Mortality Rate

Does Any One Have Info On The Mortality Rate On The Flathead Catfish, And Does The Waters That They Swim Play A Major Role In There Reproduction.

I have a really good article in one of my in-fisherman magazines about that Mike if I can find (if it made it to GA) I will retype the article for ya on the site

cool thanks buddy, i know that the Minnesota river is a real good flathead river but was just wonder how much lets say silt verse sand have a role play in the reproduction and the hatching of the eggs. one thing that the Minnesota river has a lot of is inlets and most of them are of sand and gravel, now the bad part of that is most of that water comes from farm fields and such. ok before this gets out of hand some were they are doing a lot of work to control the amount of such water reaching the river and are doing vary well with this, but we are still finding 3 legged frogs and such things like that. im sure if you can't find it buddy someone will eventually chime in some were.

Well Mike I woke up and thumbed through a lot of the issues I thought it may be in and I cant find it Im gonna go and search the in-fisherman site and see exactly which issue its in if I can

Mike
I have lots of technical data from game departments and Doctorate thesis.

I am not sure if you are looking for information on total population mortality such as populations dynamics and age class pyramids or young of the year mortality.

Population dynamics will differ from waterway to waterway due to habitat.

Young of the year mortality changes with habitat but most large year classes are primarily due to water clarity after spawn. Flooding causes muddy water which is a catfishes best defense as a fry/fingerling.

I have several different studies (somewhere) on both mortality figues but each is confined to the particular waterway sampled.

I Am Was Wonder More On The (Young Of The Year Mortality), And That Is Basically Do To A Few Reasons In My Area In Minnesota That I Fish On The Minnesota River (North Of New Ulm Minnesota). Any Info Would Be Just Fine It Don't Have To Be For Just Minnesota I Think.

Quote :

Age, growth, and mortality of introduced flathead catfish in atlantic rivers and a review of other populations.

KWAK Thomas J. ; PINE William E. ; WATERS D. Scott ;

Quote :

The annual total mortality rate was similar among the three rivers, ranging from 0.16 to 0.20. These mortality estimates are considerably lower than those from the Missouri and Mississippi rivers, suggesting relatively low fishing mortality for these introduced populations

This quote is from NC studies of flathead populations introduced into
non native waters. The study is still in progress but several other
technical papers will be published.

Quote :

Mortality
Mortality estimates derived from catch curves were
relatively consistent among rivers (Table 4). Instantaneous
total mortality rates ranged from 0.17 to 0.22,
and annual total mortality rates ranged from 0.16 to
0.20 (i.e., 16–20%). Low catch rates of older fish (ages
8 and older) and variation among cohorts decreased the
precision of our mortality estimates, and 95% confidence
intervals averaged +/-60% of the associated Z
estimates. We detected no significant difference in Z
among populations by analysis of covariance (F2,20 ¼
1.23, P ¼ 0.29), and 95% confidence intervals for all
estimates overlapped the means of the other two
estimates.

Definition of decreased pecision and plus or minus 60% is that
they did not capture enough older fish (none over age during
the study to predict figures with any probability of more than 40%
accuracy. The 3 waters sampled included 36-94-114 flathead.
Clearly not enough of the population to determine anything
without those mathmatics projections that the authors concede
may not be accurate.


Sample sized fish start at 128-200mm fish (5-8 inches). Only
about 1 of 800 flathead get to be 5 inch. Their estimation that
flathead mortality is lower due to recent introduction does
hold creedence. Quinns Flint river stomach samples
showed evidence of severe canibalism of young flathead. If
no older class predators (flathead) were available mortality rates
would be lower in these rivers.


I have somehow misplaced all the catfish studies directed by Steve
Quinn in Georgia. Those have much larger sampling of flathead
and would be better indicators of true mortality.

Quote :

Population Abundance and Stock Characteristics of Flathead
Catfish in the Lower St. Joseph River, Michigan
DANIEL J. DAUGHERTY AND TRENT M. SUTTON*

This chart is from the survey of flathead catfish on the St.Joseph River in Michigan. With almost 1200 flathead it gives a clear picture of the population pyramid and mortality rate of flathead over 4 inches.All age class fish are in the sample. Age determination was pectoral fin samples and accuracy is questionable for this method.I believe the low number of fish 4-8 inches is due to capture method instead of actual population. The rest of the numbers look normal.
Less than 5% of sampled fish were over 3 years old.

Quote :

Survival rates for flathead catfish have not been
quantified in lotic systems because of the limited
data availability and an overreliance on length- and
age-frequency distributions to qualitatively describe
fish survival. For example, Stauffer et al.
(1996) attempted to estimate survival and mortality
rates for flathead catfish and found that the
number of captured fish from each age-class did
not decline with increasing age. As a result, these
authors concluded that flathead catfish survival
was high. Although estimates of flathead catfish
survival are not available, the annual survival of
fish in the lower St. Joseph River (67%) was in
agreement with estimates for lightly exploited
populations of channel catfish.

This statement does not agree with data on the charts. Even if the author meant 2/3 of the previous year class survive the chart would be a downward angle instead of a big drop from 3 to 4 years and a pretty flat line.

Thanks for that great info Robby, I had no clue that there was such a high mortality rate from them eating there own young, and in the area here were i fish there is also tons of walleye that i have heard also eat walleye fry so that don't help with the population any at all. i don't know the bass population in that area because i don't fish for them, but i have heard that bass love to eat bullhead fry so im sure that they would also eat catfish fry the same. thanks again Robby that is some great info.

Actually observations of fish (bass) feeding on catfish concluded
that if the small catfish get their spines expanded the bass blew
the catfish back out. This makes sense because the injury would
not outweigh the benefits of a meal. It also supports catmens
view of clipping off bulhead spines before using them for bait.

This would be true for channel cats and bullhead that have bony
spines. Flathead have cartilage that folds down so they would
never get expelled. If fish are smart enough to learn the difference
and distinguish the species then it would follow that flathead fry
would be targetted and also eaten at a larger size. Predation
would be much greater.

There is not much we can do to influence predation of young catfish
but we may be helpful by practicing selective harvest especially
releasing larger catfish that produce larger amounts of eggs that
are normally more viable and better protected than eggs from smaller fish.

That is interesting.

ACE I Really Like To Read What Robby Rights About The Catfish, He Has Put Alot Of Work Into Knowing What These Fish Are All About. Great Info Robby.

Great info ....Thanks for sharing it with us...