Echinorhinus brucus (Bonnaterre, 1788)

Mollen, Frederik H. & Iglésias, Samuel P., 2023, An inventory of Bramble sharks Echinorhinus brucus (Bonnaterre, 1788) (Elasmobranchii, Echinorhinidae) in natural history collections worldwide for conservation status assessment, Zoosystema 45 (22), pp. 653-748 : 663

TRENDS IN THE COLLECTION OF E. BRUCUS MATERIAL

The collection of material is first documented from Europe (1680 for the north-eastern Atlantic Ocean; 1827 for the Mediterranean), followed by Africa (1837), South America (1898) and finally North America (1968) where E. brucus records have always been extremely rare ( Table 2A ). For the African continent, the ‘begin dates’ clearly follow the colonial occupation, starting with South Africa (1830s – English occupation), followed by Namibia (c. 1890s – German occupation), and finally western Africa (1950s – French occupation). After the first specimen was recorded in the 17th century, no collection records are known from the 18th century. After this century-long break in collecting, 68 specimens were recorded in the 19 th century, followed by 81 specimens in the 20 th century. Since the beginning of the 21st century, only 10 specimens have been collected to our knowledge ( Table 1C ). For another nine specimens, the collection date is unknown. Exactly 338 years span between the most ancient (1680) and the most recent collection records (2018), resulting in an average collection rate of almost 0.5 specimens per year (n = 169). This average doubles to more than 1.1 specimens each year if the large gap between the first (1680) and the second (1827) specimen is not taken into account. The period between 1870 and 1880 is the most productive decade, with an average collection rate of 2.0 specimens per year. This first peak in the number of individuals that were collected is mainly due to European records ( Fig. 4A, B ). Both for the Mediterranean Sea and the north-eastern Atlantic Ocean, collection rates started to increase rapidly in the 1860s, with an absolute peak in the 1870s and 1880s respectively. As fast as the collection rates increased, these rates decreased again in the following decades. The collection of ‘new’ specimens from European waters became quite rare from the 1920s onwards. Possible collection biases can be observed in the 1910s and the 1940s, during the First and the Second World War respectively. As a result of the latter, some museum collections also suffered great losses, including Bramble sharks. Nevertheless, some specimens that were destroyed or got lost, remain documented to date (e.g. MSNM 2008, Entry 123; Fig. 29C ). A second peak in the number of individuals that were collected worldwide is situated in the 1980-1990s ( Fig. 4A ), and mainly a result from specimens that originate from American and African waters combined ( Fig. 4C, D ). More detailed analyses of these historic data are beyond the scope of this paper and will be dealt with in a later phase of the Bramble shark Cold Case, when records from all other data sources have been made available. As for now, we can conclude that 64 collection specimens (out of 169 individuals in total) represent new records to the scientific community and provide valuable data such as geographical origin and collection date. As such, the results of this inventory of natural history collections will contribute to conservation issues for this iconic, little-known and endangered shark species.

Figures

FIG. 4. — Numbers of individual Bramble sharks Echinorhinus brucus (Bonnaterre, 1788) in natural history collections worldwide, dated and grouped per decade (this survey, n = 157): A, Global waters (the Atlantic Ocean);B, European waters,including the north-eastern Atlantic Ocean and the Mediterranean Sea;C, American waters, including the north-western and the south-western Atlantic Ocean; D, African waters, including the eastern and the south-eastern Atlantic Ocean.

FIG. 29. — Echinorhinus brucus (Bonnaterre, 1788) in Italian (Genoa, Milan, Pavia and Pisa) collections (continuation): A, B, MSNG 18110 (Entry 122); C, MSNM 2008 (Entry 123); D-F, MSNPV CP1833 (Entry 124); G, MSNTC Pe 0081 (Entry 125).