Dear colleagues, We are pleased to announce two upcoming publications on the strandings of harbour porpoises in the Sea of Azov:
Vishnyakova, K., Gol’din, Cetacean stranding rate correlates with fish stock dynamics: Research of harbour porpoises in the Sea of Azov. Marine Biology doi: 10.1007/s00227-014-2600-x http://link.springer.com/article/10.1007/s00227-014-2600-x The dynamics of the endangered population of the harbour porpoise (*Phocoena phocoena*) in the Azov Sea is currently unknown. It can be, however, estimated by stranding analysis. In 1999–2014, the porpoise stranding rates were regularly monitored at the southern coast of the Azov Sea, particularly at the uninhabited abraded coast of the Tarkhan Cape. Specifically, the general trends and annual fluctuations in strandings were compared to the catch reports of the Azov anchovy (*Engraulis encrasicolus*), an important prey for porpoises. It was observed that the fluctuations in stranding rates closely correlated with the population dynamics of the anchovy stock. A cosine function, based on the data from 1999–2012, correctly predicted maximum strandings in 2013 and their substantial decline in 2014. The function worked particularly well, when possible biases affecting carcass preservation, such as discovery rate and drift conditions, were reduced. In certain environments and over established time periods, the cetacean stranding rate can be an indicator of population trends. The use of stranding rates as such indicator may be verified by external factors, including the dynamics of prey stocks. Vishnyakova, K., Gol’din, P., Seasonality of strandings and bycatch of harbour porpoises in the Sea of Azov: the effects of fisheries, weather conditions and life history. ICES Journal of Marine Science doi: 10.1093/icesjms/fsu192 http://icesjms.oxfordjournals.org/content/early/2014/11/04/icesjms.fsu192.abstract In this study, we analyse seasonal aspects of harbour porpoise strandings in the Sea of Azov and discuss factors affecting the stranding rate. Data on 633 strandings were obtained from monitoring of a 35-km long area of the south coast of the Sea of Azov in 1999–2013. A distinct peak of strandings fell in July and August: it depended on the bycatch peak and calving season. Stranding rates depended neither on weather conditions nor on the seasonal fishing activities (including IUU fisheries). Moreover, stranding peaks in the neighbouring Black Sea were also tied to the calving season rather than to the fishing activities. We suggest that the seasonal mortality patterns are indirectly determined by nutritional stress: in Atlantic, winter-stranding oceanic populations and summer-stranding inner-sea populations occur that also possibly differ in the seasonal dynamics of body mass, weaning time or duration of mother–calf association, and dentine structure. In a typical summer-stranding population, summer is the season of nutritional stress, parturition, independent foraging of yearlings and lactation of nursing females, which leads to the risky foraging behaviour near gillnets. Another possible factor of increased bycatch is the seasonal habitat preference, corresponding to the gillnet preferences. Therefore, stranding and bycatch seasonality of porpoises can largely be explained by the aspects of their life history and foraging behaviour rather than by weather conditions and fisheries. This supports the time–area closure strategy as an adequate conservation measure, which would consider minimizing the conflict of interest with fisheries. We will be grateful for your comments. You are welcome to contact me: [email protected] , [email protected] On behalf of the authors, Pavel Pavel Gol'din Department of Natural History and Palaeontology, The Museum of Southern Jutland, Lergravsvej 2, 6510, Gram, Denmark
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