EFFECTS OF TEMPERATURE ON THE SURVIVAL AND GROWTH OF TWO CAMBARID JUVENILES

BY

YAVUZ MAZLUM1) Faculty of Fisheries, Mustafa Kemal University, TR-31040 Antakya-Hatay, Turkey

ABSTRACT Third instar eastern white river crayfish, acutus acutus (10 ± 0.04 mm TL), and red swamp crayfish, Procambarus clarkii (8 ± 0.02 mm TL) were stocked separately (intraspecific treatment) or in combination (interspecific treatment) at a density of 76 crayfish/m2 in 15-l aquaria. Survival and growth were assessed at 30-day intervals over a 90-day experimental period, ◦ ◦ ◦ which followed a fall (26-10 C), winter (10-10 C), and spring (10-26 C) temperature regime. A commercial crayfish feed (Zeigler 45-50% protein) was provided twice on five days a week. The survival of the two was similar through the fall and winter temperature courses; however, survival of P. a. acutus was significantly greater than that of P. clarkii under the spring temperature regime. The survival of each species was also better in the intraspecific than in the interspecific treatment during the spring period. No significant difference was detected in the growth of both species through the fall and winter temperature regimes. Over the spring temperature course, acutus grew faster than Procambarus clarkii in both treatments. In contrast to P. a. acutus, P. clarkii grew faster in the interspecific treatment than in the intraspecific one. The overall growth of P. a. acutus was 14 to 21% higher than that of P. clarkii for the fall, winter, and spring temperature regime over the total of 90 days.

RÉSUMÉ Des troisièmes stades d’écrevisses blanches de rivières de l’Est, Procambarus acutus acutus (10 ± 0,04 mm TL) et d’écrevisses rouges de Louisiane, Procambarus clarkii (8 ± 0,02 mm TL) ont été stockées séparément (traitement intraspécifique) ou en mélange (traitement interspécifique) à une densité de 76 écrevisses/m2 dans des aquariums de 15 l. La survie et la croissance ont été mesurées à des intervalles de 30 jours sur une période d’expérimentation de 90 jours, en suivant ◦ ◦ ◦ un régime de température d’automne (26-10 C), puis d’hiver (10-10 C) et de printemps (10-26 C). Une nourriture du commerce pour écrevisses (Zeigler 45-50% protéine) a été fournie deux fois sur cinq jours par semaine. La survie des deux espèces était similaire dans les conditions de température d’automne et d’hiver; cependant, la survie de P. a. acutus était significativement plus longue que celle de P. clarkii dans les conditions de température de printemps. La survie de chaque espèce était également meilleure dans le traitement intraspécifique que dans le traitement interspécifique

1) e-mail: [email protected] © Koninklijke Brill NV, Leiden, 2007 Crustaceana 80 (8): 947-954 Also available online: www.brill.nl/cr 948 YAVUZ MAZLUM en conditions de printemps. Aucune différence significative n’a été détectée dans la croissance des deux espèces en conditions de température de l’automne et de l’hiver. En conditions de printemps, Procambarus acutus acutus a grandi plus vite que Procambarus clarkii pour les deux traitements. Contrairement à P. a. acutus, P. clarkii a grandi plus vite en traitement interspécifique qu’en intraspécifique. L’augmentation totale de taille de P. a. acutus était 14 à 21% plus élevée que celle de P. clarkii en conditions de température d’automne, d’hiver et de printemps sur un total de 90 jours.

INTRODUCTION

Two species, the red swamp crayfish Procambarus clarkii (Girard, 1852) and the Gulf white river crayfish, (Hobbs & Hobbs, 1990) are the most important species cultured in North America. The other crayfish cultured in the United States, the eastern white river crayfish, is Procambarus acutus acutus (Girard, 1852). Crayfish culture is the only large scale commercial aquaculture industry in the U.S.A., and has an annual production of about 55 million kg with over 95% of the production coming from (Huner, 1995; Eversole & McClain, 2000). Huner & Barr (1991) reported that P. clarkii eventually dominated Louisiana culture ponds that were stocked with equal numbers of P. clarkii and P. zonangulus. In contrast, many of the ponds in South Carolina originally stocked with P. clarkii, were eventually dominated by P. a. acutus (cf. Pomeroy & Kahl, 1987; Mazlum & Eversole, 2000; Mazlum, 2003). It is assumed that the biological requirements are similar for P. clarkii and P. a. acutus (cf. Avault & Huner, 1985), but this may not be the case, judging from the emergence of a dominating species in the long term. Procambarid crayfish are cultured in extensive production systems in which unharvested adult crayfish (broodstock) produce small crayfish in burrows. Small crayfish emerge from the burrows when the ponds are reflooded and eventually recruit to the harvest population. Under these conditions, yield often varies among ponds and among production years. Reflooding has been shown to be important in determining the species composition of the harvest (Huner, 1995; Mazlum & Eversole, 2000) and to obtain larger-size populations of P. clarkii than of the later emerging P. a. acutus. The assumption is that earlier flooding may give a competitive advantage to P. clarkii juveniles. In contrast, when ponds are reflooded later in the season, the larger emerging P. a. acutus should have a competitive advantage over the smaller emerging P. clarkii (cf. Mazlum & Eversole, 2004). Competition occurs when P. clarkii and P. a. acutus occupy overlapping ecological niches (Wilson, 1975). Aggression and resource competition both are important components of crayfish interactions (Söderback, 1991). Butler & Stein (1985) indicated that sympatric crayfish species compete for limited resources such