La captura de macarela (Scomber japonicus) en aguas ecuatorianas en relación a las fluctuaciones de la estructura térmica subsuperficial
Fecha
2019
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Facultad de Ciencias Naturales. Universidad de Guayaquil
Resumen
Se examinaron las posibles relaciones entre las capturas de macarela (Scomber japonicus) en aguas ecuatorianas, en base a datos de captura-por-unidad-de-esfuerzo (CPUE), y las fluctuaciones de la termoclina, derivadas en base a i) la profundidad de la isoterma de 20°C y ii) variaciones del nivel del mar, durante el período 2004-2014. Se utilizó como unidad de esfuerzo los ‘días de pesca’, por lo que en este trabajo la CPUE representa la captura promedio de macarela en toneladas métricas obtenida por cada barco cada día de pesca, siendo usada como un índice relativo de abundancia del recurso. Se aplicaron técnicas estadísticas de correlación y transformaciones no lineales para visualizar el grado de relación entre las capturas de macarela y las fluctuaciones de la termoclina, no habiéndose obtenido ninguna correlación estadísticamente significativa. El análisis de los datos de captura durante el período de estudio, no evidenció una clara estacionalidad en las capturas de macarela en aguas ecuatorianas, siendo los meses de enero a julio los que registraron valores más altos de CPUE. Una relación inversa fue observada entre las capturas de macarela y las fluctuaciones de la termoclina durante los eventos fríos La Niña 2010-2011 y 2011-2012, donde valores más altos de CPUE estaban asociados con termoclinas más someras. En contraste, no fue posible observar alguna relación entre las fluctuaciones de la termoclina y la CPUE de la macarela durante el evento cálido El Niño de moderada intensidad ocurrido en 2009-2010.
The possible relationships between catches of chub mackerel (Scomber japonicus) in Ecuadorian waters, based on catch-per-unit-effort data (CPUE), and thermocline fluctuations, derived from i) the 20°C isotherm and ii) sea level variations, during the period 2004-2014, were examined. ‘Fishing days’ were used as a measure of effort. Thus, in this work, the CPUE represents the mean catch of mackerel in metric tonnes obtained by each vessel in each fishing day, being used as a relative abundance index. Statistical techniques such as linear correlations and non-linear transformations were applied to visualize the degree of relationship between mackerel catches and thermocline fluctuations, finding no correlation statistically significant between these variables. Catch data during the study period showed no evidence of seasonality in mackerel catches in Ecuadorian waters, although highest CPUE values were obtained during the period from January to July. A negative relationship was observed between mackerel catches and thermocline fluctuations during the cold La Niña 2010-2011 and 2011-2012 events, when higher CPUE values were associated with shallow thermoclines. By contrast, no relationship was observed between mackerel CPUE and thermocline fluctuations during the warm, moderate intensity, El Niño event occurred in 2009-2010.
The possible relationships between catches of chub mackerel (Scomber japonicus) in Ecuadorian waters, based on catch-per-unit-effort data (CPUE), and thermocline fluctuations, derived from i) the 20°C isotherm and ii) sea level variations, during the period 2004-2014, were examined. ‘Fishing days’ were used as a measure of effort. Thus, in this work, the CPUE represents the mean catch of mackerel in metric tonnes obtained by each vessel in each fishing day, being used as a relative abundance index. Statistical techniques such as linear correlations and non-linear transformations were applied to visualize the degree of relationship between mackerel catches and thermocline fluctuations, finding no correlation statistically significant between these variables. Catch data during the study period showed no evidence of seasonality in mackerel catches in Ecuadorian waters, although highest CPUE values were obtained during the period from January to July. A negative relationship was observed between mackerel catches and thermocline fluctuations during the cold La Niña 2010-2011 and 2011-2012 events, when higher CPUE values were associated with shallow thermoclines. By contrast, no relationship was observed between mackerel CPUE and thermocline fluctuations during the warm, moderate intensity, El Niño event occurred in 2009-2010.
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MACARELA, SCOMBER JAPONICUS, TERMOCLINA