Effects Of A 12-Inch Size Limit On Smallmouth Bass Populations And Fishing Pressure In The Shenandoah River, Virginia

In 1964, five sections of the Shenandoah River ranging from 9.0 miles to 15.3 miles in length (average 11.4 miles) were selected for an airplane census of fishermen. The census was conducted on a randomized schedule2 for both days of the week and time of day for the counts, with weekend days weighted because of heavier fishing pressure on those days. These data for 1964 through 1967 were used to compute the total fishing pressure in these sections. Creel clerks were employed on a part-time basis in each of the five sections to gather information on the number of smallmouth bass, both undersize and legal size, as well as the number and sizes of channel catfish, sunfish, and other species caught. The number of hours each fisherman fished were also recorded. In three of the sections, mail boxes with measuring boards at hand were supplied at boat landings, or other points of access, so that voluntary reports could also be supplied by anglers. In 1964, there was no size limit nor closed season on smallmouth bass. Fishermen kept bass as small as six inches in length. The result was a serious depletion of stocks of spawning size and many complaints by fishermen. In 1965, a 12-inch minimum length size was imposed on Shenandoah River bass with an almost immediate improvement in fishing. The number of 9, 10, and 11 inch bass increased substantially, and persons fishing for the sport of it with artificial lures have been very pleased with the results. One interesting feature of the study has been a gradual decline in the total fishing pressure in the five river sections totalling 56.8 miles in length. In 1964 the total fishing pressure was about 140,000; in 1965, 118,000; 100,000 in 1966; and 75,000 fishermen hours in 1967. The reason for this decline in fishing pressure is not fully understood, but it is probable that fishermen like to exhibit their success in the form of fish taken home. In 1935, the catch of legal smallmouth bass (under the lO-inch limit) ranged as high as 1.0 smallmouth bass per hour, whereas in 1965-67, it averaged about 0.06 smallmouth bass per hour. In other words, it required about 17 hours to catch a take-home bass. The current records show a decided increase in catches of smallmouth bass of all sizes, but only a moderate increase in number of legal fish caught. One possible conclusion is that some fishermen are taking out many of the edible-size fish before they reach 12 inches in length. Bass nest counts indicate a substantial increase in fish of spawning size.

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