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This year’s whale season offered spectacular encounters with these majestic giants as thousands of whales migrated along Australia’s east coast.

But behind the scenes, Australian scientists have noticed a troubling rise in the number of whales caught and tangled in ropes, nets and fishing lines. We documented 48 separate entanglements of humpback whales in the past few months on the east coast. This follows last year’s estimate of 45 entangled whales.

We collected this information from social media posts, newspaper articles and enquiries to authorities. Unfortunately, there is no official database, although we need one. The International Whaling Commission has voluntary reports on its portal.

Consistent with the increasing population size, entanglements of humpback whales in set fishing gear have been rising steadily since the 1990s. In 2017, for example, there were about 20.

Rising entanglements are part of a concerning trend seen in the United States and elsewhere. The US National Oceanic and Atmospheric Administration confirmed 95 large whale entanglements in 2024, up 48% on the previous year.

Why do whales get tangled?

Humpback whales (Megaptera novaeangliae) accounted for most of the large whale entanglements we recorded. Fishing gear such as nets and crab pots accounted for around 70% of these reported entanglements. The remainder are due to shark net programs, where gill nets and drumlines are placed along popular beaches to deter or catch sharks.

The biggest threats are posed by fishing gear with long lines or excessive rope in areas where whales feed and migrate. Whales more often get entangled in areas where fishing gear frequently changes locations. The highest numbers of entanglements were during the peak northern migration in June and peak southern migration in September.

Humpback populations are growing. But entanglements are not only due to increasing numbers of whales. Food shortages linked to faster Antarctic sea ice melt are forcing whales to feed in places where more fishing occurs.

What happens to entangled whales?

This whale season, we’ve been able to follow several individual entangled whales through reports from members of the public. In some cases, the same whale was seen over several weeks and thousands of kilometres apart.

One humpback was first spotted in Hervey Bay on July 28 with thick rope around its body. On August 2, it was seen off the Gold Coast. By September 16, it was near Kiama in New South Wales. By then, the rope had finally come off. The whale’s health had severely declined. It had lost weight and was covered in sea lice – a sign of poor condition.

It’s most dangerous for a whale to be tangled in fishing gear with floats and long ropes, as these dramatically reduce its ability to swim and dive. To survive, it’s forced to use vital energy reserves. Shorter lines without floats can still be deadly, cutting deep into tail flukes or pectoral fins and causing painful wounds and infections. As their bodies weaken, whales often lose more than half their body weight, develop infections and become covered in sea lice.

Recovery after being entangled is possible if a whale remains strong enough to complete the migration and reach its feeding grounds. But the outlook is grim for many. Researchers found North Atlantic right whales entangled for several weeks often don’t survive.

How are whales freed?

This season, Australian rescue teams freed 18 whales. Most of these involved whales caught in gill nets and drumlines used in Queensland’s shark control program. Each release represents a remarkable effort from rescue teams.

Unfortunately, removal is no guarantee of survival. The damage may already be done. Survivors can suffer long-term consequences. Female whales that survive severe entanglement often fail to reproduce the following season.

On average, only a third of entangled whales are seen again after the initial report. Less than a quarter are disentangled.

Rescuing entangled whales is a delicate operation requiring expertise, specialised equipment and good weather.

Specialised teams such as the Sea World Foundation Rescue Team on Australia’s east coast and the NSW Parks and Wildlife Service Large Whale Disentanglement Teams are trained for these complex missions.

To free the whales, experts use specialised tools such as hooked knives on long poles, “flying” knives (attached to a rope and buoy), grappling hooks and large floats that can be attached to the tangled gear to slow the whale for a safer approach. Choosing the right ropes to cut, the right cutting location and the right order is crucial.

The success of a rescue depends on many factors, from sea condition to the whale’s behaviour, to the skill and coordination of the disentanglement team.

In many countries, members of the public are not permitted to attempt to free tangled whales. But as numbers of entanglements have grown, concerned Australians have mounted several dangerous rescue attempts, including people jumping onto whales to try and cut the lines. These ad hoc rescue missions can make the situation worse for the whale. If the wrong lines are cut, it can accidentally tighten others. These attempts can be life-threatening for rescuers.

What can we do better?

We need to get better at predicting the movements of entangled whales. By analysing migration patterns and ocean conditions, researchers could develop forecast tools to predict where an entangled whale might travel next, helping rescue teams intercept it more effectively. In some cases, attaching satellite trackers to the trailing gear has provided vital real-time data on a whale’s location and movement.

Better coordination between response groups is also essential. A centralised reporting system and data sharing across states and jurisdictions would help track incidents and whales, streamline rescue responses and strengthen research efforts.

The most important step is to prevent entanglements in the first place. To that end, we need to support the fishing industry to adopt safer practices, such as improving gear management and accountability.

Innovations such as ropeless fishing gear could cut the numbers of entangled whales. At present, they are expensive. Government incentives and shared investment could make these technologies more accessible.

If nothing is done, more whales will be entangled, and we will see more emaciated carcasses wash ashore.

Olaf Meynecke, Research Fellow in Marine Science and Manager Whales & Climate Program, Griffith University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Western Australia’s Cottesloe Beach has been closed due to concerns a swimmer there was taken by a great white shark.

The public is understandably worried, but the local mayor says no shark nets will be installed. Is this the right decision? Do shark nets work?

How did all this netting get started?

Along 51 beaches and 250 kilometers of New South Wales coastline, beach nets line the surf.

Beach nets were approved in 1935, but only as a two-year experiment. However, by 1937 there had been no shark bites and no Government funding.

The reason the state financed netting that year was NSW’s imminent 150th Anniversary: state politicians were worried there would be a shark attack during the celebration.

During the Second World War, beach nets were removed from ocean beaches so fisheries ships could be used by the Americans. For three years, between 1943 and 1946, there were no fatal shark bites at these un-netted beaches.

At the end of the war, New South Wales Premier William McKell announced in the Sydney Morning Herald that beach nets were “quite valueless”, noting that “since meshing ceased in January 1943, there had been no shark fatality on our beaches.”

However, instead of abandoning shark nets, the Premier announced plans to use them in combination with experimental shark repellents because: “if meshing alone were used, I fear it would prove to be of little value. Worse, it would possibly lull the public into a sense of false security, leading to diminished watchfulness and possibly to tragedy.”

With no shark bites and little threat in these locations, the nets were put back and expanded to the Illawarra and Hunter under this new plan of action.

Most recently, beach nets were re-endorsed in a Department of Primary Industries Report in 2009.

What really stops shark fatalities?

The DPI’s 2009 review provided a contemporary view of shark nets. Then Environment Minister Ian Macdonald called the nets “highly successful.” Yet the report of shark bite incidents from 1937-2008 showed that of the 38 shark attacks recorded in the state, 24 of them (63%) took place at netted beaches, with 14 injuries.

The Minister and Department correctly point out that there has been only one fatality at a netted beach (1951) under this program.

But attributing low fatality rates to beach nets is questionable. Internationally, fatality rates from shark bites have declined dramatically for all shark control methods, including doing nothing.

Irish trauma researcher David Caldicott published a study in 2001 showing the survival rate for shark bites is 80%, due to better on-scene treatment and antibiotics. The leading reason for fatalities was blood loss.

(In fact, when Marcia Hathaway’s tragedy took place in Sydney Harbour in 1963 the ambulance broke down.)

The Government’s shark bite data suggest a number of possibilities. It could be that the nets are vitally needed since there were clearly sharks in those regions. But the 63% failure rate raises fundamental questions about their effectiveness.

To be fair, beach nets aren’t just installed to prevent sharks and people interacting. Nets were originally used, in 1935, to cull populations so there would be fewer sharks and therefore fewer shark alarms. In the 2009 DPI report, it was argued that, although culling is indiscriminate, the goal is to kill larger sharks to reduce the risk of a fatal shark bite incident. And killing sharks (and other marine species) is one thing nets do very well.

Is there an alternative?

At this point, I think it is important to recap the central elements.

First, shark nets were nearly left out of the report in 1935 and were only funded in 1937 as a precaution ahead of the state’s anniversary.

Second, there were no fatal shark bite incidents when the nets were removed for three years.

And third, nets have been deemed very successful even though 63% of shark attacks at ocean beaches in New South Wales have occurred at netted beaches.

In all, I suggest that at key points in the history of shark nets this has proven itself to be a story about people and politics rather than shark behaviour.

So what do we do instead? It is not a simple matter.

Beach nets are unique political dynamite. Indeed, the twitter post writes itself: “16 yr -old killed by shark at previously netted beach #bloodonourhands”.

Internationally, shark nets have been labeled a “key threatening process” for killing endangered species.

In 2011, killing endangered species to boost public confidence or to show government action is not workable. It is a disservice to the public. To restore an objective critique of this emotive issue we need a workable alternative.

Time for Australia to catch up

If killing sharks is taken off the table, then other innovative beach safety options are possible. In Cape Town, Florida, New Zealand and Hawaii, lethal shark control methods have been replaced by more modern beach safety tactics.

These tactics include greater uses of signs and flags to educate the public about marine hazards and using tracking devices on sharks to determine seasonal movements. This has begun in Sydney Harbour, but could be expanded. A fundamental question is whether shark safety should be based on decisions that governments make, with policies determining our personal level of risk in the water, or whether the public should be empowered and educated to make its own determinations?

This analysis is not intended to minimize the terrible consequences from shark bite incidents. Sharks do bite people and public safety measures should be taken.

It is not clear; however, if the status quo is actually working.

The truth about shark nets is also about “truth in government”. Government action and the public’s role cannot be obscured by the dreaded nature of these events.

The time has come for a new public dialogue about public education and beach safety regarding sharks, not simply because beach nets harm the environment, or because there are questions about whether they work, but because these 70-year-old tactics mean Australia is being left behind.

Chris Pepin-Neff, PhD Scholar, University of Sydney

This article is republished from The Conversation under a Creative Commons license. Read the original article.