Assessing Channel Catfish Stocking Rates with Simple Growth Increment Indices
Paul H. Michaletz, Eric L. Dennis, Matthew A. Engel, and Craig S. Gemming
Abstract.—Large fingerling (>175 mm total length) channel catfish Ictalurus punctatus are usually stocked to maintain put-grow-take channel catfish fisheries in small lakes and impoundments. Because these stockings are costly, stocking the appropriate number of fish is essential in minimizing costs and creating a desirable fishery. Appropriate stocking rates may vary among lakes due to differences in lake productivity, fishing and natural mortality of channel catfish, and other factors. Growth rate is responsive to the many processes that exist in lakes and is commonly density-dependent, making it a desirable parameter for assessing stocking rates. Two growth-increment indices were developed that compared size-specific growth increments within a population to statewide growth-increment percentiles for Missouri. These indices were used to determine responses in channel catfish growth rates in seven lakes where stocking rates had been either substantially reduced or increased. Sampling channel catfish populations after 3 years under the new stocking rate showed that growth increments and size structure did not substantially change. Both indices were correlated with growth increments and provided a way to assess growth relative to other populations. The lack of response of channel catfish populations to the new stocking rates suggests that these populations will not quickly respond to changes in stocking rate. The growth increment indices should assist managers in determining appropriate stocking rates and other management strategies.