...I have crawfish all over my pasture, so I assume that when the pond does fill up, I'll have a fairly healthy crawfish population...
I'm not crawdad expert, but I think the ones in your pasture will likely stay in the pasture. Are they the ones that make mud "chimneys"? Those types don't typically want to live in pond waters. I think they call them Land Lobsters. Check it out anyhow...I'd hate for you to get your hopes up. You may have to stock some water loving variety native to your area.
JPS, Are there rule-of-thumb charts for carrying capacities/standing weights? (I'm still unsure of the difference...standing wt = current pounds per acre? carrying cap = a standing weight at which a fish kill is near given current conditions?).
If only it were that simple. What determines carrying capacity is the most adverse conditions. Depending on the year, it could be in the fall during turnover, or it could be brutal snow covered winters. It could be the amount of forage the BOW can produce (a food limitation). An increase in primary production provides not only food for carrying capacity but also additional DO as well, however, the nightly dips are more extreme and so there is a limit. Eventually an aquaculturist must aerate to keep DO at acceptable level as standing weights rise. Things can be going along well and then there are 4 cloudy days in a row in early October. You get the point here. It is that event that determines the carrying capacity. With aeration and feeding you have expanded the standing weight beyond what would be safe for a BOW without aeration.
In ponds with natural fertility and no feed input one can expect that the limitation is most often food, especially in in a yound BOW. I would estimate that your bow would support the maintenance of between 250 and 500 lbs per acre without feed inputs. I base that on averages that your State published in a pond guide that I once read and your location. As ponds age they collect nutrients and they progress toward greater carrying capacity. Carrying capacity depends in part on the type of fish you have. BH can attain higher standing weights than BG would in the same water. The mix of fish matters. The standing weight potential of only BG is greater than when BG are in combination with LMB. This is why BG might DO crash in a forage pond if you don't seine them out.
Standing weight ... its just what your fish weigh ... Hopefully enough description has been provided that it makes sense that a pond may have a standing weight greater than it can carry. These standing weights occur when conditions are favorable and the carrying capacity standing weights occur when conditions are less favorable and as part of the annual cycle of growth and consumption.
Thanks for the great explanations JPS! I have found the "Missouri Pond Handbook" that I believe you are referencing and added it to my initial post for safekeeping. For the record, it states...
"When the carrying capacity is reached, fish growth will slow down until some fish die or are removed. Ten-year-old ponds in Missouri average about 250 pounds of fish per acre of water. This usually includes about 190 pounds of bluegill, 35 pounds of largemouth bass, and the remainder will be catfish and other species. If you remove 25 pounds of fish, 25 pounds will grow back. This 25 pounds of fish may grow back as 100 4-ounce fish, or perhaps five fish of 5 pounds each, or any combination of sizes and numbers totaling 25 pounds."
...among other great information.
Thanks again! Time to get busy with population management.
Say listen, I've been lately giving some thought to building an excel spreadsheet for keeping harvest and catch data. It would involve one sheet for storing the data and another sheet with a pivot table and graphs made from the pivot table. In essence the additional sheet (or possibly sheets) would display the data organized by year, species, relative weights and so on. Given your enthusiasm, I have enough confidence in your interest to use it that I would like to design it around your existing protocol of measurement taking.
Just to give you an idea ... I am presented with differing options for determining weight. One is simply a length measurement that is converted to standard weight. This option may be favored by one who only takes length measurements. The other option would be weight measurement which is more accurate but maybe less convenient.
And so I would like you to give some thought about this and to some of the insights that you would like extract from your records and also whether you would be interested in using a spreadsheet like this. I would just post the excel file here in this thread and it would be available to all.
There are insights I would also like to extract from well kept records. One thing that greatly interests me are harvest numbers and how productive waters can be under differing management, species combination, and supplement fertility scenarios. In sharing something like this I would also hope that the information gathered might also be shared.
Your spreadsheet project sounds very cool. I think that most people who would be prone to using such a tool would be measuring AND weighing, but what little I know about spreadsheets tells me that it could be set up to to either. For example, most of the time I weigh and measure, but on occasion I just get a length. When both are entered, the spreadsheet calculates the pond's "standard weight" and can generate relative weight, but when only length is entered...it figures the standard weight from a table (I suppose) and goes from there. Given your mathematical abilities and all the pond calculation out there...the spreadsheet could get very involved.
I have not kept any fish for table fare, but I have culled medium sized HBG offspring. I will be culling larger HBG and a few HSB very soon (6 in the cage right now) and can see how such a spreadsheet could be used to estimate my two new favorite terms...Standing Weight and Carrying Capacity!
Keep me informed regarding your progress and I'll make stuff up as we go. I feel like I am talking to one of the controls engineers at work...I wave my hands and blabber a bunch of stuff on how easy it will be and how cool it will be and he walks away for a weeks worth of hair pulling.
Here is the first stab at it. Now I've locked all but the fields for data entry to prevent accidental deletion of formulas. This also helps with entering the data where a tab from the last column in a row takes you to the left most column in the next row. There are two tables to enter data ... one with catch data and another with trip data. I left the HBG Exponent and Multipliers unlocked so you could adapt them. I actually couldn't find a length weight chart for HBG so I averaged GSF and BG numbers to get the exponent and multiplier. Don't rely on it. If you have some data to work with I could solve the standard weight equation for your bow. If you already have ... please do share it with us. The last two tabs have pivot tables/charts displaying some fake data. Feel free to play and if you have any questions about how to manipulate the pivot tables/charts let me know. BTW I added the pivots before all the columns were complete and so some the table isn't presently accessible. You can however expand the data or create new tabs containing pivots with fields of all the secondarily computed data.
Here are the measurement methods supported.
1. Measured Length & Weight ... An RW is computed and one should enter only one fish in the # fish column. Actual weight will be in the Total Weight column.
2. Measured Length only ... No RW is computed and one should enter only one fish in the #Fish column. A standard weight will be used in the Total Weight column.
3. Measured Weight only ... No RW is computed. For this measurement one may used a combined weight of many fish. One should enter the number of fish in the combined weight in the #fish column. A standard length is computed. Actual weight is used in the Total Weight column. I thought this might be convenient for panfish harvests where one may not care about prey fish relative weights.
Since last week's testing, the aeration run time was only increased from 13 hours to 14 hours, but has been there all week. Whereas the week prior extended run times where at 5 hours to begin with and gradually moved to 13. Being at 13-14 hours all last week has shown some good improvement in DO, and clarity has improved by a few inches. I contribute the increase in DO to the longer air time and lower water temps, but feel the clarity improvement too insignificant to judge at this time (likely due to the lack of inflow).
Adding this last weekends readings...
Latest readings from Friday, Saturday, and Sunday (air from 8pm to 10am):
Friday evening's DO readings (6pm) -
8.2 ppm at the surface, 7.4 ppm 1 foot down, 6.3 ppm 2 foot down, 5.8 ppm 3 foot down.
Saturday's readings (Cloudy all day with periodic showers)-
Time - 8am in BOLD , 1pm in RED, 4:30 pm in GREEN
Ambient Temps - 73 F, 78 F, 82 F
Secchi Disk Reading - 25" all day long.
Water temps - Top to Bottom 73 F, Bottom 71 F - Top 76 F, Bottom 71 F - Top 78
DO - 6 ppm from surface down to 3', 7.2 ppm @ surface, 6.7 ppm - 12" down, 6.4 ppm - 24" down, 6.2 ppm - 3' down, 8.6 ppm @ surface, 6.7 ppm - 12" down. 6.6 ppm - 24" down, 6.3 ppm - 3' down
TDS - 50 ppm, Skipped, Skipped all taken at 12" deep.
Ammonia, Nitrates, & Phosphates - all zeros throughout the day.
Sunday's DO readings -
2" Rain over night and sunny this morning continuing throughout the day.
7:30am - 6 ppm from surface down to 3' (aeration now running 7:30 pm to 1:30pm)
6.2 ppm at the surface, 6.4 ppm 1 foot down, 6.3 ppm 2 foot down, 6.1 ppm 3 foot down.
At this point, I have to suggest that clearing the water from 12" to 24" (by removing some crawdads) and increasing air time from 5 hours to over 12 hour has improved the DO levels. Other possible factors are cooler air/water temps and the occasional showers and breezes keeping the water surface clear of pollen/dust-like floaties. I will consider increasing air time up to 24/7 operation for as long as fall temps permit, but have not committed to it just yet.
Fishing, or should I say catching, has increased significantly over the last few weeks. Anybody need any ~1/2 pound HBG for their pond?...I am collecting some in a cage to remove and aid in the DO levels, about 12 so far.