Do seals use noise as a source of information?

Lead Research Organisation: University of St Andrews
Department Name: Biology


Noise is a problem whenever animals collect information from their environment. It can affect them in many negative ways. These include whale strandings in response to Navy sonars, hearing damage, increased stress and the avoidance of areas they would otherwise use. Communication sounds can also be affected by noise when they become less obvious in a noisy environment. While many studies have addressed the question of how animals communicate with each other, we still know relatively little about how they use other sounds they hear. Some work has reported that predators use movement sounds of their prey to locate and catch it. Since many animals can learn about sounds they may use them in even more ways to gather information about their environment. For example, a waterfall may be used as an acoustic landmark to find a foraging site or reflection of ambient noise may be used to detect an object in darkness. These possibilities suggest that there is another side to noise, a positive one that can be used by animals for orientation. The project proposed here will investigate this positive side of noise in seals. Sound travels better in water than in air, while visibility is often low. Thus, positive effects of noise are easier to study in this environment.
The first part of the project will investigate whether seals can use noise that is reflected or blocked by objects to detect the objects themselves. If so, an increased noise level may make objects more detectable to seals. For this, we will train blind-folded seals to report when they detect an object that is presented to them in front of an underwater speaker. We will investigate at what distances the seal is able to detect an object in this way, how loud the noise needs to be and whether the noise needs to come from a particular directions to maximise detection. In the second experiment we want to find out whether seals will spontaneously learn to associate a novel sound source with a specific geographic location. For this, we will install such a noise source near a seal haul-out site and then test how seals from that site react to this noise when the are taken to another location. Will they approach the noise source when searching for their haul-out site, even if it has been moved to another location? Finally, we want to know whether seals in the wild learn about sounds produced by humans when looking for food. Many fish farms use acoustic devices that are supposed to keep seals away. However, many reports suggest that these sounds might attract seals just like a dinner bell. We will install an underwater speaker near a fish farm to see whether the seals are more likely to approach when we play the sounds used on the farm as compared to other control noises. Still looking at foraging, we will also provide captive seals with various sand trays with buried fish, some of which also have fish tags in them that make a sound. These tags are widely used to track fish in the wild. We want to know whether seals learn to associate the audible ping with the food in the tray, so that after a while they seek out trays with fish tags.
Taken together, these studies will inform us about how seals use noise in their environment in a way that might help them rather than disturb them. While the negative effects of noise most likely outweigh any positive sides, it is still important to know both sides of the story. If seals can use ambient noise detect objects, collisions with marine turbines and engines might be less likely than we think. Similarly, the effects of noises that we introduce are important to understand. If we remove an acoustic landmark that we have provided by installing a turbine or other machinery, this might affect animals. Similarly, sounds that we use to track fish or keep seals away may have an attraction effect, which leads to undesirable results for the people using them.

Planned Impact

The main beneficiaries outside of the research community for the project proposed here are the marine industries that introduce noise into the environment. These include the marine renewable energy sector, the oil and gas industry, and fisheries and fish farming. Recent evidence of "corkscrew" injuries to seals - where seals appear to be being drawn in to the propeller systems of vessels using Dynamic Positioning - is an example of a serious impact on industry. Such events curtail acceptance of new proposals, and create barriers to early commercial introduction of new technologies. A direct financial impact of marine mammals on marine turbines is the need to stop them when marine mammals are detected to avoid collisions. Such challenges hinder the unlocking of the marine renewable energy potential in the UK. The proposed research project will provide information on whether phocid seals can benefit from increased noise levels by using it for ambient noise imaging, which would make industrial structures more detectable. It will inform the industry whether pinnipeds start to use novel installations as acoustic landmarks which may require a slow phasing out of existing structures once they have reached the end of their lifespan or a provision of an additional stimulus if installations are temporarily not operational. The potential benefits for the gas and oil industry are the same as for the marine renewable energy sector. In the fishing industry, interactions with seals are common. In Scotland alone, fish farm predation causes an estimated loss of between £4.2 Mio and £30 Mio per annum.The results from the proposed project on how seals react to ADD sounds will directly inform the industry on how best to use the devices or whether to use them at all. Our previous research has shown that they have little effect. The current project will evaluate to what extent they may even attract pinnipeds. Thus, results from this study could directly influence whether traditional ADDs will be used in the future. The optimal use of these technologies will optimize returns for companies and result in effective measures taken to ensure conservation of marine animals. In the education sector, the School of Biology is developing a partnership with the Royal Zoological Society for Scotland to establish a research and educational marine mammals centre at Edinburgh Zoo as an addition to our already successful Living Links display on primates at the zoo. At such a centre and as part of the 600th anniversary celebrations for the University of St Andrews, projects like the one in this proposal will be being showcased to the public, industry, politicians and international sponsors. This proposal complements and leverages these activities to support the national strategy to focus attention on market needs and the applications of enabling technologies and their effects on the environment. Since the proposal does not involve the development of novel technologies but will mainly provide advice on best practice, I estimate that the impact on the industry would occur within a year after each study has been concluded. Two postdoctoral researchers are part of the project. They will learn how to manage support staff needed in this project, present the results of the project at international conferences and contribute to teaching by independently running classes. The University of St Andrews is also a signatory of the concordat to support the career development of researchers, offering career development courses and a mentoring scheme that allows postdoctoral scientists to optimize their career chances. Furthermore, we will use the projects to train postgraduate students from our established MRes course on the biology of marine mammal


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publication icon
Stansbury AL (2015) Can a gray seal (Halichoerus grypus) generalize call classes? in Journal of comparative psychology (Washington, D.C. : 1983)

Description Our findings show how seals use acoustic signals indicating the presence of food in the wild. These include fish or net pingers and acoustic deterrent devices (ADDs) that these animals use to locate prey. In the first experiment we showed that grey seals learn to associate fish pingers with food, which leads to tagged fish being preyed upon more effectively than non-tagged fish. In the second experiment, we moved acoustic deterrent device signals away from fish farms to investigate whether these signals attract grey and harbor seals in the wild. We found that while ADDs have a deterrence effect at close range, they also attract seals to fish farms. In the third experiment we placed pingers around harbor seal haul-out sites for several months and tested whether animals returning from foraging trips at sea use these to find the location of the site. This experiment did not provide evidence for the use of pingers in this context. In a fourth experiment, we tested whether captive grey seals can be trained to use acoustic shadows or reflections caused by objects in the ambient noise field to detect the object. One out of three seals tested was able to use acoustic shadows after an extended training procedure. The other two seals were not successful in this learning task. We concluded that while seals may be able to learn to use such cues, they are not a dominant input used by grey seals to explore their environment. While training animals at the Sea Mammal Research Unit, we also noted that they would copy acoustic signals in their environment. This led us to set up an experiment with the same animals to study their vocal learning skills. We succeeded in training one of two test animals to copy frequency modulation sequences on command, demonstrating vocal learning capabilities in this species. To date, there are two publications published and another four manuscripts in preparation for publication from the work conducted under this grant.
Exploitation Route Our results highlight how signals that are paired with food are a very salient stimulus for seals, while noise giving location or obstacle cues are largely ignored (most likely because seals use their whiskers to detect turbulence and currents that are better indicators of location and objects). The first part is of relevance to any studies using fish pingers to mark fish and to the aquaculture industry when using acoustic deterrent devices. Studies on fish migration or survival should avoid using fish pingers, since our results suggest that these data would be biased by increased predation pressure on tagged fish. This is relevant for scientific as well as commercial or governmental studies or monitoring programs.
The absence of sensitivity to other noise cues showed that added noise in the sea will not help seals to navigate. Thus, added noise away from food will only result in the detrimental impacts shown in previous studies such as masking of communication sounds and potentially hearing damage. It highlights that noise should be considered as a hazard in environmental impact assessments of new developments at sea. This is of relevance to regulators and industry when engaging in marine construction projects.
Sectors Aerospace, Defence and Marine,Agriculture, Food and Drink,Environment,Leisure Activities, including Sports, Recreation and Tourism,Government, Democracy and Justice,Transport

Description Pinger producers have tried to avoid onset clicks when developing signals for pingers.
First Year Of Impact 2017
Sector Electronics,Environment,Manufacturing, including Industrial Biotechology
Impact Types Economic

Description DECC research grant
Amount £197,936 (GBP)
Organisation Department of Energy and Climate Change 
Sector Public
Country United Kingdom
Start 01/2012 
End 12/2012
Title Fish pinger experiment 
Description This database contains information on the foraging behaviour of grey seals in a simulated foraging task. Ten animals were observed in 20 learning and 4 test trials, in which an acoustic pinger indicated the location of prey. 
Type Of Material Database/Collection of data 
Year Produced 2014 
Provided To Others? Yes  
Impact The results from this dataset were published in a research paper (Stansbury et al. 2014) showing that seals use acoustic pinger signals to detect prey. These pingers are widely used in fish mark-recapture studies. Our results demonstrated that the use of these pingers in this context is problematic. 
Description Dehnhardt and Hanke 
Organisation University of Rostock
Country Germany 
Sector Academic/University 
PI Contribution Conceptual discussions about research questions, design of experiment, training of animals
Collaborator Contribution Advice on experimental setup, training of experimental animals, organisaiton of workshop
Impact Manuscript in preparation on the use of acoustic daylight by pinnipeds
Start Year 2011
Description BBC news report 
Form Of Engagement Activity A magazine, newsletter or online publication
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Media (as a channel to the public)
Results and Impact BBC news report on seals using fish tags as an indicator of food. The intended purpose of the acitivity was to inform the public of a new research result that changes how we think about a specific research technique (i.e. tagging fish acoustically).
Year(s) Of Engagement Activity 2014