Cruise inventory

FRV Clupea 0906C Part 2

Cruise summary report

Cruise Info. 
Ship name (ship code)FRV Clupea (74CU)
Cruise identifier0906C Part 2
Cruise period2006-07-13 — 2006-07-20
StatusCompleted
Port of departureMallaig, United Kingdom
Port of returnFraserburgh, United Kingdom
PurposeFisheries
ObjectivesObjectives

1. To investigate the distribution of juvenile herring and sprat through the North and South Minch through bottom, or near-bottom trawling. Species composition and length-frequency distributions of all the fish caught will be determined. Sub-samples will be weighed and otolithed to establish age-length and length-weight relationships. Herring samples will be analysed for sex, maturity, Ichthyophonus and Cryptocotyle lingua infection. Sprat samples will be analysed for Lernaeenicus sprattae, L. encrasicoli and Cryptocotyle lingua infection.
2. To collect stomach samples from both herring and sprat to compare summer feeding patterns to the winter patterns to be established from previously collected samples.
3. To collect viscera samples from herring for possible stock ID.

Narrative

On 13 July, the half-landing, the BT158 was replaced with the modified PT154 net, brought to Mallaig for that purpose.

Clupea left Mallaig at 0800 on 14 July to begin Part 2 of the survey, fishing with the PT154 net close to the ground at the stations established in Part 1 as suitable for this method of fishing with that gear. A CTD and vertical plankton dip were also carried out at each station. Fishing was therefore carried out at stations in both the North and South Minches, finishing around 1600 on 18 July where Clupea made passage to anchorage at Dunnet Bay to await the tide for the Pentland Firth.

During Part 2, a total of 18 pelagic (close to the seabed) tows, 18 vertical plankton tows and 18 CTD deployments were performed. A minilogger attached to the trawl nets was used to collect data on bottom temperature for all hauls, using both the demersal and pelagic nets.

Again, in Part 2, with a new SeaRAM unit, the software problems continued and data were unable to be uploaded to the PC. All CTDs were successful and all data were retained. There were also problems with the NetSonde cable which was damaged on the second haul of Part 2. No splicing kit to repair the cable was available. However, the ship's engineer was able to effect a suitable repair.
The catches were very different in Part 2, with a completely different catch composition to the tows using the demersal trawl. The most obvious difference was the lack of juvenile whiting, Norway pout and poor cod with many more jellyfish retained by the pelagic net. Fewer herring were caught generally (51 kg compared to 109 kg in Part 1); juvenile herring in particular were less apparent. Mackerel were also much less abundant (4 kg compared to 81 kg in Part 1) Sprat catches seemed fairly consistent between the two gears.

In total, four samples of 50 herring (all from the South Minch) and one of 15 herring (from the North Minch) were collected for herring viscera and stomach analyses. Four samples of sprat were taken for stomach sample analysis (n=197), all from the South Minch. No sprats were caught in the North Minch.

Clupea return to Fraserburgh on the afternoon of 19 July, where some of the scientific equipment and samples were offloaded and the scientists left the vessel. Large gear was offloaded on Thursday 20 July.
Chief scientistSteven J Hay (Fisheries Research Services Aberdeen Marine Laboratory)
ProjectMFO1Ta
Coordinating bodyFRS
Cruise reportFRV Clupea 0906C Part 2 cruise report 0906c.pdf — access key 'C' (0.03 MB) 
Ocean/sea areas 
GeneralInner Seas off the West Coast of Scotland
SpecificNorth & South Minches
Measurements 
Physical oceanography 
CTD stationsQuantity: number of deployments = 44
Biology and fisheries 
PhytoplanktonQuantity: number of hauls = 42
Description: vertical plankton tows
PhytoplanktonQuantity: number of hauls = 24
Description: double oblique plankton tows
ZooplanktonQuantity: number of hauls = 24
Description: double oblique plankton tows
ZooplanktonQuantity: number of hauls = 42
Description: vertical plankton tows
Pelagic fishQuantity: number of samples = 5
Description: 4 samples of 50 and 1 of 15 herring collected
Pelagic fishQuantity: number of hauls = 26
Description: demersal tows mainly: whiting, norway pout, sprat and mackerel
Pelagic fishQuantity: number of hauls = 18
Description: pelagic tows including: mainly jellyfish and sprat
Demersal fishQuantity: number of hauls = 18
Description: pelagic tows including: mainly jellyfish and sprat
Demersal fishQuantity: number of hauls = 26
Description: demersal tows mainly: cod
Other biological/fisheries measurementQuantity: number of samples = 4
Description: sprat for stomach content analysis
Other biological/fisheries measurementQuantity: number of samples = 5
Description: 4 samples of 50 and 1 of 15 herring collected