2.5 Cultivation Technologies, Challenges and Future
Directions in Major Cultured Extractive Species
Below we provide some basic information on the cultivation of red and brown
macroalgae to allow a better understanding of the entire production cycle. Mussel
and oyster cultivation methods are explained as well. However, as this book is
mainly focusing on the future development of extractive species off the coast we do
not go in detail with the complete reproduction of these species and will describe
further the cultivation only with regard to the transfer offshore and its relevance to
modern technical design. Further information into the biology and cultivation can
be gained by reading the literature on fundamental seaweed and bivalve biology
and ecology, such as Kim (2012), Wiencke and Bischof (2012) and Hurd et al.
(2014) for seaweeds, as well as Matthiessen (2001), Gosling (2003) and Shumway
(2011) for bivalves.
2.5.1 Red Seaweeds
2.5.1.1 Pyropia and Porphyra (‘Gim’ in Korean or ‘Nori’ in Japanese)
Although a total of 138 species of Pyropia and Porphyra are currently accepted
taxonomically (Guiry and Guiry 2015), only 4 major species (Py. yezoensis, Py.
tenera, Py. haitanensis and Po. umbilicalis) have been cultivated, mostly in China,
the Republic of Korea and Japan (99.99% of total production) and to some extend
in the USA and Europe (FAO 2016a, b). The culture methods of Pyropia/Porphyra
in these three Asian countries are basically similar, with minor modifications
(Sahoo and Yarish 2005; Pereira and Yarish 2008, 2010). For example, some
farmers use free-living conchocelis for seeding while others use conchocelis on
oyster shells (He and Yarish 2006). Seedlings may be outplanted in the open water
farms using one of three cultivation methods: fixed pole, semifloating raft, or
floating raft (Sahoo and Yarish 2005). The epiphyte control techniques are also
different, based on the cultivation techniques. Most Chinese farms, and some
Korean and Japanese farms use desiccation control methods by exposing the
Pyropia/Porphyra nets to the air to kill epiphytes and competing organisms (e.g.
Ulva spp.), while most Korean and Japanese farmers use the more efficient pH
control method by spraying organic acids onto the nets (Pereira and Yarish 2010;
Kim et al. 2014b) which is, however, more costly. The uncontrolled fouling
organisms reduce the quality of the product. Recent reports suggest that the world’s
largest macroalgal blooms of Ulva prolifera are trapped on rafts of Pyropia farms in
the Southern Yellow Sea of China (Liu et al. 2009; Zhang et al. 2014, 2016) before
moving towards the Qingdao region. The initial propagules may, however,
2 Offshore and Multi-Use Aquaculture with Extractive Species…
29
Directions in Major Cultured Extractive Species
Below we provide some basic information on the cultivation of red and brown
macroalgae to allow a better understanding of the entire production cycle. Mussel
and oyster cultivation methods are explained as well. However, as this book is
mainly focusing on the future development of extractive species off the coast we do
not go in detail with the complete reproduction of these species and will describe
further the cultivation only with regard to the transfer offshore and its relevance to
modern technical design. Further information into the biology and cultivation can
be gained by reading the literature on fundamental seaweed and bivalve biology
and ecology, such as Kim (2012), Wiencke and Bischof (2012) and Hurd et al.
(2014) for seaweeds, as well as Matthiessen (2001), Gosling (2003) and Shumway
(2011) for bivalves.
2.5.1 Red Seaweeds
2.5.1.1 Pyropia and Porphyra (‘Gim’ in Korean or ‘Nori’ in Japanese)
Although a total of 138 species of Pyropia and Porphyra are currently accepted
taxonomically (Guiry and Guiry 2015), only 4 major species (Py. yezoensis, Py.
tenera, Py. haitanensis and Po. umbilicalis) have been cultivated, mostly in China,
the Republic of Korea and Japan (99.99% of total production) and to some extend
in the USA and Europe (FAO 2016a, b). The culture methods of Pyropia/Porphyra
in these three Asian countries are basically similar, with minor modifications
(Sahoo and Yarish 2005; Pereira and Yarish 2008, 2010). For example, some
farmers use free-living conchocelis for seeding while others use conchocelis on
oyster shells (He and Yarish 2006). Seedlings may be outplanted in the open water
farms using one of three cultivation methods: fixed pole, semifloating raft, or
floating raft (Sahoo and Yarish 2005). The epiphyte control techniques are also
different, based on the cultivation techniques. Most Chinese farms, and some
Korean and Japanese farms use desiccation control methods by exposing the
Pyropia/Porphyra nets to the air to kill epiphytes and competing organisms (e.g.
Ulva spp.), while most Korean and Japanese farmers use the more efficient pH
control method by spraying organic acids onto the nets (Pereira and Yarish 2010;
Kim et al. 2014b) which is, however, more costly. The uncontrolled fouling
organisms reduce the quality of the product. Recent reports suggest that the world’s
largest macroalgal blooms of Ulva prolifera are trapped on rafts of Pyropia farms in
the Southern Yellow Sea of China (Liu et al. 2009; Zhang et al. 2014, 2016) before
moving towards the Qingdao region. The initial propagules may, however,
2 Offshore and Multi-Use Aquaculture with Extractive Species…
29