Thx for data. Put them on the plot and added the YP curve back. I need to find SMB data in a paper. But should be between HSB & LMB.
Our data seems to put YP down with HSB, not above LMB where BSU paper put em. The shape is more HSBish.
Really makes me wonder about the overall shift between our data and papers. Nobody called me on private vs public water, but that seems a poor theory. Could be genetics or measurement technique?? Discussion welcomed!
This is a bad sign.. a Willis PhD student allowed to not use SMB gape but instead peacock cichlid. If Willis didn't know of any SMB gape data, how am I going to find it? I'll try to get my hands on the Hill paper and see what it says, and then add the cichla curve.. later today.. tis Easter with a beautiful sunrise and wife's Bday at same time.. I am fixing the dinner.
I estimated smallmouth bass GW using published equations for peacock cichlids Cichla ocellaris (Hill et al. 2004
PS.. a 20" cichlid/SMB with 2.3" vs a LMB at 2.5 while HSB at 1.5".. anyone believe that?
PPS: Willis let a PhD student pull one over on him. The Hill paper does not say SMB=cichlid, it says LMB=cichlid. And that explains the 20" data.
Given the morphological similarity of largemouth bass and peacock cichlids, we predicted that a simple method of estimating gape size used for largemouth bass (i.e., external mouth width; Lawrence 1958, Hambright 1991, Johnson and Post 1996) would also estimate peacock cichlid gape size
Last edited by DNickolaus; 04/20/1407:32 AM. Reason: Hill paper quote
You should be able to get all the mouth gape data that you need from the numerous members here that have SMB in their ponds. Some including Bobby Rice go SMB fishing on summer vacation. Lets encourage all of them to take some measurements of SMB they catch this summer. One just has to not be in a hurry for the data.
aka Pond Doctor & Dr. Perca Read Pond Boss Magazine - America's Journal of Pond Management
Where did you get the mouth gape data for YP? I don't think their mouth size is greater than LMB at least the way I measure mouth gape. Here are some of my measurements of horizontal mouth width for yellow perch: 3"=0.27", 5"=0.59", 6"=0.70", 7"=0.86", 8"=0.94", 9.0"=1.08", 10.0"= 1.10", 11"=1.18". 12"=1.3".
Last edited by Bill Cody; 04/21/1408:08 PM.
aka Pond Doctor & Dr. Perca Read Pond Boss Magazine - America's Journal of Pond Management
Thanks for your additional data Bill. I'll add it.
My source is clearly cited for the YP curves- it's from Ball State. And the discussion points out concern. I'll attempt to reach authors.
The beginning of my graduate research was a good literature study. All advanced research should benefit from prior work and sift what is valuable. As you say, we need not be in a hurry and I believe that includes not hurrying to dismiss unexplained data. We may learn valuable things.
I'm pasting in the emails with Prof Tom Lauer at Ball State. You all can judge for yourselves.
The student author is now a fisheries biologist in Oregon, but she is out on medical leave after she broke her back in a helicopter crash doing a fish survey. I left a msg with her husband in the same office. I am removing the YP curves for now.
Dan I haven’t measured the largemouth bass gape and couldn’t tell you how yellow perch relates. From your comments, you appear to be questioning our yellow perch measurements. Fair enough. Measuring a few hundred yellow perch and largemouth bass of the same size would provide you with your answer. Tom Lauer
Thomas E. Lauer, PhD George and Frances Ball Distinguished Professor of Biology Director, Aquatic Biology and Fisheries Center Department of Biology Ball State University Muncie, IN 47306 TX: 765-285-8825 Fax: 765-285-8804 Email: tlauer@bsu.edu
From: Nickolaus Sent: Monday, April 21, 2014 8:43 AM To: Lauer, Thomas Subject: RE: Yellow Perch gape
Prof Lauer, Below is a screenshot of the table upon which I based the plot. Yes, many say that gape is a theoretical maximum prey dimension. I seek the physical dimension of the YP gape, and am not considering prey size. The paper seems to say GHM is a perch gape measurement, but these equations indicate a YP gape larger than that of a LMB when compared to other literature. Dan
Dan You plotted the theoretical maximum of the prey species, not the actual ingested prey size. In general, most piscivores will consume prey up to 1/3 to ½ their length. The portion of figure 3 that you did not graph is the actual consumption size. I suspect when you eat, you could take a bigger bite. I also suspect you rarely, if ever, take a bite that fills your entire mouth (the theoretical maximum). Tom Lauer
Thomas E. Lauer, PhD George and Frances Ball Distinguished Professor of Biology Director, Aquatic Biology and Fisheries Center Department of Biology Ball State University Muncie, IN 47306 TX: 765-285-8825 Fax: 765-285-8804 Email: tlauer@bsu.edu
From: Nickolaus Sent: Monday, April 21, 2014 7:33 AM To: Lauer, Thomas Subject: Yellow Perch gape
Good morning sir. As the father of a BSU freshman, I was pleased to see a BSU paper on a topic I’ve been researching, namely piscivore horizontal gape. I own a pond South of Lake Monroe and have been gaining understanding in developing a stable ecosystem. I’ve gotten involved in a forum called Pond Boss that discusses pond management. I’ve been trying to catalog the gape data for different pond fish, both from academic papers and Pond Boss member measurements. I have found it very interesting but your data from Gape limitation and piscine prey size-selection by yellow perch in the extreme southern area of Lake Michigan, with emphasis on two exotic prey items, Table III has me puzzled. For the sake of discussion, I’ll add my current literature search plot. I did the calculations in mm and converted to inches- but you can see that YP end up above largemouth bass. We all know that isn’t the case, so I thought to seek your input on how I might have interpreted your paper incorrectly. I would expect YP to be around 9-10% GW/LT. If I could reach enlightenment on this quandary and find some smallmouth data, I’d be pleased.
I've got a start on the YP measurements. Hopefully some other Pond Bossers can help fill in more data. I'll take measurements of LMB in my pond as the season progresses. We had a cold front roll through the area this afternoon, high winds, 10-15 degree temp drop and lightening. I suspect the fish will be harder to catch for the next few days. I'll report more fish as the data is available.
will be happy to toss in any and all data that floats by. Once we get a reasonable sample for a species, I can do a linear fit and we can generalize relative gape sizes. That point for the 18" Cody LMB is gonna be an outlying point for any linear fit I fear. Reminds me of a few catfish I could put whole hands in.
Symbols are our measurements. The lines are from literature.
Dan - that the outlying gape for the 18" LMB was a calculated measurement and not an actual measurement. WE need some members to catch 17", 18" and 19" LMB and get some actual measurements.
aka Pond Doctor & Dr. Perca Read Pond Boss Magazine - America's Journal of Pond Management
Dan - In rechecking my data, I notice that the outlying gape for the 18" LMB was a calculated measurement and not an actual measurement. We need some members to catch 17", 18" and 19" LMB and get some actual measurements and replace my outlying gape estimate datum point.
It is good that Dr. Tom Lauer at Ball State responded to your inquiry.
Last edited by Bill Cody; 04/21/1408:10 PM.
aka Pond Doctor & Dr. Perca Read Pond Boss Magazine - America's Journal of Pond Management
I have those size LMB swimming in my pond. But, the mouth gape will be skewed to the small size because most of them should be pellet trained. We need to get the Texas boys in on this thread!
I will remove that LMB point. It stood out as odd. Thank you for filling us in on that one.
Does gape actually change with environment then? Would have figured it's more genetic then environment. Why would eating pellets reduce mouth/bone growth? Eating full-bite prey stretches it somehow? (Another interesting area of research I've seen in the literature.. why do they eat maximum gape prey? .. seems an energy efficiency thing)
We seem biased to higher mouth sizes than the literature. I'd be happy to see some data on the smaller side.
It was good of Lauer to respond. I didn't feel he answered my question though. Data has to pass a gut-check and should fit into a continuum. It doesn't exist in isolation. When things don't make sense, it is a good thing to probe for explanations.
Eating pellets allow the fish to grow faster, and it seems that the head doesn't grow as fast. The pellet trained LMB in my pond have big bodies, but small heads. The offspring that are in the pond that aren't eating pellets are more porportional.
I talked to highflyer last night. He's going to collect data on LMB during his get together this Sat and post the numbers. I don't think a lot of the LMB in his pond are pellet trained, but there should be ample live forage for them. He said his WR's were running 120-140.
I don't think plasticity of gape size will be very high in one generation. In addition all of the pellet trained LMB in ponds I am aware of have natural forage so they don't rely on pellets alone. interesting idea to investigate.
Would be great to get a slug of data from the Tx Big Do. One could never say for certain that a fish was wholly pellet fed unless you have a single-species pond that is a strict piscivore (upon adulthood), so I don't know how we could try to categorize our data to determine effect of feed/growth.
Would be an interesting MS thesis to do a controlled experiment to determine the effect of feeding & growth rate on relative proportions. But it would be a multi-year effort.
To be fair with the concept, does this not open the opposite possibility that the YP data is correct? If those YP are exceptionally slow-growing in Lake Michigan, no pellet feed, cold winters, short growing season, poor prey source, then would it not follow that for the body length they would have relatively large gapes?
I'm not sure about YP. With the YP that I've caught, I haven't seen the size difference between feed trained/non-feed trained like I do with the LMB. Why that is, I have no idea.
I have a LMB only pond and I plan on doing some sampling in a few weeks. They have had nothing but pellets since I stocked them except for a few tadpoles. 300 were stoked in July of 2012. They were 2" at that time.
We should be able to get lots of mouth gape data from numerous willing members here. Data from various locations will result in more validity to the data. When I measure mouth gape for a bass I hold it by the lip and measure the distance across the inside of the mouth. Basically what will fit into the mouth without stretching it side to side.
Last edited by Bill Cody; 04/22/1408:07 PM.
aka Pond Doctor & Dr. Perca Read Pond Boss Magazine - America's Journal of Pond Management
I found this blue gill today when feeding the fish. It looks to have been hit by an LMB. The bite radius looks to be about 5 inches. How long would the bass be? Best guess
Extrapolating from our few measured points, you need a 29" LMB to get a 5" wide gape. The literature only has that length fish at 4" gape. Extrapolating the AL LMB growth curves, you'd get a 12-15 year old fish. The FL curve says 15 yo or so. Per literature, LMB have lived that long, but not the norm. Northern states couldn't get one that long on avg.