Taxonomic, morphometric and limnological assessment of the commercially important ichthyofauna of Sakhakot Stream, Malakand, Pakistan / Avaliação taxonômica, morfométrica e limnológica da ictiofauna comercialmente importante do Riacho Sakhakot, Malakand, Paquistão

The present study was conducted for the taxonomic, morphometric and limnological assessment of the commercially important ichthyofauna of Sakhakot Stream, Malakand, Pakistan. The study area was divided into three sites along the water course namely Dargai Stream, Sakhakot Stream and Shergarh Stream. Fish samples were collected randomly during January to August 2017 with the help of fish gears. A taxonomic key was designed for the collected fish specimens. Ten fish species were identified belonging to 3 orders and 4 families. Family Cyprinidae was the dominant family with seven representative species while families Siluridae, Nemacheilidae and Mastacembelidae were represented by one species each. Lower mean total length and standard length was recorded in Puntius conchonius (Hamilton, 1822) as 9.2 ± 0.6 cm and 7.3 ± 0.6 cm respectively, while highest mean total length and standard length was recorded in Mastacembelus armatus (Lacepede, 1800) as 28.1 ± 1.7 cm and 15.9 ± 2.4 cm respectively. Mean pH of the water ranged from 6.1 at Shergarh Stream in August to 8.7 at Sakhakot Stream in January. Average temperature range was recorded from 10.9 °C in January at Dargai Stream to 18.7 °C in August at Shergarh Stream. No statistically significant difference was found for temperature (p = 0.96) and pH (p = 0.14) in the three water streams. The present study will provide a baseline for the rearing and enhancement of wild stock of the commercially important ichthyofauna in the field of aquaculture and fisheries.

O presente estudo foi realizado para a avaliação taxonômica, morfométrica e limnológica da ictiofauna comercialmente importante do Riacho Sakhakot, Malakand, Paquistão. A área de estudo foi dividida em três locais ao longo do curso de água, nomeadamente Riacho Dargai, Riacho Sakhakot e Riacho Shergarh. As amostras de peixes foram coletadas aleatoriamente durante janeiro e agosto de 2017, com a ajuda de artes de peixes. Uma chave taxonômica foi projetada para os espécimes de peixes coletados. Foram identificadas dez espécies de peixes pertencentes a 3 ordens e 4 famílias. A família Cyprinidae foi a família dominante, com sete espécies representativas, enquanto as famílias Siluridae, Nemacheilidae e Mastacembelidae foram representadas por uma espécie cada. O comprimento total médio mais baixo e o comprimento padrão foram registrados em Puntius conchonius (Hamilton, 1822) como 9.2 ± 0.6 cm e 7.3 ± 0.6 cm, respectivamente, enquanto o comprimento total médio e o comprimento padrão mais altos foram registrados em Mastacembelus armatus (Lacepede, 1800) como 28.1 ± 1.7 cm e 15.9 ± 2.4 cm, respectivamente. O pH médio da água variou de 6.1 no Riacho Shergarh em agosto a 8.7 no Riacho Sakhakot em janeiro. A faixa de temperatura média foi registrada de 10.9 °C em janeiro no Riacho Dargai a 18.7 °C em agosto no Riacho Shergarh. Não foi encontrada diferença estatisticamente significativa para temperatura (p = 0,96) e pH (p = 0,14) nos três cursos de água. O presente estudo fornecerá uma linha de base para a criação e aprimoramento do estoque selvagem da ictiofauna comercialmente importante no campo da aquicultura e pesca.

Liver colour scoring index, carotenoids and lipid content assessment as a proxy for lumpfish (Cyclopterus lumpus L.) health and welfare condition.

Ensuring lumpfish health and welfare in salmon farms is vital to reduce the high mortality rates reported and to guarantee a high delousing efficiency. Recent observations of farmed lumpfish livers have shown colours ranging from pale (colours 1 and 2), through bright orange (colours 3 and 4), to dark reddish-brown (colours 5 and 6), some of which may be related to welfare condition. To characterize the status of lumpfish deployed in four Faroese salmon farms, several welfare indicators were assessed: a weight-length relationship, scoring of external physical damage, and after dissection, stomach content and liver colour scoring. Liver samples were weighed, stored and analysed for lipid content, lipid classes, total pigments, fatty acid profile and histopathology to explain the differences between the mentioned liver colours. Bright orange livers, liver colours 3 and 4, were related to increased levels of carotenoid pigments rather than levels of lipids and appear to reflect good fish welfare. However, dark reddish-brown colours, liver colours 5 and 6, were associated with very low levels of triacyl glycerides in the liver, indicating use of lipid reserves and poor welfare condition. Histopathology confirmed that the dark reddish-brown livers, liver colours 5 and 6, formed a distinct group. Thus, liver colour was shown to be a good welfare indicator and should be monitored in farms.

Evaluation of ATP bioluminescence-based methods for hygienic assessment in fish industry.

AIMS: To evaluate ATP bioluminescence-based hygiene monitoring systems under conditions relevant to fish processing environments. METHODS AND RESULTS: The ATP bioluminescence of fish fractions that are potentially present after insufficient cleaning of fish processing environments was determined. Different fractions and interfering substances representing the stages from slaughtering to smoking were prepared and measured using two different commercial systems (SystemSURE Plus and Clean-Trace). ATP bioluminescence was quenched by acidic liquid smoke and by sodium chloride even at concentrations as low as 0·9% NaCl. Large variations were observed between different types of trout homogenates: the ATP bioluminescence from raw belly fat homogenate was 100-1000 times lower than for trout blood. There were about a 1000-fold lower ATP bioluminescence in raw compared to heat-treated fractions from trout, with the exception of blood. The bioluminescence from Listeria monocytogenes was very low. Results from fish processing plants supported the laboratory findings. CONCLUSIONS: The output from ATP-monitoring instruments depends on the nature of fish soil present, as well as the presence of sodium chloride and low pH. This may lead to considerable under- or overestimation of the level of organic soil. SIGNIFICANCE AND IMPACT OF THE STUDY: ATP bioluminescence instruments are widely used by the fish industry for monitoring hygiene. The monitoring method will only give valuable information about the hygiene if critical limits are set after a validation period, distinguishing between areas with different types of soil and between different hygiene zones.

Salt and marine products in the Classic Maya economy from use-wear study of stone tools.

Microscopic study of the edges of Late to Terminal Classic Maya (AD 600-900) chert stone tools from the Paynes Creek Salt Works, Belize, indicates most tools were used for cutting fish or meat or working hide, which was unexpected, given the virtual absence of fish or other animal remains at this large salt-production complex. Use-wear study shows that a minority of stone tools have edge-wear from woodworking. Our study suggests that salting fish was a significant activity at the salt works, which corresponds to Roman, Chinese, and other East Asian civilizations, where salt and salted fish were critical components of food storage, trade, and state finance. Based on analogy with modern Maya salt producers at Sacapulas, Guatemala, we provide estimates of the amounts of salt and salted fish produced at the Paynes Creek Salt Works and the implications for the Classic Maya economy. Salt cakes and salted fish were preserved commodities that could be stored and traded in the marketplace.

Assessment of multiple stressors on the growth of larval green sturgeon Acipenser medirostris: implications for recruitment of early life-history stages.

Early developmental stages of fishes are particularly sensitive to changes in environmental variables that affect physiological processes such as metabolism and growth. Both temperature and food availability have significant effects on the growth and survival of larval and juvenile fishes. As climate change and anthropogenic disturbances influence sensitive rearing environments of fishes it is unlikely that they will experience changes in temperature or food availability in isolation. Therefore, it is critical that we determine the effects of each of these potential stressors on larval growth and development, as well as understand the additive, synergistic or antagonistic effects of both. We reared threatened green sturgeon Acipenser medirostris (initial age ca. 32 days post hatch) at four temperatures (11, 13, 16 and 19°C) and two food availability rates (100% and 40% of optimal) to assess the effects of these stressors and their interactions on larval growth. We compared the overall size (fork length, total length and mass), growth rates (cm day-1 and g day-1 ) and relative condition factor of these larval and juvenile fish at 3 week intervals for up to 12 weeks. Our results indicated that temperature and food availability both had significant effects on growth and condition and that there was a significant interaction between the two. Fish reared with limited food availability exhibited similar patterns in growth rates to those reared with elevated food rates, but the effects of temperature were greatly attenuated when fish were food-limited. Also, the effects of temperature on condition were reversed when fish were reared with restricted food, such that fish reared at 19°C exhibited the highest relative condition when fed optimally, but the lowest relative condition when food was limited. These data are critical for the development of relevant bioenergetics models, which are needed to link the survival of larval sturgeons with historic environmental regimes, pinpoint temperature ranges for optimal survival and help target future restoration sites that will be important for the recovery of sturgeon populations.

Organization of the Orexin/Hypocretin System in the Brain of Holostean Fishes: Assessment of Possible Relationships with Monoamines and Neuropeptide Y.

Holosteans form a small group of actinopterygian fishes considered the sister group of teleosts. Despite this proximity to the biggest group of vertebrates, relatively few studies have been conducted to investigate the organization of the central nervous system of this group of fishes. In this study, the neuroanatomical distribution of orexin/hypocretin-like immunoreactive (OX-ir) cell bodies and fibers was analyzed in the brain of 3 representative species of the 2 orders of extant holosteans, the spotted gar Lepisosteus oculatus, the Florida gar Lepisosteus platyrhincus, and the bowfin Amia calva. Antibodies against orexin-A (OXA) and orexin-B (OXB) were used, which labeled the same cells and fibers throughout the brain. In addition, double immunohistofluorescence was performed for the simultaneous detection of OXA and OXB with tyrosine hydroxylase, serotonin, and neuropeptide Y (NPY), in an attempt to localize the orexinergic structures precisely and study the possible interactions between these neuroactive substances. The pattern of distribution of OX-ir cells in the 3 species was largely similar, showing labeled cells in the preoptic area (POA), and the tuberal and retrotuberal hypothalamic regions, with only subtle differences between species in the density of labeled cells. OX-ir fibers were found in all main brain subdivisions of the 3 species, mostly in the ventral subpallial areas, POA, hypothalamus, posterior tubercle, thalamus, and mesencephalic tectum. Different densities of orexinergic fibers were observed in relation to catecholaminergic and serotoninergic cell groups, as well as an absence of colocalization between orexins and NPY in the same hypothalamic neurons. The comparison of these results with those obtained in other vertebrates highlights a constant pattern of distribution of this system of neurotransmission among different groups of actinopterygian fishes, especially in teleosts. Conserved features shared by all vertebrates studied were also observed, such as the presence of OX-ir cells in the basal hypothalamus, reflecting the preserved functions of these neuropeptides over the course of evolution.

From body scale ontogeny to species ontogeny: Histological and morphological assessment of the Late Devonian acanthodian Triazeugacanthus affinis from Miguasha, Canada.

Growth series of Palaeozoic fishes are rare because of the fragility of larval and juvenile specimens owing to their weak mineralisation and the scarcity of articulated specimens. This rarity makes it difficult to describe early vertebrate growth patterns and processes in extinct taxa. Indeed, only a few growth series of complete Palaeozoic fishes are available; however, they allow the growth of isolated elements to be described and individual growth from these isolated elements to be inferred. In addition, isolated and in situ scales are generally abundant and well-preserved, and bring information on (1) their morphology and structure relevant to phylogenetic relationships and (2) individual growth patterns and processes relative to species ontogeny. The Late Devonian acanthodian Triazeugacanthus affinis from the Miguasha Fossil-Lagerstätte preserves one of the best known fossilised ontogenies of early vertebrates because of the exceptional preservation, the large size range, and the abundance of complete specimens. Here, we present morphological, histological, and chemical data on scales from juvenile and adult specimens (scales not being formed in larvae). Histologically, Triazeugacanthus scales are composed of a basal layer of acellular bone housing Sharpey's fibers, a mid-layer of mesodentine, and a superficial layer of ganoine. Developmentally, scales grow first through concentric addition of mesodentine and bone around a central primordium and then through superposition of ganoine layers. Ontogenetically, scales form first in the region below the dorsal fin spine, then squamation spreads anteriorly and posteriorly, and on fin webs. Phylogenetically, Triazeugacanthus scales show similarities with acanthodians (e.g. "box-in-box" growth), chondrichthyans (e.g. squamation pattern), and actinopterygians (e.g. ganoine). Scale histology and growth are interpreted in the light of a new phylogenetic analysis of gnathostomes supporting acanthodians as stem chondrichthyans.

Some heavy metals in the muscle of Capoeta trutta: risk assessment for the consumers.

This study was carried out to detect the concentrations of some heavy metals (copper, iron, zinc, cadmium and chromium) in the muscle of Capoeta trutta (Heckel, 1843) and in their surrounding water in order to study the potential human risk of consumption. The relationship between the heavy metal load of fish and some of their biological aspects (weight, length and sex) was also examined. In addition, the accumulation factors of heavy metals in this species were determined. The concentrations of Cu, Fe, Zn, Cd and Cr in water and muscle samples were analysed using ICP. Cu, Zn and Fe were detected in all samples, but Cd and Cr were not found in detectable levels. The results showed that heavy metals accumulation in muscle of fish was higher than that in the water. It was found that the level of heavy metals in the muscle of fish showed differences according to weight, length and sex of fish.

Length-based assessment of coral reef fish populations in the main and northwestern Hawaiian islands.

The coral reef fish community of Hawaii is composed of hundreds of species, supports a multimillion dollar fishing and tourism industry, and is of great cultural importance to the local population. However, a major stock assessment of Hawaiian coral reef fish populations has not yet been conducted. Here we used the robust indicator variable "average length in the exploited phase of the population ([Formula: see text])", estimated from size composition data from commercial fisheries trip reports and fishery-independent diver surveys, to evaluate exploitation rates for 19 Hawaiian reef fishes. By and large, the average lengths obtained from diver surveys agreed well with those from commercial data. We used the estimated exploitation rates coupled with life history parameters synthesized from the literature to parameterize a numerical population model and generate stock sustainability metrics such as spawning potential ratios (SPR). We found good agreement between predicted average lengths in an unfished population (from our population model) and those observed from diver surveys in the largely unexploited Northwestern Hawaiian Islands. Of 19 exploited reef fish species assessed in the main Hawaiian Islands, 9 had SPRs close to or below the 30% overfishing threshold. In general, longer-lived species such as surgeonfishes, the redlip parrotfish (Scarus rubroviolaceus), and the gray snapper (Aprion virescens) had the lowest SPRs, while short-lived species such as goatfishes and jacks, as well as two invasive species (Lutjanus kasmira and Cephalopholis argus), had SPRs above the 30% threshold.

Hematological and morphometric blood value of four cultured species of economically important tropical foodfish

The use and validation of fish health monitoring tools have become increasingly evident due to aquaculture expansion. This study investigated the hematology and blood morphometrics of Piaractus mesopotamicus, Brycon orbignyanus, Oreochromis niloticus and Rhamdia quelen. The fish were kept for 30 days in 300-liter aquariums, after which they were anesthetized with benzocaine and blood was collected from caudal vessels. In comparison to other species, B. orbignyanus presented the highest hematocrit (Ht), RBC averages and Mean Corpuscular Volume (MCV) with a particular range of data. B. orbignyanus presented lower Ht, Hb, RBC averages and values, and Mean Corpuscular Hemoglobin Concentration (MCHC). Oreochromis niloticus presented lower Ht, Hb, RBC averages and values, and Mean Corpuscular Hemoglobin Concentration (MCHC). Rhamdia quelen and O. niloticus presented higher variation of White Blood Cells (WBC), neutrophils (Nf), lymphocytes (Lf), monocytes (Mf) and thrombocytes (Trb). Data of large axes (LA), minor axes (MA), surface (SF) and volume (VL) are in the same variance range. This study has demonstrated that hematological variances can occur between animals of different species as well as of the same species.

O uso e validação de ferramentas para monitorar o estado de saúde dos peixes está se tornando mais evidente, devido à expansão da aquicultura. Este estudo investigou a hematologia e a morfometria do sangue de Piaractus mesopotamicus, Brycon orbignyanus, Oreochromis niloticus e Rhamdia quelen. Os peixes foram mantidos por 30 dias em aquários de 300 litros, após esse período os peixes foram anestesiados com benzocaína e o sangue coletado por punção caudal. Em comparação com outras espécies B. orbignyanus apresentou maiores médias de hematócrito (Ht), eritrócitos (Eri) e volume corpuscular médio (VCM) com um determinado intervalo de dados. Oreochromis niloticus apresentou menor média e valor de Ht, Hb, eritrócitos e concentração de hemoglobina corpuscular média (CHCM). Rhamdia quelen e O. niloticus apresentaram maior variedade de leucócitos (Leu), neutrófilos (Nf), linfócitos (Lf), monócitos (Mf) e de trombócitos (Trb). Dados de eixos maiores (EMA), eixos menores (EME), superfície (SF) e volume (VL) estão no mesmo intervalo de variação. Este estudo demonstrou que as variações hematológicas não ocorrem somente entre os animais de diferentes espécies, mas também entre os indivíduos da mesma espécie.

Long-term (2002-2011) changes on Cetengraulis edentulus (Clupeiformes: Engraulidae) fisheries in Guanabara Bay, Brazil.

C. edentulus accounts for the major fishery resource in Guanabara Bay, but there are only few studies about its captures.This study analyzed the long term changes on C. edentulus catches in Guanabara Bay, focusing especially on temporal variation on capture effort, boat storage temperature, and fish price and size.We assessed the 2002-2011 database of fish landings at the pier of Rubi S.A., with records of year, month, total catch (kg), number of fish per kg, boat storage temperature (OC), and price per kg to boat owner (US$). Those variables differed among years and months (ANOVA; p<0.01) with strong yearXmonth interactions for all, probably related to C. edentulus reproductive and recruitment seasons and environmental conditions of Guanabara Bay. Generalized additive models revealed that high C. edenuldus catches were associated with few boat loadings of large-sized fishes, which were conserved in higher boat storage temperatures and attained high market prices. Our long-term study stressed that variations on C. edentulus fishery were related to changes on boat storage temperature, fish size, price paid per kg, and frequency of landings, and that these descriptors are correlated with C. edentulus ecological traits and high phytoplankton availability. Nevertheless, further studies should be performed to address whether less evident factors, such as the fluctuation of concurrent Sardinella brasiliensis stock, would explain the termporal dynamics of C. edentulous stocks in Guanabara Bay.

Long-term (2002-2011) changes on Cetengraulis edentulus (Clupeiformes: Engraulidae) fisheries in Guanabara Bay, Brazil / Variaciones a gran escala (2002-2011) de las pesquerías de Cetengraulis edentulus (Clupeiformes: Engraulidae) en la bahía de Guanabara, Brasil

C. edentulus accounts for the major fishery resource in Guanabara Bay, but there are only few studies about its captures.This study analyzed the long term changes on C. edentulus catches in Guanabara Bay, focusing especially on temporal variation on capture effort, boat storage temperature, and fish price and size.We assessed the 2002-2011 database of fish landings at the pier of Rubi S.A., with records of year, month, total catch (kg), number of fish per kg, boat storage temperature (oC), and price per kg to boat owner (US$). Those variables differed among years and months (ANOVA; p<0.01) with strong yearXmonth interactions for all, probably related to C. edentulus reproductive and recruitment seasons and environmental conditions of Guanabara Bay. Generalized additive models revealed that high C. edentulus catches were associated with few boat loadings of large-sized fishes, which were conserved in higher boat storage temperatures and attained high market prices. Our long-term study stressed that variations on C. edentulus fishery were related to changes on boat storage temperature, fish size, price paid per kg, and frequency of landings, and that these descriptors are correlated with C. edentulus ecological traits and high phytoplankton availability. Nevertheless, further studies should be performed to address whether less evident factors, such as the fluctuation of concurrent Sardinella brasiliensis stock, would explain the temporal dynamics of C. edentulus stocks in Guanabara Bay.

Cetengraulis edentulus se distribuye por todo el Atlántico Sur y es la especie más explotada comercialmente en la bahía de Guanabara, Brasil. Entre 2002-2011 se analizaron los desembarques pesqueros de la empresa Rubi S.A., las capturas totales (kg), número de peces por kg, temperatura de almacenamiento en la embarcación (°C) y el precio pagado por kg de C. edentulus al propietario de la embarcación (US$). Todas las variables difirieron entre años y meses (ANOVA, p<0.01), con interacciones años × meses significativas para todas, probablemente a causa de los períodos reproductivo y de reclutamiento de C. edentulus y a las condiciones ambientales de la bahía. Modelos aditivos generalizados indicaron que capturas más elevadas de C. edentulus estuvieron asociadas con un menor número de desembarques, pero de peces más grandes, los cuales fueron conservados a temperaturas más elevadas y obtuvieron precios más altos de mercado. Aunque los cambios en los descriptores estén relacionados con los atributos ecológicos de C. edentulus y la productividad del fitoplancton, se necesitan más estudios para investigar si otros factores, tales como la fluctuación de los stocks de Sardinella brasiliensis, pueden afectar la dinámica temporal de los stocks de C. edentulus en la bahía.

Are the most plastic species the most abundant ones? An assessment using a fish assemblage.

Few studies have evaluated phenotypic plasticity at the community level, considering, for example, plastic responses in an entire species assemblage. In addition, none of these studies have addressed the relationship between phenotypic plasticity and community structure. Within this context, here we assessed the magnitude of seasonal changes in digestive traits (seasonal flexibility), and of changes during short-term fasting (flexibility during fasting), occurring in an entire fish assemblage, comprising ten species, four trophic levels, and a 37-fold range in body mass. In addition, we analyzed the relationship between estimates of digestive flexibility and three basic assemblage structure attributes, i.e., species trophic position, body size, and relative abundance. We found that: (1) Seasonal digestive flexibility was not related with species trophic position or with body size; (2) Digestive flexibility during fasting tended to be inversely correlated with body size, as expected from scaling relationships; (3) Digestive flexibility, both seasonal and during fasting, was positively correlated with species relative abundance. In conclusion, the present study identified two trends in digestive flexibility in relation to assemblage structure, which represents an encouraging departure point in the search of general patterns in phenotypic plasticity at the local community scale.

Population structure and stock assessment of Hoplias malabaricus (Characiformes: Erythrinidae) caught by artisanal fishermen in river-reservoir transition area in Brazil.

Hoplias malabaricus is a viable economic alternative for artisanal fishermen who used to live on the banks of rivers that now are dammed in Brazil. In order to preserve the species' natural stock, the main objectives of this study were to obtain bio-ecological information on this species reproduction, feeding dynamics and the description of the extent of its exploitation in river-reservoir transition area in Brazil. This way, from January to December 2005, different fishery catches were made with gill nets by artisanal fishermen, and a total of 426 individual H. malabaricus were obtained and sampled. From each specimen, the following biometric and biological data were analyzed: standard length, total weight, stomach contents, reproductive data such as sex, weight and gonadal maturation stage; with these data we estimated sex ratio, reproduction period and feeding habits. To assess growth parameters and infer on the degree of exploitation, the standard length frequency data were analysed using the FISAT (ELEFAN I) computer program. Data revealed a sex ratio of 0.8:1 (M:F), that reproduction occurs all year around, being more intense during spring and summer; it also showed that H. malabaricus is piscivorous. The growth parameters and mortality were estimated at: L(infinity) = 35.18 cm, k = 0.32 year, longevity = 9.3 years, Z = 1.25 years, M = 0.63 year and F = 0.62 year. The weight-length relationship was: In Wt = -3.1663+2.7456 In Lp. The yield-per-recruit analysis produced the following values: E = 0.496, E(max) = 0.916, E0.1 = 0.701 and E0.5 = 0.378. Overall, our data suggest that the stock of H. malabaricus is not yet overfished in the studied area.

Population structure and stock assessment of Hoplias malabaricus (Characiformes: Erythrinidae) caught by artisanal fishermen in river-reservoir transition area in Brazil

Hoplias malabaricus is a viable economic alternative for artisanal fishermen who used to live on the banks of rivers that now are dammed in Brazil. In order to preserve the species’ natural stock, the main objectives of this study were to obtain bio-ecological information on this species reproduction, feeding dynamics and the description of the extent of its exploitation in river-reservoir transition area in Brazil. This way, from January to December 2005, different fishery catches were made with gill nets by artisanal fishermen, and a total of 426 individual H. malabaricus were obtained and sampled. From each specimen, the following biometric and biological data were analyzed: standard length, total weight, stomach contents, reproductive data such as sex, weight and gonadal maturation stage; with these data we estimated sex ratio, reproduction period and feeding habits. To assess growth parameters and infer on the degree of exploitation, the standard length frequency data were analysed using the FISAT (ELEFAN I) computer program. Data revealed a sex ratio of 0.8:1 (M:F), that reproduction occurs all year around, being more intense during spring and summer; it also showed that H. malabaricus is piscivorous. The growth parameters and mortality were estimated at: L∞=35.18cm, k=0.32 year, longevity=9.3 years, Z=1.25 years, M=0.63 year and F=0.62 year. The weight-length relationship was: ln Wt=-3.1663+2.7456 ln Lp. The yield-per-recruit analysis produced the following values: E=0.496, Emax=0.916, E0.1=0.701 and E0.5=0.378. Overall, our data suggest that the stock of H. malabaricus is not yet overfished in the studied area. Rev. Biol. Trop. 59 (1): 71-83. Epub 2011 March 01.

Hoplias malabaricus representa una alternativa económica viable para los pescadores artesanales que viven a la orilla de ríos que actualmente cuentan con represas en Brasil. El objeto del presente estudio fue evaluar la dinámica de la reproducción, alimentación, crecimiento y nivel de explotación de la especie nativa Hoplias malabaricus, capturada por pescadores artesanales en la zona de transición entre el río Paranapanema y el Embalse de Jurumirim. En 2005, los especimenes de H. malabaricus se obtuvieron utilizando redes agalleras de forma mensual y se registraron las siguientes características y datos biológicos de cada uno: longitud estándar, peso corporal, sexo, estadio reproductivo, peso de las gónadas y contenido estomacal. Estos datos fueron utilizados para estimar la proporción sexual, el período reproductivo y los hábitos alimenticios. Para evaluar los parámetros de crecimiento y el grado de explotación, los datos de frecuencia de la longitud estándar fueron analizados utilizando el software FISAT a través de la rutina ELEFAN I. Según los resultados obtenidos, la proporción sexual fue de 0.8:1 (macho:hembra); la reproducción fue observada durante todo el año, pero sobre todo en la primavera y el verano. El hábito alimentario fue piscívoro. Los parámetros de crecimiento y mortalidad fueron estimados en: L∞=35.18cm, k=0.32/año; longevidad= 9.3, Z=1.25/año, M=0.63/año y F=0.62/año. La relación longitud-peso fue: Wt=-3.1663+2.7456lnLp. El análisis de rendimiento por recluta estimó los siguientes valores: E=0.496, Emax=0.916, E0.1=0.701 y E0.5=0.378. Puede concluirse que la población de H. malabaricus en la región estudiada todavía no está siendo altamente explotada.

Assessment of condition in pejerrey Odontesthes bonariensis (Atheriniformes: Atherinopsidae) populations: which index works best?

The pejerrey Odontesthes bonariensis is the most important target species in temperate freshwater fisheries of Argentina, and assessment of condition has been a regular practice and common diagnostic tool. Most pejerrey fishery studies have used Fulton's (K) index, without testing whether underlying assumptions or requirements were met. We analyzed and contrasted the applicability of K, Kn and Wr indices to assess condition status in several pejerrey populations inhabiting Pampean lakes. Our results showed that whereas Wr and Kn displayed significant condition changes across length at some study lakes, Kn portrayed a small range of variation. We also noted that pejerrey maximum length and size structure strongly varied among populations probably due to the characteristics of trophic niche changes through lifespan, depending on lake limnological characteristics and zooplankton availability. We conclude that the K index should be disregarded in those cases where populations show allometric growth and size ranges strongly vary. In turn, the Kn index appears to be only appropriate for regular within population assessment, being difficult to apply when comparisons between populations are needed and when they exhibit different weight-length relationship slopes. Finally, the Wr index should be strongly preferred if the objective is to perform comparisons between pejerrey populations, particularly when population structure is not well known, stocking has been used for population recovery, lakes are strongly supported by limnological changes, data are limited to only one or few samplings and metaphoetesis is suspected in pejerrey populations.(AU)

O peixe-rei Odontesthes bonariensis é a espécie mais importante na pesca de água doce da região temperada da Argentina, e a avaliação de sua condição corpórea tem sido uma prática normal e uma ferramenta de diagnóstico bastante utilizada. Grande parte dos estudos sobre a pesca do peixe-rei utiliza o índice de Fulton (K), sem testar se seus pressupostos são atendidos. Nós analisamos e comparamos a aplicabilidade dos índices K, Kn e Wr para a avaliação do fator de condição em várias populações de peixe-rei em lagos dos Pampas. Nossos resultados mostram que, enquanto o Wr e o Kn dependeram significativamente do comprimento corporal em alguns lagos, o Kn apresentou uma pequena amplitude de variação. Foi também notado que o comprimento máximo e a estrutura de tamanho variaram fortemente entre populações, provavelmente devido às mudanças ontogenéticas no nicho trófico, dependendo das características limnológicas e da disponibilidade de zooplâncton. Concluímos que o índice K deve ser desconsiderado nos casos em que as populações apresentam variações alométricas marcantes no crescimento e na amplitude de tamanhos. O índice Kn parece ser apropriado apenas para avaliações de uma única população, não sendo apropriado para comparações entre populações quando elas exibem diferentes inclinações na relação peso-comprimento. Finalmente, o índice Wr é recomendado se o objetivo for fazer comparações entre populações de peixe-rei, particularmente quando a estrutura populacional não é bem conhecida, a estocagem tenha sido usada para a recuperação populacional, os lagos apresentam grandes variações limnológicas, os dados se limitam a uma ou poucas amostras e suspeita-se da ocorrência de mudanças ontogenéticas na dieta.(AU)

Fish-induced keriorrhea.

Many deep-sea fishes store large amounts of wax esters in their body for buoyancy control. Some of them are frequently caught as by-catch of tuna and other fishes. The most noteworthy ones include escolar and oilfish. The accumulation of the indigestible wax esters in the rectum through consumption of these fish engenders discharges or leakage per rectum as orange or brownish green oil, but without noticeable loss of water. This physiological response is called keriorrhea, which is variously described as "oily diarrhea," "oily orange diarrhea," or "orange oily leakage" by the mass media and bloggers on the internet. Outbreaks of keriorrhea have been repeatedly reported across continents. Additional symptoms including nausea, vomiting, abdominal cramps, and diarrhea were complained by the victims. They are probably due to anxiety or panic when suffering from keriorrhea. Escolar and oilfish are banned from import and sale in Italy, Japan, and South Korea. Rapid detection of the two fishes is imperative to ensure proper labeling and safeguarding of the public before and after any keriorrhea outbreak.

Assessment of the dorsal fin spine for chimaeroid (Holocephali: Chimaeriformes) age estimation.

Previous attempts to age chimaeroids have not rigorously tested assumptions of dorsal fin spine growth dynamics. Here, novel imaging and data-analysis techniques revealed that the dorsal fin spine of the spotted ratfish Hydrolagus colliei is an unreliable structure for age estimation. Variation among individuals in the relationship between spine width and distance from the spine tip indicated that the technique of transverse sectioning may impart imprecision and bias to age estimates. The number of growth-band pairs observed by light microscopy in the inner dentine layer was not a good predictor of body size. Mineral density gradients, indicative of growth zones, were absent in the dorsal fin spine of H. colliei, decreasing the likelihood that the bands observed by light microscopy represent a record of growth with consistent periodicity. These results indicate that the hypothesis of aseasonal growth remains plausible and it should not be assumed that chimaeroid age is quantifiable by standard techniques.

A comparison of marine protected areas and alternative approaches to coral-reef management.

Marine protected areas (MPAs) have been widely adopted as the leading tool for coral-reef conservation, but resource users seldom accept them , and many have failed to produce tangible conservation benefits [3]. Few studies have objectively and simultaneously examined the types of MPAs that are most effective in conserving reef resources and the socioeconomic factors responsible for effective conservation [4-6]. We simultaneously explored measures of reef and socioeconomic conservation success at four national parks, four comanaged reserves, and three traditionally managed areas in Indonesia and Papua New Guinea. Underwater visual censuses of key ecological indicators [7, 8] revealed that the average size and biomass of fishes were higher in all areas under traditional management and at one comanaged reserve when compared to nearby unmanaged areas. Socioeconomic assessments [6, 9, 10] revealed that this "effective conservation" was positively related to compliance, visibility of the reserve, and length of time the management had been in place but negatively related to market integration, wealth, and village population size. We suggest that in cases where the resources for enforcement are lacking, management regimes that are designed to meet community goals can achieve greater compliance and subsequent conservation success than regimes designed primarily for biodiversity conservation.

Do scientists and fishermen collect the same size fish? Possible implications for exposure assessment.

Recreational and subsistence fishing plays a major role in the lives of many people, although most Americans obtain their fish from supermarkets or other commercial sources. Fish consumption has generally increased in recent years, largely because of the nutritional benefits. Recent concerns about contaminants in fish have prompted federal and state agencies to analyze fish (especially freshwater fish targeted by recreational anglers) for contaminants, such as mercury and polychlorinated biphenyls (PCBs), and to issue fish consumption advisories to help reduce the public health risks, where warranted. Scientists engaged in environmental sampling collect fish by a variety of means, and analyze the contaminants in those fish. Risk assessors use these levels as the basis for their advisories. Two assumptions of this methodology are that scientists collect the same size (and types) of fish that fishermen catch, and that, for some contaminants (such as methylmercury and PCBs), levels increase with the size and age of the fish. While many studies demonstrate a positive relationship between size and mercury levels in a wide range of different species of fish, the assumption that scientists collect the same size fish as fishermen has not been examined. The assumption that scientists collect the same size fish as those caught (and eaten) by recreationalists or subsistence fishermen is extremely important because contaminant levels are different in different size fish. In this article, we test the null hypothesis that there are no differences in the sizes of fish collected by Aleut fishermen, scientists (including divers), and commercial trawlers in the Bering Sea from Adak to Kiska. Aleut fishermen caught fish using rod-and-reel (fishing rods, hook, and fresh bait) from boats, as they would in their Aleutian villages. The scientists collected fish using rod-and-reel, as well as by scuba divers using spears up to 90 ft depths. A fisheries biologist collected fish from a research/commercial trawler operated under charter to the National Oceanographic and Atmospheric Administration (NOAA). The fish selected for sampling, including those caught commercially in the Bering Sea, represented different trophic levels, and are species regularly caught by Aleuts while fishing near their villages. Not all fish were caught by all three groups. There were no significant differences in length and weight for five species of fish caught by Aleuts, scientists, and fisheries trawls, and for an additional 3 species caught only by the Aleut and scientist teams. There were small, but significant, differences in the sizes of rock greenling (Hexagrammos lagocephalus) and red Irish lord (Hemilepidotus hemilepidotus) caught by the scientist and Aleut fishermen. No scientists caught rock greenling using poles; those speared by the divers were significantly smaller than those caught by the Aleuts. Further, there were no differences in the percent of males in the samples as a function of fishing method or type of fishermen, except for rockfish and red Irish lord. These data suggest that if scientists collect fish in the same manner as subsistence fishermen (in this case, using fishing rods from boats), they can collect the same-sized fish. The implications for exposure and risk assessment are that scientists should either engage subsistence and recreational fishermen to collect fish for analysis, or mimic their fishing methods to ensure that the fish collected are similar in size and weight to those being caught and consumed by these groups. Further, total length, standard length, and weight were highly correlated for all species of fish, suggesting that risk assessors could rely on recreational and commercial fishermen to measure total lengths for the purpose of correlating mercury levels with known size/mercury level relationships. Our data generally demonstrate that the scientists and trawlers can collect the same size fish as those caught by Aleuts, making contaminant analysis, and subsequent contaminant analysis, representative of the risks to fish consumers.