April 08, 2013
Spider rigging, or vertical trolling with multiple poles in a fanned out fashion, typically off the bow of the boat, has traditionally been a popular tactic to catch crappies in summer when they often inhabit open water, although its use has increased across the seasons. Creel surveys on Mississippi's popular crappie reservoirs suggest that spider-rigging has increased substantially in recent years. With an eye toward being proactive about possible increases in crappie harvest, researchers evaluated spider-rigging and single-pole fisheries—how catch rates differ between methods, whether catch rates of spider-riggers are related to the number of poles fished, and to what extent spider-rigging affects exploitation.*
The study was done on Sardis, Enid, and Grenada lakes, three Mississippi waters that are renowned for producing numbers of slab crappies. These reservoirs, in addition to Arkabutla, lie within a region dubbed the "Arc of Slabs" in In-Fisherman magazine. Over 2,200 crappie anglers making up over 1,218 crappie parties (628 pole fishing and 590 spider-rigging) were surveyed. Average trip lengths were 2.8 hours and 3.7 hours for pole anglers and spider-riggers, respectively. In spring, 90 percent of crappie anglers were polers; in summer 85 percent were spider-riggers.
Overall, spider-riggers had higher catch and harvest rates than polers, although patterns weren't consistent across the three test reservoirs. Spider-riggers caught just over 3 crappies per hour and harvested 1.72 per hour. Catch rate and harvest of polers was 1.18 and 0.86 fish per hour. For both groups, catch rates peaked in spring. Average weights of crappies caught also peaked in spring, with the smallest fish caught in summer and early fall. Weights didn't differ between groups at Grenada, while average weights were greater for polers than for spider-riggers at Sardis and Enid.
The effect of the number of poles used in spider-rigging on catch rates and harvest was studied at Sardis Lake. Catch rates by spider-riggers was related to the number of rods fished, although the relationship flattened as the number of rods increased. Catch rate and harvest were variable among spider-riggers, although in general the harvest rate by one spider-rigger fishing 3 poles was about the same as obtained by one poler (1.15 crappies per hour). When harvest was low, the number of poles didn't increase harvest rate.
The researchers conclude that crappie harvest should increase as the proportion of spider-riggers in a fishery increases, the number of poles used by spider-riggers increases, or both. Simulations predicted that in a fishery with a 50:50 mix of spider-riggers and polers, exploitation is about 1.3 times higher than in a single-pole-only fishery. If 100 percent of crappie anglers were spider-riggers, exploitation sees a 1.7-times increase.
Since 2007, the study reservoirs have been managed with a bag limit of 20 crappies and a 12-inch minimum length limit. Sardis and Enid lakes have a 5-pole-per-angler limit, while anglers are allowed only 3 poles at Grenada to sustain the trophy fishery. At a 50:50 ratio of spider-riggers to polers, harvest should remain sustainable. The researchers suggest, however, that as spider-rigging continues to increase in these waters, it can become a concern because crappie fisheries are mostly consumptive, which can lead to overexploitation.
Meals, K. O., Dunn, A. W., and L. E. Miranda. 2012. Trolling may intensify exploitation in crappie fisheries. N. Am. J. Fish. Mgmt. 32:325-332.