Crabs, lobsters and crawfish
The main fishery likely to be encountered on or
near reef habitats is potting and creeling for crustaceans.
Reefs may be vulnerable to fishing as they are
often surrounded by areas of soft sediment making
recolonisation from surrounding areas difficult.
A variety of types of pots and creels may be used
on or near areas of rocky seabed to catch lobsters
and crabs but there is limited information on their
impacts on reef habitats, communities and species.
A recent study on this issue in the UK noted little
effect during deployment and hauling of pots and,
in general, the habitats and communities investigated
appeared to be relatively unaffected by this type
of fishing. The Ross coral, Pentapora foliacea,
which has a fragile structure and which is thought
to provide important microhabitats for other species,
was the only species found to be damaged after hauling
when pots came into contact with colonies. The seafan,
Eunicella verrucosa, which is slow growing and
thought to be highly vulnerable to damage, was found
to bend under the weight of pots and return to an
upright position once the pots were hauled. No significant
differences in the abundance of monitored species
were observed at the study site after one month=s active fishing. Long-term and cumulative
effects were not investigated as part of this study14.
Impacts on otters are discussed in Section 5.3.
The likely effects of lost pots have also been
investigated. An experimental simulation of lost
parlour pots revealed that they continued to fish
throughout the 270 day period of the study14.
Catch rates were highest during the first month
and there were some differences in the pattern of
capture between the species caught. There was a
slight temporary decrease in catches of brown crab
after the bait was depleted followed by fairly constant
capture, whereas catches of spider crab declined
steadily throughout the period of the experiment.
The condition of the catch in the pots deteriorated
with time, indicated by the increased loss of limbs
from crustaceans and fish with skin damage. A similar
study in British Columbia of pots used to catch
Dungeness crab (Cancer magister) reported
that lost pots continued to attract crabs - catch
rates were as high after 1 year as they were 2 weeks
into the study84. The information to
date suggests that it is clearly possible for catches
to continue for a considerable period and various
management suggestions are made, within the reports,
to decrease ghost fishing.