The effect of temperature on the common octopus life cycle has been well studied. However, how other climatic patterns affect them is poorly understood. The present work emphasises the importance of the temperature on common octopus catches by the small-scale trap fishery off the Canary Islands, and also highlights the effect of the North Atlantic Oscillation (NAO) pattern. As well as an inverse and significant correlation between octopus abundance (measured as CPUE) and Sea Surface Temperature (SST), a direct relationship between abundance and NAO, off the Canary Archipelago, is reported. Using a linear model (lm) with a stepwise procedure, SST is found to be the most important and significant variable in autumn, accounting for 34.21%. Meanwhile, the NAO became more important in spring with 28.64% and a 31.13% of the explained variance in autumn.
Two exploratory trap fishing surveys were carried out from February to April and from June to July 2003, respectively, at depths ranging between 300 and 1200 m, with the objective to assess deep fishery resources of the Canary Archipelago. Despite the fact that the deep-water red crab, Chaceon affinis is a virtually unknown species for the artisanal fishermen of the islands, it was relatively frequent in catches, as an indication of its abundance in deep waters off the archipelago. This crab was captured in the whole range of depths sampled, although its highest abundance was found between 600 and 800 m, on muddy-rocky bottoms. Moreover, significant differences were observed in the average weight and length, according to depth of capture, island of origin, and date of survey. In general, the b parameter of length-weight relationship indicates a negative allometric growth pattern, although in some cases it was not statistically different from isometry, particularly in males. Males were heavier, larger, and more abundant in catches than females. RESUMENSe realizaron dos campañas de pesca exploratoria de febrero a abril y de junio a julio de 2003, respectivamente, entre los 300 y 1200 m de profundidad con el objeto de evaluar los recursos pesqueros profundos del Archipiélago Canario. A pesar de que el cangrejo rey (Chaceon affinis) es una especie prácticamente desconocida para los pescadores artesanales de las Islas, fue relativamente frecuente en las capturas, prueba de su abundancia en las aguas profundas del Archipiélago. Este cangrejo fue capturado en todo el rango de profundidades muestreado, aunque su mayor abundancia se encontró entre los 600 y 800 m de profundidad, tanto sobre fondos fangosos como rocosos. Además, se observaron diferencias significativas en los pesos y tallas medias, según la profundidad de captura, isla y fecha de la campaña. En general, el exponente b de la relación talla-peso indicó un patrón de crecimiento alométrico negativo, aunque en algunos casos éste no fue estadísticamente diferente de la isometría, particularmente en machos. En las capturas, los machos fueron más pesados, grandes y abundantes que las hembras.
SUMMARY:The information provided by the International Commission for the Conservation of Atlantic Tunas (ICCAT) on captures of skipjack tuna (Katsuwonus pelamis) in the central-east Atlantic has a number of limitations, such as gaps in the statistics for certain fleets and the level of spatiotemporal detail at which catches are reported. As a result, the quality of these data and their effectiveness for providing management advice is limited. In order to reconstruct missing spatiotemporal data of catches, the present study uses Data INterpolating Empirical Orthogonal Functions (DINEOF), a technique for missing data reconstruction, applied here for the first time to fisheries data. DINEOF is based on an Empirical Orthogonal Functions decomposition performed with a Lanczos method. DINEOF was tested with different amounts of missing data, intentionally removing values from 3.4% to 95.2% of data loss, and then compared with the same data set with no missing data. These validation analyses show that DINEOF is a reliable methodological approach of data reconstruction for the purposes of fishery management advice, even when the amount of missing data is very high.Keywords: catches, missing data, spatiotemporal data reconstruction, singular value decomposition, DINEOF. RESUMEN: Reconstrucción de datos espacio-temporales de captura a través de funciones ortogonales: el caso del atún bonito-listado (Katsuwonus pelamis) en el Atlántico Centro Oriental. -Los datos de capturas de atún bonito-listado (Katsuwonus pelamis) en el Atlántico Centro Oriental, suministrados por la Comisión Internacional para la Conservación del Atún Atlántico (ICCAT), presentan limitaciones, tales como lagunas de información en las series estadísticas de determinadas flotas o en el nivel de detalle espacio-temporal con el que son suministrados dichos datos. Como resultado de ello, la calidad de tales datos y su utilidad para el asesoramiento en la gestión pesquera es limitada. En el presente estudio se usa la técnica de interpolación por Funciones Ortogonales Empíricas (DINEOF) para la reconstrucción de datos espacio-temporales perdidos, por primera vez aplicada a series de captura. El DINEOF se basa en una descomposición en Funciones Ortogonales Empíricas (EOF) realizada con un método Lanczos. El DINEOF fue aplicado a series con diferentes cantidades de datos perdidos (entre el 3,4% y 95,2% de los valores perdidos), y las reconstrucciones fueron posteriormente comparadas con las series completas originales. Los análisis de validación muestran que el DINEOF es una método fiable para la reconstrucción de series de datos de origen pesqueros, incluso cuando la cantidad de valores perdidos es muy alta.Palabras clave: capturas, datos perdidos, reconstrucción de datos espacio-temporales, descomposición de valores singulares, DINEOF.
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