SGS Product & Process Certification - Marine Stewardship Council

Bearing in mind the vulnerability to capture of juvenile sea bass, additional measures were
needed to support a higher MLS. Conventionally, a minimum mesh size that effectively
complements the MLS would help fishermen minimise the number of undersized fish they had
to discard from their catch. Catch data from gill nets showed that they are highly selective for
sea bass (Reis and Pawson, 1992), and it was proposed that a minimum mesh size of 90 mm
(stretched mesh, measured knot to opposite knot) be introduced for all enmeshing gears,
chiefly because of the difficulty in identifying a bass gill net fishery. Because fisheries for the
small pelagic species - sprat, Sprattus sprattus, herring, Clupea harengus, mackerel and
pilchard Sardina pilchardus -would not be viable with a 90 mm minimum mesh size, a banned
range of mesh sizes (65 - 90 mm) was proposed for enmeshing nets used in England and
Wales, which would allow these fisheries for continue.
The most radical part of the bass management measures proposed for the UK was a restriction
on fishing activities that were likely to take sea bass in areas where most fish in the local
population were below 36 cm. These came to be known as the bass "nursery areas", in which
juvenile fish of 3-5 years old are found in sheltered or enclosed inshore areas (i.e. estuaries,
inlets and harbours) for most of the year, and where tagging had shown exploitation rates as
high as 50% (Pawson et al., 1987). Prior to the period of ―climate warming‖ in the winters of
1988 - 1990 (Pawson, 1992), the susceptibility of 0-group sea bass to low temperatures in
winter (Lancaster, 1991) meant that potential nursery habitats on the North Sea coast were
unlikely to contain sufficient small sea bass in most years to merit protective measures in
addition to MLS and mesh size controls. The main exceptions are where small sea bass are
attracted to warm water discharged from coastal power stations, such as at Kingsnorth in the
Medway Estuary and Bradwell in the Blackwater Estuary, Essex (Turnpenny, 1988).
A package of technical measures was introduced in England and Wales in 1990, which made it
illegal to land bass