Use of reflex indicators for measuring vitality and mortality of the snow crab (Chionoecetes opilio ) in captivity

Abstract

The snow crab (Chionoecetes opilio) is one of the most important commercial crabs in the world; it is heavily exploited in Atlantic Canada, Alaska, the Sea of Japan and the Barents Sea. Catches in the Barents Sea north of Norway have increased dramatically in the last decade. Most of the world's catch is processed, frozen and exported overseas. However, recently there has been considerable interest in exporting live snow crab, particularly in Norway. The stress of capture and live transport can result in significant mortalities. In order to establish a live export industry for snow crab, the welfare of the animal must be monitored throughout all the steps of the live transport process. In this study the reactions of snow crabs exposed to increasing periods of air exposure were measured in terms of reflex indicators, incidence of mortality, blood lactate levels and blood protein and haemocyanin. Although this is not a specific live holding or live transport process the aim was to test the suitability of reflex indicators to reflect vitality (stress) and not just to predict mortality. This would be compared with traditional blood biochemistry techniques for measuring crustacean stress. The study demonstrated that the reflex index score (RIS) is suitable to assess the vitality of snow crab. Longer air exposure periods render higher mortality rates and less vital individuals. The authors believe using vitality reflex indicators would be a suitable way of measuring crab welfare during the live holding and transport process.

Effect of different diets on growth performance, physiological response and behavior of spiny lobster Panulirus homarus (Linnaeus, 1758)

“…In general, it can be concluded that the best seed vitality performance was obtained in treatment I followed by treatment K, and lastly, treatment U. Reflex impairment scores significantly correlated with fry vitality Reflex and behavioral measures are valuable indicators of vitality and mortality in the commercial trade in crustacean species (James et al (2019);Stoner. (2012); Turnbull et al (2021)).…”

“…In addition, metabolic products such as hemolyzed glucose can be used to determine stress levels in crustaceans due to treatment in rearing, pollutants, handling, environmental changes, and post-transportation (Lorenzon et al, 2007;Gulec and Aksu 2012;Bislimi et al, 2013;Arifin et al, 2014). Other parameters that can be used as a reference in determining the vitality and health level of lobsters are reflex or behavioral responses to indicators of vitality which are quick and easy to measure and have been shown to reliably correspond with prolonged whole body performance (James et al, 2019;Stoner, 2012;Turnbull et al, 2021). Reflex actions are consistent, involuntary and nearly instantaneous, and are independent of size, strength, motivation and gender (Turnbull et al, 2021).…”

Lobster Supply Chains Are Not at Risk from Paralytic Shellfish Toxin Accumulation during Wet Storage

“…Reflex actions are consistent, involuntary, nearly instantaneous responses to stimuli which can reliably indicate crustacean whole-body health status independently of animal size, strength, motivation and gender [12]. Crustacean reflex scores have been previously used to provide an accurate indicator of crustacean performance in supply chain studies [12,[17][18][19][20]. Other commonly used methods to assess lobster gross or whole-body performance include survival and nutritional condition [16,19,21,22] Physiological indicators for the assessment of the health and vitality of crustaceans commonly include immune responses (raised bacteraemia levels and changes in haemocyte counts [21,[23][24][25][26]; and haemolymph concentration of ions (e.g., potassium, sodium, magnesium, calcium, bicarbonate, pH), metabolites (e.g., ammonia, urea, glucose, lactate) and hormones (e.g., crustacean hyperglycaemic hormone) [21,25,27,28].…”

“…Reflex actions are consistent, involuntary, nearly instantaneous responses to stimuli which can reliably indicate crustacean whole-body health status independently of animal size, strength, motivation and gender [ 12 ]. Crustacean reflex scores have been previously used to provide an accurate indicator of crustacean performance in supply chain studies [ 12 , 17 , 18 , 19 , 20 ]. Other commonly used methods to assess lobster gross or whole-body performance include survival and nutritional condition [ 16 , 19 , 21 , 22 ]…”