Winter Ring Research Articles

Age validation of juvenile cod in the Western Baltic Sea

Abstract The methods routinely used to estimate fish age are often un-validated and susceptible to errors and uncertainties. Despite numerous attempts, age determination of western Baltic cod (WBC, Gadus morhua) using otoliths is still unreliable, predominantly due to inconsistent interpretation of the first translucent zone (TZ). Length-frequencies of undersized (<38 cm) cod collected during 2013–2016 from pound nets near Fehmarn Island were analysed to understand TZ formation patterns. A clear minimum separated two cohorts within the length-frequency samples every year. The length-frequency information was combined with otolith edge analysis to observe the development of TZs in age-0 and age-1 cod otoliths, and to validate the timing of TZ formation, which was consistently completed between September and December. Mean TZ diameters of 4 917 juvenile cod otoliths varied between cohorts (mean diameters of the first TZ: 2.0 ± 0.5 mm; second TZ: 3.9 mm ± 0.5) and TZ diameter variation was found to be related to individual growth rate. The timing of formation of the first TZ was positively related to water temperature, and was confirmed as a “summer ring” rather than a “winter ring”. TZ formation and shallow-water occupancy suggest an influence of peak summer water temperatures on WBC ecology. An age reading guide for juvenile WBC otoliths is provided.

Retraction: ‘Are European birds leaving traditional wintering grounds in the Mediterranean?’, by José Luis Tellería, Álvaro Ramírez and José Ignacio Aguirre

The above article, published online on 20 January 2015 in Wiley Online Library (wileyonlinelibrary.com), has been retracted by agreement between the authors, the journal Editors in Chief, Thomas Alerstam and Jan‐Åke Nilsson, the Nordic Society Oikos and John Wiley and Sons Ltd.The aim of this study was to answer the question, ‘Are European birds leaving traditional wintering grounds in the Mediterranean?’ Due to an analytical error the study only analysed EURING circumstance 20 ring records (see the EURING exchange code) which excludes birds hunted by shot and other ways, but not all hunted individuals. As a result, the effect of illegal hunting on ring recoveries was not controlled for in the analyses. This means that the data is affected by ring records from birds other than ‘alive and probably healthy and released by ringer’ (condition 8 in the EURING exchange code). The authors' intention always was to include both condition 8 and circumstance 20, but unfortunately this was not the case.When the data was reanalysed including both condition 8 and circumstance 20 recoveries, there is no longer any support for the main conclusion of the paper and the authors can only conclude that winter ring recoveries in Spain of some common passerines (robin, chiffchaff and blackcap) do not decrease.The authors apologise for this mistake and hope that the retraction will serve to prevent the spread of the unsound conclusions derived from this paper.

Has the Number of European RobinsErithacus rubeculaWintering in Spain Decreased?

This paper explores the numerical trends of winter ring recoveries of the European robin Erithacus rubecula in Spain to determine whether the number of extra-Iberian individuals has decreased in recent decades. Results show that despite the increasing numbers of ringed and controlled robins, the number of recoveries of individuals of northern origin has decreased since the 1970s. This pattern is congruent with the northwards retreat of the wintering grounds of some partially migratory bird species that may be due to global warming.

Using ring records and field surveys to predict the winter distribution of a migratory passerine

Capsule Ring records can be used to predict spatial changes in habitat suitability in wintering grounds of migratory birds as shown by a case study with the Meadow Pipit (Anthus pratensis).Aims To forecast the winter distribution of the Meadow Pipit in the Iberian Peninsula and the Maghreb (1 700 000 km2) by combining ring records and fields surveys.Methods We processed winter ring records with Maxent, a popular machine-learning technique used to predict the occurrence probability of species. We then tested whether the occurrence probabilities predicted by the model were significantly positively related to the actual abundance of the Pipit in Spain and Morocco.Results Occurrence probabilities provided by Maxent explained 6% of Pipit abundance distribution in partial least squares regression analyses. There was, in addition, a weak effect of geographical location (1.5%) and a strong effect of local vegetation (17.6%) on Pipit distribution. The occurrence probabilities were used to classify the winter range of the Meadow Pipit in sectors of high, medium and low suitability. The most suitable sector occupied 9% of the region (153 000 km2) and was restricted to warm and moist lowlands where Pipits gather in grasslands.Conclusion These results support the potential usefulness of cartographic models derived from ring records to describe the wintering range of migratory birds.

A reliable method for ageing of whiting (Merlangius merlangus ) for use in stock assessment and management

Accurate age estimation is important for stock assessment and management. The importance of reliable ageing is emphasized by the impending analytical assessment of whiting (Merlangius merlangus) in the Baltic Sea. Whiting is a top predator in the western Baltic Sea, where it is fished commercially although less extensively compared to the North Sea. Although the species is considered one of the most difficult gadoids to age, few efforts have been made to shed light on the ageing problems. The aim of the present study was to identify and validate the 1st winter ring and to examine the visibility of the subsequent winter rings. Microstructure analysis was used to confirm the 1st winter ring. Additionally, otolith growth trajectories were obtained, confirming the allometric growth as seen in many fish species. The method for ageing of whole otoliths presented in this study can be directly implemented in future ageing of whiting otoliths from the Baltic Sea – and potentially also adjacent areas where the conspecifics have similar growth rates.

Spatial Segregation within the Spawning Migration of North Eastern Atlantic Mackerel (Scomber scombrus) as Indicated by Juvenile Growth Patterns

A comparison of growth data (fish length) with latitude shows that southern juvenile mackerel attain a greater length than those originating from further north before growth ceases during their first winter. A similar significant relationship was found between the growth in the first year (derived from the otolith inner winter ring) and latitude for adult mackerel spawning between 44°N (Bay of Biscay) and 54°N (west of Ireland). These observations are consistent with spatial segregation of the spawning migration; the further north that the fish were hatched, the further north they will tend to spawn. No such relationship was found in mackerel spawning at more northerly latitudes, possibly as a consequence of increased spatial mixing in a more energetic regime with stronger currents. This study provides previously lacking support for spawning segregation behaviour among North East Atlantic mackerel – an important step towards understanding the migratory behaviour of mackerel and hence the spatiotemporal distribution dynamics around spawning time.

Severe winter rings of oak trees (Quercus robur L.) from Central European Russia

Oak trees were sampled in a flood plain forest in the valley of the Zapadnaya Dvina (Daugava) river (Tver region, Russia). Annual rings of the time period from 1826 to 2010 were studied. Anatomically distinct rings with a stripe of small-sized cells in the innermost part and narrow earlywood vessels located in three to four rows occurred in 1861, 1862, 1929, 1940, 1942, 1956 and 1979. Deviations of earlywood development were associated with the drop of winter temperature below -42°C. The percentage of severe winter ring (SWR) occurrence depends upon tree age and decreases from 75.6% in younger specimens (under 41years old at the time of the severe winter) to 27.1% in middle-aged ones (from 41 to 80years) to 3.5% in trees older than 80years. Described anatomical features can be used in the reconstruction of severe winter frequency in the past.

Size structure, age, mortality and fecundity in Viviparus viviparus (Linnaeus, 1758) (Gastropoda: Architaenioglossa: Viviparidae)

1. Life strategies of Viviparidae (Gastropoda: Caenogastropoda: Architaenioglossa) in various aquatic habitats: Viviparus viviparus (Linnaeus, 1758) and V. contectus (Millet, 1813) Beata Jakubik Folia Malacologica CrossRef

Early post-larval growth and otolith patterns in the eel Anguilla anguilla

The length, weight, development and otolith growth of glass eel and elver were examined from their first arrival in the estuary through the summer during their upstream migration into freshwater. The level of pigmentation developed significantly from November to August, while there were significant decreases in both length and weight from February to July. No relationship could be found between radius of otolith and date of sampling, pigment stage, eel length or weight in the early months of the year indicating that sea growth of the larva and otolith growth were not directly linked. From May to August, otolith growth was significantly related to the developing pigmentation and to date of sampling, but not to either length or weight of the migrating elver, suggesting that over this time period otolith growth continued independently of somatic growth. Growth outside the first winter ring of the otolith, therefore, is not equivalent to somatic growth. Back-calculation based on an assumption that there is no somatic growth in the first freshwater summer would give a more accurate estimate of the growth curve although the differences are probably not significant for eel management.

Composition of herring stocks in the Skagerrak-Kattegat and the relations of these stocks with those of the North Sea and adjacent waters

Herring stocks in spawning condition from the waters of the Skagerrak, Kattegat, North Sea, Channel, West Scotland, Orkney-Shetland and Baltic are characterized by the means (and variances) of: number of vertebrae (VS), number of keeled scales (K 2), fish length at the time of formation of the first winter ring ( l 1) and the width of the first winter ring measured along the axis of the otolith (O 1). Five stocks of spawning herring in the Skagerrak-Kattegat are defined. Four of these are spring spawners; the fifth, an autumn spawning stock, is nowadays almost extinct. With the above characteristics of herring in spawning condition as criteria, samples of immature herring from the Skagerrak-Kattegat were separated into indigenous and non-indigenous groups. Almost all herring with two winter rings on their scales (2-group herring) and older herring were spring spawners and of local origin, whereas the 1-group comprised both spring- and autumn-spawned herring. The 1-group herring caught during the International Young Fish Survey (IYFS) in February 1980 and during a trawl survey in September 1980 could be separated into the two spawning groups by their length frequency distribution. These groups displayed characteristics closely corresponding to those of indigenous (Kattegat) spring spawners, and autumn spawners from the North Sea and adjacent waters as identified by previous work. The most important herring stock recently in the fisheries is of Kattegat Spring Spawners, which were not abundant in the catches before the nineteen-seventies. A crude estimation was made of the amount of autumn-spawned herring landed by the Danish and Swedish fishing fleets from the Skagerrak-Kattegat in 1979. Of a total landing of almost 60 000 tonnes, approximately 6% could have been autumn-spawned herring.

Growth of the Otoliths of Young Herring in the Bay of Fundy

Otoliths of 217 young herring (Clupea harengus harengus L.) of lengths (total) 32-118 mm collected from Passamaquoddy Bay were examined for their development and growth. The relationship between otolith lengths (Y) and fish lengths (X) was described by a linear equation Y = −0.486 + 0.0247 X. Within the size range examined, two otolith growth stanzas were shown and expressed by the equation Y = −0.788 + 0.0296X for fish < 75 mm, and Y = 0.333 + 0.0155X for fish ranging 75-118 mm in total length. A hyaline ring around the nucleus of unknown origin, and different from the winter ring, was observed in some otoliths.

テトラサイクリン標識によるエゾバフンウニ殻板生長線の観察

The present study was undertaken, with the aid of tetracycline labelling, to know whether pigmented-growth zones in the test plate of a sea urchin, Strongylocentrotus intermedius, can be regarded as real annual zones or not. The urchins were reared in aquaria for fourteen months from August, 1967 to October, 1968, giving tetracycline four times at appropriate time intervals through the peristomial membrane. Pigmented-growth zones were clearly seen along the longitudinal suture of each of the test plates, while they were not clear along both the latitudinal areas of the suture and along the inner surface. In each test of the sea urchins labelled with tetracycline four times, only two bands of the tetracycline fluorescence were observed along both the longitudinal suture and the inner surface. A pigmented-growth zone was clearly observed in each test plate between these two bands of tetracycline fluorescence caused by the injection on October, 1967 and March, 1968. The pigmented zone was concluded to be the winter ring in each test plate during the active growth period in winter.

Number of Circuli and Time of Annulus Formation on Scales of Pink Salmon (Oncorhynchus gorbuscha)

Mean numbers of circuli on scales of juvenile pink salmon collected along the coast of North America in 1964 increased from 1.7 on June 23 to 17.4 on September 10. On scales of adults collected from the eastern North Pacific Ocean from 1962 to 1965, mean numbers of circuli ranged from 24.1 on January 23 (1964) to 46.9 on September 2 (1962). The fork length at time of scale formation was approximately 60 mm. Mean fork length increased with the total number of circuli. The relationship of fork length to number of scale circuli showed some variation between stocks. The winter ring was present or was being formed on the majority of scales taken in late January. The development of the annulus varied considerably among individual fish.

Growth Characteristics of the Poeciliid Fish Platypoecilus maculatus

ONE of the primary problems in fishery biology is that of distinguishing discrete populations of food fishes. This is frequently done by morphometric studies of local forms, and Ehrenbaum (1929) has pointed out that such studies have merely a theoretical but also ... practical importance in the interests of rational utilization of the stock. It has been suggested by Lea (1929) that characters might serve as accessory race characters. He and his associates have shown that the scale patterns in Norwegian herring, Clupea harengus Linnaeus, reflect differences in types, and also reveal place of origin and the stock to which an individual or a population belongs. Ford (1933) experimented with regression equations of the type y = a ?bx as a technique for the comparison of in length in different geographical areas. Other biologists, for example Biickmann (1938) also have discussed the application of this equation to phenomena. This technique is based on the correlation between calculated length of herring at the formation of a given winter ring (In) and the calculated length at the time the next ring is laid down (In. +). Thus , + 1= a bl,. The formula also indicates that follows a geometric progression with annual increments becoming smaller and smaller in constant ratio. Differences due to annual changes in conditions of are recognized, however, and the geometric law is regarded as the smoothing out of real fluctuations which are likely to recur year after year. Differences in between herrings of different geographical areas were expressed by Ford in a series of regression equations and calculated limiting values, or asymptotic limits of growth, which changed from south to north. These equations were derived from data on mean calculated lengths of herring from 11 to as old as 113 caught in the North Sea, the English Channel and off Iceland. The values for the slope of the regression lines varied from around 0.6 in Lowestoft herring to 0.74 for the Icelandic forms, with predicted ultimate size (y-intercept -complement of slope) similarly differing from 27.5 cms. in the south to 36.2 cms in the north. Walford (1946) described a convenient graphic method for plotting that part of the that lies beyond the inflection point of the ordinary sigmoid curve that is derived by plotting length against age. He transformed this portion of the usual curve into a straight line by plotting length at age n + 1 against length at age n. This was shown to apply commonly (but not always) to the of individuals of various types of organisms from clams to man, as well as to averages of groups of individuals in a population. Walford (op. cit.) derived two growth the same as the slope and the limiting value derived by Ford from the regression equations. These characteristics, descriptive of the of different organisms, he

マシジミの幼貝に就て

The larvae of the “Mashijimi”, a fresh water hermaphroditic shell, hatch out and grow in the branchia of mother shell up to D-shape stage; immediately after the discharge out of mother shell, the larvae enter the bottom life. The season of discharge, though varied depending on the temperature of water, was found fo fall in May and thenceforth in Gifu Prefecture, and July to September in Nagano Prefecture. The discharged larvae, collected in natural water, are rather easily raised in the laboratory at least to the first winter. The laboratory test showed the rate of growth does not much vary among the youngs collected as 4 different places in the said prefectures and also those collected in natural waters near Ueda city, Nagano Prefectme. The size attained in the end of year is about 1mm. in the length of larval shell. This size is much smaller than observed in Paphia philippinarum, Meretrix meretrix and Anadra subcrenata, all important commercial species cultured in the Japanese shallow salt water. Evidence gathered by the field obsesvation indicate that a great number of population (young) succumb in their first winter; and also that some individuals which passed the first winter do not show the first winter ring on the umbo.

カムサッカ沿岸で漁獲された白鮭の組成

With the scales taken from 13026 specimens, out of the catch in 1940, the composition of the shoals of Oncorhynchus keta (WALB.), Caught in Kamchatka was studied. Fishes were classified according to the breadth of the first and second winter rings on the scale. Age determination showed how the composition of each year class fishes varies with respect to the 4 fold categories: -A1A2, A1B2, B1B2, and B1A2, where A means narrow, B, broad winter ring, while suffix 1 means the first, 2, the second winter ring.

スケトウダラの年齢組成(豫報II)

By the same method as used in the previous report I. 1, 305 individuals were measured. Results demonstrate the following facts. 1) Female is superior to male in sex ratio, namely the former 65% and the latter 35%. 2) The maturity is nearly the same compared with the previous report. 3) Shoals are com ?? osed of the 6 age groups of 3 to 8 years old in the fishing ground of Hokkaido, and 8 age groups of 3 to 10 years old in that of Niigata. 4) A specific body length was back-calculated from the distance from the centre of a vertebra to the first winter ring which is formed on the surface of vertebra, as shown in figure. 1. Following results are obtained. Prin ?? pal mode shows 9•1-9•5cm in Hokkaido Pref. and 8•6 ?? 9•0cm in Niigata Pref., hence, the author considers that the stocks in both fishing grounds are not of a single origin.

Notes on the Biology of Certain Lamellibranchs on the Scottish Coast

1. The observations were made on the Hunterston Sands, Ayrshire, opposite the Cumbrae.2. Small cockles appear on the ground about the beginning of August. This points to the breeding season being in summer and not spring, as is usually stated.3. By the end of the first autumn some few of the spat are as much as 10 mm. in length, but most are under 6 mm. The winter ring is faint and easily overlooked.4. The first of the several well-defined rings is therefore not the first but the second winter ring.

The Reproductive Organs of the Herring in Relation to Growth

SUMMARYFrom two series of samples of different populations of herrings from the neighbourhood of the Isle of Man, data were obtained of the lengths, weights, gonad-weights, and ages of 396 mature fishes. The growths of the whole body and of the gonads were represented by the upper portions of S-shaped curves. The male and female body-weights are nearly the same at any age over the range considered, but the testes of the male are always heavier than the ovaries of the female in such comparable fishes. The females attain a greater size than the males.The weight of the gonads bears a linear relationship (as a first approximation) to the total weight of the fish over the range of size considered. The regression functions evaluated for the two sexes arewhere y is the gonad-weight and x the total weight of the fish, both in grams. The difference between the weights of testes and ovaries in male and female fishes of the same size is therefore about 4·7 gm., which is shown to be significant. It cannot be due to specific gravity of growthrate differences, since the regression coefficient (0·26) is the same for both sexes.It is suggested that the reproductive organs start to develop in the summer following the laying down of the first winter ring on the scales; and that the initial handicap in female gonad-weight may be due to the males being smaller than the females at this time.Confirmation of the conclusions drawn from the Calf herring is given by a similar analysis of the Low herring samples.