Effect of Protein Source and Concentration on Somatic Growth of Juvenile Green Sea Urchins Strongylocentrotus droebachiensis

Abstract

An important aspect in the development of any aquaculture industry is the maximization of juvenile somatic growth (i.e., body growth) to reduce production time and increase the size of the final product. In this study, green sea urchins Sfrongylocenfrofus clroebachiensis were fed a prepared diet from 4 December 1998 to 10 September 1999 (Le., 280 d) in a laboratory to investigate the effect of protein source (soybean andlor fish), protein concentration (20,30,40, and 50% dry mass) and juvenile size (4-8 mm and 12-20 mm initial test diameter) on somatic growth. A natural diet of Laminwia longicrurus (i.e., kelp) was used as a reference. There was no difference in initial size among the treatments for either the smaller cohort 1 or the larger cohort 2 sea urchins (6.3 mm and 13.8 mm initial average test diameter, respectively) (P > 0.05 for all tests). After 280 d, the sea urchins fed kelp had an average size of 20.7 mm and 24.5 mm (cohort 1 and cohort 2, respectively). The final average sizes of the sea urchins fed the prepared diets, which did not relate to dietary protein concentrations andlor protein source, ranged from 13.2 mm to 16.2 mm (cohort 1) and from 20.4 mm to 22.9 mm (cohort 2), and were significantly smaller than the kelpfed sea urchins (P < 0.05 and P e 0.001, cohort 1 and cohort 2, respectively). All treatments experienced 95% survivorship or greater. Sea urchin size appears to affect growth rate when optimal conditions for growth are available (i.e., diet and water temperature). As water temperatures increased during the summer of 1999, the sea urchins in cohort 1 fed kelp had a significantly higher growth rate (0.069 d d ) than the cohort 2 kelpfed sea urchins (0.052 d d ) (P < 0.05). However, within each cohort, there were no significant difference0 in growth rate (P > 0.05) among the sea urchins fed prepared diets, suggesting sea urchins do not require high concentrations of dietary protein for superior growth, and that plant protein can substitute fish protein in sea urchin diets. Furthermore, the sea urchins fed the prepared diets had poorer test quality and larger gonad yields (13-22%) compared to the kelpfed sea urchins (4.2%) and a wild sample of sea urchins of similar size (4.0%). The results suggest that the sea urchins fed the prepared diets allocated more energy to gonad production, whereas those fed a natural diet allocated more energy toward test production. To address this gap, more research is required to identify the nutritional components required for test growth that were present in kelp, but appeared to be deficient in the prepared diets.Interest for sea urchin aquaculture is growing due to the dramatic decrease in world sea urchin populations, and the subsequent increase in sea urchin market demand and market urice. For sea urchin culture to be successful 'Corresponding author's present address: Office of the Executive Scientific Director -AquaNet. 4160 Marine Drive, West Vancouver, British Columbia. Canada V7V 1N6.

Formulated Feed Supports Weight Gain and Survivorship in Juvenile Sea Urchins Lytechinus variegatus

“…Nestler and Harris (1994), Williams and Harris (1998), and Meidel and Scheibling (1999) suggested that a diet of live kelp, Laminaria species, and an additional source of protein (the bryozoan Membranipora membranacea or mussel Mytilus species, respectively) supported better growth than a diet consisting of kelp alone, suggesting that protein concentration is important for juvenile sea urchin growth. In contrast, Kennedy et al (2005) and Akiyama et al (2001) found no significant differences in growth of juvenile S. droebachiensis or Pseudocentrotus depressus , respectively, for protein concentrations within ranges similar to this study. We hypothesize that the effects of protein on growth may be obscured by the quantity or quality of other nutrients (Kennedy et al 2002) in natural diets or formulated feeds, and further understanding of nutritional requirements of sea urchin juveniles is desirable.…”

Production and economic optimization of dietary protein and carbohydrate in the culture of Juvenile Sea Urchin Lytechinus variegatus

“…Growth among juvenile sea urchins may be maximized at dietary protein levels around 20% or greater (Akiyama et al, 2001; Hammer et al, 2004; Kennedy et al, 2005). Juvenile Pseudocentrotus depressus fed purified diets exhibited highest growth at dietary protein levels between 20-50% and highest feed efficiency at protein levels between 20-40% (Akiyama et al, 2001), indicating that 20% protein may be adequate for juveniles of this species.…”

Effect of dietary protein and carbohydrate levels on weight gain and gonad production in the sea urchin Lytechinus variegatus

“…Somatic growth of S. droebachiensis was maximized at dietary protein levels of 19-20% (Pearce et al, 2002b; Kennedy and Robinson, 2005). Akiyama (2001) concluded that 20% protein was optimal in a purified diet for P. depressus.…”

“…Adequate provision of dietary protein decreases feed intake (Frantzis and Gremare, 1992; Fernandez and Bourdouresque, 1998; McBride et al, 1998; Meidel and Scheibling, 1999; Agatsuma, 2000; Fernandez and Bourdouresque, 2000; Hammer et al, 2004; Daggett et al, 2005; Hammer et al, 2006) and increases growth (Fernandez, 1997; Cook et al 1998; Fernandez and Bourdouresque, 1998; Fernandez and Pergent ,1998; Meidel and Scheibling, 1999; Agatsuma 2000; Akiyama, 2001; Hammer et al, 2004; Hammer et al, 2006a; Taylor, 2006) and roe production (de Jong-Westman et al, 1995a; Fernandez, 1997; Barker et al, 1998; Cook et al, 1998; Meidel and Scheibling, 1999; Pearce et al, 2002b; Hammer et al, 2004; Chang et al, 2005; Schlosser et al, 2005; Hammer et al, 2006a; Marsh and Watts, 2007; Woods et al, 2008) in a number of sea urchin species. However, several studies have hypothesized there is a level of protein level at which growth is maximized (McBride et al, 1998; Kennedy et al, 2005; Senaratna et al, 2005; Hammer et al, 2006a; Marsh and Watts, 2007). …”