Marine Debris in Humboldt County

Gyres in the ocean are created by the circulation of currents between continents. The North Pacific Gyre is comprised of four main currents that, when combined, encircle the Pacific Ocean north of the equator. The Kuroshio Current runs northward along the coast of Japan and the California Current runs southward along western Canada and the United States. The eastward North Pacific and westward North Equatorial Currents complete the circle in the north and south, respectively. Trash that enters the ocean from any source can accumulate within the gyre or wash up on any beach along the way. Currently, it is estimated that there are 30 tons of trash floating the in North Pacific Gyre 2. The "Pacific Garage Patch" or "Trash Island" has been heavily referenced in current global events and these terms refer to the debris accumulating in the North Pacific Gyre. In the map below it is labeled as "Convergence Zone".

North Pacific Gyre

Debris in the Marine Environment

Debris has the ability to travel through the world’s oceans via currents and can accumulate in the center of ocean gyres. Marine debris causes degradation of the ocean’s physical habitat, spreads chemical pollution, and threatens marine life. 1

Plastics are the most widely distributed and problematic type of debris, as they float along the top of the water column, and are not digestible once consumed by sea life 1. It is estimated that at least 86% of sea turtle species, 44% of all seabird species, and 43% of all marine mammal species worldwide are negatively impacted by plastic debris 3.

A recent study found that in the North Pacific Gyre the mass of plastic out-weighted the mass of plankton (small marine organisms) by six times, despite the fact that the number of individual organisms was five times higher than the number of plastic pieces 4. The same study found that 98% of plastics found were polypropylene/monofilament line (fishing lines), thin films and unidentified plastic fragments 4. Marine plastics have been found to have concentrations of pollutants, such as DDT (dichlorodiphenyltrichloroethane), PCBs (polychlorinated biphenyls) and PAHs (polycyclic aromatic hydrocarbons) that are an order of magnitude higher than that of the surrounding environment 1. This is problematic as the plastic fragments are serving as a transport mechanism to spread pollutants throughout the ocean. The amount of line floating in the ocean is also hazardous as it can result in entanglement of marine life. It is estimated that 135 species have been affected by entanglements which likely resulted in death or disfigurement 1.

Wildlife Found Entangled in Marine Debris

Debris can also alter marine habitats, as accumulations of debris can block sunlight, depriving marine plants of their needed light and decreasing visibility for other marine organisms. Debris can also accumulate along reef systems and physically destroy the habitat. As debris is washed into shallower water or sinks it can scrape against or break sensitive reef structures or smother habitat building organisms like corals 1.

Removing Debris from the Marine Environment

Removing debris from the marine environment as soon as possible is the best way to minimize the negative impacts of marine debris 1. Many types of debris, including glass and plastics, can stay in the marine environment for several hundred years. The figure below, released by NOAA, shows how long common items persist in the marine environment.

Cleanups along beaches and waterways are key to preventing debris from entering the oceans and impacting the marine life 1. Marine Debris from Land to Sea

More Information about debris in the marine environment can be found at:

NOAA Marine Debris Program

Marine Debris in the North Pacific - EPA Report


  1. Marine Debris in the North Pacific: A Summary of Existing Information and Identification of Data Gaps. U.S. Environmental Protection Agency , 2011.
  2. Hohn, D. (2008), Sea of trash, New York Times. [online] Available from: (Accessed 15 September 2012)
  3. Laist, D. W. (1997), Impacts of marine debris: entanglement of marine life in marine debris including a comprehensive list of species with entanglement and ingestion records, Springer Series on Environmental Management. [online] Available from: (Accessed 15 September 2012)
  4. Moore, C., S. Moore, M. Leecaster, and S. Weisberg (2001), A Comparison of Plastic and Plankton in the North Pacific Central Gyre, Marine Pollution Bulletin, 42(12), 1297–1300, doi:10.1016/S0025-326X(01)00114-X.

Figure References