Increment Deposition Rate Research Articles

Staining protocols affect use of otolith to estimate the demography of the damselfish sergeant major (Abudefduf vaigiensis).

This study assessed the otolith (sagittae, lapilli, and asterisci) increment deposition rate in the range-shifting damselfish, A. vaigiensis, using different concentrations of Alizain Red S and evaluated the impact of staining on increment width. Daily increment deposition was verified in all otolith types and presented clearer fluorescent markings in the lapilli and sagittae than the asterisci, with high stain concentration showing the best clarity. Higher stain concentrations were found to decrease increment width, suggesting care is needed when using stained otoliths as a proxy for growth for this species.

Evaluating otolith increment deposition rates in bigeye tuna (Thunnus obesus) and yellowfin tuna (T. albacares) tagged in the Atlantic Ocean

Evaluating otolith increment deposition rates in bigeye tuna (Thunnus obesus) and yellowfin tuna (T. albacares) tagged in the Atlantic Ocean

Growth and Microstructural Features in Otoliths of Larval and Juvenile Sinogastromyzon wui (F. Balitoridae, River Loaches) of the Upper Pearl River, China

Otolith growth and microstructural features of fish are essential to the understanding of the early fish lifecycle. This paper assesses the features of otoliths from laboratory-reared larval and juvenile Sinogastromyzon wui (S. wui, 0 to 25 days post-hatching) that were obtained as eggs from the Shilong Reach of Xijiang River between April and August 2021. We observed the development of the three pairs of otoliths (lapilli, sagittae, and asterisci) and compared the shape changes and growth of the lapilli and sagittae, as well as the timing and deposition rate of increments of the lapilli. The lapilli and the sagittae were visible on hatching, whereas the asterisci were present at four days post-hatching (dph). The shape of the sagitta changed more obviously than that of the lapillus, and a strong correlation was observed between sagitta shape changes and fish ontogenesis. The otolith shape greatly modulated during the post-flexion larval stage (Post-FLS), it corresponded with the formation period of individual fins. Analysis of the microstructural features indicated that lapilli were the optimal otolith for age determination and increment deposition rate confirmation. Using regression analysis of the known age and the number of lapillus daily increments, we demonstrated that the lapillus developmental increments were deposited daily, and the first increment formed at two days post-hatching. Our conclusions support employing the lapillus increment deposition rate and the time of the first daily increments in the determination of the age of wild larval and juvenile S. wui.

Otolith shape analysis and daily increment validation during ontogeny of larval and juvenile European chub Squalius cephalus.

This assesses features of otoliths from laboratory-reared embryos, larvae and juvenile European chub Squalius cephalus from hatching to 180 days post-hatching (dph). We observed the development of the three pairs of otoliths (lapilli, sagittae and asterisci) and more precisely shape changes, as well as timing and deposition rate of increments of the lapilli. The lapilli and the sagittae were present at hatching, whereas the asterisci formed between 20 and 30 dph. The lapillus and sagitta shapes were round until 20 dph. From 60 dph the anterior and the posterior rostra of the sagittae were well developed, but very thin, making this otolith too fragile to manipulate for further studies of shape and validation of otolith increment deposition rate. The lapilli provided reliable age estimates for free embryos, larvae and juveniles up to 120 dph. However, caution should be taken when ageing fish older than 150 dph as an underestimation was noticeable. The regression of the number of otolith increments on age showed a slope and an intercept not significantly different from 1 and 0, respectively, which indicated that otolith growth increments were deposited on a daily basis, with the first microincrement occurring at hatching. Increment counts were consistent between three interpreters, indicating a consistent and reliable age estimate. This study validates that the otolith increment deposition rate can be used to assess hatching dates and daily growth of wild S. cephalus under 150 dph and in environments similar to the conditions used in this study.

Validation of the first annual increment deposition in the otoliths of European anchovy in the Bay of Biscay based on otolith microstructure analysis

In order to validate the first annual increment deposition in European anchovy otoliths, early juveniles were captured in October 2012 in the southern Bay of Biscay. These individuals were maintained under a continuous feeding regimen in a sea cage over a period of 6 months. From October 2012 to January 2013, lengths increased slightly or remained stable at ~9.8cm. After this period, standard length increased significantly up to a mean value of 12.0cm in April 2013. Likewise, the age of anchovies was estimated based on otolith microstructure analysis. The estimated age varied from 96 days (for individuals sampled in October 2012) to 293 days (for anchovies sampled in April 2013). A daily increment deposition rate was confirmed in otoliths of individuals maintained in the sea cage during the winter. The general otolith daily growth pattern showed that increment widths increased rapidly and were broadest between 51 and 56 days, with a mean of 19.1µm. Thereafter, the widths decreased steadily to 1.5µm and remained almost constant until the end of the experiment. The present study also revealed that the first translucent band formation started in autumn and was completed by spring.

Effects of temperature, starvation and photoperiod on otolith increments in larval Chinese sucker, Myxocyprinus asiaticus

Effects of water temperature, starvation and photoperiod on otolith increment formation in larval Chinese sucker, Myxocyprinus asiaticus, were examined in this study. The results demonstrated that otolith increments of larvae reared under diel temperature fluctuations were very clear and appeared with a high contrast, while those of larvae raised under constant water temperatures were vague or hard to identify. The increment deposition rates were less than 1.0/day in later stage of starvation period. Also, increment deposition was affected by cyclic regimes of water temperature fluctuations, the number of increments corresponded to the cycle times rather than the exact days larvae experienced. However, varying of feeding frequency and photoperiod did not result in any alterations of daily increment formation. Increment width increased obviously with higher rearing temperatures till several days after yolk absorption. However, the width presented an ontogenetic decline during period of endogenous nutrition and the first several days of exogenous nutrition stage. Starvation decoupled the relationship between somatic growth and otolith growth; otolith kept growing, and increment width of starved larvae was similar to those in fed individuals before 9–20 days old; the divergence of increment width from the fed larvae occurred in later stage of starvation period. It can be concluded that temperature regimes and food levels are the major factors affecting increment formation in terms of clarity, deposition rate and width, while photoperiod and feeding frequency have less influence on it.

Validation of daily increments deposition in the otoliths of European anchovy larvae ( Engraulis encrasicolus L.) reared under different temperature conditions

European anchovy eggs ( Engraulis encrasicolus L.) were hatched and larvae reared in the laboratory in order to validate the daily increment deposition in otoliths under different temperature condition. Additionally, the effect of temperature on otolith and larval growth and on the fish length and otolith radius relationship was also analysed. On sagittae, one to four increments can be depositioned during the embryonic stage and the first regular increment was formed the day after hatching. Temperature was found to have a significant effect on the increment deposition rate and otolith growth. A daily increment deposition rate was confirmed in larvae reared under conditions of higher temperatures (20.8 and 22.3 °C), while the apparent rate of increment formation of larvae reared at 17.6 °C was clearly lower. Standard length and otolith radius were closely related and this relationship was affected by both temperature and growth rates. The implications of the effect of these variables on otolith growth are further analysed in relation to non-daily pattern of increment deposition found at the lowest temperatures.

Temperature-dependent otolith growth in Norwegian spring-spawning herring (Clupea harengus L.) larvae

Norwegian spring-spawning herring larvae ( Clupea harengus L.) were reared at different temperature combinations in the laboratory, and marked twice with a fluorescent dye, alizarin complexone, to estimate otolith growth and increment deposition rate. A daily increment deposition rate was confirmed in the sagittae of larvae reared at 12 °C from day 16 (first marking age), while the apparent rate of increment formation of larvae reared at 4 °C was clearly less than one per day. A reduction in rearing temperature from 12 to 8 °C between days 16 and 30 (second marking age), significantly affected sagitta growth during the inter-mark period compared with those reared at 12 °C throughout. Similar somatic growth rates were observed in both groups temporarily reared at 8 °C between markings (about 6% day −1 ), but the otolith growth rate was more than four times higher in the group originating from 12 °C compared with the one originating from 4 °C. The body size versus otolith size relationship was temperature d...

Laboratory validation of periodicity of incrementation in statoliths of the South African chokka squid Loligo vulgaris reynaudii (d'Orbigny, 1845): a reevaluation

The periodicity of increment formation in statoliths of the South African chokka squid Loligo vulgaris reynaudii (d'Orbigny, 1845) is tested using the results of laboratory statolith marking experiments. Statoliths of live squid were marked by oxytetracycline injection, and the squid released into tanks in the laboratory. Two of the squid survived for a sufficient period to permit the application of a second mark. The statoliths were extracted from squid recaptured after a known period and prepared for examination by light and UV fluorescence microscopy. Statoliths from 102 squid were obtained from the experiment, of which 75 (36 males and 39 females ranging from 1 to 29 days postmarking) were successfully prepared for examination. Three replicate counts of the number of increments deposited after marking were recorded from each statolith. The quality of each statolith preparation was quantified during each replicate reading, and these values were used to filter the data to exclude the results from average and below average preparations. The statoliths of 16 squid fulfilled the filtering criteria (11 males and 5 females, 1–29 days and 1–13 days postmarking, respectively). Replicate increment counts were felt to be adequately precise to use the mean increment count as an estimate of the number of increments deposited after marking. The daily increment hypothesis was tested using simple linear regression and statistical power analyses. The data obtained from good statolith preparations strongly support the daily increment hypothesis, although this conclusion should be treated with caution with regard to female squid. Estimates of the statistical power of the conclusions were relatively low, primarily as a result of small sample size. Increment deposition rates in male chokka squid in the laboratory were comparable to those of male squid in a previously reported field study, suggesting that the results of laboratory experiments can be extended to squid in the wild. A possible difference in the readability of statoliths between the sexes is apparent and requires further investigation.

Differential increment-deposition rate in embryonic statoliths of the loliginid squid Loligo vulgaris

Apart from one study that reported growth of less than one increment per day in statoliths of the squid Alloteuthis subulata, most studies so far have presumed that one increment was laid down per day in the statoliths of the squid species they examined. The present study provides evidence of differential daily growth rates in embryonic statoliths of the squid Loligo vulgaris Lamarck, 1798, thus confirming a previous report for A. subulata. Incremental growth rates of L. vulgaris statoliths differ as a function of temperature. Squid embryos were incubated in the laboratory at three temperatures (12.0, 15.5 and 21.1 °C), and tetracycline staining was used to follow statolith growth. This growth slowed in squid exposed to the lowest temperature, but recovered when the squid were returned to warm conditions, indicating statolith adaptation. Statolith growth rate after incubation at 12 °C was 1.3% d−1 and reached 6.1% d−1 for squids exposed to 21.1 °C. Statoliths from embryos incubated at 15.5 °C yielded a rate of 1 increment d−1 and a mean daily growth of 2.2 μm in the dorsal dome area of the statolith. In contrast, the slow growth of statoliths incubated at 12 °C yielded a mean daily growth of only 0.9 μm in the dorsal dome and the readings resulted in a less-than-daily increment-deposition rate.

Growth-dependent age estimation in herring ( Clupea harengus L.) larvae

A controlled laboratory experiment was carried out to investigate growth-dependent otolith increment formation in herring larvae under constant and variable feeding regimes. Larvae of Norwegian spring-spawning herring were reared at 8°C for 46 days using nominal prey densities of 40 (low) or 1200 (high) prey l −1. Two groups of larvae were offered constant prey levels throughout the experiment (high or low), whereas the prey levels in two other groups were temporarily increased or decreased. All groups were marked twice with alizarin complexone immersion when prey levels were changed (day 18 and day 32 post hatching). Overall survival in the experiment ranged from 36 to 51%, and daily growth in length ranged from 0.02 to 0.4 mm per day. Average daily otolith growth (sagitta) in the low-prey-density group was below 0.2 μm per day, and the apparent increment formation rate was significantly below 1 per day. The high-prey-density group had an increment deposition rate of about 1 per day after the first marking, and these increments averaged 1.1 μm in width. The alizarin marking confirmed that otolith growth responded to increased prey densities and larval growth within a few days, but the response to deteriorating feeding conditions was slower. The apparent increment deposition rate was below 1 per day during the inter-mark period at average otolith growth rates of less than 1 μm per day. In the present study the increment deposition rate was correlated both with larval growth and larval size. The otolith growth pattern confirmed that there was a high correlation between larval size at sampling and previous larval size both within and between groups ( r s>0.6 after 4 weeks). The ratios of otolith sizes at different ages within individual larvae could be used to identify groups of larvae and to a large extent also individual larvae originating from different prey regimes.

Age validation and growth of yolked larvae of <em>Patagonotothen tessellata</em> (Richardson, 1845) (Pisces: Nototheniidae) from the rocky littoral of the Beagle Channel, Argentina

Age and growth estimation of Patagonotothen tessellata larvae over the endogenous period was estimated by examining their otolith microstructure and the associated increment deposition rate. Analyzed specimens were incubated from egg-masses collected in Lapataia Bay, Beagle Channel, Argentina. Validation was performed by monitoring reared larvae of known ages. Actual age and increment count were regressed suggesting a daily deposition of one ring in the otolith, which began at hatching time and continued until larvae reached sixteen days old (time of massive mortality). Mean lengths at each age were estimated using Richards´ growth function; their constant (m) attained a value close to zero indicating that the data fitted to the von Bertalanffy model. Absolute growth rate was 0.55 mm*d-1of total length at hatching, dropped near zero on the fifth day after hatching and afterwards, there was no growth. Yolk absorption rate (expressed as a ratio between minor axis/major axis of the vitelline-sac) showed a similar variation as that observed in absolute growth rate during the endogenous period. The total yolk absorption took five days in the unfed larvae group and seven days in the fed larvae group. The rapid absorption of the yolk and the observed growth pattern suggest that Patagonotothen tessellata larvae have a short endogenous period, reaching the state of first food uptake five days after hatching.

An otolith-based back-calculation method to account for time-varying growth rate in rainbow smelt (Osmerus mordax) larvae

This study develops a new back-calculation method, based on the larvae of rainbow smelt (Osmerus mordax), that takes into account the variation of growth rate over time. Known-aged larvae were reared in four 60-L microcosms during 49 days in order to obtain a large range of individual growth trajectories. We first validated the daily nature of the otolith increment deposition rate. The proposed time-varying growth (TVG) method weights the contribution of each increment in the length calculation using a growth effect factor. A small growth increment contributes less to the length increase of larvae than its relative importance in total otolith growth. On the other hand, a large growth increment contributes more to the length increase of larvae in comparison with its relative importance in total otolith growth. This method provided significantly better estimates of previous length-at-age than the biological intercept (BI) method at the individual level. In addition, the TVG method tended to provide more accurate estimates of previous length-at-age than the BI method at the population level, but the difference was not significant. The importance of using the TVG method instead of the BI method to back-calculate individual and population growth trajectories increases with the magnitude of the growth effect and the variation in growth rates over time.

Comparison of growth rate and formation of otolith increments in age-0 red snapper

For wild red snapper Lutjanus campechanus, mean otolith increment deposition rate after marking with oxytetracycline dihydrate (OTC) was daily (0.97 increments day−1) when growth rates were fast (0.63 mm fork length, LF day−1), but were not daily (0.82 increments day−1) when somatic growth was slow (0.2 mm LF day−1). For reared larvae (n=8), increment deposition rates were daily (0.99–1.03 increments day−1), and growth rates ranged from 0.6 to 0.9 mm LF day−1. Growth rate affected increment deposition rate as a threshold function, i.e. when growth rate was <0.3 mm LF day−1, deposition was less than daily, but above this level increment deposition did not exceed a daily rate. As growth rates increased increment widths increased. Examination of a sub-sample (n=8) of the otoliths from the slowest growing wild fish by scanning electron microscopy did not increase increment counts. Because L. campechanus are late spring-early summer spawners, young fish can expect maximum growth due to warm summer temperatures. Thus, daily ageing methods should be well suited to this species.

Validation Studies of Daily Increment Formation for Larval and Juvenile Summer Flounder, Paralichthys dentatus

The increment deposition rate in sagittal otoliths of larval and juvenile summer flounder, Paralichthys dentatus, was influenced by growth rate. Larvae of known age showed less-than-daily increment deposition during slow growth (0.1 mm∙d−1), but increment deposition appeared daily after the growth rate increased to 0.4 mm∙d−1. There was no significant difference between counts from larval otoliths made by either scanning electron microscopy or light microscopy. Juveniles collected in the field that were tetracycline marked and held in the laboratory at elevated temperatures (≈15 °C) showed significantly faster growth rates (0.3 mm∙d−1) and daily increment depositon rates compared with growth rates (−0.03 mm∙d−1) and less-than-daily increment deposition rates at ambient temperature (1–11 °C). Tetracycline-marked juveniles, held in cages in a subtidal creek, also showed daily increment deposition. Scale circuli were not deposited daily in the juveniles examined. It appears that daily aging of the youngest P. dentatus larvae is problematic, but after settlement in estuarine nursery areas, increment formation occurs daily.

Factors influencing otolith increment formation in Japanese eel,Anguilla japonica T. &amp; S., elvers

To determine the effect of environmental factors on otolith increment deposition in Japanese eel, Anguilla japonicaT. &amp; S., a total of 337 elvers with a tetracycline time mark in the otolith were reared for 50 days under various experimental temperatures (12, 19 and 25°C), feeding rations (fed and unfed) and salinities (one‐third sea water of I 2k and fresh water). Fish were sequentially sampled after 5. 15, 30 and 50 days and their sagittal otolith increments were observed. Under fed conditions at 19 and 25°C, daily increment deposition was observed throughout the 50‐day period. In unfed groups and/or at 12°C, the rates of increment deposition were reduced sharply after the fifth day and no clear increments were added. No difference was obtained in increment deposition rates between one‐third sea water and fresh water groups. Increment deposition rate was independent of otolith and body size.

The effects of feeding periodicity and ration on the rate of increment formation in otoliths of larval walleye pollock Theragra chalcogramma (Pallas)

The effect of feeding conditions (periodicity and ration level provided) on otolith increment counts of laboratory reared larval walleye pollock Theragra chalcogramma (Pallas) was tested. Increments were deposited with daily periodicity for larvae growing under optimal feeding conditions (high, continuous ration). Increment counts determined by light microscopy were less than expected, assuming a rate of formation of 1 · day −1 for larvae grown at low rations. Increment deposition and length (and therefore growth rates) were positively correlated. Daily increment resolution was disrupted after 4 days of starvation. Evidence is discussed indicating that increments continue to be deposited on otoliths of slow-growing and starved larvae, but are too narrowly spaced for resolution by light microscopy. Feeding larvae more than once daily had no effect on increment deposition rates. For up to 38 days, increment counts from the sagitta and lapillus were equivalent, but for the first 20 days increment counts were easier from the lapillus, which was larger. After 20 days, the sagitta was larger and overall easier to read.

Aging and Growth of Larval Bay Anchovy, Anchoa mitchilli, from the Newport River Estuary, North Carolina

Bay anchovy (Anchoa mitchilli) larvae were hatched and reared in the laboratory from eggs collected near Beaufort, North Carolina. The first growth increment formed on otoliths on the fifth day after hatching when larvae were between 3.7 and 4.2 mm standard length. On the average, one otolith growth increment was formed per day thereafter in larvae up to 23 d posthatch. Age of wild larvae from the Newport River estuary in North Carolina was determined from otolith increment counts based on the assumption that increment deposition rates in nature are the same as in the laboratory. From their size and estimated age, it appears that the standard length (SL) of wild larvae in the estuary increases exponentially at about 4% d−1 during their first 1.6 months, increasing from 0.24 mm d−1 on day 12 to 1.11 mm d−1 on day 49. Bay anchovy spawned early in the season (e.g., April–May) could grow to maturity and reach a size (>40 mm SL) that would enable them to spawn during their first summer.