Quantitative methods to reconstruct length and weight of Great Lakes prey fish using bony structures

Session: Exploring Predator-Prey Relationships and Feeding Ecology in the Great Lakes (4)

Matthew Anderson, Albion College, [email protected]
Benjamin Turschak, Michigan Department of Natural Resources, [email protected]
Sergiusz Czesny, University of Illinois, Illinois Natural History Survey, [email protected]
Jory Jonas, Michigan Department of Natural Resources, [email protected]

Abstract

When analyzing the stomach contents of fish, bony structures persist longer than soft tissue. Improvements in the evaluation of fish stomach contents and use of bony structures in reconstituting total fish length and weight can make timesaving decisions easier when establishing laboratory workup and statistical procedures. Length measures from bony structures were evaluated to determine effectiveness in reconstituting the length and weight of thirteen prey fish species from the Great Lakes. Full vertebral column length measures provided the most accurate estimates total length of fish. With a few exceptions for species whose cleithra were difficult to extract, cleithra provided the second most accurate and least variable estimates of total fish length. Partial vertebral measures provided reasonable estimates of total fish length which were more variable than those obtained from cleithra or full vertebral measures. When a greater proportion of the vertebral column was measured estimates were more accurate and less variable. We present models for estimating total length and weight which are readily repeatable among different laboratory facilities and represent the error associated with their application. Standardizing quantifiable relationships will encourage consistency in data collection methods and the comparability of data sets when performing analytics from observed stomach contents.