Muscle stable isotope and fatty acid data of bigeye and yellowfin tuna harvested in the eastern Pacific Ocean in 2019

Column labels include basic sample information (e.g., ID, date, latitude/longitude, species, body length, sex) as well as a total of 28 fatty acid variables and carbon‑nitrogen stable isotope ratios. All fatty acid concentrations are expressed as relative percentages (%), isotope ratios in per mille (‰), and body length in centimetres (cm).The data cover the period from October 2019 to January 2020, with specific sampling dates fully listed in the “Date” column.

The temporal resolution is at the daily level, with each individual representing an independent record; multiple individuals were sampled on certain days. The sampling area was generally between 0°–10°N and 120°–140°W, with precise latitude and longitude coordinates for each individual provided in the corresponding “Coordinates” column.In terms of data integrity, there are notable missing values and zero entries, as some fatty acids were not detected in certain samples and are denoted as “0” or left blank.

Overall, the data quality is considered to be at a routine level for ecological chemical analyses and is suitable for both individual comparisons and group‑level differentiation assessments.