Verification of Atlantic sea scallop (Placopecten magellanicus) shell growth rings by tracking cohorts in fishery closed areas

2009 ◽  
Vol 66 (5) ◽  
pp. 751-758 ◽  
Author(s):  
Deborah R. Hart ◽  
Antonie S. Chute
Keyword(s):  
Shell Growth ◽  
Shell Height ◽  
Annual Growth ◽  
Transition Matrices ◽  
Placopecten Magellanicus ◽  
Sea Scallop ◽  
Growth Increments ◽  
Repeated Sampling ◽  
The Mean ◽  
Shell Rings

We tracked the growth of large cohorts of sea scallops ( Placopecten magellanicus ) at four sites located in areas closed to scallop fishing and compared the observed growth with that inferred from rings on sea scallop shells collected at the same sites. Stochastic growth transition matrices were constructed for each site based on the shell growth increments, assuming annual ring formation. These matrices were used to predict the annual growth of the scallops, which were compared with direct observations of growth obtained by repeated sampling. Additionally, the observed growth of the scallops was used to estimate the parameters of a stochastic von Bertalanffy model for each site, which were used to estimate the mean annual growth increments as a function of starting shell height. These were compared with the mean growth increments on the shells. There was a close correspondence, in most cases, between the observed growth and the growth inferred from the shell rings, implying that the shell rings were formed annually. The lack of fishing mortality in the areas meant that there was no confounding of size-selective fishing with growth and allowed us to track cohorts longer than would otherwise have been possible.

scholarly journals The Influence of Temperature - Food Availability on the Shell Growth of Sea Scallop Placopecten magellanicus (Gmelin, 1791)

2016 ◽  
Vol 19 (1) ◽  
pp. 1 ◽  
Author(s):  
Adi Santoso
Keyword(s):  
Food Availability ◽  
Shell Growth ◽  
Shell Height ◽  
Culture Conditions ◽  
Outer Edge ◽  
Placopecten Magellanicus ◽  
Surface Sites ◽  
Sea Scallop ◽  
Key Words Temperature ◽  
Culture Site

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

scholarly journals Shell growth of sea scallops (Placopecten magellanicus) in the southern and northern Great South Channel, USA

2006 ◽  
Vol 63 (5) ◽  
pp. 811-821 ◽  
Author(s):  
Bradley P. Harris ◽  
Kevin D.E. Stokesbury
Keyword(s):  
Shell Growth ◽  
Shell Height ◽  
Management Strategies ◽  
Height Distribution ◽  
Placopecten Magellanicus ◽  
Geographic Scale ◽  
Sea Scallop ◽  
Asymptotic Size ◽  
The Usa ◽  
Sea Scallops

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.

Seasonal growth pattern in the lichen Pseudocyphellaria berberina in north-western Patagonia

2004 ◽  
Vol 36 (6) ◽  
pp. 435-444 ◽  
Author(s):  
Mayra S. CALDIZ
Keyword(s):  
Growth Increment ◽  
Annual Growth ◽  
Seasonal Growth ◽  
Epiphytic Lichen ◽  
Growth Increments ◽  
The Mean ◽  
Individual Trees ◽  
Nothofagus Dombeyi ◽  
North Western ◽  
Annual Growth Increment

Seasonal growth increments (%) were measured in the foliose epiphytic lichen Pseudocyphellaria berberina in north-western Patagonia. Growth was determined by measuring increase in weight (expressed as percentage of the original biomass) in transplanted thalli. Transplants were either hung freely from wooden frames or attached to tree trunks in a Nothofagus dombeyi forest and then weighed every three months between January 2001 and April 2003. The influence on growth increment of treatment, donor thallus, temperature, and absolute and relative humidity was analysed. Mean annual growth increment after two years, in both treatments was 12±1·07% (±SE). Growth increment was greatest in winter and lowest in summer; the mean winter growth increment was 6±0·50%, representing half of the annual growth, whereas most of the remaining growth occurred during both spring and autumn. Growth increments were similar for freely-hanging lichens and for the transplants attached to tree trunks. Individual trees had no consistent effect on growth while the donor thallus had a significant effect in the first season which then diminished, indicating acclimation in the transplants. Initial transplant weight had no influence on final cumulative growth, nor was there any consistent correlation between one season and another in the growth of transplants. Both transplantation methods proved to be useful for experiments on the growth of P. berberina.

Swimming behavior of juvenile giant scallop, Placopecten magellanicus, in relation to size and temperature

1991 ◽  
Vol 69 (8) ◽  
pp. 2250-2254 ◽  
Author(s):  
J. L. Manuel ◽  
Michael J. Dadswell
Keyword(s):  
Water Column ◽  
Significant Relationship ◽  
Size Range ◽  
Shell Height ◽  
Swimming Behavior ◽  
The Body ◽  
Placopecten Magellanicus ◽  
Body Angle ◽  
The Mean ◽  
Increasing Temperature

Juvenile scallops (shell height 4–35 mm) were stimulated to swim in an aquarium using a whelk, and their swimming was recorded and analyzed using a videocassette recorder. Scallops ascended in the water column in straight, spiral, or twisting patterns, and the majority never swam horizontally. Two types of swimming were observed. Stable swimming, with a consistent body angle (the angle that the scallop makes with the horizon), was recorded over the size range of scallops examined. In stepwise swimming, the body angle alternated between steep (98 ± 13 (SD)) and more horizontal angles (51 ± 9°). Stepwise swimming was observed among the smaller (mean ± SD = 8 ± 3 mm) scallops. Maximum and mean velocities were positively correlated with both shell height and temperature. Clap rate (Cr) increased with increasing temperature (Cr = 0.29T (°C) + 1.3). Body angle expressed a significant relationship with shell height. Below 10 mm shell height the mean angle was 82°; between 30 and 35 mm the mean angle was 38°.

XX.—The Rate of Growth of Venerupis pullastra (Montagu) at Millport, Scotland

1952 ◽  
Vol 64 (4) ◽  
pp. 384-406 ◽  
Author(s):  
D. B. Quayle
Keyword(s):  
Annual Growth ◽  
Surface Sculpture ◽  
Rate Of Growth ◽  
Growth Increments ◽  
The Mean

SynopsisMarking experiments have demonstrated that certain of the rings appearing as surface sculpture on the shells of the lamellibranch Venerupis pullastra are valid as a measure of annual growth. From measurement of these rings the mean monthly and the mean annual growth increments have been calculated. The length-age relationship curve is similar to that of most other lamellibranchs. Reasons for the variation in the mean monthly rate of growth have been examined. The height-length and the thickness-length ratios for various sizes have been calculated and found to follow a simple and direct tangent relationship.

Biological and environmental rhythms reflected in molluscan shell growth

1968 ◽  
Vol 42 (S2) ◽  
pp. 64-80 ◽  
Author(s):  
Giorgio Pannella ◽  
Copeland Macclintock
Keyword(s):  
Shell Growth ◽  
Spring Tide ◽  
Growth Increment ◽  
Daily Growth ◽  
Mean Values ◽  
Daily Increments ◽  
Growth Increments ◽  
Tridacna Squamosa ◽  
The Mean ◽  
Daily Growth Increment

Tidal cycles are reflected in daily growth-increment sequences in shells of many Recent and fossil mollusks. Living specimens of the bivalve Mercenaria mercenaria were notched at the growing edge of the shell and planted intertidally in Barnstable Harbor, Massachusetts. Shells from two lots, killed at intervals of 368 and 723 days after planting, show the same number of small growth increments as there were days from notching to killing. Superimposed on daily growth record are effects of winter (thin daily increments) and tides (14-day cycles of thick and thin daily increments). Comparison of Barnstable tide record with the first year's growth shows that, for each 14-day cycle, thin daily increments form during neap tides and thicker daily increments form during spring tides. Although tidal patterns are present in subtidal Mercenaria shells, they are rarely as pronounced as in intertidal ones. Spawning patterns differ from winter patterns; they are expressed in the shell by an interruption of regular deposition followed by a series of thin daily increments. Continuous sequences of bidaily patterns, one thick daily increment followed by a relatively thin one, are common in M. mercenaria.The clearest 14-day cycles of deposition were seen in shells of the bivalve Tridacna squamosa. Each daily neap-tide increment is a simple layer consisting of a dark and light zone. Each daily spring-tide increment is a complex layer consisting of two light-dark alternations separated by a depositional break that is more pronounced than the breaks delimiting daily intervals. Preliminary results of growth-increment counts in fossils show a generally decreasing trend of the mean values of days per lunar month toward the Recent. The Pennsylvanian value is 30.07 ± 0.08, a figure that is in general agreement with those of Scrutton (1964), who counted 30.59 days per month on Devonian corals, and Barker (1966), who reported more than 30 days per month in Pennsylvanian bivalves.

Daily Growth Rates as Indicated by Valve Ridges in Postlarval Giant Scallop (Placopecten magellanicus) (Bivalvia: Pectinidae)

1993 ◽  
Vol 50 (3) ◽  
pp. 456-464 ◽  
Author(s):  
G. Jay Parsons ◽  
Shawn M. C. Robinson ◽  
John C. Roff ◽  
Michael J. Dadswell
Keyword(s):  
Growth Rates ◽  
Larval Fish ◽  
Shell Height ◽  
Age Determination ◽  
Growth Patterns ◽  
Placopecten Magellanicus ◽  
Short Term ◽  
Daily Growth ◽  
Alizarin Red ◽  
Growth Increments

Postlarval giant scallop (Placopecten magellanicus) were examined for daily growth ridges and growth rates by marking the dissoconch shell with Alizarin red dye. The surface of the left valve of postlarvae was composed of concentric ridges, each consisting of a series of irregularly shaped raised nodules. Ridges were clear and distinct in newly settled scallop between ≈0.25 and 2.0 mm shell height. The shell of postlarvae >2 mm was pigmented and ribbed and ridges were no longer distinguishable. Estimated age was significantly correlated with actual age, suggesting that growth ridges were produced daily, under the environmental conditions of Passamaquoddy Bay. Mean growth rate ranged from 32 to 57 μm∙d−1 and was proportional to size and age, but growth of individual scallop showed no coherence in their daily growth patterns. The short-term growth ridges in postlarval giant scallop can be used to determine age and can be applied to comparative growth, mortality, and recruitment studies of newly settled individuals <2.0 mm (≈40 d old postsettlement). The high accuracy and precision of age determination for postlarval scallop differs from studies of short-term internal growth increments of bivalve shells and larval fish otoliths.

scholarly journals Variability in the relationship between sea scallop shell height and meat weight

2009 ◽  
Vol 66 (9) ◽  
pp. 1972-1977 ◽  
Author(s):  
Brian J. Rothschild ◽  
Charles F. Adams ◽  
Christopher L. Sarro ◽  
Kevin D. E. Stokesbury
Keyword(s):  
Shell Height ◽  
Spatial And Temporal Variability ◽  
Commercial Fishing ◽  
Regression Equations ◽  
Placopecten Magellanicus ◽  
Scallop Shell ◽  
Linear Mixed Effects ◽  
Meat Weight ◽  
Sea Scallop ◽  
The Relationship

Abstract Rothschild, B. J., Adams, C. F., Sarro, C. L., and Stokesbury, K. D. E. 2009. Variability in the relationship between sea scallop shell height and meat weight. – ICES Journal of Marine Science, 66: 1972–1977. We investigated the spatial and temporal variability in the relationship between shell height and meat weight (SHMW) of the sea scallop (Placopecten magellanicus) from Georges Bank (GB) and the mid-Atlantic. Data for the study were collected collaboratively during normal commercial fishing operations. A one-way random-effects ANOVA revealed that 19–44% of the variance in MW was at the batch level. A linear mixed-effects model was used to explain the variability in SHMW regression equations across batches. There was a significant effect of month and year on the SHMW relationship for GB from June through December, and a significant effect of area and year on the SHMW relationship for the mid-Atlantic from January through May. The SHMW relationships presented reflect those of the fishery year-round rather than an estimate of the biological population at a specific point in time. Failure to include intra-annual, interannual, and regional variations in the SHMW could result in continually over- or underestimating the allowable catch in areas open to fishing for short periods. The techniques used are applicable to length–weight studies in general.

Planktonic Sea Scallop Larvae (Placopecten magellanicus) in the Georges Bank Region: Broadscale Distribution in Relation to Physical Oceanography

1992 ◽  
Vol 49 (8) ◽  
pp. 1597-1615 ◽  
Author(s):  
M. John Tremblay ◽  
Michael Sinclair
Keyword(s):  
Larval Abundance ◽  
Physical Oceanography ◽  
Georges Bank ◽  
Placopecten Magellanicus ◽  
Physical Processes ◽  
Scotian Shelf ◽  
Northern Flank ◽  
Sea Scallop ◽  
Scallop Larvae ◽  
The Mean

During autumn surveys for sea scallop larvae (Placopecten magellanicus) from 1985 to 1987, the mean abundance of sea scallop larvae on the northeast part of Georges Bank (1201–20080∙m−2) was much greater than on the southern Scotian Shelf (5–240∙m−2). Few larvae were collected between these two areas, and exchange between Georges Bank and the Scotian Shelf appears very limited. Transects across the northern flank in 1988 revealed peaks in larval abundance when on-bank temperature stratification was high. Relative larval abundance on the transects was positively related to the speed of the along-front current, suggesting physical convergence of larvae. The on-bank retention of scallop larvae on Georges Bank appears to be due to physical processes alone, since scallop larvae undertake only limited diel vertical migration. Larval exhange among adult scallop aggregations on Georges Bank (the northeast peak, the southeast part, and the South Channel) is probable, but evidence from this study is limited. The autumn production of late-stage larvae on the northern flank and northeast peak of Georges Bank is estimated to range from 120 to 1500∙m−2, which is 10–100 times greater than the density of scallops aged 1–2 yr.

Growth rate of the intermediate snail host Galba truncatula influences redial development of the trematode Fascioloides magna

2013 ◽  
Vol 88 (4) ◽  
pp. 427-433 ◽  
Author(s):  
D. Rondelaud ◽  
A. Novobilský ◽  
J. Höglund ◽  
M. Kašný ◽  
J. Pankrác ◽  
...  
Keyword(s):  
First Generation ◽  
Adult Stage ◽  
Shell Growth ◽  
Shell Height ◽  
Snail Host ◽  
Galba Truncatula ◽  
Fascioloides Magna ◽  
Group A ◽  
The Mean ◽  
Group D

AbstractA total of 850 pre-adult Galba truncatula (shell height, 4 mm), originating from four French snail populations differing in shell height at the adult stage (from 6.5 to 12 mm), were individually subjected at 20°C to single-miracidium infections with Fascioloides magna. At day 75 post-exposure, the surviving snails were dissected, and rediae and cercariae were counted. Snail groups differed in shell growth during the experiment: from 1.8 ± 0.4 mm in group A up to 4.0 ± 1.1 mm in group D. The prevalence of F. magna infection, the numbers of free rediae and cercariae significantly increased together with increasing growth of infected snails during the experiment. Group A produced 1–6 first-generation rediae per snail and the mean daughter redia production ranged from 7.5 second-generation rediae (when a single first generation per snail developed) to 2.3 (6 first-generation rediae per snail). In contrast, up to ten first-generation rediae were noted in group D, and each mother redia gave daughter rediae with averages ranging from 1.5 (ten first-generation rediae per snail) to 13 (a single first generation per snail). In conclusion, the development of F. magna in G. truncatula exhibited both inter- and intrapopulation variability, where the development of rediae and cercariae was positively correlated with snail growth.

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