Effects of three cold weather event simulations on early life stages of Southern Flounder (Paralichthys lethostigma)

ABSTRACT

To determine the minimum age/size at which Southern Flounder, Paralichthys lethostigma, can safely be moved to outdoor rearing facilities in Texas, we examined survival of simulated temperature drops in two distinct life stages: premetamorphic larvae and two size classes of postmetamorphic juveniles (small = 9.8 ± 0.3 mm in TL; large = 19.7 ± 0.6 mm). Temperature was lowered by −0.33°C/h to 4°C, 7°C, or 10°C, held for 48 h and then raised at +0.33°C/h back to normal rearing temperature. Fish were monitored daily for survival. Larger postmetamorphic flounder had high survival for all temperature treatments (89%–100% survival), whereas both premetamorphic larvae and smaller postmetamorphic juveniles had low survival (<30%) for all temperature treatments.

KEYWORDS:

• Survival
• premetamorphic
• postmetamorphic
• temperature tolerance

Acknowledgments

We thank M. Fisher for providing statistical consultation and a review. We are grateful to R. Gamez and S. Walker for providing Southern Flounder from the Marine Development Center in Flour Bluff, Texas, and D. Abrego and Sea Center Texas Hatchery for providing additional Southern Flounder. We also thank Z. Kirsch for assisting in monitoring the study.