https://theconversation.com/hu...t-must-change-243831


Humans are killing off the old and wise animals that hold nature together. Here’s what must change

Published: November 21, 2024 2:07pm EST
Author
Keller Kopf
Senior Lecturer in Ecology, Charles Darwin University

Disclosure statement
Keller Kopf does research on long-lived animals and has received grants associated with the management and conservation of fisheries and wildlife.

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Charles Darwin University provides funding as a member of The Conversation AU.


In humans and other animals, ageing is generally associated with a decline in biological function. But scientists are now discovering older animals perform vital roles in populations and ecosystems.

Unfortunately, however, old animals can suffer the most from human activity such as over-fishing and trophy hunting. And the value of old, wise animals is not usually considered when we manage animal populations and seek to protect biodiversity.

Our new review, published today in Science, draws on evidence from around the world to argue for a new approach called “longevity conservation”.

The loss of old and wise animals has devastating global consequences. Clearly, more must be done to prioritise their survival.


Benefits of a long life

Cold-blooded (ectothermic) animals such as fish and reptiles tend to keep growing throughout their life. This means older individuals are generally larger than younger individuals.

Being bigger has benefits, especially when it comes to feeding and reproduction. It’s widely known the number of offspring increases with age in fish and many other ectotherms. But it’s only recently been discovered that older mothers of some fish and sea turtles produce exponentially more offspring as time goes on. Their young may also have better chances of survival.

Survival rates are can be higher in offspring from older mothers in other species too. For example, in birds older parents and their helpers often provide more food and better habitat for their chicks, improving fledgling survival rates.

Females from a range of species tend to select older males as mates. These males commonly assume crucial social roles, such as leading long distance movements like migration, and regulating social structures, such as reducing aggressive behaviour. These behaviours influence decision-making with direct consequences for group and offspring survival.


With age comes wisdom

Some animals draw on experience accumulated over the course of their lifetime in order to make better decisions. In elephants, mothers and grandmothers are repositories of knowledge.

This “grandmother effect”, first studied in humans, also occurs in whales. Wise grandmother killer whales, which no longer reproduce, help their families find food when it is scarce and this benefits survival.

In a wide range of species, new research is showing how older individuals transmit their knowledge to others via a process called cultural transmission. The benefits of old age extend to animals such as migratory birds, pack-hunting carnivores, and even fish. For example, taking all the big fish from some populations has diminished their collective group memory often needed for migration and knowledge of spawning areas.


Examining the loss of older animals

Our research set out to build understanding of the ecology and conservation of old animals.

We assembled an interdisciplinary team of experts who work on different animals and diverse ecosystems. Our team included behavioural and wildlife ecologists as well as freshwater, marine and fisheries scientists.

We searched the literature and wrote a review. In addition, we used a machine learning topic model to delve into more than 9,000 peer-reviewed papers.

Most research has focused on the negative aspects of ageing, particularly in humans, and short-lived animal models such as fruit flies. Yet emerging evidence is showing how old wild animals contribute to populations and ecosystems.

Many of these functions benefit people too, but are being lost as old individuals are removed from the wild.

Fishing has caused a systematic decline in the abundance of old fish, with these aged individuals reduced in 79-97% of the ocean populations examined.

Old African elephants and other trophy animals are commonly poached or hunted, both legally and illegally.

But the loss of old individuals is not limited to large enigmatic species. Deep-sea coral and Antarctic sponges – which can live for thousands of years – are being harvested, damaged by fishing gear, and affected by climate change. These species cannot be replaced within our lifetime.

Species that live to advanced ages are often large, slow-growing, and slow to mature. These traits can make these species more vulnerable to extinction if older adults are killed by humans.

But when humans spare old individuals, these long-lived species are more resistant to environmental change and provide more stable ecosystem services, such as fisheries which supply protein to feed the world.

Retaining old animals tends to protect populations from poor environmental conditions such as drought and other extreme climate events, allowing species to persist against the odds. This buffering capacity is increasingly important in the face of global climate change.


Introducing ‘longevity conservation’

Old animals play vital roles in the maintenance of biodiversity and ecosystem services.

Yet harvest management and conservation practices tend not to focus on preserving age structures within populations. And the loss of old individuals is not yet recognised by the International Union for Conservation of Nature as a means of listing threatened species, or as a type of over-fishing.

To protect old individuals and maintain or restore the age structure of wild populations, we propose “longevity conservation” measures.

Decisive new policy and actions are needed to protect and restore the crucial ecological roles and services old, wise, and large animals provide. For example, formally recognising and avoiding “longevity overfishing” should be incorporated into fisheries management to help ensure the long-term sustainability of fisheries.

Biodiversity conservation and threatened species policies should protect age structure. This is particularly important in long-lived species that produce more offspring with age, or where migration, social networks and cultural transmission of knowledge are required for survival.

I have to agree to a point…old females are leaders thus should be spared

An interesting point of view with some validity but it all depends on each species way of life. Few species have males as the main repository of wisdom. Half of all people would include Homo sapiens in this group.
In African hunting few of us are targeting old females with the exception of tuskless and occasionally lionesses.
It is a fair argument to say that old bull elephants should be spared on the grounds that they keep the young bulls in line but it is not a strong enough argument to stop many bullets.
In the case of tuskless cows, should we be sparing tuskless matriarchs?
In places with adequate rainfall and year round feed like Addo Elephant Park being tuskless is an advantage as she is not going to get poached. In dry country where tusks are needed to dig for water and strip bark from trees, tuskless cows and particularly tuskless bulls, can only survive by pushing tusked animals off the water or bark, so it becomes a semi lethal gene if there are too many tuskless in a group.
Where there are too many elephants I personally believe that tuskless should be shot on sight with no limit on quota and if she happens to be the matriarch, tough! Where elephants are scarce no one is hunting tuskless anyway.
In the case of lions, where there are to many of them, obviously shooting males over 5 years of age is the quickest way to reduce the population because his young replacement lion is going to kill off a whole generation of cubs. Shooting old lionesses will also help reduce the population by decreasing the prides hunting success rate.
Unfortunately there are few areas where there are too many lions and it could be argued that the best way to increase the population is to shoot the young nomadic males, particularly those in coalitions and leave the old males to breed.
Not an idea likely to be popular!
The argument that old male lions are being shot after they have been replaced by younger ones is largely a fallacy. Of course it does occur but they have usually been so injured the Hyaenas soon clean them up.
Does anyone have the statistics on the average age of lions shot in Zimbabwe or Tanzania? My guess would be 6 or 7 but I am often wrong and very open to correction.

Total hogwash end around by the anti’s to stop what they don’t like or agree with. Bottom line to saving wildlife, particularly African wildlife, is stop poaching while providing abundant habitat resources with skillful and accurate management programs. The hunting model is immensely efficient at all three.

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Originally posted by tomahawker:
Total hogwash end around by the anti’s to stop what they don’t like or agree with. Bottom line to saving wildlife, particularly African wildlife, is stop poaching while providing abundant habitat resources with skillful and accurate management programs. The hunting model is immensely efficient at all three.

Precisely! Land protection and preservation is the key to maintaining Africa's wildlife. Well managed, sustainable hunting practices with incorporation of active anti-poaching practices pays huge dividends for the wildlife.

Something I have contemplated is how many trips to a distant water hole or feeding ground are needed before an animal in a herd remembers where it is? Probably no good answer as how would we know, but, since wildlife needs knowledge of such to survive I would think they learn fast or die.

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Charles Darwin University

Thats as far as I got and all I needed to see.