fish stocks

Marine Heatwaves And Fish | Earth Wise

November 4, 2021 By EarthWise Leave a Comment

Marine heatwaves are periods of abnormally high temperatures in the ocean that can trigger devastating impacts on ecosystems, including coral bleaching, toxic algal blooms, and mass mortality events. Marine heatwaves can occur in any ocean and in any season. They are defined based on the differences between actual and expected temperatures for the location and time of year.

According to several studies, even under moderate climate warming scenarios, oceans will experience more frequent and longer-lasting marine heatwaves in the years to come.

Researchers from the University of British Columbia’s Institute for the Oceans and Fisheries in Canada have found that extremely hot years will wipe out hundreds of thousands of tons of fish globally this century. These losses are in addition to the projected decreases to fish stocks from long-term climate change.

Under a worst-case scenario where no action is taken to curb greenhouse gas emissions, the research team’s model predicts a 6% drop in the amount of potential catches per year. In addition, the biomass (or amount of fish by weight) is projected to decrease in 77% of exploited species due to the extreme temperatures.

As a result of climate change and these extreme heat events, the research team projected that fisheries’ revenues would decrease by an average of 3% globally, and employment would fall by 2% globally – a loss of likely millions of jobs.

The research team says active fisheries management is critical. Catch quotas, for example, need to be adjusted in years when fish stocks are suffering from marine heat events. In severe cases, the fisheries may need to be shuttered in order to allow fish stocks to rebuild.

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Fevers are plaguing the oceans — and climate change is making them worse

Marine heatwaves could wipe out an extra six per cent of a country’s fish catches, costing millions their jobs

Photo, posted October 11, 2016, courtesy of Kahunapule Michael Johnson via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Helping Out Corals With Cool Water | Earth Wise

October 22, 2020 By EarthWise Leave a Comment

Coral bleaching is happening five times more frequently than it did forty years ago. Its increasing occurrence is a result of global warming which leads to marine heat waves – periods of higher ocean water temperatures. Heat stress on living coral animals causes them to expel the algae that live symbiotically within the coral structure. As the algae is expelled, the coral fades in color looking like it is bleached. Without its algae partner, the coral eventually dies.

Given the increasing occurrence of marine heat waves, scientists are seeking novel ways to decrease heat stress in corals. A new study by the Bermuda Institute of Ocean Science is investigating the use of artificial upwelling – the application of cooler, deep water – as a way to mitigate thermal stress on corals.

Upwelling is a natural process in the ocean in which winds push surface water away from a region – for example, a coastline – which then allows the uplift of deeper, colder waters to the surface. Because such deeper waters are typically rich in nutrients, upwelling is important for supporting many of the world’s important commercial fisheries. For this reason, artificial upwelling has sometimes been used to increase fish stocks in certain locations.

The new work placed coral colonies in aquaria in Bermuda and tested the effects of varying amounts and temperatures of deep cold-water pulses upon corals subjected to thermal stress. The results showed that even short intrusions of cooler deep water (less than two hours per day) can mitigate thermal stress in corals. The next steps are to find suitable parameters for artificial upwelling that maximize the benefits while minimizing potential harmful side effects on the corals and the ecosystems they support.

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Can pumping up cold water from deep within the ocean halt coral bleaching?

Photo, posted February 24, 2008, courtesy of Roderick Eime via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Recovering Marine Life By 2050 | Earth Wise

May 27, 2020 By EarthWise Leave a Comment

Marine life has faced challenges for a long time. There have been centuries of overfishing in many places and pollution of various types has been especially harmful in recent decades. But despite all of this, a new scientific review published in the journal Nature contends that marine life in the world’s oceans could be fully restored in as little as 30 years provided that aggressive conservation policies are adopted.

The research spotlights the strong resiliency of ocean animals and cites the successful recovery of a number of marine species, including humpback whales.

The study indicates that nations around the world must agree to designate 20 to 30 percent of the oceans as marine protected areas, institute sustainable fishing guidelines, and regulate pollution. These measures would not come cheaply. The estimated cost would be around $20 billion a year.

However, the report also estimates that the economic return on this investment would be tenfold and would create millions of new jobs. Rebuilding fish stocks and maintaining sustainable fishing policies could increase global profits of the seafood industry by over $50 billion a year. Conserving coastal wetlands could save the insurance industry more than $50 billion a year as well by reducing storm damage.

A major sticking point, however, is climate change. Climate change is increasing ocean temperatures and driving acidification. Unless these changes are brought under control, the restoration of marine life is not going to be successful. We have reached the point where it is within our power to choose between a future with a resilient and vibrant ocean or an irreversibly disrupted ocean. Whether we embrace that challenge remains to be seen.

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Marine Life Could Recover By 2050 With the Right Policies, Study Finds

Photo, posted April 20, 2012, courtesy of Matthias Hiltner via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

More Fake Fish News

November 20, 2017 By EarthWise Leave a Comment

There has been quite a bit of news in recent years about the mislabeling of fish sold in markets and restaurants. One study a few years ago concluded that 1/3 of fish sold is not what it is labeled to be. Much of the practice is economic fraud: substituting cheaper, easier-to-find fish for rarer, more valuable types. For example, the study found that fish sold as red snapper was almost always not what it claimed to be. But cheating paying customers is not the only problem associated with the misidentification of fish.

[Read more…] about More Fake Fish News

New Rules For Ocean Conservation

September 21, 2017 By EarthWise Leave a Comment

In a recent report to a United Nations ocean conference, scientists are warning that new rules are desperately needed to protect marine life in the open seas. That’s because more than 60% of the ocean has no conservation rules since it’s located outside national jurisdictions. The open ocean is at risk from climate change, over-fishing, deep sea mining, farm pollution, and plastics pollution.