fouling organism and a common

member of the freshwater benthic community in many

areas. The early emphasis on documenting the invasion

of the United States by this organism (Sinclair and Isom

1963; Dundee and Harman 1963; Britton and Murphy

1977) has shifted toward investigation of its life history,

distributional limits, population biology, and community

interactions. Because such studies generally require

accurate density estimates, adequate sampling

techniques that are useful in a variety of substrates

would be helpful. Density estimates of Corbicula have

previously been made by using a variety of gear types

and techniques, including the widely used Ekman (Fast

1971; Rinne 1974) or Peterson grabs (Sinclair and Ingram

1961; Lenat and Weiss 1973; Aldridge and Mc-

Mahon 1976), specialty gear such as that used for sampling

soft sediment bars in the Delta-Mendota canal (Prokopovich

1966), or by handpicking an area of bottom in

shallow water (Anon. 1976) or recently exposed by reservoir

drawdown (Rinne 1974). None of these sampling

techniques, however, is capable of quantitative

sampling over the full range of depths and substrate

types where Corbicula is found (Gardner et al. 1976),

and all are particularly poor at sampling rock and

gravel, gravel, or cobble substrates (Kajak 1971) where

the density of clams may be highest (Sinclair and Isom

1963; Clench and Stansbery 1969; O'Kane 1976).









Corbicula as a Biological Filter and Polyculture Organism in

Catfish Rearing Ponds --

The Progressive Fish-Culturist
Article: pp. 136–139

JOSEPH K. BUTTNER 1

Department of Zoology and

Fisheries Research Laboratory

Southern Illinois University



Abstract.--Corbiculafi uminea, an introducedA sian

clam, was stockedw ith channelc atfish( Ictalurusp unctatus)

in Illinois culture ponds. Survival of the stocked

clams was 36-79% over summer, but reproduction was

poor and the populationsd eclined.N everthelessp, onds

with Corbicula had less dissolved oxygen depletion, lower

turbidity,a nd greaterp rimaryp roductiont han ponds

without the clam. Growth of channel catfish was unaffectedb

y the presenceo r absenceo f clams.C orbicula

fiumineah asp otentialv aluea s a polycultureo rganism

and as a biological filter where water temperatures do

not exceed 30øC.

•

Corbicula fluminea (a clam introduced from

Asia) has been viewed commonly as a liability in

the United States (Sinclair and Isom 1963; Eng

1979). However, many of its features indicate potential

as a biological filter and polyculture organism.

Corbicula can survive, grow, and reproduce

in fish ponds (Buttner and Heidinger 1980; Buttner

1981; Buttner, in press). It is more tolerant of commonly

used aquaculture chemicals than most fishes

(Chandler and Marking 1979). Corbicula exhibits

high fecundity, has a prolonged period of

reproduction, and lacks the parasitic glochidia stage

characteristic ofunionids (Sinclair and Isom 1963;

Britton et al. 1979). Corbicula has a high filtration

rate (Buttner and Heidinger 1981), can effectively

harvest detritus, bacteria, and phytoplankton (Sinclair

and Isom 1963), and exhibits rapid growth

(Britton et al. 1979; Buttner and Heidinger 1980).

The soft tissue of Corbicula is approximately 45%

protein by dry weight (Haines 1979), and commercial

markets exist for the clam as fish bait, for

use in the aquarium trade, as food for domesti

cared animals, and for human consumption (Chen

1976; Sickel et al. 1981; Britton and Sickel 1982).

The potential of Corbicula as a biological filter

and polyculture organism was evaluated, and the

results are presented in this paper.

Methods

Combinations of clams and channel catfish (Ictalurus

punctatus) were evaluated in four 0.06-

hectare earthen ponds located in Jackson County,

Illinois, during 1977 and 1979. During both years

two test ponds received Corbicula and two control

ponds received no Corbicula; fingerling channel

catfish were stocked in all four ponds. In 1977,

clams of 10 to 42 mm shell length were stocked

in two ponds at 828 and 1,010 kg/hectare; in 1979,

clams were again stocked in the ponds at 1,222

and 1,717 kg/hectare. In April 1977, each of the

four ponds was stocked with 300 channel catfish

fingerlings averaging 49 g; in May 1979, each pond

again received 302 fingerlings averaging 60 g. In

both years, catfish were fed number 6 Purina Trout

Chow at 2% body weight daily, 6 d/week. Feeding

rates were adjusted weekly and all ponds received

equivalent quantities of feed. Dissolved oxygen,

net diurnal production, water temperature, pH,

turbidity, alkalinity, and nitrogenous wastes were

monitored; survival and reproductive success of

Corbicula were determined; and effect of Corbicula

on catfish survival, growth, and feed conversion

was examined (Buttner 1981; Buttner, in press).

Alkalinity averaged 84 mg/L and pH averaged 7.4.

Water temperature at dawn averaged 25øC (range

15-32øC) and at dusk averaged 28øC (range 18-

34øC); dissolved oxygen at dawn approximated

50% saturation and by late afternoon approached

or exceeded 100% saturation. Ponds were harvested

and drained in October 1977 and 1979.

Unless stated otherwise, all analyses were conducted

using the GLM package of the Statistical

Analysis System (Helwig and Council 1979).

Results and Discussion

Corbicula survived and reproduced in catfish

ponds, but recruitment was not sufficient to mainrain

stock density. Survival of stocked Corbicula

averaged 36% in 1977 and 79% in 1979. Reproductive

successo f Corbiculaw as indicated by the

presence of several larval clams less than 0.02 mm

in shell length, identified from 10 zooplankton collections

taken between August and October 1979.

Survival of larval Corbicula was poor and very

few young-of-the-yearc lamsw ere collecteda t harvest.

Adult Corbicula survived Karmex at 1 mg/L,

used to control aquatic vegetation; Batex at 0.25

mg/L, used to eliminate crayfish; and rotenone at

2 mg/L, used to kill contaminant fish.

No significant differences (P > 0.05) in survival

or growth of channel catfish were observed between

ponds with and without Corbicula, but •vater

quality was improved in ponds with Corbicula

(Table 1). Dissolved oxygen at dawn was greater,

incidence of dissolved oxygen below 3 mg/L was

lower, rate of primary production was higher, and

turbidity was lower in ponds with Corbicula. Nitrogenous

wastes were sometimes greater in ponds

with Corbicula. Trends were similar in both 1977

and 1979.

Habel (1970) and Busch (1974) observed that

Corbicula clams, stocked at 6,860 to 40,860 kg/

hectare in 0.0007-hectare pools, were associated

with decreasedt urbidity, increasedc hannel catfish

survival, and increased mean weight of catfish.

More recently, Haines (1979) observed that turbidity

of sewage effluent was lower in the presence

of Corbicula. However, as in the present study,

clam mortality was high and probably was related

to an intolerance to elevated temperatures and low

oxygen. Corbicula uptake of oxygen decreases

greatly between 25 and 30øC; at these temperatures

the rate of uptake at 70% oxygen saturation is half

that in waters at 100% saturation (Mattice and Dye

1979; McMahon 1979). Water temperatures in excess

of 33øC produce mortalities (McMahon and

Aidridge 1976).

Based on these observations, the greatest potential

of Corbicula as a biological filter and polyculture

organism would be in systems with cooler

temperatures and higher dissolved oxygen than

commonly found in channel catfish ponds. The

clam should be introduced only in waters where

temperatures rarely exceed 30øC and dissolved

oxygen is greater than 50% saturation. In such a

system, Corbicula could be stocked on the substratum

of earthen ponds or possibly in cages suspended

in slowly circulating water. Corbicula may

be useful in promotion of water quality in discharge

canals, after secondary treatment of sewage,

or in the effluent of fish raceways. Polyculture with

cool water fishes such as striped bass (Morone saxatilis),

walleye (Stizostedion vitreum), sauger (S.

canadense), and yellow perch (Perca fiavescens)

may be possible because optimum temperatures

for these species range from 22øC to 28øC (Hokansen

1977; Coutant and Carroll 1980). These

temperatures more closely approximate the optimal

temperature for Corbicula than does the optimal

temperature for channel catfish (30øC: NRC

1977). Prior to extensive use of Corbicula in polyculture

systems, its effect on nitrogenous wastes

should be identified.

Acknowledgments

I would like to acknowledget he assistancep rovided

by the Department of Zoology and the Fisheries

Research Laboratory, Southern Illinois University

at Carbondale. The study was supported,

in part, by a grant from Sigma Xi, the Scientific

Research Society.

References

Britton, J. C., D. R. Coldiron, L. P. Evans, Jr., C. Go*

lightly, K. D. O'Kane, and J. R. TenEych. 1979.

Reevaluation of the growth pattern in Corbiculafiuminea

(Miiller). Pages 177-192 in J. C. Britton, editor.

First international Corbicula symposium. Texas

Christian University, Fort Worth.

Britton, J. C., and J. B. Sickel. 1982. From the editor.

Corbicula Newsletter 7:2.

Busch, R.L. 1974. Asiatic clam, Corbicula manilensis

Philippi, as biological filters in channel catfish Ictalurus

punctatus (Rafinesque) cultures. Master's

thesis. Auburn University, Alabama.

Buttner, J. K. 1981. Asiatic clam in channel catfish

rearing ponds: its biology and its effect on water

quality. Doctoral dissertation. Southern Illinois

University, Carbondale.

Buttner, J. K. In press. Biology of Corbicula in catfish

rearing ponds. J. C. Britton, editor. Second international

Corbicula symposium. Little Rock, Arkansas.

Buttnet, J. K., and R. C. Heidinger. 1980. Seasonal

variations in growth of the Asiatic clam, Corbicula

fluminea, in a southern Illinois fish pond. Nautilus

94:8-10.

Butmet, J. K., and R. C. Heidinger. 1981. Filtration

rate of the Asiatic clam, Corbiculafiuminea. Transactions

of the Illinois State Academy of Science 74:

13-17.

Chandler, J. H., Jr., and L. L. Marking. 1979. Toxicity

of fishery chemicals to the Asiatic clam, Corbicula

fiuminea. Progressive Fish-Culturist 41:148-150.

Chen, T.P. 1976. Culture of the freshwater clam, Corbicula

fiuminea. Pages 107-110 in Aquacultural

practices in Taiwan. Page Brothers, Norwich, England.

Coutant, C. C., and D. S. Carroll. 1980. Temperatures

occupiedb y ten ultrasonic-taggeds triped bass in

freshwater lakes. Transactions of the American

Fisheries Society 109:195-202.

Eng, L.L. 1979. Population dynamics of the Asiatic

clam, Corbiculafiuminea (Miiller), in the concretelined

Delta-Mendota canal of central California.

Pages 40-68 in J. C. Britton, editor. Proceedings

first international Corbicula symposium. Texas

Christian University, Fort Worth.

Habel, M.L. 1970. Oxygenc oncentrationt, emperature

tolerance, and filtration rate of the introduced Asiatic

clam Corbicula manilensis from the Tennessee

River. Master's thesis. Auburn University, Alabama.

Haines,K .C. 1979. The useo f Corbiculaa sa clarifying

agenti n experimentalt ertiary sewagetr eatmentp rocess

on St. Croix, U.S. Virgin Islands. Pages 165-

176 in J. C. Britton, editor. Proceedings first international

Corbicula symposium. Texas Christian

University, Fort Worth.

Helwig, J. T., and K. A. Council. 1979. SAS user's

guide. SAS (Statistical Analysis System) Institute,

Raleigh, North Carolina.

Hokanson, K. E.F. 1977. Temperature requirements

of some percids and adaptations to the seasonal temperature

cycle. Journal of the Fisheries Research

Board of Canada 34:1524-1550.

Mattice, J. S., and C. C. Dye. 1976. Thermal tolerance

of the adult Asiatic clam. Corbicula Newsletter 2: 8.

McMahon, R. F. 1979. Response to temperature and

hypoxia in the oxygen consumption of the introduced

Asiatic freshwater clam Corbicula fiuminea

(Miiller). Comparative Biochemistry and Physiology

A, Comparative Physiology 63:383-388.

McMahon, R. F., and D. W. Aidridge. 1976. Respiratory

responsesto temperature and low oxygent ension

in Corbicula manilensis, Philippi. Corbicula

Newsletter 1:6.

NRC (National Research Council). 1977. Nutrient requirements

of warmwater fishes. NRC, Subcommittee

on Warmwater Fishes, National Academy of

SciencesW, ashington,D .C.

Good stuff Eric... I have found them anywhere from sandy gravel bars in the brackish areas of the Potomac River, to silt bottomed reservoir shores to muddy pond shores, so they are quite adaptable. I think they may be a good addition to ponds where people are feeding there fish as well...

CJBS - The first article provided by Eric stated "C. leana has created economic problems for industry by plugging water lines, blocking valves, and contaminating gravel." C. leana is not C. flumenia but a very similar species in the same genus. I'm not sure of the mechanism that the clam uses to grow in pipe or wet areas but I do know that the Duquesne Light Co in Shippingport PA annually removed them by the dump truck loads from their cooling towers.

My real or main fear for them in a pond is for them to become overly abundant and decimate the food chain due to overfiltering the water. It is also a possibility that the concentrated hight fertility from their manure deposits due to very high numbers could cause nuisance algae blooms. I would want to first try them in small easily drainable ponds before turning them lose into a larger pond. Also use of them as an exotic speices outside their current geographical range would cause undue problems in local water sheds. Nature has many ways of distributing its creatures.

I would definitely not use them in areas where they are not already introduced which isn't an issue for me since they are already found commonly in the Potomac River drainage. I am still curious how they clog things up without byssus. I think I may add them to a smaller pond and see what they do. I think their value as RES food is worth the effort.

My concern was not so much with you and your location but with others wanting and using them outside the clams current distribution range. I think what happens is the clam is able to establish itself in a crack or crevice and the population somehow builds on itself and increases. I'm not sure of the specific physical development but evidently it does occur. I've lost contact with my co-workers that worked directly with the Corbicula at the DL Power Plant so I cannot right now provide any more than what Eric noted above.

I'll look into it more before I make a final decision. The last anyone wants are a bunch of clams clogging their pipes up. I definitely don't want anyone introducing the clams where they aren't already found...

Isnt the idea that the RES will forage on them enough to keep the numbers down? If they are catching 5#+ redears where they are abundant, the redears must be hitting them pretty hard. Maybe finding more about their reproductive potential would be worthwhile.

Yeah, I think if you have a pond with a healthy RES population, they will keep the clam numbers down.

My plans right now for the 1/3 acre pond are 100 RES of both sexes, 20 male BG, 10 SMB stocked per year, as I doubt there will be any natural reproduction(all mud/clay bottom), and 5 HSB per year along with my special potion of forage fish. My goal is to grow some huge RES and some decent sized BG along with the occasional nice SMB and HSB. So hopefully the only fish naturally reproducing will be the RES and forage fish.

What kind of special potion are you going to use? They will be the key to the entire "cycle". The Res won't produce enough offspring to influence anything and the occasional decent SMB and/or HSB will be hard to come by without 4 to 6 inch groceries.

Absolute gender identification of BG would be a slippery slope for me. They would have to be larger for a positive ID and even then....

I would be VERY cautious about purposely adding any kind of snail, clam or other mollusk. I don't want to stock anything that attaches itself as a parasitic fluke to a fish. Caution: What I don't know about RES would fill a much larger book than what I do know. Likewise on clams and snails.

Do redears actually NEED things with shells or will/can they thrive on a fish diet alone? I see snails and other hard backed thingies as something that redears can help control but not really need as part of their daily bread. Give me some help here.

I see the addition of mollusk type life forms as a potential for harm to the well being of the entire fish population. Elimination of them can be pretty questionable if it doesn't work.

If it is an experiment and you acknowledge the present and future potential for damage to the pond and all area ponds then have at it. I don't believe that birds introduce fish but do know that they introduce parasites to area water holes.

The Asian clam I am considering adding does not have a larval stage that attaches itself to fish like our native mussels do. So that is not a worry of mine. I realize the risk and if the clams do something haywire, well life will go on. Many of the ponds and lakes around here have them already and they are doing just fine.

The pond already has two species of snail, which I am sure the RES will enjoy once they are stocked. I am sure RES will eat zooplankton, other larger invertebrates such as the grass shrimp I am stocking next month and to an extent small forage fish. Without heavy BG competition, they may use more of the "softer" food sources.

I am very familiar with BG and how to sex them. I have a source of healthy adult fish to select from.

Last year I stocked bluntnose minnows, golden, spotfin, satinfin and spottail shiners, banded killifish, tessellated darters, eastern mudminnows and creek chubsuckers.

This year as I source more of the above I hope to add them. I also am trying source some inland silversides and if Overton's has a good spawn, in the next year or so I hope to obtain some lake chubsuckers to work with.

I am sure a few of these forage fish won't take hold or will be eaten to extirpation once the predators are added, but with all of last year to spawn and all of this year to spawn I think I am giving them a good chance. The RES maybe added this year, but I am thinking of holding off until next year to add them to give the grass shrimp a full year to get established and if I do go with the clams the same deal...

The low numbers of non reproducing SMB and HSB shouldn't pressure my forage nearly as much as numerous juvenile SMB being born every year.

My biggest concern is if my RES and BG hybridize and then cross back to produce female BG. That and the darn otter I have been seeing lately!

In the end this pond is a giant forage base experiment to "practice" with for a future larger more diverse pond.

I'm not familiar with any of your forage concoction. How large do they get? I'm referring to the suitability of proper sized forage for the SMB and HSB.

You should gone to Medical school. That way you could consider everything you do as practice.

Sounds like an interesting experiment and lots of fun.

All are roughly the same size as FHM, maybe an inch or two larger so maybe 5" tops. Except for of course the golden shiners and the creek chubsuckers which are about the same size maxing out around 10-12".

I think RES do just fine without mollusks as long as other slow-moving and bottom-dwelling forage is plentiful. If their preferred mollusks and insect larvae are scarce, the downward gazing eyes of the RES may put them at a disadvantage. That's just an educated guess.

Bill, from the Global Invasive Species Database:

Ecologically, C. fluminea can outcompete many native clam species for food and space (PNNL 2003). The introduction of C. fluminea into the United States has resulted in the clogging of water intake pipes, affecting power, water, and other industries. Nuclear service water systems (for fire protection) are very vulnerable, jeopardising fire protection. In 1980, the costs of correcting this problem were estimated at 1 billion dollars annually. C. fluminea causes these problems because juveniles are weak-swimmers, and consequently they are pushed to the bottom of the water column where intake pipes are usually placed. They are pulled inside the intakes, where they attach, breed, and die. The intake pipe become clogged with live clams, empty shells, and dead body tissues. Buoyant, dead clams can also clog intake screens.

Would this relate to pipes used in water level management systems people use in their ponds?

Also, from the Global Invasive Species Database:

C. fluminea is found in lakes and streams of all sizes with silt, mud, sand, and gravel substrate (INHS 1996). They can tolerate salinities of up to 13 ppt for short periods (Aguirre and Poss 1999) and temperatures between 2 and 30 degrees Celsius, or 86 degrees Fahrenheit, (Balcom 1994). It prefers fine, clean sand, clay, and coarse sand substrates (Aguirre and Poss 1999). It is usually found in moving water because it requires high levels of dissolved oxygen. C. fluminea is generally intolerant of pollution.

It mentions how it usually found in moving water because it requires high levels of DO. I have also found them in several small reservoirs. Might this requirement of high DO, help keep the population in check or perhaps preclude it from establishment in the pond I am thinking about adding them to?

Now we know a little more of the story. Thanks for finding that bit of info. I forgot about these clams floating when dead. Limiting disolved oxygen conditions of the sediments will depend primarily on the tolerance levels of the species and condition or features of the sediments. Water depth and pond morpology will also have an influnce. Numerous variables. Any info on that lower DO tolerance topic available? Surface or subsurface sediments often have DO levels droping to 0-1ppm - depending.

Presence of weak swimming juveniles could result in them colonizing pond intake structures depending more variables.

It's all the more info I could dig up, and I have been digging! I will have to take a picture of the overflow pipe this pond has, but I don't think these clams could cause an issue with it. I think I will add the clams. Either they will not take hold because of low DO issues, they will flourish a little too much and make a mess, or they will help grow some huge RES. Won't know til I try it...

I would like to see some data or studies for RES stocked with Corbicula. IMO Corbicula have too thick of shell for optimum foraging by RES. IMO a thin shelled snail would be better in several ways or just as good a Corbicula. Many individuals of Corbicula in a mixed population are too large (0.5"-1.2") for consumption by RES.

I can't find any studies. Just anecdotal evidence, such as the two world record RES were caught out of Santee Cooper a few years after the clams found there way in there and many local fisherman said it was the clams that caused the boom in RES sizes. My pond will no doubt me an experiment. If I see good results maybe I can catch a few and see if we can't do a food study on them...

"Boom" in RES sizes if true and due to Corbicula, then IMO it was due to the new or initial colonization population growth phase of Corbicula which resulted in a very high percentage or proportion of small individuals for a few years. Once the population stabilized and a big percentage of the population became adults the numbers (%) of small sized calms droped dramatically and growth of RES leveled out and is now probably back to normal growth rates.

That might be the case... I guess I'll find out as I am gonna give it a go.

They didn't actually come out of Santee Cooper did they? I thought it was a channel between Sante Cooper and another body of water.

CJ:

With the negetatives that are being brought to light about the Corbicula fluminea, what makes them a better choice over the native fingernail clam? I'm probably missing something here, but in my mind, the fingernail will still be a food source even at the adult stage, where the Asian will be too large.

What did I miss??

Cecil, it was a navigation channel as I recall...

I am not sure I can find a source for the native fingernail clam. I am definitely going to give it a hard look this year... If anyone has fingernail clams in there pond, let me know and send them my way! I have seen them before in the area, just a matter of finding them again and collecting them. The Asian clam is all over the place, no problem finding it...