fishing

Climate Change And Crabs | Earth Wise

November 8, 2022 By EarthWise Leave a Comment

Globally, there are more than 6,000 species of crabs. In Alaska’s waters alone, there are 18 species, including 10 that are commercially fished. The perils of crab fishing in this region, including freezing temperatures, turbulent seas, and raising full pots that can weigh well over a ton, have been highlighted for many years in the reality TV series Deadliest Catch.

One of those commercially-fished species is the Alaska snow crab. Alaska snow crabs are a cold-water species found off the coast of Alaska in the Bering, Beaufort, and Chukchi Seas.

In October, officials in Alaska announced that the upcoming winter snow crab season would be canceled for the first time ever due to a sharp population decline. While the number of juvenile snow crabs was at record highs just a few years ago, approximately 90% of snow crabs mysteriously disappeared ahead of last season. Officials also canceled the Bristol Bay red king crab harvest for similar reasons for the second year in a row.

The closures dealt a severe blow to crab fishers in the region. According to the Alaska Seafood Marketing Institute, Alaska’s crab fishing industry is worth more than $200 million.

The canceled seasons also raise questions about the role of climate change in the snow crab population crash. While the causes of the decline are still being researched, scientists suspect that warmer temperatures are responsible. Temperatures in the Arctic region have warmed four times faster than the rest of the planet.

As the climate continues to change, the warming waters around Alaska may become increasingly inhospitable to snow crabs and other species.

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Alaska’s Bering snow crab, king crab seasons canceled

Alaska cancels snow crab season for first time after population collapses

Photo, posted November 16, 2010, courtesy of David Csepp / NOAA via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Pacific Bluefin Tuna On The Rebound | Earth Wise

September 21, 2022 By EarthWise Leave a Comment

The Pacific Bluefin Tuna is a commercially valuable species that is especially prized in Japan. The fish is particularly valued for sashimi and sushi and large specimens have been known to fetch enormous prices at seafood auctions.

Aggressive fishing reduced the bluefin biomass through the late 1990s and 2000s to only a few percent of its potential unfished levels. Beginning in 2011, The Western and Central Pacific Fisheries Commission began management measures that reduced the catch of smaller bluefin as well as limited the catch of larger bluefin. The goal was to allow more fish to grow to maturity. The Inter-American Tropical Tuna Commission adopted similar resolutions a year later. Despite these efforts, increasing concern about declining bluefin levels led to a petition to list the species as endangered. The National Oceanic and Atmospheric Administration’s Fisheries organization determined that while the population was near historical lows, the remaining 1.6 million fish was a sufficient number to avoid the risk of extinction and that the measures in place were sufficient.

A new assessment of the bluefin population has shown that the species is now increasing and includes many younger fish that will help accelerate its rebound. The assessment by NOAA showed that the bluefin stock was greater than the first rebuilding target set for 2019.

According to the NOAA Fisheries biologists that performed the assessment, the species has responded exactly as predicted given the actions that were taken. The bluefin tuna is an amazingly resilient fish and it is continuing to demonstrate that fact.

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International Actions Pay Off For Pacific Bluefin Tuna as Species Rebounds at Accelerating Rate

Photo, posted June 1, 2022, courtesy of Philippe Yuan via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Better Marine Protected Areas | Earth Wise

August 17, 2022 By EarthWise Leave a Comment

Marine protected areas are regions of seas, oceans, estuaries, and in the US, the Great Lakes, that are afforded special protections. MPAs restrict human activity for conservation purposes, generally in order to protect natural or possibly cultural resources. MPAs may limit such things as development, fishing practices, fishing seasons, catch limits, moorings, and removal or disruption of marine life.

A new study by the University of Plymouth in the UK looked at the effectiveness of MPAs in increasing the total abundance of reef species. It looked at the MPAs in Lyme Bay, off the south coast of England, where two of them are co-located but governed by different constraints.

The study found that whole-site management of an MPA can increase the total abundance of reef species within its borders by up to 95%. This is in contrast to the MPA where only known features are conserved and human activity is otherwise allowed to continue unchecked. In that place, species abundance increased by only 15%.

The whole-site MPAs were observed to have other benefits as well. They show higher levels of functional redundancy, meaning that when there are species losses, they are compensated by other species. Whole-site MPAs also exhibit higher levels of species diversity.

MPAs are increasingly being recognized as a sustainable way to enhance the marine environment even while supporting coastal communities. The Global Ocean Alliance, a 72-country alliance led by the UK, has set a target of protecting 30% of all marine areas by 2030. The new study shows that even more important than simply establishing marine protected areas, it is essential that they are effectively implemented.

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Whole-site management of Marine Protected Areas can lead to a 95% increase in reef species

Photo, posted October 28, 2011, courtesy of Benjamin Evans via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Shipping And The Endangered Whale Shark | Earth Wise

June 9, 2022 By EarthWise Leave a Comment

Whale sharks are the largest fish in the world. While they measure up to 60 feet long and weigh up to 15 tons – larger and heavier than a school bus – whale sharks are actually harmless. They are a graceful, slow-moving, filter-feeding carpet shark. They are found in marine environments around the world and play an important role in the marine food web and healthy ocean ecosystems.

Whale sharks are an endangered species. According to the International Union for Conservation of Nature, growing human pressures are putting whale sharks at an increased risk of extinction. The numbers of these gentle giants have declined by more than 50% over the last 75 years despite many international protections. Fishing bycatch, poaching, and collisions with ships are the main drivers of the population decline.

According to new research from marine biologists from the Marine Biological Association and the University of Southampton in the U.K., lethal collisions between whale sharks and large ships are vastly underestimated, and could be the reason why populations are continuing to fall. Whale sharks spend a large amount of time in surface waters in coastal regions, and the research team theorized that collisions with ships could be causing significant whale shark deaths.

In the study, researchers tracked the global movements of both ships and whale sharks, and then mapped so-called hotspots where their movements overlapped. The research team found that more than 90% of whale shark movements fell under the footprint of shipping activity.

While many conservation measures have been taken to protect whale sharks, no international regulations currently exist to protect them from ship collisions. The researchers say it’s time for that to change.

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Shipping poses significant threat to the endangered whale shark

Whale sharks (Rhincodon typus)

Global collision-risk hotspots of marine traffic and the world’s largest fish

Photo, posted July 8, 2010, courtesy of Marcel Ekker via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Is It Too Late To Save The Vaquita? | Earth Wise

June 6, 2022 By EarthWise Leave a Comment

The vaquita porpoise, the world’s smallest marine mammal, is on the brink of extinction. Scientists estimate that just 10 or fewer vaquitas are left despite international conservation efforts. Found only in Mexico’s Upper Gulf of California, the vaquita is the most endangered marine mammal on the planet.

According to the International Committee for the Recovery of the Vaquita, the number one threat facing vaquitas is gillnets. The porpoises get trapped in these nets and drown. Gillnets are often used illegally in the region to catch shrimp and fish, including the critically-endangered totoaba. The totoaba’s swim bladder is considered a delicacy in Asia and can fetch thousands of dollars. Despite Mexico banning both totoaba fishing and the use of gillnets in the vaquitas’ habitat, many say the bans are not always enforced.

But there is a reason to be hopeful. According to a genetic analysis led by researchers at UCLA, the critically-endangered species actually remains relatively healthy and can potentially survive if illegal fishing practices cease immediately.

In the study, which was recently published in the journal Science, the research team analyzed the genomes of 20 vaquitas between 1985 and 2017 and ran simulations to predict the species’ extinction risk over the next 50 years. The researchers concluded that if gillnet fishing ends immediately, the vaquita has a very high chance of recovery. If the practice continues, however, even moderately, the likelihood of a recovery plummets.

According to the research team, the surviving vaquitas are actively reproducing and seem healthy. But poachers’ gillnets will continue to pose an existential threat to the species until more measures are taken to protect the vaquita.

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Only 10 vaquita porpoises survive, but species may not be doomed, scientists say

Photo, posted October 18, 2008, courtesy of Paul Olson / NOAA via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Assessing Human-Caused Wildlife Mortality | Earth Wise

May 31, 2022 By EarthWise Leave a Comment

Bycatch is the fishing industry term used to describe the deaths of non-target fish and ocean wildlife during the fishing process. Some bycatch species are thrown away because regulations prohibit them from being kept. Others are thrown out because they won’t fetch high enough prices. According to some estimates, global bycatch amounts to about 10% of the world’s total catch.

Approximately half of global bycatch is a result of trawling. Trawling is a method of commercial fishing that involves pulling or dragging a fishing net – called a trawl – through the water or across the seabed in hopes of catching fish. Commercial fishing companies favor towing trawl nets because large quantities of fish can be caught. But the method is destructive to the seafloor and leads to the indiscriminate catch of all sorts of species, including whales, dolphins, porpoises, sharks, seals, rays, turtles, and seabirds.

Researchers have developed a new method to assess the sustainable levels of human-caused wildlife mortality. When this method is applied to a trawl fishery in Australia, it shows that the dolphin capture is not sustainable. The study, led by scientists at the University of Bristol in the U.K. and United Arab Emirates University, modeled different levels of dolphin capture, including those reported in logbooks and those reported by independent observers. According to the findings, which were recently published in the journal Conservation Biology, even the lowest recorded dolphin capture rates are not sustainable.

The new approach is extremely adept at assessing human-caused mortality to wildlife, and can be applied to fisheries bycatch, hunting, lethal control measures, or even wind turbine collisions.

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Wasted Catch

Dolphin bycatch from fishing practices unsustainable, study finds

Photo, posted May 18, 2011, courtesy of Pete Markham via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Invasive Species On Ships In Antarctica | Earth Wise

February 23, 2022 By EarthWise Leave a Comment

The Southern Ocean around Antarctica is the most isolated marine environment on Earth. Antarctica’s native species have been isolated for the last 15-30 million years. As a result, wildlife there has not evolved the ability to tolerate the presence of many groups of species.

New research by the University of Cambridge and the British Antarctic Survey has traced the global movements of all the ships entering Antarctic water and has found that Antarctica is connected to all regions of the globe via ship activity to an extent much greater than previously thought. Fishing, tourism, research, and supply ships are exposing Antarctica to invasive, non-native species that threaten the existing ecosystems.

In all, the research identified over 1,500 ports with links to Antarctica. From all these places, non-native species including mussels, barnacles, crabs, and algae attach themselves to ships’ hulls. The process is known as biofouling.

The greatest concern is the movement of species from pole to pole. These species are already cold-adapted. They may come on tourist or research vessels that spend the northern hemisphere summer in the Arctic before traveling south for the Antarctic summer season.

Mussels have no competitors in Antarctica should they be accidentally introduced. Shallow water crabs would introduce a new form of predation that Antarctic animals have never encountered before.

Current biosecurity measures to protect Antarctica, such as cleaning ships’ hulls, focus on a small group of so-called gateway ports. The new findings indicate that these measures need to be expanded to protect Antarctic waters from non-native species.

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Invasive species ‘hitchhiking’ on ships threaten Antarctica’s unique ecosystems

Photo, posted April 12, 2016, courtesy of NOAA’s National Ocean Service via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Right Whales And The Warming Atlantic | Earth Wise

October 25, 2021 By EarthWise Leave a Comment

The warming of the Atlantic Ocean has driven the critically endangered North Atlantic right whale population from its traditional and protected habitat. This has exposed the whales to more lethal ship collisions, increased entanglements with commercial fishing gear, and greatly reduced calving rates.

Since 2010, the calving rate has declined, and the right whale population has dropped by an estimated 26%. Ten years ago, there were about 500 North Atlantic right whales; now there are an estimated 356.

These are some of the best studied whales in the oceans; scientists basically recognize each individual whale and when they are the victims of ship collisions or fishing entanglements, it is easy to identify which animal was killed.

Because of the warming climate, the Atlantic Meridian Overturning Circulation – an important system of surface and deep currents – has slowed down, causing the Gulf Stream to move north. This has injected warmer and saltier water into the Gulf of Maine. The warming Gulf of Maine has reduced the abundance of copepods, tiny crustations that are the favorite snack of right whales. This has reduced whale calving rates and forced the whales to move north to the cooler waters of the Gulf of St. Lawrence.

For the past 6 years, more and more right whales have been observed feeding in the Gulf of St. Lawrence, where there were no protections in place to prevent ship strikes and fishing gear entanglement. In 2017 alone, 17 right whale deaths were confirmed.

According to a recent report from Cornell University and the University of South Carolina, unless its management is improved, right whale populations will decline and potentially become extinct in the coming decades.

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Warming Atlantic forces whales into new habitats, danger

Photo, posted December 8, 2016, courtesy of Sea to Shore Alliance/NOAA via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Climate Change And Kenya’s Tana River Basin | Earth Wise

September 6, 2021 By EarthWise Leave a Comment

The Tana River is the longest river and most important waterway in Kenya. It flows 620 miles from its headwaters in the Abderdare mountain range and Mount Kenya to the Indian Ocean. The Tana River produces approximately half of the country’s electricity, and supplies Nairobi, the capital of Kenya, with 80% of its water.

According to the United Nations Environment Programme, eight million people live along the Tana River, where coffee, tea, corn and other crops are grown for export, and fishing and cattle grazing help produce food for large portions of the country’s population.

But the long-term ability of the river to provide these and other essential services is increasingly under threat due to many factors, including pollution, soil erosion, deforestation, and poor land use practices.

Climate change is also complicating matters. According to new research from the University of East Anglia, many species within the Tana River Basin will be unable to survive if global temperatures continue to rise at the current pace. However, the study, which was recently published in the journal PLOS ONE, also found that many of these species could be saved if the world could meet the climate goals of the Paris Agreement.

Globally, climate and land use changes are the two biggest threats to biodiversity. According to researchers, 36% of the Tana River Basin has already been converted to agriculture.

The research team says stronger commitments on climate change are needed from global leaders. The climate and biodiversity crises can only be solved with urgent action to reduce global greenhouse gas emissions.

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The impact of climate change on Kenya’s Tana river basin

Economics of Ecosystem Services of the Tana River Basin

Photo, posted August 19, 2010, courtesy of Luigi Guarino via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Protecting The Ocean Has Multiple Benefits | Earth Wise

June 21, 2021 By EarthWise Leave a Comment

An international team of authors from 18 institutions has recently published a paper in the journal Nature that offers a solution that addresses several of humanity’s most pressing problems at the same time. The paper provides a comprehensive assessment of where strict ocean protection can contribute to a more abundant supply of healthy seafood, help address climate change, and protect embattled species and habitats.

The study identified specific areas of the ocean that could provide all of these benefits if they were protected. Currently, only about 7% of the ocean is under any kind of protection. According to the study, if the appropriate 30% of the ocean was protected by the actions of the relevant countries by 2030, the cited benefits would be realized.

Safeguarding these regions would protect nearly 80% of marine species while increasing fishing catches by almost 9 million tons a year. It would also prevent the release of more than 1 billion tons of carbon dioxide by protecting the seafloor from bottom trawling, which is a widespread and destructive fishing practice.

Ocean life has been declining worldwide because of overfishing, habitat destruction, and climate change. The study pioneers a new way to identify the places that – if protected – will boost food production and safeguard marine life, while at the same time reducing carbon emissions. The study finds that countries with large national waters and large industrial trawl fisheries have the highest potential to contribute to climate change mitigation by protecting the carbon stored on the ocean floor. The ocean covers 70% of the Earth and its importance in solving the challenges of our time must not be underestimated.

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Three Times the Gains

Photo, posted January 10, 2016, courtesy of Hafsteinn Robertsson via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Biodiversity And Trawling Bans | Earth Wise

June 7, 2021 By EarthWise Leave a Comment

Trawling is a method of commercial fishing that involves pulling or dragging a fishing net – called a trawl – through the water or across the seabed in hopes of catching fish. Commercial fishing companies favor towing trawl nets because large quantities of fish can be caught in one go.

However, the trouble with trawling is that it’s destructive to the seafloor and indiscriminate in what it catches. When towing these large trawl nets, the largest of which is reportedly big enough to catch thirteen 747 jets, everything that happens to be in the way gets caught. As a result, trawling results in lots of bycatch, a fishing industry term used to describe the deaths of non target species during the process.

In 2012, the Hong Kong government implemented a territory-wide trawling ban in its waters in hopes of rehabilitating the marine benthic habitat. The benthic zone refers to the ecological region at the bottom of the ocean.

Researchers from City University of Hong Kong collected sediment samples from 28 locations six months before the trawl ban and two and a half years after the trawl ban to see whether such interventions can facilitate ecosystem recovery.

According to the study, which was recently published in the journal Communications Biology, the ban on trawling significantly improved marine biodiversity. The researchers observed substantial increases in the richness of species and the abundance of benthic marine organisms following the trawling ban. And since small benthic organisms are the main source of food for large species like fish and crabs, the trawling ban actually helps support fisheries.

More governments should consider a trawl ban to promote sustainable fisheries and marine biodiversity conservation.

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Research confirms trawl ban substantially increases the abundance of marine organisms

Photo, posted December 4, 2018, courtesy of John via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Restoring Coastal Ecosystems | Earth Wise

February 1, 2021 By EarthWise Leave a Comment

Research published by CSIRO, Australia’s national science agency, examined the positive effects of restoration efforts for coastal ecosystems in terms of biodiversity, local economies, and human wellbeing.

Coastal ecosystems include saltmarshes, mangroves, seagrasses, oyster reefs, kelp beds, and coral reefs. All of these have suffered declines of up to 85% over recent decades. The research identified a number of successful coastal and marine restoration projects in recent years that indicate the likelihood that such efforts could be expanded by as much as a factor of ten to support human health and wellbeing, boost the adaptation response to climate change, and generate jobs.

Some of the successful efforts identified included projects in the Great Barrier Reef to harvest coral larvae to boost large-scale coral restoration efforts. Simple changes to how saltmarshes are planted have resulted in doubled survivorship and biomass. In the U.S., the propagation of seagrass seeds has resulted in seagrass meadows recovering in areas where they had been lost decades ago. In Indonesia, recovery of reefs impacted by blast fishing has been achieved by placing rocks or other hard structures underwater to help with coral colonization.

Investing in coral restoration creates jobs and can be used as a strategy to boost economic recovery and coastal marine health. Restoration of marine habitats like kelp forests and oyster reefs has improved commercial and recreational fishing.

The United Nations has recognized the importance of coastal restoration and has declared the Decade on Ecosystem Restoration to start from 2021.

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Scientists shine light on ‘bright spots’ to restore coastal ecosystems

Photo, posted November 29, 2012, courtesy of Robert Linsdell via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

The Costs Of Mislabeled Seafood | Earth Wise

January 27, 2021 By EarthWise Leave a Comment

Seafood is the world’s most highly traded food commodity and reports of seafood mislabeling have become increasingly common over time. A new study by Arizona State University looked at the environmental effects of mislabeled seafood.

What is mislabeled seafood? Sometimes the snapper you were served was really Pacific Ocean Perch. Maybe grouper was really whitefin weakfish. Many times white leg shrimp are actually giant tiger prawns.

Approximately 190,000 to 250,000 tons of mislabeled seafood are sold in the U.S. each year, or 3.4 to 4.3% of consumed seafood. Previous studies focused on the economic aspects of getting cheaper fish when paying for more expensive fish. The new research looks at the environmental costs associated with mislabeled seafood.

Substituted seafood is 28% more likely to be imported from other countries, which may have weaker environmental laws than the U.S. In the United States, fishery management is pretty good. There is strong monitoring and enforcement to support limits on fishing. Metrics like fish abundance, fishing mortality, bycatch, and discards are all monitored. In many other places, this is not the case.

To really evaluate the overall effects of seafood mislabeling, one has to take into account both the rates of substitution and the levels of consumption.

Consuming fish from a well-managed fishery should not have a negative impact in terms of the population now or in the future. But even inadvertently consuming fish from poorly managed fisheries in not sustainable. It is good to get your seafood from a trusted source.

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ASU Study Looks At The Environmental Effects Of Purchasing, Consuming Mislabeled Fish

Photo, posted August 1, 2014, courtesy of Ralph Daily via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

The Cost of Cleaning Up Ocean Plastic | Earth Wise

October 7, 2020 By EarthWise Leave a Comment

Small island developing states increasingly find themselves with large amounts of plastic waste. A recent study looked at the financial cost for removing it.

Aldabra Atoll is a UNESCO World Heritage Site in the Seychelles. It is the world’s second-largest coral atoll and is the home of 307 species of animals and plants, including the largest population of giant tortoises in the world. Aldabra has been called one of the wonders of the world and one of the crown jewels of the Indian Ocean.

Last year, a team from the University of Oxford and the Seychelles Island Foundation, spent five weeks removing litter that had washed up on Aldabra’s shores. In total, they removed 25 tons of plastic litter which, to their surprise, was dominated by waste from the fishing industry. The researchers now estimate that over 500 tons of litter remain on the island, 83% of which consists of buoys, ropes, nets, and, of all things, over 300,000 individual flipflops. This is the largest accumulation of plastic waste reported for any single island in the world.

According to the study, the cost to clean up the entire island would be nearly $5 million, requiring 18,000 person-hours of labor. A project of this magnitude is beyond the capacity of non-profit organizations like the Seychelles Islands Foundation.

The plastic pollution in Aldabra is related to the fishing industry in Seychelles, which provides tuna to high-income markets around the world. The research highlights how even remote highly protected island ecosystems are impacted by global pollution and how difficult and costly it is to remedy.

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Millions of dollars to clean up tuna nets and flip flops from island state

Photo, posted December 27, 2016, courtesy of David Stanley via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

A Giant Marine Preserve | Earth Wise

May 4, 2020 By EarthWise Leave a Comment

The Seychelles islands are located east of Kenya, near the equator. Its beautiful beaches, virgin jungles, thriving coral reefs, and UNESCO-listed nature reserves are among the many attractions of the archipelago’s 115 islands. The larger inner islands are quite developed for tourists, studded with many luxurious five-star resorts. The natural wonders of the Seychelles are clearly its prime asset.

Given this, the Seychelles have now established 154,000 square miles of marine protected areas, fulfilling a pledge to protect nearly a third of its vast territorial waters. This is an area twice the size of Great Britain.

About half of the newly protected areas will be “no-take zones” in which economic activity such as fishing and mining will be prohibited. Only limited economic activities will be permitted in the other half of the protected areas.

The President of the Seychelles signed the decree establishing the marine reserve in mid-March. The reserve will help protect the nation’s fisheries resources and safeguard a host of species including endangered sea turtles, sharks, and the Indian Ocean’s last remaining population of dugongs, which are marine mammals similar to manatees.

The funding for managing and protecting the new marine reserves will come from what is termed a debt-for-nature deal. It is an agreement that was worked out with the help of The Nature Conservancy that allows the country to restructure nearly $22 million in foreign debt in exchange for protecting marine resources and enacting climate adaptation measures.

This major expansion of the Seychelles’ marine protected area is a major step in the conservation of the archipelago’s biodiversity. The success of that conservation will ultimately depend upon enforcement, public-private partnerships, and innovative management.

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Seychelles Creates a Marine Reserve Twice the Size of Great Britain

Photo, posted October 22, 2017, courtesy of Falco Ermet via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Refugee Corals

August 30, 2019 By EarthWise Leave a Comment

As climate change warms the ocean, subtropical environments are becoming more favorable for corals than the equatorial waters where they traditionally thrived. As a result, drifting coral larvae are settling and growing in new regions.

According to new research in the journal Marine Ecology Progress Series, the number of young corals on tropical reefs has declined by 85% over the past 40 years. At the same time, the numbers on subtropical reefs has doubled.

Only certain types of coral can reach these new subtropical locations. That depends on how far the microscopic larvae can swim and drift on currents before they exhaust their limited fat stores. Thus, the reef ecosystems that develop have new blends of species that have previously never coexisted. It is not clear how long it will take for the new systems to reach equilibrium.

Coral reefs are complicated systems that depend on the interplay between species to enable their healthy functioning. Apart from the corals themselves, there are the coraline algae that symbiotically coexist with them. How all of this will play out in these evolving ecosystems is unknown.

In the meantime, the research has found that these refugee corals are settling at latitudes up to 35 degrees both north and south of the equator. It is no longer so clear what constitute native species in the reefs. It remains to be seen whether new reefs in subtropical oceans can support the incredible biodiversity seen in tropical reefs. But ultimately, these changing ecosystems could potentially bring new resources and opportunities, such as fishing and tourism, to places where they never existed before.

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Coral Reefs Shifting Away from Equatorial Waters

Photo, posted March 22, 2011, courtesy of Simone Lovati via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Keeping Lights On For Turtles

August 8, 2019 By EarthWise Leave a Comment

Gillnets are one of the most common types of fishing gear and are used extensively in most places where people fish for food. They operate by suspending a wall of netting in the water column.

Unfortunately, they are not selective in the species they catch. Sea turtles are one of the most common bycatch species that become entangled in these nets. When turtles are caught in gillnets, they can drown and die. Marine mammals, seabirds, and sharks are also frequently caught in gillnets.

Recently, researchers have been experimenting with illuminating the nets with LED lights to see if increasing net visibility reduces sea turtle bycatch.

Studies in Mexico show green sea turtle bycatch is reduced between 40-60% with no changes in target catch. Studies in Peru show green sea turtle bycatch is reduced between 65-80% with no changes in target catch. Studies in Indonesia show green olive ridley, and hawksbill sea turtle bycatch is reduced by 60% with increases in target catch and catch value.

Recent research shows that net illumination also reduces bycatch of other protected species such as seabirds, sharks and rays, as well as dolphins and porpoises.

The use of illuminated gillnets could prove beneficial to both sea turtles and fisherman by reducing the bycatch that can damage fishing gear.

Studies are now underway off the coast of North Carolina, where state gillnet fisheries are carefully managed to reduce turtle bycatch. Initial studies show that net illumination does not change target catch rates and may even decrease the bycatch of unwanted fish species. When it comes to protecting sea turtles, it looks like a good idea to keep the lights on.

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Illuminated Nets Could Provide A Brighter Future For Sea Turtles

Photo, posted June 2, 2016, courtesy of NOAA via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Climate Change And Global Fisheries

April 12, 2019 By EarthWise Leave a Comment

A Rutgers University-led study published in the journal Science has shown that climate change has taken a toll on many of the world’s fisheries and that over fishing has magnified the problem.

Seafood has become an increasingly important source of nourishment as the global population grows, especially in coastal, developing countries where it provides as much as half of the animal protein eaten. More than 50 million people worldwide work in the fisheries industry or subsist on fisheries.

Scientists at Rutgers and the National Oceanic and Atmospheric Administration studied the impact of ocean warming on 235 populations of 124 species in 38 ecological regions around the world. Species included fish, crustaceans such as shrimp, and mollusks such as scallops. They combined data on fisheries with ocean temperature maps to estimate temperature-driven changes in the sustainable catch over 8 decades. The data covered about one-third of the global catch.

According to the study, ocean warming has led to an estimated 4.1% drop in sustainable catches, on average around the world, for many species of fish and shellfish from 1930 to 2010. In five regions that include the East China Sea and the North Sea, the estimated decline was 15 to 35%.

The researchers recommend that fisheries managers eliminate over fishing, rebuild fisheries, and account for climate change in fisheries management decisions. Over fishing provides a one-two punch to fisheries facing warming waters. It not only makes fisheries more vulnerable to ocean warming but continued warming will also hinder efforts to rebuild over fished populations.

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