Jeff Goddard, USA
Info
Scallops (Placopecten magellanicus) are now one of the most valuable seafoods on the East Coast of the USA!
The scallops spawn in the spring and fall.
Placopecten magellanicus production in Saint Pierre et Miquelon (Northwest Atlantic) has been developed by direct seeding of juveniles on leased land.
However, most of the breeding takes place in water 30 to 70 meters deep, which requires video monitoring to assess growth and survival. In August 2008, a submersible was connected to the surface with a video cable and the observation screen was defined using the video, an altimeter and two lasers. The images were recorded on board on a hard disk and a DVCAM digital video recorder, and the data were georeferenced using VIDEONAV software. Analysis of the videotapes allowed the creation of a thematic database on bottom structure, presence or absence of seeded and wild scallops or predators, and mortality rates. These data could also be interpolated with geographic information systems (GIS) such as Arc View or Adelie software. Preliminary results showed that 70% of the observed scallops were found in seed beds. Growth rate was also estimated by using laser beams on the seafloor, using the height of the camera as a scale. It was measured that the length of P. magellanicus increased between 2 cm and 2.5 cm per year. However, only one campaign was conducted in 2008, and further monitoring is needed to provide advice on cultivation management, such as the relationship between depth and growth rates of scallops, and assessment of dispersal and mortality rates, especially by predators.
There are commercial and developmental scallop (Placopecten magellanicus) farms in Atlantic Canada and New England.
In an experiment designed to evaluate the commercial feasibility of polyculture of scallops with Atlantic salmon (Salmo salar), growth and survival of suspension-grown scallops were measured at two salmon aquaculture sites in northeastern Maine (Johnson Cove (JC) and Treats Island (TI)). Scallop larvae were reared in bead nets and released on ten-net droplines in August 1994.
A ten-net dropline was sampled approximately every four months, and scallops were counted, measured, and weighed.
After one year, shell heights were 53.6 and 56.4 mm, growth rates were 0.11 and 0.12 mm per day, and adductor muscle weights were 3.3 and 4.1 gr, respectively.
These growth rates were comparable to those of scallops grown in suspension culture at a nearby scallop farm and in other areas in Atlantic Canada.
However, lower survival rates were observed in the latter part of the experiment, due in part to heavy fouling, predation, and high stocking density.
Scallop farming at adjacent salmon farm sites offers the possibility of additional income, diversification of the salmon aquaculture industry, and feasibility.
The structure of the eye of Placopecten magellanicus is similar to that of other scallops. Each eye is supported by an optic tentacle whose outer columnar epithelium is transformed into a pigmented iris and a transparent cornea. Beneath the cornea are a cellular lens, a bilayered retina, a reflective argentea, and a pigmented tapetum.
The eyes of P. magellanicus differ from those of other scallops in that the distal retina has fewer receptor cells than the proximal retina and there is no common optic nerve; a lens is not present.
A major criticism of the scallop fishery is that it has killed nearly 1,000 loggerhead sea turtles each year by harvesters.
Since 2015, offshore equipment has been upgraded to include chain mats and so-called turtle deflector dredges (TDDs) to reduce sea turtle deaths.
This has also led to a significant reduction in dead sea turtles.
Like other scallops, Placopecten magellanicus can swim in the ocean to escape enemies if necessary.
Synonyms:
Ostrea magellanica Gmelin, 1791
Pecten brunneus Stimpson, 1851
Pecten fuscus Gould, 1848
Pecten magellanicus (Gmelin, 1791)
Pecten tenuicostatus Mighels & C. B. Adams, 1842
The scallops spawn in the spring and fall.
Placopecten magellanicus production in Saint Pierre et Miquelon (Northwest Atlantic) has been developed by direct seeding of juveniles on leased land.
However, most of the breeding takes place in water 30 to 70 meters deep, which requires video monitoring to assess growth and survival. In August 2008, a submersible was connected to the surface with a video cable and the observation screen was defined using the video, an altimeter and two lasers. The images were recorded on board on a hard disk and a DVCAM digital video recorder, and the data were georeferenced using VIDEONAV software. Analysis of the videotapes allowed the creation of a thematic database on bottom structure, presence or absence of seeded and wild scallops or predators, and mortality rates. These data could also be interpolated with geographic information systems (GIS) such as Arc View or Adelie software. Preliminary results showed that 70% of the observed scallops were found in seed beds. Growth rate was also estimated by using laser beams on the seafloor, using the height of the camera as a scale. It was measured that the length of P. magellanicus increased between 2 cm and 2.5 cm per year. However, only one campaign was conducted in 2008, and further monitoring is needed to provide advice on cultivation management, such as the relationship between depth and growth rates of scallops, and assessment of dispersal and mortality rates, especially by predators.
There are commercial and developmental scallop (Placopecten magellanicus) farms in Atlantic Canada and New England.
In an experiment designed to evaluate the commercial feasibility of polyculture of scallops with Atlantic salmon (Salmo salar), growth and survival of suspension-grown scallops were measured at two salmon aquaculture sites in northeastern Maine (Johnson Cove (JC) and Treats Island (TI)). Scallop larvae were reared in bead nets and released on ten-net droplines in August 1994.
A ten-net dropline was sampled approximately every four months, and scallops were counted, measured, and weighed.
After one year, shell heights were 53.6 and 56.4 mm, growth rates were 0.11 and 0.12 mm per day, and adductor muscle weights were 3.3 and 4.1 gr, respectively.
These growth rates were comparable to those of scallops grown in suspension culture at a nearby scallop farm and in other areas in Atlantic Canada.
However, lower survival rates were observed in the latter part of the experiment, due in part to heavy fouling, predation, and high stocking density.
Scallop farming at adjacent salmon farm sites offers the possibility of additional income, diversification of the salmon aquaculture industry, and feasibility.
The structure of the eye of Placopecten magellanicus is similar to that of other scallops. Each eye is supported by an optic tentacle whose outer columnar epithelium is transformed into a pigmented iris and a transparent cornea. Beneath the cornea are a cellular lens, a bilayered retina, a reflective argentea, and a pigmented tapetum.
The eyes of P. magellanicus differ from those of other scallops in that the distal retina has fewer receptor cells than the proximal retina and there is no common optic nerve; a lens is not present.
A major criticism of the scallop fishery is that it has killed nearly 1,000 loggerhead sea turtles each year by harvesters.
Since 2015, offshore equipment has been upgraded to include chain mats and so-called turtle deflector dredges (TDDs) to reduce sea turtle deaths.
This has also led to a significant reduction in dead sea turtles.
Like other scallops, Placopecten magellanicus can swim in the ocean to escape enemies if necessary.
Synonyms:
Ostrea magellanica Gmelin, 1791
Pecten brunneus Stimpson, 1851
Pecten fuscus Gould, 1848
Pecten magellanicus (Gmelin, 1791)
Pecten tenuicostatus Mighels & C. B. Adams, 1842
