Growth Increments In Otoliths Research Articles

Arctic cod (Boreogadus saida) hatching season and growth rates in the Bering, Chukchi and Beaufort seas

Arctic cod is an important prey species in Arctic marine ecosystems that provides efficient energy transfer from producers to consumers in the food web. Arctic cod are locally abundant throughout the Arctic, though little is known about their early life stages in the Pacific Arctic, especially when and where they spawn and hatch. This study estimated hatch dates and growth rates of first year Arctic cod through analysis of otolith growth increments. First-year Arctic cod were captured in the northern Bering, Chukchi, and Beaufort seas during the spring or summer between 2012 and 2017. Estimated hatch dates ranged widely from November to June with peak hatching occurring from February through May, depending on the region of capture. Combined with large individual and regional variability in growth rates, this suggests a bet-hedging strategy to ensure some larvae encounter favorable growth conditions. In addition to regional differences, we identified a clear separation of hatch dates between spring- and summer-caught Arctic cod in the Chukchi Sea, suggesting different origins or strong size-dependent mortality. Finally, differences in hatch dates between pelagic and demersal juveniles indicate that older, larger juveniles begin to settle to the seafloor on deeper portions of the shelf in late summer. The results of this study set a benchmark for Arctic cod early life history in these regions and provide context for monitoring early life stages in a changing environment.

Characteristics of early Atlantic cod (Gadus morhua L.) catches based on otoliths recovered from archaeological excavations at medieval to early modern sites in northern Norway

Abstract We compared stock origin, size- and age-distributions, and length growth rates derived from Atlantic cod otoliths from archaeological excavations at two sites in northern Norway: Vágar in Lofoten (68°12′N, ad 1156–1285) and the Værbukta site (70°57′N, ad 1450–1680). For comparison, modern otoliths were sampled during 1993–2001 from areas situated close to Vágar and Værbukta. Length-at-age from pre-20th century samples was back-calculated from otolith growth increments. The pre-20th century cod from Vágar was dominated by northeast Arctic cod (NEAC) of age 9–16 years and were much older and larger than the pre-20th century cod from Værbukta, which were dominated by coastal cod of age 2–6 years. Cod from Vágar had smaller increments and a shorter back-calculated length-at-age than modern cod from Lofoten. In contrast, the predominantly coastal cod from Værbukta had similar increments width and length-at-age as in modern samples. Age-distributions and mortality rates of the pre-20th century Vágar cod and NEAC from Lofoten in the 1930s were similar, indicating that both age at maturity and longevity were similar for these time periods. This contrasts with truncated and young age-distributions of spawning NEAC in the 1980s and 1990s following the strong increase in fishing and total mortality rate in the period 1955–2000.

Habitat type and environmental conditions influence the age and growth of a temperate marine damselfish

Life history parameters for fishes have generally been applied to species across their entire range, however, different ecological and environmental conditions and processes (e.g., sea surface temperature, habitat, primary productivity, fishing mortality, resource availability) influence life history patterns at smaller spatial scales. By focusing on a historically protected species, we determined how environmental and ecological factors shape patterns in growth and longevity, without the impact of fishing. The Garibaldi (Hypsypops rubicundus) is a territorial marine damselfish native to the shallow rocky reefs of southern California. Garibaldi were collected from five mainland locations and five Channel Islands throughout the Southern California Bight. Paired natural reef and artificial reef habitats (i.e., breakwaters and jetties) in each mainland location were sampled. Otolith-based ageing and biological data from these populations were used to assess how age and growth vary by location, reef type (natural/artificial), island or mainland, mean annual sea surface temperature, and/or sex. The annual formation of growth increments in otoliths was validated in-situ using tetracycline mark-recapture methods to confirm that increments are formed annually. Garibaldi grew significantly larger on artificial reefs than on natural reefs but tended to live longer on paired natural reefs. Regionally, growth and longevity followed mean annual sea surface temperature gradients, consistent with Bergmann’s rule. Garibaldi exhibited clear sexual size dimorphism; males grew larger, which is uncharacteristic for both damselfish and other marine fishes from the southern California. The Garibaldi collected for this study had a maximum age of 57 years, which makes this the longest lived damselfish species by two decades.

Abundance and Growth of the European Eels (Anguilla anguilla Linnaeus, 1758) in Small Estuarine Habitats from the Eastern English Channel

Abundance and growth of the European eel from six small northern French estuaries during their growth phase were examined to explore variations according to the local habitat characteristics. The length–weight relationships and growth models fitted to length-at-age back-calculated otolith growth increments were used to compare the growth. Higher abundances were observed in the smaller estuaries (2.4 to 10.5 ind. fyke nets 24 h−1). The eel length ranged from 215–924 mm with an age range of 4–21 years. There was no significant difference in fish eel lengths or age except in the Liane estuary where the individuals were larger. The length–weight relationships showed an isometric or positive allometric growth in most estuaries. The Gompertz growth models, which best fits the growth, showed no significant differences between estuaries except for female eels from the Liane and the Somme estuaries where the growth performance index was higher. The estimated annual growth rate varied from 2.7 to 115.0 mm·yr−1 for female and from 4.4 to 90.5 mm·yr−1 for male. The present study shows that eels in the six estuaries had CPUE and growth rates similar to those previously reported in larger habitats. These results reinforce the idea that small estuaries are important habitats that contribute significantly to the eel population and, therefore, play an essential role in conservation strategies for European eel.

First record and otolith morphometric description of an adult lightfish, Ichthyococcus ovatus (Actinopterygii: Stomiiformes: Phosichthyidae), caught in the Strait of Sicily (central Mediterranean Sea)

On July 2018, one specimen of Ichthyococcus ovatus (Cocco, 1838) was caught in the Strait of Sicily during the International Bottom Trawl Survey in the Mediterranean (MEDITS). The adult I. ovatus measured 49 mm in total length and weighed 1.44 g. In this context, the presently reported study constitutes the first and deepest record of an adult of I. ovatus as well as the morphometric description of its sagittal otoliths. In addition, we provide an age estimation as well as an update of the geographical distribution of this bathypelagic species around the Mediterranean Sea. Based on the growth increments of sagittal otoliths, the estimated age was five years. Specifically, the otolith from the presently reported specimen of I. ovatus tended to be elliptic in shape related to aspect ratio and high rectangularity while circularity showed high complexity of otolith contour complexity. The absence of economic value of rarely reported species may underestimate their abundance. Therefore, more studies and research surveys would be necessary to fill the information gap on the biology of these deep-water species.

Age and growth of Antarctic deep-sea smelt (Bathylagus antarcticus), an important mesopelagic fish in the Southern Ocean

As one of the most abundant mesopelagic fishes, the Antarctic deep-sea smelt Bathylagus antarcticus plays an important role in the Southern Ocean ecosystem. However, because of a lack of studies on this species, there are major gaps in our knowledge of its life history such as age and growth pattern. Fish were collected from the Ross and Amundsen seas in the southern part of the Pacific sector, and from the Cosmonaut Sea in the southwestern part of the Indian sector, in austral summer of 2020. Age determination was made from an analysis of otoliths, and growth curves were estimated through mixed-effects models based on back-calculated length-at-age data. Bathylagus antarcticus shows a positive allometric relationship between total length and wet weight; the results indicate that it can live to age 17 years; and the von Bertalanffy growth function was estimated on the population level with L∞ = 143.83 mm, K = 0.14 year−1, and t0 = −0.64 year. Fish in the Ross and Amundsen seas showed larger mean asymptotic length than that fish in the Cosmonaut Sea, and the K values and otolith growth increments in the first 6 years differed between regions. This work is the first to estimate the age and growth of B. antarcticus, and forms an important basis of forthcoming studies on population dynamics and ecosystems in the Southern Ocean. The long lifespan and slow growth of this species make it a potentially suitable environmental indicator, to be investigated through tools like otolith microchemistry analysis.

Estimating age and growth of roosterfish (Nematistius pectoralis) from otoliths

The roosterfish is a coastal pelagic species that inhabits shallow waters of the Eastern Pacific Ocean. Despite its ecological and economic importance within the region, there are few studies on its basic biology, especially those focused on age and individual growth. Therefore, the objective of this study was to estimate roosterfish age and individual growth parameters through counting growth increments of sagittal otoliths. The work focused on organisms caught off Baja California Sur, Mexico (BCS) by both the sport and artisanal fishing fleets from 2010–2017. A total of 266 organisms were sampled during the study period, ranging in size from 5.2–133 cm fork length. A model was generated to describe the relationship between otolith radius (OR) and fork length (FL) of the fish, where FL = -43.3 + 44.59 OR. The periodicity of otolith growth increment formation was annual, and this study found roosterfish age estimates to range from 0 to 8 years old, with most individuals ranging from 1–2 years of age. Based on the fitting of the data to three individual growth models (Gompertz, Logistic and von Bertalanffy, VBGF), the VBGF best fit the individual growth curve for roosterfish. The VBGF parameter of L∞ = 131.53, k = 0.35 y t0 = -0.23 supports previous studies and suggests that roosterfish are very fast growing in the first years of life.

Differences in metabolic rate between two Atlantic cod (Gadus morhua) populations estimated with carbon isotopic composition in otoliths.

The isotopic composition of inorganic carbon in otoliths (δ13Coto) can be a useful tracer of metabolic rates and a method to study ecophysiology in wild fish. We evaluated environmental and physiological sources of δ13Coto variation in Icelandic and Northeast Arctic (NEA) cod (Gadus morhua) over the years 1914–2013. Individual annual growth increments of otoliths formed at age 3 and 8 were micromilled and measured by isotope-ratio mass spectrometry. Simultaneously, all annual increment widths of the otoliths were measured providing a proxy of fish somatic growth. We hypothesized that changes in the physiological state of the organism, reflected by the isotopic composition of otoliths, can affect the growth rate. Using univariate and multivariate mixed-effects models we estimated conditional correlations between carbon isotopic composition and growth of fish at different levels (within individuals, between individuals, and between years), controlling for intrinsic and extrinsic effects on both otolith measurements. δ13Coto was correlated with growth within individuals and between years, which was attributed to the intrinsic effects (fish age or total length). There was no significant correlation between δ13Coto and growth between individuals, which suggests that caution is needed when interpreting δ13Coto signals. We found a significant decrease in δ13Coto through the century which was explained by the oceanic Suess effect-admixture of isotopically light carbon from fossil fuel. We calculated the proportion of the respired carbon in otolith carbonate (Cresp) using carbon isotopic composition in diet and dissolved inorganic carbon of the seawater. This approach allowed us to correct the values for each stock in relation to these two environmental baselines. Cresp was on average 0.275 and 0.295 in Icelandic and NEA stock, respectively. Our results provide an insight into the physiological basis for differences in growth characteristics between these two cod stocks, and how that may vary over time.

Lifelong divergence of growth patterns in Arctic charr life history strategies: implications for sustainable fisheries in a changing climate

Arctic charr (Salvelinus alpinus Linnaeus, 1758) are phenotypically variable with multiple life history strategies including anadromous and freshwater resident individuals. The mechanism determining life history is believed to be set early in life. Anadromous individuals show greater seasonality in growth and feeding after the first seaward migration relative to resident conspecifics. We used otolith growth increment measurements to estimate lifelong growth patterns for 355 individuals with anadromous or resident life history from four populations within Cumberland Sound, Nunavut. Using a general and a generalized linear model, we discovered a linear increase (estimate = 0.006) in growth for both Arctic charr life histories between 1990 and 2016. Resident Arctic charr have lower annual growth (estimate = −0.176) and show a decrease in the annual proportion of summer growth as they age (estimate = −0.042), whereas their anadromous counterparts maintain a higher seasonality in their growth patterns with age. This suggests that growth is indeed important in life history trajectory for Arctic charr and that seasonal growth patterns differ among life histories. The results highlight the importance of improving our understanding of mechanisms influencing life history trajectory in Arctic charr to ensure sustainability of harvested Arctic charr populations in a changing climate.

Fish and Sclerochronology Research in the Mediterranean: Challenges and Opportunities for Reconstructing Environmental Changes

Over the past two decades, the field of sclerochronology has been rapidly developing, with scientists devoting significant efforts to studying the physical and chemical variations in hard tissues of aquatic organisms. Most of this research has been limited to certain taxa and geographic areas. Although growth increments in fish otoliths are used for sclerochronology purposes, relatively little has been done in the Mediterranean Sea. According to the literature, the chemical composition of otoliths from Mediterranean fish species has primarily been used for analysing migration patterns, habitat use and population structure of commercially important fish species. To the best of our knowledge, there are no studies on fish growth chronology construction conducted in the Mediterranean Sea. In order to identify the opportunities for sclerochronology research on fish from the Mediterranean, we used FishBase to identify potential candidate species with a sufficiently long-life span and clearly defined growth increments for growth chronology construction and otolith chemistry research. We also present the challenges and limitations for sclerochronology research, including: (i) very few fish species in the Mediterranean Sea have a longevity of several decades, (ii) issues associated with reliable age determination for certain long-lived fish species, (iii) a general lack of understanding and effort to constructed and manage otolith collections, and (iv) limitations imposed by the availability of funding, expertise and instrumentation. Despite these challenges, fish sclerochronology research has strong potential in the Mediterranean and adjacent seas. Recent studies in the Adriatic Sea have resulted in the construction of bivalve chronologies and the geochemical analysis of shells, providing important time-series data for comparative analysis and a multispecies approach. Furthermore, studies conducted in other parts of the world have demonstrated great potential for the use of fish otoliths in monitoring environmental variability and the effects of pollutants and disturbance.

Reproductive life-history strategies in a species-rich assemblage of Amazonian electric fishes.

The reproductive biology of only a small fraction of Neotropical freshwater fishes has been described, and detailed comparative studies of reproductive life-history variation in the Neotropical ichthyofauna are lacking. Here we describe interspecific variation in reproductive life history for a multi-species assemblage of the electric knifefish genus Brachyhypopomus (Hypopomidae: Gymnotiformes: Ostariophysi) from Amazonian floodplain and terra firme stream systems. During a year-round quantitative sampling program, we collected and measured key life-history traits from 3,410 individuals. Based on oocyte size distributions, and on circannual variation in gonadosomatic indices, hepatosomatic indices, and capture-per-unit-effort abundance of reproductive adults, we concluded that all species exhibit a single protracted annual breeding season during which females spawn fractionally. We found small clusters of post-larval individuals in one floodplain species and one terra firme stream species, but no signs of parental care. From analyses of body size-frequency distributions and otolith growth increments, we concluded that five species in our study area have approximately one-year (annual) semelparous life history with a single reproductive period followed by death, while two species have a two-year iteroparous life history, with breeding in both year-groups. Despite predictions from life-history theory we found no salient correlations between life history strategy (semelparity or iteroparity) and habitat occupancy (floodplain or terra firme stream). In the iteroparous species B. beebei, we documented evidence for reproductive restraint in the first breeding season relative to the second breeding season and argue that this is consistent with age-regulated terminal investment.

Hatching Time and Early Growth of Diplodus sargus sargus Inhabiting a Coastal Area of Gökçeada Island, Turkey

Daily growth increments in sagittal otoliths were used to estimate the age and growth of young of the year (YOY) white seabream, Diplodus sargus sargus collected between June 2013 and June 2014 at 6 different locations in the shallow waters (<20 m) off Gokceada, Turkey. Estimated ages from otolith daily growth increments (DGI) were found 42–238 days old. The mean daily growth rate of YOY D. sargus sargus was estimated as 0.046 cm/day. ANCOVA indicated that there was significant difference in daily growth rates between the locations (F = 22.92, df = 5, P < 0.001). The maximum daily growth rate of 0.055 cm/day was found in the location 2, while the minimum value of 0.037 cm/day was observed in the location 4. Hatching time was determined by subtracting the daily age of the fish from the sampling date and then hatch date frequency distributions were determined to occur from January through June, and 2 main hatching peaks were observed from the different locations. Linear relationships between otolith morphology (otolith length; OL, width; OW and radius; OR) and fish length (TL) were obtained.

Fishing in hot waters threatens phenotypic diversity.

In Focus: Morrongiello, J. R., Sweetman, P. C., & Thresher, R. E. (2019). Fishing constrains phenotypic responses of marine fish to climate variability. Journal of Animal Ecology, 88, 1645-1656. Forces of unnatural selection, such as climate change and harvest, are rarely studied in concert, yet hold thegreat potential to act synergistically on individual performance, susceptibility to harvest, tolerance to warming temperatures, and ultimately population persistence and resilience. In this paper, Morrongiello etal. (2019) used long-term monitoring of a site-attached temperate reef fish, the purple wrasse (Notolabrus fucicola), to test novel predictions about how fisheries management and climate variability could alter individual growth rates and thermal reaction norms within and across stocks. Otolith growth increments were collected from three south-east Australian populations between 1980 and 1999, pre- and post-harvest, throughout an intensive warming spell. Using hierarchical models to partition variation in growth within and between individuals and populations, Morrongiello etal. detected increased average growth rate with warming, a release from density dependence post-harvest, and a fishing-by-warming interaction that decreased diversity in thermal growth reaction norms because large individuals that tend to better tolerate warm temperatures were effectively culled from the population. This study outlines the importance of determining which phenotypes are more resilient to increasing temperatures, how fisheries should manage for them, and how such collective knowledge could help preserve and even promote resilience of managed populations to increasing temperatures in ecosystems threatened by climate change.

The visual quality of annual growth increments in fish otoliths increases with latitude

This study evaluated the latitudinal influence on otolith readability through average percent error (APE) assessments and contrast ratios evaluations of the opaque and translucent incremental zones in Micropogonias furnieri otoliths (n = 83) sampled along the Southwestern Atlantic Ocean. Otolith images show well-structured increments in high latitudes. Contrast ratios increased and APE decreased significantly with latitude, respectively, therefore suggesting that M. furnieri otolith visual quality and growth increment readability increase with latitude.

Daily growth increments in otoliths of wild-caught honmoroko Gnathopogon caerulescens.

Otolith growth increments in wild-caught alizarin complex one (ALC)-marked honmoroko Gnathopogon caerulescens were examined to verify the veracity of the age determination method in cyprinids. ALC-marked G. caerulescens recaptured from their natural environment had lapilli increment counts outside the ALC ring mark that had formed on a daily basis during the juvenile stage. This apparently being the first direct evidence of daily periodicity of otolith increment formation in wild-caught cyprinids.

Characteristics of two populations of Thai river sprat Clupeichthys aesarnensis from man-made reservoirs in Thailand and Laos, with aspects of gonad development

Growth and reproduction of the Thai river sprat Clupeichthys aesarnensis (Teleostei: Clupeidae) in Sirindhorn Reservoir, Thailand, and Nam Ngum Reservoir, Laos, were investigated using age estimates obtained from daily growth increments in otoliths and gonad observations. This species breeds throughout the year in both reservoirs, although water temperature was higher in Sirindhorn than in Nam Ngum. The Sirindhorn population tended to mature at smaller size (length) and younger age than the Nam Ngum population; the Sirindhorn population also tended to grow faster before reaching sexual maturity, growing slowly afterwards, than did the Nam Ngum population. Additionally, the maximum size in the Sirindhorn population was observed to be smaller than that of the Nam Ngum population. These observations indicated that higher water temperature resulted in earlier maturation and smaller maximum size in C. aesarnensis. Meanwhile, the smaller maximum size observed in the Sirindhorn population was possibly caused by an evolutionary down-sizing resulting from the overexploitation of this population, because Sirindhorn reservoir is exposed to more intensive fishing pressure.

Irregular growth patterns in the otoliths of a short-lived forage fish do not reliably indicate reproductive history

Irregular growth patterns in fish otoliths are considered to reflect the energetic demands associated with reproduction and hence have been referred to as spawning zones or spawning checks. Here we evaluated the reliability of these checks for identifying the past reproductive history of capelin Mallotus villosus, a small pelagic fish found throughout the Northwest Atlantic that typically experiences high mortality associated with spawning. Ovarian histology was used to definitively identify females that had previously spawned via the presence of residual oocytes. Only half of the individuals confirmed to be recovering from a previous spawning episode were identified as having spawning checks in their otoliths, indicating that not all spawning episodes result in the formation of spawning checks. In addition, some individuals that appeared to be immature also had spawning checks, suggesting that processes other than spawning may be implicated in the creation of these otolith growth patterns. Analyses of otolith growth increments for fish of known reproductive status indicated that higher growth during the first primary growth season may allow capelin to reach sexual maturity at a younger age. These results strongly suggest that otolith checks are unreliable indicators of repeat spawning in capelin and may be of questionable utility for identifying past reproductive history of fishes in general. It is recommended that future research to quantify iteroparity in capelin be based on reproductive histology rather than otolith-based methods.

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.

Estimation of age and growth of juvenile angler Lophius piscatorius in the Bay of Biscay from otolith microstructure analysis

The early life history of the angler Lophius piscatorius in the Bay of Biscay was investigated by growth increments in the lapillar otoliths, this being the first time this type of analysis was conducted for this species among specimens of the Iberian stock (ICES Divisions 8.c, 9.a). Lapilli of 34 juvenile fish collected during autumn bottom trawl surveys, were successfully aged between 113 and 198 days (116–213 mm fish length). Morphology and ultrastructure analyses of the otolith’s check marks enabled us to determine the period of endogenous feeding (which according to these estimations would last between 9 and 19 days after hatching), as well as the settlement check, which indicated a relatively long pelagic phase (ca. 91 days). Hatch date was back-calculated from the date of capture indicating a spawning period from April to June, in agreement with that estimated for this population. The age–length relationship was described by the linear function LT=7.30 + 0.98 age (days) and showed an average growth rate of 0.98 mm day−1. Our results present a faster growth pattern of 0+ juveniles L. piscatorius in the Bay of Biscay than previously estimated by annual growth studies, showing that juveniles of up to 213 mm length collected in October were hatched in the same year and belonged to age class 0. These results are relevant to the knowledge of the early life history of this species and are in agreement with those obtained in the only previous microstructural study of L. piscatorius in Atlantic waters. The implications of these findings on the annual age estimation protocol based on illicia are discussed.

Intrinsic and environmental drivers of growth in an Alaskan rockfish: an otolith biochronology approach

Otolith growth-increment chronologies provide an approach for evaluating the impacts of both high-frequency (e.g., interannual) and low-frequency (e.g., interdecadal) climate variability on fish growth. A growth-increment biochronology spanning six decades, spanning several warm and cold climate regime periods, was developed for a commercially important species of rockfish, Sebastes polyspinis, in the Gulf of Alaska. To confirm that all increments were correctly identified and placed in time, we borrowed the technique of crossdating from the tree-ring science of dendrochronology, which ensured high data quality. We then used a mixed effects model to partition variance in otolith growth-increment width among intrinsic (e.g., age-related) and extrinsic (e.g., climate-related) factors. This biochronology was contrasted with one recently developed for S. alutus, a closely-related species which exhibited a significant change in growth following the late 1970s North Pacific climate regime shift. Both species generally showed positive relationships between warm climate conditions and growth, though S. polyspinis experienced a relatively smaller step-increase in growth following the regime shift. The new S. polyspinis otolith biochronology represents a long-term record of growth that extends well before biological specimens were first collected in the Gulf of Alaska, providing a potential tool for fisheries managers to evaluate the effects of climate variability on growth and biological reference points.