Marine Aquaculture and the Environment

In the United States, aquaculture is regulated under stringent federal and state laws and regulations that protect the environment. Through lessons learned over time and by engaging in aggressive research, aquaculture operators have developed commonly-accepted Best Management Practices to minimize any impacts. Operators know it’s in their best interest to maintain a healthy environment for the fish and shellfish they are growing.

In some cases, such as shellfish and seaweed farming, aquaculture actually contributes to environmental health by sequestering nutrients and cleaning up the water. In addition to adhering to strict environmental and food safety laws, aquaculture operators work with state and federal regulators to continually monitor potential impacts of their practices.

Aquaculture operators in the United States must abide by a comprehensive suite of environmental regulations, which differ depending on the type of operation. For operations in marine waters, federal regulations address environmental issues including diseases, discharge, structures, the protection of threatened and endangered species, seafood safety, use of medication, feed ingredients, marine mammal protection, habitat, and consistency with state regulations, among others. 

The key federal agencies currently involved in offshore marine aquaculture include: the Army Corps of Engineers, which issues permits for activities on or in navigable waters of the United States under Section 10 of the Rivers and Harbors Act of 1899; the Environmental Protection Agency, which issues permits for waste discharges into public waters under the Clean Water Act; the National Oceanic and Atmospheric Administration, which manages U.S. fishery resources in the EEZ. 

Disease is a fact of life in all animal populations and production systems on land and in water. When finfish aquaculture operations are in the marine environment, water moves freely between farms and the ocean. Risks include the amplification and transmission of disease between farmed and wild fish, and the introduction of nonnative pathogens and parasites when fish are transported.

Fish diseases occur naturally in the wild, but their effects often go unnoticed because dead fish quickly become prey. Disease events can occur in fish farms because 1) fish are reared at higher densities than nature, increasing contact between fish; 2) infected fish are not removed as promptly from the farm as they would be by natural predators; 3) farmed fish are more closely and easily observed than wild fish. Thus pathogens that normally exist in low numbers and do not cause disease in the wild may result in disease in farmed fish. Fish and shellfish farmers—as well as state and federal regulatory agencies—take many precautions to prevent infection and transmission of disease-causing pathogens and parasites. At commercial hatcheries, juveniles are reared under carefully controlled conditions to prevent the introduction of disease-causing agents from outside sources. Most states also have regulations requiring fish and shellfish to be screened before they are transferred to another site or released into the wild.

Many farmed fish are vaccinated against diseases that have caused problems in the past. Antibiotics are rarely used and, if required, their use is strictly regulated and always administered under the supervision of a veterinarian.

Nutrient discharge from fish farming operations is organic and comes from two sources – uneaten feed and fish waste. Both of these are biodegradable and readily used by most aquatic ecosystems. In the U.S., decades of experience have led to net-pen aquaculture in balance with the ecosystem. This comes from effective management plans, proper siting, and regulatory regimes that ensure minimum impacts to the environment. 

Antibiotic use in aquaculture has all but disappeared for species like salmon in most countries and is rare in others due to better husbandry and vaccines that have been developed for the major bacterial diseases. While good management practices and vaccines alone are usually enough to prevent or control disease, a farmer may, in consultation with a licensed veterinarian, use a limited number of aquatic animal drugs including antibiotics, in the case where they have been approved by the U.S. Food and Drug Administration (FDA) to treat specific conditions. 

Drug use in fish, as in land-based farm animals, is subject to strict application requirements. Before a drug is approved for use, FDA requires that it be demonstrated effective, safe for the environment, and safe for consumption.

When aquaculture is considered as an aggregate industry, the answer is no. Globally, aquaculture uses about half a metric ton of wild whole fish to produce one metric ton of farmed seafood, meaning that aquaculture is a net producer of protein.

However, concerns over the ecological impact of removing small pelagic fish and the rising cost of fishmeal and fish oil have driven innovations in sustainable aquaculture feeds. Today, partial or total replacement of fishmeal and fish oil in feeds has become the norm in commercial feeds. These alternative feeds seek to decrease the industry’s reliance on pelagic fish while maintaining fish and human health. Replacement options being developed include meals and oils from plants (the greatest source of protein and edible oil on earth), fish processing trimmings, yeast, bugs and other special meals, and even seaweed. Potential alternative ingredients already in use include soybeans, barley, rice, peas, canola, lupine, wheat gluten, and corn gluten.
 

Farmed fish enter the marine environment in one of two ways—intentionally or unintentionally.

Learn more about intentional releases of hatchery fish for enhancement and restoration

Advanced containment systems and improved management practices have dramatically reduced unintentional escapes. Advances in cage design and technology include stronger net material and improved mooring components. Best management practices include the use of underwater cameras to monitor and inspect cages, as well as the use of divers to perform hands-on inspections and maintenance. If fish do escape, impacts to the genetic diversity of wild fish are minimized by selecting founding hatchery broodstock from local wild fish so the genetic make-up is similar.

Typically, domesticated fish raised in captivity are poor performers in the wild and few of them are able to reproduce. However, researchers are now working on methods to make cultured fish sterile so, if they were to escape, they would not be able to breed with wild populations.

Federal and state permits require containment management systems at all marine sites, and these measures are enforced through regular inspections and audits. Equipment and husbandry will continue to evolve and improve as operators test new designs and materials.

Stock restoration or enhancement is a form of aquaculture in which hatchery fish, shellfish, and plants are released into the wild to rebuild wild populations or restore coastal habitats. Stock enhancement can be used as a management tool to help rebuild populations depleted due to overfishing, habitat loss, or other factors.

Learn more about abalone stock enhancement

Learn more about salmon stock enhancement