Dolphinfish Movements in the Eastern Pacific Ocean of Mexico Using Conventional and Electronic Tags

Abstract

Background Dolphinfish, Coryphaena hippurus , are fast-swimming, predatory fish that exhibit fast growth and early maturation. It is an important and potentially renewable recreational and commercial resource throughout their global subtropical to tropical range. While understanding habitat utilization and migratory behavior in these wide-ranging fish is critical to proper regional and international fisheries management, studies have historically relied heavily upon fisheries reported data. This study uses tagging data to explore the vertical and horizontal movements of dolphinfish, focusing on two regions in the Eastern Pacific Ocean (EPO) - west coast of Baja California Peninsula (WBC) and Oaxaca (OAX) coasts of Mexico. Results Adult dolphinfish (fork length 66 cm - 129 cm) were tagged with conventional (n = 132 tags) and electronic tags (n = 30 tags, miniPAT) between 2010 and 2014. Total recapture rate was 3.7%, and greater for males (5.1%) than females (2.4%). Twenty of 30 deployed electronic tags reported, but all did so before the programmed release date, with days at liberty ranging from 3 to 74 (mean = 42 d). Fish remained within their tagging region with the exception of one fish tagged in WBC which exhibited a large southerly displacement, and one fish tagged in OAX which was recovered to the north. Latitudinal (N-S) and longitudinal (E-W) extents of fish movements increased with days at liberty. In general, fish remained near the surface with short excursions below the isothermal layer but larger OAX fish inhabiting warm waters (sea surface temperatures (SST) > ~26 °C) spent more time below the isothermal layer than smaller fish inhabiting colder waters in WBC (SST > ~22 °C). Conclusions This study examines the dynamics of the vertical and horizontal movements of dolphinfish. These movements evoke questions about the size-structure of the dolphinfish’s realized thermal niche, its population stock structure, and its spatiotemporal connectivity patterns in the multinational EPO. Longer tag deployments could show larger displacements and observed differences in orientation of seasonal displacement patterns suggest such long-distance movements would provide opportunities for reproductive mixing through trans-national migrations.

Estimation of first maturity size of dolphinfish Coryphaena hippurus Linnaeus in the Molucca Sea, North Sulawesi, Indonesia

“…Mature individuals seem to gather in the same area for spawning and feeding around the rafts so that more females were caught than males. This result also agrees with Perle et al (2020) and Oxenford (1999) that sex segregation occurs in C. hippurus or males are more susceptible to fisheries than females, even though our finding found more females than males. A higher proportion of females from FADs captures could result from greater availability of females, higher natural mortality in males, or differential growth of both sexes (Benseddik et al, 2019).…”