East Coast Marine Mammal Acoustic Study (ECOMMAS)

ECOMMAS

The ECOMMAS project uses acoustic recorders, known as C-PODs, at 30 locations off the east coast of Scotland, to detect echolocation clicks. At 10 of these locations, a broadband acoustic recorder has also been deployed, to record ambient noise levels, as well as other animal vocalisations.

Since the start of ECOMMAS in 2013, these devices have been deployed at sea every year where they stay throughout the summer, having a battery life of around 4 months. Since 2015, two deployments have been undertaken per year, meaning that there are data covering the period from April to November. In autumn the devices are recovered and prepared for redeployment the following year. The acoustic data are downloaded, processed and analysed.

Results and Outcomes

Data from the broadband recorders have been published as part of the first assessment of baseline underwater noise levels (Brookes, 2017). These data will contribute to the UK’s reporting under the Marine Strategy Framework Directive.

C-POD data are presented in detection-positive days (DPD) and detection-positive hours (DPH). The proportion of DPD (Fig. 3 and 4) and median DPH were calculated for both species at all 30 sites from 2013-20163. The distribution patterns of dolphin and porpoise appear similar from year to year.

Harbour porpoise are detected daily at most sites, with much higher DPH in comparison to dolphins. This is expected due to their greater abundance and wide distribution. Locations with the greatest porpoise detection rates are offshore sites at Spey Bay and Fraserburgh in the southern Moray Firth, and Arbroath. Locations with the lowest porpoise DPH include coastal sites at Spey Bay, Cromarty and Helmsdale.

Generally, the daily detection rate for bottlenose dolphins is lower than for harbour porpoise. At most locations the median dolphin DPH is zero. All moorings at Cromarty have the highest median dolphin detection rates per day.

Sites with low porpoise detections tend to have high dolphin presence. Violent interactions between the two species are known, and the results from these data suggest that they either avoid each other, or harbour porpoise avoid vocalising in areas where bottlenose dolphins are present (Ross et al, 1996).

Data Available

The ECOMMAS dataset from 2013-2016 is available below to download as an excel spread sheet, with accompanying graphs and figures. Included in the spread sheet are the PAM mooring locations, coordinates, dates and times for all 30 sites.

Data is also available below on Marine Scotland Maps NMPi , where dolphin and porpoise distribution can be viewed as time-aware layers. The map layers contain all data and can either be filtered for specific years or played in sequence.

For additional information visit the links below to the ECOMMAS topic sheet and Marine Scotland blog.



References

Hammond, P. S., Lacey, C., Gilles, A., Viquerat, S., Boerjesson, P., Herr, H., ... & Teilmann, J. (2017). Estimates of cetacean abundance in European Atlantic waters in summer 2016 from the SCANS-III aerial and shipboard surveys. Wageningen Marine Research.

JNCC website: https://sac.jncc.gov.uk/site/UK0019808 [accessed 14 August 2017]

Brookes, K. 2017. The East Coast Marine Mammal Acoustic Study data. doi: 10.7489/1969-1

Ross, H. M., and Wilson, B. (1996). “Violent interactions between Bottlenose Dolphins and Harbour Porpoises,” Proc. R. Soc. Lond. 263, 283–286.