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.
Highlights
The movement of organisms is defined as a change in their spatial location as a result of a complex interaction between internal factors that promote movement and interpret why, how, when, and where to move and external factors that affect movement (Nathan et al 2008)
It is important to know the movements and habitat preferences of pelagic fish because their vulnerability to fishing is influenced by factors such as the depth they inhabit, travelling speed, residence time in certain areas, and school formation (Brill and Lutcavage 2001)
The horizontal and vertical movements of C. hippurus in LPB were identified in relation to biotic and abiotic factors
Summary
The movement of organisms is defined as a change in their spatial location as a result of a complex interaction between internal factors that promote movement and interpret why, how, when, and where to move and external factors (biotic and abiotic) that affect movement (Nathan et al 2008). It is important to know the movements and habitat preferences of pelagic fish because their vulnerability to fishing is influenced by factors such as the depth they inhabit, travelling speed, residence time in certain areas, and school formation (Brill and Lutcavage 2001). The common dolphinfish, Coryphaena hippurus Linnaeus, 1758, is a pelagic species distributed in tropical and subtropical seas (Palko et al 1982). It is ecologically important because it is a top predator in the pelagic ecosystem (Varghese et al 2013). It is opportunistic (TrippValdez et al 2010), highly voracious, and has a wide trophic spectrum, and its food habits are closely linked to the epipelagic environment (Aguilar-Palomino et al 1998)
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