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Animals 2018, 8(9), 158;

Physiological Changes as a Measure of Crustacean Welfare under Different Standardized Stunning Techniques: Cooling and Electroshock

Department of Biology, University of Kentucky, Lexington, KY 40506-0225, USA
Department of Medicine, Rostock University, 18055 Rostock, Germany
Division of Aquaculture, Kentucky State University, Land Grant Program, 103 Athletic Road, Frankfort, KY 40601, USA
Biomedical Sciences, Eastern Kentucky University, Richmond, KY 40475, USA
Biochemistry, Western Kentucky University, Bowling Green, KY 42101, USA
Sea Farms Limited, Redditch, Worcestershire B98 0RE, UK
These authors contributed equally to the experimentations.
These authors contributed equally to the manuscript editing and experimental design.
Author to whom correspondence should be addressed.
Received: 31 July 2018 / Revised: 5 September 2018 / Accepted: 10 September 2018 / Published: 18 September 2018
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Simple Summary

Physiological measures were examined during stunning of three commercially important crustacean species: crab, crayfish, and shrimp in an ice slurry or with electroshock. Neural circuits for sensory-central nervous system (CNS)-cardiac response and sensory-CNS-skeletal muscle were examined. Heart rate of shrimp was the most affected by both stunning methods, followed by crayfish, then crabs. Ice slurry and electroshocking may paralyze crabs, but neural circuits are still functional; however, in shrimp and crayfish the neural responses are absent utilizing the same protocols. The use of stunning methods should vary depending on species and slaughter method. Interpretation of behavioral signs should be supported by further research into related physiological processes to objectively validate its meaning.


Stunning of edible crustaceans to reduce sensory perception prior and during slaughter is an important topic in animal welfare. The purpose of this project was to determine how neural circuits were affected during stunning by examining the physiological function of neural circuits. The central nervous system circuit to a cardiac or skeletal muscle response was examined. Three commercially important crustacean species were utilized for stunning by immersion in an ice slurry below 4 °C and by electrocution; both practices are used in the seafood industry. The blue crab (Callinectes sapidus), the red swamp crayfish (Procambarus clarkii), and the whiteleg shrimp (Litopenaeus vannamei) responded differently to stunning by cold and electric shock. Immersion in ice slurry induced sedation within seconds in crayfish and shrimp but not crabs and cardiac function was reduced fastest in shrimp. However, crabs could retain a functional neural circuit over the same time when shrimp and crayfish were nonresponsive. An electroshock of 10 s paralyzed all three species and subsequently decreased heart rate within 1 min and then heart rate increased but resulted in irregularity over time. Further research is needed to study a state of responsiveness by these methods. View Full-Text
Keywords: blue crab; crayfish; electric stunning; euthanasia; icing; shrimp blue crab; crayfish; electric stunning; euthanasia; icing; shrimp

Figure 1

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Supplementary materials

  • Supplementary File 1:

    ZIP-Document (ZIP, 71721 KB)

  • Externally hosted supplementary file 1
    Description: S1. Whole shrimp in ice slurry. A live intact shrimp is placed in the ice slurry and within a second the animal starts to repetitively tail flip.
  • Externally hosted supplementary file 2
    Description: S2. Abdomen only in ice slurry. The head of the shrimp was cut off and the abdomen of the shrimp is rapidly removed from the body and placed in the ice slurry. The isolated abdomen starts to tail flip on its own as if attached to the intact animal. These rapid decapitated shrimp and removal of the abdomen experiments were performed at KSU.
  • Externally hosted supplementary file 3
    Description: S3. Abdomen with motor roots cut in ice slurry. The head of the shrimp was cut off and the abdomen of the shrimp is rapidly removed from the body. The motor nerve roots were rapidly cut along each side of the abdomen before placing the abdomen in the ice slurry. The isolated abdomen does not tail flip on its own when the nerve roots are cut. These experiments were performed at KSU.

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Weineck, K.; Ray, A.J.; Fleckenstein, L.J.; Medley, M.; Dzubuk, N.; Piana, E.; Cooper, R.L. Physiological Changes as a Measure of Crustacean Welfare under Different Standardized Stunning Techniques: Cooling and Electroshock. Animals 2018, 8, 158.

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