ISSN 0032-9452, Journal of Ichthyology, 2008, Vol. 48, No. 9, pp. 770–777. © Pleiades Publishing, Ltd., 2008. Original Russian Text © A.M. Tokranov, A.M. Orlov, 2008, published in Voprosy Ikhtiologii, 2008, Vol. 48, No. 6, pp. 802–809.
Specific Features of Distribution and Ecology of Lycenchelys fedorovi (Zoarcidae) in Pacific Waters off the Northern Kuril Islands A. M. Tokranova and A. M. Orlovb a
Kamchatka Branch, Pacific Institute of Geography, Far Eastern Division, Russian Academy of Sciences, ul. Partizanskaya 6, Petropavlovsk-Kamchatskii, 683000 Russia e-mail:
[email protected] b Russian Federal Institute of Fisheries and Oceanography, ul. Verkhnyaya Krasnosel’skaya 17, Moscow, 107140 Russia e-mail:
[email protected] Received June 11, 2007
Abstract—On the basis of material for 1993–2002, data are provided on occurrence, spatial–bathymetric distribution, and size composition of Lycenchelys fedorovi, as well as on species that occur simultaneously with it in catches in Pacific waters off the northern Kuril Islands. This relatively scarce, medium-sized representative of the family Zoarcidae (maximum length of 42 cm, body weight 200 g) during the period of studies occurred only at the site to the south of the Fourth Kuril Strait in the range of depths 220–775 m at the near-bottom temperature of 1.6–4.2°C. The dependence between the depth of catch and sizes of L. fedorovi was analyzed. It was shown that the size of its catches in Pacific waters off the northern Kuril Islands is subjected to some interannual, seasonal, and diurnal dynamics. DOI: 10.1134/S0032945208090087
Wolf eels of the genus Lycenchelys Gill are representatives of the family Zoarcidae that inhabit mainly considerable depths of high altitudes of all oceans (Andriashev, 1954, 1955, 1958; Fedorov, 1973, 1976, 2000; Masuda et al., 1984; Anderson, 1994; Amaoka et al., 1995; Borets, 2000; Sheiko and Fedorov, 2000; Mecklenburg et al., 2002; Fedorov et al., 2003; Love et al., 2005). Presently known are 58 species of the genus Lycenchelys from different regions of the World Ocean, some of which were described only at the end of the 20th century (Toyoshima, 1983, 1985; Fedorov and Andriashev, 1993; Anderson, 1995; Fedorov, 1995a, 1995b). Among them is also Lycenchelys fedorovi that inhabits the upper bathyal zone of Pacific waters of the northern Kuril Islands; it was described as an independent species only in 2000 (Anderson and Balanov, 2000). Since most known today Lycenchelys species belong to rare representatives of deep-water ichthyofauna (Sheiko and Fedorov, 2000), whose catches are single, and catches in most cases do not exceed several individuals, published data on their distribution and biology are extremely fragmentary and restricted, as a rule, to indication of sites, depths of catch, and maximal sizes (Shmidt, 1950; Andriashev, 1954, 1955, 1958; Fedorov, 1976, 2000; Mecklenburg et al., 2002; Love et al., 2005). Despite the fact that L. fedorovi in Pacific waters of the northern Kuril Islands is characterized as a “common” species (Sheiko and Fedorov, 2000, indicate it as Lycenchelys sp. 2), the currently available
information gives only a general idea of its distribution and some features of biology (Orlov, 1998; Anderson and Balanov, 2000). From 1993 to 2002, in the framework of the program of study of poorly studied and little exploited fish of the continental slope of Far Eastern seas in Pacific waters of the northern Kuril Islands and southeast Kamchatka, workers of the Russian Federal, Kamchatka, and Sakhalin Research Institutes of Fisheries and Oceanography (VNIRO-KamchatNIRO-SakhNIRO) on board Japanese trawlers Tomi-Maru-53, Tomi-Maru-82, and Tomi-Maru-58, whose special equipment made it possible to perform bottom trawlings at the sites of the shelf and continental slope with a dissected topography, performed several joint scientific and commercial cruises, during which materials characterizing the composition of bottom ichthyocenoses of the lower part of the shelf and the upper bathyal zone of this region, as well as regularities of distribution and biology of different fish species, were collected. The information obtained during these cruises permits a more comprehensive characteristic of the occurrence, spatial–bathymetric distribution, and some features of biology of L. fedorovi in the upper bathyal zone of Pacific waters off the northern Kuril Islands. MATERIAL AND METHODS Materials and methods used while preparing this paper are analogous to those described in several of our
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SPECIFIC FEATURES OF DISTRIBUTION AND ECOLOGY Table 1. Some quantitative indices of occurrence of Lycenchelys fedorovi in catches in the upper bathyal zone of Pacific waters off the northern Kuril Islands from 1993 to 2002 Indices
Maximum Average values value
Proportion in catches, % 0–1.384 0.039 Total number of fish, individuals 1–611 12.50 Number of fish per an hour trawling, 0–158 2.54 individuals Total weight, kg 0–21 0.60 Weight per an hour trawling, kg 0–4 0.10 Length (TL), cm 14–42 31.54 Body weight, kg 0.01–0.20 0.071 Depth, m 220–775 465 Near-bottom temperature, °C 1.6–4.2 2.93 Number of catches with the species 248
earlier publications (Tokranov and Orlov, 2004, 2005; et al.). The data on 248 catches in which L. fedorovi was recorded during studies were analyzed. The duration of most trawlings was several hours, and they were performed at sites with dissected bottom topography and abrupt drops in depth; their bathymetric range rather frequently reached 100–200 m. Therefore, in determining the upper and lower boundaries of occurrence of L. fedorovi, we considered only trawlings performed in a relatively narrow range of depths, no more than 30–40 m. To characterize size composition, we used results of measurements of 294 individuals (of them, 151 individuals with weighing) performed from May to December 1993–2002. Fish were selected directly from catches. In all L. fedorovi, using a standard measuring board, total length (TL) was measured with an accuracy to 0.5 cm; weighing was performed on spring balance with an accuracy to 0.01 kg. RESULTS AND DISCUSSION In the study area, L. fedorovi is currently considered a rather common species (Sheiko and Fedorov, 2000); however, judging from the frequency of occurrence and the amount of catches from 1993 to 2002, its numbers in Pacific waters off the northern Kuril Islands are relatively low (Table 1). It dwells more often jointly with representatives of ichthyo- and teuthofauna most typical and numerous at sites of the upper zone of the continental slope with a dissected bottom topography and rocky grounds covered with numerous sponges. In most cases (frequency of occurrence more than 90%) during observations in catches, it was present together with five fish species—Sebastolobus macrochir, Sebastes borealis, Malacocottus zonurus, Elassodiscus tremebundus, and Atheresthes evermanni, as well as Berryteuthis magister (Table 2). During the entire 10-year period of studies, the proportion of L. fedorovi in trawl JOURNAL OF ICHTHYOLOGY
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Table 2. Species composition of catches (frequency of occurrence, %) with Lycenchelys fedorovi in the upper bathyal zone of Pacific waters off the northern Kuril Islands from 1993 to 2002 Species Malacocottus zonurus Sebastolobus macrochir Berryteuthis magister Sebastes borealis Elassodiscus tremebundus Atheresthes evermanni Careproctus furcellus Bathyraja maculata Careproctus cf. cyclocephalus Albatrossia pectoralis Bathyraja aleutica Reinhardtius hippoglossoides matsuurae Bathyraja matsubarai Icelus canaliculatus Sarritor frenatus Icelus perminovi Elassodiscus obscurus Sebastes alutus Careproctus roseofuscus Coryphaenoides cinereus Bathyagonus nigripinnis Sebastes aleutianus Bothrocara brunneum Bathyraja violacea Anoplopoma fimbria Theragra chalcogramma Careproctus cypselurus C. rastrinus Sebastolobus alascanus Clidoderma asperrimum Artediellichthys nigripinnis Antimora microlepis Lycodes brunneofasciatus L. albolineatus Rhinoraja taranetzi Hippoglossus stenolepis Triglops scepticus Bathyraja minispinosa Careproctus zachirus
Frequency of occurrence, % 96.8 96.8 93.2 92.7 91.1 90.7 83.9 78.2 71.4 68.6 62.9 55.2 54.4 53.2 52.8 40.7 36.7 35.9 35.5 35.5 34.7 33.9 25.8 25.4 23.4 22.6 22.6 19.8 19.0 18.2 17.3 16.9 17.3 15.3 15.3 13.7 13.3 12.5 12.1
Note: The table contains only “common” (frequency of occurrence 10–50%) and “numerous” (more than 50%) fish species according to gradation by Sheiko and Fedorov (2000).
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N 50°
49° Catch, individuals/hour 50 48°
154°
155°
156°
157°
E
Fig. 1. Distribution of Lycenchelys fedorovi in Pacific waters off the northern Kuril Islands (May–December 1993–2002). Thin line shows isobaths of 100, 200, 500, and 1000 m.
catches at depths larger than 200 m averaged 0.039% of the total number of caught fish, only in rare cases exceeding 1%. True enough that, taking into consideration small sizes and the eel-shaped form of the body of this representative of the fam. Zoarcidae that enable some individuals to pass through the trawl mesh, the amount of trawl catches apparently gives a slightly underestimated idea of the physical numbers of this species in the study region. It is evidenced by the fact that all noticeable catches of L. fedorovi (including maximum) coincide with a considerable additional catch of sponges (to 2–3 kg and over) that prevent fish to pass through the trawl mesh. Despite the fact that, from May to December 1993– 2002, the area of Pacific waters off the northern Kuril Islands and southeast Kamchatka from 47°50′ to 52°10′ was embraced with a dense network of trawlings (more
than 10 000 at depths of 83–850 m), L. fedorovi constantly occurred in catches only at the site to the south of the Fourth Kuril Strait (Fig. 1); the main area of its habitation where catches more than ten individuals per an hour trawling were recorded (maximum, 106 and 158 individuals) was the southeastern slope of the seamount of the northern link of the external Kuril Ridge (site from 47°50′ to 48°50′ N). True enough, in most cases here also the catches of this eelpout did not exceed two to five individuals per an hour trawling. According to modern concepts, L. fedorovi is a mesobenthal species (Fedorov, 2000) presently known from depths of 190–700 m (Anderson and Balanov, 2000) and is a component of mesobenthal ichthyocenosis (Sheiko and Fedorov, 2000). Analysis of trawl catches indicated that, from May to December 1993– 2002 in Pacific waters off the northern Kuril Islands, JOURNAL OF ICHTHYOLOGY
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Our materials enable us to trace seasonal changes in the depth of habitation of L. fedorovi in Pacific waters off the northern Kuril Islands. On the whole, from May to December, the average value of this index varied from 456 to 495 m, except November, when it comprised 390 m, which is most likely determined by a limited amount of material. From June to November, the upper boundary of habitation of L. fedorovi never exceeded 303–343 m, and only in May and December did it reach 270 and 220 m, respectively (Fig. 3). Our results of analysis of the spatial–bathymetric distribution of L. fedorovi in Pacific waters off the northern Kuril Islands on the whole agree well with data reported in the paper by Anderson and Balanov (2000). The sites of catch and the bathymetric and thermal ranges of habitation of this species coincide, although its maximum catches were recorded by us slightly deeper and at higher near-bottom temperatures (Fig. 2). True enough, Anderson and Balanov suggested that the lower boundary of habitation of the species under consideration is below 800 m since the frequency of its occurrence in catches increased with an increase in depth. This suggestion is not supported by our materials: despite the fact that, from 1993 to 2002, several trawlings were performed in the range of 801–850 m, L. fedorovi was never recorded deeper than 775 m, and the overwhelming majority of its individuals were caught in the range of depths 551–600 m. Apparently, the main area of habitation of L. fedorovi, as of several other mesobenthal species, is the upper zone of the continental slope up to 800 m. Analysis of relationship between the depth of catch and the average weight of L. fedorovi allows the conclusion that the bathymetric distribution of its individuals exhibits a tendency for a decrease in sizes of caught fish with an increase in depth. For instance, if, in the uppermost part of the continental slope (depths smaller than 400 m), the weight of L. fedorovi from 1993 to 2002 averaged 110 g, at depths larger than 500 m, it did not exceed 70–80 g (Fig. 4). A stepwise pattern of change in this index at different depths, in our opinion, is considerably determined by imperfect methods of weighing of fish similar to L. fedorovi under vessel conditions. Thus, as some other representatives of ichthyoJOURNAL OF ICHTHYOLOGY
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Number of fish, %
this representative of the fam. Zoarcidae was recorded at depths of 220 to 775 m at near-bottom temperature values of 1.6 to 4.2°C (Table 1). However, most individuals were caught in the range of depths 551–600 m (more than 45%) at a temperature above 3°C (about 76%) (Fig. 2). In the same bathymetric and temperate ranges, the highest values of average catches per an hour trawling were also recorded, 9.07 and 4.87 individuals, respectively. The increased concentration of L. fedorovi at depths of 401–450 m (22%) is apparently determined by the seasonal feeding migration of its adult individuals that after terminating spawning at the beginning of autumn (Anderson and Balanov, 2000) ascend for feeding along the continental slope.
Number of fish, %
SPECIFIC FEATURES OF DISTRIBUTION AND ECOLOGY 50 45 40 35 30 25 20 15 10 5 0
45 40 35 30 25 20 15 10 5 0
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(a)
600 501–550 351–400 451–500 551–600 . Depth, m (b)
4.0 Near-bottom temperature, °C
Fig. 2. Bathymetric distribution (a) and occurrence depending on near-bottom temperature (b) of Lycenchelys fedorovi in Pacific waters off the northern Kuril Islands (May– December 1993–2002).
0 100 200 300 400 500
5
6
7
Month 8 9
10
11
12
600 700 800 Depth, m Fig. 3. Seasonal dynamics of bathymetric range of habitation (vertical lines) and average depth of catch (circles) of Lycenchelys fedorovi in Pacific waters off the northern Kuril Islands (May–December 1993–2002).
fauna from Pacific waters off the northern Kuril Islands (Tokranov and Orlov, 2001), small individuals of L. fedorovi occur mainly at large depths, while the largest fish stay mainly near the upper boundary of habitation. The available materials allow us to analyze the interannual, seasonal, and diurnal dynamics of catches of
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Average weight, kg 0.12 0.11
R2 = 0.4635
0.10 0.09 0.08 0.07 0.06
