Influence of Density and Depth on the Growth of Juvenile Sea Scallops (Placopecten magellanicus) in Suspended Culture

1993 ◽  
Vol 50 (9) ◽  
pp. 1857-1869 ◽  
Author(s):  
Jean Côté ◽  
John H. Himmelman ◽  
Michel Claereboudt ◽  
John C. Bonardelli

We examined the influence of depth and stocking density on the growth and survival of juvenile sea scallops (Placopecten magellanicus) in suspended culture at Gascons, Baie des Chaleurs. An increase in density greatly reduced the growth of the shell, adductor muscle, and other tissues, possibly because of lower food availability and diminished space. Growth was also influenced by depth and was greater at 9 m than at 21 m. However, the effect of depth was largely masked by the effect of stocking density and fouling of pearl nets. The pattern of seasonal variations in growth varied with the parameter used to quantify growth, and the changes were correlated with temperature and with chlorophyll a in one size fraction (0.7–5 μm). Survival was high at all depths and densities studied. Maximum growth was obtained at a density of 50 scallops∙net−1. However, the growth was only slightly reduced at 100 scallops∙net−1 and thus, this would be an ideal stocking density for growing scallops commercially if the objective is ear-hanging or bottom-seeding after 1 yr of suspended culture.

1997 ◽  
Vol 54 (4) ◽  
pp. 907-913 ◽  
Author(s):  
D J Douglas ◽  
E R Kenchington ◽  
C J Bird ◽  
R Pocklington ◽  
B Bradford ◽  
...  

Sea scallops (Placopecten magellanicus) were fed Pseudo-nitzschia multiseries (formerly P. pungens f. multiseries, Nitzschia pungens f. multiseries) cells of high domoic acid (DA) content (4.0-6.7 pg DA cdot cell-1) for 22 days, followed by 14 days of feeding with nontoxic microalgae. DA was incorporated within 24 h by the scallops, with increased uptake after 6 days, and was concentrated in tissues in the following order: digestive gland >> remaining soft tissue >> adductor muscle. A maximum DA concentration of 3108 mu g cdot g-1 was recorded in the digestive gland, approximately 150 times the regulatory limit (20 mu g DA cdot g-1) and among the highest levels observed in bivalve molluscs; however, only trace amounts, 0.7-1.5 mu g cdot g-1, were found concomitantly in the adductor muscle. At the end of the exposure period, 50.9% of the DA that had been supplied to the scallops had been incorporated into the tissues. Concentrations in the digestive gland 14 days after termination of the toxic diet remained high, 752 mu g DA cdot g-1. Throughout the experiment, there was no sign of illness or mortality attributable to high DA loading, although the destructive sampling of animals did not allow us to assess the effects of the toxin in the longer term.


2021 ◽  
Vol 20 ◽  
pp. 100684
Author(s):  
Struan Coleman ◽  
Caitlin Cleaver ◽  
Dana Morse ◽  
Damian C. Brady ◽  
Thomas Kiffney

1983 ◽  
Vol 40 (3) ◽  
pp. 313-318 ◽  
Author(s):  
G. S. Jamieson ◽  
R. A. Chandler

Levels of Gonyaulax excavata toxin in sea scallop (Placopecten magellanicus) tissues were monitored in eastern Canada on a monthly basis between 1977 and 1981. All tissues but the adductor muscle were found to be highly toxic in Bay of Fundy scallops, with negligible toxicity observed in scallops from Georges Bank, the outer Scotian Shelf, and Northumberland Strait scallops. Level of Bay of Fundy toxicity was much higher than previously observed (maximum digestive gland toxicity: 150 000 μg/100 g in March 1978), and recent average monthly toxicity for Bay of Fundy scallop roe ranged from 184 to 286 μg/100 g. Considerable fluctuation in toxicity can occur between adjacent months, and peak toxicities in sea scallops occur during fail and winter months. Scallop roe fisheries should be permitted to be established for scallops fished from the northern part of Georges Bank and Northumberland Strait. However, a closed zone for scallop roe should be established in the Bay of Fundy and adjacent Scotian Shelf.Key words: scallop, PSP, Gonyaulax, Placopecten, mollusk


2001 ◽  
Vol 52 (8) ◽  
pp. 1413 ◽  
Author(s):  
Phil J. James ◽  
Lennard J. Tong ◽  
Megan P. Paewai

The effects of stocking density and the presence of shelter on the growth and mortality of early juvenile spiny lobsters, Jasus edwardsii, were determined over periods of 118 and 162 days respectively. Growth in length and weight were significantly slower with increasing stocking densities from 50 to 200 m–2, but overall mortality rates were very low and exhibited no difference amongst the densities tested. Conversely, shelter appeared to help to maintain high survival rates in early juvenile lobsters but had no effect on growth throughout the experiment. For maximum growth and survival in a commercial aquaculture operation, densities of 50 to 100 m–2, and adequate shelter would be recommended for early juvenile spiny lobsters. The implications of these results are discussed in relation to aquaculture of this species.


1994 ◽  
Vol 108 ◽  
pp. 119-132 ◽  
Author(s):  
CW Emerson ◽  
J Grant ◽  
A Mallet ◽  
C Carver

1987 ◽  
Vol 44 (1) ◽  
pp. 91-98 ◽  
Author(s):  
J. F. Uthe ◽  
C. L. Chou

Over 90% of the total cadmium in the soft tissues of sea scallops (Placopecten magellanicus) was in the digestive gland with less than 1% in the adductor muscle. The amount of cadmium in the digestive gland was significantly related to shell height. Shell height was superior to age as an independent (predictor) variable due to difficulties in ageing scallops. Based on these relationships, scallops of approximately 100 mm shell height were selected to study interregional differences. Neither cadmium concentration nor burden could be used to identify contaminated areas. The ratio of digestive gland cadmium to that in the adductor muscle was lowest for scallops from Chaleur Bay, which had received substantial anthropogenic cadmium input, and for scallops that had been starved for approximately 14 mo. We suggest that the high tissue cadmium levels in scallops from Georges Bank and Browns Bank are not due to contamination from anthropogenic or natural sources but rather reflect feeding and the nutritional inadequacy of the diets. Conversely, the high levels of cadmium input to Chaleur Bay were not reflected in high tissue concentrations or burdens in scallops.


1979 ◽  
Vol 30 (1) ◽  
pp. 25 ◽  
Author(s):  
AJ Butler ◽  
FJ Brewster

Fourteen random samples of Pinna bicolor were collected over a period of 31 months from 6 m depth in Gulf St Vincent off Edithburgh, South Australia. The length-frequency distributions suggest that: P. bicolor larvae settle in spring but with variable success; growth of newly settled young is rapid over summer; by age 1 year their modal shell length is about 20 cm; by age 2 it is about 26 cm; they may survive substantially longer than 3 years so that a length-class of mode c. 35 cm is always present and is composed of several age-classes not necessarily equally represented. These suggestions are corroborated by limited data on adductor muscle scars, the development of epibiota on the shells, and the growth and survival of tagged animals over 9 months.


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