Examining Black Bullhead Ameiurus melas Age and Growth in Shallow Minnesota Lakes

Authors

Michael S. Collins
Anna M. Medina

Document Type

Article

Abstract

Ageing methods, population age structures, and growth trajectories for Black Bullhead Ameiurus melas were evaluated for six populations from shallow lakes divided between two ecoregions in Minnesota, USA. A total of 693 fish were collected in July and August 2018 and measured for total lengths (TL) and weights (g). We collected ageing structures from 320 of these fish. Crosssections of lapillar otoliths (n=191) and pectoral spine structures (n=75) were used to estimate age by two readers in a blind reading procedure. Fish caught ranged in total lengths from ~40 to 350 mm and weighed between 8 and 380 g. Black Bullheads ranged in age from 0-6 years within both regions of Minnesota and exhibit relatively fast growth until age 3. After age 4, growth slowed down as they approach an asymptote of ~300 mm total length by age 6. Lapillar otolith age estimates had relatively high precision between readers (CV=11.02%), and a reader agreement of 83%. Pectoral spine age estimates had greater precision (CV=5.82%) with a reader agreement of 87%. Comparing the relationship between lapillar otolith and pectoral spine ageing methods yielded low precision and relatively high variability (CV=37.27%). Only 47% of age estimates between methods were in agreement. A linear regression model revealed variability in the relationship between spine lengths (mm) and estimated age (years) for both otolith and spine structures (R2=0.49, R2=0.39), respectively. Mean length-at-age shows variable growth patterns between each region of Minnesota.

Publication Date

2019

Comments

Note: Both authors should be considered first authors since they contributed equally to the project.

Faculty sponsors: Dr. Andrew Hafs, Department of Biology, Aquatic Biology Program; Brian R. Herwig; Dr. Danelle M. Larson.

Recommended Citation

Collins, Michael S. and Medina, Anna M., "Examining Black Bullhead Ameiurus melas Age and Growth in Shallow Minnesota Lakes" (2019). Journal of Earth and Life Science. 25.
https://pines.bemidjistate.edu/j-earth-life-sci/25