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Otoliths and Their Applications in Fishery Science
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Otoliths and Their Applications in Fishery Science

A special issue of Fishes (ISSN 2410-3888). This special issue belongs to the section "Biology and Ecology".

Deadline for manuscript submissions: closed (20 July 2022) | Viewed by 53467

Printed Edition Available!
A printed edition of this Special Issue is available here.

Special Issue Editor

Dr. Josipa Ferri

E-Mail Website
Guest Editor
Department of Marine Studies, University of Split, Split, Croatia
Interests: fisheries; marine biology; ichthyology; fish age and growth; fish diet
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Otoliths are the most useful and important biological structures for fishery scientists and managers around the world, primarily because they grow throughout the life of a fish, have species-specific shape, and are natural data loggers that record various data in their microstructure. These data can be used to determine the age and growth of individual fish; to study habitat interactions, migration patterns, or habitats that the fish live in; to detect water temperatures or the presence of certain pollutants in the environment; to reveal all other vital information about the life history of the fish. By determining and studying this information that is sometimes challenging to observe directly from the fish, otoliths can effectively contribute to fisheries management, assessments of ecological dynamics in marine and freshwater systems, and protection of species around the world. However, there is always a challenge to develop the appropriate technologies to extract all these data from otoliths and interpret them accurately, so I am pleased to invite you to contribute to the Special Issue “Otoliths and Their Applications in Fishery Science” in the Fishes journal.

Dr. Josipa Ferri
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Fishes is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • fish
  • otoliths
  • otolith morphology/morphometry/shape indices
  • otolith chemistry
  • fish aging
  • fish age prediction
  • identification and separation of species/populations/stocks
  • determination of fish prey identity
  • otolith atlases
  • fisheries management

Published Papers (19 papers)

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Editorial

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3 pages, 198 KiB  
Editorial
Otoliths and Their Applications in Fishery Science
by Josipa Ferri
Fishes 2023, 8(1), 35; https://doi.org/10.3390/fishes8010035 - 03 Jan 2023
Viewed by 1362
Abstract
Otoliths are one of the most useful and important biological structures for the various studies of fish, leading to many practical applications that are not limited only to ichthyology [...] Full article
(This article belongs to the Special Issue Otoliths and Their Applications in Fishery Science)

Research

Jump to: Editorial

22 pages, 5214 KiB  
Article
Length–Weight Relationships, Growth Models of Two Croakers (Pennahia macrocephalus and Atrobucca nibe) off Taiwan and Growth Performance Indices of Related Species
by Shu-Chiang Huang, Shui-Kai Chang, Chi-Chang Lai, Tzu-Lun Yuan, Jinn-Shing Weng and Jia-Sin He
Fishes 2022, 7(5), 281; https://doi.org/10.3390/fishes7050281 - 11 Oct 2022
Cited by 2 | Viewed by 2395
Abstract
Information on age and growth is essential to modern stock assessment and the development of management plans for fish resources. To provide quality otolith-based estimates of growth parameters, this study performed five types of analyses on the two important croakers that were under [...] Read more.
Information on age and growth is essential to modern stock assessment and the development of management plans for fish resources. To provide quality otolith-based estimates of growth parameters, this study performed five types of analyses on the two important croakers that were under high fishing pressure in southwestern Taiwan: Pennahia macrocephalus (big-head pennah croaker) and Atrobucca nibe (blackmouth croaker): (1) Estimation of length–weight relationships (LWR) with discussion on the differences with previous studies; (2) validation of the periodicity of ring formation using edge analysis; (3) examination of three age determination methods (integral, quartile and back-calculation methods) and selection of the most appropriate one using a k-fold cross-validation simulation; (4) determination of the representative growth models from four candidate models using a multimodel inference approach; and, (5) compilation of growth parameters for all Pennahia and Atrobucca species published globally for reviewing the clusters of estimates using auximetric plots of logged growth parameters. The study observed that features of samples affected the LWR estimates. Edge analysis supported the growth rings were formed annually, and the cross-validation study supported the quartile method (age was determined as the number of opaque bands on otolith plus the quartile of the width of the marginal translucent band) provided more appropriate estimates of age. The multimodel inference approach suggested the von Bertalanffy growth model as the optimal model for P. macrocephalus and logistic growth model for A. nibe, with asymptotic lengths and relative growth rates of 18.0 cm TL and 0.789 year−1 and 55.21 cm, 0.374 year−1, respectively. Auximetric plots of global estimates showed a downward trend with clusters by species. Growth rates of the two species were higher than in previous studies using the same aging structure (otolith) and from similar locations conducted a decade ago, suggesting a possible effect of increased fishing pressure and the need to establish a management framework. This study adds updated information to the global literature and provides an overview of growth parameters for the two important croakers. Full article
(This article belongs to the Special Issue Otoliths and Their Applications in Fishery Science)
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14 pages, 2810 KiB  
Article
Timing of Increment Formation in Atlantic Bluefin Tuna (Thunnus thynnus) Otoliths
by Enrique Rodriguez-Marin, Dheeraj Busawon, Patricia L. Luque, Isabel Castillo, Nathan Stewart, Kyne Krusic-Golub, Aida Parejo and Alex Hanke
Fishes 2022, 7(5), 227; https://doi.org/10.3390/fishes7050227 - 31 Aug 2022
Cited by 1 | Viewed by 1564
Abstract
Controversies remain regarding the periodicity, or seasonality, of otolith growth band formation, which directly influences a correct age determination of Atlantic bluefin tuna using this structure. The aim of this work was to apply marginal increment analysis and marginal edge analysis to determine [...] Read more.
Controversies remain regarding the periodicity, or seasonality, of otolith growth band formation, which directly influences a correct age determination of Atlantic bluefin tuna using this structure. The aim of this work was to apply marginal increment analysis and marginal edge analysis to determine the timing of band deposition. The index of completion was analyzed using general additive models to evaluate the importance of variables, such as month, age/size, and reader. Results indicate that the opaque band formation begins in June and is completed by the end of November. From the end of the year to the beginning of the following year, there is minimal marginal edge growth as the translucent band begins to form. The translucent zone then reaches a maximum development in May. The results obtained in this study provide evidence that the annulus formation in the otoliths of Atlantic bluefin tuna are completed later in the calendar year than previously thought. This would mean it is necessary to delay the date of the current July 1st adjustment criterion to November 30. Full article
(This article belongs to the Special Issue Otoliths and Their Applications in Fishery Science)
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18 pages, 3064 KiB  
Article
Abundance and Growth of the European Eels (Anguilla anguilla Linnaeus, 1758) in Small Estuarine Habitats from the Eastern English Channel
by Jérémy Denis, Kélig Mahé and Rachid Amara
Fishes 2022, 7(5), 213; https://doi.org/10.3390/fishes7050213 - 23 Aug 2022
Cited by 6 | Viewed by 2530
Abstract
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 [...] Read more.
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. Full article
(This article belongs to the Special Issue Otoliths and Their Applications in Fishery Science)
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13 pages, 3087 KiB  
Article
The Use of Daily Growth to Analyze Individual Spawning Dynamics in an Asynchronous Population: The Case of the European Hake from the Southern Stock
by Cristina García-Fernández, Rosario Domínguez-Petit and Fran Saborido-Rey
Fishes 2022, 7(4), 208; https://doi.org/10.3390/fishes7040208 - 18 Aug 2022
Cited by 3 | Viewed by 1656
Abstract
Daily growth patterns and their relationship with reproduction was analyzed in the European hake from the Galician Shelf, where it shows a very protracted spawning with three spawning peaks. The daily growth analysis was performed in otoliths of adult females on the transversal [...] Read more.
Daily growth patterns and their relationship with reproduction was analyzed in the European hake from the Galician Shelf, where it shows a very protracted spawning with three spawning peaks. The daily growth analysis was performed in otoliths of adult females on the transversal section of the sagittae otolith. Daily increments were measured from the border to the nucleus in females until they were discernible. Results show that daily growth of females decreases during the spawning period because they allocate less energy to somatic growth in favor of the production of gametes, with an increase in growth in July. Lastly, daily growth individual trends showed a “spawning pattern” in 28% of medium and large females, suggesting an individual spawning period of one to two months, with 4–5 valleys of narrow daily increments, likely associated to batch release: individual spawning frequency would be 4–5 days. This is the first time that individual spawning frequency in hake is estimated based on individual data. Finally, the spawning pattern is detected only once per year, indicating that a single female participates only in one spawning peak per year, supporting the hypothesis of the existence of two or more spawning components in the stock. Full article
(This article belongs to the Special Issue Otoliths and Their Applications in Fishery Science)
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15 pages, 2442 KiB  
Article
Unravelling Stock Spatial Structure of Silverside Odontesthes argentinensis (Valenciennes, 1835) from the North Argentinian Coast by Otoliths Shape Analysis
by Santiago Morawicki, Patricio J. Solimano and Alejandra V. Volpedo
Fishes 2022, 7(4), 155; https://doi.org/10.3390/fishes7040155 - 29 Jun 2022
Cited by 5 | Viewed by 2251
Abstract
The marine silverside (Odontesthes argentinensis) is an euryhaline species, distributed along the southwest coast of the Atlantic Ocean, present in estuaries, brackish coastal lagoons and shallow marine waters. It is a significant economic resource for local fisheries in southern Brazil, Uruguay [...] Read more.
The marine silverside (Odontesthes argentinensis) is an euryhaline species, distributed along the southwest coast of the Atlantic Ocean, present in estuaries, brackish coastal lagoons and shallow marine waters. It is a significant economic resource for local fisheries in southern Brazil, Uruguay and Argentina. The aim of this work was to contribute to knowledge on the stock spatial structure of the silverside, using otolith shape analysis, based on samples from nine locations in the Argentinian Sea, covering a large distribution range of the species. A combination of elliptic Fourier descriptors, Wavelet coefficients and otolith Shape indices were explored by multivariate statistical methods. The application of wavelet and combined wavelet, Fourier and Shape Indices were the most effective variables to discriminate between sampling sites (7.42 total error). PERMANOVA analysis of otolith shape revealed multivariate significant differences between north versus south locations (p < 0.0001). The results obtained show that the spatial structure of O. argentinensis presents a North–South gradient with marked differences between the extreme localities of the north (Mar del Plata, Quequén) with more elliptical shapes than those in the south (San Blas, San Antonio Este) and an isolated group conformed by Puerto Lobos. Full article
(This article belongs to the Special Issue Otoliths and Their Applications in Fishery Science)
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14 pages, 3455 KiB  
Article
Revealing Population Connectivity of the Estuarine Tapertail Anchovy Coilia nasus in the Changjiang River Estuary and Its Adjacent Waters Using Otolith Microchemistry
by Tao Jiang, Hongbo Liu, Yuhai Hu, Xiubao Chen and Jian Yang
Fishes 2022, 7(4), 147; https://doi.org/10.3390/fishes7040147 - 23 Jun 2022
Cited by 7 | Viewed by 2010
Abstract
The estuarine tapertail anchovy, Coilia nasus, is a migratory fish with high economic value in China. We collected fish from the Changjiang River (the Yangtze River) estuary, the Qiantang River estuary, and the southern Yellow Sea, and studied their relationships using otolith elemental [...] Read more.
The estuarine tapertail anchovy, Coilia nasus, is a migratory fish with high economic value in China. We collected fish from the Changjiang River (the Yangtze River) estuary, the Qiantang River estuary, and the southern Yellow Sea, and studied their relationships using otolith elemental and stable isotopic microchemistry signatures to assess the population connectivity of C. nasus. Results show that, in addition to Ca, other elements were present in the otolith core. The δ18O, Na/Ca, Fe/Ca, and Cu/Ca values of the Qiantang population were significantly higher than those of the others, whereas its δ13C and Ba/Ca values were found to be significantly lower. Otolith multi-element composition and stable isotope ratios differed significantly between the Qiantang and Changjiang estuary groups (p < 0.05); however, no difference was observed between the latter and the Yellow Sea group. Cluster analysis, linear discriminant analysis, and a self-organizing map strongly suggest possible connectivity between the fish populations of the Changjiang estuary and Yellow Sea, while the population of the Qiantang River estuary appears to be independent. Notably, results suggest a much closer connectivity between the fish populations of the Changjiang River and the Yellow Sea. Full article
(This article belongs to the Special Issue Otoliths and Their Applications in Fishery Science)
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17 pages, 1979 KiB  
Article
Regional Population Structure of the European Eel at the Southern Limit of Its Distribution Revealed by Otolith Shape Signature
by Ana Moura, Ester Dias, Rodrigo López and Carlos Antunes
Fishes 2022, 7(3), 135; https://doi.org/10.3390/fishes7030135 - 07 Jun 2022
Cited by 6 | Viewed by 3163
Abstract
Given the European eel population’s marked decrease since the 1980s, it has become urgent to collect information describing its regional population structure to improve management plans. The Minho River (NW-Portugal, SW-Europe) is an important basin for the eel at the southern limit of [...] Read more.
Given the European eel population’s marked decrease since the 1980s, it has become urgent to collect information describing its regional population structure to improve management plans. The Minho River (NW-Portugal, SW-Europe) is an important basin for the eel at the southern limit of its distribution, but the species is poorly described. Thus, we aimed to study the structure of the European eel population in the Minho River using otolith shape analysis, which has proven to be effective in discriminating fish groups experiencing different environmental conditions through ontogeny. Our results showed complete discrimination between the two main types of habitats studied (tributaries and estuaries). Otoliths of eels from the estuary were rectangular and elliptic, whereas in the tributaries they presented a more round and circular form. Eels collected in both habitats were mostly yellow-stage eels with a similar age range, but the eels from the tributaries showed smaller length-at-age and lower body condition than those collected in the estuary. Additionally, the sex ratio was skewed towards males in the tributaries and females in the estuary. This study reveals that there are at least two distinct groups of eels in this basin, likely with different development characteristics. Full article
(This article belongs to the Special Issue Otoliths and Their Applications in Fishery Science)
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16 pages, 1428 KiB  
Article
Fidelity to Natal Tributary Streams by Kokanee Following Introduction to a Large Oligotrophic Reservoir
by J. Mark Shrimpton, Paige W. Breault and Luc A. Turcotte
Fishes 2022, 7(3), 123; https://doi.org/10.3390/fishes7030123 - 30 May 2022
Cited by 2 | Viewed by 1747
Abstract
The WAC Bennett Dam was completed in 1968 and impounded the Upper Peace River to form the Williston Reservoir in north central British Columbia. In 1990, an enhancement project was initiated to stock Columbia River Kokanee (non-anadromous Sockeye Salmon; Oncorhynchus nerka) from [...] Read more.
The WAC Bennett Dam was completed in 1968 and impounded the Upper Peace River to form the Williston Reservoir in north central British Columbia. In 1990, an enhancement project was initiated to stock Columbia River Kokanee (non-anadromous Sockeye Salmon; Oncorhynchus nerka) from southeastern British Columbia into tributary streams that drained into regions of the reservoir that were accessible by anglers. The current distribution of spawning Columbia-origin Kokanee in the Williston Reservoir watershed, however, does not reflect the locations where these fish were initially stocked and suggests extensive straying. Whether or not Kokanee will develop fidelity to specific spawning locations is not known, but it is important information to effectively manage these introduced fish. We used otolith microchemistry to estimate fidelity to natal streams by Columbia-origin Kokanee in the Williston Reservoir. Otolith elemental signatures for the region of the otolith that formed during the larval period and characterized the natal redd environment showed considerable variation among samples. Natal signatures tended to cluster for each river but not for all spawners, suggesting elemental signatures from other rivers. Homing to one of the four natal streams we examined was classified to be 73% based on linear discriminant analysis, although variation in the elemental signatures within each group suggests that homing by Kokanee to specific natal streams may be as low as 55%. Based on similarity of water elemental signatures for tributaries within large rivers, however, the proportion of fish that returned to their general region was likely higher and estimated to be approximately 83%. The result of regional homing could be reproductive isolation and adaptation to local conditions. It is unclear, however, if the current estimated level of straying will limit genetic differentiation and prevent local adaptation. Full article
(This article belongs to the Special Issue Otoliths and Their Applications in Fishery Science)
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11 pages, 5038 KiB  
Article
DeepOtolith v1.0: An Open-Source AI Platform for Automating Fish Age Reading from Otolith or Scale Images
by Dimitris V. Politikos, Nikolaos Sykiniotis, Georgios Petasis, Pavlos Dedousis, Alba Ordoñez, Rune Vabø, Aikaterini Anastasopoulou, Endre Moen, Chryssi Mytilineou, Arnt-Børre Salberg, Archontia Chatzispyrou and Ketil Malde
Fishes 2022, 7(3), 121; https://doi.org/10.3390/fishes7030121 - 29 May 2022
Cited by 3 | Viewed by 3808
Abstract
Every year, marine scientists around the world read thousands of otolith or scale images to determine the age structure of commercial fish stocks. This knowledge is important for fisheries and conservation management. However, the age-reading procedure is time-consuming and costly to perform due [...] Read more.
Every year, marine scientists around the world read thousands of otolith or scale images to determine the age structure of commercial fish stocks. This knowledge is important for fisheries and conservation management. However, the age-reading procedure is time-consuming and costly to perform due to the specialized expertise and labor needed to identify annual growth zones in otoliths. Effective automated systems are needed to increase throughput and reduce cost. DeepOtolith is an open-source artificial intelligence (AI) platform that addresses this issue by providing a web system with a simple interface that automatically estimates fish age by combining otolith images with convolutional neural networks (CNNs), a class of deep neural networks that has been a dominant method in computer vision tasks. Users can upload otolith image data for selective fish species, and the platform returns age estimates. The estimates of multiple images can be exported to conduct conclusions or further age-related research. DeepOtolith currently contains classifiers/regressors for three fish species; however, more species will be included as related work on ageing will be tested and published soon. Herein, the architecture and functionality of the platform are presented. Current limitations and future directions are also discussed. Overall, DeepOtolith should be considered as the first step towards building a community of marine ecologists, machine learning experts, and stakeholders that will collaborate to support the conservation of fishery resources. Full article
(This article belongs to the Special Issue Otoliths and Their Applications in Fishery Science)
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13 pages, 5179 KiB  
Article
Inter-Otolith Differences in Strontium Markings: A Case Study on the Juvenile Crucian Carp Carassius carassius (Linnaeus, 1758)
by Yahua Zhu, Tao Jiang, Xiubao Chen, Hongbo Liu, Quinton Phelps and Jian Yang
Fishes 2022, 7(3), 112; https://doi.org/10.3390/fishes7030112 - 15 May 2022
Cited by 3 | Viewed by 3077
Abstract
The release of hatchery-reared fish fry for restocking is important for the enrichment of fishery resources; however, the effective evaluation of the success rate of marking such fish is challenging. We exposed juvenile crucian carp (Carassius carassius) to a single concentration [...] Read more.
The release of hatchery-reared fish fry for restocking is important for the enrichment of fishery resources; however, the effective evaluation of the success rate of marking such fish is challenging. We exposed juvenile crucian carp (Carassius carassius) to a single concentration of SrCl2·6H2O for 5 d and evaluated the efficiency of Sr marking of the fish otoliths (sagittae, asterisci, and lapilli) using an electron probe micro-analyzer. Sr marking signatures formed a peak in all otolith types, with a marking success rate of 100%. The ratio of Sr to Ca in the lapilli and sagittae was higher than that in the asterisci. It took 2 d from the beginning of immersion to the deposition of Sr on the lapilli and sagittae, and the time delay for asterisci was 1 d. For the lapilli and sagittae, it took 16 d to terminate Sr marking and fully recover to the pre-marking Sr level, whereas it was 12 d for the asterisci. The application of the Sr dose had no effect on the survival or growth of the carp. This study demonstrated that the lapilli are the most suitable otolith type for Sr marking observations in crucian carp and provides a theoretical basis and technical support for carp restocking using the Sr marking approach. Full article
(This article belongs to the Special Issue Otoliths and Their Applications in Fishery Science)
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13 pages, 1960 KiB  
Article
The Lifetime Migratory History of Anadromous Brook Trout (Salvelinus fontinalis): Insights and Risks from Pesticide-Induced Fish Kills
by Scott D. Roloson, Kyle M. Knysh, Sean J. Landsman, Travis L. James, Brendan J. Hicks and Michael R. van den Heuvel
Fishes 2022, 7(3), 109; https://doi.org/10.3390/fishes7030109 - 11 May 2022
Cited by 2 | Viewed by 2603
Abstract
Brook trout populations in Prince Edward Island, Canada, have experienced over 50 pesticide-related fish kills since the 1960s. Life history evaluation of large sea-run brook trout recovered following two fish kill events was compared with a reference river using strontium:calcium otolith microchemistry. This [...] Read more.
Brook trout populations in Prince Edward Island, Canada, have experienced over 50 pesticide-related fish kills since the 1960s. Life history evaluation of large sea-run brook trout recovered following two fish kill events was compared with a reference river using strontium:calcium otolith microchemistry. This study examined the dual hypotheses that anadromous brook trout are more likely to arise from sea-run mothers, and that freshwater entry timing makes them vulnerable to pesticide-induced fish kills. A total 89% of the fish exhibited an anadromous life history, and 77% of these were offspring of anadromous mothers, suggesting that anadromy is dominant in progeny of sea-run mothers. This study adds to our understanding of the maternal inheritance of anadromy in sea-run brook trout populations. Additionally, freshwater entry precedes the majority of fish kill events, illustrating that the overlap between migration and pesticide runoff contributes to the cumulative population risks to sea-run brook trout. Full article
(This article belongs to the Special Issue Otoliths and Their Applications in Fishery Science)
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11 pages, 2294 KiB  
Article
Fluctuating Asymmetry in Asteriscii Otoliths of Common Carp (Cyprinus carpio) Collected from Three Localities in Iraqi Rivers Linked to Environmental Factors
by Laith Jawad and Kélig Mahé
Fishes 2022, 7(2), 91; https://doi.org/10.3390/fishes7020091 - 15 Apr 2022
Cited by 7 | Viewed by 2812
Abstract
Otoliths, calcified structures in the inner ears, are used to estimate fish age, and their shape is an efficient fish stock identification tool. Otoliths are thus very important for the management and assessment of commercial stocks. However, most studies have used left or [...] Read more.
Otoliths, calcified structures in the inner ears, are used to estimate fish age, and their shape is an efficient fish stock identification tool. Otoliths are thus very important for the management and assessment of commercial stocks. However, most studies have used left or right otoliths, chosen arbitrarily without evaluation of the difference between these otoliths. In this study, the asteriscii otoliths from 263 common carp (Cyprinus carpio; Linnaeus, 1758) were sampled in three Iraqi rivers to test the potential asymmetry and the geographical effect on otolith growth from three measurements (length, width and weight), and on shape from two shape indices (ellipticity and form-factor). Among all asteriscii otolith features, there was significant fluctuating asymmetry between fish length and every otolith descriptor. At one fish length, the size and/or the shape of otoliths could be different between two individuals and/or between left and right asteriscii otoliths for the same individual. Moreover, the relationship between fish length and otolith shape/growth was significantly dependent on the studied geographical area and, more especially, the environmental effects as the water temperature and pH. Finally, the relationships between fish length and otolith shape indices showed that the otolith evolves into the elliptical shape during the life of the fish. To use the otolith shape, it is essential to take into account the developmental stage of individuals to integrate the ontogenetic effect. Our results highlight the importance of verifying potential otolith asymmetry, especially for the asteriscii otoliths (lagenar otoliths) before their use in fisheries research. Full article
(This article belongs to the Special Issue Otoliths and Their Applications in Fishery Science)
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15 pages, 1914 KiB  
Article
Assessing the Speciation of Lutjanus campechanus and Lutjanus purpureus through Otolith Shape and Genetic Analyses
by Angel Marval-Rodríguez, Ximena Renán, Gabriela Galindo-Cortes, Saraí Acuña-Ramírez, María de Lourdes Jiménez-Badillo, Hectorina Rodulfo, Jorge L. Montero-Muñoz, Thierry Brulé and Marcos De Donato
Fishes 2022, 7(2), 85; https://doi.org/10.3390/fishes7020085 - 07 Apr 2022
Cited by 3 | Viewed by 2761
Abstract
Based on their morphological and genetic similarity, several studies have proposed that Lutjanus campechanus and Lutjanus purpureus are the same species, but there is no confirmed consensus yet. A population-based study concerning otolith shape and genetic analyses was used to evaluate if L [...] Read more.
Based on their morphological and genetic similarity, several studies have proposed that Lutjanus campechanus and Lutjanus purpureus are the same species, but there is no confirmed consensus yet. A population-based study concerning otolith shape and genetic analyses was used to evaluate if L. campechanus and L. purpureus are the same species. Samples were collected from populations in the southwestern Gulf of Mexico and the Venezuelan Caribbean. Otolith shape was evaluated by traditional and outline-based geometric morphometrics. Genetic characterization was performed by sequencing the mtDNA control region and intron 8 of the nuclear gene FASD2. The otolith shape analysis did not indicate differences between species. A nested PERMANOVA identified differences in otolith shape for the nested population factor (fishing area) in morphometrics and shape indexes (p = 0.001) and otolith contour (WLT4 anterior zone, p = 0.005 and WLT4 posterodorsal zone, p = 0.002). An AMOVA found the genetic variation between geographic regions to be 10%, while intrapopulation variation was 90%. Network analysis identified an important connection between haplotypes from different regions. A phylogenetic analysis identified a monophyletic group formed by L. campechanus and L. purpureus, suggesting insufficient evolutionary distances between them. Both otolith shape and molecular analyses identified differences, not between the L. campechanus and L. purpureus species, but among their populations, suggesting that western Atlantic red snappers are experiencing a speciation process. Full article
(This article belongs to the Special Issue Otoliths and Their Applications in Fishery Science)
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16 pages, 3310 KiB  
Article
Automatic Fish Age Determination across Different Otolith Image Labs Using Domain Adaptation
by Alba Ordoñez, Line Eikvil, Arnt-Børre Salberg, Alf Harbitz and Bjarki Þór Elvarsson
Fishes 2022, 7(2), 71; https://doi.org/10.3390/fishes7020071 - 18 Mar 2022
Cited by 12 | Viewed by 3574
Abstract
The age determination of fish is fundamental to marine resource management. This task is commonly done by analysis of otoliths performed manually by human experts. Otolith images from Greenland halibut acquired by the Institute of Marine Research (Norway) were recently used to train [...] Read more.
The age determination of fish is fundamental to marine resource management. This task is commonly done by analysis of otoliths performed manually by human experts. Otolith images from Greenland halibut acquired by the Institute of Marine Research (Norway) were recently used to train a convolutional neural network (CNN) for automatically predicting fish age, opening the way for requiring less human effort and availability of expertise by means of deep learning (DL). In this study, we demonstrate that applying a CNN model trained on images from one lab (in Norway) does not lead to a suitable performance when predicting fish ages from otolith images from another lab (in Iceland) for the same species. This is due to a problem known as dataset shift, where the source data, i.e., the dataset the model was trained on have different characteristics from the dataset at test stage, here denoted as target data. We further demonstrate that we can handle this problem by using domain adaptation, such that an existing model trained in the source domain is adapted to perform well in the target domain, without requiring extra annotation effort. We investigate four different approaches: (i) simple adaptation via image standardization, (ii) adversarial generative adaptation, (iii) adversarial discriminative adaptation and (iv) self-supervised adaptation. The results show that the performance varies substantially between the methods, with adversarial discriminative and self-supervised adaptations being the best approaches. Without using a domain adaptation approach, the root mean squared error (RMSE) and coefficient of variation (CV) on the Icelandic dataset are as high as 5.12 years and 28.6%, respectively, whereas by using the self-supervised domain adaptation, the RMSE and CV are reduced to 1.94 years and 11.1%. We conclude that careful consideration must be given before DL-based predictors are applied to perform large scale inference. Despite that, domain adaptation is a promising solution for handling problems of dataset shift across image labs. Full article
(This article belongs to the Special Issue Otoliths and Their Applications in Fishery Science)
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8 pages, 1338 KiB  
Article
Age, Growth, and Utility of Otolith Morphometrics as Predictors of Age in the European Barracuda, Sphyraena sphyraena (Sphyraenidae): Preliminary Data
by Josipa Ferri and Anđela Brzica
Fishes 2022, 7(2), 68; https://doi.org/10.3390/fishes7020068 - 17 Mar 2022
Cited by 1 | Viewed by 2454
Abstract
Age and growth of the European barracuda, Sphyraena sphyraena, were determined by examining sagittal otoliths belonging to fish sampled in the eastern Adriatic Sea, as the northernmost region of the Mediterranean. A total of 113 specimens (59 females, 53 males, and one [...] Read more.
Age and growth of the European barracuda, Sphyraena sphyraena, were determined by examining sagittal otoliths belonging to fish sampled in the eastern Adriatic Sea, as the northernmost region of the Mediterranean. A total of 113 specimens (59 females, 53 males, and one individual of indeterminate sex), ranging from 23.4 to 42.5 cm in total length, were analyzed. The maximum observed age was 5 years for both females and males, and this barracuda population was dominated by 3 year old fish. Growth was described by the von Bertalanffy growth curve (L∞ = 55.58 cm, K = 0.12 year−1, t0 = −4.29 year, R2 = 0.580), and the growth performance index (Φ’) was 2.57. Otolith length, width, and mass were measured, and the utility of these morphometrics as predictors of age in S. sphyraena was evaluated. The results showed that counting otolith annuli produced a better estimation of age than proposed linear models based on relationships between observed fish age and otolith morphometrics. In comparison with age and growth data available in the literature for S. sphyraena, our results from the Adriatic Sea provide more insights into the life-history traits of this species and can be used in the future effective management and conservation. Full article
(This article belongs to the Special Issue Otoliths and Their Applications in Fishery Science)
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11 pages, 2225 KiB  
Article
A Pilot Study Assessing a Concentration of 100 mg/L Alizarin Complexone (ALC) to Mark Calcified Structures in Hypophthalmichthys molitrix
by Yahua Zhu, Tao Jiang, Xiubao Chen, Hongbo Liu, Quinton Phelps and Jian Yang
Fishes 2022, 7(2), 66; https://doi.org/10.3390/fishes7020066 - 16 Mar 2022
Cited by 2 | Viewed by 2752
Abstract
The effectiveness of chemical compounds for marking hard tissues in juvenile silver carp (Hypophthalmichthys molitrix) is not well known. We analyzed the use of alizarin complexone (ALC) as a fluorescent marker to mark the various hard structures of juvenile silver carp. [...] Read more.
The effectiveness of chemical compounds for marking hard tissues in juvenile silver carp (Hypophthalmichthys molitrix) is not well known. We analyzed the use of alizarin complexone (ALC) as a fluorescent marker to mark the various hard structures of juvenile silver carp. Experimental fish (~2 months old) were randomly assigned to either control or marking groups, which were immersed in 0 or 100 mg/L ALC solutions, respectively, for 2 days. The otoliths, fin rays, and scales of the fish were then sampled, visualized using fluorescence microscopy, and evaluated after 10 days. The ALC treatment was effective for marking certain hard structures and the marking color was affected by the light source. There were no obvious differences in the marking efficiency of rays from pectoral, dorsal, ventral, anal, and caudal fins, but the lapilli and lateral line scales were marked most effectively from the sampled otolith and scale types, respectively. Our findings indicate that ALC immersion and fin ray and scale sampling can be used for the effective marking and non-lethal evaluation of hard structures in juvenile silver carp. Full article
(This article belongs to the Special Issue Otoliths and Their Applications in Fishery Science)
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11 pages, 2982 KiB  
Article
Growth and Microstructural Features in Otoliths of Larval and Juvenile Sinogastromyzon wui (F. Balitoridae, River Loaches) of the Upper Pearl River, China
by Minghui Gao, Zhiqiang Wu, Liangliang Huang, Xichang Tan, Mingsi Li and Haibo Huang
Fishes 2022, 7(2), 57; https://doi.org/10.3390/fishes7020057 - 01 Mar 2022
Cited by 3 | Viewed by 2878
Abstract
Otolith growth and microstructural features of fish are essential to the understanding of the early fish lifecycle. This paper assesses the features of otoliths from laboratory-reared larval and juvenile Sinogastromyzon wui (S. wui, 0 to 25 days post-hatching) that were obtained [...] Read more.
Otolith growth and microstructural features of fish are essential to the understanding of the early fish lifecycle. This paper assesses the features of otoliths from laboratory-reared larval and juvenile Sinogastromyzon wui (S. wui, 0 to 25 days post-hatching) that were obtained as eggs from the Shilong Reach of Xijiang River between April and August 2021. We observed the development of the three pairs of otoliths (lapilli, sagittae, and asterisci) and compared the shape changes and growth of the lapilli and sagittae, as well as the timing and deposition rate of increments of the lapilli. The lapilli and the sagittae were visible on hatching, whereas the asterisci were present at four days post-hatching (dph). The shape of the sagitta changed more obviously than that of the lapillus, and a strong correlation was observed between sagitta shape changes and fish ontogenesis. The otolith shape greatly modulated during the post-flexion larval stage (Post-FLS), it corresponded with the formation period of individual fins. Analysis of the microstructural features indicated that lapilli were the optimal otolith for age determination and increment deposition rate confirmation. Using regression analysis of the known age and the number of lapillus daily increments, we demonstrated that the lapillus developmental increments were deposited daily, and the first increment formed at two days post-hatching. Our conclusions support employing the lapillus increment deposition rate and the time of the first daily increments in the determination of the age of wild larval and juvenile S. wui. Full article
(This article belongs to the Special Issue Otoliths and Their Applications in Fishery Science)
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6 pages, 855 KiB  
Communication
Age and Growth of Quillback Rockfish (Sebastes maliger) at High Latitude
by Camron J. Christoffersen, Dennis K. Shiozawa, Andrew D. Suchomel and Mark C. Belk
Fishes 2022, 7(1), 38; https://doi.org/10.3390/fishes7010038 - 05 Feb 2022
Cited by 1 | Viewed by 2905
Abstract
Data on age and growth of fishes is critical for effective management; however, growth rates documented in one location may not be representative of other locations, especially for species that occur across wide geographic ranges. Sebastes maliger, quillback rockfish, occur across a [...] Read more.
Data on age and growth of fishes is critical for effective management; however, growth rates documented in one location may not be representative of other locations, especially for species that occur across wide geographic ranges. Sebastes maliger, quillback rockfish, occur across a broad latitudinal range, but their growth patterns have been quantified only in the southern part of their range. To provide information for S. maliger in the more northern part of its range, we report age and growth patterns derived from otolith analysis from a population collected in southeast Alaskan waters. In southeast Alaska mean annual growth increments for years 1 and 2 range from 60–80 mm, and for ages 6–9 annual growth increments average about 20 mm. From age 10 on average the annual growth increment is about 5 mm. These data can be used in conjunction with harvest data to manage stocks of S. maliger in Alaskan waters. Full article
(This article belongs to the Special Issue Otoliths and Their Applications in Fishery Science)
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