TITLE: Tuna Species Face Uncertain Future Due to Climate Change and Overfishing
https://www.natureworldnews.com/articles/60188/20240108/tuna-species-face-uncertain-future-due-climate-change-overfishing.htm
EXCERPT: The Indian Ocean, known for its rich biodiversity and abundant marine life, is facing an unprecedented crisis. The yellowfin tuna, a species integral to the ecosystem and a popular choice for sashimi and poke bowls globally, is witnessing a sharp decline in population.
A recent study published in Ocean and Coastal Management reveals alarming statistics that could potentially lead to catastrophic consequences not just for the marine ecosystem but also for coastal communities dependent on fishing.
Overfishing has been identified as the primary culprit. Industrial exploitation since 1950 has led to a staggering 70% decline in biomass of yellowfin tuna populations managed by Regional Fisheries Management Organizations (RFMO) in the Indian Ocean.
This overexploitation threatens not only the balance of life underwater but also impacts millions who rely on these waters for livelihood and sustenance.
According to the study, the current fishing pressure is unsustainable and exceeds the maximum sustainable yield (MSY) by 28%.
This means that the fish are being harvested faster than they can reproduce, resulting in a depletion of the stock. The study also warns that if the current trend continues, the yellowfin tuna population could collapse by 2026.
The study's lead author, Dr. Maria Lourdes Palomares, a senior scientist at the Sea Around Us initiative at the University of British Columbia, said that the situation is dire and requires urgent action.
"The Indian Ocean yellowfin tuna are in a critical state. They are overfished and overfishing is still ongoing. We need to reduce the fishing mortality by at least 40% to prevent further declines and ensure the long-term sustainability of this resource," she said.
TITLE: Off-radar fishing threatens efforts to preserve stocks, study warns
https://www.ft.com/content/d77fff4d-a9c6-4224-89fc-b3b08d1d833b
EXCERPT: About 75 per cent of the world’s industrial fishing vessels are not publicly tracked, according to research by conservation organisation Global Fishing Watch (GFW), threatening food security, livelihoods and marine ecosystems.
While the footprint of land-based extractive industries such as agriculture is plotted almost down to the last square metre, oceans were “still the wild west”, said David Kroodsma, one of the study’s lead authors and GFW’s director of research and innovation.
This discrepancy leaves governments and organisations operating in the dark, hindering efforts to achieve a global commitment made at the 2022 COP15 biodiversity summit to protect at least 30 per cent of land and sea by 2030, he said.
GFW’s study, published in the journal Nature on Wednesday, used GPS positions from hundreds of thousands of ocean-going vessels as well as satellite radar imagery and artificial intelligence to track activity in the sea between 2017 and 2021.
It found that on average 63,000 vessels were detected at any given time. About half were industrial fishing vessels, three-quarters of which were off-radar, including many around Africa and south Asia.
Of the remainder, including container ships and fuel tankers as well as passenger and supply vessels, a quarter were untracked.
Kroodsma said some of these so-called ghost ships lacked automatic identification system (AIS) transponders, which broadcast their location and identity to coastal authorities and other vessels. Others turned off the devices, often because they were engaged in illicit activities such as unregulated or illegal fishing or forced labour, he added.
As much as 20 per cent of fishing was potentially unregulated or conducted illegally, he estimated, “but the truth is, we don’t actually know because the data is so poor”. The study also found that the global distribution of industrial fishing differs from the generally understood pattern.
According to AIS data, Europe and Asia have similar levels of activity in terms of fishing hours. But with non-broadcasting ships factored in, Asia accounted for 70 per cent of global fishing activity, compared with 12 per cent for Europe.
North America and Africa’s total tracked and untracked fishing was 7 per cent of the global total each, while in South America and Australia it was 4 and 2 per cent respectively.
Another key finding was that untracked fishing vessels routinely entered marine protected areas, with an average of five operating in the Galápagos Marine Reserve and 20 in the Great Barrier Reef each week.
To protect such areas and safeguard fish stocks, governments should mandate that all vessels are publicly trackable, according to campaign group Oceana. “If you’re fishing on the ocean, you’re fishing on a public resource and you should be required to prove that you are doing so legally,” said chief executive Andrew Sharpless.
According to UN Food and Agriculture Organization estimates, a third of the world’s fish stocks are overexploited, meaning fish are being caught faster than they can reproduce. Critical marine habitats are also being depleted, with between 30 and 50 per cent lost because of human activity.
Fishing activity decreased globally by 12 per cent during the Covid-19 pandemic and has not yet fully recovered, but previous overfishing meant many stocks were nonetheless at their limit, according to GFW. “We are already catching all the fish we can possibly catch,” Kroodsma said.
Overfishing represents a risk not only for marine ecosystems but also for the 500mn people around the world who rely on the fishing sector for their livelihoods, he warned. Fish stocks are also crucial for global food security.
TITLE: How Terrestrial Turds Lead to Marine Maladies
https://hakaimagazine.com/features/how-terrestrial-turds-lead-to-marine-maladies/
EXCERPT: More than one-quarter of the world’s marine mammal species are already listed by the International Union for Conservation of Nature as threatened with extinction. Various factors are to blame, including overfishing, maritime traffic, and pollution, and now land-borne diseases, previously overlooked, are attracting more attention—and Duignan is only one of a cohort of veterinarians, pathologists, marine biologists, and volunteers studying them.
Karen Shapiro, an associate professor of pathology, microbiology, and immunology at the University of California, Davis (UC Davis), specializes in aquatic zoonotic pathogens. She says the rise in terrestrial diseases in marine mammals illustrates what she and her colleagues refer to as the land-sea connection, in which urbanization and its attendant alteration of habitat have led to a rise in diseases affecting marine mammals.
Urban and suburban landscapes—with their vacant lots, alleyways, green belts, and various nooks and crannies—provide plentiful safe havens for opossums, feral cats, rats, mice, and dozens of other species that are the terrestrial hosts for an array of pathogens. As cities expand, so, too, do populations of these animals that thrive in human-altered landscapes and are potential reservoirs of disease. Given that 40 percent of the planet’s human population resides within 100 kilometers of a coastline, this is a global problem.
As concrete, asphalt, and other impervious surfaces cover more and more coastal land, pathogens are swept more readily into rivers, streams, and the ocean. This runoff exposes sea lions and other marine mammals, particularly those that live along urban coastlines or at the mouths of major river systems, to a host of pathogens—either directly in the water column or because they have accumulated in the organisms that marine mammals eat. A recent study by Chinese researchers, for example, showed that the prevalence of toxoplasmosis-causing T. gondii in various species of shellfish and fish was two to three times higher in areas that received urban stormwater runoff than in areas that did not.
In the aftermath of [last] year’s atmospheric river storms in California, rescuers saw a rash of sick sea otters along the outlet of the Pajaro River, near Monterey. The outbreak, Shapiro says, was likely linked to the huge volumes of runoff flowing into the ocean from the agricultural and urban landscapes of the Salinas Valley. Major storms create “flushing events” that expose sea otters, sea lions, and other marine mammals to massive amounts of pollutants and pathogens.
“California has a very distinct dry season and wet season,” Shapiro says. “For months, we have an accumulation of feces from cats, for Toxoplasma, and from opossums, which are the definitive hosts for Sarcocystosis. After the first few rains, all this waste is carried to the coast.”
Climate change has had the unfortunate effect of intensifying the flushing events caused by atmospheric rivers, boosting precipitation and, thus, the amount of runoff ending up in the sea. But that’s only part of the problem. The global ocean has absorbed 90 percent of the excess warming generated by human emissions, and in general, a warmer ocean is a sicker ocean. Higher marine temperatures can lead to massive algal blooms; some of these, like the alga Pseudo-nitzschia australis, have well-documented toxic effects on marine mammals.
Ocean warming seems to be a key driver of marine diseases in nonmammals, especially invertebrates like corals and sea stars. A marine heatwave known as the Blob coincided with a major outbreak of sea star wasting disease from 2013 to 2016, primarily on the Pacific coast, wiping out populations of over 20 sea star species; almost six billion sunflower stars alone were killed from Alaska to Mexico. As Drew Harvell, a professor of marine ecology at New York’s Cornell University, wrote in her 2019 book Ocean Outbreak, “We have created a perfect storm of outbreak conditions … Given the many ways we have mistreated our oceans and made conditions friendlier to microbes, it is no wonder that we are beginning to see more outbreaks of marine diseases.”