A skeletochronological study of age, growth and longevity in a population of the frog Rana ridibunda from southern Europe

Age at sexual maturity and longevity in a population of Rana ridibunda from north-eastern Greece were studied by skeletochronology performed on the phalanges. Analysis of the age structure was based on counting the lines of arrested growth (LAGs). Sexual maturity for both sexes arises during the first year or after the first hibernation. Ages ranged from 1 to 5 years (mean=2.96) among 52 males and from 1 to 5 years (mean=3.73) among 56 females. The mean snout-vent length was 69.03+/-12.6mm in males and 82.38+/-13.27 mm in females. The difference between the sexes in age and size was significant. Growth of individuals was fitted on? The von Bertalanffy model. The growth coefficient (K) was 0.57 in males and 0.54 in females, mainly due to faster male growth between metamorphosis and maturation.     

白鲟年龄鉴定及其生长的初步研究

以齿骨和胸鳍条为年龄鉴定材料,通过其骨磨片比较研究,结果显示用胸鳍条鉴定白鲟的年龄较为可靠。所收集的６６尾白鲟样品中,根据胸鳍条鉴定年龄,幼鲟８尾,１－３龄。成鱼５８尾中,雄鱼３３尾,最低６龄,最高１１龄,多数个体为８－９龄。雌鱼２５尾,最低７龄,最高１７龄,多数为１０－１２。白鲟生长速度快,特别在第一年其长度生长最为突出。当年１０月份的幼鱼全长达５３－６１ｃｍ,１龄鱼平均全长７５ｃｍ。推算结果表明雌雄鱼在性成熟前生长无明显差异,性成熟后,雌鱼的长度及重量均大于相同年龄雄鱼。采用ＶＢＧＦ描述白鲟全长及体重的增长。     

Life-history patterns of the mosquito-fish, Gambusia affinis, in the estuary of the Guadalquivir river of south-west Spain

SUMMARY. 1. The age, growth and reproduction of the small, introduced fish Gambusia affinis (Baird & Girard, 1853) were studied in the estuary of the Guadalquivir river.
2. The life-span was very short, the stock contained only two age groups: with annulus (1+ group; 10–12 months old) and without annulus (0+ group).
3. In both sexes growth restarted in April when the annulus appeared, but whilst 1+ males stopped growth, 1+ females grew steadily to June. Growth of 0+ spawners was only evident in September, the last month of the reproductive period. A differential growth rate between sexes was also evident.
4. 1+ specimens reproduced during May and June and their offspring from July to September. In both age groups somatic condition progressively declined during the spawning period.
5. The loss of condition and the disappearance of 1 + and the larger 04-specimens after reproduction may indicate the cost of a prolonged high level of reproductive effort.
6. The total fecundity (taken as the number of embryos) of 1 + females was represented by the formula: Fec=5.08 T.L. (mm) -170.07 and that of 0+ specimens by: Fec=2.23 T.L. (mm) -42.92. The maximum average monthly fecundity was reached in June when the length of the mother was at its greatest.
7. Length at first maturity was smaller in 0+ group than in the 1 + group; the difference between the two groups was greater in males (≅5 mm, T.L.) than in females (≅3 mm, T.L.). Also the average total length of 14-spawners was greater than 0+ spawners. There were significant differences in the overall sex ratio of 956 males to 2057 females.
8. The differences found in growth and reproduction between the two age groups suggest that life-history tactics may vary not only between different stocks but also within the same stock among its different components.     

Life history of the red-banded seabream Pagrus auriga (Sparidae) from the coasts of the Canarian archipelago

Red‐banded seabream Pagrus auriga (N = 615) were caught off the Canary Islands from January 2003 to December 2004. Total length ranged from 120 to 780 mm. The species was characterized by protogynous hermaphroditism. The male :female ratio was in favour of females (1 : 8.2). The reproductive season extended from September to February, with a peak in spawning activity in October–November. Fifty percentage maturity was reached at 387 mm total length by females and 533 mm by males. The length–weight relationship for all individuals was described by the parameters: a = 0.0086 and b = 3.014, when length is given in mm and weight in grams. Otolith age readings indicated that the population consists of 19 age groups, including a very high proportion of individuals between 0 and 7 years old. Growth analysis reveals that the species is slow‐growing and relatively long lived (18 years). The von Bertalanffy growth parameters for the entire population were: L_∞ = 803 mm, k = 0.081 year⁻¹ and t₀ = −2.17 year. Growth differed between males and females. The instantaneous rate of natural mortality for all fish was: M = 0.164 year⁻¹.     

Age estimation,growth and maturity of the Argentine hake (Merluccius hubbsi Marini, 1933) along the northernmost limit of its distribution in the south-western Atlantic

Age, growth and length-at-maturity of the Argentine hake (Merluccius hubbsi) were studied in the northernmost limit of the species distribution in the south-western Atlantic. A total of 351 otoliths and information from 1610 specimens sampled from the industrial double-rig trawl landings between May 2013 and April 2014 were used. Age and growth were estimated by counting and measuring increments in sectioned sagittae otoliths, and length at maturity was estimated based on macroscopic gonadal analysis. For both sexes, hepatosomatic index and condition index increased mainly during spring, reaching a maximum at the end of summer before the subsequent spawning season began. Gonadosomatic index was highest in April, believed to correspond with peak spawning. The annual periodicity of alternate opaque and translucent zones was validated by marginal increment analysis. Growth curves were fitted to back-calculated size at age by fitting the three-parameters von Bertalanffy growth function. The maximum age was 5 years in fish of either sex. Females attained larger sizes than males. The parameters of the von Bertalanffy growth equations were: L∞?=?533?mm, k?=?0.231 year^?1 and t₀?=??0.935 year for females; L∞?=?394?mm, k?=?0.405 year^?1 and t₀?=??0.463 year for males. The mean length and age at first maturity was 273?mm at 1.9 years for males and 274?mm at 2.0 years for females.     

Age and growth of the bonnethead shark, Sphyrna tiburo, from northwest Florida, with comments on clinal variation

Age and growth rates of the bonnethead shark, Sphyrna tiburo, from northwest Florida were estimated from vertebrae collected between October 1992 and October 1995. The von Bertalanffy growth equation was fit to male and female vertebral age data. Initial growth was rapid (≈ 200 mm TL) for both sexes from age 0–1. At age 2 growth slowed for males but continued for females. Similar to many species of sharks, females grew slower than males (K = 0.28 and K = 0.69, respectively) but attained a larger maximum size (L_∞=1226 and L_∞=897). Maximum age was estimated in males and females to be 8+ and 12+ years, respectively. Growth of young-of-year sharks was 21 to 30 mm TL per month determined by three different methods. A comparison of age and growth estimates from populations at more southerly latitudes suggest that clinal variation in total length may be evident among bonnethead sharks in the Gulf of Mexico with females reaching larger sizes in northern areas as compared to south Florida. This revised version was published online in July 2006 with corrections to the Cover Date.     

Composition, growth and conditionindex for a population of Poecilia reticulata (Pisces: Poeciliidae), in a pond in Heredia, Costa Rica

A pond population of Poecilia reticulata was studied in Santo Domingo, Heredia, Costa Rica, between September and November of 1998. The sex ratio was 1:0.49 (males:females). The mean total length was 34.43 +/- 7.26 mm for females, 23.50 +/- 2.24 mm for males and 12.27 +/- 3.41 mm for juveniles. The mean total weight was 0.69 +/- 0.48 g for females: and 0.16 +/- 0.05 g for males and 0.026 +/- 0.027 g for juveniles. The total length-weight relationship for the total population was P= 6 x 10(-5) Lt 3.3272 (r2 = 0.9613). The condition index equation was K = 25.755 e(0.004Lt) (r2 = 0.8925) for females and K = 26.767 e(0.003Lt) (r2 = 0.907) for males. The mean condition index was 31.29 +/- 0.55% for females and 28.52 +/- 0.19% for males. Both sexes reached the sexual maturity when the males and females overcame the 20.00 mm and 23.5 mm of Lt respectively.     

Growth, size and age at maturity of the agile frog (Rana dalmatina) in an Iberian Peninsula population

The mean age of a population of agile frogs (Rana dalmatina) from the Iberian Peninsula was estimated using mark and recapture and skeletochronology. Life-history parameters, including growth rate, body length, age and size at maturity, sexual dimorphism and longevity, were studied. The regression between age and snout-vent length (SVL) was highly significant in both sexes. Males reached sexual maturity at two years of age, although sometimes they can reach it at only one year of age. The average SVL at maturity was 51.75 mm (standard error (SE) = 0.71; n = 45). Females reached sexual maturity at two years of age with an average SVL of 62.14 mm (SE = 2.20; n = 14). A subset of the female population reached sexual maturity at three years of age. Growth was rapid until sexual maturity was reached. There was an overlap of SVL between different age classes. Growth was continuous, fulfilling the conditions of Von Bertalanffy's model. The growth coefficient (K) was 0.840 in males and 0.625 in females. The maximum SVL was greater in females (73.00 mm) than in males (59.50 mm). Sexual dimorphism was significantly biased towards females in all age classes. The maximum longevity observed was 6 years in females and 8 years in males. Management strategies for agile frogs should take into account factors such as these life-history characteristics.     

The growth of charr, Salvelinus willughbii Günther, in Windermere

The growth of charr ( Salvelinus willughbii Günther ) caught in Windermere from 1941–1952 has been studied. Scales were used for determination of age and back-calculation of length for age. Autumn and spring spawners, males and females, and charr of normal and dwarf growth were treated separately. In fish of normal growth, the spring spawners were significantly smaller than the autumn spawners at ages 1 and 2 years, and significantly larger from age 4 years onwards. There was little difference in growth between males and females within the two spawning populations. Charr of lengths of less than 200 mm at age 4 years were considered to be dwarfs. Mean lengths at capture of male charr were: autumn spawners normal growth 272 mm, dwarf 218 mm; spring spawners normal growth 327 mm, dwarf 194 mm. The oldest recorded age was 8 years.     

Age, growth, reproduction and mortality of the striped seabream, Lithognathus mormyrus (Pisces, Sparidae), off the Canary Islands (Central-east Atlantic)

Striped seabream, Lithognathus mormyrus L. (n=731) caught off the Canary Islands from January 1999 to June 2000 were studied. Fish ranged in size from 113 to 372 mm total length, weighing from 21.1 to 748.2 g total weight. Weight increased allometrically with size (b=2.9071). Fish age was 0–10-years-old. Growth was relatively slow (k=0.88 years⁻¹), with females growing at a slightly faster rate than males. The species displayed protandric hermaphroditism. Male : female ratio was unbalanced in favour of males (1 : 0.85). Males predominated in smaller sizes, females in larger sizes, and intersexual individuals were in intermediate sizes. The reproductive season extended from June to December, with a peak in spawning activity in August–September. Males reached maturity at 207 mm (2 years) and females at 246 mm (3 years). The real value of instantaneous rate of natural mortality was between 0.30 and 0.45 years⁻¹.     

Sex differences in age structure, growth rate and body size of common frogs Rana temporaria in the subarctic

The thermal environment and length of the activity season are important factors in shaping life-history trait variation in ectotherms. Many ectothermic vertebrates living at high latitudes or altitudes tend to be larger and older than their conspecifics living at lower latitudes or altitudes. However, detailed data on age, body size and growth variation—and how they may differ between males and females—are still scarce, especially from extreme high-latitude environments. We studied growth (body length increment), age and size structure of common frogs (Rana temporaria) in subarctic Finland (69°04′N) by applying skeletochronological methods to individually marked adults (n?=?169) captured and recaptured between 1999 and 2003. We found that breeding males were on average younger (mean?=?8.5?years) than females (11.9?years) and that males started reproducing earlier (≥3–4?years of age) than females (>4–5?years). The oldest encountered individual was an 18-year-old female, which to our knowledge is the oldest wild common frog ever reported. Females were on average larger (mean body length?=?76.6?mm) than males (70.7?mm), and this appeared to be mainly due to their older age as compared to males. While body length increased and growth rate decreased with age in both sexes, growth rate declined significantly faster with age in males than in females. The latter finding provides a proximate explanation for the observation that even after accounting for age differences among sexes (females?>?males), females were longer than males.     

Life‐history traits of the leatherjacket Meuschenia scaber,a long‐lived monacanthid

The present study describes the age and growth of the leatherjacket Meuschenia scaber, a common Australasian monacanthid and valued by‐catch of the inshore bottom trawl fishery in New Zealand. Age was determined from the sagittal otoliths of 651 individuals collected between July 2014 and March 2016 in the Hauraki Gulf of New Zealand. Otolith sections revealed alternating opaque and translucent zones and edge‐type analysis demonstrated that these are deposited annually. Meuschenia scaber displayed rapid initial growth, with both males and females reaching maturity in 1–2 years and 50% of both sexes matured at 1·5 years. Maximum age differed substantially between the sexes, at 9·8 years for males and 17·1 years for females. Growth rate was similar between sexes, although males reached greater mass at age than females in the early part of the lifespan. The length–mass relationship differed significantly between the sexes, with males displaying negative allometric growth and females isometric growth. Female condition was highest in July, declined in August with the onset of spawning and showed a slight peak in January and February, immediately following the spawning season. This study substantially extends the maximum longevity recorded for monacanthids, although males had much shorter lifespans and higher mortality, than females.     

Age and growth analysis of the mosshead sculpin Clinocottus globiceps Girard 1857 (Pisces: Cottidae) from Helby Island, British Columbia

The age and growth of the cottid fish Clinocottus globiceps Girard from tidepools at Helby Island, British Columbia, Canada were investigated with the aid of whole saccular otoliths (sagittae); ages were validated by marginal increment analysis. Four hundred and twenty five specimens were examined from 214 females and 211 males. Marginal increment analysis on specimens with one to three opaque zones suggested an annual ring deposition in sagittae during the late autumn and spring months.
The C. globiceps population was composed of individuals from less than 1 year to 5 years of age for fish measuring between 5–120 mm standard length. Growth was faster for younger than for older age groups. Lengths-at-age data were fitted to the Gompertz growth model, and estimates of the model parameters L₀, G and g were 26.7 mm 1.58 and 0.30 for pooled cohorts, respectively. The highest levels of growth occurred during late spring and early summer, when water temperatures were at maximum and food was most abundant. The lowest levels of growth occurred during the autumn and winter months.     

Observations on thermoregulatory ontogeny of mink (Mustela vison)

(1) We measured cooling rate for neonatal mink during a 10min coldroom (3.9 degrees C) exposure and subsequent warming rate during a 20min incubator (37.2 degrees C) exposure, the behaviour of the kits and the changes in their pelage between 1 and 46d of age, in an attempt to monitor the ontogeny of their thermoregulatory capacity. (2) Body weight of the 1d old kits averaged only 12.8+/-2.3g (n=4), but they gained weight rapidly reaching 226.1+/-28.3g (males, n=4) and 207.6+/-16.1g (females, n=4) at 30-31d of age, and 562.3+/-43.2g (males, n=3) and 435.7+/-35.5g (females, n=4) at 45-46d of age. (3) Body cooling rate (C(rate) ( degrees C/min); n=80) was affected by the age (between 1 and 31d), BW, initial rectal temperature (T(r0)), and sex of the kits, in addition to their body posture (P(cold), 1=extended, 2=curled-up) during coldroom exposure. C(rate) ( degrees C/min)=-0.34-0.02age-0.002BW+0.05T(r0)-0.06sex-0.20P(cold) (R(2)=0.75). (4) Body warming rate (W(rate) ( degrees C/min); n=80) was influenced by the age(2) and rectal temperature of the kit after the coldroom exposure (T(r10)). W(rate)( degrees C/min)=1.24+0.0002age(2)-0.04T(r10) (R(2)=0.76). (5) Kit fur fibre length increased from 5.45+/-0.63mm (males, n=2) and 6.20+/-0.20mm (females, n=3) at 22-23d of age to 9.43+/-1.44mm (males, n=4) and 8.70+/-1.89mm (females, n=4) at 30-31d of age, and to 12.93+/-0.47mm (males, n=3) and 11.38+/-0.41mm (females, n=4) at 45-46d of age, the growth averaging about 0.26mm per day. (6) Under normal circumstances newborn mink kits are hypothermic.Their thermoregulation develops only gradually and is dependent on increase in body mass, insulation and behavioural thermoregulation. Their strategy of survival is based on the ability to withstand hypothermia and on the nutrition and warmth provided by the dam.     

Biology of the amphioxus,Branchiostoma belcheri in the Ariake Sea,Japan I. Population structure and growth

We investigated the population structure and growth of the amphioxus Branchiostoma belcheri for four years in the southern Ariake Sea, Japan. We counted 62-66 myotomes and 251-310 dorsal fin-ray chambers, and these results support that this species is an intermediate form of B. belcheri and its subspecies B. belcheri tsingtauense. The ratio of females to males was 1:1.12. Males were more numerous than females among small individuals (< 40 mm body length), but we found no significant differences among large animals (50 mm body length). Spawning occurred from mid June to early July. Groups of newly settled young appeared from January to June of their second year. We observed a large fluctuation between years in the numbers of newly settled young. The estimated size of one-year-old individuals was 19.4 mm in body length; within the next 12 months, they reached 32.1 mm. Three- and four-year-old individuals measured 38.6 mm and 45.8 mm, respectively. Few grew beyond 60 mm; the largest specimen collected was a 64 mm male.     

A skeletochronological analysis of a population of the Anatolia Newt,Neurergus strauchii (Steindachner, 1887) (Caudata: Salamandridae), in Eastern Anatolia,Turkey

This study presents data on age, growth and longevity of a population of Neurergus strauchii in Eastern Anatolia (Bingöl, Turkey) based on skeletochronological data. The phalangeal diaphyseal cross-sections of 54 individuals studied (12♂, 42♀) showed that females are on average older than males: the ages ranged from 6 to 14 years, with an average age of 8.8 years in males and 10.9 years in females. Sexual maturity is reached at an age of 4-5 years in both sexes. The slow growth and the longevity make the species vulnerable.     

Age and size structure of populations of small marbled newts (Triturus marmoratus pygmaeus) from Doñana National Park (SW Spain). A case of dwarfism among dwarfs

The body size of specimens of Triturus marmoratus pygmaeus from Doñana is the smallest recorded for this subspecies. Snout-vent length averages 42.3 mm in males, and 43.9 mm in females. Mean body mass in males is 2.04 g and 2.29 g in females. The age of newts was estimated by means of skeletochronological methods. The maximum longevity recorded was 10 years in females and nine years in males, with one or two years being the age at maturity. As in other newts, body size is not a good predictor of age, since a wide range of body length was found within each age class. Growth in females was substantial in subsequent years, showing an overall positive tendency. However, males showed slight or even negative growth. Newts from Doñana are different from other nearby localities with similar climatic characteristics. This is mainly due to their short juvenile and terrestrial phase.     

Incidence of oligophrenia with fragile X chromosome (FraXq27)

The study of 50 retarded males imbezilitat and idiots, and 100 males with oligophrenia-debilitat in 16-18 years. Severe macroorchism (1.8-4.5 times more, then anthropometric norma for this years) was found at 5 males in first group (10%), and in 8 males in second group (8%). The karyotype was study in 4 males with macroorchism. In 9-15% cells FraX (q27) was found. These data were extrapolated to 600 retarded children preschool and school age. The frequency of oligophrenia with FraX (q27) among all retarded males-8.5 +/- 1.5; retarded heterozygous females among all retarded girls-5.0 +/- 1.3; incidence of oligophrenia with FraX (q27) among all males in population-1:1000; all heterozigous for this gene among all females in population-7:750; retarded heterozygous females in all girls-1:2250 were established.     

Population dynamics and life history of a geographically restricted seahorse, Hippocampus whitei

The aim of this study was to collect data on population dynamics and life history for White's seahorse Hippocampus whitei, a geographically restricted species that is listed as data deficient under the IUCN Red List. Data from H. whitei populations were collected from two regions, Port Stephens (north) and Sydney Harbour (south) in New South Wales, Australia, covering most of the known range of H. whitei, from 2005 to 2010. Over 1000 individuals were tagged using fluorescent elastomer and on subsequent recaptures were re-measured for growth data that were used in a forced Gulland-Holt plot to develop growth parameters for use in a specialized von Bertalanffy growth-function model. Growth parameters for Port Stephens were: females L(∞) = 149·2 mm and K = 2·034 per year and males L(∞) = 147·9 mm and K = 2·520 per year compared with estimates from Sydney Harbour: females L(∞) = 139·8 mm and K = 1·285 per year and males L(∞) = 141·6 mm and K = 1·223 per year. Whilst there was no significant difference in growth between sexes for each region, H. whitei in Port Stephens grew significantly quicker and larger and matured and reproduced at a younger age than those from Sydney Harbour. The life span of H. whitei is at least 5 years in the wild with six individuals recorded reaching this age. Data collected on breeding pairs found that H. whitei displays life-long monogamy with three pairs observed remaining pair bonded over three consecutive breeding years. Baseline population densities were derived for two Port Stephens' sites (0·035 and 0·110 m(-2) ) and for Manly in Sydney Harbour (1·050 m(-2) ). Even though the life-history parameters of H. whitei suggest it may be reasonably resilient, precaution should be taken in its future management as a result of its limited geographical distribution and increasing pressures from anthropogenic sources on its habitats.     

A skeletochronological study of breeding females in a population of Japanese clouded salamanders (Hynobius nebulosus)

The age structure of breeding females of Hynobius nebulosus has not been studied sufficiently. We estimated the ages of 76 individuals from a population in Kyoto by using skeletochronology. The mean age and snout-vent length (SVL) of this population were 4.6 years and 55.7 mm, respectively. It was estimated that the youngest females breed two years post hatching at a mean SVL of 46.5 mm, but a larger number of individuals begins breeding at three years and a mean SVL of 52.2 mm. Because most males also start to breed at three years, there seems to be no gender difference in the timing of sexual maturation. The age of the oldest female was estimated to be 11.8 years. It is possible that the life history of H. nebulosus is characterized by early maturation and arrested growth, and short longevity.