Age, growth and reproductive parameters of the Mediterranean cardinal fish, Apogon imberbis

Life history parameters (age, growth and reproductive characteristics) of the Mediterranean paternal mouthbrooding cardinal fish, Apogon imberbis, were investigated at a coastal locality off Blanes, NW Mediterranean Sea. Maximum age was found to be 5 years for both sexes. Age was validated with an otolith chemical (tetracycline) marking experiment. Both females and males reached maturity at length >5.5 cm, corresponding to 1 year of age in both sexes. The spawning season ranges from July to October, with a peak in August. The number of eggs in the mouths of males increased linearly with fish total length.     

The biology of the scaldfish, Arnoglossus laterna (Walbaum) on the west coast of Scotland.

The biology of a Scottish population of the small bothid flatfish, Arnoglossus laterna , was studied from January 1975 until September 1976. The data were taken from monthly samples totalling over 500 fish trawled in 18–36 m on a soft mud bottom. Otoliths were used for age determination and a growth curve was constructed which showed that most growth occurs in the first 2–3 years of life. The maximum age recorded was 8+ years. The fish first mature sexually in their second year at a standard length of 6–7 cm and the short spawning season lasts from the late June to August. Fecundity is length-dependent and the relationship could be described by the regression equation: log fecundity = 3·3472 log standard length (mm) -2·1064. The diet consists mainly of decapod crustaceans (particularly crangonid shrimps), polychaetes, mysids and small fish.     

Otolith microstructure reveals consequences for juvenile growth of fractional spawning in an invasive goldfish Carassius auratus (Linnaeus, 1758) population

The consequences of fractional spawning on the early‐life growth rates of invasive goldfish (Carassius auratus) from the Qinghai‐Tibet Plateau were studied using the otolith microstructure of samples collected in June 2011. The effect of the estimated hatching date on the subsequent growth of individual fish was determined by back‐calculating their number of growth days, daily growth rates and the onset of their second growth season. The number of growth days in the first growth season ranged from 93 to 186 days. Following hatching, daily growth rates increased rapidly to a maximum of 0.55 mm days^?1 before declining to 0.09 mm days^?1. The effect of the duration of the first growth season on individuals was significant (P < 0.01), with later spawned fish having faster growth rates. These later spawned fish were, however, still significantly smaller in body length at the end of the first growth season (37 ± 4 mm in late hatched fish vs 55 ± 9 mm in early hatched fish). However, the smaller, later hatched fish started growing earlier in their second growth season than all other fish (P < 0.01) and subsequently achieved larger growth increments (P < 0.01), suggesting that the larger, early‐hatched fish were investing more resources in gonadal growth than somatic growth in their second growth year. Thus, this invasive population revealed considerable plasticity in their early‐life growth rates that were associated with the hatching date, potentially having substantial effects on their development in their second year of life.     

The record of daily growth in otoliths of Atlantic silversides, Menidia menidia, from field and laboratory

Otoliths were removed from field-collected silversides of age less than 3 months. Otolith diameter was highly correlated with total length of the fish. Daily growth ring counts for this species are known to be a function of age rather than size, so widths for the daily growth rings provide a record of daily increases in length of the fish. Measurement of ring widths showed that weekly specific growth rate was greater than 70% at age 1 week, but declined to about 30% at age 1 month and about 15% at age 2 months. A laboratory experiment in which temperature was changed on a weekly basis demonstrated that environmental variables can affect the width of rings. Nevertheless, the growth rate of field-collected fish, as calculated from otolith ring widths, was more highly correlated with size of fish, as measured by otolith radius, than with the environmental variables of temperature, salinity and plankton abundance. Back-calculation of growth rates from otolith ring widths of five fish collected at the end of the growing season yielded the same age-growth curves as were obtained from 203 fish collected biweekly during the season.     

Using otolith weight to age fish

The problem of determining and verifying ages of fish, from populations having a considerable variation in size at age, has been investigated using the relationship between otolith size and fish size, which has been shown by several authors to be influenced by growth rate. In such a population of Sardinella aurita Val. an index of age can be obtained for individual fish by calculating the equivalent otolith weight at a particular fish length, using the otolith weight–fish length relationship determined for each age group. This statistic not only permits a much greater proportion of fish to be assigned ages than is possible with otolith reading alone, but also enables the age groups to be verified as year classes. However, it is concluded that, although appropriate models based on otolith-fish size relationships can predict age for groups of fish in which growth rates are known or can be assumed to be consistent, such techniques have a limited application in ageing fish from wild populations with highly variable growth rates.     

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.     

The first annulus of otoliths: a tool for studying intra-annual growth of walleye pollock (Theragra chalcogramma)

We quantified the growing season of yearling walleye pollock (Theragra chalcogramma) and related it to annual cycles of water temperature and day length. The study was restricted to members of the 2000 year class and thereby controlled for inter-annual variability. Juveniles were sampled from the year class during 10 cruises in the western Gulf of Alaska (GOA). Fifty percent of juveniles exhibited an annulus on 16 March 2001 (± 11 days 95% confidence interval). No regional difference was detected in the timing of annulus formation or in post-annulus growth trajectories. A model, derived from growth trajectories, estimated that the growing season lasted 204 days (22 March to 13 October 2001) and that growth rate peaked at 0.59 mm day⁻¹ on 2 July 2001. Growth rate increased with day length and water temperature during spring and decreased in late summer possibly due to thermal stress. Secondarily, we explored the utility of otolith size at the first annulus as a natural tag to identify nursery area, but this potential was curtailed by overlap in length among regions. Our results indicate that the first annulus can be used to advance our understanding of climate forcing on marine fish growth by providing fine temporal resolution of the growing season.     

Ecological aspects of the Japanese eel, Anguilla japonica, collected from coastal areas of Japan

The ecological characteristics of 597 yellow and silver-stage Japanese eels, Anguilla japonica, were examined and compared among collection sites located at three different latitudes of Japan (Amakusa Islands, Mikawa Bay, and Sanriku Coast) to provide basic data on this unusual catadromous fish species. Eels were sexed and their total length, body weight, age, and growth rate based on otolith analysis was compared among sexes, stages, and collection sites. The overall sex ratio favored females (94%), but the sex ratio differed among the three locations. The frequency of females was highest in the coastal waters at Sanriku in the north (100%), next highest at Mikawa Bay in central Japan (95%), and lowest in the Amakusa Islands in the south (70%). Silver eel males ranged from 41.2-66.3 cm in length and 4-10 years in age, and silver eel females from 44.3-97.2 cm in length and 5-17 years in age. Female eels generally grew faster (8.7+/-2.2 cm/year) than males (6.4+/-2.6 cm/year), and the growth rate slowed in the older eels. The growth rate of A. japonica at all three sites was much faster than that of other temperate anguillid species (< 4 cm/year), and their age at maturation was younger than that of other temperate species (approximately 7 to > 50 years), suggesting this species has important ecological differences from other similar species.     

Otolith and somatic growth rates in Atlantic salmon parr, Salmo salar L: evidence against coupling

It is often assumed that otolith growth is in some way dependent on somatic growth (i.e. that the two processes are coupled). We examined the relationships between sagitta radius and fork length in 0+ Atlantic salmon parr that would subsequently smolt aged 1 + (UMG fish) or 2+ (LMG fish). Repeated measurements of fork lengths of individually marked parr, taken over a 211-day period from first feeding, were compared to sagitta radii on the same measuring dates (obtained by analysis of daily increments). The results showed that there was a linear relationship between fork length and otolith radius in UMG parr. However, this was not true for LMG parr. These fish enter a state of natural anorexia in their first autumn (despite excess food), but their otoliths continued to grow at the same rate despite the virtual cessation of somatic growth; they had therefore developed disproportionately large otoliths by the end of the study period. The relative growth rates of soma and otoliths first changed in LMG fish in late July/early August; this is the most precise estimate yet obtained of the timing of divergence in the developmental pathways of UMG and LMG parr. The rate of sagitta accretion was consistently lower in LMG parr, possibly indicating a lower metabolic rate in these fish. The results are discussed in relation to previous theories of the relationship between otolith and somatic growth.     

BOOK REVIEWS

SUMMARY

Scale studies indicated that the annulus is a reliable year mark. A linear relationship existed between scale radius and body growth enabling back calculations to be made. The growth rate of males in Doorndraai Dam were similar to findings in the Incomati and Limpopo systems by Gaigher 1969 and Potgieter 1974 for the same species. The average sex ratio was one male to 1,8 females and was similar to that of the above river systems. Males reached sexual maturity at 12 cm while females matured at a length of 15 cm. The spawning season extended from late September to after December. Fecundity increased with an increase in length from 3 600 ova for a 15,4 cm fish to 8 500 for a 30,9 cm fish. T. rendalli fed extensively on macro-phytic vegetation when it was available, otherwise they became facultative feeders.     

Seasonal pattern of filial cannibalism by Apogon doederleini mouthbrooding males

In temperate waters of southern Japan, mouthbrooding males of the cardinal fish Apogon doederleini sometimes ate their entire brood within a day of spawning. In spite of annual variation in age structure and length of the breeding season, however, the annual cannibalism rate (broods cannibalized to total broods spawned) was nearly constant, 12–16%. Fish 1 year old frequently cannibalized early broods of the season, especially the first brood, whereas the cannibalism rate by 2 year-old fish did not vary within the season. In contrast, the cannibalism by older males increased late in the season. This tendency was attributed to their different allocation patterns to growth and reproduction. For 1 year-old fish, which can enhance future reproductive success by growth and cannibalizing on early broods instead of mouthbrooding (at relatively low temperatures), this may be a tactic for investing energy in growth. For fish 3 years, which have more breeding cycles and grow little, cannibalizing late broods may be energetic compensation for their poor somatic condition. No seasonal variation of cannibalism by 2 year-old fish can be explained by their intermediate nature of growth and reproduction. Multiple mate availability is one factor facilitating the cannibalism by 2 and 3 + year-old fish whose operational sex ratio is female-biased.     

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.     

Estimation of migratory history in female masu salmon Oncorhynchus masou (Brevoort, 1856) with the growth hormone pseudogene

To estimate the migration timing, length, and location of females with the growth hormone pseudogene (GHp), trace element analyses were performed on the otoliths of 40 wild adult masu salmon, Oncorhynchus masou (12 males, 19 normal females, and nine females with GHp [all fish were 3‐ or 4‐years‐old]) caught during the reproductive season (September) from 2004 to 2010 in the Atsuta River in Japan. Sr concentrations at the end of the otolith translucent area formed during the winter suddenly increased in all individuals, suggesting that they had migrated in the spring. In addition, the estimated migration length and location of females with GHp indicated that they had spent a fixed period of 1 year in the ocean, suggesting that females with GHp have a similar migratory history as that of normal females.     

Onset of maturity and cohort composition at spawning of Baltic sprat Sprattus sprattus on the basis of otolith macrostructure analysis

Data on catch per unit effort (CPUE) from the Danish commercial fishery showed dense aggregations of sprat Sprattus sprattus born in 1997 in the main spawning area of the Baltic Sea during May 1999. After the analysis of their otolith macrostructure, these fish were found to have a shorter distance to the beginning of the first winter zone compared to fish from the same cohort caught in other months. At the same time, the number of fish with large otoliths at the period of winter zone formation tended to decrease or even disappear. The otolith size at winter zone formation ( O _W) was found to be a good predictor of sprat total length ( L _T) and mass ( M ) in age group 0 years. Changes in the otolith size distribution over time were related to variations in cohort composition depending on the L _T and M attained during the juvenile stage. Examination of the gonads suggested two life history patterns: 1) individuals achieving a larger L _T and M during the first growing season may contribute at age 1 years to the spawning stock and the fishery, whereas 2) individuals attaining smaller L _T and M contribute in larger amounts to both the spawning stock and the fishery later, when they are at age 2 years. Moreover, changes in the relationship between O _W and L _T and M were related to differences in growth trajectories for sprat born during the same spawning season. Smaller sprat as group 0 years continued growing during the second growing season delaying maturity compared to larger individuals from the same cohort.     

Age and growth of the porthole shovelnose catfish (Hemisorubim platyrhynchos) in the Pantanal.

The porthole shovelnose catfish, Hemisorubim platyrhynchos, is the sixth largest pimelodidae of the Pantanal. Its age and growth were studied using pectoral fin-spines from fish collected in the Cuiabá river basin, Pantanal. The fish, which came from commercial and experimental fisheries, were all caught with hook and line. Growth-ring formation time could not be defined through the Kruskal-Wallis test on marginal increment (H = 4.142; p = 0.247). Nevertheless, decrease in the marginal increment index occurring as waters recede suggests this as the probable time when growth rings form. Estimation of the parameters of von Bertalanffy growth curve, adjusted through nonlinear regression to observed fork lengths, with L(infinity) fixed at 64 cm, were: k = 0.222 year(-1); t(o) = -2.149 years. Individual life span was estimated at 11.4 years. The results suggest that fork length is a good predictor of age for individuals of this species.     

Sexual dimorphism in the otolith shape of shi drum,Umbrina cirrosa (L.), in the eastern Mediterranean Sea: Fish size–otolith size relationships

Little is known about possible differences in sagitta otolith size and shape between sexes of the shi drum, Umbrina cirrosa, and relationships between their body and otolith size. Thus, this study aimed to fill this knowledge gap via examination of 414 sagittal otoliths from 108 male (total length 13.8–26.8 cm) and 99 female (13.5–26.7 cm) U. cirrosa caught between May 2017 and April 2018 in gillnets set at a depth of ~15 m in Mersin Bay, Eastern Mediterranean Sea. No statistical differences were observed between the shape indices of the left-sided and right-sided sagitta. However, there were significant differences in the size and shape of otoliths between males and females. The slopes of allometric power functions from otolith width × fish sizes gave significant differences between males and females (ANCOVA, P < 0.05). The relationship for length × weight of otoliths from both males and females showed isometric growth, whereas the relationship of otolith width × otolith weight showed positive allometry. Negative allometric growth was observed for the relationship otolith length × otolith width. In summary, this study revealed the presence of sexual dimorphism in the otolith shape of U. cirrosa, and the data on regression relationships of fish-otolith sizes can be used to estimate fish size from U. cirrosa otolith sizes.     

Comparison of otolith growth and morphology with somatic growth and age in young-of-the-year bluefin tuna

Otolith morphological characteristics were studied using image analysis techniques and the relationships between otolith growth and somatic growth and age, as estimated from counting daily otolith increments, were examined in young-of-the-year (YOY) bluefin tuna Thunnus thynnus ranging in fork length ( L _F) from 8·5 to 55·5 cm. Whole otolith length, width, area and perimeter, and three shape indexes, circularity, E value and rectangularity, were extracted for each pair of sagittae. Since no statistical significant differences between left and right otolith morphometrics were found, only one otolith from each fish was used for correlations. Statistically significant relationships were observed between otoliths measurements and fish somatic growth when a linear regression was applied after logarithmic transformation of all variables tested. Among the variables, otolith length was the one that showed the highest correlation with L _F, followed by otolith area and perimeter, whereas otolith rectangularity exhibited the lowest correlation. Statistically significant relationships were also observed between the otolith variables tested and the age of the fish, which ranged from 20 to 129 days. The ages estimated using otolith mass were very close to those assessed using daily increment counts (bias ranged from 1 to 24 days). Therefore, otolith mass could represent a valuable criterion for age estimation in YOY bluefin tuna that is objective, economic and easy to perform compared to daily increment counting method.     

Age and growth of albacore Thunnus alalunga in the North Pacific Ocean

The age and growth of North Pacific albacore Thunnus alalunga were investigated using obliquely sectioned sagittal otoliths from samples of 126 females and 148 males. Otolith edge analysis indicated that the identified annulus in a sagittal otolith is primarily formed during the period from September to February. The assessments of the fish age at first annulus formation indicated that the first annulus represents an age of <1 year. This study presents an age estimate (0·75 years) for the formation of the first annulus. The oldest fish ages observed in this study were 10 years for females and 14 years for males. The von Bertalanffy growth parameters of females estimated were L(∞) = 103·5 cm in fork length (L(F) ), K = 0·340 year(-1) and t(0) = -0·53 years, and the parameters of males were L(∞) = 114·0 cm, K = 0·253 year(-1) and t(0) = -1·01 years. Sexual size dimorphism between males and females seemed to occur after reaching sexual maturity. The coefficients of the power function for expressing the L(F) -mass relationship obtained from sex-pooled data were a = 2·964 × 10(-5) and b = 2·928.     

The relationship between otolith size and estimated age of tigertooth croaker (Otolithes ruber Bloch and Schneider, 1801) in Oman Sea,Iran

The relationships between somatic growth and otolith dimensions, otolith size to estimated age and growth parameters of the tigertooth croaker (Otolithes ruber) were investigated in 100 specimens (size range: 19.1–52.0 cm, total length) from the Oman Sea area, September 2014. All 100 otoliths were sectioned and determined by age. The oldest specimen was a 4.5‐year‐old female with a total length of 40.6 cm; the youngest specimen was also a female estimated at 1 year of age with a total length of 19.1 cm. The von Bertalanffy growth equation was estimated as L_t = 54.70 (1 ? exp (?0.37 (t + 0.21))). Concluded was that there is a significant relationship between body size, otolith dimensions and estimated age of Otolithes ruber.     

Otolith length/fish length relationship of leptocephali,elvers, and sub-adult (reared) eelsAnguilla anguilla

Synopsis The otolith length and the total fish length of 9 leptocephali, 29 elvers and 51 sub-adult eels were measured. For the 51 eels a significant correlation between otolith and fish length was found. No similar correlation was found for leptocephali and elvers because of their similar total length. It was found that the growth of the otolith from leptocephali and elvers differs from the growth of herring larvae otoliths.