A standard weight equation to assess the condition of North American lake herring (coregonus artedi)

Abstract

We developed a 75th-percentile standard weight (Ws) equation to aid in the analysis of lake herring (Coregonus artedi) body condition over temporal periods and across populations. Weight-length data were obtained for 23,115 lake herring from 61 North American populations. The proposed equation is log10 Ws = −5.517 + 3.224 log10 TL, where Ws is the standard weight in grams and TL is the maximum total length in millimeters. The equation is valid for lake herring ≥ 100 mm and allows calculation of the relative weight (Wr) index. Significantly lower (P<0.001) Wr values were present for Lake Superior lake herring populations than for the “inland” populations, suggesting that Lake Superior herring weigh less at a given length. Based on the world record lake herring length (55.9 cm), we propose minimum standardized length categories of 13,20,28,35, and 43 cm for stock, quality, preferred, memorable, and trophy lengths, respectively. The length categories facilitate analysis across length groups and the calculation of stock density indices. © 1998, Copyright Taylor & Francis Group, LLC.