Cowspiracy makes a clear case for adverse environmental effects of human agriculture and aquaculture. Aquaculture is the controlled harvesting of fish and other marine lifeforms from all kinds of marine habitats. Hunting aquatic life and agriculture provide food, income and jobs to communities abroad. Ipso facto, farming and fisheries are invaluable practices necessary for supporting humanity’s growing populations. Can terrestrial and in aquatic environments absorb our growing needs? Cowspiracy primarily deals with the agriculture’s impact on terrestrial biomass, and leaves aquaculture’s costs to the subsequent film, Seaspiracy. However, Cowspiracy does briefly address the drawbacks of overfishing and ocean pollution.

fish near water surface
Fish near water surface

What Is Aquaculture?

The National Oceanic and Atmospheric Administration (NOAA) defines aquaculture as “the breeding, rearing, and harvesting of fish, shellfish, algae, and other organisms in all types of water environments”. The problem is that fish and other marine species are being pulled from watery ecosystems at unsustainable rates. Natural production (birth rates) of aquatic species wont be able to keep up with population declines, causing species after to species to depleted by fisheries. Once a single species can no longer be profitably hunted, fish hunters move on to a novel species. Serial depletion affects both biodiversity and species richness.

The Cowspiracy Facts page sites a Food and Agriculture Organization (FAO) document which states that in the year 2017, between 51 – 167 billion farmed fishes had been killed for food. That same year an estimated 250 – 600 billion crustaceans were also farmed and killed for food. Even animals that are not eaten by humans are caught and killed inadvertently because of drift netting or trawling. Susan Hartland of Conservation Society says that animal populations are being extracted from oceans more quickly than they can recover. Marine species are therefore collapsing under the immense pressures of modern hunting. The unintended catches, sharks, sea turtles and dolphins, are referred to as bykill.

Keystone Species and Trophic Cascades

Apex predators often act as keystone species, meaning that they have disproportionately large effects in their natural environments. This makes the removal of sharks particularly concerning. As top predators, many sharks species exert top down influence in their respective food webs. The removal of sharks, and other keystone species increases trophic cascade risks. Trophic cascades are the ecological chain of events triggered by the removal or addition of top predators.

Agriculture, Aquaculture and Ocean Deadzones

“Livestock operations on land have created more than 500 nitrogen flooded dead zones around the world in our oceans…” According to Dr. Richard Oppenlander, an environmental researcher featured in the Cowspiracy film. Water pollution comes in the form of pesticides, herbicides, heavy metals, plastics and other waste material. However, animal agriculture is the leading cause of ocean pollution – a fact which is stated explicitly in the film. Animal agriculture run-off upsets nutrient balances in aquatic ecosystems by introducing phosphorus, nitrogen, manure and potassium from chemical fertilizers. These excess nutrients can cause alae blooms, leading to uninhabitable zones for marine species.

Bottom trawling contributes to inhabitable zones similarly. Bottom trawling, also referred to as “dragging” involves casting a fishing net to the sea floor. Trawling disturbs sediments along the sea floor which causes carbon to be released. Once carbon dioxide is released from sediments, it is then absorbed by ocean seawater. Rising levels of sea carbon support cause water to retain more heat and makes contributions more suitable for algae and plant overgrowth. Blooms of algae drain sunlight and deplete oxygen levels – making the environment unsuitable for most other lifeforms in the ecosystem.

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