Conclusions and gaps in knowledge
Impacts on bait species
Impacts on non target
Impacts on other
In many cases shoreline species
collection activity is not thought to be incompatible
with nature conservation objectives in marine sites.
Some scientific and site management case studies,
however, demonstrate that habitat damage and alteration,
damage to non-target species, and bird disturbance
and prey depletion may arise from this activity,
particularly if carried out on a large scale. These
are summarised below. In such situations, shoreline
species collection (whether for bait or for food)
may require mitigating action if intertidal nature
conservation objectives are not to be compromised.
Literature review indicates that
habitat damage on sediment shores is likely to be
most serious in low energy environments, where sediments
are poorly sorted (mixtures of stones and mud),
often polluted, and recovery rates from bait digging
can be very slow. Such sites are frequently located
in estuarine areas and other inlets, close to centres
of population, exposed to heavy use by collectors,
and also subject to many other development pressures.
More wave exposed, sandy shores
are not as significantly affected by bait digging,
and the use of bait pumps in these locations appears
to cause negligible damage. Very large-scale use
by mechanical bait dredgers has the potential to
cause significant damage even in these situations.
Some studies of boulder turning
for peeler crabs have demonstrated that serious
habitat damage, particularly on sheltered, stable
boulder shores, can occur when boulders are not
replaced. The effects of wide-scale introduction
of crab shelters in estuaries on habitats and species
have not been studied, but are considered likely
to be significant in some areas. Investigations
are required of the impacts of introduction of crab
shelters into inlets on the sediment habitats occupied
by large numbers of shelters, bird populations,
and crab populations. In particular, the optimum
density of crab shelters, both for minimising habitat
effects and maximising yields should be determined
as a matter of urgency. Shelter density is probably
unnecessarily high in some areas. The effect of
the orientation of shelters (flat versus driven
at an angle into the sediment) should also be examined.
Much of this work might be undertaken, at least
initially, through undergraduate projects.
Impacts on bait
Most populations of bait species
are not threatened by collection, even locally.
Many of the animals used by anglers are common and
widely distributed, with their life cycles and ecology
enabling a quick recovery from low population levels.
Exceptions to this rule are the catworms Nephtys
species and unusual long-lived king ragworm
Nereis virens populations like that studied
in the Menai Strait. Heavy bait digging pressures
may seriously affect the survival of local populations
of these groups.
In the case of the Menai king ragworm,
a single unique population could be endangered without
the controls on this activity planned within the
proposed Marine Nature Reserve. Studies of other
reported populations of unusually large king rag
worms Nereis virens (e.g. in Milford Haven)
are needed to determine whether these also have
the characteristics of those in the Menai Strait,
and whether management of these stocks are necessary.
This could be a useful undergraduate project, modelled
on those carried out in the Menai Strait.
There is very little information
available on the impacts of collection of large
numbers of peeler and softshell crab Carcinus
maenus, and potential means of mitigating these.
Undergraduate projects could compare population
structure in exploited and unexploited areas and
More information is required on
the biology, ecology, and exploitation of the valuable
bait species, the black lugworm Arenicola defodiens,
including survival after tail loss and eversion
of internal organs. Would closure of beds during
breeding periods result in increased levels of recruitment,
and in which habitats do the larvae live? This information
would help to determine the impacts of bait collection
on this species (presently considered to be relatively
small) and establish appropriate bait collection
management regimes, if necessary. Some life cycle
information is apparently already known, but commercially
confidential and unpublished. Field studies might
be undertaken as undergraduate projects, and more
detailed research as a postgraduate study.
Not much is known about the biology
of white ragworms Nephtys species and potential
for mitigation of the impacts of collection of this
genus. Research into captive populations might provide
some useful information (some is likely already
known, albeit unpublished and in confidence), as
well as determining the potential scope for restocking
depleted bait beds of this and other species by
breeding local brood stock in bait farms.
Impacts on non-target
The non-target invertebrates most
affected by bait collection are large, long-lived,
slow-growing infaunal species that may be fragile,
easily damaged by bait diggers and slow to recolonise
areas. Under-boulder fauna, which are dependent
upon a stable and very specialised habitat, are
also severely affected by boulder-turning by collectors
in search of peeler crab. Diverse communities characteristic
of some poorly-sorted sheltered sediments may also
be damaged by bait collection or the introduction
of crab shelters. Mechanical bait dredging causes
a high loss of biomass in areas dredged.
Disturbance of feeding shore birds
caused by the presence of bait collectors on the
shore at low water in some sensitive areas is a
very serious problem. The removal of invertebrate
biomass (bird food) is also potentially significant,
particularly if mechanical dredging takes place.
Most methods of bait collection (probably excluding
bait pumping) may cause significant habitat and
non-target species damage, and all may restrict
the areas of shore available to feeding birds.
Impacts on other
Bait collection activity can incompatible
with certain fisheries - mainly through damage to
intertidal cockle and mussel beds, or increased
access difficulties to shellfish beds.
Habitat damage and alteration may
also be incompatible with some recreational uses,
harbour operations and archaeological heritage.
Problems caused include deterioration in the aesthetic
appearance of dug shores and crab shelters, human
safety, and physical damage to vessels and structures.
Competition between different groups
of bait collectors (anglers vs. commercial
collectors, professional vs.
unemployed commercial collectors, and/or
locals vs. visiting collectors) has sometimes
been reported when over-exploitation of bait stocks
takes place. It can be extremely difficult to resolve
such competition through voluntary agreement or
self-regulation where visitors are involved, and
because of the difficulty of proving a distinction
between commercial and non-commercial activity.
Many bait collectors are in favour of a system for
licensing bait diggers (requiring commercial collection
and sales to be recorded), which should be backed
by resources to implement and enforce licensing
One issue not covered above is
the impact of changing coastal structures on sediment
transport on the shore, by siltation of rocky shores
or baitworm beds, habitat loss and change, and loss
of bait stocks. This was a concern raised by several
anglers and commercial collectors, but is outside
the scope of this project.
Mitigation of these effects, other
than as indicated in the preceding sections, is
possible to some extent through existing codes of
conduct for bait collection, although unfortunately
these are sometimes ignored by a significant number
of collectors. Bag limits have been attempted, with
limited success, to reduce effort and hence environmental
impacts. In a few cases, zonation of incompatible
activities has been introduced, either under voluntary
agreement or backed by legislation. A number of
examples of management to mitigate the impact of
shoreline species collection are presented in Appendix
Artificial culture using local
brood stock may prove to be an important means of
promoting the recovery of over-exploited stocks.
Several individuals consulted during
the preparation of this report expressed a wish
for a licensing or permit system to be introduced
for the regulation of commercial bait collection
and resale, similar to that in place in Maine (see
case study in Appendix II). Such a system would
require retail outlets to record the license details
of all bait collectors from whom bait was purchased,
and the quantities, species and origins of the bait.
The benefit of such a system would be the protection
of bait stocks for anglers and professional bait
collectors from unregistered, unemployed bait diggers.
(The latter are thought to be the source of much
of the damage to bait beds.) Licensing would also
offer improved potential for the assessment and
regulation of commercial collection within the area,
and the promotion to anglers of codes of conduct
for bait collection.