In response to interactions between Iberian killer whales (Orcinus orca) and vessels, wherein the whales ram the rudder, often damaging and even breaking it, rendering the vessel unnavigable, an international workshop, involving killer whale scientists and management authorities, was held in Madrid, Spain, on 6– 8 February 2024. The Workshop was sponsored by the Spanish and Portuguese governments, with the following Terms of Reference:

(1) Exchange knowledge regarding the interactions;

(2) Identify future research needs; and

(3) Develop advice and recommendations for the Moroccan, Portuguese and Spanish governments on how to manage these interactions.

The Workshop recommended, in the event of an encounter, that mariners move away from the whales as quickly as possible, at least 2 to 3km from the area in which the whales were encountered, either toward the coast (in the Gulf of Cádiz and Strait of Gibraltar) or toward an area where rescue can be expedited. Moving away is not guaranteed to end the interaction or prevent damage, but may reduce the latter’s likelihood. Mariners should alert authorities as soon as an encounter begins, which should help with response time for a rescue if needed.

The Workshop also strongly recommended that mariners encountering Iberian killer whales do not use any measures to deter whales that would almost certainly harm the whales. The Iberian killer whales are Critically Endangered on the IUCN Red List and deterrence measures that might cause immediate harm or affect long-term survival or reproduction are illegal under European Union and national laws. Several of these harmful measures have been in use at some level since interactions were first reported in the summer of 2020, and the whales continue the interactions. Thus, they are not only ineffective but may be reinforcing the behaviour and increasing the severity of damage to vessels. Some of these measures are also dangerous for mariners (e.g. firecrackers and electrocution).

In summary, the Workshop recommended that mariners use only methods with no impact on the whales or the environment (e.g. moving away), until research and testing, scheduled to be undertaken as soon as possible, determine the effectiveness and safety of other potential measures discussed by the Workshop (see Annex 4 of the full report).

The Workshop also recommended that mitigation measures that produce sound/noise, should they be authorised, be used only when needed, rather than continuously. Continuous use of any such noise- producing measures may:

(1) Reduce their effectiveness (the whales may become habituated, as they have to many other human- caused sounds in their environment);

(2) Eventually serve to attract the whales, as they learn to identify the continuous sounds/noises with vessels and rudders; and

(3) Harm the whales and other marine life (including bluefin tuna and other commercially targeted fish), as it increases the level of ‘noise pollution’ in the Iberian marine environment.

The effort to manage the ongoing interactions between Iberian killer whales and vessels has been, to date, primarily undertaken by the individual national authorities responsible for maritime issues. The Workshop recommended:

(1) Increasing international collaboration and providing consistent advice and reporting systems throughout the region, including the development of a multi-faceted communications strategy; and

(2) Establishing a small, core, international advisory group with the ability to co-opt experts (including from IGOs such as the IWC and ACCOBAMS) as necessary to provide advice to authorities should they request it on scientific and technical matters, including, inter alia, reviewing mitigation protocols and research projects aimed at improving the scientific basis for advice.

The Workshop highlighted the importance of fully understanding the causes of death of killer whales from this Critically Endangered population. It recommended improving stranding responses throughout the population’s range wherever needed, to maximise the number of complete, rigorous necropsies of any stranded killer whales found. The formation of a task force with specific expertise should be considered by the national authorities, with funding made available to allow rapid response to any killer whale strandings reported. The Workshop noted that ACCOBAMS and the IWC could provide general stranding response advice.

The Workshop strongly recommended that all existing datasets for Iberian killer whales—e.g. for photo- identification, sightings and genetics—be consolidated and that all researchers in the region work in close cooperation and communicate frequently regarding killer whale movements and behaviour. To assist in this, the Workshop further recommended that the governments of Spain, Portugal, Morocco and France (if needed) solicit research proposals (and provide funding where necessary) for the following:

(1) Analysis of existing killer whale genetic samples (improve understanding of killer whale movements in relation to prey);

(2) Analysis of AIS data to get a detailed analysis on distribution of AIS-equipped vessels (to get a better understanding of whale-vessel overlap); and

(3) Improvement of understanding of inter-individual behavioural variation and movement with relation to vessels.

Finally, the Workshop recommended that the development of a CMP (Conservation Management Plan) for this population be considered by range states and the IWC Scientific Committee, in cooperation and consultation with ACCOBAMS. National plans should be taken into account when developing this CMP.