Caleb Schnitzler, Iowa Department of Natural Resources


Title of Presentation:

Age and growth of flathead catfish from Pools 12 and 13 of the Upper Mississippi River



Most research has shown that otoliths provide the most accurate age when compared to other structures: however fisheries managers often desire a non-lethal method for estimating age and growth.  We compared readability of otoliths and pectoral spines cut on the articulating process for estimating age and growth of flathead catfish from pools 11 and 12 of the Upper Mississippi River.  Structures were collected from commercially harvested flathead catfish, aged and compared.  Spine articulating processes otoliths both exhibited high variability in growth starting at age 1.  Readers could detect up to 17 annuli (mean TL=907mm) on spine articulating processes before loss of annuli occurred; whereas otoliths could be read to age 21 years (mean TL=968mm).  Annual and seasonal growth was calculated from flathead catfish that were captured from Pool 13 (Rkm 841.0 to 895.9), Upper Mississippi River, tagged with a visual implant tag and subsequently recaptured.  Actual growth over the summer was 0.009 inches/day and annual growth averaged 1.33 inches/year.