et al. 2013). In Andalusia, they are being used in the open sea with floats that allow
them to submerge when a strong storm occurs.
Mussel seeds are attached to a nylon rope (dimensions of 12 m in length and
2.5 cm
2 thick) by winding the seed onto the rope, using a biodegradable cotton mesh.
This mesh decomposes within a few days, but this provides enough time for the
mussel seed to produce a new byssus, with which it has been attached to the rope.
This process is similar to those described by Pérez Camacho et al. 1991in Galicia
(NW Spain).
The pre-ongrowing lasts between 4 and 5 months, and the mussel attains about
40–50 mm in height. After this time, it is necessary to thin out the ropes: from each
of these ropes, an average of three new ropes with transferred mussels are obtained.
This ongrowing period takes about 10 months, and the harvest is carried out when
mussels get a size of 60–80 mm in height. The greatest growth is observed in winter,
and the duration of the culture period is 14 months in Marbella, 16–18 months in
Caleta de Vélez, and 10–12 months in La Linea de la Concepcion. Studies have also
been carried out in Ceuta. Commercial size (> 70 mm) is reached within 10 months
of culture, starting from an initial average size of 45 mm. The highest growth rates
are obtained in July and September. Ceuta can be considered a suitable area for
ongrowing, but it has a limiting factor that is the shortage of seed (in accordance with
JACUMAR).
One of the main problems for the development of mussel farming is the possible
lack of native seed, although in recent years the number of facilities and the
production output has increased, this latter reaching 2250 t in 2014.
Pectinid Culture
King scallop (Pecten maximus) and queen scallop (Aequipecten opercularis) are
simultaneous hermaphroditic species, whereby both the female and the male gonads
mature simultaneously. Black scallop (Mimachlamys varia) shows alternating hermaphroditism, changing sex erratically, with separated sexes.
Pectinid cultivation takes place in three phases: seed collection, detachment of the
seed, and pre-ongrowing and ongrowing of the scallop to commercial size. All
phases of pectinid culture are carried out at sea. Both the collectors for seed
collection and the growing structures are anchored to the longlines.
The scallop seed can be obtained in large quantities from the natural environment.
The collectors are anchored and consist of an outer polyethylene bag (Raschel
knitted type or monofilament type) filled with two Netlon bags inside, since the
larvae at the end of their planktonic life seek a filamentous substrate (algae, hydrozoans, bryozoans) where they can fix themselves by the byssus and carry out the
metamorphosis. These collectors are tied in groups on a rope, forming a line (Cano
and Campos 2003a, b). The outer bag allows the passage of water, larvae, and food
but prevents the seeds from escaping when they break the byssus. King scallop and
queen scallop break the byssus when they reach 13 mm, whereby they are detached
from the inner substrate upon which they are fixed, while black scallops maintain the
20 Aquaculture in the Alboran Sea
673
them to submerge when a strong storm occurs.
Mussel seeds are attached to a nylon rope (dimensions of 12 m in length and
2.5 cm
2 thick) by winding the seed onto the rope, using a biodegradable cotton mesh.
This mesh decomposes within a few days, but this provides enough time for the
mussel seed to produce a new byssus, with which it has been attached to the rope.
This process is similar to those described by Pérez Camacho et al. 1991in Galicia
(NW Spain).
The pre-ongrowing lasts between 4 and 5 months, and the mussel attains about
40–50 mm in height. After this time, it is necessary to thin out the ropes: from each
of these ropes, an average of three new ropes with transferred mussels are obtained.
This ongrowing period takes about 10 months, and the harvest is carried out when
mussels get a size of 60–80 mm in height. The greatest growth is observed in winter,
and the duration of the culture period is 14 months in Marbella, 16–18 months in
Caleta de Vélez, and 10–12 months in La Linea de la Concepcion. Studies have also
been carried out in Ceuta. Commercial size (> 70 mm) is reached within 10 months
of culture, starting from an initial average size of 45 mm. The highest growth rates
are obtained in July and September. Ceuta can be considered a suitable area for
ongrowing, but it has a limiting factor that is the shortage of seed (in accordance with
JACUMAR).
One of the main problems for the development of mussel farming is the possible
lack of native seed, although in recent years the number of facilities and the
production output has increased, this latter reaching 2250 t in 2014.
Pectinid Culture
King scallop (Pecten maximus) and queen scallop (Aequipecten opercularis) are
simultaneous hermaphroditic species, whereby both the female and the male gonads
mature simultaneously. Black scallop (Mimachlamys varia) shows alternating hermaphroditism, changing sex erratically, with separated sexes.
Pectinid cultivation takes place in three phases: seed collection, detachment of the
seed, and pre-ongrowing and ongrowing of the scallop to commercial size. All
phases of pectinid culture are carried out at sea. Both the collectors for seed
collection and the growing structures are anchored to the longlines.
The scallop seed can be obtained in large quantities from the natural environment.
The collectors are anchored and consist of an outer polyethylene bag (Raschel
knitted type or monofilament type) filled with two Netlon bags inside, since the
larvae at the end of their planktonic life seek a filamentous substrate (algae, hydrozoans, bryozoans) where they can fix themselves by the byssus and carry out the
metamorphosis. These collectors are tied in groups on a rope, forming a line (Cano
and Campos 2003a, b). The outer bag allows the passage of water, larvae, and food
but prevents the seeds from escaping when they break the byssus. King scallop and
queen scallop break the byssus when they reach 13 mm, whereby they are detached
from the inner substrate upon which they are fixed, while black scallops maintain the
20 Aquaculture in the Alboran Sea
673