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Article Excerpt
Introduction
The ragfish, Icosteus aenigmaticus (Fig. 1), with its soft musculature and cartilaginous skeleton, has been aptly characterized as a "puzzling fish with soft bones" (Fitch and Lavenberg, 1968; Moyle and Cech, 1996). Although external morphology has been described, most details of internal morphology and details of life history of this cold, deepwater species remain enigmatic and puzzling to science.
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Historically, ragfish have been collected sporadically from the Pacific Ocean continental shelf of North America beginning off southern California, extending northward to the Gulf of Alaska, along the Aleutian Islands, and then south to eastern central Japan. Commercial fisheries have taken ragfish from the surface waters of the North Pacific Ocean, the Gulf of Alaska, and the Bering Sea, in addition to relatively shallow coastal bays and inlets. Maximum depth of ragfish habitat off the continental shelf is unknown, as well as most factors of its life history. Only recently have detailed aspects of the species' early life history (ELH) been published (Matarese et al., 1984, 1989; Wing and Kamikawa, 1995; Wing et al., 1997). No specific study on the biology of adults, however, has been reported in the literature, except a preliminary note on fecundity (Allen, 1968).
There have been, and still are, difficulties with the taxonomy and classifcation of the species. Early ragfish descriptions and taxonomy were unaware of the changes in morphology from juvenile to adult stage. Clemens and Wilby (1961: 236), in combining juvenile and adult forms in the same species, summarized these changes as follows:
"... the pelvic fins, which are loosely attached in the young, become lost; the limp skin encroaches more and more over the anterior ends of the dorsal and anal fins thus giving a low count of the rays except under dissection; the modified scales disappear; the character of the pectoral and caudal fins is changed from round to pointed in the former, and from round to broadly emarginate in the latter; the yellow color and purplish spots change to a more somber brown as the adults attain greater size."
Not surprisingly, Lockington (1880), in his initial description of the species, named juveniles as "spotted ragfish," Icosteus aenigmaticus, while Bean (1887) called the first adult he described the "brown" ragfish, Acrotus willoughbyi. Goode and Bean (1895) used the common name of "fantail ragfish" as did many subsequent authors (Regan, 1923; Clemens and Wilby, 1949; Kamohara, 1962; Abe, 1963). Some reports omitted a common name, while others used the generic ragfish or "rag" fish (Higgins, 1921; Thompson, 1921). Crawford (1927) applied ragfish to an adult specimen, while Prichard (1929) applied the term to a juvenile, suggesting that the adult and juveniles were being considered as the same species. Barnhart (1936) bucked the unifying trend by using "speckled ragfish" for the juvenile and "giant ragfish" for the adult. Schultz (1936), however, employed the common name ragfish to both juveniles and adults at the species level, but he used "ragfishes" for the family Icosteidae (juveniles) and "pelagic fish" for the family Acrotidae (adults).
Following a hiatus in general scientific work associated with World War II, Fitch (1953) used "ragfish" in reporting on both juveniles and adults, as did Wilimovsky (1954). No mention was made of English common names when Japanese authors began reporting in English on ragfish juveniles recovered off Japan (Abe, 1954). Kobayashi and Ueno (1956) omitted any English common name but did note that the caudal fin as "very broad and fan-like," with a pictured specimen (69 cm TL) of an adult showing the tail slightly emarginate. Kamohara (1962:5) listed only the Japanese common name for a described ragfish but also reported on the tail "... the peduncle widening posteriorly to support the fan-shaped caudal." The common name of ragfish "became applied consistently when the juvenile and adult stages were recognized as the same species (Bailey et al., 1960; Clemens and Wilby, 1961).
Fishermen commonly contribute a plethora of common names for fish they catch, but when rarely encountered species are caught, the common name applied by taxonomists, if known, usually suffices. For the ragfish an exception may have been whalers apparently using their own unique common name (Cowan, 1938:97): "Dr. Robbins is confident that the 'bastard halibut' of the whalers is identical with the brown ragfish." I feel it likely that the general public tends to consider beached large female ragfish as some sort of Pacific salmon.
Gross external morphology and coloration differences between adult ragfish (Fig. 2A-E) and juvenile ragfish also influenced the history of taxonomic studies of the species. Gunther (1887:46), after reviewing the literature and examining two juveniles in his collection, named the species Schedophilus enigmaticus Steindachner, even though Steindachner, in an 1881 paper, used Icosteus enigmaticus. Gunther placed ragfishes in the family Coryphaenidae, stating that he had failed to find in published descriptions anything that would warrant a generic separation from Schedophilus or the creation of a distinct family "Icosteidae." Lockington (1880) also puzzled over taxonomic status when he listed the ragfish in the family Blennidae. Bean (1887) noted that the adult ragfish he described appeared to be closely related to Icosteus, but he did not specifically designate a family.
Reflecting the early tentative taxonomies, Dean et al. (1923:646) listed four kinds of "ragfishes" under the family Icosteidae (Acrotus, Icicthys, Icosteus, and Schedophilius medusophagaus). Both juveniles and adults were combined under one species (Acrotus willoughbyi Bean) and family Acrotidae (Ulrey and Greeley, 1928). The "rule of priority," however, assigns the name to Lockington with "ragfish" the official common name, the genus Icosteus, and family Icosteidae (Wilimovsky, 1954; Fitch and Lavenberg, 1968; Miller and Lea, 1972; Hart, 1973; Wheeler, 1975; Nelson, 1976; Matarese et al., 1984; Moyle and Cech, 1996).
There also has been difficulty in assignment of the family to higher taxa due to a continued puzzlement over ragfish evolutionary history. Thus Regan (1923: 612) wrote: "The exact systematic position of the Icosteidae is uncertain, but the great development of cartilage and the weakness of the bones is evidently secondary, and there is nothing in their organization to prevent the assumption that the Icosteidae represent a specialized and somewhat degenerate development of the Perciform type." Berg (1940:494) accepted Regan's opinion, and placed the family Icosteidae in a separate order Icosteiformes (Malacichthyes). Matarese et al. (1984), in their study of larval forms up to 2.8 cm in length, identified both blennoid and stromatoid morphological features. They summarized the present ragfish status as follows: "The systematic position of this group and its designation as an order or suborder is not well established. Greenwood et al. (1966) considered it a suborder of Perciformes (Icosteoidae) while Gosline (1973) elevated it to an order, Icosteiformes, a probable perciform derivative" (Matarese et al., 1984:576).
A black-and-white drawing of excellent quality of an early 26 cm long juvenile showing external morphology and the pattern and texture of the skin was published in Gunther (1887:46, Plate XLIV, Schedophilus enigmaticus). Goode and Bean (1895) conveniently placed line drawings of a juvenile and an adult together (Plate LXII), and included illustrations of other species with close affinities (Icicthys lockington, Centrolophus pompilus, Schedophilus medusophagus) (Plates LXI, LXII). Recent photographs of a juvenile appeared in Fitch (1953) and Fitch and Lavenberg (1968). Illustrations of adults were published by Jordan and Evermarm (1898:973) and Clemens and Wilby (1961:333). A color illustration of an adult can be found in Eschmeyer and Herald (1983:Plate 46). The most appealing historical photograph of an adult ragfish is that of the Yecny family arranged beside a suspended 152 cm (5 ft) specimen caught while sport fishing on 20 May 1940 from a breakwater at Monterey Bay, Calif. (Bolin, 1940:287). The most accurate depiction of the general shape and skin pattern of juvenile and adult ragfish is that in Hart (1973:386). Such general shape and skin patterns are evident in photographs of juvenile and adult specimens that only came to my attention during March 2002 (Fig. 3A, B).
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Prior to August 1999, I had assembled over 200 unpublished and published historical records on ragfish, with some historical records added in December 1999 and February 2000. During August 1999, I received from J. Heifetz (1) data on 620 ragfish specimens incidentally observed and recorded during studies on commercially important species taken by U.S. fishermen from California to the Bering Sea. These records from the NMFS Alaska Fisheries Science Center, Seattle, Wash., and records of ragfish existing in published literature, were primarily used to enlarge our knowledge of ragfish distribution, both geographically and ecologically. Much new biology and life history aspects of the ragfish came principally from the records of specimens taken by bottom trawlers operating off northern California and southern Oregon and by the California Department ofFish and Game (CDFG), Oregon Department of Fish and Wildlife (ODFW), and by the fisheries department at Humboldt State University (HSU), Areata, Calif.
Materials and Methods
Data Sources
Historically, ragfish have come to science through fishermen and citizens who retain specimens and voluntarily deliver them to fisheries management personnel, museum curators, and ichthyologists. My first experience with ragfish was in this tradition when, in 1958, a crew member of a commercial bottom trawler (F/V Sitka) operating out of Eureka, Calif., prevented the discard at sea of a single large female ragfish. The crew member, a personal acquaintance, phoned me from the dock to come and examine the fish. I observed a running-ripe female that subsequently became one of the four females in a preliminary study of ragfish fecundity (Allen, 1968).
From 1958 through 1989, a total of 39 fresh specimens taken by commercial trawlers landing catches mainly at Fort Bragg, Eureka, and Crescent City, Calif., were transferred to HSU for study along with another 44 specimens from northern California and southern Oregon, recorded and catalogued by the CDFG (Table 1). A mail survey in 1977 of 14 museums and agencies (excluding CDFG) with known fish collections produced 67 historical records. In 1998 and 1999 state and Federal fisheries biologists in Juneau and Petersburg, Alaska, forwarded 16 more ragfish records. Additional records of California ragfish recovered in 2000 were not incorporated into this report due to my desire to bring the report to a conclusion. Historical records were mainly of larger juveniles and mature females (Table 2).
Other important sources of ragfish data were found in published and institutional archival reports by governmental agencies engaged in monitoring and research associated with the management of North Pacific Ocean fisheries. One of the longest and most detailed of these studies was on early life history (ELH) stages (eggs and larvae) of commercially important marine fish species sampled from 1951 to 1984 by the California Cooperative Fisheries Investigation (CalCOFI). The sampling grid overlays three coastal zoogeographic provinces, a coastal upwelling zone, and three oceanic water masses of the eastern North Pacific (Moser et al., 1993; Moser et al., 1994). Other recent records of ELH stages of ragfish are those from the eastern North Pacific Ocean where specimens were sampled during studies on commercial groundfish stocks of the continental shelf from Sitka to Dixon Entrance (Wing and Kamikawa, 1995; Wing et al., 1997). An international effort during the 1990-91 fishing seasons to document incidental catches of fish, mammals, and birds of conservation concern in major North Pacific commercial surface gillnet fisheries for squid and salmon also recorded ragfish (INPFC). (2) Reports on three national fisheries listed 27 records of ragfish taken from generalized areas (Japan: McKinnell et al. (3); China: Yeh et al. (4); Korea: Park et al. (5)). No other data were included since the studies focused on the incidental catch of animals of international conservation concern.
Analysis of Historical Data
Most fresh adult ragfish delivered to HSU were measured (cm) for total length (TL) and standard length (SL), and for total and gonad weight (gm). Data on depth, location, and time of capture were furnished either by the person capturing the specimens or by CDFC biologists who examined the ragfish on the docks. Most useful data on 66 specimens >35 cm came from seven institutions (HSU, 34; CDFG, 15; CAS, 8; ABL, 3; BCPM, 3; UBC, 2; MLML, 1). (6) Smaller specimens (<35 cm SL) recorded in museum collections were immature juveniles, with available records containing only scant biological data. Data on juveniles were used primarily in studying distribution. CDFG ragfish records supplied by John Fitch (7) were for fish landed mainly south of Cape Mendocino, and measurements were similar to those taken on HSU specimens. Miscellaneous observations on some fish in HSU and CDFG included notes on stomach contents, whether eggs were running from the vent, and a few had measurements on length and weight of ovaries.
Metrics for larger ragfish were computed by D. Hankin and HSU fisheries students. (8) Specimens measured (cm) for TL only in the field were converted to SL by the equation: SL = 2.57 + 0.87 TL (R = 0.98, n = 41) (Osborn (8)). Specimens without weights were estimated by least-squares regression (Zar, 1984) using males and females combined (Wt = 6.27g; SL = 2.7cm; R = 0.98, n = 30) (Bremm (8)). For fecundity studies, missing weights of large females used only females. Equations describing fecundity, egg maturation, and relative size of gonads are presented in results.
Written comments on whether eggs were flowing freely from the vent of adult female were not specifically recorded for some female specimens collected by HSU and CDFG. These records probably indicated no running ripe eggs. Some specimens were damaged in transit to HSU, and a few ovaries were ruptured or damaged during examinations made prior to delivery to HSU. For a few females, the ovaries were the only part of the fish deposited at HSU. Sufficient data were available on 14 females delivered to HSU to enlarge the estimates of fecundity. Standard gravimetric methods as described in Allen (1968) were used in estimating egg numbers. In a preliminary study, from 5 to 27 aliquot samples of eggs, depending upon the size of the ovary, were taken from predetermined positions along both ovaries. Three categories of egg size were noted in most ovaries. A study of the mean diameter of the "large-category" eggs (1.0-3.0 mm) in two specimens (HSU 7, 9) found no difference in aliquots taken from 19 to 25 positions along the length of the ovary. This confirmed a preliminary study that eggs were maturing at equal rates in all portions of the ovary (Alien, 1968). Subsequently aliquots were sampled from 5 to 9 positions only.
The gonads of one specimen (HSU No. 25, total gonad length 31.5 cm), appearing peculiar in gross external morphology, were studied histologically. The external formalized most-anterior section of the ovary was creamy white in appearance, a middle section purplish in color with some whitish underlying patches, and a posterior section was grayish in color with some purple tinge. A final narrow section of the gonad attaching to the vent presented a much more granular texture than the rest of the gonad. Gonad fixation was in 10% Formalin, dehydration and embedding used a tertiary butyl alcohol series, with staining by hematoxylin and eosin. Transverse sections 10 mm thick of tissue sampled from left and right positions along the length of the gonad were studied for any histological changes that might have indicated incipient hermaphrodism in the specimen.
Ragfish Capture Gear
Many types of fishing gear have taken ragfish in the historic record. Not only is this information inherently interesting, but it can be of practical value when planning future ragfish studies. Knowing which depths and bottom substrates have been sampled by various gear can direct future research toward unsampled areas (Allen et al., 1961).
Hand Collections
The most unique acquisitions of ragfish arise from hand collections involving chance encounters with moribund or dead ragfish either washed up on beaches or stranded in adjacent shallow waters. Ragfishes used by ichthyologists initially describing the species were all from chance hand collections (Lockington, 1880: 3 specimens found on a fishmonger's display table in San Francisco in 1885; Bean, 1887: an adult from a beach at Damon, Wash., collected by Charles Willoughy, Indian agent). Another early specimen was hand collected by J. O. Snyder in 1906 from a beach at Pacific Grove, Calif. (6 cm fish, USNM 75159). Craig Carrothers, an HSU student, found a 9 cm SL juvenile in shallow water at the foot of a boat ramp located north of the north jetty entrance to Humboldt Bay, Calif. (9) A surprisingly large number of adults have been hand collected from the beaches of bays and inlets of southeastern Alaska (6 records furnished by Bracken (10) and Wing (11)). Other recoveries from beaches in southeastern Alaska were made by school children on field trips and by young boys on fishing trips near Kake and Petersburg, Alaska (Marsh, 1995; Kondro (12)). Marsh reproduced in his magazine article a photograph of one of these specimens being displayed by its captors.
Probably the most interesting example of a hand collection was that of a specimen taken from a Steller sea lion, Eumetopias jubata, in surface water by a sport fisherman at Outer Point near Auke Bay and about 3 mi. northwest of Juneau, Alaska, 9 May 2000 (Wing (13)). The fisherman was attracted by a surface disturbance caused by the sea lion and was able to collect the posterior trunk and tail of the ragfish. The remains (= 150 cm TL) were given to K Koski for delivery to ABL for identification.
Trawls
Many different trawls have taken ragfish: commercial bottom (otter) trawls, shrimp trawls of several designs, beam trawls, and midwater trawls. Historically, the largest number of ragfish records have come from adults taken by otter trawls used in a commercial fishery on the continental shelf between Camp Mendocino and Pt. St. George, northern California. Bracken (10) and Wing (13) recorded ragfish captures from inside waters of southeastern Alaska by both shrimp and beam trawls. A modified North Atlantic capelin net took an adult ragfish (130 cm) when fishing at 75 fm (137 m) over a bottom depth of about 300 fm (549 m) in the lower end...
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