144
A. D. BONEY
on the west coast of Ireland. Harvesting in spring is important because discharge of gametes and casting of the receptacles follows soon
afterwards, and this would account for a 25 to 30% fall in the yield
on a dry weight basis. Printz (1959b) observed that on the Norwegian
coast regeneration did not take place when fronds were cut to within
1 cm of the holdfast and both stumps and holdfasts had rotted away in
many instances. Stump lengths of 5 cm were also inadequate, but with
lengths of 25 cm growth was sufficient to allow almost complete
recovery over the course of 2 years. With older plants or branches this
regenerative growth may take a more protracted time, possibly
because of a lack of active growing points. This slower pace of regeneration may also be a result of a reduced action on the part of growth
substances; in the lateral pits of fronds 8-10 years old there is a marked
decline in the activity of the meristematic tissue. Since the longfronded plants are those preferentially harvested, the stumps which
remain will not recuperate as well as younger branches. Printz suggested that pulling up the plants instead of cutting would be a safer
way of harvesting the frondage, and would ensure more adequate
recuperative growth, since the older fronds would tend to be removed,
and younger branches could then continue growth and development.
Attention has been drawn in recent years to the serious effects of
uncontrolled harvesting on shore fucoid algae (de Virville, 1952;
Printz, 1959b). This is particularly applicable to Aswphyllum, Printz
observed, not only to obtain recuperative growth, but also recolonization of areas of the shore cleared of Ascophyllum. Similar observations
have come from many sources where areas of the shore have been cleared
of their Ascophyllum cover (e.g. Knight and Parke, 1950; Lodge, 1948;
Southward, 1958; Boney, unpublished observations), and lack of
recolonization by Ascophyllum has been observed for periods of 8-1 1
years. On regions of shore densely populated with other fucoid algae,
Fucus spiralis and Fmus vesiculosus have been observed to recolonize
the region cleared. Whilst there is a prodigious output of gametes by
Aswphyllum, this occupies a relatively shorter period of the year
(2-3 months) whereas species of Fucus often produce gametes over a
6-monthly period (p. 137). Oospore settlements in Ascophyllum occur
during the summer months, at a time when rather harsh environmental
factors are operative. The stability of the Ascophyllum cover on sheltered shores is thus mainly due to the relative longevity of the plants,
and this can be radically altered by too severe a cropping. The question
remains as to the part played by the production of gametes and
oospores. Printz (1959b) suggested that by classifying a population into
age groups, an estimate could then be made of the years during which
A. D. BONEY
on the west coast of Ireland. Harvesting in spring is important because discharge of gametes and casting of the receptacles follows soon
afterwards, and this would account for a 25 to 30% fall in the yield
on a dry weight basis. Printz (1959b) observed that on the Norwegian
coast regeneration did not take place when fronds were cut to within
1 cm of the holdfast and both stumps and holdfasts had rotted away in
many instances. Stump lengths of 5 cm were also inadequate, but with
lengths of 25 cm growth was sufficient to allow almost complete
recovery over the course of 2 years. With older plants or branches this
regenerative growth may take a more protracted time, possibly
because of a lack of active growing points. This slower pace of regeneration may also be a result of a reduced action on the part of growth
substances; in the lateral pits of fronds 8-10 years old there is a marked
decline in the activity of the meristematic tissue. Since the longfronded plants are those preferentially harvested, the stumps which
remain will not recuperate as well as younger branches. Printz suggested that pulling up the plants instead of cutting would be a safer
way of harvesting the frondage, and would ensure more adequate
recuperative growth, since the older fronds would tend to be removed,
and younger branches could then continue growth and development.
Attention has been drawn in recent years to the serious effects of
uncontrolled harvesting on shore fucoid algae (de Virville, 1952;
Printz, 1959b). This is particularly applicable to Aswphyllum, Printz
observed, not only to obtain recuperative growth, but also recolonization of areas of the shore cleared of Ascophyllum. Similar observations
have come from many sources where areas of the shore have been cleared
of their Ascophyllum cover (e.g. Knight and Parke, 1950; Lodge, 1948;
Southward, 1958; Boney, unpublished observations), and lack of
recolonization by Ascophyllum has been observed for periods of 8-1 1
years. On regions of shore densely populated with other fucoid algae,
Fucus spiralis and Fmus vesiculosus have been observed to recolonize
the region cleared. Whilst there is a prodigious output of gametes by
Aswphyllum, this occupies a relatively shorter period of the year
(2-3 months) whereas species of Fucus often produce gametes over a
6-monthly period (p. 137). Oospore settlements in Ascophyllum occur
during the summer months, at a time when rather harsh environmental
factors are operative. The stability of the Ascophyllum cover on sheltered shores is thus mainly due to the relative longevity of the plants,
and this can be radically altered by too severe a cropping. The question
remains as to the part played by the production of gametes and
oospores. Printz (1959b) suggested that by classifying a population into
age groups, an estimate could then be made of the years during which