Sandeel Surveys in the East Coast
MRV Alba na Mara Programme
Duration: 5-18 December 2019
- Sandeel dredge × 2 (modified 4′ scallop dredge with 6″ teeth and spare toothbars) with towing bar and camera attachment.
- TV camera.
- Minilogger (or equivalent).
- To determine the abundance, length and age of sandeels in the sediment from regions east of the Firth of Forth and around Turbot bank.
- To collect and preserve samples of marinus, specifically i) all 0-group sandeels (size to be estimated from age/length keys of sampled catches) not required for age determination; ii) 100 age-1 individuals from each of the northerly and southerly sub-regions.
- To determine the sex and maturity stage of all sandeels selected for ageing.
All required gear will be loaded onto the vessel on 2 December. Scientific staff will be transported to Leith to join the vessel on 5 December.
Two regions of historical importance for sandeel fishing will be surveyed (see Figure 1). In the first half of the survey a series of eight dredge stations to the east of the Firth of Forth will be sampled following the protocol established in 1999. A modified scallop dredge will be used to catch sandeels buried in the substrate at the priority stations given in Table 1 and Figure 2. Further stations in this region will be sampled if time permits. In the second half of the survey, the dredge will be deployed at stations 20-36 in the Turbot bank region (Table 1, Figure 2). Ideally, five repeat tows will be conducted at each station although this may be reduced to a minimum of two if catch quantities are low or available time is limited. Dredge duration will be approximately ten minutes at a towing speed between two and three (ideally 2.5) knots.
In addition, if time and weather allows, 1-2 new stations will be considered off Stonehaven to add a sandeel recruitment dimension to the SCObs time series.
At each dredge station, all sandeels will be identified to species level, measured, and otoliths (5, 8 or 10 depending on length strata, per half centimetre) will be taken for age determination (Objective 1).
All 0-group sandeels will be retained and frozen individually for later analysis. Sub-samples of 100 age-1 (size to be determined from age-length keys of sampled catches) A. marinus will be taken from the northerly (latitude > 57°N) and southerly (latitude < 57°N) sub-regions (objective 2).
Sandeels selected for ageing will be hand stripped and assigned a maturity stage based on a simple three-point scale (I = immature/indeterminate sex; MM= mature male; MF = mature female). Immature individuals will be individually frozen for further dissection and assigned to 1 of 2 stages (IM =Immature male or IF= Immature Female). (objective 3).
- Marine Scotland Website
- Marine Research Vessel Alba na Mara Topic Sheet
- Marine Scotland Science Topic Sheet