Overfishing
Many marine scientists <a href="http://www.oceanconservancy.org/site/PageServer?pagename=issues_overfishing" target="_hplink">consider</a> overfishing to be the worst impact humans are having on the oceans. The Food and Agriculture Organization <a href="http://www.un.org/events/tenstories/06/story.asp?storyID=800" target="_hplink">estimates</a> that over 70% of the world’s fish species have been entirely exploited or depleted. By capturing fish faster than they can reproduce, we are harming entire ecosystems that interact with those species, from the food they eat to the predators that eat them. These losses make the ecosystems more <a href="http://explorations.ucsd.edu/biodiversity/" target="_hplink">vulnerable</a> to other disturbances, such as pollution. A complete overhaul of fishing policies, requiring global cooperation, is needed to achieve a sustainable system.
Irresponsible Fish Farming
Fish farming, or aquaculture, is the growing response to wild fish stocks rapidly depleting. While it sounds like a good idea in theory, it unfortunately has many negative consequences due to poorly managed operations. Nutrient and chemical pollution can occur easily in open-ocean operations when fish feed, excrement, and medication is released into the environment. Farmed fish accidentally released into wild populations can also have <a href="http://www.fao.org/fishery/topic/14894/en" target="_hplink">destructive effects</a>, such as loss of native stocks, disease transmission, and damaging changes in habitat. Unfortunately, the biggest hindrance to overcoming the challenges of an industry that supplies nearly <a href="http://www.greenfacts.org/en/fisheries/l-2/01-fisheries-production.htm#5" target="_hplink">50%</a> of the world’s fish food supply is that it currently remains relatively <a href="http://www.oceanconservancy.org/site/PageServer?pagename=issues_aquaculture" target="_hplink">unregulated</a>.
Ghost Fishing
Ghost fishing is an environmentally harmful issue caused when lost or discarded fishing gear continues to catch fish and other marine life. Often times, the traps trigger a chain-reaction problem when larger predators come to eat the smaller ones that have been ensnared, only to get tangled in the mess themselves. The issue of ghost fishing is <a href="http://www.fao.org/fishery/topic/14798/en" target="_hplink">most common</a> with passive gear that has been abandoned, and also poses a serious threat to other ocean vessels. Stray gear can be caught in the propeller of a boat, damaging or even disabling it. Many solutions have been offered, such as fishing gear made from biodegradable materials or incentives like the Republic of Korea’s <a href="http://marinedebris.noaa.gov/projects/koreajpa.html" target="_hplink">buy-back program</a>, which rewards fisherman for turning in old gear.
Garbage
This one is the most obvious. It’s astounding how much of our trash finds its way into the ocean. Animals become easily entangled and trapped in our garbage, and it can destroy delicate sea life like coral and sponges. In addition, sea turtles and dolphins often mistake plastic bags for their favorite foods, jellyfish and squids, <a href="http://www.oceanconservancy.org/site/PageServer?pagename=issues_debris" target="_hplink">choking them</a> or clogging their digestive system. If that’s not bad enough, hopefully the <a href="http://news.nationalgeographic.com/news/2009/07/090731-ocean-trash-pacific.html" target="_hplink">bigger-than-Texas trash vortex</a> in the Pacific Ocean and its <a href="http://news.nationalgeographic.com/news/2010/03/100302-new-ocean-trash-garbage-patch/" target="_hplink">smaller cousin</a> in the Atlantic will help serve as a wakeup call.
Acidification
The ocean absorbs as much as <a href="http://www.sciencedaily.com/releases/2008/05/080521105251.htm" target="_hplink">one third</a> of the CO2 emitted worldwide, which keeps us cooler but makes the ocean surface much more acidic. This has the effect of limiting calcium carbonate needed by coral, plankton, and other marine life that <a href="http://www.oceanconservancy.org/site/News2?news_iv_ctrl=-1&abbr=press_&page=NewsArticle&id=10341#OceanAcidifying" target="_hplink">use it</a> to build the skeletal frames and shells that protect them. Oceanic acidity has increased by <a href="http://en.wikipedia.org/wiki/Ocean_acidification" target="_hplink">25%</a> since the industrial revolution, and will eventually destroy much marine life if it increases at this rate.
Dead Zones
Dead zones are areas where the sea floor has little to no dissolved oxygen. These areas are often found at the mouths of large rivers, and are caused <a href="http://disc.sci.gsfc.nasa.gov/oceancolor/additional/science-focus/ocean-color/dead_zones.shtml" target="_hplink">primarily</a> by fertilizers that are being carried in the runoff. Unfortunately, the lack of oxygen kills many creatures and destroys entire habitats. At our current rate, dead zones will increase by <a href="http://www.nature.com/news/2008/081114/full/news.2008.1230.html" target="_hplink">50%</a> before the end of the century.
Mercury Pollution
Scientists <a href="http://www.environmentalhealthnews.org/ehs/news/ocean-mercury-increasing" target="_hplink">report</a> that our ocean’s mercury levels have risen over 30% the last 20 years, and will increase another 50% in the next few decades. Emissions from coal power plants are the <a href="http://www.nescaum.org/documents/rpt031104mercury.pdf/" target="_hplink">primary culprit</a>, dispensing poisonous mercury that works its way up the food chain, eventually coming to us through the fish we eat. This <a href="http://www8.nationalacademies.org/onpinews/newsitem.aspx?RecordID=9899" target="_hplink">neurotoxin</a> can alter brain development of fetuses and has been linked with learning problems.
Offshore Drilling
Offshore drilling continues to be a debate, but it’s clear that proceeding with oil production will only exacerbate the dilemmas of our oceans. The use of fossil fuels is the reason our oceans have been heating up and becoming more acidic, but offshore drilling takes the risks even further. When oil is extracted from the ocean floor, other chemicals like mercury, arsenic, and lead <a href="http://science.howstuffworks.com/offshore-drilling-controversy2.htm" target="_hplink">come up with it</a>. Also, the seismic waves used to find oil harm aquatic mammals and disorient whales. In 2008, <a href="http://www.livescience.com/environment/080625-oil-drilling.html" target="_hplink">100 whales</a> had beached themselves as a result of ExxonMobil exploring for oil with these techniques. Furthermore, the infrastructure projects to transport the oil often create <a href="http://www.treehugger.com/files/2009/02/offshore-drilling-oil-false-hope.php" target="_hplink">worse problems</a>, eroding the coastline. These realities are another reason
Shark Finning / Whaling
The destruction of the ocean’s most important predators has significant consequences that ripple down the food chain. 50 to 100 million sharks are killed <a href="http://www.hsus.org/hsi/oceans/sharks/shark_finning/" target="_hplink">each year</a>, either as bycatch from fishing vessels or directly hunted for their dorsal fins, used in an expensive soup popular across Asia. When finned, the sharks are thrown back into the water, often still alive and left to bleed to death. Unfortunately, sharks reproduce fairly <a href="http://www.treehugger.com/files/2007/01/jeanmichel_cous.php" target="_hplink">slowly</a> and don’t have a large amount of offspring, so these actions have long-lasting effects on the delicate ecosystems they help <a href="http://www.hsus.org/hsi/oceans/sharks/shark_finning/shark_finning_faq.html" target="_hplink">regulate</a>. Despite the 1986 moratorium on many types of whaling, it still continues to be a problem, with some nations like Japan looking for loopholes and lobbying for lax regulations.
Loading comments… 
Huffington Post Travis Walter Donovan First Posted: 05/29/10 06:12 AM ET Updated: 05/25/11 04:55 PM ET