Subject title: Understanding skate bycatch from fisheries observer data in Eastern Atlantic waters
1) Key words: Undulate ray, skates, bycatch, gear types, fisheries management
2) Location: Station Marine de Dinard (MNHN)
3) Experience required: Master 2 with knowledge of fisheries and fish ecology,
experience in using R, good level of English
Supervisors: Sophie Elliott (Dr), Station marine de Dinard, MNHN,
Trancart Thomas (Dr), UMR BOREA, Station marine de Dinard, MNHN
Feunteun Eric (Pr.), UMR BOREA, Station marine de Dinard, MNHN
Team location: Station marine de Dinard
Organisation: Muséum National d’Histoire Naturelle
Duration: six months, starting beginning of 2018
4) Subject overview
Dramatic declines in skate species have been observed over the past century
(Baeta et al. 2010; Ellis et al. 2012; Sguotti et al. 2016). Such declines are largely as a
result of fisheries interactions and habitat degradation, accentua ted by their large
size, slow growth and late maturity (Walker and Hislop 1998; Martin et al. 2010; Silva
et al. 2012). Seven skate species are observed within French Atlantic waters Raja
undulata undulate ray, Raja microocellata painted ray, Raja brachyura blonde ray,
Raja clavata thornback ray and Raja montagui spotted ray, Dipturus batis, common
skate and Dipturus oxyrinchus, longnosed skate. Declines in the undulate ray and the
common skate caused particular concern leading them to be categorised as
‘Endangered’ (2009) and ‘Critically Endangered’ (2006) under the IUCN red list (IUCN,
2017) and was added to ICES’ list of prohibited species in 2009 (ICES 2016).
The prohibition was particularly controversial for the undulate ray within the
channel areas, due to high catch rates (Ellis et al. 2011, 2012, Le Blanc et al. 2014,
Stephan et al. 2015). Based on the feedback from scientific programs carried out
since 2011 in partnership with fishermen, it was decided in December 2013 to remove
the undulate ray from the list of prohibited species. To ensure the sustainable
management of local populations of undulate ray, a small amount of Total Allowable
Catch (TAC) was also allowed in ICES subareas 7-9, with limited bycatch but no
targeted fishing in December 2014 (ICES 2016).
Currently, management measures for skates are generic and a burden on the
fishing industry. By improving our understanding on skate fisheries interactions
targeted management measures could be adopted. Targeted management measures
would not only safe guard these species but also reduce impact to the fishing
The present project involves analysing long term fisheries observer data from
around the Bay of Biscay and the Channel to understand the vulnerability of skates to
different fishing gears by: 1) examining the proportion of skates being captured by
different gear types; 2) investigating any long-term trends in catch 3) investigating
seasonal trends in catch; and 4) understanding whether there are any size-based
differences in catch. To undertake the above good knowledge of R and statistical
analysis is essential since this research will focus on manipulating already collected
Financial support: The hourly rate is set at 15% of the social security, defined by the
Article L.241-3 of the social security code (approximately 554,40 euros/month
based on full time work).
Baeta, F. et al. 2010. Elasmobranch bycatch in a trammel net fishery in the
Portuguese west coast. Fisheries Research 102, pp. 123–129.
Ellis, J.R. et al. 2011. Preliminary observations on the life history and
movements of skates (Rajidae) around the Island of Jersey, western English Channel.
Journal of the Marine Biological Association of the United Kingdom 91(6), pp. 1185 –
Ellis, J.R. et al. 2012. An overview of the biology and status of undulate ray
Raja undulata in the north-east Atlantic Ocean. Journal of Fish Biology 80, pp. 1057–
ICES (2016) Report of the Working Group on Elasmobranch Fishes (WGEF), 15 –24
June 2016, Lisbon, Portugal. ICES CM/ACOM:20. 26 pp. Available at:
The IUCN Red List of Threatened Species. Version 2017-2. Available at:
Martin, C. et al. 2010. Spatio-temporal patterns in demersal elasmobranchs
from trawl surveys in the eastern English Channel (1988–2008). Marine Ecology
Progress Series 417, pp. 211–228.
Sguotti, C. et al. 2016. Distribution of skates and sharks in the North Sea: 112
years of change. Global Change Biology 22, pp. 2729–2743.
Silva, J.F. et al. 2012. Species composition of skates (Rajidae) in commercial
fisheries around the British Isles and their discarding patterns. Journal of Fish Biology
80, pp. 1678–1703.
Walker, P.A. and Hislop, J.R.G. 1998. Sensitive skates or resilient rays? Spatial
and temporal shifts in ray species composition in the central and north -western North
Sea between 1930 and the present day. ICES Journal of Marine Science 55, pp. 392–