A skeletochronological study of age,growth and longevity in two freshwater turtles,Emys orbicularis and Mauremys rivulata,from Mediterranean Turkey (Reptilia: Testudines)

We estimated growth parameters of Emys orbicularis and Mauremys rivulata in Mediterranean Turkey with the skeletochronological method, using specimens drowned in fyke nets. In adult E. orbicularis, the median age was 8 years in males and 10 years in females. The median age of adult M. rivulata was 10 years for both sexes. Both species reach sexual maturity at an age of 5–7 years. No difference was found in age composition between the sexes.     

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.     

Sexual size dimorphism,growth, and maturity of the fluvial eight-barbel loach in the Kako River,Japan

The maturation and growth pattern of the fluvial eight-barbel loach Lefua sp. (Japanese name: nagare-hotoke-dojo), an endangered species, was investigated using an individual identification-recapture method from 1995 to 1998 in an upper reach of a headwater tributary of the Kako River, Hyogo Prefecture, Japan. Based on observations of the gonads through the abdominal skin, the loach was estimated to breed mostly from May to July. All the males matured by age 1⁺, and all the females matured by age 2⁺. Gamete release in all individuals of both males and females was predicted from recaptured loaches during each breeding season. The standard length of mature females was significantly larger than that of males, showing sexual size dimorphism (SSD). The maximum sizes recorded were 75.4 mm SL for females and 61.2 mm SL for males. Both males and females of immature specimens grew mainly from May to November, including the breeding season, with no significant differences in growth rates between them. After sexual maturity, both males and females grew mainly from July to October (or November), after the breeding season, and the females exhibited higher growth rates than males. Therefore, SSD of the species seems to be attributable to the different growth rates after maturity. The longevity of the loach was estimated to exceed ten years based on individual growth patterns of various sizes during the survey period. It is likely that the loach has an iteroparous life history, breeding every year, and moderate growth rates after maturity.     

Life-history characteristics of a wild population of vervets (Cercopithecus aethiops sabaeus) in Barbados,West Indies

Life history data are presented for a population of vervets, Cercopithecusaethiops sabaeus, in Barbados, West Indies. The data were obtained from two habituated troops and from vervets captured during a large-scale trapping program. Individuals of known age from one troop were weighed periodically, and separate growth curves generated for males and females. The mean weight of captured adult females was 3.3 kg; that of adult males, 5.3 kg. The average age at sexual maturity is estimated at 34 months for females and 60 months for males. Vervets give birth throughout the year, but most infants are born between April and July. The average interbirth interval following a surviving infant is 11.8 months. The mortality of juveniles is heaviest between birth and 2 years of age and decreases thereafter. Males emigrate from their natal troops at sexual maturity and one incident of a juvenile female emigrating is reported.     

Age,growth and mortality of invasive sharpbelly,Hemiculter leucisculus (Basilewski, 1855) in Erhai Lake,China

The sharpbelly Hemiculter leucisculus, an invasive species, has expanded its range throughout much of Asia and into the Middle East. However, little is known of its adaptive changes regarding life history traits such as age, growth and mortality that could possibly explain its success as an invasive species. A detailed study of the invasive sharpbelly was conducted based on 4539 samples collected from July 2009 to June 2011 in Erhai Lake, China. Standard length ranged from 4.3–19.1 cm for females and 4.6–12.3 cm for males. Length–weight relationships for females and males were significantly different and described as W = 0.0076SL^3.2608 and W = 0.0084SL^3.1901, respectively. Otoliths are ideal for age determination because of the single annulus formed each year. Based on marginal increment analysis, the total mean CV for age estimate between two readings was 3.55%. The von Bertalanffy growth curves computed by observed length‐at‐age data were expressed as L_t = 25.6 (1 ? e^{?0.176 (t + 1.347)}) for females and L_t = 16.4 (1 ? e^{?0.354 (t + 0.819)}) for males. According to the age, growth and mortality data, there are three possible reasons for H. leucisculus attaining such dominance within a short time in Erhai Lake. First, because of the simple age structure of this species: 97.58% of males were 1–2 years old with a maximum age of only 3 years; 93.14% of females were 1–3 years old, with a maximum age of 6 years. Second, females grew larger than males at any age. Third, instantaneous mortality rates were much higher for males (4.22 year^?1) than for females (1.17 year^?1).     

Life expectancy,maximum longevity and lifetime reproductive success in female Thornicroft's giraffe in Zambia

Gestation and longevity scale with body mass across taxa, yet within size dimorphic taxa, males tend to have reduced lifespans compared with females. Testing life history models, and accounting for sex differences in longevity, requires obtaining accurate longitudinal data from wild populations. We provide the first report describing key life history parameters from a long‐term study of giraffes in Africa. We followed a population of Thornicroft's giraffe (Giraffa camelopardalis thornicrofti) in Zambia for over 40 years. Maximum longevity among females was approximately 28 years, with lifespan accounting for 81% of the variance in lifetime reproductive success. Average adult female life expectancy was no different than average adult male life expectancy. However, the breeding lifespan of males was about half that of females, while maximum lifespan of males was 75% that of females. Our findings support the suggestion that sex differences in maximum lifespan arise from stronger selection for lengthy lives in females than in males. Among females, longer lives are associated with greater reproductive output.     

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.     

Growth in captivity and aspects of reproductive biology of the Antarctic fish parasite Aega antarctica (Crustacea,Isopoda)

Summary Specimens of the fish parasite Aega antarctica caught in the Weddell Sea and off the South Shetlands and South Orkneys were kept in aquaria for more than 2 years. These isopods were fed with plaice (Pleuronectes platessa) from the North Sea. Growth in captivity was very slow. For the first growth phase before reaching sexual maturity of females the value K = 0.12 was calculated for the Bertalanffy growth constant. Mature males are markedly smaller than breeding females (average lengths: 16.0 and 22.5 mm). An age of more than 5 years was calculated for an average-sized male, females spawn at an age of more than 10 years. No evidence for protandric hermaphroditism could be found.     

Reproductive cycle,sexual maturity and longevity of Odontophrynus americanus (Anura: Odontophrynidae) in South Brazil

Studies on the reproductive biology and age of amphibians provide primary information about the life history and population demographic parameters of species. Here, we describe the reproductive cycle, size–fecundity relationships, reproductive effort, sexual dimorphism and sexual maturity of Odontophrynus americanus, the flood frog, from South Brazil. A total of 96 individuals were analysed. The reproductive cycles of males and females were described through morphoanatomical analysis of testis and ovary. Age at onset of sexual maturity and estimated longevity were determined by skeletochronology. Individuals of O. americanus presented a potentially continuous reproductive cycle with a peak of reproductive activity in the warmer months. Females presented a higher reproductive investment than males. Sexual maturity was reached at around one year of age for both sexes while longevity differed between the sexes, with females living up to six years and males up to ten years. No evidence of sexual size dimorphism was found. This study is among the few that have assessed age at sexual maturity and longevity in a Neotropical anuran. Basic aspects of life history are of paramount importance because they allow comparisons and test of hypotheses to be made, which can help to build generalizations about the evolutionary meaning of ecological strategies.     

Age,growth, and age at sexual maturity of the commercially landed skate species,Dipturus chinensis (Basilewsky, 1855), in the northern East China Sea

Age, growth, and age at sexual maturity of the polkadot skate Dipturus chinensis, in the northern East China Sea were determined for a total of 614 specimens collected from April 2009 to December 2014. Vertebral centrum analysis was used to calculate the age of the skates. Annual band deposition was determined by marginal increment analysis. The von Bertalanffy growth model was fitted to the observed length‐at‐age data for each sex (males, L_∞ = 76.8, k = 0.109, t₀ = ?1.28; females, L_∞ = 83.1, k = 0.103, t₀ = ?1.20). Growth patterns of females and males were similar until the age of 6; thereafter, females grew larger than males. Maximum age recorded was 13 years for males and 15 years for females. Age at 50% sexual maturity was 8.22 years for males and 9.39 years for females. These results indicate that D. chinensis is slow growing, relatively long‐lived, and late maturing, and therefore vulnerable to exploitation.     

Growth and derived life-history characteristics of the Brazilian electric ray Narcine brasiliensis

The majority of batoids are listed as Threatened (20.4%) or Data Deficient (41%) by the IUCN Red List. A key challenge to assessing Data-Deficient species is obtaining estimates of key life-history characteristics. Here, a Bayesian approach was used to estimate derived life-history characteristics from a growth model applied to the Data-Deficient Brazilian electric ray Narcine brasiliensis. The age of 170 specimens (107 females, 63 males) was estimated from vertebral centra, and total length, disc width, total weight and birth size were used in a joint estimation of sex-specific length-weight models and two-dimensional von Bertalanffy growth models. Estimates of age at length zero, age at maturity, longevity and mortality at age were derived simultaneously. The Bayesian joint modelling approach was robust to small sample sizes by adding a likelihood to constrain L₀ and sharing parameters, such as Brody growth coefficient between length measurements. The median growth parameter estimates were a shared L₀ = 38.8 mm, female L_∞ = 515 mm, 𝑘 = 0.125 and male L_∞ = 387 mm, 𝑘 = 0.194. Age at maturity was estimated to be 7.40–7.49 years for females and 4.45–4.47 years for males, whereas longevity was 22.5–22.6 years for females and 14.2 years for males depending on length measurement. Age-1 natural mortality was estimated to be 0.199–0.207 for females and 0.211–0.213 for males. The derived life-history characteristics indicate N. brasiliensis is earlier maturing, but slower growing relative to other Torpediniformes. These characteristics along with the species’ endemism to southern Brazil and high by-catch rates indicate that one of the IUCN Red List threatened categories may be more appropriate for the currently Data-Deficient status. The Bayesian approach used for N. brasiliensis can prove useful for utilizing limited age-growth data in other Data-Deficient batoid species to inform necessary life characteristics for conservation and management.     

AGE,GROWTH, AND REPRODUCTIVE PATTERNS OF DALL'S PORPOISE (PHOCOENOIDES DALLI) IN THE CENTRAL NORTH PACIFIC OCEAN

Life history parameters were estimated for Dall's porpoise, Phocoenoides dalli, from biological specimens collected in the western Aleutian Islands, during 1981–1987. Of 2,033 males and 3,566 females examined, reproductive data were available for 1,941 males and 1,906 females; ages were determined for 813 males and 1,297 females. Female sexual maturity was based on the presence of one or more corpus on either ovary; 845 were sexually immature and 1,061 were sexually mature. Two estimates of female average age at sexual maturity (ASM) were 3.8 and 4.4 yr; average length at sexual maturity (LSM) was 172 cm. Males were considered sexually mature when evidence of spermatogenesis was detected; 1,136 were sexually immature and 805 were sexually mature. Two estimates of male ASM were 4.5 and 5.0 yr; LSM was 179.7 cm. Physical maturity was assessed for 246 males and 446 females by examining the degree of fusion in thoracic vertebral epiphyses. For both sexes, the average age at physical maturity was 7.2 yr. Average length at physical maturity was 202.6 cm for males and 192.7 cm for females. Average lengths of physically mature males (x?= 198.1 cm, SE = 0.8566) and females (x?= 189.7 cm, SE = 0.4002) were significantly different(P < 0.0001). Early postnatal growth was rapid in both sexes. A secondary growth spurt in both mass and length was characteristic for both sexes; the increase in length preceded the mass increase by 1–2 yr. Average length at birth (LOB) was approximately 100 cm; birth mass averaged 11.3 kg (SE = 0.0772). By the time the umbilicus had healed (<2 mo), the average length and mass had increased to 114.1 cm and 23.8 kg, respectively. Gestation period based on projections using LOB was 12 mo, but this was considered an overestimate. Calving was modal, centered in early July; an annual reproductive interval was indicated. Among the sexually mature females, 120 were pregnant, 55 were pregnant and lactating, 321 were pregnant with colostrum, and 33 were “resting.” By 3 July (95% CI =x? 1 d), 50% of births had occurred, during each of the seven years sampled. The ovulation rate was estimated at 0.914 ovulations per average reproductive year. Enlarged follicles and recent ovulations were observed in postpartum females in late July.     

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.     

Longevity,Demography and Sex-Specific Growth of the Pampa de Achala Toad,Bufo achalensis CEI, 1972

The demography and life history parameters of the neotropical Bufo achalensis, an endemic toad of the Pampa de Achala, Sierras Grandes de Cordoba, Argentina, were studied in 13 activity periods between 1970/71 and 1998/99. We used phalange bones for skeletochronological age estimation and to assess annual growth rates in 243 individuals. Maximum longevity was 11 years, and sexual maturity was attained at an age of 2–4 years. Reproductive females were on average 4–8 mm smaller than males of the same age. There is no indication that the population of B. achalensis is declining as observed in several neotropical amphibian species.     

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.     

Age-based life history of humpback red snapper,Lutjanus gibbus,in New Caledonia

This paper examines the life history of humpback red snapper Lutjanus gibbus, an important fishery species for coastal communities across the Indo-Pacific, in southern New Caledonia, where the species is lightly exploited. A total of 243 L. gibbus were sampled between January 2013 and December 2016 from occasional harvests of commercial fishers. Examination of sectioned otoliths revealed that opaque increment formation occurred annually between November and March, coinciding with the species' spawning season. Estimates of maximum age were similar between sexes, with observed ages of 38 and 36 years for females and males, respectively, extending the reported longevity of this species by at least 11 years. Growth differed significantly between sexes, with males reaching greater length at age and greater asymptotic length than females (38.88 v. 31.46 cm fork length (L_F). Total mortality for all samples was estimated as 0.13 and was slightly higher for males (0.16) than females (0.11). Estimates of natural and fishing mortality were low and slightly higher for males than females. Male L. gibbus were found to mature at slightly greater lengths and younger ages than females, with the length and age at which 50% of individuals attained maturity estimated to be 25.8 cm L_F and 3.9 years of age for females and 26.8 cm L_F and 3.4 years of age for males. The results provide key baseline information from which to assess the effect of fishing on the species for populations in New Caledonia and adjacent locations and, when viewed with those of other studies, highlight the importance of understanding spatial patterns in demography of harvested fish species across gradients of exploitation and environmental influences.     

Effects of delayed mating and male mating history on longevity and reproductive performance of the rice stem borer, Chilo suppressalis (Walker) (Lep., Pyralidae)

Abstract:  The mating potential, effects of delayed mating and male mating history on longevity and reproductive performance of female rice stem borer (RSB), Chilo suppressalis , were investigated under laboratory conditions. Given the opportunity, RSB males copulated an average of 2.7 times, while females generally mated only once. Females were more severely affected by mating delay than males in terms of female longevity and reproductive performance. With increasing age at mating, females' longevity increased, while oviposition period, fecundity and egg fertility decreased. Mean fecundity and egg fertility of females mated 1 and 7 days after emergence were 251.3% and 99.2%, and 96.2% and 75.5% respectively. Both were reduced significantly when female mating was delayed beyond 4 days after emergence. However, irrespective of the first mating age and different mating history of the males, the results indicated that both did not result in a significant difference in the quality of their contributions to female longevity and reproductive performance. The results obtained in this study are discussed in relation to the potential effect on pheromone control of RSB.     

Estimation of age structure by skeletochronology of a population of Hynobius nebulosus in a breeding season (Amphibia,Urodela)

Using skeletochronology, we determined the age structure of adult Hynobius nebulosus from Kyoto in the breeding season of 1998. From previously marked individuals, the lines of arrested growth proved to be formed once per year, indicating the number of winters each salamander experienced. The age at first reproduction was estimated to be 2.8-2.9 yrs of age in males and 3.8-3.9 yrs in females. The oldest males and females were 9.8-9.9 and 5.8-5.9 yrs of age, respectively, and, therefore the longevity in this species was estimated to be more than 9 yrs for males and 5 yrs for females. The growth curve of male's body size estimated indicated that the growth rate much decreases after males attained sexual maturity. Because body sizes of adults greatly vary even within an age class, it is dangerous to estimate individual age from the size frequency data at least in adults. We discussed age properties in Hynobius by comparing lentic and lotic breeders.     

Age, growth, maturity, and mortality of the Alaska skate, Bathyraja parmifera, in the eastern Bering Sea

The Alaska skate, Bathyraja parmifera, is the most abundant species of skate on the eastern Bering Sea shelf, accounting for over 90% of total skate biomass. However, little is known regarding the life history of this species despite its common occurrence as bycatch in several Bering Sea fisheries. This is the first study to focus on the age and growth of B. parmifera. From 2003 to 2005, more than one thousand specimens were collected by fisheries observers and on scientific groundfish surveys. Annual banding patterns in more than 500 thin sections of vertebral centra were examined for age determination. Caudal thorns were tested as a potentially non-lethal ageing structure. Annual band pair deposition was verified through edge and marginal increment analyses. A three-parameter von Bertalanffy growth function and a Gompertz growth function were fit to observed length-at-age data. Both models provided significant fits, although the Gompertz function best described the overall pattern of growth in both males and females, based upon statistical criteria and parameter estimates. Age and size at 50% maturity were 9 years and 92 cm TL for males and 10 years and 93 cm TL for females. The maximum observed ages for males and females were 15 years and 17 years, respectively. Estimates of natural mortality (M) ranged from 0.14 to 0.28, and were based on published relationships between M and longevity, age at maturity, and the von Bertalanffy growth coefficient. Due to these life history characteristics and a lack of long-term species-specific stock data, a conservative management approach would be appropriate for B. parmifera.     

Age,growth and reproduction in creole perch (Percichthys trucha) in the Negro River,Argentinean Patagonia

Age, growth and reproductive characteristics of creole perch, Percichthys trucha, were investigated in the Negro River, southern Argentina from samples collected seasonally, December 1994–December 1995. Age was estimated via scale and whole otolith reading methods. Total length (n = 413) ranged from 103 to 432 mm, and weight from 12 to 1042 g. Significant differences between the length‐weight relationships of males and females were detected (P < 0.05). Isometric growth was observed in juveniles and males, whereas total population and females exhibited positive allometric growth. The marking pattern in scales and otoliths followed an annual rhythm, with the formation of only one annulus in scales and only one hyaline band in otoliths during autumn‐winter. The oldest males were 5 years old whereas maximum age in females was 12 years from scales and 15 years from otoliths. Because scales were found to underestimate age in individuals older than 4 years, otoliths were considered to be the best structures for creole perch age determination. Gompertz growth parameters based on otolith data were L∞: 428.0 mm, k = 0.46 and t₀ = 0.43 for total population (r = 0.90), L∞: 410.7 mm, k = 0.42 and t₀ = 0.46 for males (r = 0.91), and L∞: 434.1 mm, and k = 0.49 and t₀ = 0.43 for females (r = 0.91). Lengths at first maturity (TL₅₀) were 260 and 241 mm in males and females, respectively, both of which corresponded to ages between 1 and 2 years. Macroscopic gonad inspection and the high percentage of juveniles captured during summer indicated that spawning begins at the end of spring.