TyW � I spent several study sessions putting this together. I suggest you copy it as a reference. It should also be useful to others in the northern and north-central states who what to learn about and how to manage their pond with an emphasis on large bgill (Panfish Option; abundant bass & few greater than 15�). It discusses as much or more about the concepts of producing or managing for large, northern bgill than it does about my ideas about proper harvest.
�Managing for big bluegill is more difficult than say creating a trophy bass fishery � Pete Jacobson MN DNR� (InFisherman MayJun1994).
Not a lot of detailed information on the proper harvest of bluegills exists in the common �easy to get� literature. General guidelines for proper harvest are in several pond management booklets & books. Some of them recommend no harvest restrictions on bgill which is designed to keep panfish numbers in control (Kansas Ponds 1987, Missouri Ponds Handbook), and they conclude fishing emphasis should be on bgill harvest and not bass harvest. Some of the information on bgill harvest in these books assumes that the typical, relatively fertile pond contains a fishery of 250 to 400 total pounds of bgill per acre where water visibility would be 18�-24� for producing a productive fishery. These high standing crops of bgill will not occur in a pond that has clear water during most of the year i.e. where a white object can be seen 4ft to 12 ft deep.
For years biologists believed it was impossible to over-harvest bluegills or other panfish and the best bgill regulations of harvest were NO regulations. Newer information and research is emerging and has shown that angling can �fish down� bluegill and panfish populations. The length of 6� (152mm, �quality�) is considered the standard minimal size of a harvestable bgill for table use (Novinger & Legler 1978, Anderson&Neuman in Murphy&Willis 1996).
It has been found that anglers can definitely harm a bgill fishery by removing too many larger bgill. In the first month of a new bgill fishery in Maple Lk, MN, anglers removed 30% of the larger bgills. Anglers harvested 13% of the 6�+ bgill in the first three days at Mill Lake MI. At a new fishery in Third Sister Lake in MI, anglers removed 24% of the larger bgill in 3 weeks. In another example at Mid-Lake WI, anglers removed 35% of the bgill over 6� in the 1st month of fishing and after two years of angling total bgill mortality rate increased to 61%. Within 3 yrs most large bgill had been removed from Mid-Lake. Juvenile bgill often in northern states do not grow fast enough to rapidly replace lost adults and as a result bgill populations pressured by heavy harvest become composed of mostly fish less than 6� long. Sometimes when too many predators are removed, this can also result in overabundant, small panfish.
It can take 7 to 10 years to replace or regrow a large bgill on natural food sources in northern waters such as MI, WI or MN (also see below). Schneider 1999 and Patriarche 1968 reported bgill lived up to 11 - 14 yrs in four MI lakes. Removing larger numbers (over harvest) of bigger bgills contributes significantly to poor size structure of a bgill population (Coble1988).
Several books recommend bgill harvest in the range of 3 to 10 lbs of bgill for every pound of bass harvested. Illinois Pond Mgmt guide recommends the amount of bgill harvested should be based on the pond fertility and harvested amounts ranged from 20 to 160 pounds of bgill per acre (120-640 fish). Ohio Pond Mgmt Handbook recommends for a properly managed trophy bgill pond that 100-150 (6�-10�) bgill can be removed per acre per year. Michigan Pond Mgmt booklet recommends to �follow two harvest rules: 1. remove as many under 6� bgill as you can 2. greatly restrict harvest of over 6 inchers. This practice works against overcrowding and helps superior brood stock survive. Just as with bass, the biggest, fastest growing bgills bite most readily and tend to be caught first�. Cody thinks this is true up to a point. But after these caught and released fish get �hooked & jerked� several times, they tend to become hook shy and become cautious and more difficult to catch. However this behavioral trait may actually be beneficial especially in smaller ponds because it tends to protect these larger bgill from over harvest by you and poachers.
I definitely think that the number of bgill harvested per acre per year should be directly based on the pond�s fertility and the number of large bgill that are present. Schneider 1999 studied 11 of the better bgill lakes in MI. He noted that the �best� populations of larger bgill were predominately in lakes with low angler harvest of bgill.
Some fishery biologists are researching why and how some lakes consistently produce large bgills. Research is currently in the early stages but several features are emerging why some waters produce large bgills.
1. Presence of larger males tend to out compete smaller males who delay maturation and spawning while continuing to grow. Experiments (IL Natural Hist Survey) showed size and age of maturity is determined by how big the other males in the population are. When big males are removed, smaller males then become mature and establish a smaller maturation size group that is a smaller average individual size than before. Thus presence of big males inhibits young males from maturing while absence of big males encourages younger smaller males to mature. Cody thinks several forms of intraspecific competition probably contribute to this phenomenon.
2. High mortality of small bgill (less than age 1) caused by an abundance of smaller, average, sizes of predators. Smaller predators are forced to eat small forage items. Up to 48.3% of the diet of small bass in Blueberry Pond MI was very large numbers of bgill at 7 � 15 mm long (Schneider 1999). He concluded that the slow growth of one predator species (possibly crowding & stunting) tends to cause that predator group to prey primarily on small bgill, for example, crowded, small bass. . Also cannibalism of fry or larvae of or by large bgill can reduce intraspecific competition and allows faster growth of the remaining bgill YOY year class.
3. Presence of a �good� population of larger yellow perch in a pond with bgill also contributed a fair amount to age 1 mortality of bgill (Schneider 1999). He concluded however, that a high harvest of the y. perch can also lead to excessive bgill recruitment.
4. Low spawning activity or nesting success results in less need for predation and thinning of each year class thus improving growth rates. This justifies my comment about limiting the amount of spawning areas in the previous post. Schneider (1999) concluded it is unlikely that bgill spawn more than once a yr in MI. Peak spawn was May 25-31and at least some sporadic spawning occurred up to Aug 8.
5. Proper amount of macrophyte development provides refuge areas and production sites for abundant forage items for maintaing good growth rates of bgills. Overabundant macophytes can easily lead to over abundant panfish. In an exceptional fishery, Schneider (1999) reported that Michigan�s best large bgill fishery occurred in a unique, very weedy lake (83%coverage).
6. Diverse food web to accommodate the bgill�s generalist feeding tendencies which stimulates rapid growth of bgill. This includes an abundant food base of Daphnia (upto 2mm), Chaoborus, and midge larvae in the limnetic or pelagic zone and numerous types and an abundance of adult & larval insects and other miscellaneous invertebrates in the littoral & sublittoral zones (sediments and macrophytes).
7. Bgill were found to have diet shifts and feed primarily in the different zones at different life or size stages (Schneider 1999). Good growth requires ample food for each size class in each zone so bgill grow well during all developmental size classes.
Once a pond or lake produces large bgills it seems very important that these largest bgills should not be over harvested. The presence of larger bgills in a fishery helps maintain a quality fishery and it apparently has an impact of the future development of the overall bluegill population structure (Schneider 1999). .
The dilemma becomes for the pond manager is how many and what size of bgill to remove. A pond can withstand some type of annual harvest because a natural mortality will occur each year. I currently think the goal for a memorable or trophy bgill fishery should be to perform the larger part of the harvest from the midsize group (7.5�-8.9�) of bgill and occasionally harvest only a very few (0.5-1/ac/yr) of those in the largest (9.0 or 9.5�+) category each year. I recommend these fish should only consist primarily of bleeding deeply hooked fish. This will protect the largest bgill size classes and it will maintain a trophy fishery which is your stated goal. With this harvest technique or philosophy and ample food, you should be able to grow bgill to 9.5� or maybe 10+� if they live 11-13 yrs.
Some (primarily anglers) will strongly disagree with the above philosophy and argue that the largest and oldest bgill should be readily harvested and utilized before they die naturally of old age. This is a debate for another topic and I will not dwell on it here. I do agree with our mentor, Bob Lusk (and many on the In-Fisherman staff) who promote their conservation philosophy about trophy bass, and I think it also applies to large bgills: �these are trophies or rarities of nature and should be appreciated and held in reverence, and they deserve to be allowed to live out their entire life span in the pond not in the frying pan�. This philosophy is quite difficult to implement in public waters where �meat fishermen� prevail, however it can easily be used in private ponds. When a pond manager uses this harvest philosophy, then this is why anglers try their best and worst methods to get access and fish a pond that is full of memorable and trophy sized fish.
PBoss magazine discussed the basic concepts and philosophies of harvesting bgill, in the May-June2002 issue with an interesting cover story article (Selective Harvest, Pro Tips On Setting Effective Bag Limits),. It is recommended reading to provide good basic principles of fish harvest. In the article�s section on Bluegill Ponds, several authorities provided opinions regarding proper harvest, however few actual harvest numbers were reported which was probably due to the overall complexity of the topic.
Two of the best bgill lakes (large numbers of bgill greater than 8�-9�) in southern MI were studied for 6 yrs by Schneider 1999. Both lakes received low harvest of bgill and light overall fishing pressure. A few details of those fisheries follow:
Blueberry Pond, at 19.7ac, 22� deep, ave secchi 6.8ft, 83% macrophyte coverage w/ plant growth to 8ft, hard-water - alkalinity 105mg/L, BLUEGILL 8�-9� long (123-333 fish/ac) comprised 62% of the bgill stock greater than 6�. Stock greater than 6� ranged from 214 -506 bgill/ac.
Dead Lake, at 56ac, 30ft deep, ave secchi 14ft, 41% macrophyte coverage w/ plant growth to 13ft, hard-water �alkalinity 114mg/L, BLUEGILL 8�-9� (16-44 fish/ac) comprised 13% of the bgill stock greater than 6�which ranged from 208 - 237 bgill /ac.
The three next best bgill lakes in MI that contained populations of large bgill were:
Third Sister Lake � 8�+ bgill = 68/acre; fishing pressure low
Mill Lake 8�+ bgill = 22/ac; fishing pressure none
Jewett Lake 8�+ bgill = 4.6/ac; fishing pressure average (0.23), fish by permit, after 5 yrs of angling catch/hr steadily dropped from 1.42 to 0.42.
A wide range can occur in the numbers of large bgill that a pond or lake can naturally produce or sustain due to primarily the fertility of each water body. I think the key to proper harvest of bgill, and yet maintain a proper balance, is being able to estimate on a fairly regular basis the relative numbers of bgill present in each size class. Once these numbers are known then a harvest quota can be established. I always tend to error on the conservative side of the number harvested because I would rather be able to consistently catch larger fish, and harvest the medium sized individuals for the table compared to the opposite philosophy of eating the largest ones and in the future catch fewer large fish.
Another harvest philosophy involves keeping primarily the largest bgills because they will soon die of natural mortality.
Since bgill grow rather slowly in many of the northern states excessive harvest of the largest individuals can easily result in the population getting skewed toward the next smaller size class that may be growing slowly. This leads us to the benefits of pelleted feeding which: 1. promotes faster growth of intermediate sized fish to replace the larger harvested fish, 2. it helps maintain high condition factors of older fish and 3. it often helps in increasing the number of larger fish per acre. See caution items below.
Ohio�s DNR operates a public, premier, bass - bgill fishery in Lake La Su An - 82 acre lake - NW Ohio. It is composed of primarily bass and high numbers of large quality sized bgills (6�-10�); angling is by reservation only. ODNR fish surveys estimate that 30% to 40% of the bgill are 6�+. Compare this percentage to Blueberry Pond above that had 62% of all the bgills greater than 6� were 8�-9� long. At this point, I do not have any Lake LaSuAn fish survey data for the numbers of bgill that generally were in each incremental size group of fish greater than 6�. Daily and annual harvest at LaSuAn is strictly monitored at a park ranger check out station. When annual fish quotas are met the harvest of fish is strictly curtailed and fish harvest essentially stops for that year or season. Annual harvest of bgill in this productive, hardwater lake is set at around 100 bgill (6�+) per acre per yr (abt 50-60lbs/ac/yr). This figure is estimated to be about 30% of the adult population (6�+). The natural mortality of this lake in unfished years was estimated to be a 36% mortality rate (L.Goedde verbal).
After I have gone through all this information, I still have not given you an actual number of bgill that can be harvested from your new 12-15 acre gravel pit pond. I will assume your pond typical of many gravel pits that have fairly clear water and are lower in nutrients similar to Bluebery Pond and Dead Lake mentioned above. Harvest rates for these waters were: Blueberry =2.5 fish/ac (1%); Dead Lake = 5.5 fish /acre (3%). Other fish (bass, perch) were also harvested at low rates from these waters. The point to note here, is that exceptional quality fisheries in low productivity waters are at a very high quality status, probably partly due to low harvest rates, adequate growth rates and proper balance. I am not sure what the alkalinity of your pond will be, but I will assume it will be in the lower range of 30-60mg/L. The alkalinity of your new pond should be fairly similar to that of an existing, near-by water body with a similar �source� of water as your pond. As most here know that read to this point, alkalinity directly affects the phytoplankton productivity which ultimately affects the poundage of fish that a pond can grow without artificial feeding.
To be conservative and error on low side for your situation, I am assuming moderately low alkalinity and low natural productivity for your pond, which I am guessing will have a standing stock of around 75 to 100 lbs of total bgill per acre. Note, if you provide me with the alkalinity concentration of your pond, when it is full of water next year, I can adjust my calculations as needed. I am currently working on a simple formula to determine how many bgill should be harvested from ponds of varying fertilities.
Lets assume your bgill population / poundage is well managed with ample predation pressure on small individuals and the older year classes of bgill have a population skew of larger bgill of about 40% to be greater than 6�+ bgill. This assumes a lot of positives. With total standing crop of 100 lbs of bgill per acre, this results in abt 40 POUNDS of bgill/ac greater than 6�. I assumed the weight of bgill that are less than 2.5" - 3� to be in autumn or spring a fairly low poundage (abt 10lb/ac) due to predation and or manual thinning by you.
Your goal, as stated, was for harvesting is 8�+ bgill which will probably cause the harvest number to be somewhat low. This is due to in a normal population distribution, as the fish get larger, their numbers generally decrease, with the fewest individuals in the largest, oldest size class. For example in Blueberry Pond and Dead lake, as noted above, the numbers of bgill in the largest size class of 10+� there were two individuals in Blueberry an none were found in Dead Lake.
My estimated numbers of bgill 8�-9�long/ acre for your pond would be around 40
FISH/ac (20%) and for fish 9�+ long would be around 10 fish per acre (10%). Harvest about 30% to 40% of these numbers i.e. 15 to 20 fish per acre that are 8�+ /acre/yr. Keep good catch records and when the average size of fish you are catching gets smaller you need to look at making changes. Also note the condition factor or relative plumpness of the large bgill when you catch or clean them. Skinny or thin fish indicate over crowding (food shortages & or competition) and more numbers of one size group should probably be harvested to supply more food for the intended individuals. A fish feeder will probably increase fish condition factors and fish catchability (CPUE) in vicinity of each feeder. However, with out proper management this could still lead to overcrowding and possibly survival or life span problems.
CAUTIONS and TIPS; 1. It will take time to grow your first batch of fish to 8� and 9� which could possibly require 4 to 6 years in MN to see your first stocking (2�-3�) reach 8�. The fish growing season in MN is considered to be three months (Flickinger&Buglow in Kohler&Hubert 1993). However, in a new pond with a rich, abundant food web for bgill you could see 2�-3� stocked bgill grow to 8� in 3 full yrs which would be excellent growth in your location. You may want to initially stock 2 or 3 size classes to hasten the time it takes to produce 8� bgill. In WI slightly better than average growth of bgill is 1yr=2-2.5�, 2 yr= 4.8-5.7�, 3 yr=5.0-6.4�, 4yr= 6.6-7.2�, 5yr= 7.4-8.0�. Ave growth of bgill in IL was also similar to WI accelerated rates. Average MI growth rates are 1yr 3.1�, 2yr 4.3�, 3yr 5.4�, 4yr 6.6�, 5 yr 7.3�, 6yr 7.7�, 7yr 8.2�, 8yr 8.4�, 9yr 8.7�, 10yr 8.9�. Once a bgill, in MN growing season, reaches 7�-8�, I think its growth rate will be only �� to �� per yr. Overall bgill growth in your pond will very likely be at a somewhat slower rate AFTER the first several years in your new pond unless you supplement their diet with fish pellets. This is due to in the first few years of a new pond, the balanced numbers of stocked fish have the fastest growth rates compared to those when the pond fish populations stabilize (crowding) and a combination of numerous factors occur that can inhibit growth. Annually evaluating the forage food base and maintaining the proper fish density are impt tasks for properly growing your future year classes of fish. I think hand feeding or at least one artificial feeder is very important for growing large plump bgill at least in one localized section of the pond. Note that feeding the fish pellets is not just about growing more and bigger fish. Feeding should be combined with proper harvest or implementing population adjustments to improve the condition factors of the remaining fish yet maintain proper community balance. Many miss this important point.
2. Monitor or evaluate annually the small and intermediate sizes of bgill and adjust numbers if necessary. I spend much more time fishing for the small and intermediate sized fish than for the larger fish. Learn how to build and use fish traps.
3. Whenever fishing, continually monitor the relative plumpness of the bgill. When I clean fish, I always check for the amount of body fat. Thin fish are not getting enough to eat. Adjust densities as necessary.
4.. Spend a fair amount of time evaluating and tweaking the predator population so the majority of the predators are in the proper or targeted size groups to effectively crop bgill to meet your goals of producing big bgill.
The need to release large bgill depends on how many fish are harvested. Generally, releasing larger bgill can help sustain high catch rates of bigger bgill.
I wish you well with this new fishery. It will be a very good practical learning experience for you. Keep us advised on what you are learning and on the progress and growth of the fish in your new small lake. I also recommend that you keep good data or records and these bits of information will be very helpful in the future. Inquiring minds want to know.
