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The discovery of radically different antifreeze proteins (AFPs) in fishes during the 1970s and 1980s suggested that these proteins had recently and independently evolved to protect teleosts from freezing in icy seawater. Early forays into the isolation and characterization of AFP genes in these fish showed they were massively amplified, often in long tandem repeats. The work of many labs in the 1980s onward led to the discovery and characterization of AFPs in other kingdoms, such as insects, plants, and many different microorganisms. The distinct ice-binding property that these ice-binding proteins (IBPs) share has facilitated their purification through adsorption to ice, and the ability to produce recombinant versions of IBPs has enabled their structural characterization and the mapping of their ice-binding sites (IBSs) using site-directed mutagenesis. One hypothesis for their ice affinity is that the IBS organizes surface waters into an ice-like pattern that freezes the protein onto ice. With access now to a rapidly expanding database of genomic sequences, it has been possible to trace the origins of some fish AFPs through the process of gene duplication and divergence, and to even show the horizontal transfer of an AFP gene from one species to another. Key words: gene duplication and divergence, multigene family, ice-binding proteins, ice nucleation, lateral gene transfer La decouverte de proteines antigel (PAG) radicalement differentes chez les poissons au cours des annees 1970 et 1980 a suggere que ces proteines avaient recemment et independamment evolue pour proteger les teleosteens de la congelation dans l'eau de mer glacee. Les premieres tentatives d'isolement et de caracterisation des genes de PAG chez ces poissons ont montre qu'ils etaient amplifies de facon massive, souvent en longues repetitions en tandem. Les travaux de nombreux laboratoires a partir des annees 1980 ont conduit a la decouverte et a la caracterisation de PAG dans d'autres regnes tels que les insectes, les plantes et de nombreux micro-organismes differents. La propriete distincte de lier la glace que ces proteines de liaison a la glace (PLG) partagent a facilite leur purification par adsorption a la glace, et la capacite de produire des versions recombinantes des PLG a permis leur caracterisation structurelle et la cartographie de leurs sites de liaison a la glace par mutagenese dirigee. L'une des hypotheses en ce qui concerne leur affinite pour la glace est que le site de liaison a la glace organise les eaux de surface en un motif semblable a la glace, ce qui fige la proteine sur la glace. Grace a l'acces a une base de donnees de sequences genomiques qui est en expansion rapide, il a ete possible de tracer l'origine de certaines PAG des poissons a travers le processus de duplication et de divergence des genes, et meme de montrer le transfert horizontal d'un gene de PAG d'une espece a une autre. [Traduit par la Redaction] Mots-cles : duplication et divergence de genes, famille multigenique, proteines de liaison a la glace, nucleation de la glace, transfert lateral de genes, In graduate school, it is not just what you get to know, it is also who you get to know As an undergraduate student at the University of Wales, I [...]

Identifying changes in fish growth is important for accurate scientific advice used for fisheries management, because environmental change is affecting fish growth and size-at-age is a critical component of contemporary stock assessment methods. Growth-increment biochronologies are time series of growth-increments derived from hard parts of marine organisms that may reveal dynamics of somatic fish growth. Here we use time series of otolith increments of two fish stocks to fit and compare a biologically derived growth model and a generalized statistical model. Both models produced similar trajectories of annual growth trends, but the biologically based one was more precise and predicted smaller interannual fluctuations than the statistical model. The biologically based model strongly indicated covariance between anabolic and catabolic rates among individuals. Otolith size-at-age did not closely match fish length-at-age, and consequently the growth model could not accurately hindcast observed fish length-at-age. For these reasons, fitted growth dynamics from otolith biochronologies may best suited to identify growth rate fluctuations, understand past drivers of growth dynamics, and improve ecological forecast in the face of rapid environmental change. La determination des variations de la croissance des poissons est importante pour la formulation d'avis scientifiques exacts pour la gestion des peches, puisque les changements environnementaux ont une incidence sur la croissance des poissons et que la taille selon l'age est un element cle des methodes contemporaines d'evaluation des stocks. Les biochronologies d'increments de croissance sont des series chronologiques d'increments de croissance obtenues de parties dures d'organismes marins, qui peuvent reveler la dynamique de la croissance somatique des poissons. Nous utilisons des series chronologiques d'increments de croissance d'otolites provenant de deux stocks de poissons pour caler et comparer un modele de croissance fonde sur la biologie et un modele statistique generalise. Les deux modeles produisent des trajectoires semblables des tendances de la croissance annuelle, mais le modele biologique est plus precis et predit de plus petites fluctuations interannuelles que le modele statistique. Le modele biologique fait clairement ressortir la covariance des taux anaboliques et cataboliques individuels. La taille selon l'age des otolites ne concorde pas bien avec la taille selon l'age des poissons et, par consequent, le modele de croissance ne peut produire des predictions a posteriori exactes de la longueur des poissons selon l'age. Pour ces raisons, la plus grande utilite de la dynamique de croissance obtenue a partir de biochronologies d'otolites pourrait etre pour la determination des fluctuations des taux de croissance dans le but de comprendre les facteurs determinants passes de la dynamique de croissance et d'ameliorer les previsions des conditions ecologiques dans un contexte de changements climatiques rapides. [Traduit par la Redaction], Introduction Understanding the processes underlying growth is critical for modeling fish population dynamics, as size-at-age is a critical component of contemporary age- and size-structured stock assessment methods (Lorenzen 2016). Environmentally [...]

The biological parameters needed to interpret isotopic field data on food webs-- namely isotopic incorporation and discrimination ([[DELTA].sup.13]C and [[DELTA].sup.15]N)--are unknown for many animals. We investigated the effects of temperature on carbon and nitrogen incorporation and discrimination in creek chub (Semotilus atromaculatus) and white sucker (Catostomus commersonii) by rearing wild-caught fish on a distinct diet at 12 and 20[degrees]C for 160 days. Mass specific growth rates were higher at 20[degrees]C. Isotopic turnover was mainly influenced by metabolic processes as opposed to growth in both species, especially white sucker. Cold-reared fish had slower rates of isotopic incorporation and higher isotopic residence times than warmreared fish. Discrimination factors were generally smaller for [[DELTA].sup.15]N (range = 1.9 to 3.0) and larger for [[DELTA].sup.13]C (range = 1.4 to 2.3) than values reported for other fishes. Variable temperature effects on discrimination suggests unmeasured effects of the experimental diet which will require additional experimentation to tease apart. These results support the hypothesis that metabolic rates are correlated with isotopic incorporation rates in animals dependent on environmental temperature. Les parametres biologiques necessaires a l'interpretation de donnees isotopiques de terrain sur les reseaux trophiques, notamment sur l'incorporation et la discrimination isotopiques ([[DELTA].sup.13]C et [[DELTA].sup.15]N), ne sont pas connus pour de nombreux animaux. Nous avons examine les effets de la temperature sur l'incorporation et la discrimination du carbone et de l'azote chez le mulet a cornes (Semotilus atromaculatus) et le meunier noir (Catostomus commersonii) en elevant des poissons captures a l'etat sauvage sur un regime alimentaire distinct a 12 et 20[degrees]C pendant 160 jours. Les taux de croissance en fonction de la masse sont plus eleves a 20[degrees]C. Le renouvellement isotopique est principalement influence par des processus metaboliques plutot que par la croissance chez les deux especes, en particulier le meunier noir. Les poissons eleves a basse temperature presentent des taux d'incorporation isotopique plus faibles et des temps de residence isotopique plus eleves que les poissons eleves a haute temperature. Les facteurs de discrimination sont generalement plus faibles pour [[DELTA].sup.15]N (fourchette de 1,9 a 3,0) et plus eleves pour [[DELTA].sup.13]C (fourchette de 1,4 a 2,3) que les valeurs publiees pour d'autres poissons. Des effets variables de la temperature sur la discrimination indiqueraient la presence d'effets non mesures du regime alimentaire experimental qui ne pourront etre departages que par de nouvelles experimentations. Ces resultats appuient l'hypothese voulant que les taux metaboliques soient correles aux taux d'incorporation isotopique chez les animaux qui dependent de la temperature du milieu ambiant. [Traduit par la Redaction], Introduction Freshwater fishes are important components of aquatic habitats, but empirical characterization of their diet and feeding interactions remains challenging due to the diversity of foods used by fish and [...]

Most previous systems for quantifying ventilatory flow in fish involve prior anesthesia and difficult surgery to sew or glue membranes to the animal, which are undoubtedly stressful. By modification of the original 'van Dam box' design and incorporation of an electromagnetic blood flow probe, we have developed a less invasive system that avoids these problems and provides breath-to-breath measurements of ventilatory flow in real time. The fish can be quickly moved in and out of the apparatus, facilitating repeated measurements on the same animal after different treatments. We have used the system to document the hyperventilatory and hypoventilatory responses to environmental hypoxia and hyperoxia, respectively, in both ~400-g trout (Oncorhynchus mykiss) and 10-g goldfish (Carassius auratus); the method is easily adaptable to fish of other sizes. Separate experiments on trout have demonstrated that responses to these treatments in buccal pressure amplitude, breathing frequency, and ventilation index are not altered by the attachments used in the apparatus. This less invasive methodology may prove more acceptable to animal ethics committees. La plupart des systemes existants utilises pour quantifier le debit ventilatoire de poissons necessitent une anesthesie prealable et une intervention chirurgicale difficile pour coudre ou coller des membranes au specimen et entrainent assurement un stress. En modifiant le schema de << boite de van Dam >> original et en y integrant une sonde electromagnetique de debit sanguin, nous avons mis au point un systeme moins effractif qui evite ces ecueils et produit des mesures en temps reel du debit ventilatoire entre respirations. Les poissons peuvent etre places dans l'appareil et en etre retires rapidement, ce qui facilite des mesures repetees sur le meme specimen apres differents traitements. Nous avons utilise le systeme pour documenter les reactions hyperventilatoire et hypoventilatoire a une hypoxie et une hyperoxie ambiantes, respectivement, chez des truites (Oncorhynchus mykiss) de ~400 g et des carassins dores (Carassius auratus) de ~10 g; la methode peut facilement etre adaptee a des poissons d'autres tailles. D'autres experiences sur des truites ont demontre que les reponses a ces traitements en ce qui concerne l'amplitude de la pression buccale, la frequence des respirations et l'indice de ventilation ne sont pas modifiees par les pieces fixees au specimen qui font partie du dispositif. Des comites d'ethique animale pourraient trouver plus acceptable cette methode moins effractive. [Traduit par la Redaction], Introduction The measurement of [??]w, the total ventilatory flow of water (i.e., ventilation volume) through the gills, is fundamental to understanding the respiratory physiology of fish but is not easy [...]

In 'The Great Fish Pain Debate' (Issues, Summer 2010), Troy Vettese, Becca Franks, and Jennifer Jacquet rightly state that in Germany the assumption that fish feel pain resulted in court [...]

Balancing foraging opportunities with predation risk can promote complex behavioural strategies in juvenile fishes, particularly in northern temperate environments with short growing seasons. To test how predation experience may influence foraging effort and risk assessment of juvenile lake sturgeon (Acipenser fulvescens Rafinesque, 1817), flight response and substrate preference behavioural measurements were taken during critical life periods of early exogenous feeding (~60 days post fertilization (dpf)) and pre-winter (~160 dpf). Lake sturgeon were placed in arenas with partial cover and exposed white plastic bottom. Chemical alarm cue (AC) was introduced to predator naïve individuals in the presence or absence of food over the exposed portion of the arena to simulate risk sensitive foraging over diurnal and seasonal periods. The same protocol was run on predator-experienced individuals, which were classically conditioned to predator cue (PC) prior to the trials. Whole-body cortisol measures were also taken to determine the physiological response to predation experience. Results suggest a propensity to forage in spite of predation risk during the naïve ~60 dpf trials and highlight context-specific anti-predator responses of naïve and experienced lake sturgeon. Elevated basal whole-body cortisol levels and reduced body condition (p < 0.05) were observed with increased predator experience. Key words: lake sturgeon, Acipenser fulvescens, foraging, learning, predation, physiology. La recherche d'un équilibre entre les occasions de quête de nourriture et le risque de prédation peut favoriser des stratégies comportementales complexes chez les jeunes poissons, particulièrement dans les milieux tempérés nordiques où les saisons de croissance sont courtes. Pour vérifier comment l'expérience de prédation pourrait influencer l'effort de quête de nourriture et l'évaluation du risque chez les esturgeons jaunes (Acipenser fulvescens Rafinesque, 1817) juvéniles, des mesures comportementales de la réaction de fuite et des préférences en matière de substrat ont été prises durant les périodes critiques du début de l'étape d'alimentation exogène (~60 jours après la fécondation (jaf)) et avant l'hiver (~160 jaf). Des esturgeons jaunes ont été placés dans des enceintes partiellement couvertes et dotées d'un fond en plastique blanc exposé. Des spécimens sans expérience de prédateurs ont été exposés à un signal d'alarme chimique en présence ou en l'absence de nourriture dans la partie exposée de l'enceinte afin de simuler une quête de nourriture sensible au risque durant des périodes diurnes et saisonnières. Le même protocole a été appliqué à des spécimens avec expérience de prédateurs, conditionnés de manière classique à un signal de prédateur avant les essais. Des mesures de la concentration corporelle globale de cortisol ont été prises afin de déterminer la réaction physiologique à l'expérience de prédation. Les résultats indiqueraient une propension à la quête de nourriture en dépit de l'existence d'un risque de prédation durant les essais à ~60 jaf sur des poissons naïfs et soulignent le fait que les réactions anti-prédation des esturgeons naïfs et expérimentés dépendent du contexte. Une élévation des concentrations corporelles globales de base de cortisol et une diminution de l'embonpoint (p < 0,05) étaient associées à une plus grande expérience de prédateurs. [Traduit par la Rédaction] Mots-clés: esturgeon jaune, Acipenser fulvescens, quête de nourriture, apprentissage, prédation, physiologie., Introduction The trade-off between feeding and avoiding potential predation threat is often faced by foraging animals (Elgar 1989). For the individual, it is beneficial to promote avoidance behaviour proportional to [...]

Spiny dogfish (Squalus acanthias) and smoothhound (Mustelus canis) sharks in the northwest Atlantic undergo seasonal migrations driven by changes in water temperature. However, the recognized thermal habitats of these regional populations are poorly described. Here, we report the thermal range, catch frequency with bottom temperature, and catch frequency with time of year for both shark species in Narragansett Bay, Rhode Island. Additionally, we describe levels of two thermal stress response indicators, heat-shock protein 70 and trimethylamine N-oxide, with an experimental increase in water temperature from 15 [degrees]C to 21 [degrees]C. Our results show that S. acanthias can be found in this region year-round and co-occurs with M. canis from June to November. Further, adult S. acanthias routinely inhabits colder waters than M. canis (highest catch frequencies at bottom temperatures of 10 [degrees]C and 21 [degrees]C, respectively), but both exhibit similar upper thermal ranges in this region (bottom temperatures of 22-23 [degrees]C). Additionally, acute exposure to a 6 [degrees]C increase in water temperature for 72 hours leads to a nearly threefold increase in heat-shock protein 70 levels in S. acanthias but not M. canis. Therefore, these species display differences in their thermal tolerance and stress response with experimental exposure to 21 [degrees]C, a common summer temperature in Narragansett Bay. Further, in temperature-stressed S. acanthias there is no accumulation of trimethylamine N-oxide. At the whole-organism level, elasmobranchs' trimethylamine N-oxide regulatory capacity may be limited by other factors. Alternatively, elasmobranchs may not rely on trimethylamine N-oxide as a primary thermal protective mechanism under the conditions tested. Findings from this study are in contrast with previous research conducted with elasmobranch cells in vitro that showed accumulation of trimethylamine N-oxide after thermal stress and subsequent suppression of the heat-shock protein 70 response., Introduction Temperature is one of the primary environmental factors affecting organismal distribution and success. A number of marine species, including a variety of coastal sharks, rely on seasonal thermal cues [...]

Triploid salmonids have been shown to underperform in suboptimal environments. It is thought this might be due to having larger cells to accommodate the increased number of chromosomes and therefore effects on aerobic metabolism from having smaller cellular surface area to volume ratios. The goal of this study was to examine the aerobic metabolism of diploid and triploid white sturgeon (Acipenser transmontanus) in ambient (18 [degrees]C) and elevated water temperatures (24 [degrees]C). Resting and maximum metabolic rates, recovery time from exhaustive exercise, and surface area to volume ratios of erythrocytes and their nuclei in diploid and triploid sturgeon were evaluated. Triploid sturgeon had a reduced aerobic scope and hematological response (hematocrit and hemoglobin) to exhaustive exercise. A reduced surface area to volume ratio of erythrocytes in triploid sturgeon provides evidence that cellular surface area could be one mechanism limiting aerobic metabolism in triploid fishes. A lower aerobic scope found in triploid sturgeon may impact reproductive and somatic growth, yet more research is needed to determine implications for management decisions on farms and hatcheries. II a ete demontre que la performance de salmonides triploides dans des milieux suboptimaux est moins bonne que celle de salmonides diploides. Cela pourrait etre du au fait qu'ils ont des cellules plus grosses pour contenir leur plus grand nombre de chromosomes, ce qui aurait des effets sur le metabolisme aerobie associes aux rapports plus faibles de la surface et du volume des cellules. Le but de l'etude etait d'examiner le metabolisme aerobie d'esturgeons blancs (Acipenser transmontanus) diploides et triploides dans des temperatures ambiante (18 [degrees]C) et elevee (24 [degrees]C) de l'eau. Les metabolismes de base et maximum, le temps de recuperation d'un exercice epuisant et les rapports de la surface et du volume d'erythrocytes et de leurs noyaux chez des esturgeons diploides et triploides ont ete evalues. L'exercice intensif s'est traduit par une amplitude aerobie et une reaction hematologique (hematocrite et hemoglobine) reduites chez les esturgeons triploides. Un rapport plus faible de la surface et du volume des erythrocytes chez les esturgeons triploides indique que la surface des cellules pourrait etre un facteur qui limite le metabolisme aerobie chez les poissons triploides. L'amplitude aerobie plus faible observee chez les esturgeons triploides pourrait avoir une incidence sur la croissance reproductive et somatique, mais plus de travaux sont necessaires afin d'en etablir l'importance en ce qui concerne les decisions de gestion pour les piscicultures et les ecloseries. [Traduit par la Redaction], Introduction Study of the relationship between ploidy and physiological performance in fishes, at any biological level, has thus far been mostly limited to salmonid species (see Benfey 1999 and Maxime [...]

Large marine predators often aggregate seasonally in discrete locations to take advantage of optimal foraging conditions, leading to spatial and temporal variation in their exposure on other species. However, our understanding of the impacts this exposure may have on the behavior and physiology of prey is poor, especially in marine systems. Here, we evaluated the non-consumptive effects of potential exposure to large sharks (white sharks, Carcharodon carcharias (Linnaeus, 1758)) on the stress physiology of an economically important teleost, the striped bass (Morone saxatilis (Walbaum, 1792)), off Cape Cod, Massachusetts, USA. We sampled fish in habitats that varied significantly in shark exposure across 5 months and over 2 years, evaluating blood physiology stress indicators (i.e., cortisol, glucose, and lactate concentrations) and reflex impairment. None of the blood parameters were influenced by shark exposure, although we did observe subtle temperature and seasonal effects. One of the three reflex tests (the vertical orientation test) was negatively affected by shark exposure, although the mechanistic basis for this finding is unclear. This work supports the notion that predictable sources of predation pressure tend not to manifest in stress-related costs in free-ranging prey, which has implications for shaping our understanding of how large sharks influence ecosystems through non-consumptive effects. Key words: glucocorticoids, non-consumptive effects, predation, stress, striped bass, Morone saxatilis, white shark, Carcharodon carcharias. Les grands predateurs marins se regroupent souvent sur une base saisonniere dans des lieux precis pour profiter de conditions d'approvisionnement optimales, ce qui mene a des variations spatiales et temporelles de l'exposition d'autres especes a leur presence. La comprehension des impacts de cette exposition sur le comportement et la physiologie des proies demeure toutefois limitee, particulierement en ce qui concerne les systemes marins. Nous evaluons les effets non destructeurs de l'exposition potentielle a de grands requins (grands requins blancs, Carcharodon carcharias (Linnaeus, 1758)) sur la physiologie du stress d'un teleosteen d'importance commerciale, le bar d'Amerique (Morone saxatilis (Walbaum, 1792)), au large de Cape Cod (Massachusetts, Etats-Unis). Nous avons echantillonne des poissons dans des habitats presentant une diversite d'exposition aux requins sur une duree de cinq mois et sur deux annees, pour evaluer des indicateurs sanguins de la physiologie du stress (c.-a-d. concentrations de cortisol, glucose et lactate) et l'alteration des reflexes. Aucun des parametres sanguins n'etait influence par l'exposition aux requins, de subtils effets de la temperature et de la saison ayant toutefois ete observes. Un des trois tests des reflexes (le test d'orientation verticale) a releve un effet negatif de l'exposition aux requins, bien que le fondement mecaniste de cet effet demeure mal compris. Ces travaux appuient la notion voulant que les sources previsibles de pression de predation n'aient pas tendance a se refleter dans les couts associes au stress chez les proies en liberte, une constatation importante pour la comprehension de l'influence qu'exercent, par l'entremise d'effets non destructeurs, les grands requins sur les ecosystemes. [Traduit par la Redaction] Mots-cles : glucocorticoides, effets non destructeurs, predation, stress, bar d'Amerique, Morone saxatilis, grand requin blanc, Carcharodon carcharias., Introduction Predators can affect prey directly, through consumption, and indirectly, through non-consumptive effects, also known as 'risk effects' (Lima and Dill 1990; Laundre 2010). These non-consumptive effects can have strong [...]

There is increasing concern about the effect of underwater noise on fish due to rising levels of anthropogenic noise. We performed experiments on the black bullhead (Ameiurus melas), a species with known hearing specializations and located within the Laurentian Great Lakes where there is considerable commercial and recreational boat traffic. We tested and compared physiology (baseline cortisol), behaviour (activity, sheltering), and morphology (ciliary bundles of hair cells) of bullhead to boat noise. At 140 dB re 1 [micro]Pa (-54.84 dB re 1 mx[s.sup.-2]), we saw clear behavioural effects in terms of both activity and sheltering levels despite no obvious morphological or physiological stress. Following both short- and long-period acute exposure to higher--but environmentally relevant--noise levels, bullhead were less active and sheltered more and also exhibited a decrease in ciliary bundles. These results suggest that there are sublethal effects of anthropogenic noise on fish behaviour and ciliary bundles, which may have direct implications on population health. Moreover, commonly used metrics such as stress hormones may not always offer the most relevant biomarker of the response to anthropogenic boat noise. L'effet du bruit sous l'eau sur les poissons suscite de plus en plus d'inquietudes en raison des niveaux croissants de bruit d'origine humaine. Nous avons realise des experiences sur la barbotte noire (Ameiurus melas), une espece montrant des specialisations auditives presente dans les Grands Lacs laurentiens, le lieu d'une importante circulation d'embarcations commerciales et recreatives. Nous avons verifie et compare la physiologie (concentration de base de cortisol), le comportement (activite, mise a l'abri) et la morphologie (touffes ciliaires de cellules ciliees) de barbottes noires en presence de bruit d'embarcation. A 140 dB re 1 [micro]Pa (-54,84 dB re 1 mx[s.sup.-2]), nous avons note des effets comportementaux clairs en ce qui concerne les niveaux d'activite et de mise a l'abri, malgre l'absence de stress morphologique ou physiologique evident. Apres des periodes d'exposition aigue courtes et longues a des niveaux de bruit plus eleves, mais toujours pertinents sur le plan environnemental, les barbottes noires etaient moins actives et s'abritaient plus, en plus de presenter une diminution des touffes ciliaires. Ces resultats donnent a penser que le bruit d'origine humaine a des effets subletaux sur le comportement des poissons et les touffes ciliaires, qui pourraient avoir des consequences directes sur la sante des populations. En outre, des parametres couramment utilises comme la concentration d'hormones de stress pourraient ne pas toujours etre les biomarqueurs les plus pertinents de la reaction au bruit d'embarcations. [Traduit par la Redaction], Introduction Anthropogenic noise is now common in aquatic ecosystems, although the effects this has on aquatic animals, particularly freshwater fishes, remains unclear (Slabbekoorn et al. 2010; Popper and Hawkins 2012). [...]

Byline: G. Islam, F. Abbas, M. Hafeez-ur-Rehman and M. Ashraf Keywords: Labeo rohita, heavy metals toxicity, water sources, vital organs, histo-pathological changes. INTRODUCTION Heavy metals are naturally found in aquatic [...]

Morphological and chemical features of fish otoliths are used to distinguish between populations and stocks. We hypothesized that these features can also be used to distinguish between fishes of different taxonomic groups common in and near the Santa Barbara Basin, including mesopelagic, pelagic, and demersal fish. Sagittal otoliths obtained from 905 fish representing six taxonomic groups were imaged, and 12 geometric and 59 elliptic Fourier morphometric features were extracted. A subset of 143 otoliths was also analyzed for Li, Na, Mg, K, Mn, Sr, and Ba. We used chemical composition in addition to morphology because the latter may be altered between otolith formation and analysis. Two sets of classifiers were made: one using only morphometric features and one using both morphometric and element features. Random forest analysis was generally superior to discriminant function analysis. Highest classification success, evaluated using cross-validation and otoliths of masked identity, was achieved with multiple feature types. The ten strongest discriminatory features of all available feature types were used in the final classification models. Our method is applicable to the classification of otoliths recovered from guts, feces, middens, and sediments as well to classify other biological objects. Des caracteristiques morphologiques et chimiques des otolites de poissons sont utilisees pour distinguer les populations et stocks. Nous avons postule que ces caracteristiques peuvent egalement etre utilisees pour distinguer des poissons de differents groupes taxonomiques repandus dans le bassin de Santa Barbara et a proximite, dont des poissons mesopelagiques, pelagiques et demersaux. L'imagerie d'otolites sagittaux obtenus de 905 poissons representant six groupes taxonomiques a ete realisee, et 12 caracteristiques geometriques et 59 caracteristiques morphometriques tirees de l'analyse elliptique de Fourier en ont ete extraites. Un sous-ensemble de 143 otolites a egalement ete analyse pour en determiner les concentrations de Li, Na, Mg, K, Mn, Sr et Ba. Nous avons utilise la composition chimique en plus de la morphologie parce que cette derniere pourrait avoir ete modifiee entre la formation des otolites et leur analyse. Deux ensembles de classificateurs ont ete etablis: un qui n'emploie que des caracteristiques morphometriques, et l'autre, reposant sur des caracteristiques tant morphometriques que chimiques. L'analyse des forets aleatoires etait generalement superieure a l'analyse de fonction discriminante. Le succes de classification le plus eleve, evalue en utilisant la validation croisee et des otolites dont l'identite etait masquee, a ete obtenu en utilisant plus d'un type de caracteristiques. Les dix caracteristiques discriminantes les plus fortes de tous les types de caracteristiques disponibles ont ete utilisees dans les modeles de classification finaux. Notre methode peut s'appliquer a la classification d'otolites recuperes des tubes digestifs, des feces, d'amoncellements et de sediments, ainsi qu'a la classification d'autres objets biologiques. [Traduit par la Redaction], Introduction Otoliths are aragonite and protein structures in the inner ears of teleost fish that function in hearing and balance (Popper et al. 2005). Otoliths are relatively resistant to alteration [...]

Strontium isotope ratios ([sup.87]Sr/[sup.86]Sr) in otoliths are a well-established tool to determine origins and movement patterns of fish. However, otolith extraction requires sacrificing fish, and when working with protected or endangered species, the use of nonlethal samples such as scales, spines, and fin rays is preferred. Unlike otoliths that are predominantly aragonite, these tissues are composed of biological apatite. Laser ablation multicollector inductively coupled plasma mass spectrometry (LA-MC-ICP-MS) analysis of biological apatite can induce significant interference on mass 87, causing inaccurate [sup.87]Sr/[sup.86]Sr measurements. To quantify this interference, we applied LA-MC-ICP-MS to three marine samples (white seabass (Atractoscion nobilis) otolith; green sturgeon (Acipenser medirostris) pectoral fin ray; salmon shark (Lamna ditropis) tooth), and freshwater walleye (Sander vitreus) otoliths, scales, and spines). Instrument conditions that maximize signal intensity resulted in elevated [sup.87]Sr/[sup.86]Sr isotope ratios in the bioapatite samples, related to a polyatomic interference ([sup.40]Ca[sup.31]P[sup.16]O, [sup.40]Ar[sup.31]P[sup.16]O). Retuning instrument conditions to reduce oxide levels removed this interference, resulting in accurate [sup.87]Sr/[sup.86]Sr ratios across all tissue samples. This method provides a novel, nonlethal alternative to otolith analysis to reconstruct fish life histories. Les rapports d'isotopes de strontium ([sup.87]Sr/[sup.86]Sr) dans les otolites constituent un outil bien etabli pour determiner les origines et motifs de deplacement des poissons. L'extraction d'otolites necessite toutefois de sacrifier les poissons, et quand il s'agit d'especes protegees ou en peril, il est preferable d'utiliser des echantillons non letaux comme des ecailles, epines ou rayons de nageoire. Contrairement aux otolites, qui sont principalement constitues d'aragonite, ces tissus sont faits d'apatite biologique. L'analyse par spectrometrie de masse a source a plasma inductif a collection d'ions multiples combinee a l'ablation par laser (LA-MC-ICP-MS) d'apatite biologique peut induire une interference significative sur la masse 87, produisant des mesures inexactes du [sup.87]Sr/[sup.86]Sr. Pour quantifier cette interference, nous avons applique l'analyse par LA-MC-ICP-MS a trois echantillons marins (otolite d'acoupa blanc (Atractoscion nobilis); rayon de nageoire pectorale d'esturgeon vert (Acipenser medirostris); dent de taupe du Pacifique (Lamna ditropis) et fi des otolites, ecailles et epines de dore jaune (Sander vitreus) d'eau douce). Les conditions instrumentales qui maximisent l'intensite des signaux produisaient des rapports [sup.87]Sr/[sup.86]Sr eleves dans les echantillons de bioapatite, associes a une interference polyatomique ([sup.40]Ca[sup.31]P[sup.16]O, [sup.40]Ar[sup.31]P[sup.16]O). L'ajustement des conditions instrumentales afin de reduire les niveaux d'oxydes a elimine cette interference, produisant des rapports [sup.87]Sr/[sup.86]Sr exacts pour tous les echantillons de tissus. Cette methode constitue une solution de rechange originale et non letale a l'analyse des otolites pour reconstituer le cycle biologique des poissons. [Traduit par la Redaction], Introduction Understanding the origins, movement patterns, and habitat changes of fish is a fundamental question in fish ecology. Measuring strontium isotope ratios ([sup.87]Sr/[sup.86]Sr) in otoliths using in situ laser ablation [...]

In a stable population, the adult lifetime reproductive value must be balanced against early life survival. Although delaying maturity may increase fecundity, it also reduces survival. Larger size at maturity therefore not only allows for higher fecundity, but requires it. Using simple arguments from life history, we derive a direct proportionality relationship between the adult lifetime reproductive value and weight at maturation and find that this relationship is consistent with empirical evidence from 28 stocks and species of bony fish from temperate-boreal environments. However, the expected proportionality falls off if mortality increases to include fishing. Furthermore, we find that the fecundity type (determinate or indeterminate) affects the predicted adult reproductive value, which is significantly (10-fold) higher for an indeterminate spawner than for a determinate spawner of the same weight. These differences may relate to trade-offs in the adult life history traits and (or) to seasonality in the spawning environment, with subsequent consequences for early life stage survivorship. Dans une population stable, la valeur reproductive sur la duree de vie adulte doit etre evaluee a la lumiere de la survie au debut de la vie. Bien que le fait de retarder la maturite puisse accroitre la fecondite, cela reduit egalement la survie. Une plus grande taille a la maturite permet non seulement une plus grande fecondite, elle la requiert. En utilisant des arguments simples touchant au cycle biologique, nous obtenons une relation de proportionnalite directe entre la valeur reproductive sur la duree de vie adulte et le poids a la maturation et constatons que cette relation concorde avec les preuves empiriques pour 28 stocks et especes de poissons osseux de milieux temperes-boreaux. Cependant, la proportionnalite attendue diminue si la mortalite augmente en y incluant la peche. Nous constatons en outre que le type de fecondite (determinee ou indeterminee) a une incidence sur la valeur reproductive des adultes prevue, qui est significativement plus elevee (10 fois plus grande) pour un geniteur indetermine que pour un geniteur determine de poids identique. Ces differences pourraient etre reliees a des compromis touchant a des caracteres du cycle biologique adulte ou au caractere saisonnier du milieu de frai, avec des consequences sur la survie aux premieres etapes du cycle biologique. [Traduit par la Redaction], Introduction Most fish species exhibit high annual fecundity, producing several thousands to millions of eggs per year, for which the expected survival from egg to maturity is very low. Early [...]

As climate change advances, coastal marine ecosystems are predicted to experience increasingly frequent and intense heatwaves. At the same time, already variable CO.sub.2 levels in coastal habitats will be exacerbated by ocean acidification. High temperature and elevated CO.sub.2 levels can be stressful to marine organisms, especially during critical early life stages. Here, we used a fully cross-factored experiment to test the effects of simulated heatwave conditions (+ 4 °C) and elevated CO.sub.2 (1000 [micro]atm) on the aerobic physiology and swimming performance of juvenile Australasian snapper, Chrysophrys auratus, an ecologically and economically important mesopredatory fish. Both elevated temperature and elevated CO.sub.2 increased resting metabolic rate of juvenile snapper, by 21-22% and 9-10%, respectively. By contrast, maximum metabolic rate was increased by elevated temperature (16-17%) and decreased by elevated CO.sub.2 (14-15%). The differential effects of elevated temperature and elevated CO.sub.2 on maximum metabolic rate resulted in aerobic scope being reduced only in the elevated CO.sub.2 treatment. Critical swimming speed also increased with elevated temperature and decreased with elevated CO.sub.2, matching the results for maximum metabolic rate. Periods of elevated CO.sub.2 already occur in the coastal habitats occupied by juvenile snapper, and these events will be exacerbated by ongoing ocean acidification. Our results show that elevated CO.sub.2 has a greater effect on metabolic rates and swimming performance than heatwave conditions for juvenile snapper, and could reduce their overall performance and potentially have negative consequences for population recruitment., Author(s): Shannon J. McMahon [sup.1], Darren M. Parsons [sup.2] [sup.3], Jennifer M. Donelson [sup.1], Steve M. J. Pether [sup.4], Philip L. Munday [sup.1] Author Affiliations: (1) 0000 0004 0474 1797, [...]

The accumulation of CO.sub.2 in the atmosphere and resulting ocean acidification represent a threat to marine ecosystems. While acid-base regulatory capacity is well developed in marine fish, allowing compensation of extra-cellular pH during short-term hypercapnia, the possible energetic costs of such regulation during long-term exposure remain to be established. In this study, juvenile European sea bass (Dicentrarchus labrax) were exposed from 2 days post-hatching to three different ocean acidification scenarios: control (present condition, [Formula omitted] = 520 [micro]atm, pH 7.9), moderate acidification ( [Formula omitted] = 950 [micro]atm, pH 7.7), and high acidification ( [Formula omitted] = 1490 [micro]atm, pH 7.5). After 1.5 years of exposure, fish aerobic metabolic capacities, as well as elements of their oxygen extraction and transport chain, were measured. Compared to control, [Formula omitted] treatments did not affect fish standard metabolic rate (SMR). However, the most severe acidification condition was associated with a significantly elevated maximum metabolic rate (MMR).This was supported by heavier gill system and higher blood haemoglobin concentration. A reduction of maximum cardiac frequency (f.sub.Hmax) during incremental warming of anaesthetized fish was also observed in both acidification scenarios. On the other hand, the critical oxygen level (O.sub.2crit), the minimum oxygen level required to sustain SMR, did not differ among groups. The increased MMR, associated with maintained SMR, suggests that acid-base compensatory processes, although not increasing maintenance costs, may affect components of bass homeostasis, resulting in new internal physico-chemical conditions. The possibility that these alterations influence metabolic pathways and physiological functions involved in fish aptitude to maximally transport oxygen is discussed., Author(s): Amélie Crespel [sup.1] , Katja Anttila [sup.3] , Pernelle Lelièvre [sup.1] , Patrick Quazuguel [sup.1] , Nicolas Le Bayon [sup.1] , José-Luis Zambonino-Infante [sup.1] , Denis Chabot [sup.4] , [...]