Length-Weight Relationships Associated with Gender and Sexual Stage in the Northern Clearwater Crayfish, Orconectes Propinquus Girard, 1852 (Decapoda, Cambaridae)

Abstract

The northern clearwater crayfish, Orconectes propinquus Girard 1852, is a species native to
eastern Canada and the northern United States. Growth patterns and relationships of body morphometrics
were evaluated to understand its basic niche requirements. Growth and size relationships for gender, sexual
phase for adults and juveniles, and chelae length and width relationships to interpret information on sexual
dimorphism were determined. The log transformed carapace length-weight relationship for male form I (y =
3.3201x - 4.0205, r² = 0.9645, F = 1302.9, p = <0.001), and juveniles (y = 3.2792x - 4.0171, r² = 0.8721,
F = 709.2, p = <0.001) showed positive allometric growth rates, whereas male form II (y = 2.8831x -
3.4474, r² = 0.8268, F = 248.2, p = <0.001) and female (y = 2.9184x - 3.5313, r² = 0.9395, F = 1879.3,
p = <0.001) showed negative allometric rates of change with increasing length. Relationships between log
transformed carapace length and carapace width (y = 1.0425x - 0.3841, r² = 0.8964, F = 1945.8,
p = <0.001), carapace depth (y = 0.9468x - 0.2816, r² = 0.9018, F = 2065.2, p = <0.001), abdomen width
(y = 1.0413x - 0.4443, r² = 0.864, F = 1429.2, p = <0.001), chelae width (y = 1.2927x - 0.9998, r² =
0.6255, F = 375.9, p = <0.001), and chelae length (y = 1.3083x - 0.6281, r² = 0.7439, F = 653.6,
p = <0.001) for the total collected adult population grew at a negative allometric rate. According to the
body condition index b, growth rates showed increasing weight with length but were within the expected
allometric growth.