Ecological Archives A016-073-A1

M. Kurtis Trzcinski, Robert Mohn, and W. Don Bowen. 2006. Continued decline of an Atlantic cod population: How important is gray seal predation? Ecological Applications 16:2276–2292.

Appendix A. Values used in simulation model. Two distributions were used: N = normal, B = binomial. YOY = young of the year. ESS = Eastern Scotian Shelf.

Parameter

Symbol

Group

Mean

Distribution

SD

Reference

             

Birth rate

b

age

       
   

4

0.15

B

0.0442

Zwanenburg and Bowen 1990

           

Hammill and Gosselin 1995

   

5

0.70

B

0.0618

Zwanenburg and Bowen 1990

           

Hammill and Gosselin 1995

   

6

0.85

B

0.0457

Zwanenburg and Bowen 1990

           

Hammill and Gosselin 1995

   

7

0.83

B

0.0446

Zwanenburg and Bowen 1990

           

Hammill and Gosselin 1995

   

8

0.96

B

0.0418

Zwanenburg and Bowen 1990

           

Hammill and Gosselin 1995

   

9

0.96

B

0.0400

Zwanenburg and Bowen 1990

           

Hammill and Gosselin 1995

   

10+

0.90

B

0.0202

Zwanenburg and Bowen 1990

           

Hammill and Gosselin 1995

             

Density dependence

θ

pups, juveniles

2.4

.

CONSTANT

Taylor and DeMaster 1993, Harting 2002

             

Proportion on ESS

           

Sable Island population

m

quarter

       
   

male

       
   

1

0.66

B

0.0684

Austin et al. 2004

   

2

0.81

B

0.0566

Breed and Bowen unpublished data

   

3

0.64

B

0.0693

Austin et al. 2004

   

4

0.75

B

0.0625

Breed and Bowen unpublished data

   

female

       
   

1

0.87

B

0.0476

Austin et al. 2004

   

2

0.76

B

0.0604

Breed and Bowen unpublished data

   

3

0.60

B

0.0693

Austin et al. 2004

   

4

0.74

B

0.0620

Breed and Bowen unpublished data

   

YOY

       
   

1

0.92

B

0.0566

Austin et al. 2004

   

2

0.97

B

0.0356

Breed and Bowen unpublished data

   

3

0.83

B

0.0783

Austin et al. 2004

   

4

0.93

B

0.0532

Breed and Bowen unpublished data

Gulf population

 

all

       
   

1

0.39

B

0.0670

Hammill unpublished data

   

2

0.29

B

0.0623

Hammill unpublished data

   

3

0.01

B

0.0412

Hammill unpublished data

   

4

0.08

B

0.0549

Hammill unpublished data

             

Kleiber multiplier

 

1+

1.7

N

0.55125

Sparling and Fedak 2004

   

pups

2.5

.

CONSTANT

Worthy 1987

   

females

       
   

[summer]

1.075

.

CONSTANT

Boily and Lavinge 1995, Beck et al. 2003

             

Annual growth

GR

male

       

(Gompertz parameters)

 

p 1

52.0

N

285.8

Mohn and Bowen 1996

   

p 2

1.6

N

5.17

Mohn and Bowen 1996

   

p 3

0.2

N

1.45

Mohn and Bowen 1996

   

female

       
   

p 1

47.8

N

210.3

Mohn and Bowen 1996

   

p 2

1.3

N

4.17

Mohn and Bowen 1996

   

p 3

0.2

N

1.23

Mohn and Bowen 1996

             

Body mass (kg)

BM

male

       

(seasonal)

 

i = 1

241

N

34.8

Beck et al. 2003

   

i = 2

240

N

24.8

Beck et al. 2003

   

i = 3

199

N

37.6

Beck et al. 2003

   

i = 4

291

N

28.8

Beck et al. 2003

   

female

       
   

i = 1

144

N

15.6

Beck et al. 2003

   

i = 2

160

N

17.8

Beck et al. 2003

   

i = 3

133

N

22.9

Beck et al. 2003

   

i = 4

153

N

13.9

Beck et al. 2003

   

i = 5

207

N

32.9

Beck et al. 2003

   

pup at weaning

54.0

N

5.69

Boness et al. 1995

   

pup at 5 months

36.8

N

4.37

Cooper 2004

             

Total body energy (MJ)

TBE

male

       

(seasonal)

 

i = 1

3180

N

742.3

Beck et al. 2003

   

i = 2

2956

N

486.8

Beck et al. 2003

   

i = 3

2014

N

760.3

Beck et al. 2003

   

i = 4

3292

N

944.7

Beck et al. 2003

   

i = 5

4460

N

923.8

Beck et al. 2003

   

female

       
   

i = 1

1729

N

446.1

Beck et al. 2003

   

i = 2

2205

N

428.4

Beck et al. 2003

   

i = 3

1534

N

553.4

Beck et al. 2003

   

i = 4

2030

N

384.2

Beck et al. 2003

   

i = 5

3504

N

724.2

Beck et al. 2003

             

Energy density of growth

TBE

juvenile

11.38

N

2.78

Bowen et al. 1999

(MJ/kg)

           
             

Metabolizable energy

ME

 

0.83

N

0.0482

Ronald et al. 1984

             

Average energy density

AE

quarter

       

(kJ/g)

 

1, 2

5.281

N

0.659

Beck et al. submitted

   

3

5.256

N

0.297

Beck et al. submitted

   

4

5.465

N

0.349

Beck et al. submitted

   

YOY

5.345

N

0.483

Beck et al. submitted

             

Proportion cod in diet

f

quarter

       
   

male

       
   

1, 2

0.0040

N

0.0842

Beck et al. submitted

   

3

0.0000

N

0.0063

Beck et al. submitted

   

4

0.0100

N

0.0591

Beck et al. submitted

   

female

       
   

1, 2

0.0040

N

0.0333

Beck et al. submitted

   

3

0.0450

N

0.1635

Beck et al. submitted

   

4

0.0150

N

0.0716

Beck et al. submitted

   

YOY

0.0858

N

0.1839

Beck et al. submitted

             

Proportion cod at age in diet

p

age

       
   

1

0.3410

B

0.0463

This study

   

2

0.3437

B

0.0475

 
   

3

0.2173

B

0.0500

 
   

4

0.0759

B

0.0530

 
   

5

0.0185

B

0.0603

 
   

6

0.0030

.

CONSTANT

 
   

7

0.0004

.

CONSTANT

 
   

8

0.0001

.

CONSTANT

 
             

LITERATURE CITED

Austin, D., W. D. Bowen, and J. I. McMillan. 2004. Intraspecific variation in movement patterns: modeling individual behaviour in a large marine predator. Oikos105:15–30.

Beck, C. A., W. D. Bowen, and S. J. Iverson. 2003a. Seasonal energy storage and expenditure in a phocid seal: evidence of sex-specific trade-offs. Journal of Animal Ecology 72:280–291.

Boily , P., and D. M. Lavigne. 1995. Resting metabolic rates and respiratory quotients of grey seals ( Halichoerus grypus) in relation to time of day and duration of food deprivation. Physiological Zoology 68:1181–1193.

Boness , D. J., W. D. Bowen, and S. J. Iverson. 1995. Does male harassment of females contribute to reproductive synchrony in the grey seal by affecting maternal performance? Behavior, Ecology and Sociobiology 36:1–10.

Bowen, W. D., D. J. Boness, and S. J. Iverson. 1999. Diving behaviour of lactating harbour seals and their pups during maternal foraging trips. Canadian Journal of Zoology 77:978–988.

Cooper, M. H. 2004. Fatty acid metabolism in marine carnivores: implications for quantitative estimation of predator diets. PhD Thesis. Dalhousie University, Halifax, Nova Scotia.

Hammill , M. O., and J. F. Gosselin. 1995. Grey seal ( Halichoerus grypus) from the Northwest Atlantic: female reproductive rates, age at first birth, and age of maturity of males. Canadian Journal of Fisheries and Aquatic Sciences 52:2757–2761.

Harting, A. L. 2002. Stochastic simulations model for the Hawaiian monk seal. PhD Thesis. Montana State University, Bozeman, Montana, USA.

Mohn , R., and W. D. Bowen. 1996. Grey seal predation on the eastern Scotian Shelf: modelling the impact on Atlantic cod. Canadian Journal of Fisheries and Aquatic Science 53:2722–2738.

Ronald, K., K. M. Keiver, F. W. H. Beamish, and R. Frank. 1984. Energy requirements for maintenance and faecal and urinary losses of the grey seal ( Halichoerus grypus). Canadian Journal of Zoology 62:1101–1105.

Sparling , C. E., and M. A. Fedak. 2004. Metabolic rates of captive grey seals during voluntary diving. Journal of Experimental Biology 207:1615–1624.

Taylor, B. L., and D. P. DeMaster. 1993. Implications of non-linear density dependence. Marine Mammal Science 9:360–371.

Worthy, G. A. J. 1987. Metabolism and growth of young harp and grey seals. Canadian Journal of Zoology 65:1377–1382.

Zwanenburg , K. C. T., and W. D. Bowen. 1990. Population trends of the grey seal ( Halichoerus grypus) in eastern Canada. Pages 185–197 in W. D. Bowen, editor. Population biology of sealworm ( Pseudoterranova decipiens) in relation to its intermediate and seal hosts. Canadian Bulletin of Fisheries and Aquatic Sciences, No. 222, Ottawa.



[Back to A016-073]