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Over the past decade, the fishery of Pacific hake, Merluccius productus (Ayres, 1855), has increased in the Gulf of California, Mexico; therefore, any biological-fisheries information is highly relevant for the management of this fishery, and information on age and individual growth would be fundamental to evaluate populations. The objective of the presently study was to assess age, based on otolith structure, and estimate growth parameters through a multimodel approach. Specimens were collected during research cruises of BIP XI from 2014 to 2019. Pacific hake from the Gulf of California ranged in length from 12.5 to 105 cm TL, reaching a maximum age of 13 years, and females were four years older than males. The logistic model was the best model to describe age-size data for both sexes. Females reached 50% of the maximum length at five years old and males reached that length at four years old. [ABSTRACT FROM AUTHOR]

Climate and oceanic conditions determine the Pacific hake (Merluccius productus) distribution pattern. The present work aimed to identify the spatiotemporal relationship between the distribution and abundance of Pacific hake and the environment in the Gulf of California. Information obtained from 6 research cruises carried out between 2014 and 2019 was analyzed. The results showed that the Gulf of California hake reaches a total length of 105 cm, exhibiting sexual dimorphism at total lengths >73 cm. The highest resource biomass (68,260.37 t) was found in February 2019 at depths between 200 and 300 m and the lowest was found in October 2016 (6,917.80 t) at depths between 100 and 150 m. These centers of abundance were located at bottom temperatures between 13 and 14 °C, north of Ángel de la Guarda Island and between the great islands (Tiburón Island and Ángel de la Guarda Island). After adjusting generalized additive models between seasonal hake catches and different environmental, spatial, and temporal variables, bottom temperature was found to be the variable that best described these centers of abundance. [ABSTRACT FROM AUTHOR]

The stomach contents of 1261 striped marlins caught from 2007 to 2010 by the sport-fishing fleet of Cabo San Lucas, Baja California Sur, Mexico, were analysed, taking into account sea surface temperatures estimated using satellite images of the study area and the Oceanic Niño Index (ONI). The analysis allowed the identification of three anomalously cold periods during 2007, 2008 and 2010 and a warm period in 2009. The stomach content results showed 89 different prey items eaten during the study period. Of the specimens captured, 868 (69%) stomachs contained food items. The most important prey items were cephalopods (Dosidicus gigas and Argonauta spp.) and fish (Scomber japonicus , Selar crumenophthalmus and Sardinops caeruleus). Despite having a broad trophic spectrum, the striped marlin was classified as a specialist consumer, with Bi = 0.03. Based on the diet breadth value and the prey-specific index of relative importance (PSIRI), the jumbo squid, D. gigas , was the main prey species, coinciding with cold periods. On the other hand, the fishes S. caeruleus and S. japonicus showed the highest PSIRI values during the 2009 warm anomalies. Analysis of similarity showed the formation of four groups in relation to PSIRI values. According to a non-metric multidimensional scaling ordination, these groups were formed with a similarity of 30% and a stress of 0.17. These results demonstrate inter-annual variation in the diet as well as in the availability and abundance of prey items. [ABSTRACT FROM AUTHOR]

The trophic spectrum of both Eucinostomus entomelas and Micropogonias megalops, the two most abundant fish species in Laguna Las Guásimas, Sonora, México is described in our study. A total of 21 types of prey were identified belonging to seven taxonomic groups (Crustacea, Mollusca, Annelida, Rhodophyta, Copepoda, Echinodermata and Chordata) to analyse the feeding spectra and diet breadth. The preferred prey items of Eucinostomus entomelas (Dark-spot mojarra) were Polichaeta (index of relative importance = 46.7%), followed by bivalves (36.6%), and Luidia columbia (5.6%), while those of Micropogonias megalops (Bigeye croaker) were Portunidae (22.8%) followed by Gammaridae (20.55%) and Crustacea (18.37%). The trophic spectrum for male E. entomela was composed of Bivalvia and Polychaeta. Both predators showed low values in diet breadth (E. entomelas (Levin's index Bi = 0.14) and M. megalops (Levins's index Bi = 0.43)). The low trophic overlap (Cλ = 0.14) between predators suggests that both fish are not competing with each other for food resources in Laguna Las Guásimas. [ABSTRACT FROM PUBLISHER]