Shell Height-To-Weight Relationships for Atlantic Sea Scallops (Placopecten magellanicus) in Offshore U.S. Waters

2012 ◽  
Vol 31 (4) ◽  
pp. 1133-1144 ◽  
Author(s):  
Daniel R. Hennen ◽  
Deborah R. Hart
2006 ◽  
Vol 63 (5) ◽  
pp. 811-821 ◽  
Author(s):  
Bradley P. Harris ◽  
Kevin D.E. Stokesbury

Abstract Shell growth of sea scallops in two commercially productive regions of the Great South Channel (GSC) (41°4′N 69°16′W) was studied using tag–recapture experiments. Commercial fishers captured and returned 9.7% of the 11 704 sea scallops tagged in the southern GSC study area, and 7.9% of the 18 274 sea scallops tagged in the northern GSC study area. Scallop density and shell height distribution were sampled with underwater video in the two study areas. In the southern GSC tagged scallops grew faster, reached larger asymptotic size, and had higher growth performance (Φ′) than in the northern GSC study area. Mean sea scallop density in the southern GSC was 0.117 scallops m−2 (s.e. = 0.01), and 2.601 scallops m−2 (s.e. = 0.28) in the northern GSC. Environmental factors, fishing pressure, and sea scallop density all influence shell growth on a fine geographic scale (1–100 km2) and should be considered in area-specific management strategies, such as that currently used in the USA sea scallop fishery.


1993 ◽  
Vol 71 (5) ◽  
pp. 953-959 ◽  
Author(s):  
Jonathan Grant ◽  
Craig W. Emerson ◽  
Sandra E. Shumway

Passive transport and orientation of sea scallops (Placopecten magellanicus; 27–120 mm shell height) were studied in a laboratory flume to assess flow-mediated control of movement and position on the seabed. Additional experiments were conducted to characterize patterns of sediment transport around the scallop shell in relation to recesses occupied by scallops. The critical shear velocity of scallop transport was not correlated with shell height or other size measures, and most scallops were transported with the ventral shell margin facing downstream. Frontal exposure of scallops to the flow as indicated by fineness (shell height/shell depth) was greater in larger scallops, but when pallial gape was included in fineness (shell height/shell depth + gape)), frontal exposure was not correlated with scallop size. This suggests that variation in the drag component of transport was responsible for the lack of correlation between shell morphometry and critical shear velocity. Sediment transport created a horseshoe-shaped trough around the shell and several smaller erosion–deposition features downstream. The dimensions of sediment transport features were dependent on shell allometry, and it is likely that sediment transport contributes to the formation of scallop recesses typically observed in scallop beds. These results indicate that passive transport of sea scallops has a behavioural component related to gape that is independent of shell size. In contrast, scallop orientation and recessing may be explained by physical processes rather than simply by behaviour. Studies of bivalve hydrodynamics require consideration of living animals in addition to shell specimens and must include conditions of benthic boundary layer flow and sediment transport.


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.


1982 ◽  
Vol 39 (3) ◽  
pp. 499-505 ◽  
Author(s):  
G. S. Jamieson ◽  
H. Stone ◽  
M. Etter

Predation studies in underwater cage enclosures on natural substrates were conducted in 1979 and 1980 to assess the propensity of adult American lobsters, Homarus americanus, and rock crabs, Cancer irroratus, to prey upon sea scallops, Placopecten magellanicus. In 1979, the initial prey by both predator species was large, embedded horse mussels (Modiolus modiolus). In the enclosure containing lobsters, this was followed by lobster cannibalism and, finally, when lobster density was reduced, predation on large sea scallops (80–110 mm shell height). No cannibalism or predation on large scallops occurred in the rock crab enclosure. In 1980, small scallops (40–55 mm shell height) were presented to lobsters and rock crabs; predation occurred regardless of predator density. Large sea scallops and unembedded horse mussels were consumed when crustacean densities approached natural levels. These studies demonstrate that small sea scallops and embedded horse mussels can be readily consumed by lobsters and rock crabs under field conditions, but that natural predation of large scallops by either rock crabs or lobsters is of lesser magnitude.Key words: sea scallops, crabs, lobsters, predation, prey selectivity


2016 ◽  
Vol 19 (1) ◽  
pp. 1 ◽  
Author(s):  
Adi Santoso

A study of the growth of the sea scallop, Placopecten magellanicus, under suspended culture conditions was carried out over a seven month period at a culture site in Graves Shoal, Mahone Bay,Nova Scotia – Canada. Scallop spat were cultivated in pearl nets at a density of 30-35 per net set at four locations corresponding to the surface (7 m) and bottom (14 m) at the outer edge and the center of the site. Shell height was measured at monthly intervals. Environmental conditions represented as temperature and food availability at the surface and bottom over the same period were also monitored. Shell Height growth rate was slightly greater at the surface than at the bottom. At the surface sites growth was greater at the outside (SUROUT) than at the center locations, but at the bottom growth was greater at the centre location (BOTIN). The only significant relationship between shell growth and temperature - food variables was chlorophyll a concentration.  Key words: temperature, food availability, shell height, sea scallop


<strong><em>Abstract. </em></strong>In late 1994, substantial portions of Georges Bank were closed to commercial fishing to assist with stock rebuilding. These areas were Closed Area I (CAI), located on the western portion of the bank, and Closed Area II (CAII), on the eastern portion. After about 5 years of closure, the southern portion of CAII and the central portion of CAI, having exhibited substantial increases in biomass and density of sea scallops <em>Placopecten magellanicus</em>, were reopened to scallop fishing. Before the industry was allowed entry, we conducted surveys to monitor the recovery of benthic habitat and fauna inside both areas. Sampling sites were selected in a paired station design for an inside–outside comparison representative of major habitat types in each closed area; other stations were chosen to survey the remainder of the closed areas. At each station, we examined a suite of biotic and abiotic variables ranging from substrate type to benthos to nekton. Our results suggest few differences between the inside–outside paired stations in both closed areas for nekton and benthic species composition and species richness. Fish abundance and biomass were similar inside and outside the closed areas. However, individuals of species such as skates (<em>Raja </em>spp.), haddock <em>Melanogrammus aeglefinus</em>, and flounders (Pleuronectiformes) were generally larger inside than outside the closed areas. Additionally, habitat type was important in determining the distribution, abundance, biomass, size, and feeding ecology for some of the more benthic-oriented species studied. In CAI, the differences we observed in the suite of biotic metrics are likely a result of the high diversity of habitat types, with many of the habitat types composed of higher-relief material (e.g., cobble, gravel, etc.) in the region. The seabed in the southern portion of CAII is a relatively high-energy sand habitat of low to moderate complexity and has a relatively low vulnerability to trawling and dredging, which may explain why there were less pronounced differences in abundance or biomass across habitat types in that closed area as compared to CAI. Other parts of closed areas on the northeastern shelf may exhibit more obvious changes in the same biological metrics due to the presence of more complex habitats and increased vulnerability to bottom tending fishing gear. Those differences we observed for CAI and CAII may have implications for the population dynamics of commercially valuable benthic species, yet that question remains a major challenge.


2020 ◽  
Vol 77 (5) ◽  
pp. 1992-2002
Author(s):  
Deborah R Hart ◽  
Daphne M Munroe ◽  
Joseph C Caracappa ◽  
Dale Haidvogel ◽  
Burton V Shank ◽  
...  

Abstract We examined evidence for larval spillover (increased recruitment outside the closures) of Atlantic sea scallops (Placopecten magellanicus) due to rotational closures in the Mid-Atlantic Bight using a 40-year fisheries survey time series and a larval transport model. Since the first closure of the Hudson Canyon South (HCS) area in 1998, mean recruitment in the two areas directly down-current from this closure, Elephant Trunk (ET) and Delmarva (DMV), increased significantly by factors of about 7 and 2, respectively. Stock–recruit plots indicate that low biomasses in HCS were associated with reduced mean recruitment in ET and DMV. Simulations indicate that larvae spawned in HCS often settle in the two downstream areas and that model-estimated settlement (based on gonad biomass in HCS and year-specific larval transport between the areas) is correlated with observed recruitment. This study gives strong evidence that the rotational closure of HCS has induced increased recruitment in down-current areas.


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