Seasonal distribution and some features of the biology of spiny lumpfish <Emphasis Type="Italic">Eumicrotremus asperrimus</Emphasis> (Cyclopteridae,Scorpaeniformes) in the northwestern part of the Sea of Japan

According to data of 1981–2007, it was shown that the migration of spiny lumpfish Eumicrotremus asperrimus from wintering grounds to the coast begins in spring, with the onset of water warming. During summer and autumn, E. asperrinus feeds, concentrating in the bathymetric range of 100–300 m. With the start of winter water cooling, it migrates for wintering to depths larger than 500 m. Main aggregations of E. asperrimus were found off the coasts of Northern Primorye. Catches included specimens with a length of 3–16 cm; however, the overwhelming majority (95%) had a length of 5–10 cm, with the domination of two size groups: 6–7 and 9 cm. The spawning of E. asperrimus is apparently highly extended in time and occurs in the spring-summer period in shallow waters. Similarly to other representatives of the genus Eumicrotremus, E. asperrimus is a planktonphage with a narrow food specialization. Off the coasts of Primorye, in the summer period it feeds almost on one species—hyperiid Themisto japonica—with a value of diurnal diet averaging 6.7% of the body weight. According to an expert estimate, the biomass of E. asperrimus in the northwestern part of the Sea of Japan may comprise no less than 5000 t.     

Some aspects of the biology of the goblin shark, <Emphasis Type="Italic">Mitsukurina owstoni</Emphasis>, collected from the Tokyo Submarine Canyon and adjacent waters,Japan

A total of 148 specimens of Mitsukurina owstoni were examined for morphology, distribution, stomach contents, and reproductive condition. Sixty-nine males (81.7–208.5 cm in total length, TL) and 56 females (92.8–196.1 cm TL) were collected with bottom gillnets along a steep slope of the Tokyo Submarine Canyon (100–350 m depth) from May 1995 to October 1996. In addition, data were obtained from 23 specimens of M. owstoni collected from Sagami Bay, Suruga Bay, and the Enshu-nada Sea from 1972 to 2001. Japanese catch records already published (from 1898) plus those in the present study were from the Pacific coast of Japan, from Choshi to the Kii Peninsula. The main fishing season for M. owstoni by bottom gillnet fishing in the Tokyo Submarine Canyon was October to April, at depths of 200–245 m. No specimens examined were sexually mature, including the largest male (208.5 cm TL) and female (196.1 cm TL) recorded. Of 110 stomachs from specimens from the Tokyo Submarine Canyon, 32 (29.1%) were empty. The remainder variously included teleost fishes, squids, decapods, isopods, digested food, and human refuse. Teleost fishes (Macrouridae sp. and Stomiidae spp.), an isopod (Cymothoidae), and decapods (Pasiphaea sinensis and Sergia sp.) were the only identifiable prey, the indication being that teleosts (all size ranges) were of primary importance as prey for M. owstoni.     

Reproductive biology of the bigeye thresher shark,Alopias superciliosus (Lowe, 1839) (Chondrichthyes: Alopiidae), in the northwestern Pacific

Reproductive aspects ofAlopias superciliosus in the northwestern Pacific were described in detail, on the basis of 629 specimens (429 females and 200 males) collected from January 1984 to October 1984 and from October 1992 to March 1994.Alopias superciliosus embryos are oophagous. Six developmental stages (3 encapsulative and 3 posthatching) based on embryonic morphology and source of nutrition were recognized. The species bears 2 embryos per litter, their size at birth being between 135 and 140 cm TL. The sex ratio of embryos was 1∶1. Total length of females at maturity was 332–341. 1. cm; of males 270.1–287.6 cm. The gestation period could not be determined because most adult females were pregnant throughout the year. The typical reproductive strategy ofA. superciliosus is the production of a few large embryos per litter, with no fixed mating or birthing season.     

Sexual dimorphism in <Emphasis Type="Italic">Sebastes owstoni</Emphasis> (Scorpaenidae) from the Sea of Japan

Morphological and genetic differences between red and yellow morphotypes of Sebastes owstoni were investigated, utilizing 277 males [84.0–194.3 mm in standard length (SL)] and 542 females (92.3–251.5 mm SL) from the Sea of Japan. All males smaller than 120 mm SL were characterized by red body color. The frequency of specimens with yellow body color thereafter increased gradually with SL, all specimens larger than 170 mm SL being yellow. The specimens with yellow body color were observed throughout the year. All females smaller than 170 mm SL were characterized by red body color, the frequency of specimens with yellow body color tending to slightly increase with SL. However, most females had red body color, except for 16 specimens (177.7–241.5 mm SL) that were yellow, growth-related color change from red to yellow being uncommon. Morphological analysis of 49 males (107.6–193.3 mm SL) and 68 females (108.7–241.5 mm SL) showed the head length, orbit diameter, lower jaw length, and predorsal length to be relatively greater, but the distance between the pelvic and anal fins less, in males. A discriminant analysis using Mahalanobis distances resulted in 100% correct assignment of specimens to sex, regardless of SL and body color. In addition, no genetic differences were apparent between red and yellow individuals in mitochondrial DNA sequence analyses from the threonine tRNA to the first half of the control region (498 bp). Accordingly, the differences in body color, maximum size, and the five morphometric characters listed above were considered to represent sexual dimorphism. That evidenced by body color was considered to appear after that shown by morphometric characters, some exceptions in the former occurring in females. This is the first report of permanent sexual dimorphism in body color in Sebastes.     

Age and growth of ocellated icefish, Chionodraco rastrospinosus DeWitt and Hureau, 1979, from the South Shetland Islands

Age and growth of ocellated icefish, Chionodraco rastrospinosus, were investigated using counts of annual growth increments from sagittal otoliths. Samples were collected during research surveys by benthic trawl carried out around Elephant and South Shetland Islands in January–February 2002 and December 2006–January 2007. A total of 290 specimens were selected for the study, consisting of 120 females and 170 males. The age of fish was estimated by counting annuli on transverse sections obtained by grinding and polishing whole otoliths embedded in epoxy resin. The precision-of-age estimates within and between readers were tested applying both the average percent error (APE) and the coefficient of variation (CV). The estimated age-range was 1–12 for both sexes of C. rastrospinosus. Applying the von Bertalanffy growth function to the age–length data, a growth curve was obtained for each sex. The estimated values of VB growth parameters L _∞ and k were, respectively, 47.9 cm and 0.28 for females and 42.9 cm and 0.36 for males. Compared to other congeneric species, the growth performance of C. rastrospinosus was relatively high, being 2.82 and 2.81 in males and females, respectively. Age at sexual maturity was estimated to be about 4 years in both sexes. C. rastrospinosus captured in the studied area consisted mainly of adult specimens between 3 and 8 years, with few older fish.     

New data on sexual dimorphism and reproductive biology of Alaska skate <Emphasis Type="Italic">Bathyraja parmifera</Emphasis> from the northwestern Pacific Ocean

New data on sexual dimorphism and features of reproductive biology of Alaska skate Bathyraja parmifera from the western Bering Sea and the northern Sea of Okhotsk are presented. Based on comparative analysis of 11 external morphological characters, the males differ from the females in the length of the disc and snout length (to the eyes, to the mouth, and to the nostrils). In the western Bering Sea, 50% of the females and 50% of the males reach the first sexual maturity at 84.5 cm TL and 85.2–90.2 cm TL, respectively; in the Sea of Okhotsk, 50% of the males reach their first sexual maturity at 80.8–83.8 cm TL (the assessment depends on the features of the method). Among smaller skates (less than 45 cm TL), the males prevail, but the proportion of the females increases in larger size groups; the sex ratio becomes equal in the exemplars 60–80 cm TL, but the males prevail again among the largest fishes (more than 80 cm TL).     

New data on the reproductive biology of shortspine thornyhead <Emphasis Type="Italic">Sebastolobus alascanus</Emphasis> (Sebastidae) in the northwestern Pacific

New data on fecundity, sex ratio in different size groups, and the rate of sexual maturation of shortspine thornyhead Sebastolobus alascanus in the northwestern part of the Pacific Ocean are provided. Individual absolute fecundity of the studied females varies in the range of 175 000–821000 (on average, 392500) eggs. In Pacific waters off the Kuril Islands and Kamchatka, among individuals with a length to 41 cm, males dominate; in size groups of 42–59 cm, sex ratio is almost equal; among larger fish, females prevail. In the western part of the Bering Sea among analyzed fish with a length to 44 cm, sex ratio is almost equal; among larger individuals, females dominate. Half of males and females of shortspine thornyhead off the eastern coast of the northern Kuril Islands and southeastern Kamchatka mature at a length of approximately 41 cm that can be recommended as a commercial size for the given species in this area.     

Age,growth and reproductive biology of the silky shark,Carcharhinus falciformis,and the scalloped hammerhead,Sphyrna lewini,from the northwestern Gulf of Mexico

Synopsis The silky shark, Carcharhinus falciformis, and scalloped hammerhead, Sphyrna lewini, represent >80% of the shark by-catch of the winter swordfish/tuna longline fishery of the northwestern Gulf of Mexico. This catch represents a potential supplemental fishery, yet little is known of the life histories of the two species. This report relates reproductive biology data to age and growth estimates for 135 C. falciformis and 78 S. lewini. Unlike other regional populations, C. falciformis in the Gulf of Mexico may have a seasonal 12 month gestation period. Males mature at 210–220 cm TL (6–7 yr); females at >225 cm TL (7–9 yr). Application of age at length data for combined sexes produced von Bertalanffy growth model parameter estimates of L_∞ = 291 cm TL, K = 0.153, t₀ = −2.2 yr. Adult male S. lewini outnumbered adult females in catches because of differences in the distributions of the sexually segregated population. Males mature at 180 cm TL (10 yr); females at 250 cm TL (15 yr). von Bertalanffy parameter estimates for combined sexes of this species were L_∞ = 329 cm TL, K = 0.073, t_o = −2.2 yr.     

Recruitment of stock of deepwater redfish <Emphasis Type="Italic">Sebastes mentella</Emphasis> (Scorpaeniformes,Scorpaenidae) in the pelagial of the Irminger Sea and adjacent waters

Results of comparative analysis of several ecologo-populational characteristics and fauna of parasites of deepwater redfish Sebastes mentella from the pelagial of the Irminger Sea and slopes of Greenland are provided. It was established that the nursery area of the species in this part of the northern Atlantic is located in the shelf and shallow-water sites of the Greenland slopes. Near the nursery area, at deepwater sites of the Greenland slope, aggregations of mainly immature specimens (68–86%) with an average length of 35–38 cm are located, and, in the oceanic pelagial, there are mainly mature specimens (91–95%) with a length of more than 30 cm. Considerable similarity and specific features of fauna of parasites of S. mentella from the southeastern slope of Greenland and the pelagial of the Irminger Sea indicate the belonging of fish aggregations in these areas to a single intraspecies group and the migration of maturing specimens from the slope to the pelagial. A conclusion is made that the aggregations of S. mentella in the pelagial of the Irminger and Labrador seas represent a pelagic ecological group formed by rapidly maturing specimens; a near-bottom ecological group at deepwater sites of the slope of Greenland is formed by slowly maturing specimens. No mass migration of the redfish from deepwater areas to shallow sites of the slope and to the oceanic pelagial of the northern Atlantic was recorded.     

Age and growth of spiny dogfish <Emphasis Type="Italic">Squalus acanthias</Emphasis> (Squalidae,Chondrichthyes) in pacific waters off the Kuril Islands

On the basis of materials collected from catches of drift salmon nets in Pacific waters off the Kuril Islands from 2005 to 2006, the age and rate of growth of spiny dogfish Squalus acanthias are considered. Individuals with a length of 67–123 cm and weight of 1140–5970 g aged 10–26 years were represented in catches. In almost all age classes, the length of males was greater and the weight smaller than in females. The lifespan of females is slightly higher as compared to males-26 and 25 years, respectively. The values of K coefficient of the Bertallanffi equation of growth in males and females comprised 0.10 and 0.05 and the calculated values of the asymptotic body length comprised 116.3 cm and 147.2 cm. A relationship was found between the age of spiny dogfish and the spine size: its length (r _s = 0.693), base width (r _s = 0.815), and base length (r _s = 0.823).     

On occurrence and biology of Berg wrymouth <Emphasis Type="Italic">Cryptacanthodes bergi</Emphasis> (Cryptacanthodidae) in the north-western part of the Sea of Japan

With consideration of the data obtained in the period from 1981 to 2009, the occurrence of Berg wrymouth Cryptacanthodes bergi is estimated in the north-western part of the Sea of Japan. Almost all captures of wrymouth were made in Peter the Great Bay (only once was it caught in the Northern Primor’e) in a bathymetric range 18–60 m. Captures of Berg wrymouth are confined to aleurite bottom sediments. The size of captured specimens varied from 11 to 29 cm. The ratio of males and females in collections was close to 8: 1. In July–September, the gonads of females were at maturity stages III and IV and gonadosomatic index varied from 3 to 14%; in males, gonads were at stages II–III and III and gonadosomatic index varied from 0.5–2.7%, respectively.     

On reproduction of longfin thornyhead <Emphasis Type="Italic">Sebastolobus macrochir</Emphasis> (Scorpaeniformes: Sebastidae) in waters off the eastern coast of the Kurils

According to data obtained off the eastern coast of the Northern Kurils in October–December 1998, the body length of spawning females of the longfin thornyhead Sebastolobus macrochir is 26–41 cm (on average, 31.5 ± 0.27). Mass spawning is recorded in females 28 cm in length and longer. The individual absolute fecundity of females is 69355-411710 (on average, 189086 ± 13662) eggs. The reproductive potential of females of the longfin thornyhead is estimated as 189 million eggs. It is supposed that all females participate in spawning.     

Reproductive biology of the greyfin croaker <Emphasis Type="Italic">Pennahia anea</Emphasis> in the northern South China Sea

The greyfin croaker Pennahia anea is one of the most common croakers currently on retail sale in Hong Kong, but there are no regional studies on its biology or fishery. The reproductive biology of the species, based on 464 individuals obtained from local wet markets, was studied over 16 months (January 2008–April 2009) using gonadosomatic index (GSI) and gonad histology. Sizes used in this study ranged from 8.0 to 19.0 cm in standard length (SL). Both the larger and smaller size classes were missing from samples, implying that they are infrequently caught in the fishery. Based on GSI data, the approximate minimum sizes for male and female maturation were 12 cm SL. The size at 50% maturity for females was 14.3 cm SL, while all males in the samples were mature. Both GSI and gonad histology suggest that spawning activity occurred from March–April to June, with a peak in May. Since large croakers are declining in the local and regional fisheries, small species such as P. anea are becoming important, although they are mostly taken as bycatch. In view of unmanaged fishing pressure, and given the decline in large croakers and sizes of P. anea presently caught, proper management of the species is suggested.     

Reproductive biology of Bigeye Tuna, <Emphasis Type="Italic">Thunnus obesus</Emphasis>, (Scombridae) in the eastern and central tropical Pacific Ocean

Understanding the reproductive potential of any species is of great importance for resource assessment and management. We studied the reproductive biology of Bigeye Tuna, Thunnus obesus, based on 1283 samples taken from the Chinese longline vessels in the eastern and central Tropical Pacific Ocean during February through November 2006. The female-male ratio was 1.0 : 1.5 and males were predominant in all length classes except for the length class of 166–170 cm (fork length). Males dominated in sizes larger than 171 cm, all specimens of 192 cm or larger were males. The main spawning period of Bigeye Tuna was between March and November. Gonadosomatic rates of males were larger than those of females. Statistically, female and male Bigeye Tuna had no significant reproductive seasonality. The observed minimum length at sexual maturity for female Bigeye Tuna was 94 cm. Length at 50% sexual maturity of female Bigeye Tuna was estimated at 107.8 cm, and maturation rate was 0.106 cm⁻¹. The results derived in this study provide the information critical to our understanding of key life history parameters of Bigeye Tuna in tropic Pacific Ocean.     

A new species of deepwater cardinalfish, <Emphasis Type="Italic">Epigonus mayeri</Emphasis>, from the eastern Central Atlantic,and redescription of <Emphasis Type="Italic">Epigonus heracleus</Emphasis> Parin and Abramov 1986 (Perciformes: Epigonidae)

A new epigonid fish, Epigonus mayeri, is described on the basis of two specimens (109.7–113.8 mm in standard length: SL) from off Angola, and Epigonus heracleus Parin and Abramov 1986 is redescribed on the basis of 12 additional specimens with type specimens from off eastern New Zealand. These species belong to a subgroup of Epigonus, known as the “Epigonus robustus group,” which have a pungent opercular spine and VII-I, 9 dorsal-fin rays. The new species differs from other species of the group by having a sharp-pointed mustache-like process, presence of a rib on the last abdominal vertebra, vertebrae 10 + 15, tongue toothless, pyloric caeca 5, pectoral fin reaching to vertical line from anus (length 22.2–23.6% SL), orbital diameter 16.4–17.0% SL, head length 37.8–38.0% SL, and lower jaw length 16.7–17.0% SL.     

New data on biology of the pearlfish <Emphasis Type="Italic">Maurolicus imperatorius</Emphasis> (Sternopthychidae) from the Emperor Seamount Chain

The pearlfish Maurolicus imperatorius occurs above seamounts of the Emperor Seamount Chain between 30°–40° N and 168°–176° E. It forms dense aggregations at the daytime in the upper mesopelagial above the ground and disperses in the dark period of the day in the surficial layer. Judged by maturation dynamics of gonads, the spawning of this species occurs from January until April with the maximum in March. Catches of this species are characterized by expressed seasonal dynamics of size composition. Juveniles appear in catches in the end of spring-the beginning of summer. The maximum recorded SL is 68 mm. Among large fish, females dominate. The part of females is maximum in winter and minimum in spring. The age of fish with AC 46–63 mm is 265–420 days. The growth rate is abruptly retarded at the fourth month of life when the length 40–45 mm is attained. Life duration of most fish does not exceed 1.5 years, though some specimens may attain the age of two years. It is supposed that the presence of another species—M. japonicus—on the Emperor Seamount Chain may result from passive transfer in the Kuroshio waters.     

Aspects of body size and gonadal histology in the Antarctic toothfish, Dissostichus mawsoni, from McMurdo Sound, Antarctica

Twenty-eight specimens of the large notothenioid Dissostichus mawsoni were dissected after capture on a set line near the southern limit of its range in McMurdo Sound, Antarctica. Total length (L _T) averaged 127.3 cm (range 90–162 cm) and weight (W ) was 26.7 kg (range 10.4–60.3 kg). The length-weight relationship was W=3.44×10⁻⁵ L _T ^2.85 (n=28, r ²=0.96). Subcutaneous lipid thickness averaged 2.6 mm and showed no difference due to sex, but a significant weak relationship to W and L _T. Hepatosomatic index (I _H) was 1.6% for females and 1.7% for males; gonadosomatic index (I _G) was 0.9% for females and 0.2% for males. Although specimens were large and sexually mature, the histology indicated that the gonads of this November sample were in a resting stage. Testes lacked spermatids and spermatozoa. Oocytes were in the previtellogenic stage (91.2%) or in the first stage of vitellogenesis (8.8%). A few atretic oocytes and empty follicles indicated that some females in this sample had spawned previously. A summary of the life-cycle is also presented. Accepted: 27 September 1999     

A biological sampling problem illustrated by the population structure and growth patterns of Sardinella aurita at Tripoli,Libya

Synopsis Sardinella aurita were sampled from catches of the lampara fishery at Tripoli, Libya during October 1979 through to September 1980. Landings consisted mainly of adult fish with large (mode 21–26 cm total length), relatively fast growing 3–5-group individuals in winter and spring and smaller (mode 14–20 cm total length), slow growing 2- and 3-group fish in summer. Gonad growth commenced in April, when the fish were feeding on zooplankton, and continued at the expense of mesenteric fat until July. It is suggested that the older and bigger fish spawn first, probably after having moved westwards, and that this results in spatial and temporal differences in length at age within the population. There was no consistent difference in growth rate between the sexes, but because first maturity in males tends to occur earlier than in females, there were length distribution differences between the sexes in the youngest (2+) age group as sampled.     

Scramble Competition Among <Emphasis Type="Italic">Colobus vellerosus</Emphasis> at Boabeng-Fiema,Ghana

We investigated the occurrence of scramble competition among Colobus vellerosus at Boabeng-Fiema, Ghana. If scramble competition had an impact on feeding efficiency among females, we expected a positive relationship between group size and the proportion of time spent feeding, day journey length, or home range size assuming resource availability is similar among the groups compared. We collected focal data on the feeding behavior of adult females and males over 11 mo (September 2000–August 2001) on 2 study groups: WW (n = 31–33 individuals) and B (n = 8–16 individuals). We also collected ranging data on group movements at half-hour intervals. The large group (WW1) had a significantly longer day journey length than the small group (B1), and females in the large group spent a significantly greater proportion of time feeding in the wet season, a period of low food availability, which suggests it may be a bottleneck period when food resources are scarce and Colobus vellerosus is close to being energy limited. The proximity data suggested females may be able to reduce or adjust for competition by having fewer neighbors when they feed and by spreading out when in a larger group. However, we found no relationship between home range size and group size or that females spent a greater proportion of time feeding than adult males did. Our results highlight the need to factor in differences in food availability when investigating scramble competition. Though equivocal, our results suggest scramble competition occurs among Colobus vellerosus, leading us to suggest there was a match with the potential competitive regime, i.e., food distribution.     

Length-based growth,maturity and natural mortality of the cockfish <Emphasis Type="Italic">Callorhinchus callorhynchus</Emphasis> (Linnaeus, 1758) off Coquimbo,Chile

The growth rate, reproductive aspects, and natural mortality of chimaeras and ratfish are poorly known. In this study, life-history parameters for cockfish Callorhinchus callorhynchus (Holocephali—Callorhinchidae) are estimated, which is an important fish resource exploited in Chile. Specimens were sampled from the artisanal fishery captures, from November 2006 to November 2007. The standard length (SL) of males fluctuated between 20 and 62 cm, and between 21 and 70 cm for females. Von Bertalanffy growth parameters were estimated through length-frequency data analysis using MULTIFAN. The length-weight relationship and von Bertalanffy growth parameters were significantly different for males and females, as well as the length at 50% maturity. For males a model with 5 age-classes was the best, with asymptotic length L _∞ = 52 cm SL, growth coefficient K = 0.473 yr⁻¹, and age at length zero t ₀ = −0.690 yrs. For females the best model was represented by 10 age-classes (L _∞ = 70.3 cm SL, K = 0.193 yr⁻¹, t ₀ = −1.158 yrs) in the length-frequency data sets. Length at 50% maturity of males was estimated in 43.7 cm SL, and in 50.2 cm SL for females. The natural mortality rate fluctuated between 0.42 and 0.82 yr⁻¹ for males and between 0.12 and 0.37 yr⁻¹ for females, depending upon the method used. It is concluded that C. callorhynchus is a species with life-history parameters significantly different between males and females, and such differences should be taken into account in future population dynamics analysis.