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Eight billion people, SARS-CoV-2 ancestor and illegal fishing

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Fishing vessels have legitimate reasons to turn off their position-tracking systems — but there are some suspicious reasons, too.Credit: Anthony Wallace/AFP/Getty

Suspected illegal fishing revealed by tracking data

When fishing vessels hide their locations, they sometimes reveal a wealth of information. Gaps in tracking data can suggest illegal activity, finds a modelling study (H. Welch et al. Sci. Adv. 8, eabq2109; 2022).

Some ships carry automatic identification systems (AIS), which pinpoint their locations and help to prevent collisions, but can be turned off. Heather Welch, a spatial ecologist at the University of California, Santa Cruz, and her colleagues analysed more than 3.7 billion signals from vessels, sent between 2017 and 2019. They identified gaps in the data to find hotspots where fishing vessels frequently disabled their devices on purpose. Vessels hid up to 6% of their activity — more than 4.9 million hours over 3 years. Some of these gaps were probably legitimate but others could mask illegal fishing, according to the study. Illegal, unreported and unregulated fishing costs the global economy up to US$25 billion each year. It is also detrimental to marine life.

The team found that 82% of time lost to AIS disabling happened on ships flagged from Spain, the United States, Taiwan and the Chinese mainland. However, most vessels that use AIS come from middle- and upper-income countries.

A large-eared horseshoe bat (Rhinolophus robertsi) flying out of a cave in Cooktown, Queensland, Australia.

Evidence suggests that SARS-CoV-2 probably emerged in horseshoe bats.Credit: Bruce Thomson/Nature Picture Library

Chances of finding COVID ancestor ‘almost nil’

The virus that causes COVID-19 probably shared an ancestor with bat coronaviruses more recently than scientists had thought. But finding the direct ancestor of SARS-CoV-2 is very unlikely, say researchers.

The full genomes of SARS‑CoV-2 and several closely related bat coronaviruses suggest that they shared a common ancestor several decades ago. But the viruses are known to swap chunks of RNA, a process called recombination, so each section has its own evolutionary history.

In an analysis presented at the 7th World One Health Congress in Singapore on 8 November, scientists compared fragments of coronavirus genomes. The results suggest that some sections of bat coronaviruses and SARS-CoV-2 shared a common ancestor as recently as 2016 — just three years before the virus emerged in people in late 2019. The work has not been peer reviewed.

The finding narrows the time between the ancestor of SARS‑CoV-2 originating in bats and the virus jumping to people. But it also highlights how difficult it will be to find the direct ancestor of SARS‑CoV-2 in bats, given how often coronaviruses recombine. The chances of finding a direct ancestor “are almost nil”, says Edward Holmes, an evolutionary virologist at the University of Sydney in Australia.

World population passes eight-billion mark

According to models from the United Nations (UN), the world’s population reached 8 billion on 15 November — a mere 12 years since it passed 7 billion, and less than a century after the planet supported just 2 billion people (see ‘People of the world’).

The latest UN population update, released in July this year, also revises its long-term projection down from 11 billion people to 10.4 billion by 2100.

Although approximate, this could be the most reliable estimate that the UN has produced so far. The organization has changed how it analyses data, switching from five-yearly to annual intervals. And there has been a steady improvement in recent decades in the ability and capacity of many countries to collect statistics.

The most significant factor behind the UN’s updated forecast is that data from China have been more reliable since the end of the country’s one-child policy in 2015. The UN predictions suggest that China’s population has already peaked, and will now shrink year-on-year until at least the end of the century.

Significant blind spots remain, however, particularly for countries that are experiencing humanitarian crises and conflicts, such as Somalia, Yemen and Syria.

People of the world: Line chart showing global population since 1950, which is expected to reach 10.4 billion by 2100.

Source: UN Population Division

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