Growth and age of staghorn sculpins of the genus <Emphasis Type="Italic">Gymnocanthus</Emphasis> (Cottidae) in Peter the Great Bay and adjacent waters of Primorye (Sea of Japan)

Age and growth have been studied in four species of staghorn sculpins of the genus Gymnocanthus inhabiting Primorye (the Russian sector of the Sea of Japan). Large black edged and purplegray sculpins, G. herzensteini and G. detrisus, inhabited deeper waters compared with threaded sculpin G. pistilliger and (especially) whip sculpin G. intermedius. The size differences between different sculpin species could already be revealed in the diameter of mature oocytes and the length of hatching larvae and fries passing to the benthic phase of development. The maximum size in these species correlated with their maximum age. G. herzensteini, G. detrisus, G. pistilliger, and G. intermedius could attain the age of no less than 16+, 15+, 9+, and 7+, respectively. The gains in fish of the same age were also greater in species attaining greater size values. In all the species, females lived longer than males and were larger than males of the same age. Throughout the life cycle, the growth rate gradually came down; the decrease was especially pronounced during the period of sexual maturation. In the southern part of the geographic range, the specimens of purplegray sculpin attained smaller size and showed lower growth rate compared with the fish from the northern part of the range. The threaded sculpin demonstrated the inverse relationships. In general, females were dominating in samples of staghorn sculpins; however in small and medium size groups, the proportion of males was greater, which was due to their smaller, compared with females, absolute gains. In elder groups, the proportion of males gradually went down, as they were dying earlier than females.     

Age and growth of Far Eastern staghorn sculpin <Emphasis Type="Italic">Ggymnocanthus herzensteini</Emphasis> (Cottidae) in peter the Great Bay (the Sea of Japan)

In a sample of Far Eastern staghorn sculpin Gymnocanthus herzensteini with a length up to 40 cm, age and growth were assessed from the results of analysis of thin longitudinal sections of otolith (sagitta). Males attained to an age not less than 13 years and females attained to an age not less than 17 years. Maximum length of males is much smaller than that of females. The absolute gains of females are greater than those of males; however, there are no considerable differences in the specific rate of growth. The most intensive growth is observed in the first two to three years of life. During sexual maturation, its rate decreases. The next noticeable decrease in the rate of growth occurs in fish of elder age groups. In catches of Far Eastern staghorn sculpin in Peter the Great Bay, females dominate; however, in groups of small and medium-sized individuals, the proportion of males increases, which is related to their smaller, as compared to females, absolute gains. The subsequent decrease in the proportion of large-sized males is determined by their greater natural mortality, as compared to similar-sized females.     

Validation of roughhead grenadier (Macrourus berglax) otolith reading

Roughhead grenadier Macrourus berglax Lacépède 1802, is becoming an important commercial fish in the north-west Atlantic fisheries and reliable age information is needed for its assessment. Macrourus berglax has been aged by counting otolith growth zones assumed to represent anulli. Three validation methods were applied: back-calculation of length-at-age, length–frequency analysis, and analyses of the progression of the length mode of an exceptionally large year class. Results on size-at-age estimated by otolith growth zone counts, length–frequency analysis of pre-anal fin length and modal progression were internally consistent, but estimates by back-calculation were different. This latter method produces unrealistic growth curves for each sex due to the weak relationship between otolith size as measured and pre-anal fin length. Up to age 8–9 the size-at-age were the same for males and females; thereafter males were smaller than females. Male growth rate declined when pre-anal fin length reached 18 cm at around age 9, whereas the growth of females started to decline at about 30 cm at around age 16. The Von Bertalanffy growth model derived from otolith analysis was similar to that obtained by the Multifan length frequency analysis model, and gave realistic values of L _inf, close to the maximum anal fin lengths found in catches. The results showed that Macrourus berglax has a prolonged life cycle and differences in growth between males and females.     

Summer distribution of the purplegray sculpin <Emphasis Type="Italic">Gymnocanthus detrisus</Emphasis> (Cottidae) in Waters of Primorsky Krai,Sea of Japan

Results of trawl catches show that in the summer period, in the waters of Primorsky Krai, Russia, Sea of Japan, the purplegray sculpin Gymnocanthus detrisus occurs at depths of 20 to 411 m, preferring the range 80–250 m. The temperature of the species’ habitat varies from 0.8 to 8.6 ° C, and the optimal one is 1.2–2.2 °C. G. detrisus occurs at the preferred depths more frequently in the southern area—the Peter the Great Bay, which is more favorable for foraging; in the area of North Primorsky Krai it was found both at greater and lesser depths. The latter is probably determined by the more limited spreading of waters with unsuitable temperatures for the species there. The body size of the purplegray sculpin grows with depth. Juveniles avoid depths over 200 m, where inflow of low-temperature waters is recorded. G. detrisus, which inhabits waters of Primorsky Krai, is represented mainly by females; the proportion of males exceeds that of females only in the 21–27 cm size group. This may be related to the lower growth rate in males after maturation as compared to females.     

Age determination, bomb-radiocarbon validation and growth of Atlantic halibut (Hippoglossus hippoglossus) from the Northwest Atlantic

Atlantic halibut (Hippoglossus hippoglossus) is the largest and one of the most widely-ranging and commercially-valuable groundfish in the Atlantic Ocean. Although presumed to be long-lived, their age and growth has not been validated. Ages were estimated by counting growth increments from approximately 2400 thin-sectioned sagittal otoliths collected from the Scotian Shelf and southern Grand Banks off eastern Canada. The accuracy of age estimates made from otolith thin sections was validated using bomb-radiocarbon assays of 13 otolith cores whose year of formation ranged from 1949 to 1975, encompassing the timeframe of the global radiocarbon pulse. Known-age juvenile halibut from a culture facility were used to identify the approximate location of the first annulus. Growth rate for males and females was similar up to about 70 cm (~5 years), after which point male growth slowed, while female growth continued to an age of up to 38 years and a maximum observed size of 232 cm. Males grew to an observed maximum length of about 175 cm and a maximum age of 50 years. A comparison of age estimates for otoliths collected in a ‘historic’ time frame (1963 to 1974) with those from recent years (1997 to 2007) shows that growth rate has not changed appreciably between the two time periods. Small but significant growth differences were observed between the Scotian Shelf and southern Grand Banks for both sexes, while large differences in length at age were observed between halibut caught with longline compared to otter trawl due to differences in length-based gear selectivity. Age interpretations based on sectioned otoliths tended to be 10–15% different than those based on break and burn, although the age comparison was confounded by other variables and must be considered provisional. Atlantic halibut is a long-lived fish, living up to at least 50 years, an important consideration for the management of the fishery.     

Reproductive biology and growth of bluestripe herring Herklotsichthys quadrimaculatus (Rüppell, 1837) in the northernmost waters

In order to examine the reproductive biology and growth of Herklotsichthys quadrimaculatus in the northernmost part of its reproductive range, the size frequency, gonadal development, and otolith daily increments of this species were collected from the coastal waters of Okinawa Island, southern Japan. Juveniles (<25 mm standard length, SL) were found from April to August. Their size increased to ca. 100 mm SL in November and subsequently remained unchanged. The gonadosomatic index of females was higher (>3.0) between March and August, which was the estimated spawning period. The modal hatching period back‐calculated from otolith daily increments was from April to May, which would be the peak of spawning. Because mature and spent ovaries also contained mature and immature oocytes, it was concluded that females spawn several times during the spawning season. Age determination from otolith increments showed logistic growth up to 97 mm (ca. 180 days post‐hatch), after which growth was almost stagnant. Maximum size and age were 121.6 mm SL and 384 days, respectively. The adult size decreased between August and September, indicating a change in the age cohort. Thus, the fish reached the end of their lifespans after spawning. Some of these ecological features were different from those of a previous study performed in southern areas; these differences suggest a flexible life history that could change to adapt to the surrounding environment.     

The distribution and some biological features of Stichaeus grigorjewi (Stichaeidae) in the waters of northern Primorye (The Sea of Japan)

Stichaeus grigorjewi is a common species, but in the waters of northern Primorye it is comparatively rare. It occurs at depths down to 465 m for the greater part of the year, except for the spawning period, staying in deep-water masses with relatively stable temperature conditions. The widest bathymetric distribution of S. grigorjewi is observed from spring-early summer. After the completition of spawning, it shifts to depths larger than 100 m and winters in the upper section of the continental slope. During each season maximum concentrations of S. grigorjewi along the coasts of Primorye are observed in water from Povorotnyi Cape to the Olga Gulf. Males and females of this species have close rates of growth and reach an age of not less than 12+ years. Most individuals of S. grigorjewi in catches had a length of 37 to 44 cm and fed mainly on fish.     

Age and Growth of Blue Antimora <Emphasis Type="Italic">Antimora rostrata</Emphasis> (Moridae) in Southwestern Greenland Waters

The results of determination of age and study on growth of blue antimora Antimora rostrata from the waters of Southwestern Greenland are presented. The results are based on the analysis of 200 fish otoliths. In the catches, we found specimens of antimora with total lengths of 18?70 cm, body weights of 23?2731 g, at the age of 7?38 years. Minimal age of males (not considering juvenile individuals) was 10 years at body length of 27?33 cm; maximal age was 18 years at 42 cm. Minimal age of females was 9 years at length of 21–27 cm; maximal age was 38 years at 70 cm. The rate of linear growth in blue antimora from Southwestern Greenland waters is comparable to that in the fish from New Zealand and Ross Sea waters but considerably lower than indicated earlier for fish from the waters of Iceland, Greenland, and the Mid-Atlantic Ridge. The age of reaching sexual maturity in males and females is preliminary determined as 15 and 19?20 years, respectively.     

Growth and reproduction of Chelidonichthys lucerna (Linnaeus) (Pisces: Triglidae) in the Gulf of Gabès,Tunisia

Growth and reproduction of Chelidonichthys lucerna is reported from Tunisian waters. A total of 286 specimens was collected from landings of bottom trawlers between January 2003 and November 2004. The total length ranged from 16 to 36 cm in females and from 17 to 26 cm in males. Marginal increment analysis of otoliths showed that the translucent zone was laid from October to May and the opaque zone laid from June to September. Females were from 0.5 to 9 years and males from 1 to 7 years old. Growth parameters of the von Bertalanffy growth function were TL_∞ = 40.26; K = 0.06 and t₀ = ?3.03 in females and TL_∞ = 46.16; K = 0.059 and t₀ = ?1.32 in males. The coefficient of the allometric length–weight relationships differed significantly by sex. Females with mature gonads were observed between October and May, with peaks in January and February. Length at which 50% of specimens were mature was 21.6 cm TL (estimated age about 3 years) in females and 19.2 cm TL (estimated age about 1.5 years) in males.     

Age and growth of Trisopterus luscus (Linnaeus, 1758) (Pisces,Gadidae) off the coast of Asturias

The age and growth of an Asturian population of the bib Trisopterus luscus L. were studied based on 990 bibs from monthly catches from October 1986 until October 1988.Using the estimates of age taken from otolith readings, it was possible to construct a growth curve for the whole range of ages and demonstrate that most growth takes place during the first two years of life. The maximum age was found to be 5 years. The largest fish caught during the investigation measured 430 mm in standard length.The different growth rates of males and females show that in most cases the mean standard length of females was equal to or greater than that of the males.     

Morphobiological features of the flathead sculpin Megalocottus platycephalus taeniopterus (Kner) (Scorpaeniformes, Cottidae) from Sakhalin

Data on the flathead sculpin Megalocottus platycephalus taeniopterus from different regions of Sakhalin are provided. Based on analysis of the morphological material, the estimates of taxonomically significant characters of the northern and southern subspecies are clarified. They include the relative length of the lower jaw, the extent of development of postorbital and occipital tubers, the coloration of pectoral fins, the shape of free ends of ventral fin rays, and their relative length and coloration in females. The habitats of M. platycephalus taeniopterus are considerably attributed to the desalinated sites of coastal waters. In the areas of eastern Sakhalin, its individuals stay in brackish water lakes and lagoons for a considerable part of their life; some individuals migrate to coastal waters for feeding in summer. Considerable differences are observed between populations in the life span, rate of growth, and the age of maturation of individuals. In the regions of eastern and western Sakhalin, the pattern of feeding of M. platycephalus taeniopterus differs considerably: in eastern regions, it is a clearly pronounced predator, and in western regions, it feeds mainly on invertebrates.     

Life history of harbor porpoises (Phocoena phocoena) in Scottish (UK) waters

Life history parameters were determined for stranded and bycaught harbor porpoises (Phocoena phocoena) from Scottish (UK) waters (1992–2005). Fetal growth rate was 84.4 mm/mo and mean size at birth was 76.4 cm (range 65–88 cm). Males and females had a similar range of body lengths (65–170 cm and 66–173 cm, respectively), although asymptotic lengths were higher in females than males (approximately 158 cm and 147 cm, respectively). Nonpregnant females were significantly lighter, in relation to their length than males. Maximum estimated age was 20 yr for both sexes. Age at sexual maturity (ASM) was estimated as 4.35 yr in females and 5.00 yr in males. Conception occurred mainly in July and August although reproductively active males were recorded during April to July. Gestation lasted 10–11 mo, with calving mainly between May and July. Lactating females were recorded during June to November, while small calves with solid food in their stomachs were found mainly during February to May. Estimated pregnancy rate (0.34–0.40) is lower than recorded elsewhere, but is likely underestimated due to the prevalence of mature females of poor health status in the sample. Nevertheless, cetacean strandings can be an essential source of data on demographic parameters.     

New information on age and growth in length of Micromesistius australis,Norman 1937 (Pisces,Gadidae), in the South-West Atlantic

Summary Sagittal otoliths were used for age determination in 1121 specimens of Micromesistius australis, caught in waters of the South-West Atlantic during the cruises made by the ships Walther Herwig and Shinkai Maru in agreement with the Argentine Republic, during the years 1978 and 1978/1979, respectively. The interpretation of growth rings required the otoliths to undergo a paraffin wax embedding and cutting technique. The relations otolith length-fish length and fish length-half otolith width were linear. Thus, back calculations, when necessary, were made by a simple extrapolation. Numbers of males and females were nearly equal, resulting in a sex ratio of 1:1.09. Length frequencies and age distributions were calculated for each sex separately. A significant difference in growth between sexes was found, curves for each were derived. A linear, regression was made and the Von Bertalanffy equation estimated as: Lt=56.90 [1-e^{-0.1983 (t+1.84)}], in males, and Lt=60.08 [1-e^{-0.1769 (t+2.07)}] in females, with Lt in cm and t in years. For estimation of these equation parameters age groups 2–16 years in males and 2–22 years in females were taken into account. All theoretical Lt values and almost all observed lengths for females were greater than those of males in corresponding age groups. Previously published observations about M. australis on this subject, are not in agreement or only in partial accord with present results. These are discussed. Original photographs of otolith cross sections illustrating age determination methods are presented for the first time in age and growth studies of this species.     

Seasonal variation of mass, condition and gonadosomatic index in fourhorn sculpin (Myoxocephalus quadricornis) with normal and malformed vertebrae in the Gulf of Bothnia

It may be expected that vertehral anomaties would reduer the viability and reproductive success of fish. In the present study. the relationship of vertebral defects to body mass. Iength, age, condition, gonadosomatic index and growth in fourhorn sculpin, Myoxocephalus quadricornis , in the Gulf of Bothnia was studied. There were no differences in growth between normal and defective lish, for either males or females. While normal and defectives males were similar in age and length. defective females were older and longer than normal females. Defective males and females had a significantly greater somatic mass that normal fish. However defective females may be later than in normal fish. Hence, vertebral defects do not necessarly reduce the reproductive potential of fourhorn sculpin.     

Seasonal Distribution of Antlered Sculpin, <Emphasis Type="Italic">Enophrys diceraus</Emphasis> (Cottidae) in Peter the Great Bay,Sea of Japan

The antlered sculpin Enophrys diceraus in Peter the Great Bay is found to inhabit from shallow waters to depths deeper than 600 m. The range of depth where this species occurs is the narrowest, from 12 to 250 m deep, in summer. The greatest depths of inhabitation are characteristic, in all seasons, only of adult fish of this species. In the cold period of the year, the young probably avoid the upper part of the shelf where the temperatures have cooled down to negative numbers. Spawning in the antlered sculpin begins in the second half of November. Females dominate the population of this species inhabiting Peter the Great Bay. Males reach 38 cm long and more; females can be up to 31 cm long. The greatest density of antlered sculpin in the summer period on the preferred substrates is observed in the western part of the bay, primarily on sandy ground.     

First data on the age,growth processes,and otoliths of snub-nosed spiny eel <Emphasis Type="Italic">Notacanthus chemnitzii</Emphasis> (Notacanthidae)

This is the first work on the age, developmental stages, and otoliths of snub-nosed spiny eel Notacanthus chemnitzii (Notacanthidae), a rare fish species inhabiting the waters of southwestern Greenland. The mean age of 14 studied fishes (with a length of 36–104 cm and a mass of 74–3834 g) varied in the range from 11 to 26 years. Since the duration of leptocephalus stage is unknown, the real age can be greater. The length of snub-nosed spiny eel can reach 122 cm; thus, its maximal age can be more than 30 years. The minimal length of mature females was 55 cm (18 years); the minimal length of mature males was 66 cm (14 years).     

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 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).     

Spawning,maturity, growth and movement of Platycephalus fuscus (Cuvier, 1829) (Platycephalidae): fishery management considerations

The dusky flathead (Platycephalus fuscus) is an important teleost harvested by recreational and commercial fishers throughout its endemic distribution along eastern Australia. This study indicates that the species has an extended spawning period throughout the austral summer, with females in spawning condition occurring in lower estuarine and coastal waters. Total length (L₅₀) and age (A₅₀) at which 50% (±1 SE) of the population was mature was 31.72 (±1.08) cm TL and 1.22 (±0.44) years for males and 56.75 (±0.60) cm TL and 4.55 (±0.13) years for females. The von Bertalanffy growth parameters differed significantly between sexes; females grew faster and attained a greater maximum TL and age than males. The largest female was 98.5 cm TL (7.5 kg), and the oldest 16 years, whereas the largest male was 61.5 cm TL (1.58 kg) and 11 years of age. A tag‐and‐release study identified the exchange of sub‐adult and mature‐sized individuals among estuaries. Determinations of length‐based management regulations for the species are compounded by the large gender‐based differences in growth and length‐at‐maturity. Current minimum legal lengths of 30–40 cm TL protect approximately 3–9% of the female spawning population. Alternative management options, including harvest slot sizes, need to be investigated and tested.     

Age and growth of the round goby Neogobius melanostomus in the Gulf of Gdańsk several years after invasion. Is the Baltic Sea a new Promised Land?

The ages of 8 to 23·5 cm total length (L(T)) round goby Neogobius melanostomus collected monthly during 2006 and 2007 in the Gulf of Gdańsk (Baltic Sea) ranged from 2 to 6 years, with age class 4+ years dominant. Males were larger at age than females. The fastest growth occurred in the first 2 years of life in both sexes. Females were heavier at a given L(T) than males, but only for fish > c. 15 cm. A strong relationship between N. melanostomus otolith size and fish size was found, with no difference between males and females, and a significant relationship between fish growth rate and otolith growth rate, which enabled backcalculation of growth rates. Marginal increment width analysis confirmed the periodicity of annual ring formation in otoliths and showed that the most intense opaque zone formation occurs in July to August, while hyaline zone formation starts as early as September to October. It was concluded that the N. melanostomus that have colonized the southern Baltic Sea exhibit the largest size and longest life span ever recorded for this species.