Marine Scotland

Clyde Herring Acoustic Survey

October 18, 2017 by No Comments

Duration: 20 October – 3 November 2017

Figure 1: Track executed by MRV Alba na Mara on the Clyde Herring Acoustic Survey October 2012.

Sampling Equipment: PT154, CTD

Objectives:

  1. To conduct an acoustic survey designed to survey both the open and enclosed areas of the Clyde to ultimately provide an estimate of the abundance and distribution of herring and sprat.
  2. To obtain samples of herring and sprat for biological analysis, including age, length, weight, sex, maturity and ichthyophonus infection.
  3. All other species caught will be measured for length and weight to establish a length weight relationship.
  4. CTD profiles will be taken at the end of each trawl.

Procedure:

The survey will be carried out within an area bounded by approximately 55°N to 56°N and 04° 40’ W to 05° 40’ W. Echointegration will be carried out at 38, 120 and 200 kHz.  Data gathered in the hours of darkness will not be used for stock assessment.  Trawling operations will be carried out as and when marks are identified.  Otoliths will be collected from a sub-sample of the herring and sprat to determine age.  The maturity state and. presence of Icthyophonus infection will also be recorded.

A CTD profile will be taken at the end of each trawl.

The track will be similar to that of previous surveys (Figure 1).

TSG data will be gathered during the survey.

The survey will involve following a pre-set survey pattern, at a steaming speed of 8 knots.

Further Information


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