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The Pacific sardine, (Sardinops sagax), is a small, coastal pelagic species in the family Clupeidae. Sardine are ecologically important forage for many animals, and have historically supported a large commercial fishery. To expand on previous evolutionary genetic studies of population structure and to test if population structure is present in Pacific sardine was reflective of long-term processes, 434 individuals were examined ranging from Vancouver Island, British Columbia to Bahia Magdalena, Baja California, and from the Gulf of California. A 1062 bp fragment of the cytochrome b gene yielded small but significant fixation estimates of [[PHI].sub.ST] (0.01136, p = 0.032). Concordantly low fixation was observed for two [[PHI].sub.CT] groupings (0.00435, p = 0.128 and 0.00923, p = 0.021). These data support the null hypothesis of an absence of genetic structure in the Pacific sardine., Analysis of population structure is important to the study of species and to the field of evolutionary biology. Molecular analysis of populations in relation to hypothesized barriers to gene flow [...]

Fish is an important resource in Malawi as a source of food for the majority as it provides affordable source of dietary animal protein as well as income. A number of fish species in the Malawi water bodies have their population dwindling. One of the species under serious threat of extinction is the Opsaridium microlepis - a potamodromous fish species that migrate to the rivers during its spawning period and its management seems a nightmare. A number of studies reveal contrasting results on genetic makeup and morphological aspect of this fish species. With changes in the ecosystems of the rivers connecting Lake Malawi, coupled with absence of strong management measures in the major rivers adjoining the lake, problems have arisen in the conservation of potamodromous fish species. This necessitated the present study to investigate if the morphological features of stocks of O. microlepis are the same or not and if they have changed to adapt to changes in the ecosystems. One hundred and eleven O. microlepis fish samples were collected from Linthipe River (48), Bua River (59) and North Rumphi River (4) monthly from March to August 2020 using trawled and static gillnets. Twenty-four morphometric characteristics were measured to determine if any morphological differences existed among the fish samples from the three rivers. Principal component analysis (PCA) was used to compare morphology of the fish. Results of the study showed no significant morphological differences among stocks from the three rivers, implying that O. microlepis in these rivers belong to same stock morphologically. The study reveals that the species do not differ morphologically even though they migrate to different rivers for breeding. The study further notes that numerous activities taking place along the tributary rivers (as observed during the study) such as modification of fishing gears as well as fishing methods and the deterioration of the spawning grounds due to siltation from soil erosion caused by deforestation and agriculture, are putting the potamodromous fish species such as O. microlepis under serious threat. The study recommends that the populations of O. microlepis from the rivers can be managed equally since they are morphologically similar. Adopting uniform catchment management and sustainable exploitation of O. microlepis (such as regulations on mesh sizes and fishing methods, closing the rivers from fishing activities during spawning period, river bank and catchment management and restoration) with the aim of conserving the stocks from further overexploitation in these rivers is recommended so that the communities and the people at large continue to utilize the resource sustainably and at the same time, sustaining their livelihood. Key words: Potamodromous, Linthipe River, Bua River, North Rumphi River, principal component analysis, INTRODUCTION Fish morphometrics are studied extensively in fisheries science [1]. Variations in fish morphology and body shape have often been described subjectively and qualitatively [2]. Such kind of morphological variations [...]

Organisms increase in size over time (age) due to excess assimilation over metabolic (respiration) energy demands. Most organisms reach a maximum size with increasing age as gain and loss balance. The von Bertalanffy length-at-age relationship, which is commonly used in fishery assessment calculations, imposes such a maximum size. However, some fished species, such as ocean quahogs, Arctica islandica, are long lived and continue to grow at old age. The Tanaka age-at-length relationship has continued growth at old age, but is rarely used in stock assessment models. A modified form of the von Bertalanffy model is presented, which mimics the continued growth at old age of the Tanaka model by allowing the growth parameter (K) to decline with age. This form is suitable for inclusion in stock assessment models based on von Bertalanffy. The proposed model matches Tanaka curves with precision appropriate for the scatter of data used to fit the curves. The observations of ocean quahog length at age and growth rate from New Jersey and Georges Bank demonstrate the ability of the modified von Bertalanffy relationship to represent continued growth at old age for this fished species. Simulated data generated with continued growth at old age were fit with the Stock Synthesis model (SS3). Results comparing traditional and modified growth relationships showed that the original von Bertalanffy model can reasonably approximate modest nonasymptotic growth as long as the number of observations is sufficient to constrain the parameter values. KEY WORDS: Arctica islandica, shellfish fisheries, length-at-age, growth model, ocean quahog, Bertalanffy growth, INTRODUCTION Most organisms increase in size over time in response to excess assimilated energy above metabolic demands, often termed scope for growth (Barilleet al. 1997, Munroeet al. 2013, Sanders et [...]

Animal personality can be defined as behavioral individual consistency across contexts and time, and sociability may facilitate it. Boldness and exploration can be considered as social conflictive behaviors and in lizards, social scent can either diminish or promote social conflicts. We studied boldness and exploration in Liolaemus albiceps Lobo and Laurent, 1995 and Liolaemus coeruleus Cei and Ortiz, 1983, and tested whether Liolaemus albiceps, a lesser aggressive species, presents higher individual consistency in a socially nonconflictive behavior, such as escape (boldness). We also expect Liolaemus coeruleus, a more aggressive species, to present higher individual consistency in exploration, which is socially more conflictive behavior. We exposed lizards to their own conspecifics and control scent treatments. We calculated the repeatability for boldness and exploration, analyzed their correlation, and tested for behavioral plasticity. Boldness and exploration were repeatable in Liolaemus albiceps at species level, with females showing highly repeatable boldness, and males, highly repeatable exploration. Liolaemus coeruleus exhibited no significant repeatability for either behavior. There was no correlation between these two behaviors, and both species showed plasticity. Liolaemus albiceps individuals were bolder and explored less under conspecific scents. Liolaemus coeruleus individuals explored less in presence of their own scents than novelty scents, and presented interindividual variation in plasticity. A peaceful lifestyle may favor behavioral consistency within individuals, whereas a more aggressive lifestyle may constrain within and among individual consistency in a chemical communication context. However, individual differences in plasticity could counterbalance this constraint. Key words: behavioral types, plasticity, repeatability, Squamata, Introduction Animal personality can be defined as those consistent individual differences in the same behavior across distinct contexts, situations, and times (Dall et al. 2004; Dingemanse et al. 2010; Reale [...]

The intestinal tract of herbivorous arthropods provides a microhabitat for a group of protistan and fungal endosymbionts known as trichomycetes. Many hosts are the aquatic immature stages of insects. One understudied group is mosquito larvae with only six trichomycete species reported from the mosquito gut, but Smittium culicis Manier and Zancudomyces culisetae Y. Wang, Tretter, Lichtw. & M.M. White are globally distributed and common in these insects. Mosquitoes are mostly found in standing freshwater habitats, but there are species that are found in brackish water pools common in salt marshes. No trichomycetes are reported from salt marsh mosquitoes. A new species, Legerioides culicicola, is described from mosquito larvae from freshwater sources in Nova Scotia (NS) and Prince Edward Island (PEI), Canada, and Smittium gronthidium Strongman & M.M. White is reported for the first time in this host. Smittium culicis is reported from salt marsh mosquitoes from collections in the same provinces in Eastern Canada. Information on the prevalence of mosquito trichomycetes is presented for sites in NS and PEI. Key words: insect gut fungi, Kickxellomycotina, lentic habitats, salt marsh, Smittium culicis Le tractus intestinal des arthropodes herbivores constitue un microhabitat pour un groupe d'endosymbiontes protistes et fongiques connus sous le nom de trichomycetes. De nombreux hotes sont les stades immatures aquatiques d'insectes. Les larves de moustiques constituent un groupe peu etudie, seules six especes de trichomycetes ayant ete signalees dans l'intestin des moustiques, mais Smittium culicis Manier et Zancudomyces culisetae Y. Wang, Tretter, Lichtw. & M.M. White sont distribuees dans le monde entier et sont communes chez ces insectes. Les moustiques se trouvent principalement dans des habitats d'eau douce stagnante, mais certaines especes se trouvent dans des bassins d'eau saumatre communs dans les marais sales. Aucun trichomycete n'a ete signale chez les moustiques des marais sales. Une nouvelle espece, Legerioides culicicola, est decrite a partir de larves de moustiques provenant de sources d'eau douce en Nouvelle-Ecosse (N.-E.) et a l'lle-du-Prince-Edouard (l'I.-P.-E.), au Canada, et Smittium gronthidium Strongman & M.M. White est signale pour la premiere fois dans cet hote. Smittium culicis est signale sur des moustiques de marais sales provenant de collections dans les memes provinces de l'Est du Canada. Des informations sur la prevalence des trichomycetes des moustiques sont presentees pour des sites en N.-E. et a 1T.-P.-E. [Traduit par la Redaction] Mots-cles : champignons de l'intestin des insectes, Kickxellomycotina, habitats lentiques, marais sales, Smittium culicis, Introduction Trichomycetes are composed of fungal and protistan species that are common, obligate colonizers of the intestinal tract of freshwater, marine, and some terrestrial arthropods (Lichtwardt 1986; Lichtwardt et al. [...]

Bay scallops (Argopecten irradiuns conemtricus Say. 1822) exhibit a strong association with seagrass habitat from the time of larval settlement, but alternative habitats, such as macroalgae species, may also serve as important habitats for this species. The association of Florida bay scallops with the percent cover of observed seagrass, macroalgal species, and several substrate types (e.g., mud, shell, and rocks) was examined to determine whether a variety of seagrass and macroalgal species significantly influences the abundance of bay scallops in Florida. Sampling occurred at eight study sites along the Gulf coast of Florida, from Tampa Bay in the south to St. Andrew Bay in the north. SCUBA divers used a point-intercept approach along a transect to assess habitat type and percent cover, in addition to recording bay scallop abundance. Generalized additive models for location, scale, and shape were used to model bay scallop abundance as a function of habitat type. Across all sites, bay scallop abundance was positively correlated with percent cover of seagrass and negatively correlated with bare substrate, such as mud and sand. Five out of the 13 habitat types observed in association with bay scallops in this study were significant factors in models of bay scallop abundance including Acetabularia spp. (J.V. Lamouroux. 1812), Cmderpa spp. (J.V. Lamouroux, 1809), Gracilaria spp. (Greville, 1830), Syringadium filiforme (Kiitz, 1860), and Thalassia testudinum (Koenig. 1805). The two most important habitat variables were T. testudinum and Gracilaria spp., and there was an observed threshold response of bay scallop abundance to these habitat variables at low to medium percent cover. This is the first study to identify the importance of both seagrass and several macroalgal species for Florida bay scallops and suggests that bay scallop restoration efforts may benefit from restoring seagrass and macroalgae. KEY WORDS: Argopecten irradians concentricus, bay scallop, Florida, habitat, macroalgae, Thalassia. seagrass, GAMLSS, INTRODUCTION Bay scallops (Argopecten irradians Say. 1822) are found in coastal, benthic habitats ranging from Cape Cod, Massachusetts to Laguna Madre, Texas (Fay et al. 1983). Commercial bay scallop fisheries [...]

The starvation tolerance of the moonsnail Laguncula pulchella was examined under nonfeeding conditions in the laboratory using individuals at the early stages of development, which comprised subadults ( KEY WORDS: Laguncula pulchella, naticid gastropod, nonfeeding experiment, early survival, carnivore, INTRODUCTION Starvation can influence the feeding behavior and growth of marine molluscs. For example, the scavenging gastropod Nassarius fraterculus tends to eat conspecifics as starvation progresses (Zhang & Goshima 2013). [...]

Killer whales (Orcinus orca) produce a variety of acoustic signal types used for communication: clicks, whistles, and pulsed calls. Discrete pulsed calls are highly stereotyped, repetitive, and unique to individual pods found around the world. Discriminating amongst pod specific calls can help determine population structure in killer whales and is used to track pod movements around oceans. Killer whale presence in the Canadian Arctic has increased substantially, but we have limited understanding of their ecology, movements, and stock identity. Two autonomous passive acoustic monitoring (PAM) hydrophones were deployed in the waters of Eclipse Sound and Milne Inlet, in northern Baffin Island, Nunavut, Canada, in August and September 2017. Eleven killer whale pulsed call types, three multiphonic and eight monophonic, are proposed and described using manual whistle contour extraction and feature normalization. Automated detection of echolocation clicks between 20 and 48 kHz demonstrated little to no overlap between killer whale calls and echolocation presumed to be narwhal, which suggests that narwhal remain audibly inconspicuous when killer whales are present. Describing the acoustic repertoire of killer whales seasonally present in the Canadian Arctic will aid in understanding their acoustic behaviour, seasonal movements, and ecological impacts. The calls described here provide a basis for future acoustic comparisons across the North Atlantic and aid in characterizing killer whale demographics and ecology, particularly for pods making seasonal incursions into Arctic waters. Key words: killer whale; Orcinus orca; bioacoustics; Canadian Arctic; passive acoustic monitoring L'epaulard (Orcinus orca) produit divers types de vocalises acoustiques servant a communiquer : des clics, des sifflements et des signaux pulses. Les signaux pulses discrets sont grandement stereotypes, repetitifs et uniques a chacun des bancs d'epaulards repartis de par le monde. La discrimination entre les vocalises propres a chaque banc peut aider a determiner la structure de la population d'epaulards et permet de suivre les mouvements des bancs dans les oceans. La presence d'epaulards dans l'Arctique canadien s'est accrue considerablement, mais nous avons une comprehension restreinte de leur ecologie, de leurs mouvements et de l'identite du stock. Deux hydrophones autonomes de surveillance acoustique passive (SAP) ont ete deployes dans les eaux du detroit d'Eclipse et de l'inlet Milne, dans le nord de l'lle de Baffin, au Nunavut, Canada, en aout et en septembre 2017. Onze types de signaux pulses produits par des epaulards, dont trois etaient multiphoniques et huit, monophoniques, sont proposes et decrits a l'aide de l'extraction manuelle des contours de sifflements et de la normalisation des caracteristiques. La detection automatisee des clics d'echolocalisation se situant entre 20 et 48 kHz a permis de constater peu ou pas de chevauchements entre les vocalises d'epaulards et l'echolocalisation presumee des narvals, ce qui suggere que les narvals se font a peine audibles en presence d'epaulards. La description du repertoire acoustique des epaulards presents dans l'Arctique canadien de maniere saisonniere favorisera la comprehension de leur comportement acoustique, de leurs mouvements saisonniers et des impacts ecologiques. Les vocalises decrites dans cet article pourront servir de fondement aux futures comparaisons acoustiques dans l'Atlantique Nord et aideront a caracteriser la demographie et l'ecologie des epaulards, particulierement en ce qui a trait aux bancs faisant des incursions saisonnieres dans les eaux de l'Arctique. Mots cles : epaulard; Orcinus orca; bioacoustique; Arctique canadien; surveillance acoustique passive, Traduit pour la revue Arctic par Nicole Giguere. INTRODUCTION Killer whales (Orcinus orca) have a cosmopolitan distribution, with pods organized into ecologically distinct groupings, or ecotypes. Ecotypes are defined by [...]