NZSM Online

Get TurboNote+ desktop sticky notes

Interclue makes your browsing smarter, faster, more informative

SciTech Daily Review

Webcentre Ltd: Web solutions, Smart software, Quality graphics


A Humane End for Lobsters

The most common method of killing lobsters is not necessarily the most humane way.

T. E. Lowe and N.G. Gregory

Animals that are killed for meat consumption must be killed humanely. This means that they must not be stressed when they are handled, that they should be held at the place where they are to be slaughtered for only a short period and under appropriate conditions, and that the killing method does not cause pain or distress. These aims apply to livestock killed in slaughterhouses, to animals killed on farms, and to animals killed in restaurants.

Seafood shops and restaurants are coming under increasing scrutiny about the methods they use for killing rock lobsters. Some of the methods have received nationwide attention in recent years, including a live demonstration of the "tailing" method on TVNZ's Holmes show. Organisations such as the RNZSPCA are concerned that tailing is inhumane, and they want to see some clear recommendations on how rock lobsters should be killed properly. If the overall procedure is to be humane, the lobsters must be unconscious before they are cut up for making a meal or seafood dish.

A recent study by MIRINZ Food Technology & Research found that no fewer than eight procedures are used when lobsters are killed in New Zealand's seafood restaurants. Usually two or more methods are combined together. The individual methods are:

  • chilling: animals are cooled in a cold room, fridge or ice slurry
  • drowning: animals are placed in tap water
  • head spiking: animals are spiked between the eyes
  • chest spiking: animals are spiked through the chest wall from the underside
  • splitting: the body is split along its length with a knife
  • tailing: the body is severed, between the fore-half (cephalothorax) and abdomen, with a knife
  • freezing: animals are frozen using a kitchen freezer
  • boiling: animals are dropped into boiling water

A Humane End for Lobsters Figure A (6KB)

Lobsters should be chilled before being killed. This is the simplest way of making them insensible without damaging the edible parts of the body. In cold-blooded creatures like rock lobsters, chilling helps to reduce nerve function and metabolic activity. Chilling can be done by placing the animal in a slurry of ice in salt water, or by placing it in a refrigerator set at 2 to 4oC. When the animal is fully chilled it stops moving, and it does not respond to being handled. When this occurs the animal is insensible. To be effective the chilling temperature must be cold. Chilling at temperatures above 4oC does not guarantee complete insensibility, but rock lobsters can be kept alive at this temperature for up to two days.

Rock lobsters are marine animals, so placing them in unsalted tap water causes severe osmotic stress leading to drowning. In unchilled lobsters this would be an unpleasant experience for the animals, and they struggle before they die. Drowning can also cause the meat to be too soft, because it takes up water as part of the osmotic effect. Overall, drowning in tap water is not an appropriate method for killing rock lobsters, regardless of the water temperature.

A rock lobster has two chains of nerve ganglia, with interconnecting nerves, which run along the length of its body inside its shell (carapace). Splitting the body along its length, with a knife, damages these ganglionic chains and prevents the animal feeling anything in its body. The splitting method requires skill to ensure a humane kill in an unchilled lobster, and so the animal should be chilled before-hand, to prevent it from moving and mistakes occurring. When head spiking is done properly, it should damage the main ganglia at the front of the animal. In order to ensure that head spiking is humane the animal should be well-chilled beforehand.

Cutting across the ganglionic chain (tailing) and chest spiking do not cause immediate unconsciousness in unchilled lobsters. These methods cause limited damage to the nervous centres in the fore-half, so they are not humane if used on an unchilled animal.

Not many rock lobsters are killed by freezing or boiling. This is because these methods
affect the quality of the meat. Boiling tends to make the meat chewy, and if the meat is frozen it loses its fresh appearance. Boiling also causes the lobster to shed its legs (autotomy), and if the fore-half has no legs, it is no longer suitable as a garnish for serving rock lobster meals in the restaurants.

The most appropriate method for killing rock lobsters is to chill the animals properly, before killing by splitting or spiking. Chefs in the restaurants that use this method can be sure that they are killing the lobsters humanely, whilst preparing good quality crayfish meat.