Dr. Urzúa-Osorio, Ángel

The traceability of fish species and their resulting food products is essential to maintain the global supply of these goods, allowing us to distinguish and reconstruct the origin and history of their production chain. One way to trace food is through biochemical determinations, which aid in identifying their geographical origin quickly. This study analyzed the fatty acid (FA) profiles of highly migratory fishery resource species (HMRS) from the Southeastern Pacific Ocean (SEPO), and their use as potential tools to determine the geographic origin and nutritional condition of these marine resources. The fatty acids (FAs) presented in fillet or muscle tissue of 18 HMRS were measured as FA methyl esters by gas chromatography. Our results reveal that the swordfish Xiphias gladius presented the greatest variety of FAs, strongly characterized by the presence of saturated, monounsaturated, and polyunsaturated FAs. A similar trend of high diversity in all classes of FAs was observed in tuna species (i.e., Thunnus alalunga; T. albacares; T. obesus), oilfish (Ruvettus pretiosus) and escolar fish (Lepidocybium flavobrunneum). In turn, Lampris guttatus, Makaira indica, and Tetrapturus audax presented an intermediate variety of FAs and the highest amount of saturated and monounsaturated FAs of the evaluated species. Finally, Luvarus imperialis, Coryphaena hippurus and the sharks (Lamna nasus; Alopias vulpinus; Prionace glauca; Isurus oxyrinchus; Sphyrna zygaena) presented a low diversity of FAs, with only saturated FAs strongly predominating. Regarding the total concentration of FAs, the highest average values were recorded in X. gladius, L. flavobrunneum and R. pretiosus. The present study revealed notable differences in the FA compositions of the muscle of diverse HMRS from the SEPO off the coast of Chile, with the swordfish showing the healthiest FAs (i.e., mono and polyunsaturated) for human consumption. The data on FAs collected for HMRS could be used as a reference to characterize the FA profiles of other fisheries in the SEPO (e.g., coastal pelagic fishes). In an ecosystem approach, our findings help us to understand how essential nutrients (i.e., FA biomolecules) are transferred through the marine food web in the SEPO, revealing the diet type and/or feeding habits of HMRS considered as top predators. Furthermore, identifying the FA profiles of fishery resources at a spatial level provides crucial information for their management and conservation, particularly in those resources that are overexploited and also have a critical nutritional importance for human consumption.

In the wide distribution range of the red squat lobster Pleuroncodes monodon in the Southeast Pacific Ocean, there is an important nursery area on the southern coast of Chile. The new juvenile individuals from this nursery area are directly recruited into the adult squat lobster population, which is exploited by industrial fisheries. Despite the importance of new P. monodon juveniles for recruitment estimations in fishery management models, their bioenergetic condition and/or nutritional status at the onset of their benthic phase remain unknown, as are the differences in the biochemical composition and energy reserves of the two sexes, which could help explain the cost of the first breeding event in females. Therefore, in new juvenile squat lobsters with the same degree of immaturity, we quantified and compared between the sexes (female vs. male): the size (cephalothorax length, CL), body biomass (dry weight and organic matter), biochemical composition (proteins, glucose, and lipids), and fatty acid profiles (FAs). The results indicate that the CL of new juveniles was similar between the sexes, while the dry weight and organic matter presented significant differences, with higher values in new juvenile females (NJF) than new juvenile males (NJM). Similarly, the NJF had a higher content of proteins, glucose, and lipids than NJM. The FAs also showed significant differences between the sexes; the NJF had a higher content than NJM in all fatty acid classes (i.e., saturated, monounsaturated, and polyunsaturated), with the FAs DHA (C22:6n‐3), EPA (C20:5n‐3), oleic (C18:1n‐9), palmitic (C16:0), and eicosatrienoic (C20:3n‐3) significantly contributing to the differentiation of FA profiles between the sexes. All of the aforementioned differences among the multiple variables of the bioenergetic condition can indicate biochemical adaptations in the storage capacity of energy reserves, particularly among NJF that must support the high energy cost of the first reproductive event (characterized by embryo production and incubation), which occurs during the austral winter, a period predominated by cold‐water temperatures and scarce food availability in the habitat. Overall, our findings have significant implications in fishery management models. In this case, defining the bioenergetic condition of the new juvenile squat lobsters can aid in predicting the density and stability of the adult population, which is exploited by commercial fisheries.