ECBC fact sheet - Adverse Effects of Sea Cage Fish Farming on Cetacean Populations

ECBC Fact Sheet

The Adverse Effects of Sea Cage Fish Farming on Cetacean Populations.

Sea cages are used in the “production” of carnivorous fish species such as salmon, trout, tuna and cod.

Mounting evidence suggests that sea cage fish farming adversely effects the marine environment and those species, which depend upon it.

The effect on cetacean populations has been largely ignored, even though sea cage fish farming poses a significant threat to porpoises, dolphins and whales.

The farming of carnivorous fish does NOT relieve the pressure on wild fish stocks and cetaceans populations. The pressure on wild fish stocks, and indeed cetacean populations is increased significantly, as each farmed fish needs to consume at least 3-5 times its own weight in fish meal and oil (species dependent).

In order to provide fish meal and oil for farmed fish, industrial fishing vessels catch millions of tons of wild fish, including pelagic species, upon which cetaceans feed. Consequently, an increasing number of cetacean species have been forced to alter their diet, thereby compromising their physiological well-being. In addition there has been a marked increase in the number of cetaceans dying as a result of starvation.

High levels of cetacean bycatch occur in these industrial fisheries. Due to economic considerations, if a cetacean is found entangled in the net, tail flukes and pectoral fins are often cut off, or the animals are decapitated in order to remove them. Their bodies are then punctured to make them sink in an attempt to hide the evidence. These barbaric practices are carried out regardless of whether the animal is alive or dead - post-mortem results have shown this to be the case.
ECBC has evidence that levels of cetacean bycatch resulting from EU fleets fishing in the waters off West Africa are even worse than in EU waters.

Cetaceans, seals and birds become entangled in anti-predator nets, which surround fish farms. The exact figures relating to cetacean entanglement are not available, but the information that is available suggests that a significant number of cetaceans are dying as a result of entanglement in anti-predator nets each year.

Seal scrammers are acoustic devices, which are used to deter seals from taking fish from the sea cages. The intensity of the sound emitted causes pain and suffering to the seals. They do, however, become habituated to the sound and therefore the deterrent effect of the scrammers is significantly reduced. The evidence suggests that these devices have adverse effects upon cetaceans. Research in a number of countries has shown that cetacean populations have left and not returned to areas where scrammers were used.

Significant numbers of seals are shot in order to prevent them taking fish from the sea cages. There is also evidence that cetaceans and birds are also shot. Many are not killed initially, but die after days or even weeks of horrendous suffering. There are no available figures for the numbers of cetaceans and birds shot each year. However, there are approximate figures for the number seals– 3,500 each year.

Evidence suggests that the pollution from sea cage fish farms is destroying the marine environment, and causing harm to cetacean populations. Research in a number of countries indicates that cetaceans, inhabiting areas in close proximity to sea cage fish farms, have higher incidences of skin disease, and higher levels of toxic burden. The research also suggests that the mortality rate of first – born calves is significantly higher.