RV Lough Foyle LF/11/98

Cruise summary report

Cruise Info. 
Ship name (ship code)RV Lough Foyle (74LG)
Cruise identifierLF/11/98
Cruise period1998-03-09 — 1998-03-19
Port of departureBelfast, United Kingdom
Port of returnBelfast, United Kingdom
ObjectivesDemersal fish survey
1. To obtain information on spatial patterns of abundance of different size- and age-classes of demersal fish in the northern Irish Sea.
2. To obtain abundance indices for the ICES assessments of whiting, haddock, cod and herring.
3. To quantify external parasite loads in whiting and cod, by area.
4. To collect data and samples of sprat and juvenile herring for population/feeding study.
5. To collect samples of flatfish for a feeding study at Port Erin Marine Laboratory.
6. To record quantities of marine litter in trawl catches.
7. To collect tissue samples from cod for genetics study at the University of Hull.
8. To collect samples of dabs for contaminent analysis.

The species composition at the catch at each station was determined, and length frequencies were recorded of each species. Sub-samples of cod, whiting, haddock and hake were taken for the removal of otoliths for ageing. The level of infestation of whiting and cod by external parasites was estimated from the length-frequency and biological samples collected at each station. Pelvic fin tissue was removed from mature and immature cod and preserved in ethanol of DNA analysis. A sample of the remaining dabs and the other flatfish species was frozen for a feeding study at Port Erin Marine Laboratory. Samples of sprats and juvenile herring were taken for analysis of diet and population structure.
Chief scientistMike Armstrong (Department of Agriculture for Northern Ireland), Richard P Briggs (Department of Agriculture for Northern Ireland)
Cruise reportRV Lough Foyle LF/11/98 cruise report lf11_98.pdf (0.31 MB) 
Ocean/sea areas 
GeneralIrish Sea and St. George's Channel
SpecificIrish Sea and North Channel
Track chartsRV Lough Foyle LF/11/98 cruise track — lf11_98track.pdf (0.02 MB) 
Contaminants in organismsQuantity: number of hauls = 44
Description: Samples of large dabs from the hauls were collected at selected stations and frozen for contaminant analysis.
Biology and fisheries 
Demersal fishQuantity: number of specimens = 2292
Description: A commerical Rockhopper trawl fitted with a 20 mm (stretched mesh) liner in the cod-end was towed over 3 nautical miles where possible. 396 cod, 1100 whiting, 750 haddock and 46 hake were analysed for length, mass and maturity and age.
Demersal fishQuantity: number of samples = 200
Description: DNA tissue samples were collected from 100 cod from the western Irish Sea and 100 from the east.
Demersal fishQuantity: number of hauls = 44
Description: Length measures were carried out on all fish species at each station. Catch weights were recorded for most invertebrates.