BULLETIN OF MARINE SCIENCE, 71(2): 883–892, 2002
MIDWATER CEPHALOPODS IN THE WESTERN NORTH ATLANTIC OCEAN OFF NOVA SCOTIA
M. Vecchione and G. Pohle
ABSTRACT The midwater fauna off Nova Scotia was sampled with large pelagic trawls over bot- tom depths of 169–4800 m on seven cruises between August 1986 and June 1989. We identified, counted, and measured mantle length (ML) of all 3661 cephalopods collected on these cruises. These specimens comprised about 63 species in 28 families. The ten most abundant families were (in rank order) Ommastrephidae, Enoploteuthidae, Pyroteuthidae, Histioteuthidae, Brachioteuthidae, Cranchiidae, Mastigoteuthidae, Octopoteuthidae, Onychoteuthidae, and Alloposidae. Although Illex illecebrosus was the most numerous species (1156 specimens in 54 samples), Abraliopsis hoylei (679 in 90, respectively), Histioteuthis reversa (164 in 72), and Pterygioteuthis gemmata (327 in 69) were collected more frequently. Large squids collected here include 3 cranchiids, Teuthowenia megalops (max. ML = 370 mm), Galiteuthis armata (308 mm), and Taonius pavo (300 mm), as well as mature female Gonatus fabricii (275 mm) and Illex illecebrosus (235 mm). Among the 47 species with <10 specimens, noteworthy examples include Chiroteuthis joubini, Chiroteuthis capensis, Joubiniteuthis portieri, Histioteuthis meleagroteuthis, Pholidoteuthis boschmai, Lepidoteuthis grimaldi, Heteroteuthis dispar, Vampyroteuthis infernalis, and Stauroteuthis syrtensis.
An important initial step in understanding biological diversity is to determine what lives where. Although published reports of distribution can sometimes provide some in- formation, such reports must be considered with care (Vecchione et al., 2000). Examina- tion of a large collection of the organisms in question is therefore a valuable opportunity to document diversity. A series of cruises was conducted by the Department of Fisheries and Oceans (DFO), Canada, to survey the slope-water fauna off Nova Scotia. The primary gear type used for these surveys was a large, standard midwater trawl. The main target of the survey was the midwater fish fauna and its relationship with the complex local environment, where the Gulf Stream and entrained water from the Sargasso Sea mixes with slope water and the deep Labrador Current. We have identified all of the cephalopods collected on these cruises to characterize the diversity of cephalopods in this region. We report here the species collected on these cruises and present comments on taxonomy, relative abundance and distribution. The present work is part of a broader study of western Atlantic cephalopods (Vecchione, 2001; Vecchione and Galbraith, 2001; Vecchione and Roper, 1991; Vecchione et al., 2001).
MATERIALS AND METHODS
Seven cruises of the Canadian Fisheries RV NEEDLER were conducted between August 1986 and June 1989 to sample midwater nekton, especially fishes. Trawling was conducted offshore of the 200 m isobath, south and southeast of Nova Scotia (Figs. 1–3). The primary sampling gear was the International Gadid Young Pelagic Trawl (IGYPT), a standard large midwater trawl. Other gear included otter trawls for epibenthic sampling and Tucker trawls for discrete-depth midwater sam- pling. Detailed hydrographic observations were collected as well. All cephalopods were retained
883 884 BULLETIN OF MARINE SCIENCE, VOL. 71, NO. 2, 2002
Figure 1. Examples of species commonly encountered over the upper continental slope. (Upper panel) Histioteuthis reversa; (Lower panel) Brachioteuthis sp. (beanii?). Figure includes captures for all seven cruises combined. Dashed lines indicate 20 m and 200 m isobaths. Size of crosses proportional to number of specimens in catch. from all samples and have been archived at the Atlantic Reference Centre (ARC) at Huntsman Marine Science Laboratory. We identified and counted all cephalopods for curation into the perma- nent collections at ARC. We also measured dorsal mantle length (ML) on all specimens except those too damaged to measure. VECCHIONE AND POHLE: CANADIAN ATLANTIC MIDWATER CEPHALOPODS 885
Figure 2. Examples of species commonly encountered farther offshore than those in Figure 1. (Upper panel) Abralia redfieldi; (Lower panel) Enoploteuthis anapsis. See Figure 1 for explanation.
RESULTS
Table 1 summarizes the identifications of the 3661 cephalopods collected during these cruises, along with the maximum ML and maximum relative abundance (number of speci- mens per sample) for each species. Identifications comprised approximately 63 species in 28 families. The ten most abundant families were (in rank order) Ommastrephidae, Enoploteuthidae, Pyroteuthidae, Histioteuthidae, Brachioteuthidae, Cranchiidae, Mastigoteuthidae, Octopoteuthidae, Onychoteuthidae, and Alloposidae. Illex illecebrosus was by far the most numerous species overall and comprised the most specimens in a 886 BULLETIN OF MARINE SCIENCE, VOL. 71, NO. 2, 2002
Figure 3. Examples of species collected essentially throughout the sampled area. (Upper panel) Mastigoteuthis magna; (Lower panel) Octopoteuthis megaptera. See Figure 1 for explanation. single sample. However, several other species were collected more frequently (i.e., found in more samples) than I. illecebrosus. These frequently collected species included the enoploteuthid Abraliopsis hoylei, the histioteuthid Histioteuthis reversa, and the pyroteuthid Pterygioteuthis gemmata. Patterns of dominance among these species varied among cruises (Table 2). Whereas I. illecebrosus was almost twice as numerous as the next most abundant species, A. hoylei, the latter ranked first in relative abundance on three of the seven cruises. Large specimens collected here include 3 cranchiids, Teuthowenia megalops (max. ML = 370 mm), Galiteuthis armata (308 mm), and Taonius pavo (300 mm), as well as mature female Gonatus fabricii (275 mm) and I. illecebrosus (235 mm). The pelagic octopod VECCHIONE AND POHLE: CANADIAN ATLANTIC MIDWATER CEPHALOPODS 887
Table 1. Summary of cephalopod collection. Z: bottom depth at collecting station.
Tfaxon N o N of N of Maximum Minimum Maximum specimens specimens samples N per bottom Z ML (mm) per family per species per sample species A6lloposidae 6 Haliphron atlanticus 676 3738,30 010 A4ncistrocheiridae 3 Ancistrocheirus alessandrini 304 2410,55 48 A1rgonautidae Argonauta s1110p. 47,20 B3athyteuthidae Bathyteuthis abyssicola 33114,93 95 B4olitaenidae Eledonella pygmaea 33116,93 93 Japetella diaphana 11145,60 01 B3rachioteuthidae 19 Brachioteuthis (beanii?3) 119 5429176 6 C5hiroteuthidae 3 Chiroteuthis capensis 22130,30 012 Chiroteuthis joubini 11140,80 05 Chiroteuthis veranyi 371 2229,30 013 Chiroteuthis s11p. C1htenopterygidae 1 Chtenopteryx sicula 17401 24,70 5 C5ranchiidae 14 Cranchia scabra 157 1314,80 06 Galiteuthis armata 11138,80 030 Helicocranchia papillata 22134,60 05 Leachia atlantica 31331,00 06 Leachia lemur 11146,50 05 Leachia s44p. Megalocranchia s6520p. 35,60 8 Taonius pavo 146 12705 930 Teuthowenia megalops 942 4917409 37 U32nidentified C1ycloteuthidae? U1110nidentified 4,50 E7noploteuthidae 86 Abralia redfieldi 489 1837,70 03 Abralia veranyi 19241 13,55 4 Abralia s53p. Abraliopsis atlantica 5941 3049,20 2 Abraliopsis hoylei 6079 926011,80 4 Enoploteuthis anapsis 512 152044,20 5 Enoploteuthis leptura 43248,50 02 Enoploteuthis s21p. U4nidentified 12 888 BULLETIN OF MARINE SCIENCE, VOL. 71, NO. 2, 2002
Table 1. Continued.
Tfaxon N o N of N of Maximum Minimum Maximum specimens specimens samples N per bottom Z ML (mm) per family per species per sample species G0onatidae 3 Gonatus fabricii 340 22359 127 H2istioteuthidae 20 Histioteuthis arcturi 44137,30 04 Histioteuthis bonnellii 87213,80 02 Histioteuthis corona corona 54227,70 05 Histioteuthis meleagroteuthis 32247,60 03 Histioteuthis reversa 1264 7913361 9 Histioteuthis s8p. 141 J1oubiniteuthidae Joubiniteuthis portieri 11145,00 05 L2epidoteuthidae Lepidoteuthis grimaldi 22145,00 06 L1ycoteuthidae 2 Selenoteuthis scintillans 211 1730,10 03 M9astigoteuthidae 11 Mastigoteuthis agassizi 21239,70 04 Mastigoteuthis flammea?863015,30 6 Mastigoteuthis hjorti 77130,50 012 Mastigoteuthis magna 884 4615,05 015 Mastigoteuthis s8p. 141 O3ctopodidae Bathypolypus arcticus 111887 02 Octopus defilippi 11140,50 01 Unidentified paralarva 11146,40 0 O5ctopoteuthidae 9 Octopoteuthis (1110danae?) 20,10 6 Octopoteuthis megaptera 816 5615,80 010 Octopoteuthis rugosa 11111,20 06 Octopoteuthis sicula 11244,80 06 Octopoteuthis s53p. Taningia danae 11149,60 07 O1cythoidae? Ocythoe tuberculata?11104,00 O4mmastrephidae 123 Illex illecebrosus 14,156 50276 459 23 Ommastrephes bartramii 22139,80 09 Ornithoteuthis antillarum 620 112015,28 12 Sthenoteuthis pteropus 16705 38,70 8 U11nidentified O2nychoteuthidae 7 Ancistroteuthis lichtensteini 18301 10,80 6 Onychoteuthis cf. banksii 548 341010,80 5 VECCHIONE AND POHLE: CANADIAN ATLANTIC MIDWATER CEPHALOPODS 889
Table 1. Continued.
Tfaxon N o N of N of Maximum Minimum Maximum specimens specimens samples N per bottom Z ML (mm) per family per species per sample species Onykia carriboea 22131,80 02 u11nidentified P4holidoteuthidae Pholidoteuthis boschmai 44115,93 94 P2yroteuthidae 46 Pterygioteuthis gemmata 3927 622019,90 2 Pyroteuthis margaritifera 1235 481028,70 3 S8epiolidae 2 Heteroteuthis dispar 11119,28 01 Stoloteuthis leucoptera 2417 23341 2 S2tauroteuthidae Stauroteuthis syrtensis 22125,50 06 T1hysanoteuthidae Thysanoteuthis rhombus 11146,50 03 V3ampyroteuthidae Vampyroteuthis infernalis 33119,70 02 f1amily undetermined 2 u1nidentified 202
2s8 families 3.,661 specimen ca. 63 spp Haliphron atlanticus should also be included among the large cephalopods, but its gelati- nous consistency resulted in large specimens being badly fragmented and unmeasurable. Among the 47 species with <10 specimens, noteworthy examples include Chiroteuthis joubini, Chiroteuthis capensis, Joubiniteuthis portieri, Histioteuthis meleagroteuthis, Pholidoteuthis boschmai, Lepidoteuthis grimaldi, Heteroteuthis dispar, Vampyroteuthis infernalis, and Stauroteuthis syrtensis. Whereas some of these species are common else- where (H. dispar, V. infernalis), many are rarely collected anywhere. As we were still adding to the species list with the identifications from the last few samples we examined, it seems likely that additional sampling would discover other rare species in the study area. A collection this large allows some general distribution patterns to become apparent. For instance, some species, such as H. reversa (Fig. 1A) and Brachioteuthis sp. (B. beanii?; Fig. 1B) were collected more frequently over the upper continental slope. The distribution of other species was concentrated farther offshore (e.g., Abralia redfieldi, Fig. 2A; Enoploteuthis anapsis, Fig 2B). Species such as Mastigoteuthis magna (Fig. 3A) and Octopoteuthis megaptera (Fig. 3B) were found essentially throughout the sampled area. The minimum bottom depth over which each species was collected is presented in Table 1. 890 BULLETIN OF MARINE SCIENCE, VOL. 71, NO. 2, 2002
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DISCUSSION
The number of species we found is not exact because numerous identification prob- lems were encountered. For example, two morphotypes of Brachioteuthis were tenta- tively separated, differing in skin texture and morphometrics. Whether these were two separate species and, if so, what names should be applied to each morphotype cannot be determined with confidence until the family Brachioteuthidae has been thoroughly re- viewed on a worldwide basis. Similar problems apply to the cranchiid genera Leachia and Megalocranchia. Some species cannot be identified confidently unless the specimen is in adequate con- dition. If, for instance, the tail of an O. megaptera is abraded, as commonly occurs in net collection, the specimen will key out to O. danae if some of the tail remains, or to O. sicula if the tail is missing entirely (Nesis, 1987). In some such cases it is likely that the specimens that could be identified only to genus level belong to the numerically domi- nant species in that genus. For example, identification of H. reversa depends on locating a short marginal row of small photophores on the ventral arms. This row is often abraded or difficult to distinguish in net-collected specimens, compromising confident identifica- tions. Alternative identifications for such specimens include H. eltaninae and H. corona corona. The former is a South Atlantic species, but the presence of other species thought to be from the South Atlantic, such as C. capensis, raises the question of whether some such species are actually bipolar in distribution. Mature male H. eltaninae can be distin- guished from H. reversa based on spermatophore morphology (Voss et al. 1998). In addi- tion to photophore patterns, which are easily damaged by collecting nets, H. corona co- rona differs from H. reversa in the sculpture of the dorsal pad of the funnel organ, a subtle and sometimes difficult character to assess. It is likely, however, that most of the speci- mens identified here as Histioteuthis sp. are actually H. reversa. Histioteuthis corona corona appears to have darker color and thicker skin than H. reversa. This collection included mature female H. reversa, which formerly were referred to H. elongata. On small Onychoteuthis banksii, the intestinal light organs are not easily seen. Some of these specimens may be Ancistroteuthis lichtensteini, a species which is more common in the western North Atlantic than we expected based on literature reports. On larger speci- mens, the latter species has relatively longer arms than O. banksii. Dorsal exposure of the gladius in O. banksii, but not in A. lichtensteini, seems to be a good character down to about 10 mm ML. Small Ornithoteuthis antillarum likewise can easily be confused with Ommastrephes bartramii, but the multiple visceral photophores are obvious by 40 mm ML. Mature female Gonatus fabricii lose their tentacles and the lateral rows of suckers on the arms. The arm hooks are deeply embedded in the arms and the muscle tissue is gelatinous. As a result, such specimens could be mistaken for Chaunoteuthis (= mature Onychoteuthis). Fisheries surveys usually concentrate on abundant species, which have either economic or ecological importance. The few specimens of rarely collected species caught in such projects tell little about the ecology of the species. However, including rare species in reports from multiple projects will eventually allow enough published information to accumulate for ecological patterns to be discerned. Additionally, such reports may inform systematists where material important for their studies is archived. We recommend that researchers continue to devote attention to the unusual as well as the abundant. 892 BULLETIN OF MARINE SCIENCE, VOL. 71, NO. 2, 2002
ACKNOWLEDGMENTS
R. Haliday of DFO conducted this sampling program and encouraged us to identify the cephalo- pods and to publish the results. The Huntsman Marine Science Centre partially supported two trips by the first author to collaborate with the second on identification and curation of the collection. K. Sulak, formerly of ARC, initially invited M.V. to participate in this project. M.V. also thanks R. Gibbons of the NMFS National Systematics Lab for assistance in preparation of the oral presenta- tion of these data at the CIAC2000 meeting. We thank N. Voss and an anonymous reviewer for their comments on a draft of this paper.
LITERATURE CITED
Nesis, K. N. 1987. Cephalopods of the world; squids, cuttlefishes, octopuses, and allies. TFH Pub- lications. Neptune, New Jersey. 351 p. Vecchione, M. 2001. Cephalopods of the continental slope east of the United States. Am. Fish. Soc. Symp. 25: 153–160. ______and J. Galbraith. 2001. Cephalopod species captured by deepwater exploratory fish- ing off New England. Fish. Res. 51: 385–391. ______, M. Mickevich, K. Fauchald, B. Collette, A. Williams, T. Munroe and R. Young. 2000. Importance of assessing taxonomic adequacy in determining fishing effects on marine biodiversity. ICES J. Mar. Sci. 57: 677–681. ______and C. F. E. Roper. 1991. Cephalopods observed from submersibles in the western North Atlantic. Bull. Mar. Sci. 49: 433–445. ______, C. F. E. Roper, M. J. Sweeney and C. C. Lu. 2001. Distribution of paralarval cepha- lopods in the western North Atlantic Ocean with observations on paralarval development. NOAA/ Tech. Rpt. NMFS 152: 1–54. Voss, N. A., K. N. Nesis and P. G. Rodhouse. 1998. Family Histioteuthidae. Smithson. Contrib. Zool. 586: 293–372.
ADDRESSES: (M.V.) NMFS National Systematics Lab., National Museum of Natural History, Washing- ton, D.C. 20560. (G.P.) Atlantic Reference Centre, Huntsman Marine Science Lab., St. Andrews, NB, E5B 2L7 Canada.