Study Notes on Food Production and Fishing Practices

Food Production: Fishing and Aquaculture

TOPIC 5.8: Impacts of Overfishing

Required Course Content

  • ENDURING UNDERSTANDING EIN-2: When humans use natural resources, they alter natural systems.

  • ENDURING UNDERSTANDING STB-1: Humans can mitigate their impact on land and water resources through sustainable use.

Learning Objectives

  • EIN-2.J: Describe causes of and problems related to overfishing.

    • Essential Knowledge EIN-2.J.1:

    • Overfishing has led to the extreme scarcity of some fish species. This scarcity can lessen biodiversity in aquatic systems and harm people who depend on fishing for food and commerce.

  • STB-1.F: Describe the benefits and drawbacks of aquaculture.

    • Essential Knowledge STB-1.F.1:

    • Aquaculture has expanded because it is highly efficient, requires only small areas of water, and requires little fuel.

    • Essential Knowledge STB-1.F.2:

    • Aquaculture activities can result in contamination of wastewater, and fish that escape aquaculture systems may compete or breed with wild fish. The high density of fish in aquaculture settings can lead to increased incidence of diseases, which can then be transmitted to wild fish populations.

Vocabulary

  • Fishing: The practice of catching, trapping, netting, or otherwise procuring both freshwater or marine fish, as well as other aquatic animals including mollusks and crustaceans.

  • Overfishing: The exhaustive harvesting of fish stocks beyond sustainable levels, leading to depletion.

  • Bycatch: Non-target marine species that are unintentionally caught in fishing gear, often resulting in mortality.

  • Aquaculture: The farming of aquatic organisms including fish, mollusks, and aquatic plants under controlled conditions.

  • Bottom Trawling: A fishing method where nets are dragged along the seabed to catch fish.

Fishing

  • Definition: The method of catching, trapping, netting, or procuring aquatic animals including freshwater and marine species. Includes a variety of techniques and scales of operations.

  • Historical Context:

    • Fish has been sustainably harvested by humans since the Paleolithic era, long before the advent of agricultural practices.

Overfishing

  • Historical Perspective:

    • Fishing practices became largely unsustainable in the Western world since at least the 1600s, with industrialization in the 19th and 20th centuries exacerbating the situation.

  • Statistics:

    • Estimates indicate that between one-third and two-thirds of the world’s fish stocks are currently overfished. Some reports suggest that all of the world’s fisheries are experiencing overfishing.

    • Reliable estimates indicate that 60% of fish stocks are fully fished, with another 30% currently overfished.

  • Effects of Overfishing:

    • Decline in global fish catch since 1996 due to reduced populations of wild fish.

    • Overfishing leads to:

    • Low population sizes of fish.

    • Harvesting of increasingly smaller species over time.

    • Shifting baselines syndrome.

    • Reduced biodiversity in marine ecosystems.

    • Trophic cascades, exemplified by the removal of keystone species (e.g., sharks) that leads to increased grazing pressure on coral, resulting in reef destruction.

    • Economic and food security challenges particularly affect communities reliant on fishing.

    • Source: NOAA

Shifting Baseline Syndrome and Fishing

  • Description: A phenomenon where the perception of what is normal for fish populations shifts over time due to the gradual decline of species sizes or abundances.

  • Examples: Optional reading references, such as the NPR article "Big Fish Stories Getting Littler," which highlights photographic documentation of decreasing sizes and species composition of fish off Key West, Florida from 1957 to 1958.

Methods to Mitigate Overfishing

Governmental Regulation

  • Challenges:

    • Difficulty in regulating due to the disproportionate number of vessels relative to regulators.

    • Continuing belief in freedom of international waters, leading to challenges in implementing regulations.

    • Resistance may arise from fishing communities affected by regulations.

  • Measures:

    • Imposition of fines and taxes on overfishing.

    • Removal of subsidies that incentivize overfishing.

    • Setting fish prices that reflect true costs including environmental externalities.

Techniques to Reduce Bycatch

  • Bycatch Definition: Non-target species caught in fishing gear that typically die, even when released.

  • Examples of Reducing Bycatch:

    • Utilization of acoustic devices to deter non-target species.

    • Implementation of glow ropes/netting.

    • Use of bird scaring devices, dyed bait, lights, and scent compounds.

    • Selective use of different types of nets and hooks to minimize non-target catches.

    • Excluder devices and weaker hooks/breakaway lines to allow non-target species to escape.

    • Reduction or complete elimination of bottom trawling and long-line fishing practices.

Establishing Marine Protected Areas (MPAs)

  • Definition: Designated regions in oceans where fishing is restricted or entirely prohibited to facilitate recovery of fish populations.

    • MPAs are crucial for preserving areas typically used for fish spawning and juvenile growth.

    • Statistically only 6.35% of the world’s oceans are covered by MPAs, with just 1.89% classified as no-take.

Overfishing by the Numbers

  • Concept: Overfishing occurs when fish are caught at a rate faster than their natural reproduction can replenish.

  • Future Projections: If current exploitation rates persist, total collapse of all edible fish stocks is possible within 40 years.

  • Consumer Statistics: The top consumers of seafood include Japan, China, and the United States.

  • Trends: Overall fish stocks have declined approximately 90% from 1950 to 2011.

  • Fishing Efforts: 77.9 billion tonnes of fish are caught annually—greater than the weight of every man, woman, and child in the United States.

  • Global Population: 50% of the world’s population resides within 50 miles of coastlines.

The State of Our Oceans

  • Exploitation Levels: Up to 80% of the world’s fisheries are reported as being fully exploited or over-exploited.

  • Condition of Predatory Fish Stocks: Only 7% are in a recovering state, highlighting severe declines in populations.

  • Impact of Overfishing on Iconic Species: Cod stocks in Canada provide a historical example of overfishing, leading to significant decreases in viable populations.

  • Current Percentages of Species in Decline: Statistics on fish species indicate approximately 24% of large predatory fish are severely depleted, with many other species also exhibiting concerning declines.

Aquaculture

  • Definition: Also referred to as aquafarming or fish-farming; it entails the intentional breeding and rearing of aquatic species in controlled environments, ranging from fish, mollusks, to aquatic plants.

Pros of Aquaculture

  • Efficiency and Food Security: Aquaculture presents a highly efficient way to boost food security levels globally.

  • Resource Utilization: Requires minimal fossil fuel due to reduced travel distances.

  • Bycatch Avoidance: No bycatch is associated with aquaculture practices, reducing unintentional catches.

  • Waste Reduction: Helps minimize litter generated by traditional fishing practices.

  • Space Efficiency: Depending on species, aquaculture can be conducted in smaller bodies of water.

  • Market Advantage: Ability to harvest fish at a specific market size, catering to demand.

  • Environmental Benefits: Certain species, like bivalves, can improve local water quality and other species provide habitat.

  • Economic Impacts: Helps elevate local economies by increasing available food sources beyond natural limits.

  • Relief on Fisheries: Aquaculture serves to alleviate the pressure on wild fisheries and habitats.

Cons of Aquaculture

  • Environmental Degradation: Potential habitat destruction from aquaculture developments, particularly in sensitive ecosystems like mangroves and reefs.

  • Pollution Risks: Effluent from fish farms can lead to water contamination due to high waste concentrations.

  • Feed Sourcing Issues: Requirement for food inputs can lead to overfishing of other species, especially for higher trophic-level fish feed.

  • Genetic Concerns: Escape of farmed fish may interbreed with wild populations, raising concerns especially with genetically modified organisms (GMOs).

  • Disease Issues: High densities can facilitate rapid disease spread, affecting both farmed and wild fish.

  • Chemical Use: Reliance on antibiotics, growth hormones, and pigments in aquaculture practices may pose additional risks.

Modern Sustainable Aquaculture Practices

  • Description: A sustainable aquaculture operation could encompass spread-out fish pens in the ocean to avoid coastal habitat disruption, managing fish densities to minimize disease spread, and utilizing innovative feed sources such as insect protein cultivated from food waste.

  • Integrated Multi-Trophic Aquaculture (IMTA):

    • Concept involving raising different species (seaweeds, shellfish, and deposit feeders) in proximity to fish cages to recycle waste and minimize nutrient load impacts.

    • Benefits include the recycling of nutrients, providing economic diversity, and improving the ecological balance around aquaculture sites.

Environmentally Responsible Aquaculture Practices

  • Operations should aim to:

    • Generate more fish than they consume by using alternative feed sources.

    • Utilize low stocking densities to enhance fish welfare and reduce waste.

    • Raise native fish species to avoid introducing GMOs.

    • Reserve chemical use for emergencies only and avoid using investigational drugs.

    • Implement cage technologies that prevent fish escapes and interactions with marine wildlife.

References for Further Study

  • Videos:

    • "Ending Overfishing"

    • "Ocean Alert: Overfishing"

    • David Attenborough's explanation of solutions to overfishing.

  • Documentary: "Seaspiracy" – a nuanced look at overfishing, coupled with a critical evaluation of its accuracy.