Chlorinated Organic Contaminants in Blubber Biopsies from Northwestern Atlantic Balaenopterid Whales Summering in the Gulf of St Lawrence

Home , Beluga whale, Minke whale, Narwhal

J. M. Gauthier,a* C. D. Metcalfe” & R. Sear@

“Environmental and Resources Studies, Trent University, Peterborough, Ontario, Canada K9J 7B8 bMingan Island Cetacean Study (MICS), 285 Green, St. Lambert, Quebec, Canada J4P IT3

(Received 16 May 1996; revised version received 16 December 1996; accepted 29 December 1996. Published June 1997)

ABSTRACT

Concentrations and patterns of chlorinated biphenyls (CBS) and other persistent organochlorine compounds (OCs) were determined from small blubber biopsy samples collected from northwestern Atlantic minke (Balaenoptera acurostrata) , fin (Balaenoptera physalus), blue (Balaenoptera musculus) , and humpback (Megaptera novaeangliae) whales summering in the Gurf of St. Lawrence, Quebec. Concentrations of CPCB (sum of 19 congeners) in biopsy samples ranged from 0.2-10 pg g-’ lipid, and congeners 52, 101, 118, 153, 138 and 180 accounted for 79% of CPCB. Mean concentration of the sum of non- ortho CB congeners in selected biopsy samples was 2 ng g-t lipid, and relative concentrations of these analytes were: 77 > 126 > 81> 169. Concentrations of XDDT ranged from 0.613 pg g-t lipid, and the average proportion of DDE to CDDT was 72%. All other organochlorine analytes were present at concentrations below 2 pg g-t lipid. On average, cis-nonachlor, trans-nonachlor and oxychlordane accounted for 27, 26 and 23%, respectively, of the chlordane-related analytes, and cl-hexachlorocyclohexane (HCH) comprised 67% of XHCH. Concentrations of CDDT were signtficantly lower and mirex concentrations were significantly higher in minke whales than in the other balaenopterid species. Concentrations of all other analytes were similar in the four whale species. Ratios of proportions of oxychlordane to trans-nonachlor were highest in fin whales. Blue whales had the lowest proportions of u-HCH but the highest proportions of DDT. Interspecies diflerences in the concentrations and patterns of certain CB

*To whom correspondence should be addressed at Departement de Sciences Biologiques, Universite du Quebec a Montreal, C. P. 8888, Succ. Centre-Ville, Montreal, Quebec, H3C 3P8, Canada. E-mail: C2656Ber.ugam.ca

201 202 J. M. Gauthier et al.

congeners and OC compounds may reject d@erences in diet or in metabolic capabilities. Males usually had higher mean concentrations of CBS and OCs than females, but these differences were sign$cant only for CDDT, dieldrin, CHCH and HCB. Higher proportions of lower chlorinated CB congeners were found in calves compared to adult females, indicating selective reproductive transfer. 0 1997 Elsevier Science Ltd

INTRODUCTION

Polychlorinated biphenyls (PCB) and other organochlorine (OC) compounds are persistent, lipophilic compounds that accumulate in the fatty tissues of biota. Whales have a lipid- rich blubber mantle that comprises most of the lipid storage tissue of the animal (Lockyer et al., 1985). The blubber layers of these animals accumulate lipophilic contaminants in utero and during post-utero development, and throughout their life-span. Most monitoring studies of PCB and OC contaminants in whales have been done with odontocetes. However, ppb and ppm concentrations of these persistent contaminants have been detected in baleen whale blubber (Colborn & Smolen, 1996; Marsili & Focardi, 1996). Contaminant data for northwestern Atlantic balaenopterid whales in the St. Lawrence region are limited (BCland et al., 1992; Gauthier et al., 1997). Balaenopterid whales that visit the St. Lawrence region principally feed in these productive waters and in the North Atlantic (Mitchell, 1975; Borobia et al., 1995). Mysticete whales probably fast, at least partially, during their yearly migration and their winter stay in south Atlantic waters (Lockyer & Brown, 1981; Gaskin, 1982). The blubber layer deposited during feeding ensures a constant energy supply during this fasting period (Lockyer et al., 1985). Thus, balaenopterid whales mobilize lipophilic contaminants accumulated from these northern regions, including the St. Lawrence, during their migration and reproductive period. Concentrations of individual CB congeners and other persistent OCs contaminants were determined in blubber biopsy samples taken from minke (Balaenoptera acurostrata), fin (Balaenoptera physalus), blue (Balaenoptera musculus), and humpback (Megaptera novaeangliae) whales summering in the Gulf of St. Lawrence, Qutbec. Biopsies provide fresh blubber samples from presumably healthy whales, and contaminant data from biopsies were previously shown to be representative of contamination throughout the entire blubber mantle of balaenopterid whales (Gauthier et al., 1997). Interspecific differences in contaminant concentrations and patterns are discussed in relation to feeding ecology and metabolic capabilities of balaenopterid species. Gender differences in contamination and contaminant data for adult females and calves of humpback whales are discussed in terms of reproductive transfer to the offspring.

MATERIALS AND METHODS

Study area and biopsy sampling

Biopsies were collected in the summer and fall of 1991 and 1992 from 50 free-ranging northwestern Atlantic balaenopterid whales in the northwestern portion of the Gulf of St. Lawrence, QuCbec, Canada (Fig. 1) by personnel at the Mingan Island Cetacean Study Chlorinated organic contaminants in blubber biopsies 203

(MICS). In 199 1, a total of 46 biopsy samples were taken from 21 minke whales (Godbout region: 1; Mingan region: 20), 15 fin whales (Godbout: 1; Mingan: 14), two blue whales (Sept-Iles: 1; Mingan: l), and eight humpback whales (Mingan: 8). In 1992, four samples were collected from blue whales in the Mingan area. Whales were approached with five-meter hard-bottom inflatable boats equipped with 70 or 90 hp Yamaha outboard motors using an approach method described previously (Sears et al., 1990). All whales, except for minke whales, were photographed (Sears et al., 1990) and identification features were recorded to identify individuals so that whales were not biopsied twice in this study. Biopsy samples were taken from a distance of 620 m using a small stainless steel biopsy tip fired from a 76cm long, 1.8 kg Barnett Wildcat bow. The cross-bow and biopsy tip used in this study were similar to equipment described by Pals- boll et af. (1991). The arrow was kept afloat after it became dislodged from the whale blubber with a buoyant, aerodynamic, cone-shaped stop collar designed to limit the penetration of the biopsy tip in the whale. The tip was cleaned with ethanol between each shot to minimize wound infection and cross-contamination of the samples. Following biopsy, skin was cut from the blubber, placed in a dimethyl sulphoxide (DMSO)/saline solution and stored at 4°C. Skin samples were flown to Denmark for sex determination by Per Palsboll and Martine B&rub&at the University of Copenhagen using the polymerase chain reaction (PCR) with SRY gene primers (Palsbsll et al., 1992). Blubber samples were wrapped in solvent-washed aluminium foil and frozen at -15°C until forwarded to Trent University, Peterborough, Ontario for analysis. Biopsy samples yielded an average of 0.25 g (0.035-0.582 g) of blubber.

A f/antic Ocean

Fig. 1. Map of study area - biopsies were taken from balaenopterid whales in three regions of the northwestern Gulf of St. Lawrence, QuCbec: Mingan region (shaded), Godbout region (x), and Sept-Iles region (x). 204 J. M. Gauthier et al.

Contaminant analysis

Procedures for preparation of blubber samples for analysis were similar to those described by Gauthier et al. (1997). Briefly, samples were extracted with hexane in a Soxhlet appa- ratus and lipids were removed from the extracts by GPC on Biobeads SX-3. Lipid content of the sample was estimated by gravimetric analysis of the lipid fraction from the GPC column. After GPC, extracts were subfractionated by silica-gel column chromatography. Silica-gel Fraction A contained CBS, aldrin, hexachlorobenzene (HCB), heptachlor, mirex, and the majority of p,p’-DDE, while Fraction B contained the remainder of the DDE, heptachlor epoxide, isomers of hexachlorocyclohexane (HCH), chlordane compounds, dieldrin, p,p’-DDT, p,p’-DDD and methoxychlor. Non-ortho CB congeners were isolated from the silica gel Fraction A prepared from six selected minke whale samples using a carbon column (AX-21) subfractionation technique described previously (Gau- thier et &1997). The or&-substituted CBS and the other OC compounds were analyzed by HRGC- ECD using a Varian model 3500 GC with a 30 m DB-5 column (0.25 mm ID, 0.25 pm film thickness) using GC conditions described previously (Janz et al., 1992). CB congeners 3 1, 52, 49, 44, 66, 101, 87, 110, 151, 118, 153, 105, 138, 180, 170, 201, 195, 194 and 209 were quantified against a CLB-1 standard purchased from the National Research Council, Halifax, Canada. Quantification of other OC compounds was done by comparison with standards obtained from the Canadian Wildlife Service, Hull, Quebec. Chromatograms of silica-gel Fractions A and B from a male fin whale blubber biopsy sample (BP9131), as analyzed by HRGC-ECD with a 30m DB-5 column, are shown in Fig. 2. Non-ortho CB congeners 8 1, 77, 126 and 169 were analyzed by GC-ECD on a 60 m DB-5 as described for ortho CBS, with an analytical standard prepared from CB congeners purchased from Ultra Scientific, Rhode Island. Non-o&o CB congeners were not confirmed by CC-MS.

DDE A B

Fig. 2. Chromatograms of silica-gel Fractions A and B from a male fin whale blubber biopsy sample (BP9131), as analyzed by HRGC-ECD with a 30m DB-5 column. Major CB congeners (IUPAC number) and OC compounds are indicated on Fraction A and Fractions A and B, respectively. Chlorinated organic contaminants in blubber biopsies 205

Procedural blank samples were run during the course of this study. Extraction efficiencies for all analytes, including non-ortho CBS, were determined to be > 85% by analysis of spiked samples, but data are reported without correction for extraction efficiencies. CB congeners 101, 138, 153, 170 and 180 in cod liver oil reference material (SRM 1588) were quantified within f 5% of their certified concentrations. Limits of detection (LOD) calculated according to Keith et al., (1983) for ortho-substituted and non-ortho substituted CB congeners were between 0.3-l ng g-’ and 0.01&0.03 ng gg’, respectively. LODs for p-p’DDT, p-p/DDE, p-p’DDD, methoxychlor and dieldrin were between 0.61.2ng g-i, and LODs for all the other OC compounds were between 0.35- 0.55 ng g-l.

Data manipulation and statistical analysis

Concentrations of CBS and OCs were lipid-normalized (ng gg’ lipid). CPCB was calculated as the sum of the 19 ortho-substituted congeners analyzed. CDDT was calculated as the sum of the concentrations of DDT, DDD and DDE. CHCH was calculated as the sum of the four HCH isomers, and Cchlordane was calculated as the sum of trans-chlordane, cis-chlordane, trans-nonachlor, cis-nonachlor and oxychlordane. The relative proportions (%) of the individual compounds within each of these analyte classes were also determined. Proportions of CB congeners to congener 153 were calculated as Ratio’53 = [CB-Xj/[CB-1531. Concentrations of HCB, dieldrin, methoxychlor and mirex were presented individually. Prior to statistical analysis, non-detectable (ND) concentrations were replaced by ran- dom numbers between 0 and the LOD, as recommended by Sharaf et al. (1986). Mean concentrations and standard deviation about the mean were calculated for all compounds analyzed for each whale species and gender group. Untransformed and transformed data did not meet the criteria of normality and homoscedasticity for parametric statistical analysis, so further statistical analysis was done with non-parametric techniques. The Kruskal-Wallis test (a = 0.05) was used to test for interspecific differences in concentrations of CPCB and OCs. A minimum sample size of three males and three females was not available for the blue whale species. Sample sizes for females and males within each of the other species were relatively small, particularly for the humpback whale species. Therefore, data for all male whales and all female whales were pooled separately, and the Mann-Whitney U test (a = 0.05) was used to test for differences in contaminant concentrations between sexes. All statistical analysis was con- ducted using Systat software (v.5, Systat Inc., Evanston, IL).

RESULTS

Concentrations (ng gg’ lipid) of ortho CB congeners and OC compounds in individual whales are shown in Tables 1 and 2, respectively. Means and standard deviations of concentrations of CPCB, CDDT, Cchlordane, CHCH, dieldrin, HCB, methoxychlor and mirex in each balaenopterid species, and Kruskal-Wallis test results are presented in Table 3. Similar data for pooled male and pooled female whales and Mann-Whitney test results are presented in Table 4. Data for aldrin and heptachlor are not presented since concentrations of these analytes were below detection limits in all samples. _. .- --.-

622 aN aN 9

83dX 602 IOZ Pi51 S61 OLI 081 8tYl 501 t‘s1 811 ISI OII L8 IO1 99 6ti PP ZS IE

JO uo$aa u~alsamyl~oN aql u! paidtmg saiqM p!Jaldouaeiea pmp!h!puI JO sa!sdo!a u! a3dx pue slaua8uo3 83 JO (p!d!i ,_% &I) uoge.IluacmoD I 318V.L TABLE l-contd.

BP91 I8 M 88 II 80 18 23 63 391 49 69 66 78 183 ND 189 I24 29 4 9 ND ND 1388 BP91 19 M 73 13 189 48 95 168 723 105 178 130 324 582 33 475 265 65 ND 20 ND 4 3431 BP9123 F 62 ND 81 14 I8 79 418 47 78 68 117 359 ND 238 139 40 8 ND ND ND 1704 BP9131 M 49 19 154 29 32 135 629 80 80 114 211 348 ND 368 191 51 6 17 ND 2 2466 BP9132 M 57 19 46 13 18 36 203 29 46 45 75 141 ND 130 74 I8 3 7 ND ND 913 BP9133 M 72 3 82 8 28 48 206 28 73 34 99 197 ND 150 87 26 6 13 ND 3 1091 BP9134 F 73 ND 20 3 8 11 66 9 18 13 29 55 ND 45 36 ND 2 4 ND ND 321 BP9135 M 30 35 945 77 231 688 1807 257 19 323 1021 2138 ND 1469 736 287 52 110 ND 26 10222 BP9153 M 40 36 687 67 45 559 1595 152 100 245 872 1787 ND 1311 587 230 23 63 ND ND 8359 BP91 56 F 60 ND 87 24 34 109 328 41 46 47 122 364 ND 226 131 46 6 20 ND ND 1630 BP9160 F 72 22 119 24 70 112 458 57 104 77 171 448 ND 242 104 29 3 6 ND ND 2045 BP91 113 F 60 II 178 II 20 120 502 40 60 76 257 913 ND 350 154 50 5 11 ND ND 2758 BM9114 M 57 28 316 15 24 183 697 39 58 129 487 848 ND 615 338 116 27 61 ND 20 4021 BM9llO9 M 64 15 102 17 24 65 379 33 177 70 143 198 ND 206 110 25 3 IO ND ND 1577 BM9201 F 21 ND 28 58 ND 48 187 21 ND 32 60 162 6 94 64 18 4 9 ND ND 791 BM9202 M 36 28 466 18 ND 327 1165 ND 179 186 704 1326 ND 925 449 162 34 75 ND 27 6071 BM9204 F 19 ND 52 ND ND 51 190 20 95 ND 69 141 ND 106 78 28 7 13 ND ND 850 BM9222 M 33 71 303 6 ND 146 530 16 130 112 309 393 ND 366 190 63 15 32 ND 13 2695 MN91 13 F 27 77 223 56 171 200 1516 101 63 167 246 534 ND 252 187 58 10 21 ND ND 3882 MN9122 M 63 16 73 21 31 82 229 26 99 ND 107 257 ND 161 51 21 ND 4 ND ND 1178 MN9127 M 51 ND Ill 17 31 89 270 39 60 45 201 236 ND 230 47 21 ND ND ND ND 1397 MN9128 M 32 37 175 65 94 172 710 86 256 109 265 310 ND 321 147 33 ND 6 ND ND 2787 MN9130 M 59 9 316 9 28 200 741 44 292 122 583 1218 ND 497 703 159 26 67 ND ND 5015 MN9151 F 45 ND 72 16 ND 90 258 25 84 43 163 286 ND 280 217 47 6 13 ND ND 1601 MN9164 F 37 61 217 34 35 179 1042 86 ND 91 197 329 ND 274 126 30 ND 5 ND ND 2705

Whale species: BA = minke, BP = fin, BM = blue, MN = humpback. Year: 91 = 1991, 92 = 1992. All whales were sampled in the Mingan region, except for whales BA91114 and BP91 113 sampled in the Godbout region and whale BM91109 sampled in the Sept-Iles region. TABLE 2 Concentration (ng g-t lipid) of Organochlorine Compounds in Biopsies of Individual Belaenopterid Whales Sampled in the Northwestern Region of the Gulf of St Lawrence

Whale Sex Organochlorine compound

HBC Mirex DDT DDE DDD CDDT Meth a- B- Y- S- CHCH Dield hEpo t-chl c-chl oxyc t-nona c-nona Cchl HCH HCH HCH HCH

BA9138 M 146 15 166 1617 221 2004 9 106 34 21 2 163 6 ND 42 168 183 409 224 1026 BA9139 F 98 13 167 1319 257 1743 ND 126 24 24 ND 174 6 ND 30 166 180 413 223 1012 BA9140 F 102 4 77 659 132 868 8 112 20 23 3 158 2 ND 21 102 104 210 113 551 BA9141 M 99 8 98 793 168 1059 ND 124 17 23 7 171 6 ND 22 112 115 201 123 573 BA9142 F 129 10 150 1118 145 1413 ND 123 18 20 ND 161 5 ND 30 146 121 254 161 712 BA9143 M 129 13 159 1366 280 1805 22 138 35 30 4 207 ND 2 54 235 172 362 213 1035 BA9144 F 122 6 143 1120 225 1488 31 130 25 20 4 179 7 ND 27 161 156 289 98 731 BA9145 F 148 37 223 2021 359 2602 ND 71 23 14 5 112 10 ND 14 87 132 161 144 537 BA9146 F 185 63 496 1753 761 3010 58 145 70 27 3 244 27 ND 40 180 282 384 311 1199 BA9147 M 131 13 158 1304 271 1732 ND 118 29 26 5 177 23 ND 30 179 168 182 213 771 BA9148 F 96 5 74 719 156 949 ND 126 24 24 5 179 ND ND 22 115 103 123 119 481 BA9149 F 102 7 81 651 142 873 ND 114 23 19 ND 156 ND ND 19 102 83 148 102 454 BA9150 F 71 5 114 986 178 1278 ND 93 23 18 ND 135 ND ND 20 110 113 227 140 610 BA9152 F 89 13 120 923 212 1255 ND 106 29 20 ND 155 388 ND 31 142 130 103 150 555 BA9155 F 23 17 125 483 228 835 62 89 11 12 4 116 229 ND 36 149 124 147 170 627 BA9157 F 71 7 91 892 169 1152 ND 94 19 18 ND 133 264 ND 24 105 101 114 137 481 BA9158 F 69 18 106 994 183 1284 ND 96 18 17 ND 133 300 ND 31 119 115 120 155 540 BA9159 F 86 6 45 461 82 587 8 89 17 15 ND 121 220 ND 16 78 63 49 74 280 BA9162 M 90 4 170 697 300 1168 50 169 35 32 4 240 349 ND 17 72 85 122 100 396 BA9163 F 67 79 86 1134 287 1508 26 104 17 19 2 143 280 ND 11 83 96 60 120 370 BAOl114 F 75 77 265 3593 472 4330 52 117 24 24 6 170 352 ND 22 136 122 24 167 470 BP9107 M 58 5 170 694 341 1204 29 150 ND 26 ND 177 536 ND 33 93 174 114 152 566 BP91 16 M 71 6 793 2473 1653 4919 119 177 93 24 44 339 959 29 328 374 350 300 375 1727 BP91 17 F 11 ND 72 188 392 651 232 277 ND 47 ND 325 445 ND 185 305 121 135 146 892 BP91 18 M 82 6 138 1604 186 1928 53 122 14 18 5 160 305 ND 8 32 46 21 63 170 TABLE 2-contd.

BP91 19 M 114 I1 168 2904 360 3432 57 133 27 22 5 188 496 ND 21 58 106 22 120 328 BP9123 F 7.5 6 228 2261 211 2700 48 90 16 16 ND 123 261 ND 4 27 53 19 66 169 BP9131 Ml25 5 159 3256 300 3716 21 105 22 15 9 151 472 ND 8 44 72 34 89 247 BP9132 M 34 2 123 756 428 1307 ND 173 ND 37 11 221 583 ND 110 166 139 54 168 637 BP9133 M 44 3 341 993 1258 2592 89 195 81 30 ND 306 1128 ND 15 70 234 51 245 614 BP9134 F 11 ND 123 509 352 984 52 221 36 39 7 303 452 ND 111 133 121 63 107 535 BP91 35 M 318 42 230 11239 1617 13086 ND 133 140 77 26 376 1145 ND 44 176 207 73 286 786 BP91 53 M 255 27 243 10623 1444 12310 ND 114 65 22 ND 202 984 ND 34 137 249 258 347 1024 BP91 56 F 52 5 27 3692 200 3919 19 83 11 13 ND 108 186 ND 16 55 45 23 75 214 BP9160 F 97 2 82 1306 173 1561 21 114 19 20 3 156 301 ND 8 82 102 52 107 351 BP91113 F 96 3 89 2601 185 2875 ND 61 14 9 ND 85 236 ND 10 31 89 55 64 248 BM9114 M 186 24 796 2635 560 3991 ND 61 40 10 ND 113 572 ND 14 44 154 148 166 527 BM91109 Ml37 2 197 2162 192 2551 15 79 20 17 ND 117 364 ND 11 59 77 31 91 269 BM920 1 F 53 ND 279 888 351 1518 245 109 134 38 55 336 245 ND 56 82 65 144 138 485 BM9202 M 378 22 1723 4966 1770 8454 ND 86 84 22 ND 192 1230 ND 48 114 296 405 319 1181 BM9204 F 44 ND 445 1138 536 2120- ND 78 ND 21 ND 108 251 ND 12 46 52 50 85 245 BM9222 Ml63 4 967 2586 1054 4608 18 72 40 46 ND 159 567 ND 23 61 136 47 137 404 MN9113 F 448 27 221 2537 321 3079 ND 147 84 26 ND 259 1144 ND 49 145 394 638 352 1578 MN9122 M 73 ND 137 1422 316 1876 31 130 21 23 ND 174 407 ND 18 102 139 227 121 608 MN9127 M 94 ND 386 1359 1380 3125 104 336 63 67 9 475 1524 ND 69 166 375 492 325 1428 MN9128 M 227 4 148 2156 311 2615 19 204 28 36 ND 269 494 ND 37 143 183 264 156 783 MN9129 F 38 11 73 1157 128 4460 ND 43 31 9 ND 83 521 ND 14 47 198 344 187 790 MN9151 F 35 3 56 1239 156 1451 26 55 ND 12 7 75 117 ND 10 41 53 135 41 279 MN9164 F 370 2 132 2200 326 2659 12 132 73 18 ND 224 798 ND 37 104 245 487 209 1081

Whale species: BA = minke, BP = fin, BM = blue, MN = humpback. Year: 91 = 1991, 92 = 1992. All whales were sampled in the Mingan region, except whales BA91114 and BP91 113 sampled in the Godbout region and whale BM91109 sampled in the Sept-Iles region. Meth = methoxychlor, dield = deildrin, hEpo = heptachlor epoxide, c- = cis-, t-; = tram-, chl = chlordane, nona = nonachlor, oxyc = oxychlordane. 210 J. M. Gauthier et al

PCBs

Concentrations of CPCB (sum of 19 or&o-substituted congeners) in biopsy samples from individual balaenopterid whales were between 0.2-10.2~g g-l lipid (Table 1). Two male fin whales, one male blue whale, and one female minke whale were found to have

TABLE 3 Means and Standard Deviations about the Mean (in brackets) of Lipid Content (%) and Concen- trations CPCB and OC Compounds (ng g-t lipid) in Balaenopterid Whale Species, and Kruskal- Wallis Test Results for PCB and OC Concentrations

Whale species Kruskal- Wallis test results Minke Fin Blue Humpback (a = 0.05) n 21 6 8 % lipid 60(9) 62& 39(19) 43(13) EPCB 2702( 1498) 2674(2850) 2668(2070) 2497( 1379) N.S. EDDT 1569(861) 38 12(3908) 3874(2528) 2578( 1025) 0.004 Cchlordane 639(245) 567(420) 5 18(344) 859(476) N.S. EHCH 163(35) 215(92) 171(87) 207( 134) N.S. Dieldrin 298(57) 566(328) 538(369) 641(491) N.S.h HCB lOl(35) 96(82) 1 lO(55) 177(147) N.S. Methoxychlor 16(22) 50(6 1) 46(97) 24( 34) N.S. Mirex 20(24) 8(11) 9(11) 6(9) 0.006

‘VI = 8. hMinke whales were excluded from statistical analysis because of the unusual dieldrin concentrations in 13 of 21 biopsy samples from minke whales (see Table 2).

TABLE 4 Mean and Standard Deviation (in parentheses) of Lipid Content (%) and Concentrations of CPCB and OC Compounds (ng g-t lipid) in Female and Male Balaenopterid Whales (data for all male and female whales were pooled separately), and Mann-Whitney U Test Results for PCB and OC Concentrations

Sex Mann- Whitney U test results Female Male (a = 0.05) n 28 % lipid X(16) $5,

CPCB 2274( 1507) 3145(2419) N.S. CDDT 1787(987) 3727(3341) 0.003 Cchlordane 572(327) 722(392) N.S. EHCH 166(70) 212(92) 0.021 Dieldrin 380(304) 723(360)h 0.002’ HCB 103(96) 140(87) 0.021 Methoxychlor 32(62) 29(36) N.S. Mirex 15(22) lO(11) N.S.

+t = 19 (7 minke, 6 fin, 2 blue and 4 humpback whales). ‘n = 18 (1 minke, 9 fin, 4 blue and 4 humpback whales). ‘Minke whales were excluded from statistical analysis because of the unusual dieldrin concentrations in 13 of the 21 biopsy samples. Females: n = 12, males: n = 17. Chlorinated organic contaminants in blubber biopsies 211

CPCB concentrations in blubber > 6 pg gg’ lipid. There were no significant differences in concentrations of CPCB among the four balaenopterid species (Table 3). Although mean XPCB concentrations were higher in pooled male whales than in pooled female whales, these differences were not significant (Table 4). CB congener analytes were present at detectable concentrations in all balaenopterid species, with the exception of CB congeners 105,201 and 209 (Table 1). Mean proportions of CB congeners (minus congeners 105, 201 and 209) in each balaenopterid species are illustrated in Fig. 3. Di-ortho-substituted CB congeners 52, 101, 153, 138 and 180 plus mono-ortho congener 118 accounted for 79% of CPCB in the blubber of these whales. Patterns of CB congeners were similar between balaenopterid species (Fig. 3) and between pooled sexes (not shown). Patterns for Ratio’53 values were very similar to those calculated for proportions of congeners to CPCB (not shown). Mean concentration ratios of CB 52/153, CB 118/153 and CB 138/153 in balaenopterid whales were 0.33rtO.22, 0.45*0.16 and 0.72 f 0.16, respectively. CBS were analyzed in biopsies of two calves and two adult female humpback whales. To our knowledge, the adult female whales were not the mothers of the calves. Concentra- tions of CPCB were similar or higher in the calves (MN9127: 1.4 pg gg’ lipid and MN91 28: 2.8 pg g-r) compared to the adult females (MN9129: 1.4 pg gg’ and MN91 51: 1.6 ,ug gg’) (Table 1). CB congener patterns were generally similar between the two calves, but there were higher proportions of tri- to pentachlorobiphenyls (with the exception of congeners 110 and 118) and hexa-CB 151 in the calves than in the adult female whales (Fig. 4). Mean concentrations of the sum of non-ortho CBS in biopsy samples from three male and three female minke whales were 1.97 i 0.78 ng gg’ lipid, which is less than 0.1% of CPCB. In all samples, congener 77 was present at the highest concentration among

31 52 49 44 66 101 87 110 151 118 153 138 180 170 195 194 CB congener

0 minke Otin H blue t# humpback 1

Fig. 3. Mean relative proportions of individual CB congeners to CPCB in minke, fin, blue and humpback whales. 212 J. M. Gaufhier et al. non-ortho CBS, with the exception of a female minke whale in which non-ortho congener 81 was the dominant congener. Mean concentrations (ng g-’ lipid) of the individual non- ortho congeners were 1.00 ~1~0.69for CB 77, 0.41*0.15 for CB 126, 0.29 f 0.16 for CB 81, and 0.23 *to.17 for CB 169. Similar mean concentrations of the sum of non-ortho CBS were found for the three females (2.0ng g-’ lipid) and the three males (1.9 ng 8-l). Mean concentration ratios of CB 77/l 53 and CB126/153 were 2.11 f 1.48x 10m3 and 6.03 f 2.25 x lOA, respectively.

DDT compounds

Concentrations of CDDT ranged from 0.59 to 13.1 pg g-’ lipid in biopsy samples of individual balaenopterid whales (Table 2). Samples from two male fin whales and one male blue whale had the highest CDDT concentrations, at 8.5, 12 and 13 hg g-’ lipid. Concentrations of CDDT in the four balaenopterid species differed significantly (Table 3). Minke whales had the lowest mean concentrations of CDDT, humpback whales were intermediate, and fin and blue whales had the highest concentrations. Pooled males had significantly higher concentrations of CDDT than pooled females (Table 4). Mean concentrations of CDDT and CPCB were similar in humpback whales (CDDT/CPCB = 1.16 rfr0.50), but the mean EDDT concentration was only 40% of the mean CPCB concentration in minke whales (XDDT/CPCB = 0.601tO.11). Mean EDDT concentrations were about 40% higher than mean CPCB concentrations in fin and blue whales (EDDT/CPCB = 1.68+0.69 and 1.69&0.51, respectively). Mean ratios of CDDT/CPCB were similar in pooled females (1.04 & 0.76) and in pooled males (1.24 f 0.52). 301

31 52 49 44 66 101 87 110 151 118 153 138 180 170 195 194 CB congeners

H MN calves El MN females

Fig. 4. Mean relative proportions of individual CB congeners to CPCB in humpback whale calves (n = 2) and in adult female humpback whales (n = 2). Chlorinated organic contaminants in blubber biopsies 213

DDE was the predominant compound in the DDT class, comprising on average 72% of CDDT (Fig. 5). In blue whales, DDT comprised 20% of CDDT, compared to 7-8% in the other balaenopterid species (Fig. 5). Mean ratios between proportions of DDT and DDE were about two times higher in blue whales (0.3OAO.11) than the other balaenopterid species (0.13 A~0.09). Proportions of DDD were similar in all balaenopterid species. Mean relative proportions of the different DDT compounds were very similar for pooled female and pooled male data (not shown).

Chlordane compounds

Concentrations of Xchlordane ranged from 0.2 to 1.7 pg g-l lipid in biopsies from individual balaenopterid whales (Table 2). There were no significant differences in Xchlordane concentrations in the four whales species (Table 3) and between pooled female and male whales (Table 4). Cis-nonachlor, trans-nonachlor, oxychlordane, cis-chlordane and trans-chlordane comprised, on average, 27, 26, 23, 19 and 6%, respectively, of Cchlordane in whale biopsies. Patterns of chlordane compounds varied between balaenopterid species (Fig. 6). Cis-nonachlor was the major chlordane compound in the fin and blue whale species (31%) but trans-nonachlor comprised the greatest proportion of Xchlordane in minke and humpback whales (29 and 41%, respectively). Mean ratios between proportions of oxychlordane and trans-nonachlor were highest in fin whales (2.11 i 1.26) intermediate in blue (1.45 f 1.01) and minke (0.97 kO.97) whales, and lowest in humpback whales

100

T _

DDE DDD DDT

q lminke q itin q blue H humpback

Fig. 5. Mean relative proportions of DDT compounds to CDDT in minke, fin. blue and humpback whales. 214 J. M. Gauthier et al.

J oxychl t-&lord c-&lord t-nonac c-nonac

Omit&e Elfin Hbblue El humpback

Fig. 6. Mean relative proportions of chlordane compounds to Ezhlordanes in minke, blue and humpback whales. Oxychlo = oxychlordane, t-chlord = trans-chlordane, c-chlord = cis-chlordane, t-nonac = trans-nonachlor, c-nonac = cis-nonachlor.

(0.61 f 0.17). Trans-nonachlor was the dominant chlordane compound in pooled females and cis-nonachlor was the dominant compound in pooled males, but differences in chlordane patterns between sexes were small (Fig. 7). Mean ratios between proportions of oxychlordane and truns-nonachlor were similar in pooled females (1.16 f 0.95) and in pooled males (1.57& 1.32).

HCH compounds

Concentrations of EHCH in individual whale biopsies ranged between 76 to 475ng gg’ lipid (Table 2). Concentrations of EHCH were statistically similar among whale species (Table 3) but pooled male whales had significantly higher concentrations than pooled female whales (Table 4). wHCH was the dominant HCH compound and accounted on average for 67% of EHCH. Relative proportions of individual HCH isomers were homogeneous among whale species, except for blue whales. In minke, fin and humpback whales, the a-HCH isomer comprised about 70% of EHCH, but this isomer only comprised 50% of CHCH in blue whales (Fig. 8). Mean ratios between proportions of p-HCH and o-HCH were higher in blue whales (0.61*0.45), than in fin (0.26*0.28), humpback (0.29hO.28) and especially minke (0.22 kO.08) whales. Mean proportions of /I-HCH/ CHCH were slightly lower in pooled females (13.6% f 7.6%) than in pooled males (20.1% f 10.8%) (not shown). Mean ratios between proportions of @-HCH and a- HCH were similar in pooled females (0.21 +0.14) and pooled males (0.35 f 0.27). Chlorinated organic contaminants in blubber biopsies 215

t-&lord c-&lord t-nonac c-nonac

Cl female q male

Fig. 7. Mean relative proportions of chlordane compounds to Cchlordanes in male and female balaenopterid whales (data for male and female whales were pooled separately).

80 &6 _;; 70 r g 60 E” 8 50 5 z 40 er 0 .Cg 30 t: 2,o 20 LL 10

0 OL-HCH fi -HCH d -HCH g -HCH

q lminke Ofin ablue S humpback

Fig. 8. Mean relative proportions of HCH compounds to CHCH in minke, fin, blue and humpback whales. 216 J. M. Gauthier et al.

Other OC compounds

In biopsies from eight minke whales, concentrations of dieldrin ranged between 229- 388 ng g-’ lipid (Table 2). However, 13 minke whale samples showed unexplainably low concentrations of dieldrin, ranging from non-detectable to 28ng gg’ lipid. Minke whale samples were therefore excluded from further statistical analysis. Dieldrin concentrations in whales of the other three species ranged from 117 to 1524 ng g-’ lipid (Table 2). Diel- drin concentrations were similar between these three species (Table 3), but were significantly lower in pooled females than in pooled males (Table 4). HCB concentrations in individual balaenopterid whale biopsies ranged between 11448ng g-’ lipid (Table 2). Similar HCB concentrations were found in the four balaenopterid species (Table 3). HCB concentrations in pooled males were statistically higher than in pooled females (Table 4). Methoxychlor was present at detectable concentrations in about half of the whale biopsies (Table 2). No significant differences in methoxychlor concentrations were found between balaenopterid species (Table 3), or between sexes (Table 4). Mirex was detected in most biopsies and concentrations ranged up to 79 ng g-l lipid (Table 2). Mirex concentrations were higher in minke whales, and differences in concentrations between whale species were significant (Table 3). There were no significant differences in mirex concentrations in pooled females and males (Table 4).

DISCUSSION

Although contaminant concentrations in biopsy samples from baleen whales have been reported in other recent studies (Woodley et al., 1991; Marsili & Focardi, 1996), these biopsy data are rare. Most contaminant monitoring data for balaenopterid species have been obtained from stranded whales or through whaling activities, and include a limited number of analytes. Although balaenopterid whales that feed in the St. Lawrence may also feed elsewhere in the northwestern Atlantic, yearly photo-identification studies in the Gulf of St. Lawrence indicate that whales show summering site fidelity (Sears et al., 1987; Katona & Beard, 1990). Many photo-identified whales biopsied in the Mingan region had been resighted several times in the past 17 years by MICS. Thus, contaminants analyzed probably have originated, at least in part, from the St. Lawrence, but may also represent contamination of nortwestern Atlantic prey. Concentrations of ZZPCB, CDDT and mirex in whale biopsies from this study were similar to concentrations found in blubber of balaenopterid whales stranded in the St. Lawrence region between 1983 and 1990, with the exception of some minke whales which had higher PCB concentrations (-5-1Opg gg’ wet wt) (B&land et al., 1992). Two stranded minke whales from the North Pacific sampled in the 1990s had similar concentrations of EPCB and Echlordane, and concentrations of CDDT were similar or higher (2.8 and 8.3pg gg’ wet wt) than in minke whales of this study (Varanasi et al., 1993). Biopsy samples taken in the early 1990s from fin whales of the Mediterranean Sea had a similar lower range for EPCB (-0.5-15 pg g-l dry wt) and EDDT (-0.2-22pg gg’ dry wt) (Marsili & Focardi, 1996) as in fin whales of this study. Concentrations of CPCB and CDDT in northeastern Atlantic fin whales sampled in the mid-1980s (0.5-2 pg g-l lipid) Chlorinated organic contaminants in blubber biopsies 217

(Aguilar & Borrell, 1988) were in the lower range of those found in fin whales of this study. Concentrations of non-o&o CB congeners in minke whale biopsies were similar to those found in a single male blue whale stranded in the Gulf of St. Lawrence region (Gauthier et al., 1997). Contrary to minke whales of this study, non-ortho CB congeners 77, 126 and 169 were not detected in the blubber of an Antarctic minke whale (Tanabe et al., 1987). Concentrations of XPCB and CDDT in stranded St. Lawrence odontocetes, such as pilot whales (Globicephala melaena), white-beaked dolphins (Lagenorhyncus acutus), and harbour porpoises (Phocoena phocoena) (B&land et al., 1992) were about ten and three times higher, respectively, than in balaenopterid whales of this study. XPCB, XDDT and mirex concentrations in stranded resident beluga whales (Delphinapterus leucas) of the St. Lawrence Estuary (Muir et al., 1996) were about 30, 15 and 100 times higher, respectively, than in balaenopterid whales. Contrary to odontocete whales, balaenopterid whales are seasonal feeders and prey upon lower trophic organisms (Mitchell, 1975). Belugas also feed on migrating eels which are 10 times more contaminated than resident fish from the St. Lawrence (Hickie et al., 1991). Lipid contents of minke, fin, blue and humpback whale blubber were in the same range as reported in the literature (Heyerdahl, 1932; Ackman et al., 1975; Henry & Best, 1983; Lockyer et al., 1985). Concentrations of CPCB and most OCs were similar between blue and fin whales, which mainly feed on euphausiids, and minke and humpback whales, which probably mainly feed on small schooling fish (Brodie, 1978; Breton, 1986; Borobia et al., 1995). Surprisingly, minke whales had lower concentrations of XDDT than fin and blue whales. Concentrations of CPCB, CDDT and dieldrin in blubber biopsies of North Atlantic right whales (Eubalaena glacialis) (Woodley et al., 1991) which feed on small zooplankton (mostly copepods), are about 10 times lower than in balaenopterid whales. Inter-specific differences observed in the ratios of CDDT/XPCB may reflect differences in feeding ecology but, to verify this, data are needed on PCB and DDT concentrations in fish and euphausiids from the Gulf of St. Lawrence and northwestern Atlantic regions. Mirex concentrations in minke whales were on average double those in the other balaenopterid whale species and this may be due to the fish-eating habits of minke whales. Trans-nonachlor was the major chlordane compound in humpback and minke whales, as with fish-eating marine mammals (Kawano et al., 1988; Muir et al., 1988). Overlapping prey preferences of balaenopterid species may explain the lack of clear differences in contamination among these whales. In general, proportions of the tri- to nonachlorobiphenyl groups to CPCB in balaenopterid whales of this study most closely resembled those found in Aroclor 1254 (Sil- berhorn et al., 1990). Two families of cytochrome P450-associated mono-oxygenases, the CYP2B and CYPlA enzymes, are involved in oxidative metabolism of CB compounds (McFarland & Clarke, 1989). These enzymes metabolize CBS in regions with two adjacent carbons without chlorine substitution (i.e. vicinal H atoms) at either the meta-para (CYP2B) or ortho-meta (CYPlA) positions (Boon et al., 1992, 1994). Patterns of CB congeners, both in proportion to XPCB and to persistent congener 153, in cetaceans and seals have been used to draw conclusions about the in-vivo metabolic capabilities of these animals (Boon et al., 1987, 1992, 1994; Tanabe et al., 1988; Duinker et al., 1989; Norstrom et al., 1992). High concentrations of congeners 153 and 180 in balaenopterid whales of this study are due to the lack of vicinal H atoms in these congeners. High concentrations of CB congeners 52 and 101 (unsubstituted at meta-para positions) in balaenopterid 218 .I. M. Gauthier et al. whales are consistent with the undetectable CYP2B activity in minke whales (Goksoyr et al., 1988). In contrast, CYPlA metabolic activity has been detected in minke whales (Goksoyr et al., 1988). The elevated concentration of congener 138 (unsubstituted at ortho-meta position) may reflect poor metabolism of congeners with more than one chlorine atom at ortho positions (Duinker et al., 1989; Boon et al., 1992). Although there are also high concentrations of the mono-ortho 118 (unsubstituted at ortho-meta position), values of Ratio’53 for this congener were lower than for CB 138. The homogeneous CB patterns in biopsies may indicate that there are no differences in the metabolic capabilities of the four balaenopterid species for CBS. Levels of microsomal cytochrome P-450 have been shown to be similar in five cetacean species, including four odontocete whales and minke whales (Goksoyr et al., 1988; Watanabe et al., 1989; White et al., 1994). In comparison with St. Lawrence fin whales, mean concentrations of CB congeners (pg g-i dry wt) in Mediterranean Sea fin whales (Marsili & Focardi, 1996) were about five times lower for congener 101, similar for congener 118 and two times higher for congeners 138, 153 and 180. This may be explained by differences in prey contamination between geographical regions and/or differences in metabolic activities induced by the higher contamination burden in Mediterranean fin whales. Ratioi53 values for congeners 52 and 118 were higher in balaenopterid whales than in harbour porpoises (Phocoena phocoena) (0.19 f 0.08 and 0.20 f 0.12, respectively) and common seals (Phoca vitulina) (0.07 +Z0.21 and 0.05 f 0.05) (Hall et al., 1992; Wells et al., 1994). However, concentration ratios of CB 138/153 in balaenopterid whales were similar to those of harbour porpoises (0.80&0.09) and common seals (0.68 *0.29), indicating common inability to metabolize ortho-meta unsubstituted congeners with more than one ortho chlorine. Concentrations of sum non-ortho CBS in minke whales were similar or lower than those found in several odontocete species, but concentration ratios of CB 77/l 53 are about three to 13 times lower in most odontocetes (Corsilini et al., 1995; Jarman et al., 1996; Muir et al., 1996). The relatively high proportions of non-ortho CB congener 77 in minke whales may be due to lower CYPlA induction in baleen whales compared to the more highly contaminated odontocete whales. However, differences between minke whales and odontocete whales for concentration ratios of CB 126/153 showed considerable variation (Corsilini et al., 1995; Jarman et al., 1996; Muir et al., 1996). Moreover, the non-ortho CB data in the present study must be interpreted with caution as there was no GC-MS con- firmation of data generated by GC-ECD analysis. DDE is the main DDT compound detected in baleen whales (Henry & Best, 1983; Aguilar & Borrell, 1988). Although blue whales had the highest CDDT concentrations of the four balaenopterid species, proportions of DDT/DDE were about three times higher in blue whales than most whales of the other species. This may indicate that blue whales have the least capacity for metabolizing DDT to DDE. However, this may also be due to feeding ecology since zooplankton have higher proportions of DDT/DDE than fish (Tanabe et al., 1984; Kawano et al., 1988). Trans-chlordane is the most readily metabo- lized chlordane compound (Tashiro & Matsumura, 1977) but this compound was present in higher proportions in balaenopterid species (4 to 8%) compared to odontocete whales (- 2%) (Kawano et al., 1988) and seals ( > lo/) (Muir et al., 1988). According to Kawano et al. (1988), greater metabolic capacity for chlordane compounds is characterized by high proportions of oxychlordane and low proportions of the persistent trans-nonachlor. Higher proportions of oxychlordane relative to trans-nonachlor in fin whales in compari- Chlorinated organic contaminants in blubber biopsies 219

son to humpback whales may indicate that fin whales more readily metabolize chlordane compounds. Proportions of rw-HCH in balaenopterid species (50 to 70%) were higher than in small cetaceans (12 to 40%) (Tanabe et al., 1984; Kawano et al., 1988). Since fi-HCH is the most persistent HCH isomer, higher ratios of /3-HCH/a-HCH indicate greater metabolism for HCH compounds (Tanabe et al., 1996). Ratios between proportions of j?-HCH and a-HCH in blue whales were higher than in minke whales, and this may indicate greater metabolism of a-HCH by blue whales or greater exposure to /I-HCH. However, zooplankton have very low proportions of B-HCH to XHCH (Tanabe et al., 1984; Kawano et al., 1988). Interpretation of the data on pooled females and pooled males is obscured by the species makeup of the two sexes and by the lack of age data for biopsied whales. Age modi- fies gender differences in the contamination of whales since concentrations decrease with age in females and increase with age in males (Tanabe et al., 1986; Aguilar & Borrell, 1988, 1994) due to periodic clearance of these contaminants during gestation and lactation. This may explain why the highest contaminant concentrations observed in this study were from two male whales. Although concentrations of CDDT were higher in male than female whales of this study, proportions of DDE and DDT and concentration ratios of CDDT/CPCB were similar between sexes. Similar results were obtained for mature northeastern Atlantic fin whales aged eight to 15 years old, but not for the older whales aged 16 years or more (Aguilar & Borrell, 1988). Reproductive transfer of DDT compounds was estimated to be greater than that of PCBs in fin whales (Aguilar & Borrell, 1994). In lactating grey seals (Hulicherus grypus), DDT compounds are transferred more efficiently from blubber lipids to milk lipids than PCBs (Addison & Brodie, 1977, 1987). Higher proportions of DDE and lower proportions of DDT in older males compared to older female whales (16 years old or more) result from increased metabolic activity induced by higher contaminant burden in males (Aguilar & Borrell, 1988). It is possible that the sample comprised few old whales. In this study, differences in CB patterns were not observed in male and female whales, even though differences in CYPlA metabolic activity have been observed between the sexes of other marine mammal species (Goksoyr et al., 1992; White et al., 1994). The homogeneous pattern of DDT, chlordane and HCH compounds and the similar ratios between proportions of oxychlordane/trans-nonachlor and proportions of /$HCH/ CX-HCH in biopsies from pooled males and females may also indicate similar metabolic capabilities for these OC compounds in both sexes. The lower concentrations of CDDT, CHCH, dieldrin and HCB in female balaenopterid whales may be due to elimination of these compounds through reproductive transfer. HCB and HCH compounds were found to be more readily transferred from female blubber to the placenta of striped dolphins (Stenellu coeruleoalba) than the higher molecular weight and more lipophilic compounds such as PCBs and DDTs (Tanabe et al., 1982). Contrary to placenta lipids, cetacean milk is rich in non-polar triglyceride lipids (Kawai et al., 1988). Thus, compounds with higher molecular weights and high blubber lipid solubility are transferred more readily to non-polar lipids of milk, and therefore to the offspring (Addison & Brodie, 1987). Because lactational transfer of OC compounds is more important than gestational transfer, this may explain why differences in concentrations of CDDT and dieldrin between female and male balaenopterid whales were greater than for HCB and XHCH. 220 J. M. Gauthier et al.

Subramanian et al. (1988) studied CB patterns in a mother/calf pair of Dali’s porpoise (Phocoenoides dalli), and suggested that there was preferential transfer through gestation and lactation of lower chlorinated CB congeners (tri- to pentachlorobiphenyls) from the mother to the offspring. Although the two adult female humpback whales that were sampled in this study were not the mothers of the biopsied humpback calves, differences in CB congener patterns between the calves and females were consistent with observations by Subramanian et al. (1988). XPCB concentrations in humpback calves were similar or higher than in adult females which may indicate that CBS, and especially the lower chlorinated congeners, are readily transferred to calves through gestation and lactation. The biopsy technique used in this study was a good monitoring tool for persistent lipophilic contaminants in whales. However, some aspects of inter- and intra-specific variation in contamination remain unclear. A greater sample size would aid in further interpretation of the data and would permit intra-specific comparisons within each species. An important limitation of this technique is the lack of data on the age of biopsied whales, but length estimation at sea can give some information on age groups (Marsili & Focardi, 1996). The biopsy technique could be used to study differences in contaminant patterns in female whales and their offspring, and to investigate seasonal and temporal changes in cpntaminant concentrations in the long-lived mysticete whales. In addition, this technique provides an opportunity to investigate spatial variations in contaminants in whales at the regional and global levels.

ACKNOWLEDGEMENTS

We would especially like to thank personnel at the Mingan Island Cetacean Study (MICS) who helped in collecting biopsy samples, and Tracy Metcalfe for the analysis of non-ortho CBS. We thank Brendan Hickie, and especially Ross Norstrom, for advice and sugges- tions on the manuscript. The map was drawn by Simon Labelle. This work was funded by a research grant to C. D. Metcalfe from the Science Subvention fund of the Canadian Department of Fisheries and Oceans, and from an Operating Grant to CDM from the National Science and Engineering Research Council (NSERC) of Canada. Graduate support for J. M. Gauthier was supplied by Fonds pour la Formation de Chercheuses et Chercheurs et 1’Aide B la Recherche (FCAR), Quebec.

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