Sustainable Aquaculture Starts With Healthy Fish

The Path To Sustainability

Sustainability has become an integral part of the aquaculture industry. Consumers and retailers alike are critical about fish quality, fish welfare, and the potentially harmful impact aquaculture has on the environment. For the salmon farming industry, keeping fish healthy and disease-free represents a crucial step toward sustainable farming. Both research and anecdotal evidence point to stress as one of the likely causes of poor fish health in salmon farms.

Healthy fish grow faster, reproduce better, suffer from less disease, and taste better. In intensive aquaculture, farmed fish are exposed to ongoing predation stress from seals. Because nets don’t prevent predation stress, only by removing seals from the entire fishing area can the 'fight or flight' reaction to seals be prevented.

GenusWave helps farmers implement sustainable fishing practices by eliminating predation stress and decreasing the acute stress that fish experience every day.

Because stress consumes a portion of the animal’s energy, stress over time can lead to compromised immune systems. In one study, Atlantic salmon were documented to have a 50% lower growth rate in weight than the control after 30 days of acute stress. The loss in growth may also result from poor and inconsistent feeding due directly to stress or disease.

 

As expected, the more often a fish is exposed to stressors, the greater the negative impact. Conversely, the reduction of environmental stress has been shown to increase growth rates for farmed salmon.

High levels of stress hormones (cortisol) released over time can impair the animal’s immune system, predisposing fish to bacterial disease. Because stress reduces antibody production, the body’s response to injury or infection is slowed, thereby increasing susceptibility to pathogens. Some fish farms have also reported a 4% – 5% increase in disease related mortality resulting from prolonged acute stress.

 

Additionally, stress has been shown to make salmon more susceptible to sea lice infestations. While antibiotics may be effective at lowering disease rates, the greater dependence on antibiotics leads to a range of negative consequences on both fish health and the environment.

By lowering acute stressors on salmon, research shows that feed is consumed and utilized more efficiently by fish because it is eaten, rather than fallen to the seabed to waste. Farmers are projected to save between 10% – 12% in ongoing feed costs.

 

In one study, after just 17 days, food consumption based on dry weight was 5.4% per day in controls versus 2.1% per day in stressed fish – a 61% reduction in food intake by the stressed fish. After 37 days, food consumption was 6.2 and 4.6% per day in control and stressed fish, respectively, indicating a 37% reduction in food consumption.

 

Solving Sea Lice

A New Approach To
Counteracting Sea Lice

Salmon’s immune system can handle most challenges. But over time, predation stress can tax a salmon’s energy reserves and overwhelm its defenses. When that happens, poor health and disease results.

 

In one study, salmon stress was linked to “moribund fish,” whereby fish exhibited depression-like behavior and even anorexia. A second and equally problematic outcome of acute stress is an increased susceptibility to sea lice.

 

Unfortunately, current methodologies used to manage sea lice infestations may actually make the situation worse. The reason is that treatments to remove sea lice also remove the salmon’s mucus. By stripping away their mucus, these treatments make the salmon vulnerable to sea lice re-infection and incapable of fending off other infections and diseases. When a salmon is infected with sea lice, its immune system is already compromised. By decreasing mucus production, salmon are left vulnerable.

 

GenusWave’s offers a new approach. By removing predatory seals from the aquaculture environment, nearly all predation stress is prevented. Logically, fish can return to their normal levels of mucus production. Although predation is only one of several stressors on farmed fish, a predation stress-free environment is a big step in the right.