World Fish Migration Day (WFMD) is celebrated every other year to raise global attention to the need for restored river connections for migrating fish to achieve healthier fish stocks and more productive rivers. The 4th and last World Fish Migration Day took place on 24 October 2020. The next one will take place on 22 May 2022.

What is a Migratory Fish?

Migratory fishes are fishes that swim short or long distances daily, or annually, as a way to complete their life cycle, feed and/or make love!

Creating awareness is an essential first step to make real change. The main goal of World Fish Migration Day is to improve the public's understanding of the importance of migratory fish and how we can reduce our impact on them. The next step is to enable citizens on the world to act on these topics. Ultimately, the aim is to create sustainable commitments from NGOs, governments and industry on safeguarding free rivers and restoring swim ways or migratory fish.

What is World Fish Migration Day?

World Fish Migration Day is a one-day global celebration to create awareness of open rivers and migratory fish. This international day of events is coordinated On World Fish Migration Day, organizations from around the world coordinate their own event around the common theme of: CONNECTING FISH, RIVERS AND PEOPLE. 

Fish migration is essential for healthy rivers.

Migratory fish all over the world depend on free-flowing rivers. Today, river barriers like dams, sluices and many other obstacles threaten many fish species' survival. Free flowing rivers, that allow fish to travel upriver, increase fish populations in the river and assure healthy river life. 

Factors like physical, chemical and biological factors influence the migrations in fishes. Physical factors like depth of water, temperature, light penetration, photoperiod, turbidity, velocity of current may cause migration. Chemical factors like pH and salinity.

Climate change affects all life on Earth, but it poses unique challenges for aquatic species. For example, as water warms it holds less dissolved oxygen than cooler water. As a result, the world’s oceans, coastal seas, estuaries, rivers and lakes are undergoing a process known as “deoxygenation.”

When dissolved oxygen levels fall to about 2 milligrams per liter – compared to a normal range of roughly 5 to 10 mg/L – many aquatic organisms become severely stressed. Scientists call this low oxygen threshold “hypoxia.”

Globally fisheries generate US$362 billion annually. Scientists are already forecasting loss of fish biomass due to warming water. But can we measure effects on fish directly?

For some climate change impacts, the answer is yes. Increasingly, a window on the secret lives of fishes is opening up through study of tiny, calcified formations inside fish skulls called otoliths – literally, “ear-stones.”

The ocean and climate change

·         The ocean is being disproportionately impacted by increasing carbon dioxide (CO2) and other greenhouse gas emissions (GHG) from human activities.

·         This causes changes in water temperature, ocean acidification and deoxygenation, leading to changes in oceanic circulation and chemistry, rising sea levels, increased storm intensity, as well as changes in the diversity and abundance of marine species.

·         Degradation of coastal and marine ecosystems threatens the physical, economic and food security of local communities, as well as resources for global businesses.

·         Climate change weakens the ability of the ocean and coasts to provide critical ecosystem services such as food, carbon storage, oxygen generation, as well as to support nature-based solutions to climate change adaptation.

·         The sustainable management, conservation and restoration of coastal and marine ecosystems are vital to support the continued provision of ecosystem services on which people depend. A low carbon emissions trajectory is indispensable to preserve the health of the ocean

 

Climate change is having a profound impact on our oceans and marine life. Its effects are changing the distribution of fish stocks and their food.

Balancing economic and environmental priorities is now even more important to keep our oceans healthy and full of fish for the future - we can only do this by fishing sustainably.  

93%of heat accumulated in the Earth’s atmosphere is absorbed by the oceans. Oceans play a major role in climate dynamics, absorbing 93% of heat that accumulates in the Earth’s atmosphere, and a quarter of the carbon dioxide (CO2) released from fossil fuels. The impacts of climate change on our oceans include shifts in temperature, acidification, deoxygenation and changes in ocean currents.

Given their importance to the planet, it's vital we manage the oceans in a sustainable way. Changes to the ocean mean changes to fish stocks. To manage fishing sustainably requires adapting to whatever issues climate change brings.

In the past 30 years, marine heatwaves are estimated to have increased by more than 50%. Globally, ocean temperatures are predicted to increase by 1-4°C by 2100.

These changes are impacting marine life. Sudden rises in temperature and acidification can lead to the loss of marine habitats and species. Shifting ocean currents and warming waters are changing the distribution of fish stocks and altering the structure of ecosystems.

How does climate change affect fishing?

Climate change threatens fish stocks, but also creates new opportunities for fishing.

Areas in the Tropics are predicted to see declines of up to 40% in potential seafood catch by 2050.

In contrast, areas in higher latitudes, such as the North Atlantic and North Pacific, are seeing increases in the range of some fish species.

These changes bring challenges. To continue to fish sustainably requires adopting new ways of fishing. The fishing industry and governments have found it difficult to agree how best to manage changing fish stocks, particularly if fish are moving across international boundaries or where catches need to be significantly reduced.

About the Author: Sidra Sarwer is an Environmental Science student at GCWUS, who has a keen passion for environment and climate.