The Effect of Rearing Density on Growth and Survival of Cobia

in a Closed Recirculating Aquaculture System

• Glenn M. Hitzfelder ^{a a} Maritech, Research and Development, 805 46th Place, Vero Beach, Florida 32963 USA
• G. Joan Holt ^{b,1 b} University of Texas at Austin Marine Science Institute, Fisheries and Mariculture Laboratory, 750 Channel View Drive, Port Aransas, Texas 78373 USA ¹ Corresponding author.
• Joe M. Fox ^{c c} College of Science and Technology, Texas A&M University – Corpus Christi, Corpus Christi, Texas 78412 USA and
• David A. McKee ^{c c} College of Science and Technology, Texas A&M University – Corpus Christi, Corpus Christi, Texas 78412 USA

• ^a Maritech, Research and Development, 805 46th Place, Vero Beach, Florida 32963 USA
  ^b University of Texas at Austin Marine Science Institute, Fisheries and Mariculture Laboratory, 750 Channel View Drive, Port Aransas, Texas 78373 USA
  ^c College of Science and Technology, Texas A&M University – Corpus Christi, Corpus Christi, Texas 78412 USA

¹ Corresponding author.

Cobia, Rachycentron canadum, is a highly prized game fish as well as an important commercial fish in many parts of the world. This species is found worldwide in tropical, subtropical, and warm temperate seas, except for the eastern Pacific. Cobia is thought to be highly migratory in the Gulf of Mexico where it is absent from commercial and recreational catches during the late fall and winter (Ditty and Shaw 1992). Cobia migrate from the Florida Keys north and west along the Gulf coast during early spring and reappear in the northern Gulf of Mexico in late spring and summer.

Cobia is an excellent candidate for aquaculture because of its fast growth rate, reaching 6–10 kg in 12–14 mo (Liao et al. 2004), as well as excellent flesh quality (Chen 2001). However, intensive culture of cobia is relatively new to aquaculture. Techniques for the natural spawning of cobia broodstock in recirculating aquaculture systems (RAS) have only recently been developed in the United States (Arnold et al. 2002). Although larval rearing techniques have been under investigation for the past few years (Faulk and Holt 2003, 2005), little information is currently available regarding optimal rearing densities for cobia in RAS. The availability of large numbers of larvae and/or juveniles is necessary for successful grow-out operations, so high-density larva culture is favored.

Stocking density has been shown to influence growth rate (Pickering and Stewart 1984), feeding behavior (Kentouri et al. 1994), disease resistance (Mazur and Iwama 1993), and survival (Sodeberg and Meade 1987) in finfish. Density effects on cultured fish may result in behavioral interactions among siblings including competition for food and space that often result in cannibalism. Reduced water quality in high-density rearing systems can also affect growth and survival. If water quality can be controlled and sufficient food provided, high rearing densities may still affect growth and survival through responses related to crowding. Reduced appetite is one of the effects associated with reduced growth of juveniles under crowded conditions (Wendelaar Bonga 1997). The effect that crowding has on larvae is not well understood, but it often results in reduced growth and survival (Houde 1975; Alvarez-Gonzalez et al. 2001). This study was conducted to evaluate the effects of different rearing densities on the growth and survival of cobia larvae in an RAS.

Blackwell Synergy - J World Aquaculture Soc, Volume 37 Issue 2 Page 204-209, June 2006 (Full Text)