Anglers get excited about catching trophy fish. A few are obsessed with catching a record. Most are more casual, but catching the biggest of something still has an undeniable allure.
My surveys of more than 3,000 Mississippi anglers revealed that “knowing big fish are available to be caught” was very important in selecting a fishing site. This begs the question, are there any simple “rules” that an angler can use to judge the trophy potential of a water body?
Test The Waters
Nationwide reservoir assessments indicate surface area and growing season (number of frost-free days in a year) are good predictors of fish production. To test if these factors are also related to catches of trophy fish, Texas fisheries researchers analyzed rod-and-reel lake records for various warm-water species from reservoirs throughout Texas1.
They looked at lake records from small ponds to 185,000-acre Toledo Bend Reservoir. Growing season ranged from 186 frost-free days in the Panhandle to 341 along the coast. They found that growing season wasn’t important.
But record fish weight was positively related to surface area for 13 of 14 species. Bigger reservoirs produced bigger record fish, and the strongest relationships were for channel catfish, flathead catfish, largemouth bass and common carp.
But even the best fish-size-to-lake-size relationships accounted for less than 25 percent of the variation in fish size. In other words, other factors not measured in this study, such as habitat and harvest, had much more to do with record size than did surface area.
Big Fish Potential
The lack of a strong link between reservoir size and fish size probably doesn’t surprise you. Everybody knows of huge largemouth bass, giant ’gills and redears caught in small private ponds.
Growing big fish, regardless of the species, requires fast growth rates and high survival. Over the years, this column has explored effective strategies fisheries managers use to improve the abundance of large fish. Common to all are the basic tenets that good habitat and a good food supply produce fast growth; and appropriate harvest restrictions improve survival rates. These principles are little influenced by lake size or growing season.
But even under the best environmental conditions and low fishing mortality, truly trophy fish are a rarity. Even with catch and release, natural mortality plus the low mortality from hooking whittles away at the population, leaving few trophies after 10 or more years.
Given that the real giants of any species in a lake are rare, it has always struck me as odd that in the South, where lakes don’t freeze, winter is often touted as the best time to catch big bass, crappies and catfish. Strange that so many big fish are caught despite such low fishing effort. It seems that more lines in the water would improve the chances of giant fish being caught.
I’ve always wondered if high fishing pressure affects the behavior of big fish. A recent study offers an answer to that question, and we’ll cover it in the next Research Update.