The Management of Invasive Species in Marine & Coastal Environments Module 5 Incursion Management

1. The Management of Invasive Species in Marine & Coastal Environments Module 5 Incursion Management

2. Module 5 Objectives • Describe the strategies available for managing marine and coastal invasive species, once they have become established • Highlight the differences between the various incursion management strategies • Introduce the techniques used in incursion management • Describe the decision-making process for selecting the appropriate strategy

3. Strategies • Eradication • Control • Impact mitigation • Do nothing

4. Order of preference Management option Goals 1 Eradication To ensure that no individuals of the targeted IAS population exist at the end of the programme. 2 Control Although individuals will still be present, they will be at lower densities and/or in fewer, contained areas than before control was initiated. 3 Impact mitigation To reduce the severity of impacts an invasive species is causing, rather than managing the population itself. 4 Do nothing This is a worst-case scenario, although there are many examples. Doing nothing is the only option when an invasion is so out of control that any attempts to do anything would be prohibitively expensive and futile. The expenditure is not considered worthwhile, and money and resources would be better allocated to dealing with more tractable IAS.

5. Containment Don’t wait until it is too late – immediate action can save large amounts of time and money.

6. Darwin Marina / Black striped mussel

7. Use all sources of information about the IAS (national, regional and international) to help decide how best to manage it Developing the Strategy Three categories: • Mechanical/physical e.g. removals by hand (divers), mechanical harvesting or the creation of physical barriers • Chemical - e.g. chemical dosing, toxic baits, application of an inorganic or organic herbicide, larvicide or other pesticide • Biological – e.g. a target-specific pathogen, parasite, predator, biopesticide, genetic manipulation, reproduction manipulation or habitat modification (e.g. salinity change by salt dosing or freshwater inundation).

8. Approaches to Control

9. Mechanical Control • Labour-intensive and often expensive -especially where there are dense infestations or when an IAS is wide-spread and occurs in remote or inaccessible areas. • Advantage of being target specific and that non-target and environmental impacts are usually minor. • Often the best choice when infestations are small and easily accessible, because individual IAS may be specifically targeted.

10. Chemical Control Involves: • Application of chemicals (agents) directly to water column, sediments or target species • Killing or Sterilising target species • Range of options available for various applications • Legal and safety/health constraints • Limited applicability

11. Biological Control Involves: • Control/eradication of target species by another organism • insect, bacteria, virus • biological product (hormone) • genetic or sterility manipulations • Host-specific pathogen, parasite or predator • Negligible side effects on native species

12. Biological Control Disadvantages: • The time and expense required to identify, screen and test candidate control agents; • The time required for the released agent to multiply and cause the required effect • Uncertainty about the level of control the agent will ultimately bring to bear on the targeted population; • The potential for the agent to exert an unexpected effect on native species or communities; • The population regulation mechanism underlying the principle of biological control, which does not anticipate eradication but reduces the invading population density and fitness, with the prey/host or predator/parasite relationship achieving a dynamic balance.

13. Biological Control • Self sustaining methods: • Classical biological control: the introduction of a natural enemy from the original range of the IAS • Habitat management: enhancing the populations of native predators and parasitoids • - Adding to the IAS’ enemies (reared or cultured and released in large numbers) when an outbreak of the IAS has happened

14. Biological Control • 2. Non-self sustaining methods: • Inducing host resistance against the IAS • Biological chemicals. These are chemicals that are naturally produced by living species, and effective against certain introduced species • The use of pathogens, parasites or predators that will not be able to reproduce or survive in the environment • Mass release of sterile males

15. Caution: • It is critical that national legislation provides for tight controls and legal requirements, including risk analysis as an integral part of decision making on whether introduction of a classical biological control agent should be authorised. • Such risk analysis should include all risks, including those for native biological diversity (including endemic species) in the area where the agent would be released. • A control agent approved for one country should hence not automatically be approved for another country.

16. Assessing the Feasibility of Available Options Need to analyse the following: • Background information relating to the species in question. This should include biological, ecological and biogeographic information, as well as the previous invasion history of the species. • Extent of the invasion, including size/density of the population, and geographic area covered. • Available methods for the management option being evaluated. • Case studies of other attempts at managing invasions with similar characteristics or conditions. • Resources available, including man power, equipment and budget • Cost-benefit and risk analysis.

17. Eradication Objectives: • To restore the managed area to the condition it was in before the introduction of the alien species. • To accomplish the above by removing all evidence of the introduced species. • To maintain the managed area free of the introduced species following the eradication programme.

18. Control Control involves reducing the numbers of an IAS to below pre-set levels, or containing its population within a defined area. • Preferable when eradication is not appropriate or feasible • Can be used for short-term relief from impacts, or for ‘holding pattern while other options are investigated • Typically more practical, less damaging options • More affordable in the short-term • But require long-term funding

19. Mitigation and Monitoring Last Resort Strategies • Impact Mitigation • Monitoring / measuring change

20. Key Points • The ultimate goal of IAS management is to minimise threats to biodiversity, human health & welfare and economies • Once a species has become established, there are four options: eradicate, control, mitigate or do nothing • Waiting for all possible information before deciding on how to deal with a newly-reported IAS can be disastrous. • Use all sources of information about the IAS (local, national and international) to help decide how best to manage it • An open and transparent process is more likely to win public and governmental support • One agency or organisation should be responsible for the entire process, with complete authority to make decisions and execute them • Correctly identifying the alien species is the first step in deciding how to manage it

21. Local fishermen have reported that a different fish species has been turning up in their catch during the current fishing season. This species appears to be well-established and occurring in large densities; and its presence has resulted in a decrease in their normal catch. • How would you find out whether it is an invasive species or an invasive alien species, while finding this out what steps can you take? • Would you get the general public to assist? How? • How would you choose/ evaluate a method of control? • If you were to choose biological control, what factors should you consider? • If you were to choose chemical control, what factors should you consider? • What if all attempts to eradicate the species have failed, what can you do?