Although there is much more to learn, oceanographers have already made some amazing discoveries. For example, we know that the ocean contains towering mountain ranges and deep canyons, known as trenches, just like those on land. The peak of the world’s tallest mountain—Mount Everest in the Himalayas, measuring 8.84 kms (5.49 miles) high—would not even break the surface of the water if it was placed in the Pacific Ocean’s Mariana Trench or Philippine Trench, two of the deepest parts of the ocean. On the other hand, the Atlantic Ocean is relatively shallow because large parts of its seafloor are made up of continental shelves—parts of the continents that extend far out into the ocean. The average depth of the entire ocean is 3,720 meters (12,200 feet).

It is unknown how many different species call the ocean their home, with so many marine ecosystems suffering from rising sea temperatures, overfishing,  pollution, and other problems.

Of all the threats facing the oceans today, overfishing takes the greatest toll on sea life — and people.

What is Overfishing?

Our world is a unique environment, in that every living being, plant, and landscape contributes to the overall wellness of the Earth. This is why the harmful effects of human waste, production, and consumption can have drastic effects on certain ecologies and biospheres. A major concern right now is the problem of overfishing. Ocean overfishing simply means catching fish from the sea at rates too high where fish stocks become too depleted to recover. With oceans taking up over 70% of the Earth, sea creatures, and the overall health of marine life is essential for sustaining life elsewhere on the planet, but overfishing is having drastic effects on the future of both ocean and land dwellers.

Causes of Overfishing

Put simply, overfishing occurs when more fish are caught then are able to reproduce to repopulate. Because fishing has long been an industry used by humans, there are a number of reasons why it is a problem today. Some of the causes of overfishing include:

• Difficulties in regulating fishing areas due to lack of resources and tracking activity.
• Most areas in the world have a total lack of oversight related to their fishing industry, which means the practices and activities of fishing fleets are not or barely monitored.
• In international waters, there are little to no rules regarding fishing practices, which means fishing fleets can bypass areas that do have regulations.
• Lack of knowledge regarding fish populations and quotas in a universal standard.
• Problems with customs and importation where the provenance of fish is not questioned, leading to surreptitious practices such as calling one kind of fish something else.
• Unreported fishing, which is nearly impossible to track.
• Many countries have subsidies for fishermen which keeps their number higher than it needs to be (it is estimated that there are 2 ½ times more fleets than needed).
• Fishing areas are largely unprotected – only a little over 1.5% of oceans have been declared protective areas, and most of these are still open to fishermen. This means that areas can be harmed or depleted.

Effects of Overfishing

Current estimates are that overfishing has impacted over 85% of the world’s fish resources and that most fisheries are fished far beyond their sustainable capacity. While this is poised to have long-term effects on human consumption, there are also a number of other effects, such as:

1. Removal of Essential Predators

Sharks and tuna are particularly susceptible to overfishing, and when they are removed from the areas they live in, this means that sea creatures further down the food chain are negatively impacted. Populations can grow larger, and the role that these larger creatures play – from what they eat to how their bodies decompose – mean potentially fatal effects for ocean ecosystems.

2. Poor Coral Reef Health

With a larger amount of smaller marine creatures comes greater damage to coral reefs and other elements of the ocean’s ecosystem. Reefs are essential to ocean life, and once they are harmed, it is hard to repair the damage, if at all.

3. Growth of Algae

In controlled amounts, algae are essential to helping marine life thrive, but if it is allowed to grow at will, it can impact fish, reefs, and more, leading to serious destruction.

4. Unintended Catches

Another concern of overfishing is that because the industry is so large, there are a number of sea creatures who get caught in the process, but don’t get used for food. This can mean everything from dolphins to turtles can be impacted by the presence of fishing fleets.

5. The Threat to Local Food Sources

There are a number of communities around the world that rely on fish as their primary resource for food. The growth of overfishing has caused a serious threat to these communities, which are often located in developing countries. Without the ability to catch their food, their populations are threatened.

6. Financial Losses

A lot of these communities that rely on fish for food also rely on low-level fishing industries for economic viability. These enterprises, as opposed to large-scale fishing ones, typically do far less damage to their marine life because they are on a much smaller scale. However, when these communities can’t access food or their financial support, they are likely to have trouble in the future.

7. An Utter Imbalance of the Marine Ecosystems

As has been pointed out earlier, overfishing has a very detrimental effect on marine ecosystems. The situations can be so bad that the fishes might not be able to sustain themselves any longer.

Also, when a particular species of fish is caught repeatedly and in an unchecked manner, the food chain of the water body is affected too. As a result of that, many other species of fishes dependent on that one particular species suffers due to the lack of food and dies.

8. The Targeted Fish and its Harvest

The demand for fish increases with an increase in the population. Also, as it happens, a few species of fishes have a higher demand than the others. This makes them the targeted fish species.

While it serves the economy well, it is because of the targeted fish that the marine ecological systems suffer a lot. Unchecked and unregulated harvest of the targeted species can render the water body “fruitless” due to this lack of ecological balance.

9. Rise of the Endangered Species

We must remember that with the rise of the targeted species, another category of species grows too. These are the untargeted species that soon turn into endangered species. This happens because of the prevailing ecological imbalance and also because proper efforts are not put in place to increase their population in a water body.

10. Improper Aquaculture

In order to be able to reinforce proper ecological balance in the water bodies, it is essential that the fisheries are equipped with not just the proper instruments but also the proper scientific knowledge to be able to practice proper aquaculture. Due to this lack of proper scientific knowledge, the aquaculture practices are vastly improper.

Obviously, another huge concern with overfishing is the damage it does to parts of the Earth that rely on healthy marine life. The problem is, unfortunately, so widespread that effects can be felt in every part of the world. 

Solutions to Overfishing

Clearly, the effects of overfishing are vast, and many of them won’t be known until they are actually negatively impacting human life on the planet. There are a number of conservation groups around the world focusing on ways to make the fishing industry more sustainable in the long run. Some of the solutions being used include:

1.Working With Governments

The lack of regulations and specific policy, and the fact that fishing has been an industry tied to the history of humans and civilization, many groups, like the World Wildlife Fund, are helping countries learn to prepare adequate and effective management protocols.

2.Reducing Subsidies

Many governments subsidize the fishing industry with subsidies, in an effort to keep the industry thriving. The problem with this is that it incentivizes fishermen to continue to expand, which means that subsidies only end up contributing to the problem of overfishing.

3. Create more Marine Protected Areas

Currently, less than 2% of the world’s oceans are protected in marine parks; and less than 1% of the oceans are protected from any kind of fishing. More no-catch zones must be established to allow fish populations and their ecosystems to recover and replenish themselves to ensure fishing for future generations. At least 1/3 of all our Oceans needs to be protected!

4. Stop Trawling

Trawling drags huge nets through the ocean that scoop up every animal and the ecosystem in its pathway, resulting in massive wasteful by-catch – dead fish are returned to the sea because they weren’t the target fish. We don’t have that kind of sea life to waste. Though there are many programs that focus on decreasing by-catch, and worldwide there are small regions where bottom trawling is banned or limited, these measures aren’t enough. Trawling needs to be banned outright.

Facing depleted fish stocks with an imminent and complete collapse, the Chinese government imposed a trawling ban in Hong Kong’s waters that took effect in December 2012. They did this by buying fishing vessels fitted for trawling, and supporting deckhands who’d be affected by the reduced amount of fish caught. Bans like this in the waters of Alaska, Chile and elsewhere are being fought for by environmental organizations.

5. Educate people and spread the world about overfishing problem
6. Eat less fish, especially the big endangered species like:

Bigeye tuna

Bluefin tuna

Skipjack tuna

Yellowfin tuna

Albacore tuna

Salmon

Abalone (from Japan and China)

Atlantic and Pacific cod

Atlantic Halibut

Spiny lobster (from the Caribbean area)

Mahi Mahi (from central to south America)

Orange roughy

Atlantic sardines

Nearly 70 species of shark

Rockfish

Squid (from Asia)

Did you know that at least half of Earth’s oxygen comes from the ocean?

Scientists estimate that 50-80% of the oxygen production on Earth comes from the ocean. The majority of this production is from oceanic plankton — drifting plants, algae, and some bacteria that can photosynthesize – a process which converts carbon dioxide and sunlight into sugars the organism can use for energy .One particular species, Prochlorococcus, is the smallest photosynthetic organism on Earth. But this little bacteria produces up to 20 percent of the oxygen in our entire biosphere. That’s a higher percentage than all of the tropical rainforests on land combined. It’s important to remember that although the ocean produces at least 50% of the oxygen on Earth, roughly the same amount is consumed by marine life. Like animals on land, marine animals use oxygen to breathe, and both plants and animals use oxygen for cellular respiration. Oxygen is also consumed when dead plants and animals decay in the ocean.

The Coral Reefs around the world are Dying

Tropical coral reefs are the most diverse marine ecosystems on earth, giving shelter to thousands of animal species. Many millions of people depend on fisheries, tourism and coastal protection provided by healthy coral reefs. Yet today, coral reefs are dying at an alarming rate all around the globe.

Corals build the reef structure and provide the basis for a functioning coral reef ecosystem. Without corals, reefs will degrade and vanish within years. At present, coral reefs are facing multiple stresses such as pollution, overfishing, and, overall, the on-going climate change―consequently raising sea water temperatures and causing coral bleaching worldwide. As a result, over 50% of the world’s coral reefs have died in the last 30 years and up to 90% may die within the next century—very few pristine coral reefs still exist.

Altogether, coral reefs comprise an area of almost 300 000 km² and are estimated to have an economic value of US$100 000 – 600 000 per km², thus providing one of the most high-value ecosystems. Coral reefs are among the most complex ecosystems and are revealing the degraded status of coastal environments. Their alarming status represents the poor health of our oceans and if coral reefs disappear other marine realms will follow.

Corals have existed for more than 400 million years; yet stresses and changes from human activities are happening faster than their ability to adapt. Corals may not survive the intensity and swiftness of these ongoing changes. A matter of vital importance is sexual reproduction of corals; as it is for most species. Sexual reproduction maintains genetic diversity and, in turn, enables species to adapt to a naturally dynamic environment in the long-term. Corals under stress are likely to stop sexual reproduction, which puts their survival at risk.

Did you know that dumped fishing gear is biggest plastic polluter in ocean?

Fishing nets lost, abandoned or discarded at sea – also known as “ghost nets” – can continue killing indiscriminately for decades and decades, entangling or suffocating countless fish, sharks, whales, dolphins, sea turtles, seals and marine birds every year. An estimated 30% of the decline in some fish populations is a result of discarded fishing equipment, while more than 70% of marine animal entanglements involve abandoned plastic fishing nets.

More than 640,000 tonnes of nets, lines, pots and traps used in commercial fishing are dumped and discarded in the sea every year, the same weight as 55,000 double-decker buses. The report, which draws on the most up-to-date research on “ghost gear” polluting the oceans, calls for international action to stop the plastic pollution, which is deadly for marine wildlife.

One study found that as much as 70% (by weight) of macroplastics (in excess of 20cm) found floating on the surface of the ocean was fishing related.

A recent study of the “great Pacific garbage patch”, an area of plastic accumulation in the north Pacific, estimated that it contained 42,000 tonnes of mega plastics, of which 86% was fishing nets.

Another expedition to the south Pacific found an estimated 18 tonnes of plastic debris on a 2.5km stretch of beach on the uninhabited Henderson Island and it was reportedly accumulating at a rate of several thousand pieces per day. In a collection of 6 tonnes of garbage, an estimated 60% originated from industrial fisheries.