Rock Sole Research Articles

Age Validation for Rock Sole in Hecate Strait, British Columbia

Abstract Rock soles Lepidopsetta bilineata in Hecate Strait, British Columbia, were tagged and injected with oxytetracycline (OTC). Otoliths from eight of nine tagged fish recaptured 2–3 years later showed fluorescing OTC marks. Both the years since application of the OTC mark and the occurrence of growth checks could be read correctly from burned cross sections of the otoliths. Estimated ages of recaptured fish were 6–11 years.

Determination of adenosine 5′-monophosphate in fish and shellfish using an enzyme sensor

An enzyme sensor for the determination of adenosine-5′-monophosphate (AMP) concentration in the muscle of fish and shellfish has been developed. The AMP sensor consisted of two immobilized enzyme membranes and an oxygen probe. AMP was oxidized to uric acid by AMP-deaminase, 5′-nucleotidase, nucleoside phosphorylase and xanthine oxidase, and oxygen consumed was monitored amperometrically by an oxygen electrode. The optimum conditions for the enzyme electrode were pH 7.8 and 30°C. Output current was reproducible within 4% of the relative error when a solution containing 10 m m AMP was used. One assay could be completed within 4 min and the sensor was stable for 100 assays over 30 days at 5°C. The sensor was used to determine AMP concentration in bream , Pagrosomus unicolor Quoy and Gaimard; sea bass, Lateolobrax japonicus ; flounder, Lepidopsetta bilineata ; abalone, Haliotis discus hannai ; and arkshell, Anadara broughttoni (Shrenk). AMP in a sample solution was also determined by a conventional method, giving satisfactory comparative results.

Tumours and microbial diseases of marine fishes in Alaskan waters

Abstract. In an effort further to define the current health status of demersal fish in the Bering Sea, 36 618 fish captured by otter trawl during 1976 were examined for pathological conditions. Of the 26 species examined, 22 were found to have no detectable abnormalities. The four species with abnormalities were Pacific cod Gadus macrocephalus Tilesius with pseudobranchial tumours and skin lesions, walleye pollock Theragra chalcogramma (Pallas) with pseudobranchial tumours, yellowfin sole Limanda aspera (Pallas) with lymphocystis, and rock sole Lepidopsetta bilineata (Ayres) with epidermal papillomas. The prevalence, geographical distribution and biological and pathological characteristics of affected individuals were determined.Pseudobranchial tumours of both Pacific cod and walleye pollock were occasionally found to be invasive. Fish bearing these tumours were distributed throughout the sampling area. The epidermal papillomas on rock sole resembled similar tumours found on several flatfish species along the West Coast of North America. The distribution of this disease appeared to be depth related. The virus‐caused lymphocystis growths were located on the ‘blind’ side of yellowfin sole. The highest frequencies of fish with lymphocystis were in the south‐eastern Bering Sea. Two main types of skin lesions were seen on Pacific cod: ulcers and ring‐shaped lesions. Isolates of bacteria (Pseudomonas sp.) were routinely obtained from the cod ulcers and may be the cause of this disease. The ring‐shaped skin lesions, when examined microscopically, contained unidentified epidermal basophilic bodies.

Influence of time and mode of exposure on biotransformation of naphthalene by juvenile starry flounder (Platichthys stellatus) and rock sole (Lepidopsetta bilineata).

Juvenile starry flounder (Platichthys stellatus) and rock sole (Lepidopsetta bilineata) were force-fed 56 μCi each of 1-3H-naphthalene dissolved in salmon oil. Values for radioactivity associated with naphthalene and the metabolite fraction were determined for various tissues and body fluids. Results show that these pleuronectids extensively metabolize dietary naphthalene. The rates of decline in naphthalene concentrations (expressed as disintegrations per minute per milligram of dry tissue) were greater than the rates of decline in metabolite concentrations (dpm/mg) in liver, blood, and skin; therefore, relative proportion of metabolites to naphthalene increased with time and at 168 hr after the initiation of the naphthalene-exposure, more than half of the total radioactivity in both species of fish was associated with the metabolites.

The frequency, distribution, and pathology of three diseases of demersal fishes in the Bering Sea

During September and October, 1975, bottom‐dwelling fish from the Bering Sea were examined for diseases. The three most commonly observed diseases and their frequency of occurrence were epidermal papillomas of rock sole (Lepidopsetta bilineata Ayres), 1‐0%; lymphocystis of yellowfln sole (Limanda aspera Pallas), 2‐1 %; and epidermal tumours of the pseudobranch of adult Pacific cod (Gadus macrocephalus Tilesius), 7‐4%. Both the appearance and the histological characteristics of epidermal papillomas on rock sole resembled those found on several species of flatfish in Puget Sound. The frequency of tumour‐bearing rock sole ranged from 0‐23%, with the highest occurrence at sampling stations around the periphery of the Bering Sea in water depths of 20‐30 fathoms (36‐54 m). The virus‐caused lymphocystis lesions were usually on the ‘blind’ side fins and skin surfaces of yellowfin sole, the largest lesions being found on the operculum, and the most common site of infection was the pectoral fin. The frequency of lymphocystis was 0‐15 %, with a gradual increase of prevalence from the northern to southern sampling stations. The Pacific cod tumours were always bilateral, and contained remnants of normal‐appearing pseudobranchial tissue on the surface or deep inside the tumours. Portions of some tumours were necrotic and liquefied. Tumour‐bearing cod were most commonly found in the south and south‐eastern Bering Sea and the frequency of affected cod ranged from 0‐100%.

Flatfish Densities Determined with a Diver-Operated Flounder Sampler

Densities of four species of flatfish: rock sole (Lepidopsetta bilineata), English sole (Parophrys vetulus), C-O sole (Pleuronichthys coenosus), and the speckled sanddab (Citharichthys stigmaeus) were determined by using a flounder sampler designed for use by a scuba diver biologist on sand bottom habitats. Under semicontrolled conditions the overall estimate of flatfish numbers was 91.0 flatfish/1000 m2 with a 95% confidence interval of ± 17.5. Biomass was estimated at approximately 7.4 kg/1000 m2.

The Life Cycle and Larval Development of Echinorhynchus lageniformis Ekbaum, 1938 (Acanthocephala: Echinorhynchidae)

The life cycle of Echinorhynchus lageniformis was completed experimentally in the laboratory, and the adult worm redescribed. Shelled acanthors ingested by the amphipod Corophium spinicorne penetrate the intestine within 2 days, remain attached to the intestinal serosa for about 10 days, and then drop free into the hemocoel. The acanthella becomes infective in 30 days at 23 C. The starry flounder, Platichthys stellatus, serves as the final host in estuarine waters of the Oregon coast. The acanthocephalan Echinorhynchus lageniformis Ekbaum, 1938 was first described from the starry flounder (Platichthys stellatus) and the rock sole (Lepidopsetta bilineata) collected in Departure Bay, British Columbia. It is a common parasite of the starry flounder on the Oregon coast in Yaquina Bay, Alsea Bay, and in the Columbia River estuary. The intermediate hosts for only four species of Echinorhynchus have been determined (Yamaguti, 1963): E. clavula (Dujardin, 1845) nee Hamann, 1892, E. gadi (Zoega) Miller, 1776, E. salmonis Muller, 1784, and E. truttae Schrank, 1788. Only in E. truttae has larval development been studied (Awachie, 1966). Prakash and Adams (1960) studied the histopathology of E. lageniformis in the starry flounder and Barnes (1968) studied its ecology in Yaquina Bay. The purpose of this investigation was to determine the life cycle of E. lageniformis and to study its development in the intermediate host. Because the original description of E. lageniformis lacks detail, the adult is redescribed. MATERIALS AND METHODS Specimens of starry flounder were collected primarily in Yaquina Bay with a 16-ft otter trawl and were transported to the Oregon State University Marine Science Center for study. The total length of each fish was measured, the intestine removed, and the contents examined for E. lageniformis. Worms were collected and placed in distilled water until fully extended. A number of gravid female worms were punctured in order to obtain eggs. The eggs placed in bay water and stored under refrigeration were viable for at least several months. The remaining worms were fixed in AFA, stained with Semichon's acetocarmine, cleared in methyl salicylate, and mounted in Harleco synthetic resin. The intermediate host was determined by allowReceived for publication 29 June 1970. ing various bay amphipods to feed on large numbers of eggs in small dishes. After 3 to 4 hr, the amphipods were transferred to aerated finger bowls and held at 23 C. After varying periods of time, amphipods were examined for infections. When the proper host was determined, large numbers were infected and examined at regular intervals. When recovered, immature acanthocephalans were studied alive in 0.5% saline, then made into permanent mounts in the same manner as adult worms. The time required for the development of an infective juvenile was determined by feeding larvae of various ages to young P. stellatus.

Rate of Development of Eggs of Rock Sole (Lepidopsetta bilineata Ayres)

not available

Demersal Quality of Fertilized Eggs of Rock Sole (Lepidopsetta bilineata Ayres)

not available

Cytological and Histological Studies on the Hybrid of Platichthys stellatus X Parophrys vetulus, with Notes on Its Backcross to P. vetulus

INOPSETTA ISCHYRA was first described as a distinct species, Parophrys ischyrus, by Jordan and Gilbert (1880) on the basis of four specimens. The species was redescribed by Villadolid (1927), but no indication of its possible hybrid nature was given. The first published hint of the species' hybrid origin was given by Norman (1934) who stated that Inopsetta may prove to be a hybrid between Lepidopsetta bilineata and Platichthys stellatus. Schultz and DeLacy (1936) concurred with this opinion, but later meristic and morphometric studies by Schultz and Smith (1936) indicated that Parophrys vetulus and not Lepidopsetta was one of the parents. No further work as regards the hybrid status of Inopsetta has been found, although Herald (1941) in reporting the fish from California, and Hubbs and Kuronuma (1942) in their discussion of flatfish hybrids, all seem to agree with the analysis by Schultz and Smith that Inopsetta is a hybrid between Parophrys and Platichthys. None of the above mentioned researches includes any discussion of gonadal development, either anatomic or cytohistologic. With infrequent exceptions animals found to be hybrids are sterile or partially fertile. The laboratory proof of fertility is usually difficult, so it is remarkable that few investigations have been undertaken to study the gonadal development of suspected hybrids. Kerkis (1933), for example, in his study of an intrageneric hybrid of Drosphila, found small gonads with gametogenesis being halted before meiosis could take place. Hubbs (1955) mentions grossly abnormal sperm in hybrid sunfishes. The bulk of the studies of hybrid fish, however, fail to describe even the gross anatomy of the testes or ovaries. In this study the gonads and the gonadal

Notes on the occurrence of Acanthocephala in Pacific fishes

Echinorhynchus gadi (Zoega) Müller has been found parasitic in various species of Pacific salmon. The amphipod Cyphocaris challengeri Stebbing serves as an intermediary host for this parasite in the region in which the investigations were carried out.Echinorhynchus lageniformis sp.nov. and Corynosoma strumosum (Rudolphi) both parasitic in the Starry flounder (Platichthys stellatus (Pallas)) and the Two-lined flounder (Lepidopsetta bilineata (Ayres)) are recorded with data on their occurrence.

Is Inopsetta ischyra (Jordan and Gilbert), from Puget Sound, Washington, a Hybrid Flatfish?

F OR some time the rare flounder of Puget Souna known as Inopsetta ischyra has been suspected of b ing a hybrid, although it was reported a a distinct species by Jordan and Gilbert (1880), who described it from 4 specimens, and by Villadolid (1927), who redescribed it on the basis of the 3 additional known specimens; these 7 specimens were all taken in the region of Elliot Bay and Holmes Harbor, Puget Sound. This nominal species is well known to trawl fishermen of Saratoga Passage, by whom it is called a bastard flounder. is said by them to be a hybrid between the starry flounder, Platichthys stellatus, and some other species. Capt. Michael Criscoula of the Trawler St. Michael, who saved for the junior author some of the specimens used in this report, is one of the fishermen who recognizes this fish at sight and regards it as a hybrid. This has also been the belief of Carl L. Hubbs and other ichthyologists for several years. The first printed statement that we have found indicating that Inopsetta ischyra may be a hybrid was that by Norman (1934: 376-377), who wrote: It is possible that the single known 'species' of Inopsetta from Puget Sound may prove to be a hybrid between Lepidopsetta bilineata and Platichthys stellatus. Schultz and DeLacy (1936: footnote 11) were of the same opinion until the present study was made. Only recently has it been possible to satisfy the senior author's desire of several years to analyze this problem. While engaged in a study of the fishes caught by the commercial fisher en in the Puget Sound Region, the junior author has collected 12 more specimens corresponding with the descriptions of I. ischyra: 4 from Saratoga Passage, off Oak Harbor, from January 26 to February 4, 1936; 7 from Saratoga Passage, off Watsak Point near Coupeville, from January 14 to February 12, 1936, and 1 from Port Discovery Bay, March 24, 1936. These 12 new specimens agree so completely with the 2 types in the United States National Museum (No. 27266), examined by the senior author, and with the 2 descriptions of Inopsetta ischyra, as to leave no doubt that they represent the same species, or hybrid combination. Several of the small-mouthed flounders of Puget Sound do not resemble Inopsetta ischyra closely enough to be considered possible parent species. Glyptocephalus zachirus and Microstomus pacificus have very small mouths, blunt heads, the profile rounded, s ooth scales, and elongate bodies, all of which characters, among others, clearly differentiate these 2 species from I. ischyra. Pleuronichthys coenosus and P. decurrens have a rounded caudal fin, the dorsal fin beginning on the blind side opposite upper or lower lip, and smooth non-imbricated scales, and other characters that do not indicate a close relationship with ischyra. Inopsetta ischyra resembles Isopsetta isolepis in the presence of rough scales on the median fins and in the lack of an arch in the lateral line, but

A CASE OF DRACONTIASIS IN PACIFIC COASTAL FISHES

Philometra americana n.sp., a dracunculoid nematode, appears to be common in several Pacific shallow water fishes; in Platichthys stellatus and Lepidopsetta bilineata in the dorsal and ventral fins or subcutaneously in the opercular region and gill cavity in Epigeichthys atropurpureus and Pholis ornatus always in the head region; and in Caularchus maeandricus in the lateral walls of the body.