Population balance2026-10-03

Too many small bass, or bluegill that never grow? Which, and how many to remove

Plenty of thin bass between 10 and 14 inches, big fat bluegill, and almost no 3 to 5 inch bluegill in the seine means the pond is bass crowded, and the fix is to take bass out: about 10 pounds per acre per year in an unfertilized pond, 20 to 40 pounds in a fertilized one, until the bass fatten up. Few bass, all large and plump, with every bluegill at 3 to 5 inches means the pond is bluegill crowded, and the fix is to stop keeping bass, add 20 to 30 adult bass per acre and thin the small bluegill. Two numbers from a sample, proportional stock density and relative weight, tell you which one you have.

What the field signs look like

Mississippi State Extension's Managing Mississippi Farm Ponds and Small Lakes (Publication 1428) puts it in one line: "When fishing produces large numbers of small bass and large bream, an overpopulation of bass is probable. When only a few large bass and many small bream are caught, the pond is probably overpopulated with bream." Oklahoma's How to Fix a Stunted Bass Pond describes the fish: "most, if not all, bass between 7 and 12 inches in length. They also tend to have skinny or sunken bellies, and their heads appear larger than would be expected of a bass of that size." A seine shows the same thing from the small end: Alabama Extension (ANR-0577) reads "few intermediate bluegill; many recently hatched bluegill" as bass crowded and "many intermediate bluegill and few or no young-of-year bass" as bluegill crowded.

Catch signs, from the Mississippi P1428 and Virginia DWR balance tables
What you see	Bass crowded	Bluegill crowded
Bass on the line	Many, easy to catch, mostly 9 to 12 inches, thin, few over 2 pounds	Few, large and plump, averaging 2 pounds and up
Bluegill on the line	Few but large, 6 inches or longer	Mostly 3 to 5 inches, thin and slow growing

Two numbers that settle it

Proportional stock density (PSD) is one number for a pile of measured fish. Following Anderson and Neumann (1996), it is "the number of fish ≥ quality length/number of fish ≥ stock length × 100." In plain words, you count the fish at or above stock length, count how many of those are at or above quality length, and express the second as a percentage of the first. The cutoffs are Gabelhouse's (1984): largemouth bass stock, quality and preferred lengths of "200, 300, 380" millimetres (8, 12 and 15 inches), and bluegill 80, 150 and 200 millimetres (3, 6 and 8 inches). The balanced ranges from Willis et al. (1993), reproduced in the Washington report linked above, are a bass PSD of 40 to 70 and a bluegill PSD of 20 to 60; Virginia DWR uses 40 to 60 and 20 to 40. A bass crowded pond has a low bass PSD and a high bluegill PSD, and a bluegill crowded pond has the reverse. The PondTools stock-density calculator (also standalone) takes the species and the number of fish in each length bin and returns the PSD.

Relative weight (Wr) is a fish's weight as a share of what a healthy fish of that length should weigh. Alabama Extension's ANR-1193 says fish "less than 0.80 or 80 percent of the standard are considered severely thin," and that "In balanced ponds, the relative weights for most fish will be greater than 0.9." It gives the diagnosis directly: "In bass-crowded ponds, the bass will have low relative weights with bass between 10 and 14 inches typically being very thin," while "In ponds with too many bluegills (bluegill crowded), the bass will usually have high relative weight with bluegill in poor condition." Weigh and measure twenty or thirty of each species and run them through the PondTools fish-condition calculator (also standalone), which takes the species, the total length in inches, and the weight in pounds and ounces.

Gabelhouse (1984) length cutoffs and balanced PSD ranges
Species	Stock	Quality	Preferred	Balanced PSD
Largemouth bass	8 in (200 mm)	12 in (300 mm)	15 in (380 mm)	40 to 70 (Willis et al.); 40 to 60 (Virginia)
Bluegill	3 in (80 mm)	6 in (150 mm)	8 in (200 mm)	20 to 60 (Willis et al.); 20 to 40 (Virginia)

How many fish to take out

How much you harvest depends on how fertile the pond is. Virginia DWR says in unfertilized ponds "you should be able to harvest up to 40 pounds of adult bluegill (about 120 fish) and 10 pounds of adult bass (about 8 to 10 fish) per acre per year," and in fertilized ponds "160 pounds of bluegill (600 to 700 fish) and 35 to 40 pounds of bass (30 to 35 fish) per acre per year." Alabama's ANR-0577 table, below, runs lower on bass and adds the trophy variants. For a pond that is already bass crowded, Mississippi's correction is "Remove 10 to 40 pounds (depending upon productivity of the pond and location within the state) of bass per acre by fishing (one time only)," Alabama's is "Remove 50 to 75 (35 lb) bass per acre," and Oklahoma's is a yearly one: "10 to 15 pounds of bass per acre each year until the problem is resolved," with the warning that it "may take years before you see improvements."

Bluegill harvest is pegged to bass harvest, and the peg varies. Virginia's instruction is to "remove at least 4 to 5 pounds of bluegill for each pound of bass removed," and Mississippi's is "a minimum of 10 pounds of bream for every pound of bass." For a bluegill crowded pond the direction reverses, and Virginia says: "Allow no bass harvest; stock 20-30 adult bass (greater than 12 inches) per acre." Mississippi describes the trophy bream variant as deliberate bass crowding: "you must minimize the harvest of bass, to result in a bass-crowded condition." The PondTools harvest calculator (also standalone) takes the acres, how the pond is fertilized or fed, and the goal (balanced, trophy bass or trophy bluegill) and returns the yearly pounds of each species from these tables.

Published bass harvest, pounds per acre per year
Source	Unfertilized	Fertilized	Bluegill per pound of bass
Virginia DWR, balanced	10 lb (8 to 10 fish)	35 to 40 lb (30 to 35 fish)	at least 4 to 5 lb
Alabama ANR-0577, balanced	10 lb	20 to 25 lb	bream up to 100 lb unfertilized, 200 lb fertilized
Alabama ANR-0577, trophy bass	15 lb	30 lb	bream up to 100 lb unfertilized, 200 lb fertilized
Alabama ANR-0577, trophy bream	5 lb	"10 every 4 to 5 yr"	bream 25 lb unfertilized, 50 lb fertilized
Mississippi P1428, bass-crowded fix	10 to 40 lb, one time, by productivity		minimum 10 lb
Oklahoma DWC, stunted bass	10 to 15 lb each year until resolved		4 to 5 lb

What Pond Boss regulars do

The forum's moderators run heavier bass harvests than the extension sheets. ewest (Moderator, Hall of Fame 2014) wrote in 2023 that "In LMB crowded waters it is a common suggestion to remove 20 to 30 lbs of LMB per acre per year," and in 2009 that a balanced southern lake gives up 10 to 20 pounds per acre per year, or 30 if it is already crowded. esshup (Moderator, Ambassador Field Correspondent) in 2020 advised 30 pounds per surface acre the first year, then monitoring relative weights and taking another 30 or dropping to a maintenance 20. ewest hedged all of it in 2009: a very clear pond may support only 25 to 30 pounds of bass per acre while a fertile one could hold 125, so no clear-cut rule applies without data.

For diagnosis they lean on relative weight. esshup in 2014: "take out all the LMB that are under 90% relative weight, not all bass or just those under 10in." Bill Cody (Moderator, Ambassador Field Correspondent) reported in 2013 that removing bass and tracking catches by relative weight improved an older pond's bass fishery. ewest cautioned in 2008 that feeding or fertilizing a crowded pond before fixing the population usually just makes more small fish. The dissent is about degree: Dave Davidson1 (Moderator) disagreed in 2010 that a bass-crowded half-acre pond is fine.

Where the sources differ

The forum's 20 to 30 pounds per acre per year is double the extension figure for an unfertilized pond (10 pounds in Virginia and Alabama, 10 to 15 in Oklahoma) and sits at the top of the fertilized range. That figure matches Alabama's trophy bass number and Mississippi's one-time correction, both written for fertile, crowded ponds; on a clear, unfed pond it can strip the bass out, which is ewest's own hedge. The bluegill peg is a second gap: 4 to 5 pounds per pound of bass in Virginia and Oklahoma, 10 in Mississippi. The balanced PSD ranges disagree too. Oklahoma's assessment table calls a bass PSD of 20 to 60 with a bluegill PSD of 50 to 80 balanced, while Willis et al. give bass 40 to 70 and bluegill 20 to 60, so a bluegill PSD of 45 is fine on one sheet and "reaching over-crowded conditions" on the other. The forum's 90 percent relative weight cull line has no extension basis; Alabama's line for "severely thin" is 80 percent.

What to do

Sample first. Oklahoma's assessment guide says to "use a 20 X 4 foot minnow seine with one-quarter inch mesh" from June to September. Log every bass and bluegill by length, with weights for thirty or so of each.
Run the two numbers. A low bass PSD with thin 10 to 14 inch bass and fat bluegill means bass crowded, and the reverse means bluegill crowded.
If the pond is bass crowded, keep every bass under 12 inches you catch and release the rest. Set the yearly pounds with the harvest calculator and expect it to take more than one season.
If the pond is bluegill crowded, stop keeping bass, stock 20 to 30 adult bass per acre, and thin the intermediate bluegill by seine or with a fall shoreline treatment done with professional help.
Measure again next year. Relative weights should climb toward 100 before you ease off.
Do not fertilize or feed a crowded pond before fixing the numbers, and do not add crappie.