ISSN 00329452, Journal of Ichthyology, 2010, Vol. 50, No. 1, pp. 100–104. © Pleiades Publishing, Ltd., 2010. Original Russian Text © V.V. Napazakov, 2010, published in Voprosy Ikhtiologii, 2010, Vol. 50, No. 1, pp. 104–108.

The Diet of WhiteSpotted Greenling Hexagrammos stelleri (Hexagrammidae) on the West Kamchatka Shelf V. V. Napazakov Pacific Research Fishery Center (TINROCenter), per. Shevchenko 4, Vladivostok, GSP 690950 Russia email: [email protected] Received October 27, 2008

Abstract—On the basis of two trawl surveys made in the summer of 2005 and 2008 the diet of whitespotted greenling Hexagrammos stelleri, a widely distributed nearbottom sublittoral species, is investigated. The qualitative and quantitative characteristic of its food spectrum is given, depending on its linear size. The prin cipal food consists of crustaceans and fish, and secondary food items are mollusks, polyhaetes, and echiurids. With growth, the composition of crustaceans in the food changes: gammarids and mysids are replaced by shrimps, crabs, and hermit crabs. With growth, the significance of fish in the food of whitespotted greenling increases. In the food of the largest specimens, over 30 cm long, fish are dominant. DOI: 10.1134/S0032945210010121 Key words: whitespotted greenling, the West Kamchatka shelf, feeding, food composition, trophic status, size groups, habitat, planktophage, benthoichthyophage.

Whitespotted greenling Hexagrammos stelleri is a nearbottom, sublittoral species, widely distributed in Asian and American coastal waters of the northern part of the Pacific Ocean, from the Peter the Great Bay to California, is eurythermal and euryhaline, and lives on stony and siltedsandy grounds, to the depth 175 m, mostly concentrated at depths 5–20 m (Rass, 1962; Rutenberg, 1962; Hart, 1973; Gomelyuk, 2000; Fadeev, 2005). It attains a length 48 cm (Eschmeyer et al., 1983).

RESULTS AND DISCUSSION The range of depths at trawl stations where white spotted greenling was present in catches varied from 11

The present study is aimed at investigation of the food spectrum of whitespotted greenling depending on its length and at determination of the trophic status of this species in the bottom ichthyocene of the Weat Kamchatka shelf. MATERIAL AND METHODS

N 62°

Shelikhova Bay

60° 0 20

58° 0 50

Kamchatka

56°

The material was collected onboard RV Professor Kaganovskii in the West Kamchatka shelf in July of 2005 and 2008 (Fig. 1). Bottom trawlings were per formed by a DT 27.1 trawl with horizontal and vertical openings of 16 and 6 m, respectively. The contents of stomachs of specimens of whitespotted greenling caught in 2005 (147 specimens) and in 2008 (142 spec imens) were treated by the quantitativeweight method (Methodical Guide …, 1974; Guide…, 1986). For examination of food components, the digestion level scale was applied elaborated at the TINROCen ter (Chuchukalo and Napazakov, 1999). The length of fish was measured from the snout tip to the end of mid dle rays of the caudal fin (AC). 100

54°

July 2005

52°

July 2008

50° 154°

PACIFIC OCEAN 156°

158°

160°

162° E

Fig. 1. Sampling sites in July of 2005 and 2008.

THE DIET OF WHITESPOTTED GREENLING HEXAGRAMMOS STELLERI

to 75 m. However, main concentrations were confined to the inner shelf with depths to 40 m and nearbottom values of water temperature 0.2–11.3°C. In 2005, small whitespotted greenlings of the size group 10–15 cm fed principally on mysids (85%) and less so on gammarids (8%) and fish (7%) (table). In the food of fish 15–20 cm long, crustaceans domi nated by weight (83.2%) and were represented by approximately equal parts of mysids and small shrimps. Fish, predominantly juvenile Myoxocephalus polyacanthocephalus, made 14.5% of the total weight. The food of whitespotted greenlings 20–25 cm long consisted of mysids by 40.8%, decapod crustaceans by 14.4%, and gammarids by 1.3%. The sum of crusta ceans was 56.5%. The other food comprised fish (31%) and mollusks (2.6%). Whitespotted greenlings of the next size groups, from 25 to 30 cm long, fed mainly on fish (52.8%) and decapods (28.4%), less so on mol lusks (7.4%) and mysids (7.1%), and quite insignifi cantly on echiurids (2.2%), polychaetes (1.2%), and gammarids (0.9%). The largest whitespotted green lings, of few investigated specimens, fed on fish only. According to materials collected in 2008, in speci mens of 15–20 cm size, over a half of the ration con sisted of mysids (54.6%), approximately a third con sisted of decapods (28.7%), and the rest consisted of gammarids (16.7%). Greenlings of the size group 20– 25 cm fed on gammarids (35.4%), decapods (17.7%), mysids (13.9%), fish (12.7%), and not identified eggs (12.5%) and less so on echiurids (3.5%), mollusks (3.3%), and polychaetes (1.0%). The specimens 25– 30 cm of length fed predominantly on fish (52.9%), not identified eggs (20.5%), and decapods (12.0%), the part of each of other components, such as echino derms, mysids, gammarids, mollusks, and echiurids, was less than 5% of the total food weight. Greenling 30–35 cm long fed on fish (49.9%), echiurids (16.5%), not identified eggs (18.0%), decapods (8.5%), mol lusks (5.6%), and gammarids (1.5%). The interannual differences in the food composi tion in whitespotted greenling are more clearly expressed at comparison of food components identi fied at the species level, family, and genus. Indeed, in 2005, whitespotted greenling consumed more mysids, decapods, capelin, and sand lance and, in 2008, consumed more gammarids, staghorn sculpins Gymnocanthus, zoarcids, and fish eggs. However, mak ing interannual comparison of its diet one should take into consideration certain issues. Thus, in 2005, in contrast to 2008, specimens 10–15 cm long were examined which fed mainly on mysids. On the other hand, interannual differences in the diet of white spotted greenling may depend on its polyphagy and consumption of a wide range of prey. In other words, its ration to some extent reflects the structure of nek ton and nektobenthic communities of a particular habitat (its part which is used as food). As distribution of many species of these communities is mosaic, the variability of quantitative and qualitative composition JOURNAL OF ICHTHYOLOGY

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of food in polyphagopus whitespotted greenling increases. Therefore, on the basis of little material, it is not possible to get the unambiguous answer to the question what caused the revealed differences: struc tural interannual changes of nekton and nektobenthic communities or the impact of irregular distribution of particular species of these communities. At the same time, analysis of the composition of food items at the level of class demonstrated that principal components of its food are crustaceans, fish, mollusks, and echiu rids. The ratio of these components is stable in the interannual aspect (Fig. 2). It is known that the life cycle of whitespotted greenling consists of the pelagic and bottom stages (Gorbunova, 1962; Rutenberg, 1962; Antonenko and Vdovin, 2001). Whitespotted greenling living in the pelagial is a planktophage. According to Maksimenko (1999), the principal components of food of white spotted greenling from 6.0 to 8.2 cm in length (at the pelagic stage) in June–early August in Karaginskii Bay were mass and accessible in size forms of plankton and fish larvae. In the Sea of Japan, the pelagic period ends in August–September, approximately at the age of one year when whitespotted greenling attains 12–13 cm (Antonenko and Vdovin, 2001). Change of ecological niche is accompanied by change of trophic status— the whitespotted greending becomes benth ich thyophagous. In the beginning of life on the bottom an important role in its diet belongs to mysids and small shrimps of suitabe size (Antonenko and Pushchina, 2002; Chychukalo, 2006; our data). Behavioral traits of whitespotted greenling may be noted here obtained by Gomelyuk (2000) in the course of observations in nature. Whitespotted greenling mostly swims in the nearbottom layer, periodically rises to water column pursuing prey. It uses the surface of the bottom to rest briefly. With consideration of averaged data of food composition (the fish size was not indicated), Gome lyuk noted that, in Alekseev Bay in August 1986, the principal food components were Pandalus kessleri and Heptacarpus camtschaticus (making together 46.2%), fish (34.2%), and bivalve mollusks (11.2%). Abun dance in the food of bottom invertebrates directly indicates active use of the bottom both for rest and for hunting. In summer 1999, on the West Kamchatka shelf the diet of whitespotted greenling was studied by Kuz netsova whose data are published by Chuchukalo (2006). The diet of whitespotted greenling, which passed over to life on the bottom on the West Kam chatka shelf both by her and by our data collected in two voyages in 2005 and 2008, was similar (Fig. 2). In 1999, the investigated specimens of whitespot ted greenling up to 25 cm in length fed predominantly on mysids (62.5%) and, in larger fish, their part decreased to 4.0%. Shrimps were most significant in the food of specimens 30–35 cm in size. Of fish, whitespotted greenling consumed more frequently juvenile Theragra chalcogramma, Stichaeus punctatus,

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NAPAZAKOV

Food composition (% of weight) of whitespotted greenling Hexagrammos stelleri on the West Kamchatka shelf in July of 2005 and 2008 Size groups, cm 2005

Food composition

2008

10–15 15–20 20–25 25–30 30–35 Total 15–20 20–25 25–30 30–35 Total Echinodermata gen. sp. – Mysidacea gen. sp. 85.0 Gammaridea gen. spp. 8.0 Decapoda – Caridea gen. spp. – Crangon dalli – Argis lar – Argis sp. – Spirontocaris ochotensis – Spirontocaris sp. – Birulia sachalinensis – Hapalogaster grebnitzkii – Hyas coarctatus alutaceus – Telmessus cheiragonus – Chionoecetes opilio – Chionoecetes sp. – Paguridae gen. sp. – Brachyura gen. sp. – Mollusca – Cephalopoda gen. sp. – – Bivalvia gen. sp. (siphons, legs, including marginal pieces of mantle) Polychaeta gen. sp. – Echiurida – Echiurus echiurus – Pisces 7.0 Pisces gen. sp. – Mallotus villosus – Ammodytes hexapterus – Cottidae gen. sp. 7.0 Artediellus pacificus – Myoxocephalus – polyacanthocephalus Gymnacanthus detrisus – Gymnacanthus sp. – Microcottus sellaris – Podothecus sp. – Hexagrammos sp. – Zoarcidae gen. sp. – Lycodes sp. – Fish eggs – Not identified eggs – Other components – Mean index of fullness of stomachs, 269 ‰o Number of stomachs/samples 2/1 Part of empty stomachs, % 0 Mean length (AC), cm 13 Mean weight (total), g 26

– 41.8 – 41.4 41.4 – – – – – – – – – – – – – – – –

– 40.8 1.3 14.4 5.5 0.6 0.4 – 1.9 – – 0.9 – 2.8 2.1 – 0.2 – 2.6 – 2.6

– 7.1 0.9 28.4 14.2 3.4 – – 1.6 – – – – – – – 7.2 2.0 7.4 – 7.4

– – – – – – – – – – – – – – – – – – – – –

– 28.9 1.1 19.8 10.2 1.4 0.2 – 1.7 – – 0.5 – 1.6 1.2 – 2.4 0.6 3.9 – 3.9

– 54.6 16.7 28.7 – 14.1 – – – 4.9 – – – – – – 9.7 – – – –

– 13.9 35.4 17.7 – 9.5 – 1.3 0.6 – – – 2.7 2.7 – – 0.9 – 3.3 – 3.3

4.9 0.4 2.5 12.0 – 1.7 – – – – 4.5 – 3.5 0.5 – – 1.8 – 3.6 – 3.6

– – 1.5 8.5 – – – – – – – – – 1.3 – 6.0 1.2 – 5.6 5.6 –

2.1 5.9 11.8 13.3 – 3.8 – 0.4 0.2 0.2 1.9 – 2.2 1.3 – 1.6 1.7 – 4.0 1.5 2.5

– – – 14.5 4.5 – – – – –

2.7 4.2 4.2 31.0 4.2 14.0 4.8 – 2.4 0.7

1.2 – 2.2 – 2.2 – 52.8 100 7.4 83.9 9.3 16.1 20.6 – – – – – 3.1 –

2.0 3.1 3.1 39.3 8.0 11.8 9.4 0.0 1.4 1.4

– – – – – – – – – –

1.0 3.5 3.5 12.7 – – – 0.7 – –

– 4.1 4.1 52.0 – – – – – 4.9

– 16.5 16.5 49.9 – – – – – –

0.3 7.1 7.1 38.7 – – – 0.2 – 2.1

10.0 – – – – – – – 2.3 – 161

– 0.8 – – 0.3 – 2.2 1.6 1.8 1.2 236

– 2.4 – – – – 2.2 7.8 – – 190

– – – – – – – – – – 105

0.6 1.2 – – 0.1 – 2.0 3.4 1.2 0.7 –

– – – – – – – – – – 205

– – 7.1 – – – – 4.9 12.5 – 180

– – 13.7 4.1 – 27.0 – 2.3 20.5 – 165

– – 29.7 – – 3.7 – 16.5 18.0 – 232

– – 15.6 1.7 – 12.4 – 6.7 16.8 – –

21/2 4.8 18 93.5

86/5 0 23.3 160

34/4 2.9 27.5 274

4/2 147/14 28/2 25.0 2.04 7.14 33 23.6 16 457 183 37

55/3 7.27 23 156

46/3 2.17 28 297

13/2 142/10 0 4.9 52 25.9 476 208

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THE DIET OF WHITESPOTTED GREENLING HEXAGRAMMOS STELLERI

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% 100

80 60 40 20

0 15–20 20–25 25–30 30–35 35–40 10–15 15–20 20–25 25–30 30–35 15–20 20–25 25–30 30–35

July 1999

July 2005

July 2008

Mysidacea

Pisces

Decapoda

Gammaridea

Mollusca

Other components

Polychaeta Fig. 2. Food composition (% of weight) of different size groups of whitespotted greenling Hexagrammos stelleri on the West Kam chatka shelf in July of 1999, 2005, and 2008.

Hippoglossoides robustus, Liparis sp., and Gymnacan thus pistilliger (Chuchukalo, 2006). Other trophological studies indicate to similarity of the food spectrum of whitespotted greenling over the whole zone of its distribution in the northern Pacific. In Peter the Great Bay, the principal food items of juvenile whitespotted greenling are mysids and small shrimps and, in adults, they are decapod crustaceans (hermit crabs dominating), fish (mostly Engraulis japonicus, Acanthogobius flavimanus), and fish eggs, as well as gastropods and bivalve mollusks (Antonenko and Pushchina, 2002). In American coastal waters, according to Hart (1973), the food of whitespotted greenling consists of worms, crustaceans, and small fish and, in Saanich Bay (Strait of Georgia, the south west part of Canada), juveniles approximately 60 mm in length feed mainly on copepods, amphipods, juve nile decapod crustaceans and arthropods, Oikopleura, ostracods, and fish eggs. According to all trophological studies, on the West Kamchatka shelf the diet of whitespotted greenling comprises two main groups: crustaceans and fish. Sec ondary prey are mollusks, polychaetes, echiurids, and echinoderms. In the food of juvenile whitespotted greenling, the following crustaceans dominate: mysids and, less so, gammarids and shrimps. In whitespotted greenlings 20–30 cm in length, the food spectrum is the widest without clear domination of any prey. The JOURNAL OF ICHTHYOLOGY

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largest specimens (30–35 cm in length) feed mainly on fish. Thus, general regularities of age changes in the diet of whitespotted greenling are expressed by the following scheme: small crustaceans → averagesized decapod crustaceans → fish. Summarizing the aforementioned facts, it may be concluded that whitespotted greenling during its life occupies two habitats: the pelagial and the nearbot tom layer. In the first case, its trophic status is that of the planktophage and, in the latter case, it is that of the benthoichthyophage. In the beginning of life in the nearbottom layer when the linear size does not exceed 15 cm yet, its principal prey are mysids, gammarids, decapods, and polychaetes. With growth, mysids and small shrimps disappear from its diet. They are replaced by relatively large crustaceans, such as hermit crabs, spider crabs, and bivalve mollusks, and fish. Whitespotted greenlings attained the length of 30 cm and larger ones are predominantly ichthyophages. In different areas of Far East seas, the principal food of whitespotted greenling consists of crustaceans and fish and secondary food consists of echiurids, mol lusks, and polychaetes. REFERENCES 1. D. V. Antonenko and A. N. Vdovin, “Seasonal Distri bution of the Common Greenling Hexagrammos stelleri

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NAPAZAKOV (Hexagrammidae) in Peter the Great Bay (Sea of Japan),” Vopr. Ikhtiol. 41 (4), 490–494 (2001) [J. Ich thyol. 41 (9), 761–765 (2001)]. D. V. Antonenko and O. I. Pushchina, “Main Biologi cal Features of Fish of the Genus Hexagrammos in Peter the Great Bay (Sea of Japan),” Izv. Tikhookean. NauchnoIssled. Inst. Rybn. Khoz. Okeanogr. 131, 164–178 (2002). V. I. Chuchukalo, Feeding and Food Relationships of Nekton and Nektobenthos in Far Eastern Seas (TINRO Tsentr, Vladivostok, 2006) [in Russian]. V. I. Chuchukalo and V. V. Napazakov, “On Methods of Determination of Diurnal Diets of Feeding and the Rate of Food Digestion in Predatory and Benthos Eting Fish,” Izv. Tikhookean. NauchnoIssled. Inst. Rybn. Khoz. Okeanogr. 126, 160–171 (1999). W. N. Eschmeyer, E. S. Herald, and H. Hammann, A Field Guide to Pacific Coast Fishes of North America. Houghton Mifflin Comp. (Boston, USA, 1983). N. S. Fadeev, Guide on Biology and Fishery of Fish in the Northern Part of the Pacific Ocean (TINROTsentr, Vladivostok, 2005) [in Russian]. V. E. Gomelyuk, “Comparative Analysis Everyday Behavior and Mode of Life of Three Species of

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Hexagrammos (Hexagrammidae, Scorpaeniformes) in Summer,” Vopr. Ikhtiol. 40 (1), 79–90 (2000) [J. Ich thyol. 40 (1), 74–85 (2000)]. N. N. Gorbunova, “Reproduction and Development of Fish of the Family Hexagrammidae,” Tr. Inst. Okeanol. P. P. Shirshova, Akad. Nauk SSSR 59, 118–182 (1962). Guide for Study of Feeding in Fish (TINRO, Vladivos tok, 1986), p. 32 [in Russian]. J. L. Hart, “Pacific Fishes of Canada,” Fish. Res. Board Can. Bull. 180 (1973). V. V. Maksimenkov, “Feeding of Juvenile Greenlings of Hexagrammos stelleri in Karaginskii Bay of the Bering Sea,” Biol. Morya 25 (4), 318–320 (1999). Methodical Guide for Study of Feeding and Food Rela tionships of Fish in Nature (Nauka, Moscow, 1974), p. 254 [in Russian]. T. S. Rass, “Hexagrammidae (Pisces) and Their Intro duction into Northern Seas of the USSR,” Tr. Inst. Okeanol. P. P. Shirshova, Akad. Nauk SSSR 59, 634– 638 (1962). E. P. Rutenberg, “Review of Fish of the Family Hexagrammidae,” Tr. Inst. Okeanol. P. P. Shirshova, Akad. Nauk SSSR 59, 3–100 (1962).

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