BIOL 316 Lecture 7 - Aquacultures + Lecture 8 Hatcheries & stocking

What is aquaculture?

Aquaculture = Domestication of wild stocks for human consumption.

Why is aquaculture important?

Aquaculture is seen as a solution to the global fisheries crisis due to overfishing and increasing world populations. It provides a source of fish for human consumption, especially as wild fish stocks decline.

What are the global trends in aquaculture?

• 60% of aquaculture occurs in freshwater, 35% in seawater, and 5% in brackish water.

• Canada is investing heavily in aquaculture, with a growing industry valued between 1 and 2 billion dollars.

• The Canadian industry grew rapidly from the 1980s, going from $7 million in 1984 to $256 million by 1991.

What economic impact does aquaculture have in Canada?

• $5.4 billion in economic activity

• $2.2 billion in GDP

• 25,000 full-time jobs

• $1.16 billion in labor income (2019)

What types of aquaculture are used in North America?

Most aquaculture in North America occurs in sea cages, but some operations use ponds or inland tank facilities.

What biological issues are associated with aquaculture?

• Source of feed: Many carnivores are fed fishmeal from wild species, putting pressure on wild stocks.

• Escapees: Farmed fish may escape, leading to genetic dilution and disease transmission.

• Habitat modification: Aquaculture operations may destroy valuable wetlands and nurseries for wild fish.

• Waste impacts: Uneaten food and feces can pollute local waters, especially in concentrated operations.

• Transgenic fish: The use of genetically modified fish raises concerns about environmental risks and public health.

What are the impacts of aquaculture waste?

Uneaten food and feces can lead to nutrient pollution, nitrogen waste, and altered water chemistry, particularly in small, concentrated areas like the Bay of Fundy.

How do aquaculture operations contribute to the spread of disease?

Proximity to wild fish migration routes increases the risk of transferring parasites and diseases from farmed fish to wild populations.

What are the potential solutions to aquaculture problems?

Move aquaculture inland to recirculation systems, possibly by 2025 in Canada.

Use polaculture systems (aquaponics) combining fish with plant crops to make systems more cost-effective.

Incorporate passive energy sources (solar, geothermal) into operations.

Develop greener, sustainable fish feeds that reduce reliance on wild fish.

What are the challenges of new aquaculture systems?

While recirculation and inland systems offer potential, the challenge is to make them cost-effective. The startup and operating costs for these new systems remain relatively high.

What are fish hatcheries?

Fish hatcheries are facilities that support the artificial fertilization of fish eggs and rearing of young fish for stocking into natural environments. They are used to support both recreational and commercial fisheries.

Why are fish hatcheries important?

Hatcheries help produce fish for stocking in natural water bodies, providing jobs, promoting awareness of fisheries resources, and educating the public about conservation and fisheries issues.

What types of hatcheries exist in Canada?

In Canada, hatcheries can be public (federal or provincial government-run), private (often run by fishing clubs), or a combination of both.

What historical role did hatcheries play in North America?

Hatcheries were first used in response to overfishing and habitat loss in the 1700-1800s. They became more common during the era of dam building in the 1900s, as a way to mitigate habitat loss caused by dams.

What major questions arose about hatcheries in the 1980s and 90s?

• How do hatcheries impact wild fish and ecosystems?

• Have hatcheries been successful in achieving their goals?

• Are hatcheries sustainable?

What are the behavioral impacts of hatchery rearing?

Hatchery fish raised at high densities with prepared food have different behaviors than wild fish. This includes:

• Reduced anti-predator behavior

• Increased vulnerability to predators

• Reduced reproductive success in the wild

What are the genetic impacts of hatchery fish?

Hatchery fish may undergo "domestication selection," where they adapt to hatchery conditions, leading to genetic differences from wild fish.

This can reduce genetic diversity in wild populations when hatchery fish interbreed with wild fish.

How do hatchery fish affect the genetic makeup of wild populations?

• Interbreeding between hatchery and wild fish can lead to inferior offspring, loss of local adaptation, and reduced genetic diversity.

• Indirect effects include removal of broodstock from wild populations and increased competition for breeding sites.

What were the debates around hatcheries and their effectiveness?

Although hatcheries were successful at producing large numbers of fish, the effectiveness of this approach was questioned due to the negative impacts on wild fish populations, such as habitat loss and overharvest.

Why did hatcheries persist despite their issues?

Hatcheries were seen as a quick fix, avoiding the more complex problems of overharvest and habitat loss. They became widespread because they provided an immediate solution without addressing the root causes of fish population decline.

What is the current consensus on hatcheries?

• Hatcheries should be used with caution.

• Hatchery programs must have clearly defined goals and be evaluated regularly.

• Hatcheries should be used in conjunction with habitat restoration and harvest limitations

What are the emerging roles for hatcheries today?

• Species restoration

• Gene banks for preserving genetic diversity

• "Put and take" fisheries to divert fishing pressure from wild populations

• Maintaining sport fisheries in permanently altered ecosystems, like the Great Lakes.

What are some criticisms of hatchery programs?

• Hatchery practices, especially in the past, have led to genetic and behavioral differences between hatchery and wild fish, affecting wild fish populations.

• In some regions, hatchery programs have been heavily scrutinized and reformed or eliminated.

Why is it important for future fisheries biologists to understand hatcheries?

Understanding the issues surrounding hatcheries is crucial for making informed decisions about fish conservation, management, and public education on the potential impacts of hatchery practices.