Shelter competition in juvenile red swamp crayfish (Procambarus clarkii): the influences of sex differences, relative size, and prior residence

Using a resident-intruder model, 24-h resident juvenile male and female red swamp crayfish, Procambarus clarkii, were intruded upon by same or opposit e sex juvenile conspecifics that were the same size or larger than the resi dents. Relative size was significantly related to contest outcomes. Residen ts that were the same size as the intruders won a significantly higher prop ortion of their encounters than residents that were smaller than the intrud ers. Overall, neither sex nor prior residence was significantly related to contest outcome. There was clear shelter-related territorial defense in bot h male and female juveniles, and is very similar to that shown in adult con specifics. The provision of shelter for juveniles in the aquaculture of P. clarkii is especially important because of the shelter competition advantag e of adults. This indirectly increases juvenile vulnerability to heterospec ific predation and cannibalism by conspecific adults and juveniles. (C) 199 9 Elsevier Science B.V. All rights reserved.