Bräger Z., Staszny Á., Mertzen M., Moritz T., Horváth G. 2017. Fish scale identification: From individual to species-specific shape variability. Acta Ichthyol. Piscat. 47 (4): 331-338.Background. Species identification from recovered fish scales, e.g., from the sediment or stomach contents, has proven to be problematic for clupeid species. To ensure reliable species discrimination within Clupeidae, we attempted to reveal inter-and intra-specific, as well as, the intra-individual variability of scale shape in two sympatric clupeid species the European pilchard, Sardina pilchardus (Walbaum, 1792) and the round sardinella, Sardinella aurita Valenciennes, 1847. Our aim was to test, whether the landmark-based geometric morphometric method is reliable for species identification from mixed samples. Material and methods. The specimens of European pilchard and round sardinella were collected between May and October 2014 from the Gulf of Ambracia, Greece. The scale samples were taken from ten body areas (marked by letters A-J) of 487 specimens in total. A multiple-step analysis was conducted on randomly selected blind samples. The differences between body areas were assessed with canonical variate analysis (CVA) and discriminant function analysis (DFA) to compute generalized Mahalanobis distances (D) and discriminant functions (T 2 ), respectively. Results. The CVA based on the total scale samples showed that in sardinella, all body areas differed significantly from each other (D = 2.54 ± 0.79, P < 0.001) except for one (area I vs. J: D = 22.36, P = 0.085). In pilchard, two body area pairs represented non-significant group pairs (area D vs. G: D = 1.03, P = 0.12; and area F vs. G: D = 1.21, P = 0.06), whereas all other areas were significantly different (D = 2.43 ± 0.88, P = 0.003). At the last step of the blind sampling procedure, all scales were correctly classified by species with an average discrimination rate as high as 96.3%. Conclusion. In contrast to scale identification based merely on morphology, the geometric morphometric method is capable of detecting differences in scale shape from mixed samples that are unattainable with the former approach. Therefore, a more reliable and effective species identification can be accomplished from recovered scales, especially when discriminating species within the same family or genus.
LONG TERM GOALS Beaked whales appear to be specifically sensitive to some acoustic sources, which can lead to mass strandings. The lack of knowledge about the population dynamics and reproductive parameters of these animals impedes the assessment of the population effects of stranding mortalities. The goal of this project is to continue a long-term photo-ID study started in the Canary Islands in 2003, in order to obtain a sufficient sample size for demographic modeling. This information will greatly augment the sparse knowledge of beaked whale population biology, facilitating the assessment of possible population effects of human impacts. OBJECTIVES The overall objectives of the project are the following: 1. To assess the spatial fidelity of beaked whales to the study area in the Canary Islands. 2. To estimate population size and analyze the dynamics of the local populations of Blainville's and Cuvier's beaked whales over a 12 year period. 3. To study medium and long term individual associations and individual site-fidelity. 4. To obtain life history parameters of Blainville's beaked whales from long-term photoID data APPROACH Determining when noise causes biologically significant effects requires making the transition from individual impacts, including mortalities, to population-wide effects. For this to be achieved it is essential to obtain data on vital rates and demographic parameters of the affected species (PCAD model, NRC 2005). Beaked whales (fam. Ziphiidae) are the most common taxa involved in mass strandings recorded in coincidence with naval exercises. However, because of their distribution in deep oceanic waters, they are usually difficult to study. El Hierro (Canary Islands) holds resident populations of Blainville's and Cuvier's beaked whales in deep waters close to the shore (Aguilar de Soto 2006). This allows us to perform low-cost shore-based
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