Evaluating the potential for grey seal predation to explain elevated natural mortality in three fish species in the southern Gulf of St. Lawrence

Marine Ecology Progress Series

Volumn 442, Issue , 2011, Pages 149-167

  Benoǐt, Hugues P ^a   Swain, Douglas P ^a   Bowen, W Don ^b   Breed, Greg A ^c   Hammill, Mike O ^d   Harvey, Valerie ^d  

^a GULF FISHERIES CENTRE   (Canada)

^b BEDFORD INSTITUTE OF OCEANOGRAPHY   (Canada)

^c DALHOUSIE UNIVERSITY   (Canada)

^d MAURICE LAMONTAGNE INSTITUTE   (Canada)

Author keywords

Belly biting; Energetics model; Generalist predator; Monte Carlo simulation; Natural mortality; Partial consumption

Indexed keywords

DATA SET; DEMERSAL FISH; DEMOGRAPHY; DIET; FOOD CONSUMPTION; GADOID; GENERALIST; MONTE CARLO ANALYSIS; MORTALITY; NUMERICAL MODEL; PINNIPED; POPULATION STRUCTURE; PREDATION; PREY SELECTION; SPATIAL ANALYSIS; STOCK ASSESSMENT; UNCERTAINTY ANALYSIS;

ATLANTIC OCEAN; GULF OF SAINT LAWRENCE;

EID: 82955193265     PISSN: 01718630     EISSN: None     Source Type: Journal    
DOI: 10.3354/meps09454     Document Type: Article

References (106)

1. Austin D, Bowen WD, McMillan JI, Iverson SJ (2006) Linking movement, diving, and habitat to foraging success in a large marine predator. Ecology 87: 3095-3108 (Pubitemid 44969260)
2. Bax NJ (1998) The significance and prediction of predation in marine fisheries. ICES J Mar Sci 55: 997-1030 (Pubitemid 29042954)
3. Beck CA, Bowen WD, Iverson SJ (2003) Sex differences in the seasonal patterns of energy storage and expenditure in a phocid seal. J Anim Ecol 72: 280-291 (Pubitemid 36412988)
4. Beck CA, Iverson SJ, Bowen WD, Blanchard W (2007) Sex differences in grey seal diet reflect seasonal variation in foraging behaviour and reproductive expenditure: Evidence from quantitative fatty acid signature analysis. J Anim Ecol 76: 490-502 (Pubitemid 46606824)
5. Benoît HP (2006) Standardizing the southern Gulf of St. Lawrence bottom-trawl survey time series: Results of the 2004-2005 comparative fishing experiments and other recommendations for the analysis of the survey data. DFO Can Sci Advis Sec Res Doc 2006/008. Fisheries and Oceans Canada, Ottawa
6. Benoît HP, Swain DP (2008) Impacts of environmental change and direct and indirect harvesting effects on the dynamics of a marine fish community. Can J Fish Aquat Sci 65: 2088-2104
7. Benoît HP, Swain DP (2011) Changes in size-dependent mortality in the southern Gulf of St. Lawrence marine fish community. DFO Can Sci Advis Sec Res Doc 2011/ 039. Fisheries and Oceans Canada, Ottawa
8. Benoît HP, Swain DP, Hammill MO (2011) A risk analysis of the potential effects of selective and non-selective reductions in grey seal abundance on the population status of two species at risk of extirpation, white hake and winter skate in the southern Gulf of St. Lawrence. DFO Can Sci Advis Sec Res Doc 2011/033. Fisheries and Oceans Canada, Ottawa
9. Bolnick DI, Svanbäck R, Fordyce JA, Yang LH, Davis JM, Hulsey CD, Forister ML (2003) The ecology of individuals: Incidence and implications of individual specialization. Am Nat 161: 1-28 (Pubitemid 36144810)
10. Bousquet N, Cadigan N, Duchesne T, Rivest LP (2010) Detecting and correcting underreported catches in fish stock assessment: Trial of a new method. Can J Fish Aquat Sci 67: 1247-1261
11. Bowen WD (2000) Reconstruction of pinniped diets: Accounting for complete digestion of otoliths and cephalopod beaks. Can J Fish Aquat Sci 57: 898-905 (Pubitemid 30466316)
12. Bowen WD, Tully D, Boness DJ, Bulheier BM, Marshall GJ (2002) Prey-dependent foraging tactics and prey profitability in a marine mammal. Mar Ecol Prog Ser 244: 235-245 (Pubitemid 36035745)
13. Bowen WD, McMillan J, Mohn R (2003) Sustained exponential population growth of grey seals at Sable Island, Nova Scotia. ICES J Mar Sci 60: 1265-1274 (Pubitemid 37514848)
14. Bowen WD, McMillan JI, Blanchard W (2007) Reduced population growth of gray seals at Sable Island: Evidence from pup production and age of primiparity. Mar Mamm Sci 23: 48-64 (Pubitemid 46066554)
15. Bowen WD, Hammill MO, Koen-Alonso M, Stenson G, Swain DP, Trzcinski K (2009) Seal Impacts Workshop II. Can Sci Advis Sec Proc Ser 2009/020. Fisheries and Oceans Canada, Ottawa
16. Breed GA, Bowen WD, McMillan JI, Leonard ML (2006) Sexual segregation of seasonal foraging habitats in a non-migratory marine mammal. Proc R Soc B Biol Sci 273: 2319-2326 (Pubitemid 44387339)
17. Bundy A, Fanning LP (2005) Can Atlantic cod (Gadus morhua) recover? Exploring trophic explanations for the non-recovery of the cod stock on the eastern Scotian Shelf, Canada. Can J Fish Aquat Sci 62: 1474-1489 (Pubitemid 41483399)
18. Castellini MA, Kooyman GL, Ponganis PJ (1992) Metabolic rates of freely diving Weddell seals: Correlations with oxygen stores, swim velocity and diving duration. J Exp Biol 165: 181-194
19. Chassot E, Duplisea D, Hammill M, Caskenette A, Bousquet N, Lambert Y, Stenson G (2009) Role of predation by harp seals Pagophilus groenlandicus in the collapse and non-recovery of northern Gulf of St. Lawrence cod Gadus morhua. Mar Ecol Prog Ser 379: 279-297
20. Chouinard GA, Swain DP, Hammill MO, Poirier GA (2005) Covariation between grey seal (Halichoerus grypus) abundance and natural mortality of cod (Gadus morhua) in the southern Gulf of St. Lawrence. Can J Fish Aquat Sci 62: 1991-2000 (Pubitemid 41818825)
21. Clay D (1991) Seasonal distribution of demersal fish (Osteichthyes) and skates (Chondrichthyes) in the southeastern Gulf of St. Lawrence. In: Therriault J-C (ed) The Gulf of St Lawrence: Small ocean or big estuary? Can Spec Publ Fish Aquat Sci 113: 241-259
22. Comeau LA, Campana SE, Chouinard GA (2002) Timing of Atlantic cod (Gadus morhua L.) seasonal migrations in the southern Gulf of St. Lawrence: Interannual variability and proximate control. ICES J Mar Sci 59: 333-351 (Pubitemid 35235318)
23. Cook RM, Cockrell BJ (1978) Predator ingestion rate and its bearing on feeding time and the theory of optimal diets. J Anim Ecol 47: 529-547
24. Darbyson E, Benoît HP (2003) An atlas of the seasonal distribution of marine fish and invertebrates in the southern Gulf of St. Lawrence. Can Data Rep Fish Aquat Sci 1113. Fisheries and Oceans Canada, Ottawa
25. DFO (Fisheries and Oceans Canada) (2003) Proceedings of the zonal assessment meeting - Atlantic cod. DFO Can Sci Advis Sec Proc Ser 2003/021. Fisheries and Oceans Canada, Ottawa
26. DFO (Fisheries and Oceans Canada) (2009) Science advice on harvesting of northwest Atlantic harp seals (Pago - philus groenlandicus) in 2009. DFO Can Sci Advis Sec Sci Advis Rep 2008/058. Fisheries and Oceans Canada, Ottawa Dutil JD, Lambert Y (2000) Natural mortality from poor condition in Atlantic cod (Gadus morhua). Can J Fish Aquat Sci 57: 826-836 (Pubitemid 30334422)
27. Frank KT, Brickman D (2000) Allee effects and compensatory population dynamics within a stock complex. Can J Fish Aquat Sci 57: 513-517 (Pubitemid 30247448)
28. Fu C, Mohn R, Fanning LP (2001) Why the Atlantic cod (Gadus morhua) stock off eastern Nova Scotia has not recovered. Can J Fish Aquat Sci 58: 1613-1623 (Pubitemid 32752587)
29. Gende SM, Quinn TP, WillsonMF (2001) Consumption choice by bears feeding on salmon. Oecologia 127: 372-382 (Pubitemid 32449358)
30. Gildberg A (2004) Digestive enzyme activities in starved pre-slaughter farmed and wild-captured, Atlantic cod (Gadus morhua). Aquaculture 238: 343-353 (Pubitemid 39123655)
31. Goulet AM, Hammil MO, Barette C (2001) Movements and diving of grey seal females (Halichoerus grypus) in the Gulf of St. Lawrence, Canada. Polar Biol 24: 432-439
32. Grahl-Nielsen O, Haug T, Lindstrøm U, Nilssen KT (2011) Fatty acids in harp seal blubber do not necessarily reflect their diet. Mar Ecol Prog Ser 426: 263-276
33. Grellier K, Hammond PS (2006) Robust digestion and passage rate estimates for hard parts of grey seal (Halicho - erus grypus) prey. Can J Fish Aquat Sci 63: 1982-1998 (Pubitemid 44757134)
34. Gudmundson CJ, Zeppelin TK, Ream RR (2006) Application of two methods for determining diet of northern fur seals (Callorhinus ursinus). Fish Bull 104: 445-455 (Pubitemid 43955661)
35. Hammill MO (2005) Abundance of Northwest Atlantic grey seals in the Gulf of St. Lawrence and along the Nova Scotia Eastern Shore. Can Sci Advis Sec Res Doc 2005/036. Fisheries and Oceans Canada, Ottawa
36. Hammill MO, Stenson GB (2000) Estimated prey consumption by harp seals (Phoca groenlandica), hooded seals (Cystophora cristata), grey seals (Halichoerus grypus) and harbour seals (Phoca vitulina) in Atlantic Canada. J Northwest Atl Fish Sci 26: 1-23
37. Hammill MO, Stenson GB, Myers RA, Stobo WT (1998) Pup production and population trends of the grey seal (Halichoerus grypus) in the Gulf of St. Lawrence. Can J Fish Aquat Sci 55: 423-430 (Pubitemid 28290517)
38. Hammill MO, Stenson GB, Proust F, Carter P, McKinnon D (2007) Feeding by grey seals in the Gulf of St. Lawrence and around Newfoundland.NAMMCOSci Publ 6: 135-152
39. Harley SJ, Myers RA (2001) Hierarchical Bayesian models of length-specific catchability of research trawl surveys. Can J Fish Aquat Sci 58: 1569-1584 (Pubitemid 32752583)
40. Harvey V, Côté SD, Hammil MO (2008) The ecology of 3-D space use in a sexually dimorphic mammal. Ecography 31: 371-380 (Pubitemid 351799693)
41. Hauser DDW, Allen CS, Rich HBJ, Quinn TP (2008) Resident harbor seals (Phoca vitulina) in Iliamna Lake, Alaska: Summer diet and partial consumption of adult sockeye salmon (Oncorhynchus nerka). Aquat Mamm 34: 303-309
42. Hurlbut T, Clay D (1990) Protocols for research vessel cruises within the Gulf Region (demersal fish) (1970- 1987). Can Ms Rep Fish Aquat Sci 2082. Fisheries and Oceans Canada, Ottawa
43. Hurlbut T, Morin R, Surette T, Swain DP, Benoît HP, LeBlanc C (2010) Preliminary results from the September 2009 bottom-trawl survey of the southern Gulf of St. Law - rence. Can Sci Advis Sec Res Doc 2010/044. Fisheries and Oceans Canada, Ottawa
44. Hutchings JA (2005) Life history consequences of overexploitation to population recovery in Northwest Atlantic cod (Gadus morhua). Can J Fish Aquat Sci 62: 824-832 (Pubitemid 40962754)
45. Hutchings JA, Baum JK (2005) Measuring marine fish biodiversity: Temporal changes in abundance, life history and demography. Philos Trans R Soc B 360: 315-338 (Pubitemid 41529628)
46. Ingenbleek Y (2006) The nutritional relationship linking sulfur to nitrogen in living organisms. J Nutr 136(Suppl): 1641S-1651S (Pubitemid 43765375)
47. Innes S, Lavigne DM, Earle WM, Kovacs KM(1987) Feeding rates of seals and whales. J Anim Ecol 56: 115-130
48. Iverson SJ (2009) Tracing aquatic food webs using fatty acids: From qualitative indicators to quantitative determination. In: Arts MT, Brett MT, Kainz MJ (eds) Lipids in aquatic ecosystems. Springer Science, New York, NY, p 281-307
49. Iverson SJ, Field C, Bowen D, Blanchard W (2004) Quantitative fatty acid signature analysis: A new method of estimating predator diets. Ecol Monogr 74: 211-235 (Pubitemid 39182893)
50. Jonsen ID, Mills-Flemming J, Myers RA (2005) Robust statespace modeling of animal movement data. Ecology 86: 2874-2880 (Pubitemid 41677441)
51. Kleiber M (1975) The fire of life: An introduction to animal energetics. Robert E. Krieger Publishing, New York, NY
52. Koen-Alonso M (2007) A process-oriented approach to the multispecies functional response. In: Rooney N, McCann KS, Noakes DLG (eds) From energetics to ecosystems: The dynamics and structure of ecological systems. Springer, Dordrecht, p 1-36
53. Koen-Alonso M, Yodzis P (2005) Multispecies modelling of some components of the marine community of northern and central Patagonia, Argentina. Can J Fish Aquat Sci 62: 1490-1512 (Pubitemid 41483400)
54. Lavigne DM, Innes S, Worthy GAJ, Kovacs KM (1986) Metabolic rate-body size relations in marine mammals. J Theor Biol 122: 123-124
55. Lavigueur L, Hammill MO (1993) Distribution and seasonal movements of grey seals, Halichoerus grypus, born in the Gulf of St. Lawrence and eastern Nova Scotia shore. Can Field Nat 107: 329-340 (Pubitemid 2102718)
56. Lawson JW, Magalhaes AM, Miller EH (1998) Important prey species of marine vertebrate predators in the northwest Atlantic: Proximate composition and energy density. Mar Ecol Prog Ser 164: 13-20 (Pubitemid 28213856)
57. Lilly GR, Murphy EF (2004) Biology, fishery and status of the 2GH and 2J3KL (northern) cod stocks: Information supporting an assessment of allowable harm under the Species at Risk Act for the COSEWIC-defined Newfoundland and Labrador population of Atlantic cod (Gadus morhua). Can Sci Advis Sec Res Doc 2004/102. Fisheries and Oceans Canada, Ottawa
58. Mackinson S, Blanchard JL, Pinnegar JK, Scott R (2003) Consequences of alternative functional response formulations in models exploring whale-fishery interactions. Mar Mamm Sci 19: 661-681 (Pubitemid 37274105)
59. Macpherson E, Duarte CM (1991) Bathymetric trends in demersal fish size: Is there a general relationship? Mar Ecol Prog Ser 71: 103-112
60. Marshall GJ (1998) Crittercam: An animal borne imaging and data logging system. Mar Technol Soc J 32: 11-17 (Pubitemid 28416019)
61. Matthiopoulos J, Smout S, Winship AJ, Thompson D, Boyd IL, Harwood J (2008) Getting beneath the surface of marine mammal-fisheries competition. Mammal Rev 38: 167-188 (Pubitemid 351566637)
62. Mohn R, Bowen WD (1996) Grey seal predation on the eastern Scotian Shelf: Modelling the impact on Atlantic cod. Can J Fish Aquat Sci 53: 2722-2738 (Pubitemid 27259094)
63. Moore PG (2003) Seals and fisheries in the Clyde Sea area (Scotland): Traditional knowledge informs science. Fish Res 63: 51-61 (Pubitemid 36725810)
64. Murie DJ, Lavigne DM (1985) Digestion and retention of Atlantic herring otoliths in the stomachs of grey seals. In: Beddington JR, Beverton RJH, Lavigne DM (eds) Marine mammals and fisheries. George Allen and Unwin Publishing, London, p 292-299
65. Myers RA, Bowen KG, Barrowman NJ (1999) Maximum reproductive rate of fish at low population sizes. Can J Fish Aquat Sci 56: 2404-2419 (Pubitemid 30112603)
66. Nordstrom CA, Wilson LJ, Iverson SJ, Tollit DJ (2008) Evaluating quantitative fatty acid signature analysis (QFASA) using harbour seals Phoca vitulina richardsi in captive feeding studies. Mar Ecol Prog Ser 360: 245-263 (Pubitemid 351960152)
67. Olesiuk PF (1993) Annual prey consumption by harbor seals (Phoca vitulina) in the Strait of Georgia, British Columbia. Fish Bull 91: 491-515 (Pubitemid 24417230)
68. Overholtz WJ, Link JS (2007) Consumption impacts by ma - rine mammals, fish, and seabirds on the Gulf of Maine- Georges Bank Atlantic herring (Clupea harengus) complex during the years 1977-2002. ICES J Mar Sci 64: 83-96 (Pubitemid 47083237)
69. Penry DL (1993) Digestive constraints on diet selection. In: Hughes RN (ed) Diet selection. Blackwell, Cambridge, MA, p 32-55
70. Phillips EM, Harvey JT (2009) A captive feeding study with the Pacific harbor seal (Phoca vitulina richardii): Implications for scat analysis. Mar Mamm Sci 25: 373-391
71. Punt AE, Butterworth DS (1995) The effects of future consumption by the cape fur seal on catches and catch rates of the cape hakes. 4. Modelling the biological interaction between cape fur seals Arctocephalus pusillus pusillus and the cape hakes Merluccius capensis and M. paradoxus. S Afr J Mar Sci 16: 255-285
72. Rochet MJ (1998) Short-term effects of fishing on life history traits of fishes. ICES J Mar Sci 55: 371-391
73. Roffe TJ, Mate BR (1984) Abundance and feeding habits of pinnipeds in the Rogue River, Oregon. J Wildl Manage 48: 1262-1274 (Pubitemid 16278189)
74. Ronald K, Keiver KM, Beamish FWH, Frank R (1984) Energy requirements for maintenance and faecal and urinary losses of the grey seal (Halichoerus grypus). Can J Zool 62: 1101-1105 (Pubitemid 16271691)
75. Saltelli A, Tarantola S, Campolongo F (2000) Sensitivity ana - lysis as an ingredient of modeling. Stat Sci 15: 377-395
76. Savenkoff C, Swain DP, Hanson JM, CastonguayMand others (2007) Effects of fishing and predation in a heavily exploited ecosystem: Comparing periods before and after the collapse of groundfish in the southern Gulf of St. Lawrence (Canada). Ecol Modell 204: 115-128 (Pubitemid 46602679)
77. Savenkoff C, Morissette L, Castonguay M, Swain DP, Hammill MO, Chabot D, Hanson JM (2008) Interactions between marine mammals and fisheries: Implications for cod recovery. In: Chen J, Guo C (eds) Ecosystem ecology research trends. Nova Science Publishers, New York, NY, p 107-151
78. Savoie L, Surette T (2010) Results from the August 2008 sentinel bottom trawl survey of the southern Gulf of St. Lawrence. DFO Can Sci Advis Sec Res Doc 2010/033. Fisheries and Oceans Canada, Ottawa
79. Schwalme K, Chouinard GA (1999) Seasonal dynamics in feeding, organ weights, and reproductive maturation of Atlantic cod (Gadus morhua) in the southern Gulf of St Lawrence. ICES J Mar Sci 56: 303-319 (Pubitemid 29351157)
80. Shelton PA, Sinclair AF, Chouinard GA, Mohn R, Duplisea DE (2006) Fishing under low productivity conditions is further delaying recovery of Northwest Atlantic cod (Gadus morhua). Can J Fish Aquat Sci 63: 235-238
81. Sih A (1980) Optimal foraging: Partial consumption of prey. Am Nat 116: 281-290
82. Sinclair AF (2001) Natural mortality of cod (Gadus morhua) in the Southern Gulf of St. Lawrence. ICES J Mar Sci 58: 1-10 (Pubitemid 32453898)
83. Smout S, Lindstrøm U (2007) Multispecies functional response of the minke whale Balaenoptera acutorostrata based on small-scale foraging studies. Mar Ecol Prog Ser 341: 277-291 (Pubitemid 47195077)
84. Sparling CE, Fedak MA (2004) Metabolic rates of captive grey seals during voluntary diving. J Exp Biol 207: 1615-1624 (Pubitemid 38630491)
85. Steimle FW Jr, Terranova RJ (1985) Energy equivalents of marine organisms from the continental shelf of the temperate northwest Atlantic. J Northwest Atl Fish Sci 6: 117-124
86. Stobo WT, Beck B, Horne JK (1990) Seasonal movements of grey seals (Halichoerus grypus) in the Northwest Atlantic. In: Bowen WD (ed) Population biology of sealworm (Pseudoterranova decipiens) in relation to its intermediate and seal hosts. Can Bull Fish Aquat Sci 222: 199-213
87. Swain DP (1993) Age- and density-dependent bathymetric pattern of Atlantic cod (Gadus morhua) in the southern Gulf of St. Lawrence. Can J Fish Aquat Sci 50: 1255-1264 (Pubitemid 24408382)
88. Swain DP (2011) Life-history evolution and elevated natural mortality in a population of Atlantic cod (Gadus morhua). Evol Appl 4: 18-29
89. Swain DP, Chouinard GA (2008) Predicted extirpation of the dominant demersal fish in a large marine ecosystem: Atlantic cod (Gadus morhua) in the southern Gulf of St. Lawrence. Can J Fish Aquat Sci 65: 2315-2319
90. Swain DP, Sinclair AF (1994) Fish distribution and catchability: What is the appropriate measure of distribution? Can J Fish Aquat Sci 51: 1046-1054 (Pubitemid 2119354)
91. Swain DP, Sinclair A (2000) Pelagic fishes and the cod recruitment dilemma in the Northwest Atlantic. Can J Fish Aquat Sci 57: 1321-1325
92. Swain DP, Sinclair AF, Chouinard GA, Drinkwater KF (2000) Ecosystem effects on pre-recruit survival of cod in the southern Gulf of St. Lawrence. DFO Can Sci Advis Sec Res Doc 2000/147. Fisheries and Oceans Canada, Ottawa
93. Swain, DP, Simon JE, Harris LE, Benoît HP (2006) Recovery potential assessment of 4T and 4VW winter skate (Leucoraja ocellata): Biology, current status and threats. Can Sci Advis Sec Res Doc 2006/003. Fisheries and Oceans Canada, Ottawa
94. Swain DP, Jonsen ID, Simon JE, Myers RA (2009a) A stagestructured state-space model to assess threats and management scenarios for data-deficient species-at-risk: Estimating mortality trends in winter skate (Leucoraja ocellata, Family Rajidae). Ecol Appl 19: 1347-1364
95. Swain, DP, Savoie L, Hurlbut T, Surette T, Daigle D (2009b) Assessment of the southern Gulf of St. Lawrence cod stock, February 2009. DFO Can Sci Advis Sec Res Doc 2009/037. Fisheries and Oceans Canada, Ottawa
96. Swain, DP, Benoît HP, Hammill MO, McClelland G, Aubrey É (2011) Alternative hypotheses for causes of the elevated natural mortality of southern Gulf cod: The weight of evidence. DFO Can Sci Adv Sec Res Doc 2011/036. Fisheries and Oceans Canada, Ottawa
97. Trzcinski MK, Mohn R, Bowen WD (2006) Continued decline of an Atlantic cod population: How important is gray seal predation? Ecol Appl 16: 2276-2292 (Pubitemid 44917586)
98. 15N). Mar Ecol Prog Ser 339: 271-282 (Pubitemid 47025336)
99. Walters C, Kitchell JF (2001) Cultivation/depensation effects on juvenile survival and recruitment: Implications for the theory of fishing. Can J Fish Aquat Sci 58: 39-50 (Pubitemid 32185261)
100. Williams TM, Estes JA, Doak DF, Springer AM (2004) Killer appetites: Assessing the role of predators in ecological communities. Ecology 85: 3373-3384 (Pubitemid 40084785)
101. Wirsing AJ, Dill LM, Frid A (2008) Seascapes of fear: Evaluating sublethal predator effects experienced and generated by marine mammals. Mar Mamm Sci 24: 1-15 (Pubitemid 351239272)
102. Worthy GAJ (1987a) Ecological energetics of harp and grey seals: Implications from a simulation model. In: Huntley AC, Cost DP, Worthy GAJ, Castellini MA (eds) Marine mammal energetics. Allen Press, Lawrence, KS, p 227-246
103. Worthy GAJ (1987b) Metabolism and growth of young harp and grey seals. Can J Zool 65: 1377-1382
104. Worthy GAJ (1990) Nutritional energetics in marine mammals: Addendums. In: Dierauf LA (ed) CRC handbook of marine mammal medicine: Health, disease and rehabilitation. CRC Press, Boca Raton, FL, p 489-520
105. Yodzis P (1998) Local trophodynamics and the interaction of marine mammals and fisheries in the Benguela ecosystem. J Anim Ecol 67: 635-658 (Pubitemid 28351553)
106. Yodzis P (2001) Must top predators be culled for the sake of fisheries? Trends Ecol Evol 16: 78-84 (Pubitemid 32140409)