Otolith stratigraphy of Late Weichselian and Holocene sediments of Malangsdjupet, off northem Norway
PIETER A. M. GAEMERS & TORE O. VORREN
Gaemers, P. A. M. & Vorren, T. 0.: Otolith stratigraphy of Late Weichselian and Holocene sediments of Malangsdjupet, off northern Norway. Norsk Geologisk Tidsskrift, Vol. 65, pp 187-199. Oslo 1985. ISSN 0029-196X.
Otoliths of eleven fish species have been identified in cores recovered from the trough Malangsdjupet (dose to 70°N) on the Norwegian continental shelf. The codfish family (Gadidae) dominates with eight species. Three acmc-zones bclonging to the Mer/angius merlangus Lineage-Zone are establishcd: the Boreogadus sp. Acme-Zone (about 15,000 or 14,000 to 10,000 years B. P.), the Neocolliolus esmarki Acme-Zone (10,000 to 7,800 years B. P.) and the Micromesistius poutassou Acme-Zone (7,800B. P. to present). The Boreogadus sp. Acme-Zone reflects an arctic environment while the two others reflect boreal conditions. The M. poutassou Acme-Zone represents a more oceanic environment than the carly Holocene N. esmarki Acme-Zone.
P. A. M. Gaemers, Rijksmuseum van Geologie en Mineralogie, Hooglandse Kerkgracht 17, 2312 HS Leiden, the Netherlands. T. O. Vorren, Institute of Biology and Geology, University of Tromsø, P. O. Box 3085 Guleng, N-9001 Tromsø, Norway.
Studies of otoliths from the present sea floor and Material and methods the youngest Quaternary sediments are few in number. Jensen (1905) described otoliths from Twenty-seven gravity cores (diameter 100 mm) an area between Jan Mayen, Iceland and the from ten stations (Fig. lB) were investigated for Faroes, and many years later Wigley & Stinton otoliths. After splitting the cores vertically in two (1973) described otoliths from grab samples off halves, they were investigated for various geo Massachusetts. More recently Gaemers (1977, technical and geological properties (Vorren et al. 1978a, 1979a and 1979b) has described recent 1978, 1983, 1984). One-half of the core was di and Late Quaternary otoliths from the North Sea vided into 10 cm long units and sieved. The > l Basin. mm grade was searched for otoliths and other We report here results from a shelf area off fish remains. Altogether, 239 otoliths and two northern Norway (Fig. lA) which has a well fish teeth were found. Identifications were made dated Late Quaternary stratigraphy (Vorren et by comparing them with the senior author's re al. 1983, 1984, Hald & Vorren 1984, Thomsen & cent otolith collection, and with fossil otoliths in Vorren, in prep.). We conclude that otoliths are the collection of the Rijksmuseum van Geologie a useful stratigraphic tool and that they give en Mineralogie, Leiden, the Netherlands, where additional information about the palea-environ the present material has been deposited (RGM ment. registrati on numbers 176. 716-176.863). The cores investigated were recovered from a trough, Malangsdjupet, crossing the shelf (Fig. lB). The trough is 451 deep in the inner reaches, Stratigraphy whilst the threshold at the shelf break is about 260 m deep. The watermasses in this area are The stratigraphy of the cores from Malangsdju dominated by Atlantic water in the Norwegian pet and adjacent shelf areas (Fig. 2) has been Current (salinity about 35% or more) and the described by Vorren et al. (1983, 1984). Details less saline overlying, seaward thinning wedge of of the Holocene stratigraphy based on foramini water in the Norwegian Coastal Current. Tem fera and macrofossils are given in Hald & Vorren peratures fluctuate between 4 and 12oc through (1984) and Thomsen & Vorren (in prep.) respec out the year. tively. Otoliths were found in units tD, tC, tB, tA and the Fugløybanken Sand comprising the dA, dB and sA units on Fig. 2. 188 P. A. M. Gaemers & T. O. Vorren NORSK GEOLOGISK TIDSSKRIFT 3 (1985)
Fig. l. A: Location map with indication of area studied. B: Bathymetric map of the Malangsdjupet with the station location. The encircled number gives numbers of cores raised from each station.
Units tD and tC are very dark grey glaciomar ings to comprise the time span 13,000 to 10,000 ine pebbly and sandy pelites, deposited in an B. P. The tB unit ( = the Børingan Pelite of Hald iceberg environment. A recent dating from the & Vorren 1984) is an olive grey mud containing lower part of unit tD gave 13,740 ± 400 B. P. between 15 and 35% carbonate. It was deposited (AA-400). Unit tC is shown by several 14C-dat- 10,000 to 7,800 years ago. During the last 7,800
years unit tA ( = Andfjorden Sand) was deposit ed. This unit is composed of a sandy calcareous TROUGH > 300m , > ---DEEP BANK > 150m > SHALLOW BANK (30-50% carbonate) mud having an olive colour. -- ("'<:,: a. t:: The Fugløybanken Sand ( = units dA + dB + "' �l; ,.. � �9 .. . . sA), mostly occurring in the shallower areas, is a se .n; :c: · Holocene sandy gravel, produced by winnowing. ·� �� IMUO�CRA.VEL The investigatedcores show the following stra dO� '(_". •· - tigraphy (Table 1). Cores from the outer stations ��l(;._. (1, 2, 5 and 55) comprise units ti, tF, tE, tD, tC, [MUO�GRAVEL a hiatus, and on top Fugløybanken Sand. The Pleistocene diamictons in station l could not LEG END easily be teferred to the described stratigraphy;
0- CLAY AND SILT probably they are older Pleistocene sediments. E D SAND Cores from the stations 56, 57, 58 and 60 com � PEBBLES & COBBLES prise units tA, tB and do occasionally penetrate � CALCAREOUS SEDIMENT into unit tC (all four cores from station 56, one �r� § LAMINATED CLAY from 57 and two from 60). At the relatively < o 0 SAND LENSE shallow station 61 (287-257 m) Fugløybanken � BIOTURBATION Sand was overlying older Pleistocene deposits. []] SHELLS IN SITU The one core from station 62 showed a heavily w SHELL FRAGMENTS disturbed sequence of tB and tA sediments. The disturbances may possibly be the result of sub marine mass movement. Fig. 2. Composite general stratigraphy of the upper sediment layer in the troughs, the deep banks and the shallow banks on the shelf off Troms arid West Finnmark. After Vorren et al. (1984). NORSK GEOLOGISK TIDSSKRIIT 3 (1985) Otolith stratigraphy, Weichselian-Ho/ocene, Ma/angsdjupet 189
Table l. Investigated cores; sampling depth, total core Iength in cm and thickness of the individual lithostratigraphic units in cm.
FS = Fugløybanken Sand and P = undifferentiated Pleistocene. Units where otoliths were found are shaded.
CORE T H l C K N E S S O F U N l T S (cm) CORE DEPTH LENGTH FS tA tB tC tD tE tF ti p No m cm
1-4 280 125 114 1-5 302 25 20
2-3 312 211 22 20 106 2-6 308 159 2-8 311 304 20 20 79 2-9 312 335 20 18 77 2-10 313 332 25 14 43
5-1 316 318 141 78 20 12 58
55-3 348 112 : i$o 37
56-1 348 392 56-2 350 365 56-3 352 357 56-4 351 394
57-1 435 352 5 7-3 411 367 7
58-1 443 339 58-2 448 373 58-3 442 345 58-4 440 329
60-1 377 179 i�Q •.. 17 60-2 376 348 tro· ·. i�·< ifl3·. 60-3 422 264 iio s 3 111 60-4 426 168 . 168 > ..
61-1 287 101 96 61-2 286 74 56 61-3 257 64 54
62-2 304 223
Thanatocoenosis versus biocoenosis species represented still live in the sea surround ing northern Norway or in the immediate neigh Otoliths from eleven fish species were identified, bourhood. According to Hognestad & Vader eight of which belong to the codfish family (Ta (1979), abundant present-day species in the wa bles 2 and 4). For illustrations of most species see ters off northern Norway are: Gadus morhua, Plates 1-3. The most common species is the blue Melanogrammus aeglefinus, Micromestius pou whiting, Micromesistius poutassou (50.6% ), fol tassou, Neocolliolus esmarki, Pollachius virens, lowed by the Norway pout, Neocolliolus esmarki Sebastes marinus and Glyptocephalus cynoglos
(30.5% ) , and cod, Gadus morhua (5.4% ). All sus. The following species are fairly common: P. A. M. Gaemers & T. O. Vorren NORSK GEOLOGISK TIDSSKR!Ff 3 (1985)
Table 2. Total numbers and percentages of the different otoliths found, and their occurrence in the various lithostratigraphic units. Core 62-2 is shown separate! y as it was impossible to distinguish unit tA and tB in this core.
F. Sand Unit A Unit B ST.62-2 Unit C Unit D Total No. % No. % No. % (A+B) % (and E?)
M. poutassou 40 54.1 65 66.3 4 20.- lO 24.4 2 121 N. esmarki 17 23.- 14 14.3 15 75.- 27 65.9 73 G. morhua 5 6.8 6 6.1 5.- l 2.4 13 M. aeglefinus 3 4.1 2 2.1 5 Boreogadus sp. 3 4 P. virens 2 2.7 l. O 2.4 4 G. thori 1.3 l M. merlangus l. O l Gadinarum sp. (otoliths) 4 5.4 6 6.1 2. 4 11 Gadinarum sp. (teeth) 2 2 N. kroeyeri 1.3 l Sebastes sp. 1.3 2 2.1 3 G. cynoglossus l l. O 2.4 2 TOTAL 74 98 20 41 5 3 241
Table 3. Size, age, and maturity of fish represented by fossil otoliths in Malangsdjupet. Fish lengths for each species calculated from otolith lengths. Ages of fish inferred from lengths, not counted by year rings in the fossil otoliths. Sexual maturity: juv. = juvenile, ad. = adult.
Species fish length estimated age sexual family in cm in years maturity
Notoscopelus kroeyeri (Malm, 1861) ca. 10 l or 2 juv. Myctophidae Gadus morhua Linnaeus, 1758 65-11 Notoscopelus kroeyeri, Gadiculus thori and Mer One would, however, expect that otoliths of langius merlangus. Boreogadus saida has only the very smallest fishes are most abundant, but been found occasionally in north Norwegian wa this is not the case; fish smaller than 7 cm are ters, but it is abundant in the seas north of Russia nearly completely lacking. This can be explained and other Arctic waters. by more rapid dissolution of smaller otoliths in Most otoliths are from juvenile fish less than gastric acid of predators or in sediment pore one to two years old, and from specimens smaller water - because of a less favourable surface/ than 15 cm. Only a few specimens come from fish volume ratio and higher percentages of protein larger than 20 cm (a survey is given in Table 3). and less aragonite- than in later formed layers of This can be explained by the high mortality rate larger and older otoliths (the diminishing per for most fish species. Thus the large numbers of centage of organic material from the centre to small otoliths in the bottom sediments reflect to a wards the rim can be observed in Degens et al. high degree the biological situation that young (1969, Fig. 3), where the organic material is visi fish outnumber the older. It necessarily follows ble as dark bands). that most otoliths found in bottom sediments Due to the high juvenile mortality and the come from fish that were eaten by larger ani solution problem, small fish species having rela mals. tively large otoliths will be better represented in NORSK GEOLOGISK TIDSSKRIFT 3 (1985) Otolith stratigraphy, Weichselian-Ho/ocene, Ma/angsdjupet 191 the fossil assemblage than large species and spe o � OTOLITH eies with relatively small otoliths (Gaemers 1977, :I: o 0.. ZONES 1978a). Owing to this, the percentages of the Q <{ >( o:: different fish species in the fossil record are usu w Ul 0.. S2Ul z w CD o ." ally not a reliable reflection of the original per �t::: N z g. ." l :::. ." :::. Ul o::Z o "' :::. ." g. centages of former living faunas. This is also true o:: l-=> w N "' ., "' � <{ Ul (!) � � � :::. � � "' for the Malangsdjupet otoliths. The cod family, w o <{ w "' � � � .l:! ... >- :I: w :::!; � � ., ... � l l- z "' � � "' � .... ., � ::: which is most frequent, possesses relatively large '!!u - � � � !:i "' � !:i � "" _J ::J otoliths in comparison to many other fish fam � � � "' � Cl.: � l..:i � l ilies, thus it may be concluded that several other l l l l l families were more common in the area during l l l l l l Late Weichselian and Holocene times than can l l l l l l l be concluded from the fossil record. l l M. l l tA l l l (A.ndfjOI'dtn fJOIIf(]S- l l l Sond) "' sou l :::. l l 5 l l l """ l l l Otolith stratigraphy <::: l l l � l l l ...... l l l A dose correlation between the litho- and bio - l l l �� l stratigraphy has been shown by Vorren et al. tB l (BtfrlnQon � N. l (1984), Hald & Vorren (1984) and Thomsen & Pelil•) esmarki l l Vorren (in prep.). When considering the occur lO f--- � � l l l rence of the otoliths within the investigated litho l te Boreo- stratigraphy, a clear pattern emerges (Table 2). gadus ? ' l rare sp. l ' No otoliths were found in units older than unit 13 r--::-- l 'rother l tD (or tE). Units tC and tD (or tE) are the only r--1Q_ ----- l common common units bearing otoliths of polar cod (Boreogadus ? sp). We establish the Boreogadus sp. Acme . Fig. 3. Generalized frequency and stratigraphic range of fish Zone, and define it by the dominance of Boreo fossils in the deeper part of Malangsdjupet. For definition of gadus sp. (Hedberg 1976). This acme-zone seems the M. merlangus Lineage-zone, see Gaemers (1978b). to coincide with the lithostratigraphic units tC and tD (or tE). The term range-zone is avoided here because this zone certainly does not cover the entire stratigraphic range of Boreogadus sp. Paleoenvironmental implications Unit tB has a dominance of Neocolliolus es Boreogadus sp. Acme-Zone marki (75%) and we define the N. esmarki Acme-Zone for strata where this otolith is domi In addition to the four Boreogadus sp. otoliths, nant. The data at hand indicate that this corre two teeth of Gadinarum sp. and two otoliths sponds to the tB-unit. from M. poutassou occur in this zone. The Bor A third biozone is defined by the dominance of eogadus otoliths may belong to B. saida or B. Micromesistius poutassou (mean: 61% ). This M. agilis, probably the latter (see Appendix: Se leet poutassou Acme-Zone seems to correspond to ed Systematics). Boreogadus saida prefers to live the Fugløybanken Sand and the unit tA. under sea ice or at its edge. It is a coastal fish, It should be pointed out that the frequencies of but it also occurs around icebergs and among otoliths are rather low in the Late Weichselian floating ice far from land (Jensen 1905, Svetovi and Early Holocene sediments. A larger data set dov 1962). B. agilis is only known from a small may show that the acme-zone boundaries deviate number of specimens west of Greenland (Sveto somewhat from the lithostratigraphic bound vidov 1962), and lives in the same environment aries. A generalized picture of the relation be as B. saida. This environmental description fits tween litho-, chrono- and otolith-stratigraphy in well with earlier interpretation of the environ the deeper part of Malangsdjupet is shown in ment during tE to tC-time, i.e., about 15,000 to Fig. 3. 10,000 years ago (Vorren et al. 1984). The find All the fossil zones defined belong to the Mer ings of M. poutassou in unit tD may indicate langius merlangus Lineage-Zone of the Gadidae periods with somewhat warmer water. However, otolith zonation of Gaemers (1978b). it should be noted that reworked fossils occur 192 P. A. M. Gaemers & T. O. Vorren NORSK GEOLOGISK TIDSSKRIFT 3 (1985) Table 4. Distribution of otoliths in the cores; numbers of otoliths per sample and per species. Lithostratigraphic units are given before the vertical line of each core; their boundaries are indicated with a dashed line. FS = Fugløybanken Sand and P undifferentiated Pleistocene. 55-3 1-4 1-5 2-3 2-6 2-8 2-9 2-10 FS FS •• ' F8 2 FS FS 7 1 1 0 _ , , 1 , 1 -- 10 -- �-�r . " IC f�--!_ 304 ID 21 tC ID p 332 1 :: [ ..F F 31f . IC IC 211 tEM�r.. 1 112 :: [ 335 o. 10 � � " " " " g� " " o �� o �� .. � �� ·� � 5 121 �� [ -" �i �l � lj'g � �! 131 o 57-1 57-3 58-1 58-2 58-3 58-4 11 20 30 30 30 40 :� 50 : ! 2 60 l 89 70 [l 70 lO BO 80 90 lO 95 100 .. 105 110 110 111 120 120 120 130 127 130 130 tA ... 140 1-40 140 A A tA t l 150 157 180 111 t 1 lA [ 2 112 [ 170 180 2 180 [ 190 200 [ 200 210 210 1 1 220 220 [ 223 l 233 230 23!5 240 --�- 240 245 255 255 lB 205 285 lB 275 27 8 271 282 2 18 : � 290 18 [ 280 � ( 300 300 : 373 305 : �329 lB 387 310 tB 315 352 339 345 NORSK GEOLOGISK TIDSSKRIFT 3 (1985) Otolith stratigraphy, Weichselian-Holocene, Malangsdjupet 193 5-1 56-1 56-2 56-3 56-4 61-1 61-2 61-3 2 1 10 F810 lO l l 2 IA· = 11 IC 20 --• • a., 20 l FS·t· 10 p � p F tA 7< •• 318 302 ··r.-· 80 10 80 18 18 18 9. 357 •o• �å. "� .., �� " c "-" 325 Q.o- tC . " 335 o � ! "'"' "' 385 � � " �n,.. :;:j � &. �" � o o ,. :z" "' 60-1 60-2 60-3 60-4 62-2 10 2 3 20 11 18 30 21 28 37 •o •o 38 .6 .3 <1 3 • •o lA 50 51 01 58 55 l 80 60 2 • 87 88 85 70 lA 10 2 78 75 80 lA 80 lA lA 81 85 90 90 100 28. 112 115 120 125 lO 130 �:� [ 18 168 157 179 187 188 [ lB 196 223 � �:;:j 280 �i� IC a� !l 270 =i.::ici TABLE 4 boundary between lithostratiSJraphic units 10 sample with otoliths; the numbers befare the line are 20 1[ 2 depths in cm below sea-bottom, the numbers behind the bar are the numbers of otoliths ln the sample � length of core in cm below·sea-bottom when not drawn 352 to scale l length of core drawn to scale 194 P. A. M. Gaemers & T. O. Vorren NORSK GEOLOGISK TIDSSKRIFT 3 (1985) relatively frequently in this unit (Thomsen & 1000 m isobath in water with temperatures not Vorren, in prep.) as also demonstrated by radio lower than 8--9°C and a salinity not below carbon datings (Vorren et al. 1984). The poor 36.2%o (Svetovidov 1962). The large number of state of preservation of the otoliths of M. poutas otoliths of this fish in the Malangsdjupet samples sou (both are worn and broken) in comparison proves that it is also abundant in areas where with those of Boreogadus, and the difference in water depths are less than 1000 m. This agrees colour of the two species, make it much more with earlier findings of many M. poutassou oto likely that the M. poutassou otoliths have been liths in the Norwegian Trough (Gaemers 1978a). reworked. The occurrence of Notoscopelus kroeyeri also agrees well with an oceanic environment. It is a lantern fish having a mesopelagic mode of life. It Neocolliolus esmarki Acme-Zone is a characteristic element in the deeper associ Represents the time span 10,000-7,800 YBP. A ation off southern Norway together with the change to warmer water is indicated by the disap dominant M. poutassou (Gaemers 1978a). pearance of B. saida and appearance of N. es Gjøsaeter (1981) studied the mode of life and marki together with M. poutassou and G. mor ecology of N. kroeyeri west of southern Norway, hua. N. esmarki is an extremely common small and north and west of Scotland and Ireland. He gadoid in northern European waters (Wheeler could find neither specimens with ripening go 1978). It lives dose to the bottom, prefers a nads nor young fish or larvae of this species, so smooth sand-mud substrate and is most common he suggested that the observed population was offshore in depths of 80-300 m (Muus 1966, Sve expatriated. Spawning probably takes place far tovidov 1973). It spawns in deep water over the ther away above deeper parts of the Atlantic. edge of the continental shelf (Wheeler 1978). The more frequent occurrence of otoliths of this The N. esmarki Acme-Zone is found in cores lantern fish in sediments off southern Norway recovered from depths between 448 and 350 m. suggests that it is more common there than in the This is deeper than the maximum abundance of north, where it seems to be dose to its northern living fish of this species as recorded in the litera boundary. ture (300 m). It is also deeper than the transition Glyptocephalus cynoglossus is another repre from a shallower assemblage dominated by N. sentative of deeper water. According to Wheeler esmarki to a deeper one dominated by M. pou (1978), it lives at depths of 300-900 m and more; tassou found in recent and sub-recent otolith ma it appears to be confined to mud and mud-sand terial in the Norwegian Trough at a depth of ca bottoms. Wheeler mentions that this species is 290 m (Gaemers 1978a). especially common in the deep fjords of Norway and the Faeroe Islands. The presence of otoliths from G. morhua, M. Micromesistius poutassou Acme-Zone aeglefinus, P. virens, G. thori and Sebastes sp. This zone succeeds the N. esmarki zone in the agrees with the horizontal and vertical distribu deeper cores (unit A) and represents the time tion of the living species. The rarity of otoliths of span 7,800 YBP to present. In the shallower G. thori in samples investigated is striking; its areas, the M. poutassou Acme-Zone corresponds otoliths are common off southern Norway to the Fugløybanken Sand of Holocene age. (Gaemers 1978a). The rarity in the Malangsdju The M. poutassou Acme-Zone has the lar- . pet sediments must reflect a much rarer occur gest otolith diversity. This is partly because of rence of this species off northern Norway. The the larger volume of sediments investigated from only rather unexpected element is one juvenile the tA-unit, and partly it is due to less dilution by otolith of M. merlangus found at a depth of 426 detrital sediments in the tA-unit. m (station 60). This species is a shallow water The blue whiting, M. poutassou, is a rather fish which is most abundant between 30 and 100 small gadoid which occurs in large shoals in Eu m, and exceptionally goes down to 200 m ropean waters. It is an oceanic fish having a (Wheeler 1978). The one specimen may be a pelagic mode of life; it is most abundant 100-300 stray individual - much shallower waters are m below the surface in areas where the ocean is dose to station 60. Moreover, the species does 1000 m deep or more, but is also found in the not only live dose to the bottom, but also in uppermost layers of the sea (Wheeler 1978, Sve intermediate and upper water layers (Svetovidov tovidov 1973). Spawning takes place near the 1962). Another explanation may be that the fish NORSK GEOLOGISK TIDSSKRIFT 3 (1985) Otolith stratigraphy, Weichselian-Holocene, Malangsdjupet 195 was eaten in shallower water by a larger fish indicating a boreal, but more oceanic environ which excreted the otolith in deeper water. ment, Looking at the depth distribution of otoliths in - Three acme-zones can be established which the M. poutassou Acme-Zone a slight difference probably will be useful for the whole Norwe can be observed between the shallower and the gian continental shelf and some adjoining shelf deeper areas. Fugløybanken Sand, representing areas. station� between 348 m and 257 m, has higher Acknowledgements. - Part of this work was financed by the frequencies of N. esmarki and less of M. poutas Norwegian Research Council for Science and Humanities sou than unit tA representing stations between (Grant D-48-23-03), and by the stipend of the Niels Stcnscn 448 m and 348 m. This can be explained by the Foundation (Amsterdam, the Netherlands) to the senior au larger numbers of living N. esmarki above shal thor. The crew on F/F Johan Ruud cooperated with core sampling. M. Berntsen and M. Raste (Univ. Tromsø) assisted lower sea floors. In spite of its mixed strati with the laboratory work. Jeff Zwinakis (Woods Hole) made graphy, this trend is also seen in core 62-2 from the drawings, R. l. W. Dijkman (Museum, Lciden) made 304 m having an overall higher content of N. Table 4, and W. A. M. Devile and J. Verhoeven (Museum, esmarki (Table 2). The data from the M. poutas Leiden) made the photographs. We offer our sincere thanks to all these persons and institutions. sou Acme-Zone in Malangsdjupet agree with Manuscript received November 1984 data from the sea off south em Norway, where a dominance shift between N. esmarki and M. poutassou occurs at about 290 m water depth References (Gaemers 1978a). Degens, E. T., Deuser, W. G. & Haedrich, R. L. 1969: When explaining the fauna! change from the Molecular structure and composition of fish otoliths. Marine N. esmarki to the M. poutassou Acme-Zone, it Biol. 2, 105-113. should be noted that this change seems to occur Gaemers, P. A. M. 1976: New gadiform otoliths from the Tertiary of the North Sea Basin and a revision of some fossil concurrently with a registered change in the and recent species. Leidse geo/. Meded. 49, 507-537. benthonic and planktonic foraminifera fauna. Gaemers, P. A. M. 1977: Recente en jong-kwartaire visresten The change in the foraminifera fauna was ex van het Long Forties gebied, noordelijkc Noordzcc. Meded. plained by Hald & Vorren (1984) as being caused Werkgr. Tert. Kwart. Geo/. 14, 21-40. Gaemers, P. A. M. 1978a: Late Quaternary and Recent oto by the water masses becoming less turbid, warm liths from the seas around southern Norway. Meded. er, more saline and more nutrient rich. Werkgr. Tert. Kwart. Geo/. 15, 101-117. M. poutassou is a more oceanic fish than N. Gaemers, P. A. M. 1978b: A biozonation based on Gadidae esmarki. The fauna! change in the Holocene de otoliths for the northwest European younger Cenozoic, with the description of some new species and genera. Meded. posits of Malangsdjupet thus indicates that the Werkgr. Tert. Kwar!. Geo/. 15, 141-161. water masses became more oceanic in the later Gaemers, P. A. M. 1979a: Een interessante otolietenfauna part of the Holocene. afkomstig uit de Noordzee, 20 kilometer westelijk van Sche veningen. Zeepaard 39, 31-46. Gaemers, P. A. M. 1979b: Aanvullend otolictenmatcriaal af komstig uit de Noordzee, 20 kilometer westelijk van Sche Conclusions veningen. Zeepaard 39, 59--62. Gjøsaeter, J. 1981: Life history of the myctophid fish Notosco Analysis of fish fossils (otoliths and teeth) in pelus e/ongatus kroeyeri from the northcast Atlantic. Fisk Dir. Skr. Ser. HavUnders. 17, 133-152. Late Weichselian and Holocene sediments from Hald, M. & Vorren, T. O. 1984: Modem and Holocene fora Malangsdjupet shows that: minifera and sediments on the continental shelf off Troms, - Most otoliths are derived from juvenile speci North Norway. Boreas. mens, Hedberg, H. D. (ed.) 1976: International Stratigraphic Guide. A Guide to Stratigraphic C/assification, Terminology, and - Small fishes with relatively large otoliths are Procedure. John Wiley & Sons Inc., New York, London, best preserved in the fossil record, Sydney, Toronto, xxii + 200 p. - Polar cod (Boreogadus sp.) was the dominat Hognestad, P.T. & Vader, W. 1979: Saltvannsfiskene i Nord ing species from about 15,000 or 14,000 to Norge. Tromsø Mus. Rapportser., Naturvitensk. 6, 1-74. Jensen, A. S. 1905: On fish-otoliths in the bottom-deposits of 10,000 YBP, indicating an arctic iceberg/sea the sea. l. Otoliths of the Gadus spccies deposited in the ice environment, polar deep. Meddelelser Komm. HavUnders. , Ser. Fiskeri l, - Norway pout (Neocolliolus esmarki) was the 1-14. dominant species in the Early Holocene, indi Kelly, G. F. & Wolf, R. S. 1959: Age and growth of the redfish (Sebastes marinus) in the Gulf of Maine. Fish. Bull., U. S. 60 cating a boreal environment, (156), iv + 31 p. - After 7800 YBP blue whiting (Micromesistius Muus, B. J. 1966: Zeevissengids. Zeevissen en zeevisserij in poutassou) became the dominant species, also Noordwest-Europa. Elsevier, Amsterdam/Brussel, 244 p. 196 P. A.M. Gaemers & T. O. Vorren NORSK GEOLOGISK TIDSSKRIFT 3 (1985) Schmidt, J. 1914: Gadiculus argenteus and Gadiculus thori. Gadiculus thori J. Schmidt, 1914 Mindeskr. Japetus Steenstrups Føds. 14, 1-10. Svetovidov, A. N. 1962: Fauna of the U.S.S.R., Fishes, Vol. 9, Biologists often consider G. thori a subspecies of + no. 4, Gadiformes. Israel Progr. sei. Trans/at., iv 304 p. G. argenteus, but adult otoliths of these species (translat. from Russian, 1948). have a different shape. Also the larvae of these Svetovidov, A. N. 1973: Gadidae./n: Hureau, J. C. & Monod, Th (eds. ): Checklist of the fishes of the northeastern Atlantic species have distinctly different pigmentation and of the Mediterranean, Part I. Unesco, Paris, 303-320. (Schmidt, 1914) what is considered an important Thomsen, E. H. & Vorren, T. O. (in prep.): Late Quaternary species character by biologists studying young macrofaunal paleoecology and stratigraphy in shelf sedi fish. For illustrations of otoliths of G. thori (as ments off northern Norway. Trout, G. C. 1961: The otoliths of group-0 Sebastes mente/la well as of Notoscopelus kroeyeri) see Gaemers Travin. I.C.N.A.F. Spee. Publ. 3, 2%-299. (1978a). Vorren, T. 0., Strass, I. F. & Lind-Hansen, 0.-W. 1978: Late Quaternary sediments and stratigraphy on the continental shelf off Troms and West Finnmark, northern Norway. Qua Boreogadus sp. ternary Research 10, 340-365. Vorren, T. 0., Hald, M., Edvardsen, M & Lind-Hansen, 0. A comparison could be made with recent otoliths W., 1983: Glacigenic sediments and sedimentary environ of several individuals of B. saida from the Alas ments on continental shelves; general principles with a case kan part of the Bering Sea, the Atlantic off study from the Norwegian shelf. In: Ehlers, J. (ed.): G/acial deposits in Northern Europe. A. A. Balkema, Rotterdam. Newfoundland and from off northern Norway. Vorren, T. 0., Hald, M. & Thomsen, E. 1984: Quaternary All these specimens are however clearly more sediments and environments on the continental shelf off slender in shape than the fossil otoliths. The northern Norway. Marine Geo/. 57, 29 p. shapes of the sulcus and the colliculi agree well Wheeler, A. 1978: Key to the Fishes of northern Europe. A Guide to the Identification of more than 350 Species. Freder with the recent B. saida otoliths, ensuring the ick Warne Ltd., London, xix + 380 p. generic identification. Probably the fossil otoliths Wigley, R. L. & Stinton, F. C. 1973: Distribution of macro belong to the other recent species, B. agilis, scopic remains of recent animals from marine sediments off which seems to be rare nowadays. The otoliths of Massachusetts. Fish. Bull., U.S. 71, 1-40. this species are still unknown, unfortunately. Photographs of a well-preserved juvenile otolith from the Weichselian of the Island of Arnøy are Appendix given on Plate 3, Fig. 2, because the juvenile Selected Systematics specimens from the Malangsdjupet are too poor ly preserved. Gadus Morhua Linnaeus, 1758 Compared with recent specimens of the same Sebastes sp. sizes from the southern North Sea these otoliths are stronger knobbed and thinner; moreover the Juvenile otoliths from S. marinus and S. mente/la postdorsal angle has been stronger developed appear to be very similar when the illustrations giving a more oval outline of the otoliths. The of Kelly & Wolf (1959, Figs. 2 and 4) and Trout recent otoliths have a more slender, pear-shaped (1961, pl. 2) are compared. Unfortunately not appearance with a more or less gradually taper the same small sizes of recent Sebastes otoliths ing cauda! part and a more obliquely running are available as comparison for the fossil oto rostral rim. The most likely explanation for these liths. A species identification therefore is difficult differences is that the Malangsdjupet specimens at the moment. It is most likely that the fossil belonged to another population than those from otoliths belong to S. marinus because this is by the southern North Sea. far the most common redfish species in the area. PLATE l All specimens from the Andfjorden Sand (unit tA). Enlargement of all specimens x 10. All a-numbers are media) views, b numbers lateral views, c-numbers ventral views, and d-numbers dorsal views. Fig. la-d. Neocolliolus esmarki (Nilsson, 1855), station 60-1, 130-140 cm, RGM 176.807. Fig. 2a-d. Neoco//io/us esmarki (Nilsson, 1855), station 58-2, 200-210 cm, RGM 176.798. Fig. 3a-d. Neocol/io/us esmarki (Nilsson, 1855), station 60-3, 76-87 cm, RGM 176.809. Fig. 4a-d. Gadus morhua Linnaeus, 1758, station 60-4, 60-70 cm, RGM 176.829. Fig. 5a-d. Gadus morhua Linnaeus, 1758, station 60-2, 27-37 cm, RGM 176.827. Hg. 6a-c. Sebastes sp., station 60-4, 89--100 cm, RGM 176.858. NORSK GEOLOGISK TIDSSKRIFT 3 (1985) Otolith stratigraphy, Weichselian-Ho/ocene, Ma/angsdjupet 197 198 P. A. M. Gaemers & T. O. Vorren NORSK GEOLOGISK TIDSSKRIFT 3 (1985) PLATE 2 All specimens from the Andfjorden Sand (unit tA). Enlargement of all specimens (except Fig. 2) x 10. All a-numbers are media! views, b-numbers lateral views, c-numbers ventral views, and d-numbers dorsal views. Fig. la-d. Micromesistius. poutassou (Risso, 1826), station 60-1, 30-40 cm, RGM 176.761. Fig 2a-b. Micromesistius poutassou (Risso,1826), station 60-3,56-66 cm, RGM 176.770, x 9.3. Fig. 3a-b. Micromesistiuspoutassou (Risso, 1826), station 62-2,55-65 cm, RGM 176.783. Fig. 4a-b. Melanogrammus aeglefinus (Linnaeus, 1758), station 58-1, 20-30 cm. RGM 176.833. Fig. 5a-c. Merlangius merlangus (Linnaeus, 1758), station 60-4, 112-120 cm,RGM 176.842. NORSK GEOLOGISK TIDSSKRIFT 3 (1985) Oto/ith stratigraphy, Weichse/ian-Holocene, Malangsdjupet 199 PLATE 3 Enlargement of all specimens (except Fig. 2) x 10. All a-numbers are media) views, b-numbers lateral views, c-numbers ventral views, and d-numbers dorsal views. Fig. l a-d. Boreogadus sp., Late Weichselian, unit tC, station 2-9, 80-90 cm. RGM 176.843. Fig. 2a-d. Boreogadus sp., Weichselian, fossiliferous lill, Leirhda, Island of Arnøy (N of Tromsø), sample no. 10-79/KA, coll. Gaemers, leg. Vorren, x 9.5. Fig. 3a-d. Po//achius virens (Linnaeus, 1758), Fugløybanken Sand, station 61-3, 0-10 cm. RGM 176.839. Fig. 4a-d. Melanogram mus aeg/efinus (Linnaeus, 1758), Andfjorden Sand, station 60-2, 17-27 cm, RGM 176.834. 14- Geologisk Tidsskr. 3/85