Premium
Evaluation of Three Different Structures Used for Walleye Age Estimation with Emphasis on Removal and Processing Times
Author(s) -
Isermann Daniel A.,
Meerbeek Jonathan R.,
Scholten George D.,
Willis David W.
Publication year - 2003
Publication title -
north american journal of fisheries management
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.587
H-Index - 72
eISSN - 1548-8675
pISSN - 0275-5947
DOI - 10.1577/1548-8675(2003)023<0625:eotdsu>2.0.co;2
Subject(s) - emphasis (telecommunications) , estimation , fishery , computer science , environmental science , biology , engineering , telecommunications , systems engineering
We compared the removal and processing times required when scales, sagittal otoliths, and dorsal spines were used as age estimation structures for 160 walleyes Stizostedion vitreum collected from six water bodies in South Dakota. Removal and processing times were calculated by 10 fish groups. Dorsal spines required the least amount of time for removal, followed by scales and otoliths. Whole‐view otoliths required no further manipulation prior to estimating age, while the sectioning of dorsal spines and scale pressing required 12.5 and 16.6 min of additional processing time, respectively. Dorsal spines and scales also required significantly more time to read than otoliths. In terms of total processing time, whole‐view otoliths proved the most time‐efficient approach for estimating the age of walleyes. Scales were slightly more time‐efficient than dorsal‐spine sections, and sectioning otoliths would add additional processing time. Sectioning may not have been necessary in this evaluation because ages estimated by an experienced viewer from the sectioned otoliths agreed with ages estimated from whole‐view otoliths 98% of the time (although reader inexperience could result in lower rates of agreement). The relative precision between readers was approximately five times greater with whole‐view otoliths than with scales or spines. Reader agreement rates associated with whole‐view otoliths were also significantly higher than rates for scales or spines. Based on our findings, otoliths provide the most time‐efficient and precise approach for estimating the age of walleyes.