Often referred to as the “eyes and ears” guarding fish from overexploitation, human observers spend days to months aboard fishing fleets around the world monitoring the tuna that’s hauled from oceans and destined for our plates as sushi, steaks and in cans.

Their job is an important and, at times, dangerous one: collect scientific data vital for informing the health of marine ecosystems, and sometimes pit themselves against hostile crews if they spot illegal activity. This frontline work has cost the lives of some observers.

But for more than a year, there have been few independent observers aboard fishing vessels. As the COVID-19 pandemic spread, observers were ordered to return to their home ports. Yet, fishing fleets have continued to traverse oceans largely unhindered.

With much of the critical data used to monitor and manage fisheries now logged by captains who have an economic incentive to underreport their catch, experts fear illegal fishing has increased and could undermine already over-exploited fish populations.

“Without observers on board, opportunities for IUU [illegal, unreported or unregulated] fishing has increased and the expectation is that unscrupulous fishing vessels and operators are going to take advantage of that,” said Jamie Gibbon, the manager of International Fisheries at Pew Charitable Trusts.

Prior to the pandemic, one in five of marine caught fish were estimated to be caught illegally, damaging marine environments and contributing to over-exploitation of fish populations. What drives this is money, as vessels pay no taxes or duties on their illegal catches.

In April last year, as the COVID-19 crisis escalated globally, 19 leading NGOs expressed concern in an open letter that suspended monitoring systems that involved human contact would increase IUU fishing, and in doing so, could undermine global fish stocks.

In the same month the letter was released, an estimated 100 vessels, mostly Chinese-flagged, were caught illegally fishing in Argentinian waters. The vessels had waited until after nightfall to turn off their tracking systems in an attempt to avoid detection.

How much the absence of observers aboard ships has impacted global fishing stocks will remain unknown for several years given the time it takes to compile and verify catch data, said Glen Holmes, an officer with Pew’s International Fisheries Program.

But Mr Holmes said there will be an ongoing question mark on bycatch data, the number of animals – sometimes endangered – crucial to a healthy ecosystem such as dolphins, whales, sharks, manta rays, and turtles that are swept up in nets and often die before crews throw the species back overboard.

“Generally speaking the bycatch data that don’t have observers aboard is a hell of a lot less reliable than bycatch data where observers are on board,” Mr Holmes said.

There was also concern about the lack of observers currently watching transshipments, Mr Holmes said, where vessels that stay at sea for months offload their catches onto refrigerated transport boats, creating a loophole that enables vessels to underreport their catch or commit illegal activity without a trace.

In a newsletter released in April last year by the Pacific’s peak regional science organisation, a fisheries officer described not being physically present onboard vessels feeling like “an itch on your back you can’t reach.”

“A vessel can literally catch 1000 species of interest, not report them, trans-ship them to a carrier and it will all go unseen, very, very easily. As a boarding officer as well, it feels really weird not showing a presence by going on these vessels and just checking them. Yet, they are fishing in our waters and trans-shipping in our lagoon,” the officer said.

The pandemic has exacerbated problems that already existed. Recent research shows the number of observers aboard vessels prior to the pandemic does not provide accurate data on the health of fisheries.

But the past 12 months have delivered a silver lining. COVID-19 has supercharged regional fisheries organisations in the Pacific, Atlantic, and Indian Ocean to transition to long talked about e-monitoring and e-reporting systems.

“It’s really important that there is still a level of human observer coverage. But we see electronic monitoring as the way to get that really low monitoring coverage all the way up to 100 per cent,” Mr Gibbon said.

How this could improve fisheries science, particularly for bycatch species, is best displayed by Australia’s domestic fisheries where these systems are already in place. Over the past 10 years, there has been an exponential increase in bycatch data, Mr Holmes said.

“Now that there’s cameras onboard every vessel, and random analysis of that camera data, no boat captain knows whether or not his or her camera data is being analysed, so the logbook reporting has improved enormously.”

The move to robust e-monitoring is also good news for observer’s safety. Though observers board vessels for science purposes, they can take on ad-hoc compliance roles when illegal fishing, or drug or human trafficking is spotted. This is thought to be the cause of observers being harmed, with 1-2 observers having died or disappeared mysteriously every year over the past six years.

With consensus needed among the nations part of the regional fisheries management organisations before systems are rolled out, how long it will take to globally reach this standard is unknown. But Mr Gibbon said the step forward was “encouraging”.