Characteristics of Feeding of Three Species of Wolffishes in the Northwest Atlantic

NOT TO BE CITED WITHOUT PRIOR REFERENCE TO THE AUTHOR(S)

Northwest Atiant,c Fisheries Organization

Serial No. N562 NAFO SCR Doc. 82/VI/69

SCIENTIFIC OUNCIL MEETING - JUNE 1982

CHARACTERISTICS OF FEE1 ING OF THREE SPECIES OF WOLFFISHES IN THE, NORTHWEST ATLANTIC

by L.K.K bikovskaya PINRO, 1 urmansk, USSR Abstract Qualitative and cluntitative-mass analysis of stomachs content in 3 species of wolffihes exposed similarity in rations of Atlan- tic and spotted wolffi, hes. A degree of similarity between northern wolffish and two other species lessens because A. latifrons feed on bathypelagic organisms Wolffishes fed mos. actively on the Flemish Cap Bank. Northern wolffish have worse inc ices than Atlantic and spotted wolffishes have. Introduction Feeding of traditinal objects of fishery in the Northwest Atlantic, such as cod,O)eaked redfish, grenadier, halibut is in the focus of investigation -during a long time (Zheltenkova, 1961 ,19?2; Yanulov, 1963; Konstaniinov, 1968,1972; Konstantinov, Turuk, 1968; Podrazhanskaya, 1969; hlruk, 1973). The present paper presents characteristics of feeqing og 3 species of wolffishes: Atlantic, spotted and northern i divisions of the South Labrador, Grand New- foundland Bank (3K, 31., and the Flemish Cap Bank. There were no such investigations in the previous years, though in some papers concerning feeding andifood competition of the Barents Sea and Northwest Atlantic fis] es some brief characteristics of food spectra of wolffishes are give and the coefficient of similarity in feeding (with other fishes) isi calculated (Baranenkova et al.,1960; Turuk, 1980). Many authors iii icate similarity in feeding of Atlantic and spotted wolffishes, pa4ticularly, the fact that Echinodermata, molluscs, Crustacea are diminant in it It is indicated that feeding on bathypelagic Invertbrata is specific for northern wolffish, rather often their stmachs are full with Cten6phora and medusas which distinguish A.Laifrons from other species (Barsukov, 1959, 1961 ; Barsukov, Nizovtev, 1960; Baranenkova, 1960; Turuk, 1980). The present paper )s aimed to generalize the materials on wolffishes feeding in Divi.ions of South Labrador (20"), Grand Newfound

land Bank (3K, 3L), Flemish Cap Bank (3M) for 1977-1981, to give qualitative and quantitative-mass analysis of the data available. Material and methods Field analyses of wolffishes feeding made during 4 spring-summer and 3 autumn-winter cruises of R/Vs "Persey III", "Suloy" and "N.Kononov" in 1977-1980 served as the basic material for the present paper (Table 1). Besides, in the R/V "N.Kononov" cruise in May-August 1981 several samples of stomachs were fixed in 4% formalin for their consequent treatment. All the stomach content was processed by the method of quantitative-mass analysis. Some dozens of wolffishes were frozen for their further treatment in laboratory conditions. All the fishes were weighed, measured, their stomachs were treated. Analyzing the primary data we made such calculations: Frequency of occurence of food components in fish stomachs calculated by the total number of stomachs (including empty); Degree of stomach fullness; 0-empty, 2-slight filling of the stomach, 1-some organisms are found, 3-full stomach, 4- walls of the stomach are stretched; Average index of stomach fullness calculated as mean arithmetical from index of fullness of every stomach examined; Average general index of stomach fullness (in 0/000; Index of stomach fullness by frequency of occurence of food components (in 0/000); Coefficient of food similarity (CFS) by Yanulovs formula (1963). CFS= • 100% where N -sum of maximum, n - sum of minimum values of frequency of food components occurence in fishes compared.

At complete difference of food the CFS equals to zero and at complete similarity -100%. Feeding of the Northwest Atlantic wolffishes First of all it is worth mentioning about one most characte- ristic biologic pecUliarity of wolffishes - a specific construction of dental system. All the species have much in common: strongly developed teeth are located on intermaxillae, mandibles, palate bones and vomer. With the help of hook-shaped teeth located on the frontal parts of maxillae and mandibles wolffishes tear the food off the substrate. Conic and round teeth on sides of jaws, on vomer and palate bones of Atlantic and spotted wolffishes which serve for crushing of solid external skeletons of bottom animals rub of rather quickly and they are replaced by new ones annually. Fangs of northern wolffish are smaller and sharper than those in other species, they are not rubbing off. Apparently, they are not accustomed fro tearing off the organisms from the substrate and serve mainly for retaining the floating food; many morphologic features of northern wolffish testify to the fact that they are to a lesser degree connected with the bot- -3- tom than other speci s of wolffish (Barsukav, 1959 9 1961; Barsukov, Nizovtsev, 1960). Species composit on of food objects in wolffishes is given in Tables 2,3. The f eld analysis showed that a great variety of organisms were found in wolffishes stomachs, though only some of them were the main f od objects. The most widely-distributed objects of molffishes eeding are Echinodermata mainly Ophiurae (Table 4). A considerable lace in A.lupus feeding take also bivalve molluscs, Gastropoda crabs. Stomachs of A.minor often contain crabs and worms. Ech nodermata and crabs are frequent in northern wolffish feeding but compared with other species of wolffishes organisms with solid carapace are of less importance, these species more often feed on f oating Mollusca: Ctenophora, medusas which testifies to a lesse connection of A.latifrons with the grounlk. In stomachs exa ines all external skeletons of bottom organisms were almost al ays crushed. Sand, silt and stones are frequent in wolffishes stomas s. Thus, our inves igations completely conform to the opinion that Atlantic and sp tted wolffishes are typical benthophages which have a conside able coincidence of feeding spectra. Coeffi- cient of food simil. ity for these species is rather high: 69.9%. The greatest differe ce in feeding is between Atlantic and nor- them wolffishes: CF = 32.9%. The degree of food similarity in these species is lo er due to feeding on different organisms. Coefficient of food similarity of spotted and northern wolffishes equals to 42.5%. Foo composition of wolffishes in different areas differs slightly. Indices of sto ach fullness for Atlantic and spotted wolffishes vary in diffe ent areas but they are always higher than those of Northern wo lffish. The results of analyses of the fixed and frozen samples e given in Table 5. High values of stomach fullness indices in fish analysed and also higher average indices of stomach fullness in spring-summer compared with those in autumn- winter (Table 6) al ow us to consider that spring-summer is the period of an intens ve feeding of wolffishes.

RE ENCES Baranenkova A.S., B• sukov V.V., Ponomarenko I,J., Syssoeva T.K., Khokhlina N.B., 196• . Morphological peculiarities, distribution and fe ding of the young of Anarhichas lupus L., A. min• r Olafsen, A. latifrons Steenstrup et Hallgrim- sson. 4 ool.zhurnal, v.39,vyp.8:1186-1200. Barsukov V.V., 1959. Anarhichadidae USSR fauna Fishes. v.5, vyp.5: 173.

Barsukov V.V., 1961. Some observations on Anarhichas latifrons Steene strup et Hallgrimsson. Voprosy ichthyologii, v.1, vyp.1(1b):19-28. Barsukov V.V., Nizovtsev G.P., 1960. On feeding of the Barents Sea wolffishes. Trudy Murmanskogo biologicheskogo instituta, vyp.2(6):203-206. Konstantinov K.G., Turuk M.N., 1968. Two types of cod dayly vertical migrations. Materialy rybokhoz. issledov severn. bass. Murmansk, vyp.XI:105-1100 Konstantinov K.G., Podrazhanskaya S.G., 1972. Feeding and food competition of grenadier (Macrurus rupestris) and other deep-water fishes in the Northwest Atlantic. Trudy PINRO, Podrazhanskaya S.G., 1969. Feeding of roundnose grenadier (M® rupestris) in some divisions of the Northwest Atlantic and those of Iceland. Tr.molodych uchenych VNIRO, vyp.1: 105-110. Turuk T.N., 1973. Diurnal periodicity of feeding and vertical migrations of cod Gadus morhua L. in the Labrador and Newfoundland waters. Voprosy ichthyologii, vo13, vYP.2(79):328-3430 Turuk T.N. Postolaky A.I. Feeding and food relations of some fish species in the Labrador and Newfoundland areas. NAFO SCR Doc080/VI/70, Ser. No.1180

Yanulov K.P., 1963. Feeding of beaked redfish (Sebastes mentella Travin) in waters of Newfoundland and Labrador. Voprosy ichthyologii, v.3, vyp04(29):708-726v Zheltenkova M.V., 1961. Shorygins works on studying of feeding and food relations in fishes; development of these stu- dies® Tr. VNIRO, v0XV:26-37. Zheltenkova M.V., 197a. Some data on feeding of the North Atlantic fishes. Tr. VNIRO, v.XXVII, vyp02:204-224.

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Table 2 Food composition and partial indices of stomachs fullness (in 0/000) (fixed material)

• 3 K. Objects of feedin :north :Atl. :spot.north Atl..spot.:north:.• • • Atl..north• • . Hydroidea 0,7 0,5 3,2 1,4 Themisto libellula 0,2 Gammaridea 2,7 Calathura brachiata 3,1 Brachyura sp. 0,1 0,4 1,7 4,4 Ilyas sp. 7,3 Pagurus pubescens 0,1 5,2 11,1 91,6 Pandalus borealis 12,6 5,3 3,0 7,4 Solariella obscura 1,5 Trichotropis borealis 0,I 9,1 36,1 Buccinum sp. 109,1 7,2 15,1 4,5 27,2 Gastropoda spp. Bivalvia 27,1 5,5 1,9 2083,4 2,3 Strongylocentrotus 5,3 18,8 10,3 7,0 Clypeastroidea 1,1 105,4 395,7 7,5 124,7 12,4 Ctenodiscus crispatus Ophiocten acuLeata 11,3 3,7 • Ophiura sarsi 0,1 3,1 26,4 0,3 0,6 Ophiura sp. 37,1 1,8 3,2 7,9 121,4 338,9 Ophiocantha bidentata 12,3 Gorgonocephalus Tubes Polychaeta 0,1 1,2 0,8 1,8 0,I Sebastes mentella 422,5 Gadus morhua m. 511,2 Raja . 16, Digested fish Digested food 4,2 2,9 49,2 85,8 211,0 20,7 117,9 13,0 229,3 16,5 1391 Stone, silt, sand 1,7 I,0 0,9 2,8 14,9 4,2

Table 3 Food composition and par ial indices of stomach fullness (in /000) rozen material)

oga•ser eala aasa. 3L Objects of feeding 3K Atlan. : spot.: Atlan. : Atlan : spot® : north . . . Hydroidea sp. 23,4 3,0 1,7 Calathura brach•ata 2,3 Hyas sp. 280,3 Brachyura sp. 15,6 376,9 0,4 20,32 Pandalus borealis 44,4 Solariella obscura 3,1 1,3 Buccinum sp. 66,5 Gastrbpoda spp. 14,5 5,1 6,7 15,7 0,9. Bivalvia sp. 0,4 2,2 CephalOpoda sp. 220,2 Strongylocentrotus sp. 33,9 433,8 Clypeastroidea sp. 114,2 444,7 Ctenodiscus crispatus 54,6 47,1 Ophiopholis aculeata 48,8 219,0 Ophiura sarsi 0,6 14,9 0,6 Ophiura spp® 56,0 31,9 9,9 Gorgonocephalus sp. 26,5 Tubes Polychaeta 7,1 8,5 0,4 1,2 1,8 1,1 Sebastes mentella 367,1 Digested fish 53,9 Digested food 12,6 94,6 26,2 72,3 12,0 Stone, silt, sand 47,5 4,6 1,8

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Table 5. Average index of sto ach fullness (in 0/000) of wolffishes in June-July 1981

2 3 3L 3 M Species • Fixed material Atlantic 114,7 185,1 861, 3 Spotted 341,1 728,2 Northern 31 3 37,2 17,4 139,2

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At 26I,4 329,4 182,4 Spotted 371.8 451,0 Northern 11,8

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Table 6 Average index of stomach fullness in spring-summer and autumn-winter cruises, 1977-1980

ear. 0X00 417: al. saga awe ma. dfa O. al. 4maa awa .15W0 AN. 4000, 00120 0.0 3 L • Season :Atl.: spot. : nor Atl. spotnor.: Atli spot; nor,i Atl.:spot.nor. 0 0 0 a . . 40120. AM. 0 • oeW awe 0000 .000 ,•00 0000 0000 .000 .0 00. .10, .000 0000 0010 spro-sum.. 2,0 2,6 1,3 2,2 2,7 1,4 2,3 2,6 1,5 2,2 2,1 1,0 1,1 1,2 0,4 0,5 0,5 0,6 1,8