Age and growth

Growth rates and longevities were estimated for five major fishery species of parrotfishes (“uhu”) at Oahu, Hawai’i. All species grew rapidly with von Bertalanffy growth formula k values ≥0.4·year−1. Longevities were found to range broadly among the three small species, 4 years in Calotomus carolinus and 6 and 11 years in Scarus psittacus and Chlorurus spilurus, and to 15–20 years in Scarus rubroviolaceus and Chlorurus perspicillatus for the two large species. Age reading and growth curves for the latter two large species were validated using bomb radiocarbon dating. Median ages at sexual maturity as females (AM50) and at sex change (from female to terminal phase male, AΔ50) were estimated using logistic models. Sexual maturation occurred at 1–2 years for the small species and at 3–3.5 years in the large species. AΔ50 estimates ranged from 2 to 4 years in the small species and were about 5 and 7 years in S. rubroviolaceus and C. perspicillatus, respectively. Estimated milestones poo...

The aim of this study was to evaluate the changes in the ghrelin, leptin, and fat levels in the foremilk and hindmilk and the possible relationship between these levels with the age and growth of term healthy infants. Sixty-two babies were subdivided (according to their nutrition) into breastfed (BF), formula-fed (FF), and BF plus FF (BF + FF) groups. The total and active ghrelin and tryglyceride levels and the total cholesterol levels in the foremilk and hindmilk were studied at the first and second visits (mean of the second and fifth months, respectively). At both visits, the total and active ghrelin and the total cholesterol levels were lower in the hindmilk than in the foremilk. However, the triglyceride levels were higher in the hindmilk than in the foremilk (p < 0.001). The leptin levels were also higher in the hindmilk, but this difference was not statistically significant. At the second visit, the mean total foremilk ghrelin (p < 0.01), leptin (p < 0.05), tryglyceride (p < 0.001), and cholesterol (p < 0.01) levels in the BF group were decreased compared with the levels at the first visit, whereas the active ghrelin levels increased (p < 0.001). At the second visit, we observed a 3.5% increase in the body mass index in BF infants, a 14.6% increase in FF infants, and an 11.8% increase in BF + FF infants (p < 0.01). The foremilk leptin levels were lower in the BF + FF group than in the BF group at both visits. In conclusion, at the first and second visits, the decreased ghrelin and increased tryglyceride and leptin levels in the hindmilk might be associated with the important role of self-control when feeding BF infants. The stable content of formulas might be associated with a lack of self-control during feeding and increased nutrition. Changing the breast milk ghrelin, leptin, and fat levels between the foremilk and hindmilk and between the first and second visits might explain the differences in the weight gain patterns of BF and FF infants.

Validated age and growth estimates are important for constructing age-structured population dynamic models of chondrichthyan fishes, especially those which are exploited. We review age and growth studies of chondrichthyan fishes, using 28 recent studies to identify areas where improvements can be made in describing the characteristics of ageing structures (both traditional and novel) utilized to estimate ages of sharks, rays, and chimaeras. The topics identified that need consistency include the: (1) terminology used to describe growth features; (2) methods used to both verify and validate age estimates from chondrichthyan calcified structures, especially edge and marginal increment analyses; and (3) the functions used to produce and describe growth parameters, stressing the incorporation of size at birth (L 0 ) and multiple functions to characterize growth characteristics, age at maturity and longevity.

Age and growth of the brown meagre Sciaena umbra (Sciaenidae) collected in the north-western Adriatic Sea was studied by means of transverse otolith sections. The maximum age estimated was 19 and 16 years for males and females, respectively.

The Atlantic chub mackerel, Scomber colias Gmelin, 1789, is one of the main fisheries resources of Madeira Island. It is caught by a small and coastal purse-seine fleet that traditionally operates around the island. In 2002 and 2003, monthly samples of Atlantic chub mackerel were collected from the landings of this commercial fishing fleet. A total of 2212 sagitta otoliths were extracted for age readings from 1068 males (17.4-41.7cm total Length, TL), 1066 females (18.0-41.2 cm TL) and 78 undetermined (13.0-26.8 cm TL). A single reader aged the fishes using surface-read whole otoliths aiming to build annual age-length keys. Age readings precision and consistency were assessed by using the average percentage error (APE=1.19), precision index (PI=1.34) and coefficient of variation (CV=2.33). Ages were validated up to 4 years using otoliths’ edge and relative marginal increment analyses. Length von Bertalanffy growth parameters were estimated by using non-linear methods (L∞=56.48 cm TL...

White hake (Urophycis tenuis) is a locally important commercial fish in the Gulf of St. Lawrence. The mean landings during the past 30 years have been about 6500 tonnes, the third most important demersal species.
Despite this, little biological work was conducted on this species before the early 1980's. Age determination is a key element in the analytical assessment process and this report attempts to define the age determination techniques, interpretation criteria, and growth estimated for white hake in the southern Gulf.
White hake are often landed in a semi-processed state, head-off and gutted. A variety of conversion factors were investigated to account for this difficulty. The most satisfactory conversion was found to be total fish
length to first dorsal fin length. An alternate conversion using otolith weight was also developed to estimate total length, and allow age determination, from a sample of heads only.
A comparison of growth estimated from otoliths and vertebrae indicates both these hard parts exhibit the same pattern of ring formation. Marginal increment analysis indicates the slow growth zone ring is laid down
in spring and early summer. Modal analysis of research survey length frequency data indicate year classes of fish at the same general size as determined from counting the rings on the otoliths. Growth of white hake is
sexually dimorphic and is near linear for the ages most commonly found in the commercial fishery. From von Bertalanffy growth estimates, L GO for males is about 86 cm and for females is about 136 cm. These values
appear reasonable compared to the largest fish caught in our annual resource surveys.

Age and growth of Nile tilapia (Oreochromis niloticus) were determined using 1 039 specimens collected in a tropical shallow lake of Mexico, from January to December 1993. Standard length of females ranged from 9.0 to 16.5 cm and males from 8.9 to 14.8 cm. The standard length-weight relationships for all individuals was BW=0.1207 SL 2.469 . The age data, derived from opercular bone readings, were used to estimate the growth parameters of the von Bertalanffy equation: L ∞ =17.88 cm, K=0.3409, t o =-1.543, and W ∞ =149.21 g. The oldest male and female were 2.5 years old. The sex ratio (female:male) was of 1:1 (χ²=0.02, p>0.05). Rev. Biol. Trop. 56 (2): 000-000. Epub 2008 June 30.

RandallÕs threadfin bream, Nemipterus randalli, first recorded in Iskenderun Bay in Turkey in 2008, seems to have increased in the region. The species, widespread in the western Indian Ocean and with a rapid expansion, appears to have migrated to the bay via the Red Sea. Although its presence in the region has been published, there has been little or no information as to age and growth parameters of this Lessepsian migrant in its new habitat. The present study aims to determine the basic age and growth parameters of the species colonized in the region. A total of 379 collected individuals were studied from November 2007 to October 2008. Total specimen lengths ranged from 4.80 to 21.50 cm, and weights from 1.10 to 138.36 g. Maximum age was 3 years for both sexes. The length-weight relationship was described as W = 0.0011 · L 3.061 (r 2 = 0.982). The von Bertalanffy growth parameters were: L ¥ = 34.96 cm; K = 0.214 year )1 ; t 0 = )1.244 year for the entire population. These data were compared with results from studies made in other geographic areas.

Age estimates were made on otoliths of 21 juvenile swordfish, Xiphias gludius Lirmaeus, captured in the Mediterranean Sea. Increments were observed in swordfish sagittae sectioned in a transverse plane and viewed with light and scanning electron microscopy. Increment counts, presumed to be daily, were made for age estimation. Estimated ages ranged from 87 to 147 days of fish ranging in size from 51 to 74 cm lower jaw fork length (LJFL). A growth rate of 2.3 cm.day-' for the range of size of the fish was estimated. Spawning dates were estimated to occur from June 27 to August 25, which is consistent with reported times of gonad maturation and occurrence of swordfish larvae in the plankton.

... Research 33 (1997) 123129 Age and growth of the sparids Diplodus vulgaris, D. sargus and D. annularis in adult populations and the differences in their juvenile growth patterns in the northwestern Mediterranean Sea Ana Gordoa &amp;#x27;&amp;#x27;, Balbina Moli Centra de Estudios Avanwdos ...

Sharp declines in catches prompted a detailed study of the commercially and culturally important 'terubok' Tenualosa toli, which lives in the fast-flowing, turbid estuaries and adjacent shallow coastal waters of Sarawak. Its reproduction, diet, age and growth were investigated. An absence of small females and large males, together with histological data showing transitional gonads, suggest that 7: toli is a protandrous hermaphrodite. Ageing based on otoliths indicates that individuals may not live more than about two years. Male fish spawn towards the end of their first year, change sex (transitional gonads were recorded in fish from 14 to 31 cm SL) and spawn as females in their second year. Spawning takes place in the middle reaches of estuaries and females deposit all their eggs at once. Fecundity is linearly related to fish length but shows significant seasonal and site variations. Hermaphroditism is discussed in relation to possible environmental and isolating mechanisms. i? toli is a zooplanktivore eating mainly calanoid copepods. Laser-ablation inductively-coupled plasma mass spectroscopy of trace elements across otoliths revealed that the species does not move into full seawater or freshwater, but completes its life cycle in estuarine and adjacent coastal waters. Therefore 7: toli populations in each estuary and adjacent coastal waters may be relatively isolated from one another, and hence particularly susceptible to overfishing.

Age and growth of the yellowbelly threadfin bream Nemipterus bathybius in Kagoshima Bay, southern Japan were examined using sectioned otoliths of 1359 fishes collected from April 1998 to November 2000. Monthly changes in marginal growth increments indicated that ring marks (outer edge of opaque zone) were formed once a year between May and August. Assuming a birth date of 1 July from the monthly change of gonadosomatic index, ages ware assigned to every individual according to the number of ring marks. Length-at-age and weight-at-age data were best fitted to the von Bertalanffy among the three growth models. Equations obtained were FL t = 274.7(1 -exp( -0.341( t + 0.762))) for males and FL t = 231.0(1 -exp( -0.161( t + 4.405))) for females, where t is age (year) and FL t is the fork length (mm) at age t , and they were significantly different (i.e. males grew faster than females). Maximum age observed was approximately 8 years for males and approximately 10 years for females.

The white-spotted rabbitfish Siganus canaliculatus feeds mainly on seaweeds and seagrass during most part of the year in the Omani waters. The presence of benthic invertebrates like polychaetes, small shrimps and bivalves in large sized fish appears to be accidental inclusions. Majority of mature fish occurred with empty stomach or with little food during spawning season. The monthly hepato-somatic index ranged from 1.1 to 1.73 in males and 1.06 to 1.8 in females and the values were generally higher prior to spawning months. The length-weight relationships of males and females differed significantly (p < 0.05) and can be expressed as log W = -4.0395 + 2.6736 log L for males and log W = -4.3544 + 2.8048 log L for females.

Age and growth of Labeo bata (Ham .) was studied by the analysis of annuli found on the scale and by length-frequency distribution. The fish attained lengths of 131,194, 236, 277, 314, 341 and 364 mm at the end of the 1st, 2nd, 3rd, 4th, 5th, 6th and 7th years of life respectively . The increase in length of scale bears a constant relationship with the increase in length of fish, and regression analysis yielded a straight line between scale and body length . Calculated values could be expressed as :

A total of 146 otoliths were extracted for age readings from 68 females (23.2-90.1 cm TL), 76 males (22.0-81.3 cm TL) and 2 undetermined (30.3-38.0 cm TL), between April 2004 and December 2007. The maximum age obtained from whole otoliths was 11 years. Differences in the growth rhythms were observed between the sexes (females: L∞=134.4, K=0.092 and t0=−0.406; males: L∞=135.9, K=0.078 and t0=−0.894; and all fish were: L∞=149.8, K=0.078 and t0=−0.784). Pink dentex attain 50% of their maximum theoretical length during their fourth year of life. The weight-length relationship (W = q Lfb) were determined separately for each sex and for all fish: for females q=0.01094 and b=3.033, for males q=0.10002 and b=3.047 and for all, q=0.01027 and b=3.046. According to the F-test, there were no significant differences between the weight-length relations obtained for females and males (F-test, F=2.2526, p=0.06646).

Some of the most basic questions of sea turtle life history are also the most elusive. Many uncertainties surround lifespan, growth rates, maturity and spatial structure, yet these are critical factors in assessing population status. Here we examine the keratinized hard tissues of the hawksbill (Eretmochelys imbricata) car-apace and use bomb radiocarbon dating to estimate growth and maturity. Scutes have an established dietary record, yet the large keratin deposits of hawksbills evoke a reliable chronology. We sectioned, polished and imaged posterior marginal scutes from 36 individual hawksbills representing all life stages, several Pacific populations and spanning eight decades. We counted the apparent growth lines, microsampled along growth contours and calibrated D 14 C values to reference coral series. We fit von Bertalanffy growth function (VBGF) models to the results, producing a range of age estimates for each turtle. We find Hawaii hawksbills deposit eight growth lines annually (range 5–14), with model ensembles producing a somatic growth parameter (k) of 0.13 (range 0.1–0.2) and first breeding at 29 years (range 23–36). Recent bomb radio-carbon values also suggest declining trophic status. Together, our results may reflect long-term changes in the benthic community structure of Hawaii reefs, and possibly shed light on the critical population status for Hawaii hawksbills.

The population dynamics parameters of Diplodus vulgaris (Sparidae) from the south and south-west coast of Portugal were studied. 1086 fishes with total lengths ranging from 3.3 to 37.9 cm were obtained from previous gear selectivity studies supplemented by market sampling and beach seining for juveniles (1992)(1993)(1994)(1995)(1996)(1997)(1998)(1999)(2000). The spawning season extended from September to April and total lengths at 50% maturity were 17.27 cm for males and 17.65 cm for females. These estimated sizes were greater than the minimum legal landing size (MLS = 15 cm) and smaller than length at first capture (Lc 50 = 21.68 cm) for the longline fishery. The parameters of the von Bertalanffy growth equation were: L ∞ = 27.73 cm, K = 0.40 per year, t 0 = −0.34 year. The instantaneous rates of total mortality (Z) and natural mortality (M) were 0.63 and 0.45 per year, respectively. Rates of fishing mortality F and exploitation E were 0.18 and 0.28 per year, respectively. Estimated parameters and the relative yield-per-recruit analysis showed that this species is not over exploited by longlines.

Age and growth of Labeo bata (Ham .) was studied by the analysis of annuli found on the scale and by length-frequency distribution. The fish attained lengths of 131,194, 236, 277, 314, 341 and 364 mm at the end of the 1st, 2nd, 3rd, 4th, 5th, 6th and 7th years of life respectively . The increase in length of scale bears a constant relationship with the increase in length of fish, and regression analysis yielded a straight line between scale and body length . Calculated values could be expressed as :

Giant trevally (Caranx ignobilis) are an iconic reef fish of the Indo-Pacific, and yet knowledge of their life history is incomplete. The species is common in tropical and subtropical waters ranging from the far western Indian Ocean off South Africa to the central Pacific Ocean, where the species attains its greatest recorded size in Hawaii. Despite their broad range, importance as a top predator and attraction among anglers, the age and longevity of giant trevally remain largely undescribed and there are concerns that giant trevally are being fished down in the Hawaiian Islands. The most comprehensive age and growth study was performed in the Hawaiian Islands, but the work was limited to early growth observations. Although a study of daily increments was limited to fish less than maximum size, a model used to describe the growth characteristics was extrapolated to estimate that maximum age may exceed 20 years. In this study, otoliths of giant trevally from the Hawaiian Islands were investigated for annual growth zones, and the validity of the age estimates was tested and validated with bomb 14C dating. Revised growth parameters indicate giant trevally grow rapidly in the Hawaiian Islands and can attain an age of 25 years.

The relationship between the size, age and growth rate of firms is examined for a large sample of micro and small firms in Sweden. These firms have between 1–100 employees and operate in a geographically concentrated area. Micro and small firms are dominant in the industrial structure and thus their growth patterns are crucial to the economic growth of the region. The period of study is of particular interest because it allows us to evaluate the effects of various regional development policy programs on the growth and formation of firms. The data is an unbalanced panel covering the period 1993–1998. We allow for the exit and entry of firms. The growth rate is defined in terms of the number of employees, sales and assets. In the estimation of the growth rate we control for various factors characterizing the sample firms, their capital structure, performance, human capital, and local labor market conditions. Our results show that the relationship between the growth, size and age of firms is very sensitive with respect to the method of estimation, functional form and definition of growth and size.

Biology and population dynamics of the suspension-feeding wedge clam Donax trunculus (Linnaeus, 1758) were studied for 13 months (November 1994-April 1996 along the Italian Southern Adriatic coast near the Lagoon of Lesina. Specimens were found at depths between 0 and 2 m, mainly in fine grain bottoms. The spatial coastal distribution showed an intraspecific segregation between young and adult wedge clams. A unimodal recruitment (length >4 mm) occurred in winter (December-February). Length frequency distributions were used to determine age and growth rate. Three year classes were regularly observed and their growth pattern defined. The population showed a maximum length of 37 mm and a longevity of 4 years. Analysis of seasonal variations in the reproductive cycle showed that gametogenesis occurred in spring in females. After the spawning season (March-July) females of D. trunculus remained in a resting stage from August to January.

A total of 216 dorsal fin spines from western Mediterranean bullet tuna were analyzed from 2003 to 2006 for ageing and growth studies. The length of the aged individuals ranged from 31 to 44 cm for the males and from 31 to 46 cm for the females. Fish ages ranged 2 to 5 years old and the mean lengths by age were calculated for males and females. Growth parameter estimates were calculated from 206 cut spine sections which provided readable growth annuli by sex. The standard von Bertalanffy growth function was used to fit length at-age data. The growth parameters based on standard von Bertalanffy growth function are the following: for males, L ∞ (asymptotic length)=43.751 cm, k (growth coefficient)=0.865, t 0 (age at zero length)=-0568; for females, L ∞ =45.545 cm, k=0.461, t 0 =-0.821; for both sexes, L ∞ =44.041 cm, k=0.700 , t 0 =-0.139. The relationships between FL and dorsal fin spine diameter were calculated for both sexes. Age-length keys were provided for catch at age calculation application.

The age and growth of the marbled spinefoot, Siganus rivulatus Forsska Êl, 1775, were determined based on specimens collected from Antalya Bay (eastern Mediterranean), during the period from October 1996 to August 1998. Total length±weight relationship was estimated as W 0:0064L 3:221 for females, W 0:0079L 3:135 for males. Growth parameters of the von Bertalanffy equation were computed for females and males as: L I 22:55 cm; W I 146:8 g; k 0:267 yr À1 ; t 0 À0:47 and L I 21:06 cm; W I 112:1 g; k 0:343 yr À1 ; t 0 À0:54, respectively. Age was determined by posterior body scale readings. Maximum observed age was 8 years, suggesting that the species is long-lived. #

Marginal increment ratio (MIR) analyses were conducted as part of age and growth studies on three coastal/semi-oceanic species, the smalltail shark, Carcharhinus porosus, dagger-nose shark, Isogomphodon oxyrhynchus and the night shark C. signatus, and two ubiquitous oceanic species, blue shark, Prionace glauca, and whitetip shark, C. longimanus, collected in equatorial areas off Brazil with the aim of establishing the interspecific temporal nature of vertebral band formation. Monthly variations in marginal bands were analyzed using mean MIR on the entire sample as the standard method for all species. Reasons for the inconclusive results regarding these species are critically appraised with respect to three main sources of bias that are associated with marginal increment analysis (MIA). Bias due to insufficient sample sizes may have hampered the analysis for I. oxyrhynchus and C. longimanus due to movements from shallow waters to seamounts for the former species and to extensive migrations for the latter. Bias due to data collection over too long a period is thought to have influenced monthly mean MIR for C. porosus and P. glauca. For the latter, individuals from different age groups lay down rings at different times, making band deposition inconsistent between individuals. Finally, bias due to births occurring over too long a period was the prevalent cause for confounding MIR values among I. oxyrhynchus and C. signatus species, whose birth period lasts several months and leads to different ages within the same cohort. Other approaches used for MIA in C. signatus and P. glauca led to distinct times of band formation by age-groups when compared to MIR applied on the entire sample. For the daggernose shark, delays in events related to the reproductive cycle from one year to the next were also found to confound MIR. Requirements for the use of MIR implying a band width that displays a sinusoidal cycle when temporally plotted (month or season) were not fulfilled for any of these species. The method has been of little utility for detecting the periodicity of band deposition among sharks from the tropics. This emphasizes the need for supplying information on the temporal periodicity of pair deposition based on other methods.

Montane Norway spruce forests of Central Europe have a very long tradition of use for timber production; however, recently there has been increasing concern for their role in maintaining biological diversity. This concern, coupled with recent severe windstorms that led to wide-spread bark beetle outbreaks, has brought the management of montane spruce forests to the forefront of public policy discussions in Central Europe. In order to shed light on the natural development and current structure of mature montane spruce forests, we established four 0.25 ha research plots in a semi-natural montane spruce forest in thě Sumava Mountains (The Bohemian Forest), Czech Republic. We mapped all trees, extracted increment cores for age and growth-pattern analyses, and inventoried all current tree regeneration, including the substrates on which it was found. Stands were characterized by uni-modal tree diameter distributions and high basal areas (56.6 m 2 ha −1 on average), indicating a natural transition from the stem exclusion phase towards the understory reinitiation phase. The stands showed largely single-cohort recruitment age structures, however, with recruitment spanning seven decades. Our analyses suggest that this cohort existed as advance regeneration prior to major disturbances in the late 1800s, which included post-bark beetle salvage logging. Spatial pattern analyses of living and dead stems combined, showed an increase in uniformity of living trees, pointing to the role of natural density-dependent mortality. However, past growth patterns and historical documentation suggest that low intensity canopy disturbances (wind and snow) also caused mortality and diversified canopy structure. Because the stands developed naturally over the past 120+ years and thus escaped thinning operations, high volumes of coarse woody debris (94 m 3 ha −1 ) and snag densities (546 stems ha −1 ) have accrued. Advance spruce regeneration was quite abundant and existed primarily on deadwood substrates, even though these occupied only a small percent of stand area. Because of salvage logging in the late 1880s, these stands do not qualify, according to the traditional paradigm, as natural spruce forests. As a result, they are recently subject to active management practices including salvage logging that remove dead and dying trees. Given the importance of deadwood for forest regeneration and recovery from disturbance, as demonstrated in this study, we argue that dead wood removal may limit future natural regeneration in these stands. Thus, the purported benefits of removing dead and dying trees from semi-natural forests must be carefully weighed against the potential detrimental impacts on natural spruce forest regeneration and biodiversity.

Abstract Previous studies to explain why companies utilize particular human resource management (HRM) strategies have not adequately addressed the in uence of contextual variables such as size, location, ownership, competitive pressure, technological change, age and growth. In ...

Growth rates of New Zealand endemic longfinned eels (Anguilla dieffenbachii) from streams in pasture and indigenous forest, and from two hydroelectric lakes (Lakes Karapiro and Matahina), were estimated by otolith examination. Habitat-specific growth was further investigated with measurement of widths of annual bands in otoliths. Longfinned eels 170-1095 mm in length ranged between 4 and 60 years old (N = 252). Eels in pastoral streams grew faster (mean annual length increment ± 95% CL = 24 ± 3 mm to 36 ± 7 mm) than eels in streams in indigenous forest (annual length increment 12 ± 2 mm to 15 ± 3 mm). Eels from the hydro-electric lakes had growth rates (annual length increments 19 ± 4 and 19 + 7 mm) similar to eels from pastoral streams. Otoliths of most eels showed annual band widths that indicated growth in several different habitats, corresponding to growth during upstream migration, and limited movement among adult habitats. Estimated age at marketable size (220 g) ranged between 7 and 26 years. The particularly slow growth of longfinned eels in streams in indigenous forest has considerable implications for management. The fast growth rates of eels in hydro-electric lakes provides M92055

The otolith microstructure of Ceratoscopelus maderensis (Lowe) and C. warmingii (Luetken) was studied with light and scanning electron microscopy. The two species have a similar otolith structure consisting of a central core with outward radiating aragonite crystals forming increments. Growth increments were well defined over most of the sagittal sections of otoliths except in the transitional area around the core and outermost parts of the largest C. maderensb otoliths. The ages of 39 C. maderensis and 37 C. warmingii were estimated by enumeration of otolith increments that were postulated to be daily. The ages of an additional 40 C. maderensis were estimated from otolith weight through the use of a regression model. No differences in size of males and females were observed in C. maderensis while in C. warmingii females were larger than males. Ceratoscopelus maderensis was characterized by linear growth during the first 6 months of life, attaining over 40 mm SL at that age. A reduction in growth rate occurred at an calculated age of about 10 months and a size of 50 mm. This coincided with the winter season and sexual maturation. Only a few specimens over 2 years of age were observed, an indication of a high mortality during the second year of life, although sampling bias may have contributed to the lack of abundance of older fish. With this consideration, the growth parameters of the von Bertalanffy equation estimated for C. ~derensjs were R = 1.3 and L T = 79.0 mm. For the C. wurmingii samples analyzed, males attained lengths of 46-47 mm at 9-10 months of age, while females lived over 1 year and reached 64-68 mm. A noticeable decrease in growth in males was prominent at the larger lengths, whereas, the growth of females was linear to the maximum size captured.

The Pacific jack Caranx caninus is a common species fished by artisanal fishermen off the coast of Colima, México. During 2002, monthly samples of morphometric data and otoliths were taken to determine age and growth. Seven age groups were identified. The highest growth, 14.4 cm, takes place during the first year of life. During the second year, C. caninus grows 11.76 cm; the third year 9.61 cm; the fourth 7.85 cm; the fifth 6.41 cm and sixth year 5.24 cm. The constants of von Bertalanffy´s growth equation were: L ∞ = 83.26 cm, W ∞ = 18.138 g, K = 0.202, t o = -0.283 and A 0.95 = 15 years. Growth curves of other species of the same genus were calculated in order to compare them with the one obtained in the present work. The gonadosomatic index presented higher values during November and May. The periods of more intensive feeding are from August to February. Rev. Biol. Trop. 56 (1): 171-179. Epub 2008 March 31.

The purpose of this study was to validate vertebral band count ageing of juvenile shortfin mako (Isurus oxyrinchus) and to resolve the discrepancy between observed fast growth in juvenile shortfin mako and the much slower growth predicted by age-at-length models that assume one band pair per year deposition rate in vertebrae. Oxytetracycline (OTC) labeled vertebrae of 29 juvenile shortfin mako were obtained from tag-recapture activities to determine timing of centrum growth band deposition. Tagging occurred off southern California from 1996 to 2010, with time at liberty of the 29 sharks ranging from 4 months to 4.4 years (mean=1.3 years). Growth information was also obtained from length frequency modal analyses (MULTIFAN and MIXDIST) using a 29-year dataset of commercial and research catch data, in addition to tag-recapture growth models (GROTAG) using lengths and time-at-liberty for OTC-labeled and unlabeled shortfin mako. For vertebrae samples used for age validation, shark size at time of release ranged from 79 to 142 cm fork length (FL) and from 98 to 200 cm FL at recapture. Results from band counts of vertebrae distal to OTC marks indicate two band pairs (2 translucent and 2 opaque) are formed per year for shortfin mako of the size range examined. In addition, total band pair counts at length compared well with results of a similar study in this region, suggesting vertebral readings were similar, and only assumptions about deposition rate differed. Growth rates calculated from length frequency modal analyses estimate 26.5 to 35.5 cm per year for the first age class mode (85 cm FL), and 22.4 to 28.6 cm per year for the second age class mode (130 cm FL). In addition, the tagrecapture growth model also resulted in a rapid growth rate during time at liberty for tagged fish of the two youngest age classes with estimates of 28.7 and 19.6 cm FL per year at 85 and 130 cm FL, respectively. Collectively, these methods suggest rapid growth of juvenile shortfin mako in the southern California study area and suggest biannual deposition in vertebrae for the first five years.

Estimated ages of 1136 individual albacore Thunnus alalunga (57-92 cm L F ) from the Aegean and Ionian Sea ranged from 1 + to 9 years. Males grew faster and reached a greater size and age than females. No significant differences were found in the mean lengths at estimated ages between the two sampling areas. The von Bertalanffy growth model was fitted to mean lengths of estimated ages of individual fish and estimated growth parameters for the combined sexes were: L`=94·7 cm, K=0·258, to= 1·354 years. Significant differences were found when the Mediterranean albacore growth parameters were compared with those determined for Atlantic Ocean albacore. It is not possible to determine if the differences in growth rates for the two populations are phenotypic or genotypic at the present time. 2000 The Fisheries Society of the British Isles

Hadal trenches are isolated habitats that cover the greatest ocean depths (6,500–11,000 m) and are believed to host high levels of endemism across multiple taxa. A group of apparent hadal endemics is within the snailfishes (Liparidae), found in at least five geographically separated trenches. Little is known about their biology, let alone the reasons for their success at hadal depths around the world. This study investigated the life history of hadal liparids using sagittal otoliths of two species from the Kermadec (Notoliparis kermadecensis) and Mariana (Pseudoliparis swirei) trenches in comparison to successful abyssal macrourids found at the abyssal-hadal transition zone. Otoliths for each species revealed alternating opaque and translucent growth zones that could be quantified in medial sections. Assuming these annuli represent annual growth, ages were estimated for the two hadal liparid species to be from five to 16 years old. These estimates were compared to the shallower-living snailfish Careproctus melanurus, which were older than described in previous studies, expanding the potential maximum age for the liparid family to near 25 years. Age estimates for abyssal macrourids ranged from eight to 29 years for Coryphaenoides armatus and six to 16 years for C. yaquinae. In addition, 18 O/ 16 O ratios (δ 18 O) were measured across the otolith using secondary ion mass spectrometry (SIMS) to investigate the thermal history of the three liparids, and two macrourids. Changes in δ 18 O values were observed across the otoliths of C. melanurus, C. armatus, and both hadal liparids, the latter of which may represent a change of > 5 °C in habitat temperature through ontogeny. The results would indicate there is a pelagic larval stage for the hadal liparids that rises to a depth above 1000 m, followed by a return to the hadal environment as these liparids grow. This result was unexpected for the hadal liparids given their isolated environment and large eggs, and the biological implications and plausibility of interpretations of these data are discussed. This study presents a first look at the life history of some of the deepest-living fishes through otolith analyses.

Age and growth of the school shark Galeorhinus galeus was studied from rings in the vertebra and length-frequency data. Samples were collected by trawling off the southern Brazilian coast from June 1980 to September 1986. Histological studies were also conducted on the characteristics of the vertebra. Standard histological techniques and microradiography were used to determine the pattern of vertebral calcification. The vertebrae of G. ga,.

Phytosociological sampling, structure, age and growth rates studies were carried out in 5 places of Dangam District of Afghanistan. Vegetation compositions of non tree species were also presented. On the basis of floristic composition and importance value index of tree species, two monospecific and one bispecific communities were recognized in the study area. It is shown that in Picea smithiana (Wall.) Boiss., Dbh, age and growth rates are not significantly correlated. Lack of tree seedlings indicate poor regeneration status of the forests.

The effects of age and external factors on preen gland morphology and feather lipid concentrations in layer fowl (Gallus domesticus) have not previously been described. This work examines how floor substrate, whether a bird is feather pecked or not, and age influence both gross and histological morphology. Furthermore, the effects of age, beak trimming and floor substrate on feather lipid concentration (mg lipid per g feathers) are investigated. Neither absolute nor relative preen gland weight were reliably affected by floor substrate or feather pecked status. However, these parameters were strongly affected by changes in bird age and related body weight changes. The microstructures of the gland also increased consistently with age. Feather lipid concentration generally increased with age. Feather lipid was strongly influenced by the presence or absence of a dustbathing substrate. Of all the parameters tested here, the age and growth of the bird had the greatest effects on preen gland development. Feather lipid concentration is also influenced by age, and by the presence or absence of a dustbathing substrate. ᮊ