Effect of Initial Stocking Density on Larviculture Performance of the Ocellate Puffer, Takifugu rubripes

Abstract

Depending on the initial stocking density, ocellate puffer larvae exhibit the cannibalism that resulted in high mortality. We aimed to clarify the relationship between stocking density of larvae, mortality, and the effect of density on cannibalism. Ocellate puffer larvae were reared at five different stocking densities between 5 and 25 larvae/L with duplicate 1‐m3 tank for each treatment. Larvae were stocked at 0 d after hatch (d.a.h.), and the experimental cultures lasted for 55 d. In larvae stocked initially at more than 10 larvae/L, cannibalism was evident from 11 to 17 d.a.h., and the survival rate at 55 d.a.h. was less than 15%. The survival rate was 25.5% at 5 larvae/L, and cannibalism was observed from 31 to 32 d.a.h. Consequently, an initial density of 5 larvae/L was the most efficient in terms of survival and the prevention of cannibalism. On the other hand, when cannibalism is still observed at 5 larvae/L, it is necessary to lower the stocking density before the onset of cannibalism.

Mortality structures population size characteristics of juvenile yellowtail kingfish Seriola lalandi reared at different densities

“…Most studies investigating the effect of conspecific density include the cannibalism phase (e.g. Hecht et al 1996, Sakakura et al 1998, Baras et al 2003, Fessehaye et al 2006, Szkudlarek & Zakęś 2007, Kotani et al 2009); and therefore are not directly comparable with the present study.…”

“…Most studies investigating the effect of conspecific density include the cannibalism phase (e.g. Hecht et al 1996, Sakakura et al 1998, Baras et al 2003, Fessehaye et al 2006, Szkudlarek & Zakęś 2007, Kotani et al 2009); and therefore are not directly comparable with the present study.The larval and juvenile mortality rates observed in the present study (approximately 5 to 12% d -1 ) were in the lower range of that reported to occur in the wild for marine pelagic fish (Houde 2002). At the end of the trial there was considerable variation in median weight and mortality within and between treatments, and the mortality rate was so variable that the relative density differences between treatments diminished completely.…”

“…As has been observed with larvae of other fish species, there is considerable inter-and intracohort variation in survival and growth during the early life stages of yellow-tail kingfish (Ebisu & Tachihara 1993, Chen et al 2006, Moran 2007. Conspecific density is an important factor in moderating growth and survival, because it affects the intensity of competition for food and shelter and also the degree of aggression and cannibalism (Smith & Reay 1991, Hecht et al 1996, Kotani et al 2009). This is true both in the wild (Folkvord et al 1994, Sakakura & Tsukamoto 1996, Smith & Fuiman 2003 and under the high-density conditions associated with aquaculture (Hecht & Pienaar 1993).…”

“…Conspecific density is an important factor in moderating growth and survival, because it affects the intensity of competition for food and shelter and also the degree of aggression and cannibalism (Smith & Reay 1991, Hecht et al 1996, Kotani et al 2009). This is true both in the wild (Folkvord et al 1994, Sakakura & Tsukamoto 1996, Smith & Fuiman 2003 and under the high-density conditions associated with aquaculture (Hecht & Pienaar 1993).…”

Relationship between oxygen consumption, growth and survival of larval fish

“…The ocellate puffer larvae were initially stocked at a density of 5 larvae L −1 . Once their total length exceeded 8 mm, the stocking density was reduced to 2 larvae L −1 to minimize cannibalism (Kotani, Wakiyama, Imoto, Suzuki & Fushimi 2009). The larvae were fed rotifers at two concentrations: 5 individuals mL −1 from 2 to 22 dph and 3 individuals mL −1 from 23 to 25 dph.…”