Search

Herein, the biometrics, body condition, and veterinary findings from the first stranding of a Cuvier's beaked whale (Ziphius cavirostris; Cuvier, 1823) in Denmark are described. It was an adult male with a single tooth (the right was missing). The animal appeared to be well fed and had a body length of 581 cm and a total weight of approximately 2,500 kg. During dissection, we recorded the mass of the bones, blubber, muscle, and organs, which to our knowledge are the first to be published for this species. The back was covered with linear, parallel seaming likely caused by male male competition. In addition, scattered scars were found in the skin derived from cookiecutter shark (Isistius brasiliensis) bites. Multiple small abscesses were found in the blubber, probably due to parasites. Histopathologically, the lungs were characterized by mild purulent pneumonia, and the liver revealed hepatic steatosis. Clostridium sardiniensis and Paeniclostridium sordellii were observed in the lungs and liver. The gastrointestinal tract contained only traces of food and two smaller pieces of plastic in the first stomach chamber. Nematode parasites were found in the intestines. Sexual organs indicated full maturity. Both kidneys showed moderate infestation, with the nematode Crassicauda crassicauda forming calcified granulomas. The exact cause of death was unknown, but the whale was ill with purulent pneumonia and an agonal septicemia. We did not find any evidence of gas or fat emboli. Furthermore, it can be speculated that storms or noise exposure may have led the whale astray, eventually causing its stranding within the so-called "North Sea Trap." The stranding reported contributed to a pattern of increased Cuvier's beaked whale strandings in the North Sea area, suggesting a recent northerly shift of its range, perhaps due to the climate-induced range shift of its squid prey.

With global increases in anthropogenic pressures on wildlife populations comes a responsibility to manage them effectively. The assessment of marine ecosystem health is challenging and often relies on monitoring indicator species, such as cetaceans. Most cetaceans are however highly mobile and spend the majority of their time hidden from direct view, resulting in uncertainty on even the most basic population metrics. Here, we discuss the value of long-term and internationally combined stranding records as a valuable source of information on the demographic and mortality trends of the harbour porpoise (Phocoena phocoena) in the North Sea. We analysed stranding records (n = 16,181) from 1990 to 2017 and demonstrate a strong heterogeneous seasonal pattern of strandings throughout the North Sea, indicative of season-specific distribution or habitat use, and season-specific mortality. The annual incidence of strandings has increased since 1990, with a notable steeper rise particularly in the southern North Sea since 2005. A high density of neonatal strandings occurred specifically in the eastern North Sea, indicative of areas important for calving, and large numbers of juvenile males stranded in the southern parts, indicative of a population sink or reflecting higher male dispersion. These findings highlight the power of stranding records to detect potentially vulnerable population groups in time and space. This knowledge is vital for managers and can guide, for example, conservation measures such as the establishment of time-area -specific limits to potentially harmful human activities, aiming to reduce the number and intensity of human -wildlife conflicts.

In pelagic species inhabiting large oceans, genetic differentiation tends to be mild and populations devoid of structure. However, large cetaceans have provided many examples of structuring. Here we investigate whether the sperm whale, a pelagic species with large population sizes and reputedly highly mobile, shows indication of structuring in the eastern North Atlantic, an ocean basin in which a single population is believed to occur. To do so, we examined stable isotope values in sequential growth layer groups of teeth from individuals sampled in Denmark and NW Spain. In each layer we measured oxygen-isotope ratios (delta O-18) in the inorganic component (hydroxyapatite), and nitrogen and carbon isotope ratios (delta N-15: delta C-13) in the organic component (primarily collagenous). We found significant differences between Denmark and NW Spain in delta N-15 and delta O-18 values in the layer deposited at age 3, considered to be the one best representing the baseline of the breeding ground, in delta N-15, delta C-13 and delta O-18 values in the period up to age 20, and in the ontogenetic variation of delta N-15 and delta O-18 values. These differences evidence that diet composition, use of habitat and/or migratory destinations are dissimilar between whales from the two regions and suggest that the North Atlantic population of sperm whales is more structured than traditionally accepted.