The linear bank systems lying just offshore of the local coastline offers a unique habitat of importance to fish stocks. They comprise well sorted sand, a consequence of wind and wave action which is increased by the shallowing of the water on the bank tops. The shoulders of the bank offer a moderate slope into deeper waters. Whilst the bank crests are mobile, the bank as a whole represents a stable feature with degree of sediment mobility decreasing with depth.

Accordingly bottom living creatures make the sands their home. Few types can survive the mobile crests, but those which do can occupy the niché in surprising numbers, away from the competition of others. These include mysid shrimps and sandeels (small elongated, very mobile fish which burrow in the sand in the day and swim above the bank at night).

Species diversity (number of species) increases down the bank slopes until it merges with different communities based in more muddy habitats on the seabed floor itself. The overall diversity of bank systems themselves is not high. However the represent an additional habitat and add habital diversity to the region as a whole. The biomass (total weight) of mobile organisms on the bank can at times be signigicant. Owing to the mobility of the animals they can be quite difficult to count and locate adding to difficulty in making an ecological assessment.

Various species of fish are attracted to the banks mainly for feeding purposes. These tend to be predators feeding mainly on sandeels e.g. bass, turbot (flatfish) an small eyed ray associated with a range of other species which are more widely distributed? Juvenile turbot in particular are more abundant here than elsewhere, and the adults tend to frequent deeper water. Although a number of ray species exist, the small eyed ray is a specialist feeder on sandeel and therefore frequents sandy ground. Other ray species feed on molluscs, crabs and other fish thereby sharing out resources and reducing competition. Bass are fairly mobile and ubiquitous in season. They focus and switch foods according to availability. Very small bass feed in estuaries, the banks support shoals of medium sized fish with a smattering larger (specimens).

So wherever there is food, you will find fish, and wherever fish are attracted to an area, you will also find fishermen. The banks are a focal point for recreational and commercial fishing activity. By concentrating activity the banks have a higher value than would otherwise be present in the area. It is very difficult to quantify this because recreational activity is not monitored or easily valued, fishermen's commercial landings are usually under declared and valued for tax purposes. Furthermore, if sand was removed by dredging and the habitat declined, it is difficult to asses the extent by which this would adversely influence fish stocks, which are themselves highly variable between years. It is likely to be the case however, that relatively small changes in bank profile, crest height and water depth may have a disproportionate effect on fish stocks. This explains why the South Wales Sea Fisheries Committee has raised concerns over the removal of significant quantities of sand from the bank systems. Once gone, the sand will not come back.

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