Interactions between Walleyes and Four Fish Species with Implications for Walleye Stocking
ANDREW H. FAYRAM, MICHAEL J. HANSEN, TIMOTHY J. EHLINGER
The last two trips out after bass have resulted in a pair of walleyes being caught. This got me looking into more walleye studies related to the pair of fish in question. As I posted a couple weeks back in another study, the evidence suggested that largemouth and walleye don't overlap in diet in many bodies of water. This newer study suggests they simply might not be able to get along together at all. This might be why it seems like it is so tough for IDNR to establish a good walleye fishery in most of our reservoirs. The study in this post from 2005 provides a perfect example of this.
Researchers used a number of different data sets and four criteria to evaluate evidence of competition and predation between walleye, pike, muskie, smallmouth bass, and largemouth bass in northern Wisconsin lakes. Only largemouth bass were found to strongly interact with walleyes:
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Largemouth bass and walleye populations were inversely related - so if you had a high population of established bass, you would end up with a low population of walleye.
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Diets of largemouth bass included juvenile walleyes - It was estimated that as many as 80,000+ juvenile walleye were consumed by bass yearly, and that walleye made up about 5% of the basses diet. On the other hand, it was very rare to find an adult walleye that had fed on any bass.
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Walleye growth was positively related to largemouth bass abundance - Since more bass equaled less walleye, the remaining walleye that did survive exhibited good growth due to lack of competition for food resources with other walleye.
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Largemouth bass abundance increased as walleye stocking intensity increased, and survival of stocked walleyes was negatively related to largemouth bass abundance - It seemed like the more walleye that were stocked, the larger the bass population got. The theory extended was that the extra stockings of walleye became and additional (previously unhad) food source for the bass population allowing it to expand with the increase in food options. Likewise, the larger the bass population, the less the likelihood of stocked walleye survival.
There are other possible explanations for some of the findings, such as the type of waters that support good largemouth bass populations may be different enough from a morphological standpoint that they become poor environments for walleye survival and populations. Still, the research findings in this paper match nicely with several other studies that suggest the exact same inverse relationship between the two fish species. The researchers even went so far as to conclude,
"Given the seemingly strong predatory interaction between walleyes and largemouth bass, management of both species in the same water body may be difficult. In addition, walleye stocking may be ill advised in lakes with even moderate abundances of largemouth bass, given their potentially large impact on survival of juvenile walleyes."
I'll further look into more walleye research since IDNR continues to stock many of our impoundments with walleyes. I might even spend more time fishing for them next year as a change of pace. Haven't decided exactly what my fishing goals are yet for 2012. Still, I've gone ahead and added a new category (Walleye/Sauger/Saugeye) on the lefthand sidebar of the site and have added this file type to all older posts I've come across related to walleye for those that might be interested.
Brian,
Just out of curiosity, have they considered stocking saugeyes instead of walleyes? I realize that a self sustaining population would be a better solution. But, if bass eat too many of the walleyes for the population to sustain itself properly, why not go with a put and take fishery? Our local lakes over here in Ohio seem to be doing pretty well with a mixture of bass and the put and take saugeyes that the ODNR stocks.
Of course, I haven't seen any studies of the interaction between the species locally. If you have seen anything from the ODNR on the subject, I wouldn't mind hearing about it.
Joe
Posted by: Joe Vanfossen | December 21, 2011 at 12:54 AM
Joe - Our state does stock saugeyes in 2 or 3 reservoirs, and have conducted their own research which shows better survival and contrbution to harvest of saugeyes over walleye. That said, I believe a couple factors come into play. One, we can create our own supply of walleye, but I believe we have to purchase/trade for saugeye fingerlings to stock. I think that limits stocking them in Indiana to some degree. Second, studies show that saugeyes can backcross easily with either parent stock material (walleyes or sauger), and subsequent original genetic degradation has become a hot topic, to the point that some states are considering halting or limiting their saugeye stocking programs. So I believe saugeye are only stocked where there is a minimal likelihood of backcrossing with any natural/established populations of either parent here.
As to competition between bass and saugeye:
Factors influencing saugeye stocking success in Ohio reservoirs
Christopher Robert Aman
Abstract: In Ohio reservoirs, abundant gizzard shad support a successful saugeye stocking program. To explore the ability of a robust gizzard shad population to support high density saugeye populations and evaluate factors that might limit stocking success, we stocked saugeye into Acton Lake at densities of 3,260 fingerlings per hectare, 8 times typical stocking rates. High- density stocking over 2 years failed to produce a saugeye population with abundances greater than those reservoirs stocked at the usual rate of 413 fingerlings per hectare. Annual survival of saugeye ranged 0.25% (2004) - 0.32% (2005), far below rates documented historically in Ohio reservoirs. To explain low survival, we considered emigration, saugeye distribution, prey abundance, and predator impact. Emigration was an unlikely explanation because Acton spillway discharge varied markedly between 2004 and 2005 while saugeye survival did not. Overall gizzard shad availability clearly did not limit saugeye consumption, though prey availability may have influenced predation by other piscivores. Diet data from these piscivores could not account for saugeye loss, though rapid digestion of saugeye relative to larger prey could cause us to underestimate saugeye presence in age-i saugeye and largemouth bass Micropterus salmoides diets. Whereas hypothetically increasing the number of saugeye recovered from age-i saugeye diets could not account for a large proportion of potential age-U saugeye production, hypothetically increasing the number of saugeye recovered from largemouth bass from 1 to 4 could account for much of the observed saugeye mortality. Predation by white crappie also may have contributed to poor saugeye survival. Potentially intense largemouth bass predation on saugeye was driven by an extremely dense largemouth bass population, and may have been driven by an absence of buffering juvenile gizzard shad immediately post stocking. Predation on saugeye likely was influenced further by a range of environmental variables, including light penetration and available habitat. Rearing saugeye to a size >31 mm or delaying stocking until age-0 gizzard shad become available to buffer predation could potentially mitigate interactions between largemouth bass and saugeye. Because largemouth bass and possibly white crappie predation likely limited saugeye survival in Acton Lake, density of these predators should be considered in any percid stocking program.
Posted by: Big Indiana Bass | December 21, 2011 at 09:55 AM
I never realized this phenomenon before. It is strange how smallmouth bass and walleye can very easily flourish the same body of water but largemouth bass and walleye cannot.
Posted by: Lake Erie Walleye Fishing Charters | January 23, 2012 at 01:38 AM