Effect of Various Electric Field Strengths and Current Durations on Stunning and Spinal Injuries of Atlantic Herring

Abstract

The aim of this study was to evaluate the effect of electric field strength and current duration on wild-caught Atlantic herring Clupea harengus stunned with sinusoidal 50-Hz AC in seawater. The fish were exposed to electric field strengths ranging from 16 to 142 V/m and current durations from 1 to 12 s. We recorded the elapsed times between the point at which each fish became unconscious and the points at which it resumed normal behavioral functions. We also investigated injuries such as broken spinal columns and hematomas after the fish were filleted. The threshold electric field strength required to stun all of the fish to unconsciousness was 33 V/m for 1 s. The duration of the unconscious condition increased as both electric field strength and current duration increased. Of a total of 260 Atlantic herring, 60% had broken spinal columns. The proportion of fish with fractured spines was independent of field strength and duration, but the number of fractures per fish increased with field strength. We conclude that electrical stunning would promote the welfare of Atlantic herring that are landed alive but negatively affect fillet quality owing to hematomas associated with the fractures.

<b>Impact of electrical stunning on fish behavior and meat quality of pacu (<i>Piaractus mesopotamicus</i>)

“…of recovery ( Table 1). The faster recovery of consciousness in pacus subjected to application of continuous current is consistent with the findings of Nordgreen et al (2008), who reported that the alternating current is more effective than the continuous current, with respect to the time that the electrically stunned fish become insensitive.…”

“…Fish can be subjected to both stages or directly to the second stage (Lines, Robb, Kestin, Crook, & Benson, 2003). Electric shock is one of stunning / slaughtering methods most studied in several fish species (Nordgreen, Slinde, Moller, & Roth, 2008). It consists in passing an electrical current in water or directly on fish until complete loss of consciousness .…”

“…It is considered humane because it is fast and apparently causes less suffering than other slaughtering techniques. However, several factors may influence the effectiveness of this technique, such as type of electrical current (alternating current -AC or direct current -DC) (Robb & Roth, 2003), voltage (Lines et al, 2003;Robb & Roth, 2003), frequency (Hertz) (Lines et al, 2003;Lines & Kestin, 2005), duration of electrical current (seconds) (Lines et al, 2003;Nordgreen et al, 2008), and water conductivity (Lines & Kestin, 2004). In sea bass (Dicentrarchus labrax) subjected to electrical stunning (40 to 120 V and 50 to 400 Hz) for 10 s, no recovery of consciousness was observed after 20 min.…”

Side-effects of electrotrawling: Exploring the safe operating space for Dover sole (Solea solea L.) and Atlantic cod (Gadus morhua L.)

“…The occurrence of electrically-induced epileptiform seizures depends on different parameters. It occurs more likely at higher field strengths, higher frequencies, longer pulse durations or longer exposure times (D'Agaro and Stravisi, 2009;Lothman and Williams, 1992;Nordgreen et al, 2008;Roth et al, 2003Roth et al, , 2004Sharber et al, 1994;Sharber and Black, 1999;Shigeto et al, 2013;Weiner, 1988). Frequency is reported to be the predominant factor in fish (D'Agaro and Stravisi, 2009;Roth et al, 2004;Sharber and Black, 1999;Weaver et al, 1974) as well as in other vertebrates (Lothman and Williamson, 1992;Shigeto et al, 2013).…”

Texture Measurements in Fish and Fish Products

“…Some attempts have been made to suggest that some mechanisms other than energy metabolism and rigor mortis are the source for accelerating the post-mortem tenderization. Nordgreen et al [14] and Roth et al [21] used electrical stimulation as a stunning method, on Atlantic salmon fillets, to reverse the stress response.…”