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Kwon, Inyeong,Kim, Taeho The Korean Society of Fisheries and Ocean Technolo 2015 수산해양기술연구 Vol.51 No.1
The common octopus, which has a high growth rate and high market price, is a prime candidate for commercial marine aquaculture operations. We evaluated the effectiveness of two types of shelters (pipe and tire types) for juvenile common octopus growing out in flow-through seawater tanks. Growth rates were evaluated in two experiments. The first experiment (Experiment 1) ran for 72 days, and the second (Experiment 2; replicated) ran for 46 days. Each trial included 40 octopuses fed a diet of frozen sardine (Sardinops melanostictus) and swimming crab (Portunustri tuberculatus) at 3-8% of body weight once every 3 days. In the two experiments, the respective specific growth rates were 0.3 and 0.04%/day in pipe-type shelters and 0.00 and 0.88%/day in tire-type shelters, while the respective percentage survivals were 80 and 80% in pipe-type shelters and 70 and 90% in tire-type shelters. Shelter type had little influence on the growth rate (P < 0.05).
Shelter material and shape preferences of the sea cucumber, <i>Apostichopus japonicus</i>
Kwon, Inyeong,Lee, Kyounghoon,Kim, Taeho Elsevier 2019 Aquaculture Vol.508 No.-
<P><B>Abstract</B></P> <P>The purpose of this study was to determine the physical properties of shelter design that could enhance sea cucumber cultivation. The structural material (PVC, cement mortar, and porous cement mortar), hole shape (triangle, square, and circle), and hole size (0.0014, 0.0025, and 0.0079 m<SUP>2</SUP>) of shelters were analyzed to determine sea cucumber preferences. Ninety sea cucumbers were used (30 individuals per body size group) and the initial weights were 20.56 ± 4.97 g, 60.80 ± 6.05 g, and 115.80 ± 9.13 g for small, medium, and large sea cucumbers, respectively. Changes in behavioral characteristics in relation to body weight at 10, 15, and 20 °C were also analyzed. Additionally, movement characteristics on surfaces of varying degrees of roughness (a. PVC [0.68–0.9 mm], b. cement mortar [1.5–1.8 mm], and c. porous cement mortar [2.0–2.2 mm]) were determined using particle image velocimetry (PIV) and 2D velocity fields. By day, we observed that sea cucumbers were attached to the inside of circular holes (<I>P</I> < 0.05). Sea cucumbers were attached to shelters made of cement mortar (average 10) > porous cement mortar (average 8) > PVC (average 6), regardless of water temperature or body weight. The preference for sheltering was higher in the small- and medium-size sea cucumber groups than in the group of large-size sea cucumbers. Most sea cucumbers attached to the shelters were in the weight range 20–60 g. The average distances moved by the small, medium, and large sea cucumbers were 1.501, 1.475, and 1.310 m, respectively, and their movement speeds (×10<SUP>−3</SUP> m/s) were 0.181, 0.289, and 0.269, respectively, regardless of water temperature. The movement speed of the sea cucumbers was the fastest (0.373 × 10<SUP>−3</SUP> m/s) at 20 °C. The PIV measurements showed that different velocities and forces were generated when the sea cucumbers moved to shelter materials of varying degrees of surface roughness (force: PVC > porous cement mortar > cement mortar). The sea cucumbers produced the greatest amount of force when moving over smooth surfaces, such as PVC. The smaller the sea cucumber, the less they were affected by temperature change.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The effects of different shelter properties on the behavior of sea cucumbers were investigated. </LI> <LI> The movement distance and speed of sea cucumbers were measured using cameras, software, and particle image velocimetry. </LI> <LI> The shelter preference was higher for small and medium sea cucumbers than for large ones. </LI> <LI> Different forces were generated when the sea cucumbers moved over shelter materials of varying roughness. </LI> </UL> </P>