Came across this super interesting write-up from MN DNR fisheries specialist Steve Kubeny that I thought others might like to see, too. First a little background from Steve:
> Fish grow at different rates depending on which part of the country and what type of lake they’re living in. In general, fish in the southern parts of the country grow much faster than fish living in the northern part of the country. The growing season or the length of time that water temperatures are ideal for fish growth are longer the farther south a fish lives. There is even a difference in growth rates between southern and northern MN fish.
> In Otter Tail County [MN], fish typically only grow during 3 months of the year, Jun, July and Aug. Once water temps begin to decline in Sep, fish growth stops and excess calories are preserved as fat for the long winter ahead instead of continued growth. In the spring, energy is spent on spawning instead of growth. With such a short window of opportunity for fish to grow, many anglers are surprised to find out how long it takes to produce a “keeper” sized fish.
> The type of lake a fish lives in also determines how fast it may grow. Shallow, fertile bodies of water tend to warm quicker in the spring and have more productive food chains. Growth rates tend to be faster in these types of lakes. Deep, less fertile lakes take longer to warm in the spring and have less productive food chains, which leads to slower growth rates.
Now, here’s Steve outlining the average growth rates for the more-popular species in MN’s Otter Tail County. Keep in mind that most gamefish species sexually mature at about the same age as anglers consider them keepers:
> Walleye: Typically about 6” in length after their first year of growth. On average, a 14-15” walleye (1 lb) is 4-5 yrs of age. A 20” walleye (3 lbs) is usually 7-8 yrs of age. Walleyes in excess of 20 yrs of age have been documented in Otter Tail County.
> Bluegills: In most lakes, bluegills don’t reach a “keeper” size of 7-8” until they’re 6-8 yrs of age.
> Black crappies: Most anglers consider a 10” crappie a “keeper” and on average, a fish that long would be 5-6 yrs of age.
> Bass: A 14-15” bass (2 lbs) is on average 5-6 yrs of age. A 20” bass (5 lbs) is approximately 10-12 yrs of age.
> Northern pike: Typically reach an average length of 25” (4 lbs) at 4-5 yrs of age. A 34” pike (10 lbs) is 8-10 yrs of age.
> Muskies: Can reach lengths of 50” or more, which typically takes 15-20 yrs.
> Lake sturgeon: Don’t sexually mature until they’re 20-25 yrs of age, and will have attained a length of 50-60” or greater at that point.
If this stuff interests you like it does me, here’s some more info on how DNR biologists age fish. Thanks Steve!