Hey everyone,

My coauthors and I are pleased to announce the publication of a new article 
showing an increase in the detection rate of the Critically Endangered Baltic 
Proper harbour porpoise in Swedish waters.

Owen K, Sköld M, Carlström J (2021) An increase in detection rates of the 
critically endangered Baltic Proper harbor porpoise in Swedish waters in recent 
years. Conservation Science and Practice, e468,https://doi.org/10.1111/csp2.468



Abstract: The Baltic Proper harbor porpoise (Phocoena phocoena) is currently 
listed as critically endangered (CR), with the Static Acoustic Monitoring of 
the Baltic Sea Harbor Porpoise (SAMBAH) project concluding that only ~500 
individuals remain. This population has a distribution that spans the waters of 
nine countries, making regular abundance estimates and management action 
challenging. Given the continued decline of other depleted porpoises, namely 
the vaquita (Phocoena sinus), the question is often raised about whether 
management action would even have a positive impact, or whether it is too late 
for population recovery. When abundance estimates are sparse over time, 
monitoring programs at key sites are likely to serve as the best indication of 
population trends, and may provide an early indication of changes at the 
population level. We compared passive acoustic monitoring data from 12 stations 
that were utilized both in the SAMBAH project (2011–2013) and as a part of the 
Swedish National Monitoring Program (2017–2020) to determine trends in 
detection rates. There was a 29% increase in mean daily detection rate during 
May–October (over the breeding season) between the two study periods. At the 
three stations with the highest number of detections, log linear regression 
revealed a yearly increase of 2.4% between 2011 and 2019 (−4.4–9.6, 95% CI). 
This may be indicative of the beginnings of population recovery, or simply an 
indication that the decline has stalled. The rate of increase is still well 
below what is likely to be possible for porpoise populations, and unlikely to 
buffer against any potential increase in pressures in the future. We therefore 
call for urgent management action to remove threats and protect this CR 
population, the only resident cetacean in the Baltic region, in order to give 
it the best chance of recovery.

The article is open access and available here:

https://conbio.onlinelibrary.wiley.com/doi/10.1111/csp2.468

 If you have any questions please feel free to get in touch.

Kind Regards

Kylie Owen


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