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Pelagic food of Coryphaenoides armatus, a deep benthic rattail
Re,arch, 1974,Vol.21, pp. 739 to 744.PergamonPrnu.Printedin GreatBritain.
Pelagic food of Coryphaenoides armatus, a deep benthic rattail* R. L. HAnDlUCH~I"and N. R. HENDERSON,: (Received 26 October 1973; in revised form 1 February 1974; accepted 8 February 1974)
Al~tract---Stomach eontc~atsfrom 79 specimens of the macrourid Coryphaenoides armatus trawled at depths below 2600 m in Hudson Canyon fell into three major categories: benthic animals, pelagic animals, and items of terrestrial or neritie origin. Pelagic cephalopods and fishes,especially Chauliodus and Serrivomer spp., were important components of the diet, particularly of the larger fish, and it is suggested that C. armatus may move off the bottom into mid-depths to feed. The findings of vegetables, insect and bird remains, and strips of rubber and plastic in the stomachs indicate that this species is extremely generalized in its feeding habits. Its activities are important in transferring food e~ergy from mid-depths over the deep-ocean floor, where rather large food items must be originally dispersed as finer particles. INTRODUCTION THE SECONDleg o f R.V. Chain Cruise 111 was devoted primarily to bottom trawling in Hudson Canyon (ca. 39°30'N, 72°20'W). Major interests were to determine the composition and distribution of epibenthic fauna in the canyon at continental slope depths and to collect material useful in understanding how a submarine canyon influences deep-ocean communities. Since canyons may funnel organic material into the deep sea (RowE, 1972), food habit studies were planned to determine trophic structure within such communities. Sampling was concentrated between 200 and 2000 m, but a few deeper samples were collected, including two bottom trawls to 2600 and 2760 m. The composition of these two catches was similar and was quite different from that of shallower collections. The fish catch, 138 specimens weighing 27 kg, was dominated by the macrourid Coryphaenoides (Nematonurus) armatus (Hector 1875). The stomachs of about 2/3 of the C. armatus specimens were not everted, an unusual situation in deep-trawled benthic fishes, and provided important material for study of food habits. Examination o f this material revealed that a major portion of the diet of this species comes not from i t s benthic environs, but from the deep mesopelagic and bathypelagic regions. Our long-term goal is to understand the overall ecology of deep-ocean communities. We report here the feeding o f C. armatus in relation to such understanding and provide some observations on its general biology. Collections that included Coryphaenoides armatus during R.V. Chain Cruise I 11 were Trawl 252, 39°11 'N, 71°31 'W to 39°18'N, 71°15' W, 2 March, 1973, estimated time on bottom ca. 0205 to 0335 h, 2580 to 2626 m, 40-ft Gulf of Mexico shrimp trawl (l-in. mesh), and Trawl 253, 39°01 'N, 71°10'W to 39°02'N, 70°44'W, 2 March,.1973, estimated time on bottom ca. 1045 to 1215 h, 2736 to 2780 m, 40-ft Gulf of Mexico *Contribution No. 3191 from the Woods Hole Oceanographic Institution. "['Woods Hole Oceanographic Institution, Woods Hole, Massachusetts 02543, U.S.A. ~Wellesley College, Wellesley, Massachusetts 02181, U.S.A. 739
740
R . L . HAI~DRiCHand N. R. HI~NDERSON
i°1400 la00
X
m 1O~'
w . t&7.t-~tts.tl,.~.d-
llO0,
x
16o
lio
lio
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lio
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LEHOTH (Sn to anal fin) in MILLIMETERS
Fig. 1. Length(snout to anal fin origin, in ram) frequenciesand the length-weightrelationship for Coryphaenoides armatus, based on 79 specimens from Trawl 252 and 253, R.V. Chain Cruise 111. shrimp trawl (1-in. mesh). Trawl 252 captured 39 C. armatus 240 to 520 mm total length (TL) and Trawl 253 took 44 C. armatus 208 to 620 mm TL. The specimens, other than four that were frozen, were preserved with the rest of the catch in 10% buffered formalin and were sorted out and transferred to 70 % ethanol several weeks later in the laboratory. Lengths and weights were measured from whole specimens; stomachs were then removed for individual examination. GENERAL BIOLOGICAL OBSERVATIONS
The length frequencies and the length-weight relationship for the Coryphaenoides armatus specimens are shown in Fig. 1. Since the tips of the tails were sometimes missing, we measured the distance from the snout to the origin of the anal fin. This may be 28 to 38% of the TL (MARSrIALLand IWAM(rrO, 1973). No specimen was ripe. Most appeared to be either young or immature females. Of the 79 examined, only 18 were considered males. Other fish species taken in Trawls 252 and 253 were the synaphobranchid Histiobranchus bathybius (Giinther 1877) (1 specimen, 695 mm TL, 636 g), the halosaurid Halosauropsis macrochir (Gtinther 1878) (3 specimens, 600-650 mm TL, 710 g), the notacanthid Polyacanthonotus africanus (Gilchrist and yon Bonde 1924) (1 specimen, 403 mm TL, 74 g), the alepocephalid Bathytroctes koefoedi (Parr 1951) [1 specimen, 340 mm standard length (SL), 432 g], the bathypteroid Benthosaurua grallator (Goode and Bean 1897) ( 1 specimen, 132 mm SL, 10 g), the eretmophorid Antimora rostrata (CrUnther 1878) (41 specimens, 259 to 490 mm SL, 22,312 g), and the
Pelagic food of Coryphaenoides armatus, a deep benthic rattail
741
macrourids Coryphaenoides brevibarbis (Goode and Bean 1896) (5 specimens, 220 to 350 mm TL, 445 g), and Coryphaenoides leptolepis (Gtinther 1877) (2 specimens, 336 to 450 mm TL, 447 g). Coryphaenoides armatus (Hector 1875) was represented by 83 specimens 208 to 620 ram TL, weighing 22,043 g. Of these species, the Histiobranchus, the Bathytroctes, the Benthosaurus, and the three Coryphaenoides were not taken in any of the shallower trawls. The information-function diversity H [ = -- Y.p log • p, SI~r~or~ and WEAVER(1963)] of this assemblage is 1.07 on numbers and 0.97 on weight (biomass). Both values are low, and reflect the marked dominance by C. armatus and Antimora. The effective opening of the 40-ft trawl is about 8 m when towed at speeds of 2 to 3 knots* (BtJLLISand Ctna~nt~s, 1963). An hour's trawling thus covers some 32,000 m ~. The catch rate for Trawls 252 and 253 of 15.9 kg h -1 suggests that each square meter in this region supports about 0.5 g of fish. FOOD HABITS
The major categories of food eaten by Coryphaenoides armatus are listed in Table 1 according to the size of the fish in which each was found. We have excluded from consideration freshly ingested prey that could have been eaten in the net. Broadly speaking, food items fall into three different classes--benthic animals, pelagic animals, and items of terrestrial or neritic origin. Of the crustaceans, amphipods (73 specimens) were the most abundant, followed by isopods (72), cumaceans (62), tanaids (19), decapods (15), copepods (12), mysids (4), and euphausiids (3). Most of these belonged to essentially benthic taxa (i.e. amphipods in the Caprellidea, Liljeborgiidae, Phoxocephalidae, Lysianassidae, and Aoridae; isopods in the Arcturidae, Maerostylidae, Ilyarachnidae, Storthyngura, Eurycope, and Syneurycope; decapods in the Penaeidae). The mysids (Boreomysis sp.) could be either benthic or pelagic, but the euphausiids Nematoscelis megalops and Bentheuphausia amblyops, the decapods in the Sergestidae, Oplophorus, and crab megalops are certainly meso- or bathypelagic. Benthic polychaetes (21 specimens) belonged to the families Maldanidae, Glyceridae, Nereidae, Arabellidae, and the cosmopolitan eurybathie species Terebellides stroemi. The single specimen of the Pycnogonida belonged to Callipallene ac/Kq.
Cephalopods formed an important part of the diet of Coryphaenoides armatus, particularly of the larger specimens. No whole animals were found but generally only portions of tentacle or a beak. Identifications using the keys of CLAgKE (1962) were difficult. The major families represented seemed to be Enoploteuthidae, Histioteuthidae, and Gonatidae. All are primarily pelagic. The two fishes encountered most often in the stomach contents were the stomiatoid Chauliodus (10 specimens) and the eel Serrivomer (4). Twenty specimens of other fishes were found. These included the head of an approximately 110-ram Rondeletia bicolor, a 70-ram Howella brodiei, and various portions of Eurypharynx pelecanoides, Stomias sp., .4rgyropelecus sp., Echiostoma sp., Ceratoscopelus sp., and Melanostomiatidae. Not identified were numerous assorted bones and bits of vertebral columns. All fishes were either meso- or bathypelagic. Plant material occurred in at least nine stomachs. Bits of Sargassum were found on three occasions; thesehave also been found in the stomachs of ophiuroids from similar depths (ScHoENERand RowE, 1970). More surprising was the find, in one fish, of thetwo *1 knot •ffi 0"51 m s-a,
742
R . L . I'IAEDRICH a n d N . R . HENDERSON
Table 1.
Food items found in Coryphaenoides armatus by size (snout to anal fin) offish. Entries are number of stomachs in which an item occurred. 69-99 mm
100-139 m m
140-179 n u n
180-229 m m
Mysidacea Polychaeta
4 -1 2 2 3 2 1 3
12 4 14 6 6 3 7 -7
Pycnogonida
--
--
Copepoda Euphausiacea Dccapoda Crustacean parts Ccphalopoda
1 -----
4 1 3 4 2
20 3 13 3 3 1 7 I 6 1 3 2 4 7 16
5 1 2 1 1 -1 ---1 --2 5
Stomachs with food Empty stomachs Evcrted stomachs Cumacea Tanaidacea Isopoda Amphipoda
Chauliodus
--
1
6
Serrivomer
--
1
3
O t h e r fishes
--
5
10
Sargasaum
--
2
--
Things from surface
--
2
2 --
3 1
7
2
neritic algae Porphyra umbilicus and Rhodymenia palmata. Terrestrial plant material included potatoes, onions, cabbage, celery, beans, airborne seeds, and unidentified vascular plant material. Terrestrial animals were represented by the prothorax and one elytrum of a tenebrionid beetle, the head of a pentatomid bug (Acrosternum ?), and, on three occasions, the feathers of birds. Some strips of rubber and the plastic liner of a jar cap were also found. The data of Table l suggest that smaller Coryphaenoides armatus feed almost entirely on benthic animals. As the fish grows, there is a shift in emphasis to more pelagic creatures, especially other fishes and cephalopods. This same situation was found in C. armatus taken off Oregon (PEARCYand AMBLER, 1974). By volume (or weight), the contribution from benthic animals was far overshadowed by that from much larger pelagic fishes and cephalopods. DISCUSSION
Study of the food habits of Coryphaenoides armatus leads us to conclude that this cosmopolitan ( I w A M O T O and STEIN, 1974) rattail derives a major portion of its diet not from the bottom but from the overlying midwaters of the deep ocean. PEARCY and AMBLER(1974) explore the several possible explanations whereby assumed bottomliving rattails might obtain pelagic prey. Essentially, oither the prey must approach the bottom, through the normal course of its activities in the midwater or by dying and falling through the water column, or the predator must move off the bottom to feed in the pelagic zone. So little is known of the vertical distribution of animals below 1000 m that it is difficult to decide which event is the more likely. Certain of the fishes (i.e. Eurypharynx, Rondeletia, Serrivomer) from the stomachs of C. armatus are
Pelagic food of Coryphaenoides armatus, a deep benthic rattail
743
bathypelagic and might naturally occur near bottom at 2600 m. Chauliodus, however, a common prey species, is thought to be more mesopelagic. Neither we nor our colleagues G. T. Rowe and J. E. Craddock have ever observed this species, either dead or alive, on the bottom at 1800 m on numerous dives in the Deep-Sea Research Vehicle Alvin. Unpublished data on file at the Woods Hole Oceanographic Institution tend to support HAFFNT.g'S(1952) contention that Chauliodus has its daytime center of abundance shallower than 1800 m off southern New England, but the data are not unequivocal. Feeding on Chauliodus may involve some vertical migration by C. armatuY. Chauliodus itself migrates into the upper 800 m of the water column at night, where it feeds on invertebrates and small fishes (MORROW, 1964). These two species may thus provide examples of energy transfer into the deep sea by the active means envisaged by VXNO~RADOV(1962) in his 'ladder of migrations'. In discussing the maintenance of diversity in the deep sea, DAYTONand HV~SL~g (1972) cited several examples of generalized feeding by predaceous forms. This, they felt, was contrary to the predictions of SA~'DE~' (1968) stability-time hypothesis wherein high diversity in the deep sea should result, at least in part, from increased food specialization by community members and thus avoidance of competitive overlap. Coryphaenoides armatus must be considered a generalist in its feeding habits, for it apparently will eat whatever it encounters, including objects with no food value whatsoever. This fact, and the finding of material clearly from the surface, such as the vegetables and bird fragments, is in keeping with the prediction (DAYTONand HESSL~t, 1972) that deep-sea fish should be extreme food generalists capable of locating and consuming large and rapidly settling material. Since large C. armatus feed mostly on midwater animals, however, the influence of this fish on the bottom must be primarily as a disperser of food particles rather than as a predator involved in the diversitymaintaining scheme proposed by Dayton and Hessler. Because C. arrnatus is so widespread and because it may form a considerable fraction of the fish population at depths below 2500 m (GREY, 1956), its activities must be taken account of in discussions of deep-ocean ecology. Acknowledgements--We extend our thanks to R. H. BACKU$,N. B. MARSHALL,W. B. P~AitC"lt,and G. T. Rowe for their reading of the manuscript. The following people gave generously of their time in the identification of stomach contents: S. H. B ~ w t x ~ (plants), S. P. GARNER(isopods and amphipods), D. C. JtmgJ1,vs (decapods and euphausiids), P. T. PoLt.Om (worms), and J. E. ~ D O a C (otoliths). To all we are grateful. This work was supported by National Science Foundation grant GA 31235 X, a grant to the Department of Biological Sciences, Wellesley College, from the E. I. du Pont de Nemours Corporation, and a work-study grant from Wellesley College.
REFERENCES
BULLI$H.R., JR. and R. C u ~ w s , JR. (1963) Another look at the royal red shrimp resource. Proceedings of the Gulf and Caribbean Fisheries Institute, 15th annual session, pp. 9-12. CLARKE M. R. (1962) The identification of cephalopod "beaks" and the relationship between beak size and total body weight. Bulletin of the British Museum (Natural History), 8(1), 419--480. DAYTON P. K. and R. R. HESSLER (1972) Role of biological disturbance in maintaining diversity in the deep sea. Deep-Sea Research, 19, 199-208. GREY M. (1956) The distribution o f fishes found below a depth of 2000 meters. Fieldiana Zoology, 36(2), 75-337. H ~ R. E. (1952) Zoogeography of the bathypelagic fish Chauliodus. Systematic Zoology, 1(3), 112-133.
744
R. L. HA~PaCHand N. R. l'Im~mtSON
I w ~ q ' o T. and D. L. STERN(1974) A systematic review of the rattall ~ (Maorouridae: Gadiformes) from Oregon and adjacent waters. Occasional Papers of the California Academy of Sciences, No. 111, 1-79. MAaSHALL N. B. and T. IWAMOTO(1973) Family Macrouridae. In: Fishes of the western North Atlantic. Memoir, Sears Foundationfor Marine Research, No. 1, part 6, pp. 496-662. MoRRow J. E., JR. (1964) Family Chauliodontidae. In: Fishes of the western North Atlantic. Memoir, Sears Foundationfor Marine Research, No. 1, part 4, pp. 274-289. P s ~ c ~ W. G. and J. W. AMSLeR (1974) Food habits of deep-sea macrourid fishes off the Oregon coast. Deep.Sea Research, 21, 745-759. Rowe G. T. (1972) The exploration of submarine canyons and their benthic faunal assemblages. Proceedings of the Royal Society of Edinburgh (B), 73(17), 159-169. S ~ H. L. (1968) Marine benthic diversity: a comparative study. The American Naturalist, le~(925), 243-282. SCHO~_~ A. and G. T. ROWE(1970) Pelagic Sargassum and its presence among the deep-sea benthos. Deep-Sea Research, 17, 923-935. SHANNONC. E. and W. WEAVER(1963) The mathematical theory of communication, University of Illinois Press, 117 pp. VINOORADOVM. E. (1962) Feeding of the deep-sea zooplankton. Rapports et proc~s-verbaux des rdunions. Conseilpermanent pour rexploration de la met, 153(18), 114-120.
Pelagic food of Coryphaenoides armatus, a deep benthic rattail* R. L. HAnDlUCH~I"and N. R. HENDERSON,: (Received 26 October 1973; in revised form 1 February 1974; accepted 8 February 1974)
Al~tract---Stomach eontc~atsfrom 79 specimens of the macrourid Coryphaenoides armatus trawled at depths below 2600 m in Hudson Canyon fell into three major categories: benthic animals, pelagic animals, and items of terrestrial or neritie origin. Pelagic cephalopods and fishes,especially Chauliodus and Serrivomer spp., were important components of the diet, particularly of the larger fish, and it is suggested that C. armatus may move off the bottom into mid-depths to feed. The findings of vegetables, insect and bird remains, and strips of rubber and plastic in the stomachs indicate that this species is extremely generalized in its feeding habits. Its activities are important in transferring food e~ergy from mid-depths over the deep-ocean floor, where rather large food items must be originally dispersed as finer particles. INTRODUCTION THE SECONDleg o f R.V. Chain Cruise 111 was devoted primarily to bottom trawling in Hudson Canyon (ca. 39°30'N, 72°20'W). Major interests were to determine the composition and distribution of epibenthic fauna in the canyon at continental slope depths and to collect material useful in understanding how a submarine canyon influences deep-ocean communities. Since canyons may funnel organic material into the deep sea (RowE, 1972), food habit studies were planned to determine trophic structure within such communities. Sampling was concentrated between 200 and 2000 m, but a few deeper samples were collected, including two bottom trawls to 2600 and 2760 m. The composition of these two catches was similar and was quite different from that of shallower collections. The fish catch, 138 specimens weighing 27 kg, was dominated by the macrourid Coryphaenoides (Nematonurus) armatus (Hector 1875). The stomachs of about 2/3 of the C. armatus specimens were not everted, an unusual situation in deep-trawled benthic fishes, and provided important material for study of food habits. Examination o f this material revealed that a major portion of the diet of this species comes not from i t s benthic environs, but from the deep mesopelagic and bathypelagic regions. Our long-term goal is to understand the overall ecology of deep-ocean communities. We report here the feeding o f C. armatus in relation to such understanding and provide some observations on its general biology. Collections that included Coryphaenoides armatus during R.V. Chain Cruise I 11 were Trawl 252, 39°11 'N, 71°31 'W to 39°18'N, 71°15' W, 2 March, 1973, estimated time on bottom ca. 0205 to 0335 h, 2580 to 2626 m, 40-ft Gulf of Mexico shrimp trawl (l-in. mesh), and Trawl 253, 39°01 'N, 71°10'W to 39°02'N, 70°44'W, 2 March,.1973, estimated time on bottom ca. 1045 to 1215 h, 2736 to 2780 m, 40-ft Gulf of Mexico *Contribution No. 3191 from the Woods Hole Oceanographic Institution. "['Woods Hole Oceanographic Institution, Woods Hole, Massachusetts 02543, U.S.A. ~Wellesley College, Wellesley, Massachusetts 02181, U.S.A. 739
740
R . L . HAI~DRiCHand N. R. HI~NDERSON
i°1400 la00
X
m 1O~'
w . t&7.t-~tts.tl,.~.d-
llO0,
x
16o
lio
lio
leo
lio
~o
2~
~o
LEHOTH (Sn to anal fin) in MILLIMETERS
Fig. 1. Length(snout to anal fin origin, in ram) frequenciesand the length-weightrelationship for Coryphaenoides armatus, based on 79 specimens from Trawl 252 and 253, R.V. Chain Cruise 111. shrimp trawl (1-in. mesh). Trawl 252 captured 39 C. armatus 240 to 520 mm total length (TL) and Trawl 253 took 44 C. armatus 208 to 620 mm TL. The specimens, other than four that were frozen, were preserved with the rest of the catch in 10% buffered formalin and were sorted out and transferred to 70 % ethanol several weeks later in the laboratory. Lengths and weights were measured from whole specimens; stomachs were then removed for individual examination. GENERAL BIOLOGICAL OBSERVATIONS
The length frequencies and the length-weight relationship for the Coryphaenoides armatus specimens are shown in Fig. 1. Since the tips of the tails were sometimes missing, we measured the distance from the snout to the origin of the anal fin. This may be 28 to 38% of the TL (MARSrIALLand IWAM(rrO, 1973). No specimen was ripe. Most appeared to be either young or immature females. Of the 79 examined, only 18 were considered males. Other fish species taken in Trawls 252 and 253 were the synaphobranchid Histiobranchus bathybius (Giinther 1877) (1 specimen, 695 mm TL, 636 g), the halosaurid Halosauropsis macrochir (Gtinther 1878) (3 specimens, 600-650 mm TL, 710 g), the notacanthid Polyacanthonotus africanus (Gilchrist and yon Bonde 1924) (1 specimen, 403 mm TL, 74 g), the alepocephalid Bathytroctes koefoedi (Parr 1951) [1 specimen, 340 mm standard length (SL), 432 g], the bathypteroid Benthosaurua grallator (Goode and Bean 1897) ( 1 specimen, 132 mm SL, 10 g), the eretmophorid Antimora rostrata (CrUnther 1878) (41 specimens, 259 to 490 mm SL, 22,312 g), and the
Pelagic food of Coryphaenoides armatus, a deep benthic rattail
741
macrourids Coryphaenoides brevibarbis (Goode and Bean 1896) (5 specimens, 220 to 350 mm TL, 445 g), and Coryphaenoides leptolepis (Gtinther 1877) (2 specimens, 336 to 450 mm TL, 447 g). Coryphaenoides armatus (Hector 1875) was represented by 83 specimens 208 to 620 ram TL, weighing 22,043 g. Of these species, the Histiobranchus, the Bathytroctes, the Benthosaurus, and the three Coryphaenoides were not taken in any of the shallower trawls. The information-function diversity H [ = -- Y.p log • p, SI~r~or~ and WEAVER(1963)] of this assemblage is 1.07 on numbers and 0.97 on weight (biomass). Both values are low, and reflect the marked dominance by C. armatus and Antimora. The effective opening of the 40-ft trawl is about 8 m when towed at speeds of 2 to 3 knots* (BtJLLISand Ctna~nt~s, 1963). An hour's trawling thus covers some 32,000 m ~. The catch rate for Trawls 252 and 253 of 15.9 kg h -1 suggests that each square meter in this region supports about 0.5 g of fish. FOOD HABITS
The major categories of food eaten by Coryphaenoides armatus are listed in Table 1 according to the size of the fish in which each was found. We have excluded from consideration freshly ingested prey that could have been eaten in the net. Broadly speaking, food items fall into three different classes--benthic animals, pelagic animals, and items of terrestrial or neritic origin. Of the crustaceans, amphipods (73 specimens) were the most abundant, followed by isopods (72), cumaceans (62), tanaids (19), decapods (15), copepods (12), mysids (4), and euphausiids (3). Most of these belonged to essentially benthic taxa (i.e. amphipods in the Caprellidea, Liljeborgiidae, Phoxocephalidae, Lysianassidae, and Aoridae; isopods in the Arcturidae, Maerostylidae, Ilyarachnidae, Storthyngura, Eurycope, and Syneurycope; decapods in the Penaeidae). The mysids (Boreomysis sp.) could be either benthic or pelagic, but the euphausiids Nematoscelis megalops and Bentheuphausia amblyops, the decapods in the Sergestidae, Oplophorus, and crab megalops are certainly meso- or bathypelagic. Benthic polychaetes (21 specimens) belonged to the families Maldanidae, Glyceridae, Nereidae, Arabellidae, and the cosmopolitan eurybathie species Terebellides stroemi. The single specimen of the Pycnogonida belonged to Callipallene ac/Kq.
Cephalopods formed an important part of the diet of Coryphaenoides armatus, particularly of the larger specimens. No whole animals were found but generally only portions of tentacle or a beak. Identifications using the keys of CLAgKE (1962) were difficult. The major families represented seemed to be Enoploteuthidae, Histioteuthidae, and Gonatidae. All are primarily pelagic. The two fishes encountered most often in the stomach contents were the stomiatoid Chauliodus (10 specimens) and the eel Serrivomer (4). Twenty specimens of other fishes were found. These included the head of an approximately 110-ram Rondeletia bicolor, a 70-ram Howella brodiei, and various portions of Eurypharynx pelecanoides, Stomias sp., .4rgyropelecus sp., Echiostoma sp., Ceratoscopelus sp., and Melanostomiatidae. Not identified were numerous assorted bones and bits of vertebral columns. All fishes were either meso- or bathypelagic. Plant material occurred in at least nine stomachs. Bits of Sargassum were found on three occasions; thesehave also been found in the stomachs of ophiuroids from similar depths (ScHoENERand RowE, 1970). More surprising was the find, in one fish, of thetwo *1 knot •ffi 0"51 m s-a,
742
R . L . I'IAEDRICH a n d N . R . HENDERSON
Table 1.
Food items found in Coryphaenoides armatus by size (snout to anal fin) offish. Entries are number of stomachs in which an item occurred. 69-99 mm
100-139 m m
140-179 n u n
180-229 m m
Mysidacea Polychaeta
4 -1 2 2 3 2 1 3
12 4 14 6 6 3 7 -7
Pycnogonida
--
--
Copepoda Euphausiacea Dccapoda Crustacean parts Ccphalopoda
1 -----
4 1 3 4 2
20 3 13 3 3 1 7 I 6 1 3 2 4 7 16
5 1 2 1 1 -1 ---1 --2 5
Stomachs with food Empty stomachs Evcrted stomachs Cumacea Tanaidacea Isopoda Amphipoda
Chauliodus
--
1
6
Serrivomer
--
1
3
O t h e r fishes
--
5
10
Sargasaum
--
2
--
Things from surface
--
2
2 --
3 1
7
2
neritic algae Porphyra umbilicus and Rhodymenia palmata. Terrestrial plant material included potatoes, onions, cabbage, celery, beans, airborne seeds, and unidentified vascular plant material. Terrestrial animals were represented by the prothorax and one elytrum of a tenebrionid beetle, the head of a pentatomid bug (Acrosternum ?), and, on three occasions, the feathers of birds. Some strips of rubber and the plastic liner of a jar cap were also found. The data of Table l suggest that smaller Coryphaenoides armatus feed almost entirely on benthic animals. As the fish grows, there is a shift in emphasis to more pelagic creatures, especially other fishes and cephalopods. This same situation was found in C. armatus taken off Oregon (PEARCYand AMBLER, 1974). By volume (or weight), the contribution from benthic animals was far overshadowed by that from much larger pelagic fishes and cephalopods. DISCUSSION
Study of the food habits of Coryphaenoides armatus leads us to conclude that this cosmopolitan ( I w A M O T O and STEIN, 1974) rattail derives a major portion of its diet not from the bottom but from the overlying midwaters of the deep ocean. PEARCY and AMBLER(1974) explore the several possible explanations whereby assumed bottomliving rattails might obtain pelagic prey. Essentially, oither the prey must approach the bottom, through the normal course of its activities in the midwater or by dying and falling through the water column, or the predator must move off the bottom to feed in the pelagic zone. So little is known of the vertical distribution of animals below 1000 m that it is difficult to decide which event is the more likely. Certain of the fishes (i.e. Eurypharynx, Rondeletia, Serrivomer) from the stomachs of C. armatus are
Pelagic food of Coryphaenoides armatus, a deep benthic rattail
743
bathypelagic and might naturally occur near bottom at 2600 m. Chauliodus, however, a common prey species, is thought to be more mesopelagic. Neither we nor our colleagues G. T. Rowe and J. E. Craddock have ever observed this species, either dead or alive, on the bottom at 1800 m on numerous dives in the Deep-Sea Research Vehicle Alvin. Unpublished data on file at the Woods Hole Oceanographic Institution tend to support HAFFNT.g'S(1952) contention that Chauliodus has its daytime center of abundance shallower than 1800 m off southern New England, but the data are not unequivocal. Feeding on Chauliodus may involve some vertical migration by C. armatuY. Chauliodus itself migrates into the upper 800 m of the water column at night, where it feeds on invertebrates and small fishes (MORROW, 1964). These two species may thus provide examples of energy transfer into the deep sea by the active means envisaged by VXNO~RADOV(1962) in his 'ladder of migrations'. In discussing the maintenance of diversity in the deep sea, DAYTONand HV~SL~g (1972) cited several examples of generalized feeding by predaceous forms. This, they felt, was contrary to the predictions of SA~'DE~' (1968) stability-time hypothesis wherein high diversity in the deep sea should result, at least in part, from increased food specialization by community members and thus avoidance of competitive overlap. Coryphaenoides armatus must be considered a generalist in its feeding habits, for it apparently will eat whatever it encounters, including objects with no food value whatsoever. This fact, and the finding of material clearly from the surface, such as the vegetables and bird fragments, is in keeping with the prediction (DAYTONand HESSL~t, 1972) that deep-sea fish should be extreme food generalists capable of locating and consuming large and rapidly settling material. Since large C. armatus feed mostly on midwater animals, however, the influence of this fish on the bottom must be primarily as a disperser of food particles rather than as a predator involved in the diversitymaintaining scheme proposed by Dayton and Hessler. Because C. arrnatus is so widespread and because it may form a considerable fraction of the fish population at depths below 2500 m (GREY, 1956), its activities must be taken account of in discussions of deep-ocean ecology. Acknowledgements--We extend our thanks to R. H. BACKU$,N. B. MARSHALL,W. B. P~AitC"lt,and G. T. Rowe for their reading of the manuscript. The following people gave generously of their time in the identification of stomach contents: S. H. B ~ w t x ~ (plants), S. P. GARNER(isopods and amphipods), D. C. JtmgJ1,vs (decapods and euphausiids), P. T. PoLt.Om (worms), and J. E. ~ D O a C (otoliths). To all we are grateful. This work was supported by National Science Foundation grant GA 31235 X, a grant to the Department of Biological Sciences, Wellesley College, from the E. I. du Pont de Nemours Corporation, and a work-study grant from Wellesley College.
REFERENCES
BULLI$H.R., JR. and R. C u ~ w s , JR. (1963) Another look at the royal red shrimp resource. Proceedings of the Gulf and Caribbean Fisheries Institute, 15th annual session, pp. 9-12. CLARKE M. R. (1962) The identification of cephalopod "beaks" and the relationship between beak size and total body weight. Bulletin of the British Museum (Natural History), 8(1), 419--480. DAYTON P. K. and R. R. HESSLER (1972) Role of biological disturbance in maintaining diversity in the deep sea. Deep-Sea Research, 19, 199-208. GREY M. (1956) The distribution o f fishes found below a depth of 2000 meters. Fieldiana Zoology, 36(2), 75-337. H ~ R. E. (1952) Zoogeography of the bathypelagic fish Chauliodus. Systematic Zoology, 1(3), 112-133.
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I w ~ q ' o T. and D. L. STERN(1974) A systematic review of the rattall ~ (Maorouridae: Gadiformes) from Oregon and adjacent waters. Occasional Papers of the California Academy of Sciences, No. 111, 1-79. MAaSHALL N. B. and T. IWAMOTO(1973) Family Macrouridae. In: Fishes of the western North Atlantic. Memoir, Sears Foundationfor Marine Research, No. 1, part 6, pp. 496-662. MoRRow J. E., JR. (1964) Family Chauliodontidae. In: Fishes of the western North Atlantic. Memoir, Sears Foundationfor Marine Research, No. 1, part 4, pp. 274-289. P s ~ c ~ W. G. and J. W. AMSLeR (1974) Food habits of deep-sea macrourid fishes off the Oregon coast. Deep.Sea Research, 21, 745-759. Rowe G. T. (1972) The exploration of submarine canyons and their benthic faunal assemblages. Proceedings of the Royal Society of Edinburgh (B), 73(17), 159-169. S ~ H. L. (1968) Marine benthic diversity: a comparative study. The American Naturalist, le~(925), 243-282. SCHO~_~ A. and G. T. ROWE(1970) Pelagic Sargassum and its presence among the deep-sea benthos. Deep-Sea Research, 17, 923-935. SHANNONC. E. and W. WEAVER(1963) The mathematical theory of communication, University of Illinois Press, 117 pp. VINOORADOVM. E. (1962) Feeding of the deep-sea zooplankton. Rapports et proc~s-verbaux des rdunions. Conseilpermanent pour rexploration de la met, 153(18), 114-120.