Resumen del producto

The dolphinfish (Coryphaena hippurus) is a globally distributed marine predator that supports one of the most important coastal fisheries along the Eastern Tropical Pacific (ETP). However, the knowledge about its spatial movements in this area is scarce. The using of the variation of stable isotope values at the baseline, kwon as isoscapes, to track movements of marine predators trough their stable isotope signatures is a growing field in stable isotope ecology. Stable isotope values (d13C and d15N) of dolphinfish muscle (n=220) captured at different locations across the ETP (e.g., Mexico, Costa Rica, Ecuador, Peru, and Oceanic areas) were used to identify transitional and residency zones in this area. Copepod d13C and d15N values were used as baseline values to estimate trophic position, movements, and population dispersal of the dolphinfish. Movement or residence patterns were assumed using the variation in the difference between copepod baseline and dolphinfish d15N values (?15Ndolphinfish-copepod, ‰). Residency was considered when ?15Ndolphinfish-copepod showed values in a range between 3 and 12‰ assuming a threshold where uncertainty of differences in trophic discrimination factors (TDF) across taxa, physiological adaptations, and physical condition is taken into consideration. We further used baseline corrected isotope values (d13CDol-copepod and d15NDol-copepod) of the dolphinfish muscle to estimate isotopic niche metrics to use individual variability of the organisms from different locations and sizes as proxy to infer population dispersal across isoscapes. Values of d13C and d15N showed differences between juvenile and adult dolphinfish and across the ETP. Trophic position estimates ranged 3.1 to 6.0 with a mean of 4.6. Adults and juveniles showed similar trophic position estimates while isotopic niche areas (SEA ‰2) of adults were greater relative to juveniles in every location. Dolphinfish showed a “moderate movement” in all locations based on ?15Ndolphinfish- copepod values, except for Mexico where adults were classified with “high degree of movement by some individuals” and had the greatest niche area (SEA=2.8 ‰2). Population dispersal based on ?15Ndolphinfish-copepod values showed “moderate” and “high” dispersal for adults and “no dispersal” for most juveniles, except for Mexico. Further research is needed to discern the drivers of the bulk isotopic variation for the dolphinfish across the ETP; however, this study provides insight into potential spatial mobility of the dolphinfish across an area of interest for multiple nations, which actively fish on this resource, creating knowledge that will help to improve stock assessments and management of the species.

Palabras clave: Dolphinfish; isotopes stables; Movements; Eastern Pacific

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