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Effect of deepwater oil spills on marine fishes

Contributing AuthorsContributing Authors
Effect of deepwater oil spills on marine fishes

Oil spills occur when people are careless and cause an oil tanker to leak oil into the ocean. There are some other ways for causing an oil spill like equipment breaking down may also cause an oil spill. If the equipment breaks down, the tanker may get stuck on shallow land. When they start to drive the tanker again, they can put a hole in the tanker causing it to leak oil.

Deepwater oil spills have been closely monitored by many government and non government bodies. They have been observing response, assessment and restoration effects as well. There are long term and short term effects of the spill on the ecosystem and the marine life.

The deepwater spill in Gulf of Mexico and a spill after that, released almost 5 m barrels of crude oil in the Gulf of Mexico region. This caused extensive damage to coastal ecosystem.

The basic damage that these oil spills cause are those caused to the marine fish like whales that eat the oil or it enters through their blowhole.  The fish get poisoned and die. Also small organisms like plankton, larval fish, seaweed, oysters are affected because of deepwater oils spills. The fish cannot eat the plankton, so in turn they die. This disrupts the entire marine ecosystem and also endangers that species of fish.

The oil spills have been affecting the fish and aquatic invertebrates (including the oysters and shrimps). The oil affects through surface exposure, ingestion, absorption in the short term. In the long term their entire ecosystem is disturbed.

When exposed to the oil, eggs and larvae of many species are killed. This lowers the spawning success of the species. Even when the species survives the exposure, they lose their ability to fight away disease. Other problems that occur in the marine fish are:

  • Fin erosion
  • Increased heart rate
  • Enlarged livers
  • Other physical effects.


Some of the endangered species are:

  • Sharks
  • Blue crabs
  • Oysters
  • Shrimps
  • Yellow fin tuna
  • Blue tuna

There are many other endangered species due to the oil spills. The Gulf of Mexico spill was the biggest oil spill which caused main damage to the marine lives. Some of the other mammal species in trouble are:

  • Killer whale
  • Sperm whale
  • Spinner dolphin
  • Melon headed whale
  • Rough toothed dolphin

These are a few names. In all there are about 21 fish species endangered. The potential effects of oil spills are initially manifested at the individual level. The effects may be of the direct kind, which are related to contact with oil or dispersants, interactions with response activities. There are indirect effects too which are degradation of habitat and reduced availability of prey. Apart from the direct and indirect effects there are potential physiological or as we say behavioural effects. Some of them are:

  • Injury, lesions, disease, or death because of external or internal contact
  • Disturbance of social association
  • Physiological dysfunction of the some of the crucial systems like the immune or reproductive system
  • Prey displacement or reduced prey/ seagrass availability through or reduction in biomass of prey/seagrass
  • Injury from response activities, such as vessel strikes or other response equipment, or even from noise introduced in the marine environment
  • Reduction in status involving individual fitness, population vital rates (reproduction and survival rates), and/or population abundance and tendencies.
  • Disturbance or disruption of important biological behaviours, including foraging, reproduction, or resting.
  • Dislocation from primary habitat
  • When the ecosystem changes it becomes harmful to marine mammals thru hypoxia or anoxia or harmful algal blooms


The information that is available from sources observes effects of exposure of these oil spills on mammal and non mammal marine species. The deepwater oil spill exposure can also result in:

  • In case of ingestion of oil, gastrointestinal inflammation like ulcers, bleeding or mal digestion is possible
  • Inhalation of certain volatile organics leads to respiratory inflammation or irritation.
  • Noise from seismic surveys or other response-related activities may root to displacement, hearing loss which might be temporary or permanent and even other physical injury to marine fish.
  • Oil mixtures can foul the baleen of whale fish which is used for filtering food.
  • Some inhaled or ingested chemical from the oil damage organs like kidney, adrenal glands, spleen, brain damage and can cancer too.
  • Chemical contact may cause skin and eye irritation or burns to mucous membranes, mouth and lead to increased vulnerability to infection
  • Oil spills may modify the marine environment also.

Government and also many non government groups are taking initiative to understand the effect of these oil spills. The assessment of the deepwater oil spills are being done to understand the depth of the damage done to the marine life as well as the coastal regions.  The research strategies are being developed to minimize the effects of the oil spills. Restoration activities in the marine regions affected by oil spills have also begun.

Greener Ideal is an independent environmental news and lifestyle publication that has been curating content since 2008 to further the green movement. The views expressed by contributing authors are their own and may not reflect those of Greener Ideal.