Anal Length Research Articles

In situ target-strength measurement of young hairtail (Trichiurus haumela) in the Yellow Sea

Abstract The target strength of hairtail (Trichiurus haumela) in the Yellow Sea was measured in situ with a 38 kHz, split-beam echosounder on 2 January 2001. The fish measured were of the 2000 year class, its anal length ranged from 62 to 115 mm, with a mean of 89.8 mm. The mean target strength of these young hairtail was estimated to be −49.2 dB, with a 95% confidence interval of (−49.4, −49.0) dB. This provided a rare and useful reference for the acoustic-abundance estimation of hairtail.

Description of a new species of Armandia (Polychaeta: Opheliidae) from western Kyushu, Japan, with character variations

Armandia amakusaensis sp. nov. (Polychaeta: Opheliidae) is described from an intertidal sandflat in western Kyushu, Japan. The holotype measures 13.14 mm in total body length, and has 32 setigers, with branchiae on setigers 2–31. Eleven pairs of lateral eyes are present on setigers 7–17. The anal funnel opens dorsally, fringed with 11 papillae, its length being slightly shorter than the length of the last three setigers. A long unpaired cirrus originates mid-ventrally from the inside of the anal funnel. Variation in these diagnostic characters is described. The new species is most similar to A. leptocirris (Grube, 1878) and A. intermedia Fauvel, 1902. However, it is distinguished from A. leptocirris in the distribution patterns of the branchiae and the lateral eyes, and from A. intermedia in the distribution pattern of the lateral eyes, the ratio of anal funnel length to total body length, and the number of anal-funnel papillae.

スギマルカイガラムシにみられる寄主に関連した形態学的差異 ＩＩ．非寄主（スギ）で発育したカヤレースの形態

Our previous work showed that Cryptomeria japonica D. DON feeders and Torreya nucifera SIEB. et ZUCC. feeders of Aspidiotus cryptomeriae KUWANA are separate host races due to distinct morphological characters and virtually monophagous feeding habits. However, in the present work some A. cryptomeriae crawlers of the T. nucifera feeding race, which had been experimentally transferred to the non-host plant, C. japonica, grew to adults. The morphological characters of the C. japonica (non host) feeding T. nucifera race of A. cryptomeriae females were compared to those of the T. nucifera feeding T. nucifera race to examine whether the host plant had any effect on morphological characters. The two populations of A. cryptomeriae were reared under the same conditions except for the host plant. There were no significant differences between them for five morphological characters (p>0.05, t-test) except for pygidium length. Linear discriminant analysis using two characters (anal location and dorsal macroduct length) showed that the T. nucifera feeding race reared on C. japonica kept their normal morphological characters. Furthermore, eggs layed on the non-host plant by the adult A. cryptomeriae females reared on the non-host plant did not hatch. These results strongly suggest that the T. nucifera feeding race has very stable morphology that is not affected by the host plant. Even when A. cryptomeriae crawlers develop to the adult stage on non-host plants, they may not reproduce the next generation.

若狭湾西部海域におけるタチウオの漁業生物学的研究 ＶＩ 若狭湾西部海域におけるタチウオの年齢と成長

Favourite preys for ribbon fish Trichiurus lepturus (1.9-397.0mm in anal length) were described, based upon the progressive changes in the gut contents with growth. 512 ribbon fish were caught by larva net, beach seine, beam trawl, set net, purse seine, gill net and Danish seine during the years from 1980 to 1983 in the western Wakasa Bay. The occurrence method and the number method were used in the analysis of the food habit of the fish.The ribbon fish of less than 20mm in anal length was zooplankton feeder. The food habit of the fish 20-100mm length was carnivorous and the main foods of the fish were Natantia, Mysidacea and Pisces (mainly anchovy larvae). The fish of more than 100mm length had the piscivorous food habit and the main foods were anchovy and sardine.A particular size of the ribbon fish, which started feeding on other fishes in the western Wakasa Bay, was smaller than that of the East and Yellow China Sea, the adjacent waters of Tsushima and Osaka Bay. In common with each area, however, the fish of more than 250mm in anal length had the piscivorous food habit.The ribbon fish even at the early post larval stage had high feeding ability and positively fed on copepods such as Paracalanus parvus and Paracalanus sp., while the foods of 8 species at the same stage appeared in the same survey area were phytoplankton, nauplii and copepodites. This ability of the post larval ribbon fish seemed to be closely related to larger size of the egg and the larvae hatched than those of 8 species. Because the ribbon fish spawned smaller number of eggs than those of 8 species, the high ability of feeding at the early post larval stage is very important for their effective survival.The main gut contents of the fish of less than 10mm in anal length were pelagic copepods such as Paracalanus parvus, Paracalanus sp. and Clausocalanus sp. and 10-20mm length were females of Acartia erythraea which made swarms and generally occurred on or slightly above the bottom near the shore. The change of the main food from the pelagic copepods to the epibenthic copepod suggested that the ribbon fish of 10-20mm in anal length shifted their habitats from offshore to the bottom layer near the shore.

Anal and Neorectal Function after Ileal Pouch-Anal Anastomosis

Bowel function varies markedly among patients with colectomy and ileal pouch-anal anastomosis. Little is known of the mechanisms controlling fecal continence and frequency of defecation after operation. The aim of this study was to determine which features of the anal sphincter and neorectum accounted for the variation in clinical outcome. Twenty patients were studied 4 to 35 months after operation and compared to 12 healthy volunteers. Despite several patients exhibiting impaired fecal continence, anal sphincteric length and pressures and ileal pouch capacity and distensibility were similar in patients and controls. Patients with poor results, however, had rapid filling of their ileal pouch, which resulted in early onset of high amplitude propulsive pressure waves in the pouch. As these waves became more frequent, defecation resulted. Patients with poor results also were not able to empty adequately their pouch. The poorer the completeness of evacuation, the more frequent the defecation (r = 0.62, p less than 0.01). The authors conclude that rapid pouch filling and impaired pouch evacuation can lead to increased stool frequency in patients after ileal pouch-anal anastomosis.

若狭湾西部海域におけるタチウオの漁業生物学的研究 ＩＩ 若狭湾西部海域におけるタチウオの産卵期と性比

This paper deals with the spawning season and sex ration of ribbon fish Trichiurus lepturus in the western Warasa Bay from June, 1981 to February, 1983, which were caught by longline, trolling, set net, purse seine and Danish seine. It was found that the spawning season was from June to September and the highest value fo gonad index of both sexes were shown from July to August. In the early spawning season. maturation of gonad was found in large sized fish more than 300 mm of anal length, and maturation made progress in orde of size. Just before the spawning season, schools of larger fish with the sexratio 1 : 1appeared in this area. In the spawning season. females and males dominated the near shore and offshore, respectively. It was suggested that the difference in the distribution of the sexes was concerned with the mating system.

A neotype for Eucephalobus striatus (Bastian, 1865) Thorne, 1937 (Nematoda) and redescription of the species from topotypes and their progeny.

The dimensions and morphology of the progeny of five female topotypes of Eucephalobus striatus cultures on agar ranged more widely than in previous descriptions. Specimens from agar were usually longer and wider than topotypes from soil, had shorter tails of more variable shape, a smaller anal body width-tail length ratio, the ovary was often not flexed, and the deirids and excretory pore were usually more posterior. First-generation larvae developed slowly on agar, requiring at least a month to become adult. Adult females from agar were devoid of sperms and did not usually reproduce, and their gonads differed from those of impregnated, fecund specimens from soil. The bifurcate labial probolae and duplex lips in all specimens and the variability of the female tail showed that they were close to Cephalobus persegnis Bastian, 1865. Length and shape of the postuterine sac, length of the gubernaculum compared with spicule length, and the position where the incisures ended on the female tail were the most reliable characters for species identification but of doubtful generic value. Differences in the stoma, including an undescribed region between the cheilostom and prostom, are discussed and illustrated.

マアナゴの生態学的研究-I

In the Seto Inland Sea the conger eel, Astroconger myriaster (Brevoort) is a commercially important species to be caught by small sized trawlers. In the present work, growth of the fish has been studied on the basis of morphometric surveys conducted during 1952-56 for 1, 960 individuals from fishing grounds off Marugame and 1, 892 off Takuma (Table 1 and Fig. 1). 1) Frequency distribution of the anal length composition and seasonal changes in the modes (Figs. 2 and 3) have suggested that the fish under study consist of two major age groups: the young exploited during August to December and the older staying in the areas over the year. The field data indicated the average growth from summer to summer to be about 50mm. 2) Relation between total length (L) and anal length (l) of 400 specimens collected in 1956 may be expressed as L=14.38+2.45l. From the anal length composition obtained at Marugame during 1952-56, the mean anal length of the young and the older groups was separately computed for the coordinate months of the years (Table 3). The results revealed that the annual growth averages 50mm. in a close agreement with the one determined from the field data. However, the young group from Marugame was found a little different in the growth trend from that of Takuma (Fig. 4). The difference may be partly attributable to the particular topography of Takuma area where the tidal currents from the outer sea join each other and receed to different directions. According to the least square method, the growth of the conger eel in these areas may be formulated as follows: For the young group occurring during August to December l=73.143+2.150a (Marugame), logl=1.8327+0.1288logl (Takuma); For the older group occurring in early months of the following year l=110.464+1.484a (Marugame), l=105.133+1.851a (Takuma), where l is anal length and a is age by ten day period. 3) In the conger eel under report, relation between body weight (w) and anal length (l) is indicated as in Fig. 5 and by a formula log w=-5.8326+3.614 log l. Assuming that the fish complete their metamorphosis in a year after hatching, it is inferable that the conger eel in the areas are composed of the two-year-old and the three-year-old groups.

太平洋赤道水域産キハダの外部形態について

On the yellowfin tuna distributed in the tropical and subtropical zones of the Pacific, we made a biometrical analysis on the various morphological characters, so as to know that the fins Japanese tuna fleets are catching belong either to one population or not, based upon the specimens from 1953 to date. Samples used in this report are tabulated in Table 1, showing the origin, fishing date, number of fish, range and average of body length. All specimens were measured by the junior author at the Tokyo Central Fish Market. Measurements were made in millimeters using slide calipers and a pair of dividers in accordance with the techniques described by Marr and Schaefer (1949). Several samples of yellowfin tuna, Neothunnus macropterus, from the Equaforial Pacific ranging from 130° W to 130° E were compared on sixteen different body characters (Fig. 1) and the following results were obtained. 1) The specimens of yellowfin taken from the same area in different years show difference in maxillary length, anal length and spread caudal (Table 2). But generally we can say with certainty, they have considerably similar morphometrical characteristics. 2) It appears to be a much greater degree of separation between 170° W and 150° E and between 160° W and 130° W, than between 150° E and 130° E and between 170° W and 160° W (Table 3). 3) The specimens of yellowfin from the area of 160°W have shorter head, more anteriorly positioned ventral and pectoral fin than those form the eastward and westward regions (Table 4, Fig. 2). But for eye diameter, second dorsal and anal length, the measurement is the greatest in the Western Pacific ones and the least in the Eastern Pacific ones, and this tendency agrees with Royce's result (1953). 4) By the facts above mentioned, it is morphometrically probable that there would be at least three populations rather independently but with some mixing between each other.