Big Picture: Why Do We Care?
Some current seafood harvesting methods accidentally catch animals like sea turtles or damage habitats like coral reefs.
Current demand for seafood has caused fish to be harvested at a higher rate than the population's reproduction can keep up with. This has caused many fish populations to decrease over time.
Bottom line: we have to harvest seafood sustainably in order to have tasty seafood for generations to come.
Types of Seafood Harvesting
There are many types of fish in the sea, so there are many different methods to catch them! The list below includes some of the common harvesting methods, how they work, and the prominent sustainability issues related to it.
- A wall of netting which entangles fish when they swim into it
- Can catch marine mammals and other sensitive species
- A net wall where the bottom is pulled closed to catch fish as the net is lifted into the boat
- Often catches large amounts of unintended organisms
- While traps are normally considered fairly sustainable, one possible issue is lost traps. Traps that have been lost, often called ghost traps, create a positive feedback loop. The bait attracts animals which can't get out, when they die they attract more animals into the trap and the cycle continues.
- One long "main line" which has multiple fishing lines and hooks hanging from it
- Hooks can catch unintended animals
- A steel frame basket with a metal chain net that is towed behind a boat to rake up organisms under the sediment
- Used for animals like clams and other shellfish
- Disrupts sediment and damages habitat
- A large net that is dragged behind a boat that can be used in the middle of the water column or along the bottom of the ocean floor.
- Mid-water trawling can catch entire schools of fish at a time
- Bottom trawling can damage sensitive habitat
August 19, 2017 a fish farm near the San Juan islands had a large incident where Atlantic salmon escaped. Of the approximately 300,000 fish held in the net pen, it is estimated that 250,000 fish escaped. Since then, 57,000 of the 250,000 escaped Atlantic salmon have been recaptured. The introduction of these non-native salmon carries the risk of them outcompeting native salmon for food and introducing disease to our established populations.
One of the key concerns with farmed fish is the pollution. Net pens often contain densities of fish that are much higher than would occur naturally. Since they are in nets the fish require food inputs, and carnivorous fish like salmon require two pounds of wild fish as feed to grow one pound of salmon. Excess food, fish waste, as well as antibiotics and other chemicals being used flow through the cages into the surrounding ecosystem. This can cause algal blooms and other issues from the reduced water quality.
While farmed fishing may get a bad reputation for its ecological impact, farmed shellfish are a very different story. It has been estimated that 80% of the world’s wild oyster beds have been wiped out and now 95% of the world’s oyster consumption is being supplied by farmed oysters. Since the vast majority of oyster consumption is farmed, the sustainability of this industry is something worth thinking about.
One great thing about oysters is that they are filter-feeders. An oyster can filter up to 50 gallons of water per day, eating tiny particles, plankton, and organic matter found in the water column. Unlike fish which require food inputs and have the resulting waste which can pollute the environment, oysters can actually improve the water quality. This results in a sustainable food source, especially if you can buy locally to reduce your carbon footprint!
In recent years many human right issues have come to light from the seafood industry. While this is not included in most scientific determinations of sustainability, it is important to consider social justice issues when looking at the overall function of a fishery.
The Seafood Slavery Risk Tool produces a rating indicating the likelihood that human trafficking, forced labor and hazardous child labor are occurring on fishing boats in a specific fishery. The tool incorporates information from a variety of accurate, credible reports by authoritative institutions (U.S. government reports, EU and UN reports) and civil society organizations (universities, NGOs and media outlets) that are available in the public domain.