RV Cefas Endeavour 11/21

Cruise summary report

Cruise Info. 
Ship name (ship code)RV Cefas Endeavour (74E9)
Cruise identifier11/21
Cruise period2021-07-21 — 2021-08-17
Port of departureLowestoft, United Kingdom
Port of returnLowestoft, United Kingdom

1. To carry out a groundfish survey of the North Sea as part of the ICES coordinated IBTS, using a hybrid GOV trawl in order to obtain information on:
a) Distribution, size composition and abundance of all fish species caught.
b) Age – length distribution of selected species.
c) Distribution of fish in relation to their environment.
d) Distribution of macrobenthos and anthropogenic debris.
e) Surface and bottom temperature and salinity data using ESM2 profiler/mini-CTD logger and Niskin Bottle.
f) Length weight & maturity information using individual fish measurements, in support of the EU Data Regulation.

2. Tag and release specimens of starry smooth-hound Mustelus asterias, greater-spotted dogfish Scyliorhinus stellaris, spurdog Squalus acanthias, tope Galeorhinus galeus, common skate Dipturus batis species-complex, and blonde ray Raja brachyura, in support of the ICES Working Group for Elasmobranch Fishes work to inform on stock units for demersal elasmobranchs.
3. To freeze any unusual fish species for subsequent identification / verification in the laboratory, including specimens of eelpout (Zoarces, Lycodes and Lycenchelys), sea scorpions (Cottidae, sub-area IVa only), and any unusual fish species, which may also be used in otolith research.
4. To retain any dead specimens of tope (Galeorhinus galeus) and common skate (Dipturus batis species-complex) for biological studies.
5. Retain any dead specimens of shad and lamprey for biological studies.
6. Collect fisheries acoustic continuously data at four operating frequencies (38 kHz, 120 kHz, 200 kHz and 333kHz), using the Simrad EK60 split beam sounder. The data will contribute to the existing 15 year time series of acoustic data in the North Sea and will be used as part of the Defra funded project Poseidon (MF1112) to monitor changes in mackerel distribution and abundance.
7. Cetacean observations will be recorded where possible and sent to the Sea Watch Foundation.
8. Identification, count, measure and weight all jellyfish caught in GOV trawl will allow the continuation of the North Sea August Jellyfish dataset started in 2012; As the dataset grows from year to year, this should allow the evaluation of changes in jellyfish community and biomass with time.
9. Collect squid egg samples to map spawning grounds. This could be highly relevant in studying squid stock’s structure. Retain any specimens of Loligo (not L. forbesi – keep all if in doubt) and all ommastrephid squids (Illex, Todaropsis, Todarodes) for maturity and age analysis, respectively. 25 Alloteuthis are to be retained for maturity and age analysis.
10. Collect, retain and filter surface water samples from Ferrybox underway water supply every 12 hours (or once a day) for subsequent chlorophyll sampling in support of SLA25.
11. Zooplankton plankton sampling using ringnets to collect samples from the Gabbard smart buoy site.
12. Retain examples of epibenthos from GOV catches across multiple fishing stations. These will be examined for toxins related to PST (Paralytic Shellfish Toxin) to highlight potential areas of concern.
13. Visual examination of livers for liver worm conducted on all cod selected for individual fish measurements over 25cm, work completed for IBTS.

Narrative in attached cruise report.
Chief scientistRichard Humphreys (Centre for Environment, Fisheries and Aquaculture Science Lowestoft Laboratory)
ProjectICES International Bottom Trawling Survey (IBTS)
Coordinating bodyInternational Council for the Exploration of the Sea (ICES)
Cruise programmeRV Cefas Endeavour 11/21 cruise programme endeavour11_21.pdf  (0.26 MB) 
Cruise reportRV Cefas Endeavour 11/21 cruise report endeavour11_21.pdf (7.11 MB) 
Ocean/sea areas 
GeneralNorth Sea
SpecificNorth Sea (ICES areas IVa, IVb, IVc).
Physical oceanography 
CTD stationsQuantity: number of stations = 47
Description: 47 CTD casts with ESM2 profiler
CTD stationsQuantity: number of stations = 47
Description: Salinity samples collected at surface and bottom using niskin at 47 stations
Biology and fisheries 
Phytoplankton pigs (eg chlorophyll, fluorescence)Quantity: number of samples = 24
Description: Surface water chlorophyll filtrations at 24 stations
Demersal fishQuantity: number of hauls = 80
Description: 80 valid stations completed with GOV otter trawl, plus 3 invalid.
TaggingsQuantity: number of specimens = 10
Description: 10 elasmobranchs tagged with Petersen discs.
Other biological/fisheries measurementQuantity: number of samples = 8677
Description: Length distributions of all fish and selected shellfish/cephalopod species at every haul, plus 8677 biological samples, including otoliths collected for ageing purposes for commercial fish