WHAT IS SEAMAR?

SEAMAR (Shelf-Edge Advection, Mortality and Recruitment) is a multi-disciplinary study to develop a Bio-Physical Transport Model for the prediction of year-to-year survival during the early life-history stages of the North-East Atlantic sock of mackerel (Scomber scombrus).

This involves using a physical transport model to simulate the drift of the eggs, larvae and post-larvae during their planktonic phase over the first few months of life. At the same time their growth and survival is modelled in response to environmental conditions such as food availability and temperature, as functions of the biological and physical environment.

The aim is that by incorporation of the key biological aspects of the development of the eggs, larvae and post-larvae, we can produce a more realistic simulation of their drift from the spawning grounds to the nursery areas. Essentially, we are studying the differential mortality of the planktonic stages in different areas of their occurrence; and it is during this part of their life cycle that it is suspected that much of the environmental regulation of the size of future recruitment to the adult stock takes place.

The main inputs to the programme are:

• Development of individual-based growth and mortality modules for incorporation into the transport model.
• Sampling to obtain the detailed geographical distribution of the planktonic stages of mackerel in relation to mesoscale hydrographic and biological features.
• Measurements of growth and mortality of the planktonic stages of mackerel as a function of the physical and biological environments.
• Incorporation of the locomotory behaviour of the larvae and post-larvae in modifying their vertical distribution and horizontal dispersion.
• Collection of recruit distribution and abundance data for model validation.