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Eat the Problem? Why we can’t eat our way out of our invasive species problem  

Invasive species are a major driver of extinction around the world (IBPES 2023). Controlling these species has proven difficult and expensive. A strategy that has been continually proposed is to commercialise the control of overabundant invasives, i.e. eat our way out of the invasive species problem (Pasko & Goldberg 2014).

On the surface, it is an appealing argument: encouraging greater harvest of the target species, utilising what would otherwise be a ‘wasted resource’, and generating economic revenue from the control efforts. Additionally, consuming invasive species offers a more sustainable and ethical option than current industrial farming practices. Some of Australia’s most problematic invasive species are considered to be good food sources, such as rabbits and deer.

However, despite the many attempts around the world, there are no compelling examples of a commercial market successfully controlling, let alone eradicating an invasive species. More often, the set-up of markets has proven counterproductive (see Nunez, et al., 2012; Pasko & Goldberg 2014).

At best, these strategies have made a minimal and ephemeral impact on the population due to the limited impact harvests generally have on the population size. At worst, the establishment of commercial markets to bolster invasive species management exacerbates the issue, causing more harm than good (reviewed in Nunez, et al., 2012).

The first issue with the ‘eat the problem’ idea is one of population dynamics. While it seems logical that each animal harvested contributes to reducing a population, shrinking a population over time is more complex than that. The only way to reduce a population over time is to remove more animals each year than are being born. For animals with high reproductive rates, such as rabbits, this can mean more than 80% of the population must be killed each year. Any harvest rates below this rate will not reduce the population size, but only slow how quickly the population is growing. Commercial harvests are rarely able to achieve sufficient removal rates over the timeframes required to eradicate invasive species from a region (e.g. Cresswell et al. 2023, Pople & Froese, 2012, Ramulaetal et al., 2008, Zeng & Gerritsen 2012). Even the most successful commercial markets set up to control invasives, such as those created for lionfish removal in the USA and feral deer control in New Zealand have failed to make a substantial impact on the population as a stand-alone strategy (Barbour et al.2011; Malpica-Cruz et al., 2021; Nugent and Choquenot, 2004).

The second issue is one of economics and markets. The objective for most, if not all, invasive species management programs is to reduce the population to the point where it can be eradicated or the negative impacts are acceptably low. The objective of a commercial market, once established, is to self-perpetuate and keep generating revenue; these objectives are at odds with one another (Malpica-Cruz et al., 2021). Invasive species management wants to remove animals from the landscape but a market creates an incentive to keep that species in the landscape. In some cases, this financial incentive has led to the deliberate introduction of invasive species for greater profits (e.g Elmendorfetal.2005). For example, a major driver of the spread of feral pigs in southern USA has been the pig bounty as pigs were introduced into new areas as a source of profit (McCann et al., 2018). A similar situation has been observed with feral pigs in WA (Spencer and Hampton 2005).

Are there any positives to the ‘eat the problem’ strategy? Eat the problem type campaigns have served as an educational outreach tool, highlighting the need to control invasives. Several “Eat the problem” campaigns have assisted in bringing greater attention to the threats posed by invasive species.

However, these campaigns risk trivialising the issue, leading the public to believe that a quick fix exists for invasive species issues. For example, statements like ‘Ordering lionfish when it’s presented on menus or going lionfish fishing on holiday are ways to help combat this major issue in these oceans,’ make it seem like a serious invasive pest can be managed simply by consumers eating a different type of meat. Effective invasive species management requires coordinated, resourced efforts at the landscape scale with very targeted goals around population reduction or eradication.

Overall, the commercialisation of invasive species control has yet to be proven as effective of a strategy as promised. In some instances, it has worsened the situation. However, strategies for the use of at least some culled individuals can be important for gaining public support for control activities of some species.

References

Benxiang Zeng & Rolf Gerritsen (2013) Inadequate contribution of commercial harvest to the management of feral camels in Australia, Journal of Environmental Planning and Management, 56:8, 1212-1224,

Cresswell, K., Hartmann, K., Gardner, C., & Keane, J. 2023. Tasmanian Longspined Sea Urchin Fishery Assessment 2021/2022. Institute of Marine Science, University of Tasmania.

McCann, B. E., Smyser, T. J., Schmit, B. S., Newman, R. A., Piaggio, A. J., Malek, M. J., … & Simmons, R. B. (2018). Molecular population structure for feral swine in the United States. The Journal of Wildlife Management, 82(4), 821-832.

Nunez, MA, et al., (2012) Invasive species: to eat or not to eat, that is the question. Conservation Letters 5: 334–341.

Nugent, G., & Choquenot, D. (2004). Comparing cost‐effectiveness of commercial harvesting, state‐funded culling, and recreational deer hunting in New Zealand. Wildlife Society Bulletin, 32(2), 481-492.

Parkes, J. P., Nugent, G., & Warburton, B. (1996). Commercial exploitation as a pest control tool for introduced mammals in New Zealand. Wildlife biology, 2(3), 171-177.

Pople, A. R., & Froese, J. G. (2012). Distribution, abundance and harvesting of feral goats in the Australian rangelands 1984-2011. Final report to the ACRIS Management Committtee.

Spencer, P. B., & Hampton, J. O. (2005). Illegal translocation and genetic structure of feral pigs in Western Australia. The Journal of Wildlife Management, 69(1), 377-384.

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Save the Snowies

The NSW government is one step away from allowing aerial control of feral horses in Kosciuszko National Park. This is huge news and a crucial step for our threatened native wildlife and the fragile alpine ecosystems they call home.

Dear Project Team,

[YOUR PERSONALISED MESSAGE WILL APPEAR HERE.] 

I support the amendment to the Kosciuszko National Park Wild Horse Heritage Management Plan to allow our incredible National Parks staff to use aerial shooting as one method to rapidly reduce feral horse numbers. I want to see feral horse numbers urgently reduced in order to save the national park and our native wildlife that live there.

The current approach is not solving the problem. Feral horse numbers have rapidly increased in Kosciuszko National Park to around 18,000, a 30% jump in just the past 2 years. With the population so high, thousands of feral horses need to be removed annually to reduce numbers and stop our National Park becoming a horse paddock. Aerial shooting, undertaken humanely and safely by professionals using standard protocols, is the only way this can happen.

The government’s own management plan for feral horses states that ‘if undertaken in accordance with best practice, aerial shooting can have the lowest negative animal welfare impacts of all lethal control methods’.

This humane and effective practice is already used across Australia to manage hundreds of thousands of feral animals like horses, deer, pigs, and goats.

Trapping and rehoming of feral horses has been used in Kosciuszko National Park for well over a decade but has consistently failed to reduce the population, has delayed meaningful action and is expensive. There are too many feral horses in the Alps and not enough demand for rehoming for it to be relied upon for the reduction of the population.

Fertility control as a management tool is only effective for a small, geographically isolated, and accessible population of feral horses where the management outcome sought is to maintain the population at its current size. It is not a viable option to reduce the large and growing feral horse population in the vast and rugged terrain of Kosciuszko National Park.

Feral horses are trashing and trampling our sensitive alpine ecosystems and streams, causing the decline and extinction of native animals. The federal government’s Threatened Species Scientific Committee has stated that feral horses ‘may be the crucial factor that causes final extinction’ for 12 alpine species.

I recognise the sad reality that urgent and humane measures are necessary to urgently remove the horses or they will destroy the Snowies and the native wildlife that call the mountains home. I support a healthy national park where native species like the Corroboree Frog and Mountain Pygmy Possum can thrive.

Kind regards,
[Your name]
[Your email address]
[Your postcode]


Dear Project Team,

[YOUR PERSONALISED MESSAGE WILL APPEAR HERE.] 

I support the amendment to the Kosciuszko National Park Wild Horse Heritage Management Plan to allow our incredible National Parks staff to use aerial shooting as one method to rapidly reduce feral horse numbers. I want to see feral horse numbers urgently reduced in order to save the national park and our native wildlife that live there.

The current approach is not solving the problem. Feral horse numbers have rapidly increased in Kosciuszko National Park to around 18,000, a 30% jump in just the past 2 years. With the population so high, thousands of feral horses need to be removed annually to reduce numbers and stop our National Park becoming a horse paddock. Aerial shooting, undertaken humanely and safely by professionals using standard protocols, is the only way this can happen.

The government’s own management plan for feral horses states that ‘if undertaken in accordance with best practice, aerial shooting can have the lowest negative animal welfare impacts of all lethal control methods’.

This humane and effective practice is already used across Australia to manage hundreds of thousands of feral animals like horses, deer, pigs, and goats.

Trapping and rehoming of feral horses has been used in Kosciuszko National Park for well over a decade but has consistently failed to reduce the population, has delayed meaningful action and is expensive. There are too many feral horses in the Alps and not enough demand for rehoming for it to be relied upon for the reduction of the population.

Fertility control as a management tool is only effective for a small, geographically isolated, and accessible population of feral horses where the management outcome sought is to maintain the population at its current size. It is not a viable option to reduce the large and growing feral horse population in the vast and rugged terrain of Kosciuszko National Park.

Feral horses are trashing and trampling our sensitive alpine ecosystems and streams, causing the decline and extinction of native animals. The federal government’s Threatened Species Scientific Committee has stated that feral horses ‘may be the crucial factor that causes final extinction’ for 12 alpine species.

I recognise the sad reality that urgent and humane measures are necessary to urgently remove the horses or they will destroy the Snowies and the native wildlife that call the mountains home. I support a healthy national park where native species like the Corroboree Frog and Mountain Pygmy Possum can thrive.

Kind regards,
[Your name]
[Your email address]
[Your postcode]