Desarrollo de un indicador de talla para poblaciones de peces

Monitoring temporal and/or spatial variations in fish size-at-age data can often provide fisheries managers with important information about the status of fish stocks and therefore help them identify necessary changes in management policies. However, due to the multivariate nature of size-at-age data, commonly used single-age-based approaches ignore covariance between sizes of different age groups. Different results may therefore be derived when evaluating temporal variations using different age groups for the comparison. The possibility of atypical errors in size-at-age data due to ageing and measurement errors further complicates the comparison. We propose a two-step approach for developing an indicator for monitoring temporal and/or spatial variation in size-at-age data. A robust approach, minimum volume ellipsoid analysis, is used to identify possible outliers in size-at-age data. Then a weighted principal component analysis is applied to the data with the identified outliers down-weighted. An indicator is defined from the resultant principal components for monitoring temporal/spatial variations in size-at-age data. We illustrate the proposed approach with size-at-age data for cod (Gadus morhua) in the northwest Atlantic, NAFO subdivision 3Ps. The overall size-at-age indicator identified shows that the pre-1980 year classes tend to have a much higher size-at-age than the post-1980 year classes.El seguimiento de las variaciones temporales y/o espaciales de datos de talla por edad en peces puede, a menudo, aportar información a los gestores de pesquerías sobre el estado de explotación de los stocks de peces y ayudarles a identificar los cambios necesarios en políticas de gestión. Sin embargo, debido a la naturaleza multivariante de los datos de talla por edad, las aproximaciones tradicionalmente empleadas, basadas en el análisis de una sola clase de edad, ignoran la covarianza entre tallas de distintos grupos de edad, lo que puede generar distintos resultados cuando se analizan variaciones temporales mediante la comparación de distintos grupos de edad. La posible existencia de errores atípicos en datos de talla por edad, debidos a errores de atribución de edad o errores de medida, puede complicar más la comparación. Proponemos una aproximación en dos etapas para el desarrollo de un indicador para el seguimiento de variaciones temporales o espaciales en datos de talla por edad. Una aproximación robusta, conocida como análisis de elipsoide de volumen mínimo, nos permite identificar los posibles valores aberrantes en datos de talla por edad, y a continuación aplicamos el análisis ponderado de componentes principales a los datos con los valores aberrantes debidamente ponderados. Los componentes principales resultantes permiten definir el indicador para el seguimiento de las variaciones espacio-temporales en datos de talla por edad. Ilustramos la aproximación propuesta con datos por edad de bacalao (Gadus morhua) in el Atlántico noroccidental, correspondiente a la subdivisión 3Ps de la NAFO. El indicador general de talla por edad obtenido muestra que las clases de edad anteriores a 1980 tienden a tener una talla por edad mucho mayor que las clases de edad posteriores a 1980

Catch Pattern for Antarctic krill (Euphausia superba) of Different Commercial Trawls in Similar Times and Overlapping Fishing Grounds

Antarctic krill (Euphausia superba) is harvested using different design midwater trawls. Knowing the selective properties between trawls is crucial information for the management of the krill resources. This study compared the catch patterns between different commercial krill trawls at similar times and overlapping fishing grounds based on scientific data collected by scientific observers onboard commercial trawlers Long Teng (LT) and Fu Rong Hai (FRH). The results showed significant differences in the length-dependent catch densities and cumulative catch densities of krill between the two trawls. The krill length range in catches from LT's trawl was wider than that of FRH's trawl. Furthermore, the catch would consist of a larger proportion of smaller krill in the LT's trawl. The LT's trawl caught significantly higher proportions of krill below 38 mm than FRH's trawl. Even, the LT's trawl caught substantial numbers of kril

Análisis comparativo de la distribución en profundidad de diecisiete especies de grandes pelágicos, capturados en una pesquería de palangre en el océano Pacífico centro-oriental

The objective of this study was to estimate depth distribution of pelagic species captured in a longline fishery and to evaluate the difference in depth distribution among species. We estimated depth distribution for 17 frequently captured species based on a Chinese longline fishing trip targeting bigeye tuna (Thunnus obesus) in the central-eastern Pacific Ocean in February-November 2006. The depth distributions of 13 bycatch species were significantly different from that of bigeye tuna. Although most of the bycatch species were found to be distributed in water depths shallower than bigeye tuna (i.e. increasing hook depths can decrease catch rates of these species), the rates of catch rates declined with increasing hook depths may be different. The depth distributions were found to be not significantly different between genders for 7 species. There was no significant correlation between fish sizes and capture depths. The information derived from this study can play an important role in reducing bycatch in pelagic tuna longline fisheries in the central-eastern Pacific Ocean.El objetivo de este estudio ha sido estimar la distribución en profundidad de especies pelágicas capturadas en una pesquería de palangre y evaluar la diferencia en la distribución en profundidad entre las especies. Se estimó la distribución en profundidad para 17 especies capturadas frecuentemente, sobre la base de los datos obtenidos en una marea de una pesquería de palangre china dirigida al patudo (Thunnus obesus) en el océano Pacífico centro-oriental, durante febrero-noviembre 2006. Las distribuciones en profundidad de 13 especies no objetivo de la pesquería fueron significativamente diferentes de la del patudo. Aunque la mayoría de estas 13 especies se encontraron a menor profundidad que el patudo, la medida en la que la captura acompañante disminuye puede ser diferente al situar los anzuelos a mayor profundidad. En 7 de las especies no se encontraron diferencias significativas entre sexos en relación a la distribución en profundidad. No hubo correlación significativa entre los tamaños de los peces y las profundidades de captura. La información derivada de este estudio puede jugar un rol importante en la reducción de la captura acompañante de pesquerías pelágicas con palangre dirigidas a captura de atunes en el océano Pacífico centro-oriental

mRNA/microRNA Profile at the Metamorphic Stage of Olive Flounder (Paralichthys olivaceus)

Flatfish is famous for the asymmetric transformation during metamorphosis. The molecular mechanism behind the asymmetric development has been speculated over a century and is still not well understood. To date, none of the metamorphosis-related genes has been identified in flatfish. As the first step to screen metamorphosis-related gene, we constructed a whole-body cDNA library and a whole-body miRNA library in this study and identified 1051 unique ESTs, 23 unique miRNAs, and 4 snoRNAs in premetamorphosing and prometamorphosing Paralichthys olivaceus. 1005 of the ESTs were novel, suggesting that there was a special gene expression profile at metamorphic stage. Four miRNAs (pol-miR-20c, pol-miR-23c, pol-miR-130d, and pol-miR-181e) were novel to P. olivaceus; they were characterized as highly preserved homologies of published miRNAs but with at least one nucleotide differed. Representative 24 mRNAs and 23 miRNAs were quantified during metamorphosis of P. olivaceus by using quantitative RT PCR or stem-loop qRT PCR. Our results showed that 20 of mRNAs might be associated with early metamorphic events, 10 of mRNAs might be related with later metamorphic events, and 16 of miRNAs might be involved in the regulation of metamorphosis. The data provided in this study would be helpful for further identifying metamorphosis-related gene in P. olivaceus

Malignant glomus tumor of prostate: A case report

We reported an 85-year-old patient with malignant glomus tumor (GT) of the prostate. He presented with urinary frequency for more than 2 years and gross hematuria for 7 days. Computed tomography scan showed that the prostate was markedly irregularly enlarged, and the boundary between the prostate and the posterior wall of the bladder was unclear. Bilateral kidneys and ureters were dilated. Biochemical examinations showed that the serum potassium was 7.24 mmol/L and the serum creatinine was 974.6 μmol/L. Transurethral diagnostic resection was performed after restoring homeostasis through several times of bedside blood filtration. The pathological diagnosis was malignant GT. The patient’s renal function recovered after bilateral nephrostomy, and he refused further treatment and was out of contact after 9 months. We summarize the clinical and histopathological features of malignant GT of the prostate in order to improve the early recognition of the disease by clinicians

Growth and mortality rates of bigeye tuna Thunnus obesus (Perciformes: Scombridae) in the central Atlantic Ocean

Age and growth parameters were estimated for bigeye tuna Thunnus obesus Lowe, 1839 sampled from China longline fisheries in the central Atlantic Ocean from October 2002 to July 2003 and from August 2004 to March 2005. The von Bertalanffy growth parameters were estimated at L8=217.9 cm fork length, k=0.23 year-1, and t0=-0.44 year. The total mortality rate (Z) was estimated to be from 0.82 to 1.02, the fishing mortality (F) and the natural mortality were 0.54 year-1 and 0.39 year-1, respectively. The exploitation ratio (E) was 0.35. This study provides the detailed estimates of growth and mortality rate for bigeye tuna in the central Atlantic Ocean, which can be used as biological input parameters in further stock evaluations in this region. However, age analysis, additional validation of the size composition and stock structure are needed for future studies. Rev. Biol. Trop. 57 (1-2): 79-88. Epub 2009 June 30

<title language="eng">Growth and mortality rates of bigeye tuna Thunnus obesus (Perciformes: Scombridae) in the central Atlantic Ocean

<abstract language="eng">Age and growth parameters were estimated for bigeye tuna Thunnus obesus Lowe, 1839 sampled from China longline fisheries in the central Atlantic Ocean from October 2002 to July 2003 and from August 2004 to March 2005. The von Bertalanffy growth parameters were estimated at L8=217.9 cm fork length, k=0.23 year-1, and t0=-0.44 year. The total mortality rate (Z) was estimated to be from 0.82 to 1.02, the fishing mortality (F) and the natural mortality were 0.54 year-1 and 0.39 year-1, respectively. The exploitation ratio (E) was 0.35. This study provides the detailed estimates of growth and mortality rate for bigeye tuna in the central Atlantic Ocean, which can be used as biological input parameters in further stock evaluations in this region. However, age analysis, additional validation of the size composition and stock structure are needed for future studies. Rev. Biol. Trop. 57 (1-2): 79-88. Epub 2009 June 30

Growth and mortality rates of yellowfin tuna, Thunnus albacares (Perciformes: Scombridae), in the eastern and central Pacific Ocean

Age and growth parameters were estimated for the yellowfin tuna Thunnus albacares (Bonnaterre, 1788). Atotal of 443 individuals were sampled from China longline fisheries in the eastern and central Pacific Ocean from February to November 2006. The von Bertalanffy growth parameters were estimated at L&#8734; = 175.9 cm fork length, k = 0.52 year-1, and t0 = 0.19 year. The total mortality rate (Z) was estimated to be from 1.19 to 1.93 year-1, the fishing mortality (F) and the natural mortality (M) were calculated to be 0.91 year-1 and 0.65 year-1, respectively. The rate of exploitation (U) was estimated to be 0.46. This study provides estimates of growth and mortality rate for yellowfin tuna in the eastern and central Pacific Ocean, which may be used as biological input parameters in future stock assessments for the oceanic region. However, age analysis with other techniques, additional validation of the size composition and stock structure are also needed