Photo-ID as a tool for studying and monitoring the endangered Saimaa ringed seal

Abstract

Photo-identification (photo-ID) with camera traps was examined as a non-invasive method for studying and monitoring the endangered Saimaa ringed seal Phoca hispida saimensis. An average of 51 game cameras were set up at shoreline haul-out sites in central Lake Saimaa during the moulting seasons in each of the years from 2010 to 2014. Individuals were identified from their lifelong unique lateral fur patterns. A total of 220 000 digital images of seals were obtained from these game cameras and from digital cameras during this period, allowing 164 individuals to be identified, 43% of which were re-sighted in successive years. In the majority of game camera images, both sides of the seal were shown, and it was possible to determine the sex of the seal. The average distance between sightings of individual seals in different years was 1.6 km, suggesting that Saimaa ringed seals exhibit a high degree of moulting site fidelity. In addition, the results support suggestions of natal site fidelity. We propose that photo-ID sampling based on camera traps, and larger-scale photographic survey of the seals, should be implemented as a population monitoring tool of the Saimaa ringed seal. Further application of the photo-ID technique may facilitate mark-recapture population and survival rate estimates for this threatened seal species and provide significant insights into its life history and social behaviour.

Winter behavior of Saimaa ringed seals: Non-overlapping core areas as indicators of avoidance in breeding females

“…As the Saimaa ringed seal is known for its high degree of site fidelity (e.g., [24]), we assumed that the individual seals use the same home ranges year to year; therefore, neighbors could be investigated even when tracked in different study years. Furthermore, a recent photo-identification study (see [44]) confirmed that all neighboring seals were alive throughout the study period. It may be possible that there were other non-tagged seals in the same areas; therefore, the placenta findings were examined with respect to the breeding density independent from the instrumentation.…”

“…The function of female territoriality during the breeding season has been assumed to be related to resource defense [64]. It is well known that Saimaa ringed seals exhibit high site fidelity [4, 19, 20, 44] and that females are especially philopatric [65]. Therefore, we suggest that a lair site with a sufficient annual snow cover for birth lair creation could be a resource worth of interannual defense by the ringed seal females.…”

“…We suggest that lairs should be handled with caution as an index of animal abundance due to the large individual variation in the number of lairs used and the increasing negative effects of mild winters on the visibility of subnivean lair structures during the censuses. Additional and alternative census methods, such as mark-recapture approaches based on photo-identification [44], should be taken into consideration for the safeguarding of accurate population estimates, particularly during varied climate conditions.…”

“…Ringed seals lose weight during the spring due to reproductive and molting activities [33, 43], and the length measurements of living individuals in field conditions are often inaccurate. Therefore, other age measurement criteria, such as known breeding or the earlier identified as an adult verified by photo-identification data [44], were also used for some of the smaller individuals, which were consequently classified as adults, although their lengths or weights did not fully fit the adult seal criteria [33]. After tagging, seals were released in the vicinity of their capture sites.…”

Photafish system: An affordable device for fish photography in the wild

“…From the early days of taxonomy, species descriptions have been accompanied by various types of visual support that are vital to convey information about the morphology and character states used to distinguish species (Akkari et al 2015, García-Melo et al 2018. Currently, the use of digital images in taxonomy has focused on photo-identification methods (Dala-Corte et al 2016) in studies of large vertebrates (Bertulli et al 2015;Koivuniemi et al 2016;Treilibs et al 2016), amphibians (Sannolo et al 2016), lizards (Sreekar et al 2013;Knox et al 2016), invertebrates (Caci et al 2013, Chim & Tan 2012, fishes (Speed et al 2007;Dala-Corte et al 2016), and bats (Rydell & Russo 2014). Few works, however, have attempted to standardize protocols for field photography to provide images that are taxonomically informative for scientific publications and aesthetically attractive for disseminating knowledge and promoting biodiversity conservation to a broader constituency.…”