Pond Boss Forums INTRO Questions & Observations Bluegill

John - Simple questions - but complex answers. Nature and its ecosystems are rarely simple; this includes dynamic fish populations. Your questions could be answered in several different ways depending how one interprets the question. As Bruce mentions, harvest numbers will depend a lot on the long term GOALS for the pond's total fishery.
For example
1. What do you mean by safely? Safely in terms of what goal for the fishery? Most will assume you mean without upsetting the overall balance and keep the fishery with a "good" or "normal" number of all sizes of prey and predators. The type of predators, trash fish and mix of panfish (prey species) will also affect the number harvested. If perdators are not managed or harvested, then this will eventually affect the number of harvestable bgill at any given time.

As others eluded to, Fertility of the pond also affects how many fish it produces a year to replace mortality -natural and harvest.

2. Bgill growth per year is determined by fertility and density of fish. Too many fish result in too many "hogs" feeding at the trough and food supplies run short thus slowing fish growth. How much bgill "SHOULD" grow per year may not be truly what occurs due to NUMEROUS factors - to name a few: fertility, fish density, genetics, forage diveristy, zooplankton populations (food chain), water chemistry, trophic conditions, amount or percentage of bottom that is anoxic.

Factors for numbers 1 and 2 are closely interconnected.

3. The life span of bgill as in many fish is dependent on heat units per year and how dense the year classes are of each species. Normal (whatever ever that is) bgill life span in your pond should be very close to what Bruce suggested. But a lot of variables will affect the life span.

You are dealing with a living animal (bgill) that is succeptable and vulnerable to all the surrounding environmental influences of Mother Nature. It is very hard to give you definate or specific answers because it always depends on numerous things the fish are subjected to.

There will be conditions and exceptions in every answer someone gives you.

In general, numerous fishery studies have shown that 20% to 35% (upto45%) total mortality of the adult (5"+) bgill occurs each year in public waters. Fishery managers strive for a harvest of around this number (abt 30%). But to arrive at this number one has to have an estimate of the total bgill present that are 5"+.

As Bruce notes, harvest of the bgill can be done so it skews the sizes of the remaining bgills to result in an A. average bgill fishery (normal blend mixed sizes), B. a propensity of smaller sizes (few greater than 8") or C. a trophy fishery (lots of big ones above 8").

In gerneral, if you have a normal balance of bgill sizes, I think that the smaller bgill you will accept as keepers the more fish you will be able to "safely" harvest each year. The reverse is also true the larger the minimum keeper size, the fewer you will be able to "safely" harvest per year. This is due to the natural or normal size structure of fish populations: more of the smaller sizes, decreasing numbers of each larger size class up to fewest numbers of the oldest, largest fish.

Before I commit a guess or recommendation of a SAFE number to harvest per year I would like to know your average, minimum and maximum secchi disk readings for the pond. Secchi disk values will provide me a relative value of the pond's productivity