Otoliths

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 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.

Since the publication of " The Migrations of Fish " by Prof. Alexander Meek in 1916, a number of books have been published on this subject. However, most of these books only cover one type of migratory mechanisms. This book aims to overcome this drawback by presenting a comprehensive coverage of all life history strategies-amphidromy, diadromy, oceanodromy and potadromy in one book. The first section of this book reviews the history of fish migration studies, and the main trends and challenges of fish migration research. The second section describes the main processes and patterns associated with all migratory life history strategies, as well as the main problems associated with their conservation. The relevance of life history plasticity for migratory fishes has been highlighted in this section. Finally, the third section provides examples of the main methodologies used to study fish migration.

Une excavation temporaire dans une sablière désaffectée au Quoniam, Haravilliers (Val d'Oise), a rendu à nouveau possible l'examen des couches du Marinésien basal (Bartonien supérieur), notamment le niveau couramment dénommé horizon de Mortefontaine. Bien que précédemment étudié par MORELLET & MORELLET (1922), nos fouilles ont permis d'en préciser la stratigraphie et le contenu paléontologique. Six espèces de gastéropodes, nouvelles pour l'horizon de Mortefontaine, ont été identifiées. Des otolithes de poissons osseux, attribuables à quatre espèces différentes, sont signalés, ce qui est une première pour ce niveau. Abstract: Thanks to a temporary excavation in a disused sand quarry located in Le Quoniam, Haravilliers (Val d'Oise), it has been possible to again study deposits from the basal " Marinesian " , notably a bed commonly named Mortefontaine Member, and their contact with the Auversian. Although previously studied by MORELLET & MORELLET (1922), our digs allowed us to further investigate their stratigraphy and paleontological content. Six gastropod species have been identified, which are new for the Mortefontaine Member. Bony fish otoliths, belonging to four species, are also reported, for the first time from this level

Otoliths widely used to determine taxonomy, growth, age and population structure of fishes. This study aims to determine the relationship between otolith morphometric to fish sizes and morphological characteristic of otolith. Data were collected from April to July 2015 in Muncar, Bali Strait. The statistical tests using two tails t-test paired sample also implemented to examine differentiation between left and right otolith measurement. The linear regression and exponential equation used to examine otolith morphometric parameter to fish size. Otolith morphological characteristics presented descriptively and emphasized using 6 descriptors of shape indices. The results showed no significant differences between left and right otolith. The otolith-fish size relationship was isometric. An O L (length of otolith) found as the best indicators to estimate the original size of fish. The otolith has specific morphological characteristics, in particular sulcus acusticus, rostrum and antirostrum were similar with other species from Sardinella genus. Shape indices also provided to confirm the morphological otolith.

were found to produce otolith daily increments, as well as a consistently visible marine-entry check formed during their transition to salt water. Field-collected O. nerka post-smolts of an equivalent age also displayed visible checks; however, microchemistry estimates of marine-entry date using Sr:Ca ratios differed from visual estimates by c. 9 days suggesting that microstructural and microchemical processes occur on different time scales.

This paper is the first approach to characterization of the strategies for fish resources and their implications in the subsistence of the hunter-gatherer groups that inhabited Patagonia Northern Coast in pre-Hispanic times. Our study is focused in otolith analysis (calcium carbonate structures in the internal ear of bony fish) of whitemouth croaker (Micropogonias furnieri). Otolith morphology and morphometry in relation to present data are compared. The total length, population structure and composition of archaeological population are considered, being differences between populations. These differences in relation with the micro environmental features of each sector and possible techniques of capture of this resource are evaluated. This paper constitutes the first step to understand the selection strategies, captures and advantage of this resource.

Otolith chemistry has gained increasing attention as a tool for analyzing various aspects of fish biology, such as stock dynamics, migration patterns, hypoxia and pollution exposure, and connectivity between habitats. While these studies often assume otolith elemental concentrations reflect environmental conditions, physiological processes are increasingly recognized as a modulating and/or controlling factor. In particular, biomineralization – the complex, enzyme-regulated construction of CaCO3 crystals scaffolded by proteins – is believed to play a critical role in governing otolith chemical patterns. This review aims to summarize knowledge on otolith composition and biophysical drivers of biomineralization, present hypotheses on how biomineralization should affect element incorporation, and test the validity thereof with selected case studies. We assume that tracers of environmental history will be dominated by elements that substitute for Ca during crystal growth or that occur randomly trapped within the crystal lattice. Strontium (Sr) and barium (Ba) largely comply with the biomineralization-based hypotheses that otolith element patterns reflect environmental concentrations, without additional effects of salinity, but can be influenced by physiological processes, typically exhibiting decreasing incorporation with increasing growth. Conversely, we assume that tracers of physiology are elements under physiological control and primarily occur protein-bound in the otolith’s organic matrix. Physiological tracers are hypothesized to reflect feeding rate and/or growth, decrease with fish age, and exhibit minimal influence of environmental concentration. Candidate elements phosphorus (P), copper (Cu) and zinc (Zn) confirm these hypotheses. Magnesium (Mg) is believed to be randomly trapped in the crystal structure and hence a candidate for environmental reconstruction, but the response to all examined drivers suggest Mg to be coupled to growth. Manganese (Mn) substitutes for Ca, but is also a co-factor in matrix proteins, and therefore exhibits otolith patterns reflecting both environmental (concentration and salinity) and physiological (ontogeny and growth) histories. A consistent temperature response was not evident across studies for either environmental or physiological tracers, presumably attributable to variable relationships between temperature and fish behavior and physiology (e.g. feeding rate, reproduction). Biomineralization thus has a controlling effect on otolith element concentrations for elements that are linked with somatic growth, but not for elements that substitute for Ca in the crystal lattice. Interpretation of the ecological significance of patterns from field samples therefore need to consider the impact of the underlying biomineralization processes of the element in question as well as physiological processes regulating the availability of ions for inclusion in the growing crystal lattice. Such understanding will enhance the utility of this technique to address fisheries management questions.

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).

Detailed faunal analyses were conducted on two major subsistence resources, oysters and
marine catfish, at Rollins Shell Ring, a Late Archaic (5000 – 3000 B.P.) site on the northeast
coast of Florida. The focus of this investigation was on resource exploitation, and, specifically,
whether there was evidence that oysters from this site were over-exploited. Three units from
previous excavations at the site were selected for analysis, and represent the span of occupation
recorded for this site. Measurements were obtained from oysters to determine habitat, and, along
with shell height, were compared across time for any changes in the pattern of exploitation that
would indicate over-exploitation. Marine catfish otoliths were used to provide seasonal data for
oyster harvesting, as well as information on fish ages and harvesting of this resource.

My analysis revealed that the majority of oysters used in the construction of the main
shell ring, ringlets, and other structures at this site were harvested from the same habitat. While
there were differences in oyster habitat exploitation and shell height between samples, the
difference was attributed to the variability of oyster habitats exploited and shell height in the
earliest sample of the analysis, Test Unit 10, and in the latest sample, Test Unit 2; there was less
variability noted in oyster habitat and shell height for the middle activity period recorded at the
site, Test Unit 12c. Further results indicated a seasonal preference for exploitation of both oyster
and marine catfish in warm water temperatures, and that oyster resources did not appear to be
under stress during the period of activity recorded for the site. These data suggest that it is
unlikely that over-exploitation of oysters played a role in permanent site abandonment.

Catfish otoliths excavated from two archaeological sites in Kuwait, Sabiyah (ca. 7000 Years Before Present) and Al-Khidr, ca. 4000 YBP, were compared with those of Kuwait’s modern catfish. Otoliths from Kuwait’s four species of catfish, Netuma bilineata, N. thalassina, Plicofollis dussumieri, and P. tenuispinis were collected after recording total length and weight. Data recorded for both ancient and modern otoliths, including annual ring (age), weight, length and four otolith radii from transverse sections, were subject to discriminant analysis to differentiate among species and develop classification functions for otoliths. Comparisons of the results from the ancient and modern otoliths showed that most of the excavated otoliths (78% from Sabiyah and 100% from Al-Khidr) belong to the two presently dominate species N. bilineata and P. tenuispinis, indicating that ichthyofauna of Kuwait Bay may not have changed much in the past 7000 years.

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 loss of genetic and life history diversity has been documented across many taxonomic groups, and is considered a leading cause of increased extinction risk. Juvenile salmon leave their natal rivers at different sizes, ages and times of the year, and it is thought that this life history variation contributes to their population sustainability, and is thus central to many recovery efforts. However, in order to preserve and restore diversity in life history traits, it is necessary to first understand how environmental factors affect their expression and success. We used otolith 87Sr/86Sr in adult Chinook salmon (Oncorhynchus tshawytcha) returning to the Stanislaus River in the California Central Valley (USA) to reconstruct the sizes at which they outmigrated as juveniles in a wetter (2000) and drier (2003) year. We compared rotary screw trap-derived estimates of outmigrant timing, abundance and size with those reconstructed in the adults from the same cohort. This allowed us to estimate the relative survival and contribution of migratory phenotypes (fry, parr, smolts) to the adult spawning population under different flow regimes. Juvenile abundance and outmigration behavior varied with hydroclimatic regime, while downstream survival appeared to be driven by size- and time-selective mortality. Although fry survival is generally assumed to be negligible in this system, >20% of the adult spawners from outmigration year 2000 had outmigrated as fry. In both years, all three phenotypes contributed to the spawning population, however their relative proportions differed, reflecting greater fry contributions in the wetter year (23% vs. 10%) and greater smolt contributions in the drier year (13% vs. 44%). These data demonstrate that the expression and success of migratory phenotypes vary with hydrologic regime, emphasizing the importance of maintaining diversity in a changing climate.

The Mint Spring Formation (Oligocene) is a fossiliferous sand and clay lithologic unit of the Vicksburg Group that was deposited in a shallow-water, near-shore environment across Mississippi and Alabama. Bivalves and shark and ray teeth dominate the macrofauna, and many otoliths are also present.  The otolith assemblages from three samples taken from the Mint Spring Formation in Rankin County, Mississippi, indicate a shallow near-shore environment that deepens upsection to mid-shelf depths. The dominance of sciaenids and ophichthids in the lower most sample indicate a shallow shelf environment. Upsection, these families are not as well represented and the bregmacerotids become dominant in a more diverse fauna indicating a middle shelf environment. Other shallow to middle shelf fishes that are present include congrids, engraulids, clupeids, ariids, gobiids, phidiids,
serranids, pempherids, priacanthids, cynoglossids, pleuronectids, and synodontids. The deeper water gadid is present in the uppermost sample.  The absence of  myctophids and macrourids also indicates a neritic environment with no open oceanic influence. Most taxa found in the Mint Spring Formation are represented in the present Gulf of Mexico indicating a close affinity to the current assemblage in the Gulf.

We describe here the first fossil otoliths from
the Middle Miocene (Badenian and Sarmatian) of Belgrade,
Serbia. They were obtained from Lower Badenian
outcrops at Slanci and from upper Badenian and Sarmatian
sediments recovered from four shallow wells near the village
of Barajevo. The otoliths from the Lower Badenian of
Slanci represent fishes typical for an open marine environment,
characterized primarily by the mesopelagic
families Myctophidae and Bregmacerotidae, a faunal
composition that is also well known from other time
equivalent locations in the Central Paratethys. The upper
Badenian and Sarmatian composition of the fish fauna, in
contrast, is dominated by otoliths of the family Gobiidae,
indicating a sharp environmental shift from open marine to
shallow water, probably slightly brackish environments,
which is also confirmed by the faunal composition of
mollusks, foraminifera, and ostracods. Most of the gobiid
genera identified in the samples from Barajevo represent
small fishes of the so-called sand gobies with Ponto-Caspian
affinities, such as Economidichthys, Knipowitschia, or
Pomatoschistus, or are entirely endemic to the Ponto-
Caspian Basin, such as Hyrcanogobius. Another group of
endemic Ponto-Caspian gobies is the first fossil record
interpreted to represent the genus Proterorhinus. These and
other finds currently being investigated indicate that the
origin of the extant, rich, endemic gobiid fauna of the
Ponto-Caspian Basin dates back to a crucial time in the
development of Paratethys during the Middle Miocene
when it segregated from the Mediterranean with the onset
of phases of low salinity in the basin. In addition, we
briefly discuss the distribution of certain gobiid species
during Late Badenian and Sarmatian as it begins to emerge.
The following new taxa are described based on fossil
otoliths: Hyrcanogobius hesperis n.sp. and Proterorhinus
vasilievae n.sp.

Abstract.—Otolith chemical signatures were evaluated as natural tags to distinguish wild from hatchery produced
juvenile red snapper Lutjanus campechanus. Otoliths were sampled from 59 hatchery-reared fish and 146 wild fish collected over the continental shelf from northwest Florida to Texas. One sagitta from each fish was cleaned, dissolved in ultrapure nitric acid, and analyzed with sector field inductively coupled plasma mass spectrometry to test for differences in otolith element:Ca ratios (Ba:Ca, Li:Ca, Mg:Ca, Mn:Ca, and
Sr:Ca) between wild and hatchery fish. The second sagitta was cleaned, ground to a fine powder, and analyzed with stable isotope ratio mass spectrometry to test for differences in delta (d) values of the stable isotopes 13C and 18O. Significant differences existed in otolith chemical signatures between hatchery and wild juveniles (multivariate analysis of variance, Pillai’s trace: P , 0.001). Jackknifed classification accuracies from linear discriminant function analysis indicated that hatchery fish could be distinguished from wild fish with 100%
accuracy based on otolith chemical signatures. The most important otolith chemistry feature in distinguishing hatchery from wild fish was d13C, with the mean difference in d13C between hatchery and wild fish (!2.6%) being similar to the mean difference in d13C between hatchery feeds and the predominant food of wild juveniles (!2.8%). Overall, results suggest that otolith chemical signatures may be employed as effective natural tags for mass marking of future stockings of red snapper or other marine fishes to estimate the hatchery contribution to wild populations.

Fall-run Chinook salmon (Oncorhynchus tshawytscha) from the Sacramento–San Joaquin River system form the backbone of California's salmon fishery and are heavily subsidized through hatchery production. Identifying temporal trends in the relative contribution of hatchery-versus wild-spawned salmon is vital for assessing the status and resiliency of wild salmon populations. Here, we reconstructed the proportion of hatchery fish on natural spawning grounds in the Feather River, a major tributary to the Sacramento River, using strontium isotope (87 Sr/ 86 Sr) ratios of otoliths collected during carcass surveys from 2002 to 2010. Our results show that prior to the 2007–2008 salmon stock collapse, 55%–67% of in-river spawners were of hatchery origin; however, hatchery contributions increased drastically (89%) in 2010 following the collapse. Data from a recent hatchery marking program corroborate our results, showing that hatchery fish continued to dominate (90%) in 2011–2012. Though the rebound in abundance of salmon in the Feather River suggests recovery of the stock postcollapse, our otolith chemistry data document a persistent decline of wild spawners, likely leading to the erosion of locally adapted Feather River salmon populations. Résumé : Les saumons quinnats (Oncorhynchus tshawytscha) à migration automnale du réseau du fleuve Sacramento et de la rivière San Joaquin forment l'épine dorsale de la pêche aux saumons en Californie et sont fortement soutenus par la production en alevinières. La détermination des tendances dans le temps des apports relatifs de saumons issus d'alevinières et de saumons nés dans la nature est cruciale pour évaluer l'état et la résilience des populations de saumons sauvages. Nous avons reconstitué la proportion de poissons issus d'alevinières dans des aires de frai naturelles dans la rivière Feather, un important affluent du fleuve Sacramento, en utilisant les rapports d'isotopes de strontium (87 Sr/ 86 Sr) d'otolites prélevés durant des relevés de carcasses de 2002 à 2010. Les résultats montrent que, avant l'effondrement des stocks de saumons de 2007–2008, de 55 % à 67 % des frayeurs dans la rivière provenaient d'alevinières; toutefois, l'apport d'alevinières a connu une augmentation très marquée (89 %) en 2010 dans la foulée de l'effondrement. Les données tirées d'une campagne récente de marquage en alevinière corroborent ces résultats, démontrant que les poissons issus d'alevinières sont toujours prédominants (90 %) en 2011–2012. Si la remontée de l'abondance des saumons dans la rivière Feather semble indiquer un rétablissement du stock à la suite de l'effondrement, nos données sur la chimie des otolites documentent un déclin soutenu des géniteurs sauvages, qui mène vraisemblablement à l'érosion des populations de saumons adaptées aux conditions locales de la rivière Feather. [Traduit par la Rédaction]

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.

Connectivity is a critical property of marine populations, particularly for species with segregated juvenile and adult habitats. Knowledge of this link is fundamental in understanding population structure and dynamics. Young adults of commercially important fish species Solea solea, Solea senegalensis, Platichthys flesus, Diplodus vulgaris and Dicentrarchus labrax were sampled off the Portuguese coast in order to establish preliminary evidence of estuarine nursery origins through otolith elemental fingerprints. Concentrations of Li, Na, Mg, K, Mn, Cu, Zn, Sr, Ba and Pb in the otolith section corresponding to juvenile’s nursery life period were determined through laser ablation inductively coupled plasmamass spectrometry. Element: Ca ratios in coastal fish differed significantly amongst collection areas, except for Platichthys flesus, and were compared with the elemental fingerprints previously defined for age 0 juveniles in the main estuarine nurseries of the Portuguese coast. Identification of nursery estuarieswas achieved for four of the species. Assigned nursery origins varied amongst species and differences in the spatial scale of fish dispersal were also found. Diplodus vulgaris was not reliably assigned to any of the defined nurseries. Overall, results give evidence of the applicability of estuarine habitat tags in future assessments of estuarine nursery role. Research developments on the links between juvenile and adult habitats should contribute for the integrated management and conservation of nurseries and coastal stocks.

Determining the life history consequences for fishes living in extreme and variable environments will be vital in predicting the likely impacts of ongoing climate change on reef fish demography. Here, we compare size-at-age and maximum body size of two common reef fish species (Lutjanus ehrenbergii and Pomacanthus maculosus) between the environmentally extreme Arabian/Persian Gulf (‘Arabian Gulf’) and adjacent comparably benign Oman Sea. Additionally, we use otolith increment width profiles to investigate the influence of temperature, salinity and productivity on the individual growth rates. Individuals of both species showed smaller size-at-age and lower maximum size in the Arabian Gulf compared to conspecifics in the less extreme and less variable environment of the Oman Sea, suggesting a life-history trade-off between size and metabolic demands. Salinity was the best environmental predictor of interannual growth across species and regions, with low growth corresponding to more sa...

Skipjack tuna (Katsuwonus pelamis Linnaeus, 1758) distributed vastly along the Indian Ocean south of Java, Bali and Nusa Tenggara. It has been exploited by various fishing gear yet it always assumed to be a single stock. It was not based on scientific evidence but merely based on " a scientific assumption " , so that vulnerable to subject of overfishing. This research aims to examine the alternative tool for identifying the stock structure based on the otolith shape. Sampling location took place in four regions, namely: Binuangeun, Sadeng, Prigi and Labuhan Lombok. The otolith (sagittae) samples was collected during April, August, and September 2016. The otolith shape was reconstructed using outline analysis with discrete wavelet transformation technique. A multivariate statistic using canonical analysis of principal (CAP) and ANOVA-like permutation test were also used to determine the signification among populations. The result showed that skipjack's otolith shape was varied from one and another, especially in the rostrum. But it was not statistically different among regions (p>0.001), which means a single stock of skipjack tuna was define in the Indian Ocean (Indonesian territory of FMA 573). This study also proved that otolith shape can be useful marker tool to identify stock structure for management purposes.

Understanding catfish ecology is important because catfish constitute one of the largest fish stocks in the coastal Indo-
Pacific regions. Recent technological advances have enabled the use of biological electric sensors to understand fish
ecology, but their application requires catch and release. Fish otoliths can record ecological changes, and oxygen isotopes
and Sr/Ca ratios along the growth direction are independently used to reconstruct the migration history of the fish. Here
we report high-resolution measurements of both oxygen isotopes and Sr/Ca ratios of a modern otolith from a marine
catfish (Plicofollis tenuispinis) collected from the Gulf of Khambhat, western India. Both sets of data suggest that the
catfish migrated from an estuarine environment to the sea during its lifetime. Migration history of the catfish was estimated
with monthly resolution aided by numerical modeling. Potential applications of this analysis as an environmental
recorder for variables such as temperature and water chemistry are examined.

The relationship between the otolith and body growth of the European perch ranging in total length
from 8.7 to 25.9 cm was examined. Otolith length, height and weight were recorded for each pair of sagittae. The
relationships between otolith variables and fish somatic growth were described with a non-linear function (power
model). An analysis of covariance revealed differences in these relationships between females and males. The
measurement most strongly related to fish body length was the otolith weight, with 87.5% of the variability in females
and the otolith length, with 82.9% in males. The mean percent prediction errors were less than 8%. Therefore, the
results confirmed that otolith growth reflected somatic growth, but that differed between sexes.

Patagonian toothfish (Dissostichus eleginoides) or ‘Chilean sea bass’ support a valuable and controversial fishery, yet their life history is not well understood and longevity estimates range from ~20 to >50 years. In this study, lead–radium dating provided valid ages for juvenile to older adult groups, which were consistent with the counting of otolith growth zones in transverse otolith sections, and longevity estimates exceeding 30 years. Lead–radium dating revealed minor biases between the radiometric age and interpretation of growth zone counting for regional fishing areas monitored by two facilities, Center for Quantitative Fisheries Ecology (CQFE) and the Central Ageing Facility (CAF), using different age estimation techniques. For CQFE, under-ageing of ~3.3 years was observed for individuals with estimated ages under 20 years. For the CAF, ages were overestimated for young fish and underestimated for the oldest fish. Lead–radium dating detected underlying problems in coord...

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...

Altered river flows and fragmented habitats often simplify riverine communities and favor non-native fishes, but their influence on life-history expression and survival is less clear. Here, we quantified the expression and ultimate success of diverse salmon emigration behaviors in an anthropogenically altered California river system. We analyzed two decades of Chinook salmon monitoring data to explore the influence of regulated flows on juvenile emigration phenology, abundance, and recruitment. We then followed seven cohorts into adulthood using otolith (ear stone) chemical archives to identify patterns in time-and size-selective mortality along the migratory corridor. Suppressed winter flow cues were associated with delayed emigration timing, particularly in warm, dry years, which was also when selection against late migrants was the most extreme. Lower, less variable flows were also associated with reduced juvenile and adult production, highlighting the importance of streamflow for cohort success in these southernmost populations. While most juveniles emigrated from the natal stream as fry or smolts, the survivors were dominated by the rare few that left at intermediate sizes and times, coinciding with managed flows released before extreme summer temperatures. The consistent selection against early (small) and late (large) migrants counters prevailing ecological theory that predicts different traits to be favored under varying environmental conditions. Yet, even with this weakened portfolio , maintaining a broad distribution in migration traits still increased adult production and reduced variance. In years exhibiting large fry pulses, even marginal increases in their survival would have significantly boosted recruitment. However, management actions favoring any single phenotype could have negative evolutionary and demographic consequences, potentially reducing adaptability and population stability. To recover fish populations and support viable fisheries in a warming and increasingly unpredictable climate, coordinating flow and habitat management within and among watersheds will be critical to balance trait optimization versus diversification. K E Y W O R D S biocomplexity, dam operation, flow alteration, hydrology, juvenile salmon emigration, life-history diversity, migration phenology, otolith strontium isotopes, portfolio effect This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

Layman's version of the story behind validating the age of a 1245 lb. blue marlin.  See scientific article for details:
Andrews, A.H., R.L. Humphreys, and J.D. Sampaga. 2018. Blue marlin (Makaira nigricans) longevity estimates confirmed with bomb radiocarbon dating. Canadian Journal of Fisheries and Aquatic Science 75: 17-25 (dx.doi.org/10.1139/cjfas-2017-0031)

Otoliths are calcareous structures found in the labyrinth
membrane in the otic capsules of teleost fishes and are constituted
of three pairs: the sagittae, lapilli and asterisci. They
have long been recognized as being species specific. A comparative
morphology of the sagittae, asterisci and lapilli
among six eel species of Anguilliformes belonging to the
Family Congridae, Muraenesocidae and Muraenidae was
studied. A total of 64 specimens belonging to Bathyconger
wallacei (n = 23), Conger japonicus (n = 9), Muraenesox
cinereus (n = 10), Echidna polyzona (n = 4), Gymnothorax
eurostus (n = 4) and Gymnothorax reticularis (n = 14) were
collected from Tungkang, Chengkung, Changbin and Nanfangao,
Taiwan, during the months of January and February
2013. The three pairs of otoliths were extracted from the otic
capsules of the eels and observed by light and scanning electron
microscopy. The morphology of the sagitta showed differences
in shape among B. wallacei, C. japonicus, M. cinereus
and G. reticularis, but similar shapes between E. polyzona
and G. eurostus. While the morphology of the lapillus showed
some similarities in shape among B. wallacei and C. japonicus
and among M.cinereus, E. polyzona, G. eurostus and G. reticularis.
The results also showed that the asteriscus is capable
of conveying species specific information, with the asteriscus
of each species varying in form. The three otolith types were
the largest in C. japonicus and M. cinereus and the smallest in
E. polyzona, G. eurostus and G. reticularis. The usage of the
three pairs of otoliths allows for a more informative differentiation
between the Anguilliformes species in Taiwan.

Background: Early life history traits of the temperate eel Anguilla japonica and tropical eel Anguilla marmorata were
examined to determine the possible reason why these two species have similar spawning areas and oceanic larval
transport in the North Equatorial Current and yet are recruited to different but partly overlapping continental growth habitats in northern East Asia. To understand the segregative migration of these two sympatric eel species, their glass eels were collected from nine estuaries in the Philippines, Taiwan, Japan, and China. The age at metamorphosis from leptocephalus to glass eel (Tm), the age at estuarine arrival (Tt), the time between
metamorphosis and estuarine arrival (Tt−m), and the growth rate (Gt) of glass eels were calculated from daily growth
increments in their otoliths.

Results: Results indicated that the Gt was faster and the Tm was younger in A. marmorata than in A. japonica. On the other hand, fish length and the Tt at estuarine arrival were larger in A. japonica than in A. marmorata, indicating that elvers of A. japonica experience a longer oceanic drift than those of A. marmorata. In addition, the Tt−m also indicated that A. japonica experienced a longer coastal migration than A. marmorata.

Conclusion: This study validated that the Tm and Gt seem to play important roles in the segregative migration and latitudinal distribution of these two sympatric freshwater eel species in the northwestern Pacific.

We tested for density-dependent effects on the body size, ocean entry date, growth rate, and migration speed of juvenile sockeye salmon Oncorhynchus nerka in 2 yr with contrasting competitor densities during freshwater residence (intraspecific), as well as the first 2 mo of marine residence (intra- and interspecific). Juvenile sockeye salmon entering the marine environment during a year with high competitor densities (conspecifics and 9 other pelagic species groups) were, on average, 11% smaller and entered the ocean almost a week earlier. Differences between the high- and low-density years in entry size, but not entry date, were strongest in nursery lakes with high parental spawner abundance, consistent with density-dependent effects on freshwater growth. Mean daily growth rates of sockeye salmon during early marine residence did not vary between years after accounting for variation in ocean entry size and timing, even though the catch per unit effort of the most abundant juvenile salmon species increased more than 5-fold. However, juvenile sockeye salmon entering in the high-density year did migrate away from their ocean entry points significantly more rapidly (estimated ~40% increase in body lengths per second). Our results suggest that juvenile sockeye salmon growth during early marine residence may not be strongly limited by competition and that shifts in migration speed or spatial distribution may buffer individuals from competitive interactions.

The relationship between the otolith and body growth of the European perch ranging in total length from 8.7 to 25.9 cm was examined. Otolith length, height and weight were recorded for each pair of sagittae. The relationships between otolith variables and fish somatic growth were described with a non-linear function (power model). An analysis of covariance revealed differences in these relationships between females and males. The measurement most strongly related to fish body length was the otolith weight, with 87.5% of the variability in females and the otolith length, with 82.9% in males. The mean percent prediction errors were less than 8%. Therefore, the results confirmed that otolith growth reflected somatic growth, but that differed between sexes.

Characterizing biological factors associated with species-specific accumulation of contaminants is one of the major focuses in ecotoxicology and environmental chemistry studies. In this study, polychlorinated dibenzop- dioxins (PCDDs), dibenzofurans (PCDFs), and non- and mono-ortho-substituted polychlorinated biphenyl (PCB) congeners were analyzed in various fish species from the Tittabawassee and Saginaw Rivers (12 fish species; n=314 individuals), Michigan, USA. Due to their migratory habits, greater δ13C stable isotope values were found in walleye and white sucker among 12 fish species. Meanwhile, the δ15N values indicated that the trophic status was least in carp and greatest in largemouth bass. The greatest total concentrations of dioxins were found in fishes with the lowest trophic status (carp (n=50) followed by channel catfish (n=49)), and concentrations of ΣPCDD/Fs (20–440 pg/g ww (wet weight)), ΣPCBs (16–690 ng/g ww), and TEQs (6.8–350 pg/g ww) in carp were also greater than the least mean concentrations in other fishes. Contributions of various biological factors to the species accumulation were assessed. Body weight and lipid content were found to be the most significant factors influencing accumulation of ΣPCDD/Fs. Lipid content and trophic level seemed to be dominant factors determining accumulation of ΣPCB and TEQs, but negative correlations between trophic status and concentrations of ΣPCBs and TEQs were observed possibly due to the great concentrations in benthivorous fishes such as carp occupying lower trophic levels. These factors can be used to predict the contaminant levels of dioxins and health risks of the fishes in the river ecosystem.

Background Early life history traits of the temperate eel Anguilla japonica and tropical eel Anguilla marmorata were examined to determine the possible reason why these two species have similar spawning areas and oceanic larval transport in the North Equatorial Current and yet are recruited to different but partly overlapping continental growth habitats in northern East Asia. To understand the segregative migration of these two sympatric eel species, their glass eels were collected from nine estuaries in the Philippines, Taiwan, Japan, and China. The age at metamorphosis from leptocephalus to glass eel (T m), the age at estuarine arrival (T t), the time between metamorphosis and estuarine arrival (T t−m), and the growth rate (G t) of glass eels were calculated from daily growth increments in their otoliths. Results Results indicated that the G t was faster and the T m was younger in A. marmorata than in A. japonica. On the other hand, fish length and the T t at estuarine arrival wer...

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 (A M50) and at sex change (from female to terminal phase male, A 50) 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. A 50 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 poorly corresponded to the current minimum legal size for uhu in Hawai'i (12 in. or 30.5 cm fork length). Pooling these parrotfishes for management seems generally inappropriate, especially for the two large species. Age-based metrics are more informative than size-based metrics for these fishes.