Horizontal and vertical movements of starry smooth-hound Mustelus asterias in the northeast Atlantic

Abstract

Commercial landings of starry smooth-hound Mustelus asterias in northern European seas are increasing, whilst our knowledge of their ecology, behaviour and population structure remains limited. M . asterias is a widely distributed demersal shark, occupying the waters of the southern North Sea and Irish Sea in the north, to at least the southern Bay of Biscay in the south, and is seasonally abundant in UK waters. There are no species-specific management measures for the northeast Atlantic stock, and the complexity of its population structure is not yet fully understood. To address this issue, we deployed both mark-recapture and electronic tags on M . asterias to gain novel insights into its horizontal and vertical movements. Our data suggest that the habitat use of M . asterias changes on a seasonal basis, with associated changes in geographical distribution, depth utilisation and experienced temperature. We report the first direct evidence of philopatry for this species, and also provide initial evidence of sex-biased dispersal and potential metapopulation-like stock structuring either side of the UK continental shelf. Investigations of finer-scale vertical movements revealed clear diel variation in vertical activity. The illustrated patterns of seasonal space-use and behaviour will provide important information to support the stock assessment process and will help inform any future management options.

Environmental DNA captures elasmobranch diversity in a temperate marine ecosystem

“…We also found the starry smooth‐hound to be most abundant in the winter months. Tagging studies have shown this is a highly migratory species, and consistent with our results, it has a general pattern of overwintering in the English Channel and Bay of Biscay, where pupping takes place, before spending summer months in the North Sea (Brevé et al, 2016, 2020; Griffiths et al, 2020).…”

Metazoan parasite community as a potential biological indicator in juveniles of the starry smooth-houndMustelus asteriasCloquet, 1819 (Carcharhiniformes Triakidae)

“…Second, immature females may be more exposed than immature males to infective oncomiracidia of E. laevis, possibly due to differences in their spatial distribution. Information suggested by E. laevis patterns is in accordance with spatial segregation by sex demonstrated for adults of M. asterias in the Northeast Atlantic, where females disperse across a wider geographic range than males (Brevé et al, 2016(Brevé et al, , 2020Griffiths et al, 2020). Some gill monogeneans such as Mazocraes alosae and Dactylogyrus sp.…”

“…Therefore, these three helminth taxa may constitute useful tags of spatial segregation between males and females at immature stage. Despite recent studies on M. asterias distribution and the demonstration of sex-biased dispersal (Brevé et al, 2016(Brevé et al, , 2020Griffiths et al, 2020), knowledge on immatures is lacking. Predicted suitable habitats of M. asterias immatures generally coincide with those of adults but sex of immatures was not identified in available data (Brefeld and Meyer, 2018).…”

“…Although some recent data occurred on reproduction, growth and seasonal migrations of M. asterias (Farrell et al, 2010a,b; McCully Phillips and Ellis, 2015;Brefeld and Meyer, 2018;ICES WGEF, 2019;Brevé et al, 2016Brevé et al, , 2020Griffiths et al, 2020), it remains a lack of knowledge on various biological and ecological aspects such as population structure, distribution, and behaviour. Surprisingly, the parasitofauna has received very little attention in previous works on M. asterias, despite parasites are ubiquitous natural stressors of great interest to understand population dynamics and to implement management strategies.…”

Yellowfin Tuna Behavioural Ecology and Catchability in the South Atlantic: The Right Place at the Right Time (and Depth)

“…The twilight phase was excluded for this analysis to ensure that only depth during the day and night were compared. Similar methods for the classification of the vertical movements were used in Griffiths et al (2020). Based on the outcome of a two-sample Wilcoxon test, each 24-h cycle was classified as: (1) diel vertical migration (DVM), ( 2) reverse diel vertical migration (rDVM), or (3) no difference in depth.…”