Written evidence submitted by Andrew Brownlow, Director, Scottish Marine Animal Stranding Scheme (SMASS) (MM0013)
Submission to parliamentary enquiry https://committees.parliament.uk/call-for-evidence/2613/
27th May 2022
Background: SMASS is a long running marine mammal surveillance project, continuously funded since 1992 by UK governments and devolved administrations. Its aim has been to investigate the causes of death of stranded marine animals around the Scottish coastline and collect data on threats and pressures impacting marine ecosystem health. I am a veterinary pathologist, have undertaken around 1000 marine mammal necropsies and sit on the IWC Expert Panel for Strandings https://iwc.int/management-and-conservation/strandings/expert-advisory-panel-on-strandings
The Committee is seeking views in the following areas:
Response:
For the purpose of this review, I have limited responses to areas where SMASS have direct experience and/or highlight recent work on key areas.
Purposive killing of marine mammals is likely rare around Scotland and limited to seals historically shot under licence or illegally shot. Although seals shot under licence had to be recorded, it considered unlikely this was fully adhered to and data from stranded cases showed a few (<10) animals each year which appeared to have been illegally shot. Given the slim likelihood shot animals are found and reported, it is possible there was a significant under reporting. It is however not thought that purposive killing is a main reason for population declines, eg harbour seals.
Human behaviours impacting marine mammals can be both direct, acute impacts eg trauma, noise, and longer term, chronic impacts from stressors such as prey depletion, pollution and climate change. Specific details of causes of death can be found in the SMASS annual reports : https://strandings.org/publications/
Direct human behaviours include disturbance from vessels and acoustic disturbance from a number of impulsive noise sources such as construction, sonar and in specific mid range naval sonar, disposal of underwater explosives and vessel traffic. These impact marine mammal populations by impairing their ability to hear, which in turn impacts their ability to fulfil core behaviours, eg forage, navigate, communicate and avoid hazards. Anthropogenic sounds have been implicated in a number of large stranding events, for example the Kyle of Dunness MSE of pilot whales: http://uk601.directrouter.co.uk/~oxcuojji/wp-content/uploads/2021/05/Kyle_of_Durness_Mass_Stranding_Report.pdf. Better quantification and regulation of impulsive noise activities in UK waters and neighbouring international waters is urgently required.
Marine pollution, notably the continuing high levels of persistent organic pollutants (POP) also appear to be having impacts on marine mammal populations through impairments to immunity and reproduction systems. Impacts are highest in long lived apex predators who can accumulate and concentrate levels up the food webs. Levels of pollutants of most concern , such as PCB’s DDT and metals still currently exceed accepted safe levels in almost all monitored populations of UK Killer whales, Bottlenose dolphins and Common dolphins. There is considerable literature on these impacts generated from analysis of the SMASS and CSIP datasets, as an example however https://doi.org/10.1016/j.scitotenv.2019.134835.
Bycatch and entanglement are significant direct causes of death for smaller cetaceans and seals who become caught in nets and larger whales who become entangled in rope. In Scotland, entanglement is the most serious anthropogenic cause of death for larger whales, usually in either active or discarded creel gear. Entanglements have been recognised by the International Whaling Commission as the most significant marine mammal welfare issue of our time and unfortunately the rate appears to be increasing globally, and specifically in the UK. Our recent study (https://www.scottishentanglement.org/downloads/) suggested that over 95% of entanglements go unreported and are likely of high enough incidence to be having a deleterious impact on humpback whale populations in our waters. There is however good engagement from the creel fishing industry to find solutions to this problem and this offers a unique opportunities for the UK to take the lead globally in finding, trialling and implementing effective mitigation strategies.
I hope this brief summary can signpost to a few key areas for consideration based on 30 years of data investigating marine strandings. I would be happy to provide more detailed information should that be required.