Submitted to: Aquaculture
Publication Type: Peer reviewed journal
Publication Acceptance Date: 10/25/2006
Publication Date: 10/30/2006
Citation: Bosworth, B.G., Small, B.C., Gregory, D.J., Kim, J.M., Black, S., Jerrett, A.R. 2006. Effects of rested-harvest using the anesthetic aqui-s on channel catfish, ictalurus punctatus, physiology and fillet quality. Aquaculture 262:302-318. Interpretive Summary: Increased fish activity during harvest and transport prior to slaughter can have negative impacts on subsequent meat quality. Development of AQUI-S™ (active ingredient isoeugenol), an anesthetic approved for zero withholding time in fish in several countries, has led to use of rested-harvest (sedation during harvest) which leads to improved meat quality. AQUI-S™ is currently being reviewed for approval as a anesthetic with zero withholding time for fish in the U.S. Development of rested-harvest strategies could improve meat quality in U.S. farmed-raised catfish. A series of studies was conducted to determine appropriate levels of AQUI-S™ and effects of rested-harvest on catfish fillet quality. We found that 25-35 ppm AQUI-S™ were appropriate for rested-harvest of catfish. Compared to exercised fish or fish transported under simulated industry conditions, rested-harvest catfish showed reduced indices of anaerobic metabolism associated with degraded meat quality (muscle lactate, pH, ATP levels). Compared to controls, fillets from rested-harvest fish had better color and less drip-loss (water weight loss) but were not different for shelf-life. Rested-harvest with AQUI-S™ has potential to improve catfish fillet quality, but AQUI-S™ approval, development of rested-harvest strategies, and demonstration of economic benefits of rested-harvest will be required for adoption of rested-harvest by the catfish industry.
Technical Abstract: Trials were conducted to determine effects of AQUI-S™ sedation during harvest (rested-harvest) on physiological responses and fillet quality of channel catfish, Ictalurus punctatus. Doses of 25-35 ppm AQUI-S™ were effective for rested-harvest (RH) of catfish. Time to loss of equilibrium and time to recovery following sedation with AQUI-S™ increased as water temperature decreased from 30 °C to 10 °C. RH catfish had higher muscle and blood pH, lower blood and muscle lactate, and higher muscle ATP levels than catfish exposed to a 45 minute low-water stress or catfish collected at a commercial processing plant. Based on physiological response (higher muscle pH, lower blood lactate, delayed time to rigor), post-sedation euthanasia by CO2 was superior to post-sedation euthanasia by AQUI-S™ overdose (150 ppm), nitrogen gas, or electrical stunning. Compared to fillets from fish exposed to simulated industry transport conditions, fillets from RH/CO2 euthanised fish had higher pH 1 h post-slaughter, and less drip-loss and lower L* and a* color values during seven days of iced storage. RH/CO2 and control fillets were not different for shelf-life. RH with AQUI-S™ followed by CO2 euthanasia has potential to improve catfish fillet quality, but AQUI-S™ approval, development of rested-harvest strategies, and demonstration of economic benefits of rested-harvest will be required for adoption of rested-harvest to commercial catfish production.