What you catch depends largely on where you fish
Mississippi lakes and reservoirs are home to black and white crappies, and there are a few naturally produced hybrids swimming in their midst. Hybrid crappie — the offspring of mating between black and white crappies — are being investigated as a potential fish for stocking in small impoundments. Here’s what is known about catchability of these fish.
Catchability is measured by dividing the angler catch by the number of fish in a population. Let’s say a lake has equal numbers of catchable-sized black and white crappies. If anglers catch twice as many white crappies as black crappies, white crappies would have higher catchability.
Weis Lake, Ala.
This 28,000-acre Coosa River impoundment has abundant populations of black, white and hybrid crappies managed with a 10-inch minimum length limit.
Hybrid crappies grow much faster than black or white crappies, and therefore, reach harvestable size sooner. If all three sub-species had equal catchability, harvest would tend to select hybrid crappies because they would enter the fishery at a younger age and possibly result in long-term changes in the composition of the crappie populations and angler catch.
To assess their catchability, researchers at Auburn University compared the relative abundance of the three in trap-net and electrofishing samples — assumed to be reliable indicators of the actual abundance of the crappies — with the relative abundance of the three caught by anglers. Relative abundance is the proportion of each type of crappie in the catch with fishery sampling gears and in the angler catch. Genetic analysis was performed to ensure correct identification of each fish.
The proportion of black crappies caught by anglers was greater than the proportion in fishery sampling, and the proportion of white crappies in the anglers’ catch was less than in fishery samples. The relative abundance of hybrid crappies in the angler catch was similar to the fishery samples. Thus, black crappies had higher catchability than white crappies, and hybrid crappies had intermediate catchability.
Despite the differences in catchability, the survival rates of each type did not differ, and the angler catch did not appear to be affecting the composition of the crappie assemblage. This was especially informative, because a much-higher proportion of the faster-growing hybrid crappies were large enough to be harvestable. The lack of an effect of angling on the composition of the crappie assemblage may be due to only a moderate amount of exploitation in this large reservoir.
Mississippi’s large reservoirs contain primarily white crappies, while Tunica Cutoff — a Mississippi River flood-plain lake with abundant flooded brush — contains mostly black crappies.
Or so say the fishery assessments.
But Keith Meals, the Mississippi Department of Wildlife, Fisheries and Parks’ crappie guru and flood-control reservoir biologist, shared that the fishery assessments may be biased. Black crappies orient more to brush and cover; white crappies tend to occupy open water. Trap-netting and electrofishing in flooded brush tends to catch more black crappies, but sampling in open water or where brush is scarce tends to catch white crappies. Thus, water level and where samples are collected can affect the catch rates of the two crappie species in the fisheries sampling, possibly providing an incorrect assessment of the relative abundance of black and white crappies.
The relative abundance of the two species in the angler catch also depends on how anglers are fishing, according to Meals.
“Any more, 80% of crappie anglers are trolling, which is biased for white crappies since they are more (open water) predators,” Meals said. “Black crappies are more likely to hold on sunken brush and timber. If we see someone anchored near a marker buoy fishing a brush top, they likely have black crappies in the box.”
As elsewhere, hybrid crappies have a faster growth rate than black or white crappies in Mississippi waters, but they are less than 1% of the crappie community.
Meals’ observations about crappie habitat use presents potential problems for obtaining unbiased estimates of catchability for the different species of crappies and their hybrids. The Weiss Lake study was conducted in 1992 and 1993 before trolling became popular; nevertheless, when, where and how you sample crappies with fishery or fishing gear can affect estimates of catchability.
Indeed, crappie species may differ in catchability, but their inherent habitat-preference differences and angling methods strongly affect which crappie an angler catches.
What most anglers call “crappie fishing” is really fishing for two different species that often occupy different habitats and are caught different ways. Knowing what species of crappie you are catching may up your chances of filling the box. This can be especially important if the two species have different relative abundance or different population size structures.
Which crappie is it:
- 5 or 6 spines in the spiny (front) part of the dorsal fin
- Lateral coloration (except for spawning males) dark vertical bars
- Prominent dark spot at top back edge of the operculum (gill cover)
- Head relatively long
- 7 or 8 spines in the spiny (front) part of the dorsal fin
- Lateral coloration (except for spawning males) scattered dark spots or spots in horizontal rows
- Black spot at the top back edge of the operculum (gill cover) faint or indistinct
- Head relatively short