Thoughts On Harvesting Bluegill From Primarily Northern Ponds and Small Lakes.
Here is a pretty good summary about harvesting bluegill.http://www.pondboss.com/news/moderators-corner/bluegill-harvest-guidelines
Note to readers: The more detailed information below deals primarily with northern strain BG. Other strains of BG such as CNBG will likely have different features and results depending on conditions where they live. This essay is also available on the Website Bigbluegill.com.
The following discussion serves as more a detailed, background and review about harvest of bluegill (bgill, BG). Dr. Bruce Condello developed his above summary of BG harvest (above link) for producing trophy sized bgill using much of the following fishery research and his practical experience. I have experimented with and studied management for growing big bgill for numerous years.
”Managing for big bluegill is more difficult than for instance creating a trophy bass fishery – Pete Jacobson MN DNR” (In-Fisherman May-Jun 1994).
Not a lot of detailed information on the proper harvest of bluegills exists in the common “easy to get” literature. Generalized guidelines for the proper harvest of BG are in several pond management booklets & books. Some of them recommend no harvest restrictions on bgill which in theory is designed to keep panfish numbers in control (Kansas Ponds 1987, Missouri Ponds Handbook). Recommendations in these booklets conclude that 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 or develop from natural foods 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. Generally the clearer the water the lower the standing crop per acre will be.
For years biologists believed it was impossible to over-harvest bluegills or other panfish and the best bgill regulations of harvest were NO regulations. Harvest as many as you want. Now newer information and research is emerging, and it shows that angling can “fish down” bluegill and panfish populations, especially the larger individuals. For reference the total body 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 30 days of a new bgill fishery in Maple Lk, MN, anglers removed 30% of the larger bgills. At Mill Lake MI. anglers harvested 13% of the 6”+ bgill in the first three days And at a new fishery in Third Sister Lake in MI, anglers removed 24% of the larger bgill in just 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 the total bgill mortality rate increased to 61%. Within 3 yrs most of the large bgill had been removed from Mid-Lake. Juvenile bgill often in northern states do not grow fast enough to rapidly replace the removed adults and as a result bgill populations pressured by heavy harvest become composed of fish mostly less than 6” long. When too many predators are removed, this often results in overabundant, small panfish.
It can take up to 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 or 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 to reduce overcrowding and helps the larger superior brood stock survive. Just as with bass, the biggest, fastest growing bgills bite most readily and tend to be caught first”. I think 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 will often become cautious and more difficult to catch. However this behavioral trait of catch & release BG may actually be beneficial especially in smaller ponds because it tends to protect these larger hook smart BG 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 comprised of a smaller average sized individual 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. To learn how to recognize male and female BG see this link:http://forums.pondboss.com/ubbthreads.php?ubb=showflat&Number=286856&page=1
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 first year bass in Blueberry Pond MI was very large numbers of bgill at 7 – 15 mm long (0.25-0.6") (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 or another panfish 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 Michigan 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. I think the yellow perch often eat most of the small BG during the winter when perch are active and BG tend to be slow moving due to cold water.
4. Low spawning activity or nesting success results in less need for predation and thinning of each year class thus improving growth rates. This can be accomplished by limiting the amount of spawning areas. As Bruce has mentioned, removing more adult female bgill than males will also help reduce the number of eggs laid in nests. Schneider (1999) concluded it is unlikely that bgill spawn more than once a yr in MI. Peak spawn was May 25-31 and at least some sporadic spawning occurred up to Aug 8.
5. Proper amount of macrophyte development (underwater weeds) provides refuge areas and production sites for abundant forage items for maintaing good growth rates of bgills. Overabundant macrophytes 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 feeding every day which stimulates rapid growth of bgill. This includes an abundant food base of Daphnia (up to 2mm), Chaoborus, 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 (in sediments and among macrophytes). Rapid growing BG need to eat every day when water temperatures are above 50F and also feed regularly on cold water items mostly large zooplankton (cladocerans) during winter.
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 daily food items for each size class in each zone so bgill grow optimally each day during all developmental size classes from fry to old adults that will hopefully be trophy class fish. High protein fish food pellets provide this food requirement especially if the food web is lacking productivity.
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 normal pond can withstand some type of annual harvest because a natural mortality will occur each year. Bruce Condello, I, and other students of bgill, 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 (6”- 8”) of bgill and occasionally selectively harvest only a very few (0.5-3/ac/yr) of those in the largest (9.5" - 10”+) category each year. I recommend that 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 often the desired goal. With this harvest technique or philosophy and ample food, one should be able to grow bgill to 9.5” or maybe 10+” if they live 6 to 10 years. High protein pellet feeding can produce 9"-10" in 4-5 years.
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. This philosophy of preserving large fish is: “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 or water bodies with restricted access. When a pond manager uses this harvest philosophy, then this is why anglers will try their best and worst methods to illegally 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-June 2002 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 this complex topic that relates to water body size, productivity, and food web abundance & complexity.
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”. (Note: High density of leafy macrophytes have been shown to produce lots of invertebrate foods for panfish). Stock BG 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 of 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 = 68BG/acre; fishing pressure low
Mill Lake 8”+ bgill = 22 BG/ac; fishing pressure none
Jewett Lake 8”+ bgill = 4.6 BG/ac; fishing pressure average (0.23), fish by permit, after 5 yrs of angling catch/hr steadily dropped from 1.42 to 0.42.
From these data one can see the affects of fishing pressure which included bgill harvest.
From the info above, one can see 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 as a result 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 body condition factors of older fish (gravid females) and 3. it often helps in increasing the number of larger fish per acre. See CAUTIONS and TIPS below.
Ohio DNR’s High Quality Bgill Fishery
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 La Su An 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). I think if a stricter harvest quota was established as recommended by Dr. Condello and myself, this bgill fishery would go from very good to exceptional.
After I have gone through all this information, I still have not given you an actual number of bgill that can be harvested from a pond. I will assume a pond that has fairly clear water and is lower in nutrients similar to Bluebery Pond and Dead Lake mentioned above. Harvest rates for these low fertility clear 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. 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 the low side, I will assume moderately low alkalinity and low natural productivity for a pond, which I am guessing will have a standing stock of around 75 to 100 lbs of total bgill per acre.
Lets assume a 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 6” to be in autumn or spring a fairly low poundage (abt 10lb/ac) due to predation and or manual thinning by you. If the BG are regularly fed pellets then the standing crop could be near 200 –430 lbs per acre.
If a goal was for harvesting 8”+ bgill this will probably cause the harvest number to be somewhat low. This is due to in normal population distribution, as the fish get larger, their numbers generally decrease which results in 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 Lk and none were found in Dead Lake.
My estimated numbers of bgill 8”-9”long/ acre for our natural food item clear water 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 when you catch or clean them, note the condition factor or relative plumpness of the large bgill. Skinny or thin fish indicate over crowding (food shortages & or competition) and more numbers of one size group should probably be harvested to provide more food for the intended individuals. A fish pellet feeder will probably increase fish condition factors and fish catchability (CPUE - catch per unit effort) 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 depending on your location, food source or size of the stocker fish. The fish growing season in MN or MI 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 one could see 2”-3” stocked bgill grow to 8” in 3 full yrs which would be excellent growth in a northern or central US location. It should take fewer years in more southern states with a longer growing season. In WI and similar northern areas 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 the 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 reaches 8”, I think its growth rate will be only ¼” to ½” per yr depending on food supply and length of growing season. Expect overall bgill growth will very likely be at a somewhat slower rate AFTER the first several years in a 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 important 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 pond owners 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 or removing the small and intermediate sized fish than for the larger fish. I suggest you learn how to build and use fish traps or seines for evaluating your BG population.
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 and are growing slowly. Adjust densities as necessary to reduce competition and improve growth.
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 helps sustain high catch rates of bigger bgill.
When you understand and implement these above facts, ideas, and suggestions your BG population will respond by producing larger and higher quality bluegills.
Lakes and Reservoirs Program Manager
Nebraska Game & Parks Commission
RIGHT ON! I have seen far more panfish populations that suffer from over-harvest than I have seen largemouth bass or even walleye populations suffering from over-harvest. Now understand by "overharvest" I do not mean that those populations are in danger of going extinct, but that those populations are overharvested to the point where the fish are NOT able to reach their growth potential.
Bag limits are ineffective in reducing harvest unless bag limits are very low. In fact bag limits in public waters of only 5 panfish may be necessary to actually reduce harvest. In most cases bag limits that low are not acceptable to anglers. So, the best chance one has to produce some big bluegills while still allowing some harvest is to practice "selective harvest". Selectively choose the most abundant species and sizes of fish that can withstand the harvest. Panfish species like bluegills are prolific and can withstand some harvest, but even among panfish the big fish are rare
! Big bluegills are the best candidates for release! A self-imposed harvest slot limit like that already suggested is a great idea to take a few tasty bluegills home for a meal of fresh fish while maintaining those "pound-rounders" to be caught again and again!