Overview: Marine Biodiversity, Over fishing, and Sustainable Fishing

This article is about Marine Biodiversity and Over-fishing. In the 20th C, fresh water fish have the highest death rate worldwide among bony fish. Almost 6 billion tons of fish and sea food have been taken from the world’s oceans since 1950. We must ensure the world’s fisheries and oceans are productive and resilient.  So it is necessary to lock in jobs and have biodiversity. We must also ensure fresh waters provide water for people and nature.

Source: wwf.panda.org/knowledge_hub/all_publications/living_planet_report_2018/

What is Biodiversity?

Biodiversity is the sum of all the mix of species of animals, plants, fungi and microbes living on Earth.  It also includes the zones where they live. Scientists estimate that more than 10 million species live on Earth.

Biodiversity supports much, from food production to medical research. Humans use about 40,000 species of plants and animals daily. Many people around the world still use wild species for some or all of their food, shelter, and clothing.  All our plants and animals came from wild living native species.  Further, almost 40 percent of the drugs used in the United States either are based on or are made from natural compounds.

Source: www.aboutbioscience.org/topics/biodiversity/

What is the difference between Marine Biodiversity and Biodiversity?

Marine biodiversity refers to the species richness and extent in the world’s oceans. Since the world is covered with about 70% water, the range of life in the oceans is huge. ‘Biodiversity’ means the mix among living animals from all sources, and their ecology.  Further, this mix is within and between species, and of ecosystems.

Source: Google

See also: science.sciencemag.org/content/314/5800/787

What is a sustainable fishery?

One idea of a sustainable fishery is that it is harvested at a even rate. The fish pool does not shrink over time because of fishing methods. Sustainability in fisheries combines the  study of populations with practical methods.  These include avoiding over fishing through methods such as counting individual fish. Also, they include ending illegal fishing practices by lobbying.  These also include restoring collapsed fisheries.  Finally, there are training and certification programs for the wider public.

There are some concerns.  These are that heavy fishing pressures, such as overuse will result in the loss of stable yield. The stock structure will erode to the point where it loses diversity and resilience to environmental changes. Ecosystems and the economy will cycle between collapse and recovery; with each cycle yielding less than the one before it. And, changes occur in the ocean food webs.

Source:  Hilborn, Ray (2005) “Are Sustainable Fisheries Achievable?”

See also – en.wikipedia.org/wiki/Sustainable_fishery

What type of fish are in the ocean?

Fish that live in the ocean can be carnivores, herbivores, or omnivores. Many herbivores’ diets consist of mostly algae. Most saltwater fish will eat both large and small algae.  Most saltwater fish that are carnivores will never eat algae under any condition.  Carnivores’ diets are shrimp, plankton, or tiny crustaceans.

Fish classification includes:

  • First, Coastal fish inhabit the sea between the shoreline and the edge of the shelf.
  • Second, Deep sea fish live below the zone of the ocean where not enough light beams for photosynthesis to occur.
  • Third, Surface fish live near the surface of the sea or lake.
  • Fourth, Bottom fish live on or near the bottom of the sea or lake.
  • Lastly, Coral reef fish are around a coral reef.

Source: Bale, Rachael (2016-05-03). “Breeding Aquarium Fish Can Help Save Reefs”. National Geographic.

What is over fishing?

Whale sharks, the largest species of fish, are at risk.

Over fishing is a major threat to edible fish such as cod and tuna. Over fishing eventually causes population (known as stock) collapse because the survivors cannot produce enough young to replace those removed.  Such extinction does not mean that the species is gone, merely that it can no longer sustain a fishery.

One example of fishery collapse is a Pacific sardine fishery off the California coast. From 1937 to 1968 the catch tonnage slowly declined,  then the fishery was no longer viable.

There is much tension between science and the industry. The two groups have different views on the resiliency of fisheries to intensive fishing. In places such as Scotland, Newfoundland, and Alaska the industry is a major employer, so governments support it. On the other hand, scientists push for strict protection, warning that many stocks could end within fifty years.

Source: See wikipedia entry on “Fish”

What is habitat loss?

A key stress on both freshwater and marine zones is habitat loss.  These include water pollution and the building of dams. Humans need water, and the introduction of exotics are also factors. An example of a fish that has become endangered because of zone change is the pallid sturgeon, a North American freshwater fish that lives in rivers damaged by human use.

Source: see Wikipedia entry on “Fish”

What is catch and release?

Catch and release is used in recreational fishing.  It is a way of conservation. After capture, the fish are unhooked and returned to the water. Often, a fast assay and weighing of the fish is worthwhile. Using barb less hooks, it is possible to release the fish without removing them from the water.

Source: https://en.wikipedia.org/wiki/Catch_and_release

What are the fishing techniques?

Fishing techniques are methods for catching fish. The term may also be applied to methods for catching other aquatic animals such as mollusks (shellfish, octopus) and edible marine fish without bones.

Fishing techniques include hand gathering, spearfishing and netting. Angling and trapping are others.  Recreational, commercial and artisanal fishers use the same or different methods. Recreational fishers fish for pleasure or sport. Commercial fishers fish for profit. Artisanal fishers use older, low tech ways.  This is for survival in third world countries, and as a cultural heritage in others. Moreover, Recreational fishers use angling methods. Commercial fishers use netting methods.

Finally, there is a link between fishing techniques and knowledge about the fish and their behavior.  This includes migration, foraging and habitat. The good use of fishing techniques often depends on this added knowledge. The species and its’ zone dictate when to use which technique.

Fishing techniques can be contrasted with fishing tackle. Fishing tackle refers to the physical equipment  used when fishing, whereas fishing techniques refers to the way in which the tackle is used when fishing.


What are some unsustainable fishing methods?

Unsustainable fishing methods are ways of catching wild fish that are not considered sustainable in the long term. This could be because they threaten the stock itself by over fishing, or because they threaten the environment the fish need to thrive. Dynamite fishing, e l e c t r o fishing, or fishing with poisons are examples of the latter, used in newer areas.

Western unsustainable fishing includes bottom trawling, which was called a ‘great harm’ by a group of leading marine environments.

Fish stocks are reduced by illegal and unreported fishing, and these hurt the fish pool.  It is believed that 10 billion to 23 billion incidences happen yearly. Further, newer countries are more likely to be at risk for illegal actions.

Although countries have tried to control blast fishing, it is still used in poor parts of the world.  Blast fishing is a sight. The water is strewn with dead  or struggling fish.

Source: https://en.wikipedia.org/wiki/Unsustainable_fishing_methods

So, what political and economic and social means have been used with fishing?

Fishers are also joining forces with farmers, pastoralists, rural, and native peoples. Overlapping food and climate crises create common bonds between social movements.

Their shared pledge to creating a fair food system has led to a global web of agrarian, climate, and environmental justice movements. Also, there is the coming of what could be a global ‘fisheries justice’ movement.

Key is the World Forum of Fisher Peoples

Founded in 1997, the WFFP now links 43 national small fishers’ groups.  These are in 40 countries around the world. It looks at the issues that small fisheries have (e.g. privatization, climate change).  They also fight for fishers’ human rights and to lock in jobs.

Source: https://theecologist.org/2018/sep/10/transformation-and-resistance-global-fisheries-sector

What is the latest in the fishing plight in the EU?

The main message of this report is that rising eating of  fish in a context of overused stocks is not viable and is socially unfair. The EU has highly productive waters.  These have the means to sustain a long term and stable supply of fish, jobs and related social and economic pluses. That is, only if its’ fish wealth is managed well. We have started to see some signs in fish stocks recovery but are still very far from where we should be. Nearly half of European stocks are still depleted.

Source: https://neweconomics.org/2017/03/fish-dependence-2017-update/?_sft_latest=research

What are protected areas and would they help?

Useful as they are, marine reserves – often near points like coral reefs or rock isles – are only good if governments have the means to patrol and protect them. Also, many marine creatures, from whale sharks to whales don’t stay in the protected areas.  So they are easy prey for fishers. What’s needed, many argue, are mobile reserves that follow migratory animals. Also those that shift habitat due to currents or climate changes like El Nino.

The zones need to be well targeted and need not impact fisher’s jobs. For example, one study found that designating just 20 sites – 4% of the world’s oceans – as conservation zones could protect 108 species –84% of the world’s marine mammals.



“In the end, we will conserve only what we love. We will love only what we understand. And we will understand only what we are taught.”

– Conservationist Baba Dioum


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Stephen Saunders

Executive Director, Long Term Economy | Member, LTE International Board | Auditor

Stephen Saunders has 25 posts and counting. See all posts by Stephen Saunders

Stephen Saunders

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