Workpackages

02.1 Body morphometry

The objective of this workpackage is to deliver metric data of the external body dimensions of the herring sampled.
The central tendencies and variances of the morphometric measurements within the samples originating from each single spawning aggregation (reference collection) will be determined. These will be compared to values derived from other spawning aggregations, to values from the mixed adult non-spawning aggregations and from the aggregations of juveniles. This comparison will be done to validate the hypothesis of a correlation between stock identity and morphometric characters. The degree of this correlation will be determined and it will thus be possible to quantify the relative power of morphometric measurements for stock identification.
The data will be used in comparison to and in conjunction with the data from work packages 2 to 6. The combined data of these WP’s will be used for stock identification by multivariate statistics.

A high resolution digital photo will be made of each sampled fish. A standard set-up for controlled lightning and perspective will be used to ensure the comparability of images and the visibility of the key morphometric landmarks. Photos will be stored and transmitted to Partner 3 for image analysis. About 20 single measurements will be made on each image and a truss network will be applied to each fish based on these measurements. Each sampled individual will be treated as one multivariate observation.

02.2 Otolith shape morphometry

The objective of this workpackage is to deliver metric data on the shape of the otoliths of the herring sampled. These data will be used in comparison to and in conjunction with the data from work packages 2 to 7 for stock identification by multivariate statistics.
The central tendencies and variances of the morphometric measurements from the samples originating from each single spawning aggregation (reference collection) will be determined. These will then be compared to values derived from the other spawning aggregations and to values from the mixed adult non-spawning aggregations. This comparison will be done to validate the hypothesis of a correlation between stock identity and morphometric characters. The degree of this correlation will be determined. It will thus be possible to quantify the relative power of these measurements for stock identification.

Otoliths of all adult fish sampled for the reference collection and from the mixed aggregations will be extracted and sent to Partner 3 for the analysis of their external shape. From each fish an otolith outline will be digitised using a video camera connected to a PC running an image analysis software. An elliptic Fourier series will be fitted and the values of the 4 elliptic Fourier coefficients for the first 20 harmonics will be recorded. Each otolith will be treated as one multivariate observation of 80 variables (4 coefficients x 20 harmonics). One of the two otoliths of each fish will then be sent on to Partner 2 for ageing and the other otolith will be kept with Partner 3 for microstructure analysis (WP05, see Figure 2).

02.3 Meristic analysis – pyloric caeca counts

To use the numbers of pyloric caeca as an aid in tracing the origin of the juvenile and adult herring examined.

Visceral organs will be taken from fresh fish at sea and from market sampling programmes or from formerly frozen fish in port, and sent to Partner 1 (first half of the total sample number from one site) and partner 6 (second half), respectively. When the visceral organs of the herring are being examined for endoparasites, it is necessary to separate the pyloric caeca to search for small helminth parasites on their external surfaces. While this is in progress the numbers of caeca in individual herring will be counted and recorded. Meristic data will be send on to Partner 3 for a combined analysis of morphometric/meristic data for individual herring.

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