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ABSTRACT. The common dolphinfish (Coryphaena hippurus) is an important resource for the sport-fishing industry in Mexico. It is captured incidentally by the eastern Pacific purse-seine tuna fishery and in coastal areas by artisanal fisheries. Although it is considered a highly migratory species, only few studies of its movements are available. In this study, the behavior of the common dolphinfish was analyzed by means of acoustic telemetry at three locations within La Paz Bay (southern Gulf of California) from summer to autumn 2013. Acoustic transmitters were attached to six individuals and they were tracked for periods of up to 48 h. Every hour, vertical profiles of temperature and bathymetry were made. To determine the effect of biotic (sex) and abiotic (water temperature and depth, thermocline depth, hour, and bathymetry) variables on the horizontal and vertical movements of tagged organisms, generalized additive mixed models were applied. The results showed a tendency of horizontal movements to the southwestern zone of the bay; two individuals crossed from the eastern to the western side. The average speed was 0.51 m s -1 . The vertical movements showed that the individuals spent 80% of the time above 34 m depth, of which around 45% was spent in the upper 10 m of the water column. During daylight hours they swam in shallow waters (upper 10 m) and at night they performed deeper dives (73 m maximum depth). Biotic and abiotic variables influenced both types of movements; however, bathymetry and temperature largely explained fish movements.Key words: horizontal and vertical movements, Coryphaena hippurus, La Paz Bay, acoustic transmitters. RESUMEN.El dorado (Coryphaena hippurus) es un recurso importante para la pesca deportiva en México. Es capturado incidentalmente por la flota atunera de cerco en el Pacífico oriental y en áreas costeras por la pesca artesanal. Aunque es considerada una especie altamente migratoria, existen pocos estudios sobre sus movimientos. En este estudio se analizaron los movimientos del dorado por medio de telemetría acústica en tres localidades dentro de la bahía de La Paz, parte sur del golfo de California, entre verano y otoño de 2013. Se adhirieron transmisores acústicos a seis individuos y se siguieron durante periodos de hasta 48 h. Cada hora, se hicieron perfiles verticales de temperatura y batimetría. Para determinar el efecto de variables bióticas (sexo) y abióticas (temperatura y profundidad del agua, profundidad de la termoclina, hora y batimetría) sobre los movimientos horizontales y verticales de los organismos marcados, se aplicaron modelos aditivos generalizados mixtos. Los resultados mostraron una tendencia a movimientos horizontales a la zona suroeste de bahía de La Paz; dos movimientos atravesaron la bahía de sureste a suroeste. La velocidad promedio fue de 0.51 m s -1 . Los movimientos verticales indicaron que los individuos estuvieron por encima de los 34 m de profundidad el 80% del tiempo, del cual aproximadamente 45% estuvieron en los 10 m superiores. En horas de lu...

We analysed a historical (1959–2017) database of blue marlin catches reported by the industrial pelagic longline fleet operating in the eastern Pacific Ocean. The time series of catch-per-unit-effort (CPUE) for the time period 1959–2015 was modelled as a function of temporal and environmental variables by using generalised additive mixed models (GAMM). CPUE predictions were made on an independent dataset (2016–2017). Results suggested that a higher nominal CPUE occurred near the equator during boreal winter, spring and autumn, with a shift towards the north during the boreal summer. Two high CPUE events were observed, one in the early 1960s and one in the early 1990s. The final GAMM explained 61% of the total variance of the CPUE time series. Only a small percentage of total deviance was explained by the environmental variables, so we suggest that changes in fleet-targeting practices are the main cause of the large variability in the time series. The final GAMM can be used to predict blue marlin CPUE with a prediction accuracy of 3–8 fish per 1000 hooks. We observed an important decline in CPUE from the early 2000s; the factors responsible for this decline should be further investigated.