Update on scallop meat

quality from RSA research

CFF: Liese Siemann, Luisa Garcia, Samir Patel, and Ron Smolowitz

UM: Carl Huntsberger

RWU: Roxanna Smolowitz and Ava Mastrostefano

NOAA: Heather Haas

MAAS: Bob Prescott and Karen Dourdeville

• Goal is to examine the impact of biotic and abiotic factors on gray meat

prevalence and the likelihood of individual scallops having gray meats

• Five survey trips between August 2013 and March 2014 on the southern

portion of Georges Bank and fifteen survey trips between August 2015

and June 2017 on the northern portion of Georges Bank

• Meat quality was assessed based on a qualitative color scale with three

categories with colors ranging from white to brown to gray

• A subset of the collected meats were evaluated for the presence of

apicomplexan parasites at the Aquatic Diagnostic Laboratory at Roger

Williams University

Gray meat modeling

Total numbers of scallops assessed during each

survey month.Survey month and year Number of scallops sampled

September 2013 396

October 2013 380

December 2013 364

January 2014 363

March 2014 399

August 2015 411

September 2015 558

October 2015 557

November 2015 605

January 2016 563

March 2016 654

May 2016 641

June 2016 527

July 2016 530

October 2016 517

November 2016 385

January 2017 483

March 2017 520

May 2017 628

June 2017 502

9,983 scallops sampled

4.92% had gray or brown meats

Scallop relative abundance

• Gray meat prevalence at each station for each survey trip was modeled

using a quasibinomial distribution

• Meat quality of individual scallops, as gray meat presence (gray or brown)

or absence (white), was modeled using a binomial distribution

• Southern and northern stations were modeled separately due to the survey

area shift between 2014 and 2015

• Fixed effects used for modeling

• location (“easting” and “northing” in UTM space)

• bottom depth (29 – 106 m)

• bottom temperature (4 - 19°C)

• scallop density (0.38 - 640 bushels/km2)

• clapper ratio as proxy for natural mortality (0 - 2.0)

• scallop reproductive stage

• shell height

• area (Closed Area I, Closed Area II, open)

• downstream distance from a closed area (in a closed area, < 5 km from

a closed area, between 5 and 10 km from a closed area, or >10 km from

a closed area)

Selected models

Significant effects included

• location

• average shell height

• clapper ratio

• area (high in Closed Area I)

Southern Georges Bank 2013-2014

Northern Georges Bank 2015-2017

Significant effects included

• location

• bottom depth

• percentage of spent scallops

Significant effects included

• location

• shell height

• clapper ratio

• area (high in Closed Area I)

• scallop density

Gray meat prevalence Meat color/quality

Significant effects included

• scallop density

• shell height

• reproductive stage

Southern vs northern Georges Bank

Gray meats were more common when

• scallops were large (older)

• in areas with high natural mortality

• in a localized area (Closed Area I)

Northern Georges Bank

2015-2017

Southern Georges Bank

2013-2014

Gray meats were more common when

• scallops were spent

Suggests different causes for gray meats observed in these areas (and

years) – disease vs stress/energy depletion following spawning?

Relationship between meat color and severity of infection (assessed

using histological techniques) and presence of parasite (assessed using

PCR) is unclear

Apicomplexan parasite in discolored

meats from northern Georges Bank

Meat colorProtozoan

numberPCR +/-

White 0 Negative

Tan 0 Positive *

Tan 6 Negative *

Tan 9 Negative *

Brown 22 Positive

Brown 28 Positive

Brown 35 Positive

Gray 0 Positive *

Gray 3 Negative *

Gray 13 Positive

Gray 13 Positive

Gray 15 Positive

* Protozoan number vs PCR

detection of parasite don’t agree

Most recent data on gray meats on

Georges Bank (2017-2018)

Year Month Scallop

sampled Brown meat

Gray meat

Orange nodules

2017

August 873 5 2 1

September 782 3 1 0

October 777 13 2 2

December 754 7 4 1

2018

January 755 8 1 0

February 841 4 1 2

April 745 15 1 0

June 864 4 0 0

December had more gray

meats, and October and

April more brown meats

Orange nodules - mycobacteriumYear Month Scallops sampled

Orange Pustules

2013

September 396 8

October 380 5

December 364 4

2014 January 363 4

March 399 5

2015

August 411 4

September 558 0

October 557 4

November 605 5

2016

January 563 3

March 654 5

May 641 3

June 527 1

July 530 0

October 517 0

November 385 0

2017

January 483 0

March 520 0

May 628 0

June 502 1

Orange pustules (2013-2017)

Found in scallops from

stations where gray meats

were also prevalent

Grimm C, Huntsberger C, Markey K,

Inglis S, and Smolowitz R. 2016.

Identification of a Mycobacterium sp. as

the causative agent of orange nodular

lesions in the Atlantic sea scallop

Plactopecten magellanicus. Diseases of

Aquatic Organisms 118: 247 – 258

2016 2017 2018

Nematodes and TurtlesSince 2016, CFF has been taking

lavage samples from live turtles, and

gut content/fecal samples from dead

turtles that strand on Cape Cod. 16%

of all turtles have been positive for

nematodes.

Tagged Dead Tagged Dead

2016 22 28 6 1

2017 22 10 5 1

2018 35 33 7 4

Total 79 71 18 6

CCL mean ± SD (cm) 79.9 ± 9.6 81.4 ± 9.3

Total Turtles Positive NematodeYear

Turtles +Nematode

Microplastic?

S. sulcata egg

Nematodes and Turtles