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Age, growth and length-at-maturity of the Argentine hake (Merluccius hubbsi) were studied in the northernmost limit of the species distribution in the south-western Atlantic. A total of 351 otoliths and information from 1610 specimens sampled from the industrial double-rig trawl landings between May 2013 and April 2014 were used. Age and growth were estimated by counting and measuring increments in sectioned sagittae otoliths, and length at maturity was estimated based on macroscopic gonadal analysis. For both sexes, hepatosomatic index and condition index increased mainly during spring, reaching a maximum at the end of summer before the subsequent spawning season began. Gonadosomatic index was highest in April, believed to correspond with peak spawning. The annual periodicity of alternate opaque and translucent zones was validated by marginal increment analysis. Growth curves were fitted to back-calculated size at age by fitting the three-parameters von Bertalanffy growth function. The maximum age was 5 years in fish of either sex. Females attained larger sizes than males. The parameters of the von Bertalanffy growth equations were: L∞ = 533 mm, k = 0.231 year−1 and t0 = −0.935 year for females; L∞ = 394 mm, k = 0.405 year−1 and t0 = −0.463 year for males. The mean length and age at first maturity was 273 mm at 1.9 years for males and 274 mm at 2.0 years for females. [ABSTRACT FROM AUTHOR]

Argentine hake (Merluccius hubbsi) was stored chilled for 8 days. The evolution of fluorescence of the aqueous and organic extracts of muscle during storage at 4°C was studied and correlated with common damage indices; pH, total volatile basic nitrogen, free fatty acids, and the fluorescence intensity of the aqueous phase showed a good correlation with storage time. The excitation-emission matrices of the aqueous extracts were also obtained. A fluorescence landscape that could be attributed to tryptophan decreased with storage time, meanwhile a peak (around 340 and 400 nm for excitation and emission wavelengths, respectively) is developed during chilled storage. [ABSTRACT FROM AUTHOR]

The present study evaluated the possible occurrence of cryptic species among Merluccidae from Argentina by examining sequences of cytochrome c oxidase subunit I ( coI) mtDNA. This approach can discriminate Merluccius hubbsi and Merluccius australis; specimens with morphological diagnostic characters of Merluccius patagonicus formed a cohesive cluster with M. hubbsi specimens. BIN analysis confirmed the effectiveness of barcoding within a global context. [ABSTRACT FROM AUTHOR]

Morphology and morphometry of the sagittae otolith were studied in young of the year Argentine hake, Merluccius hubbsi in the Southeastern Atlantic. Geographical variation in the growth pattern of the young of the year Merluccius hubbsi was correlated with the differences found in otolith morphometry, relative growth, ring positions, as well as the formation of a new ring. The otolith development of M. hubbsi throughout its area of distribution accompanies an increasing northward temperature gradient, resulting in bigger otoliths and greater variability of ring position from northern to southern area. The canonical discriminate analysis showed that the otolith length and height explained most of the variation of the first discriminant function. We found significant differences in the discriminant scores between those samples from northern and southern area. As regards the Uruguayan coast and Southern Brazil, age groups zero shared some similarity as well as differences in growth; environmental features explain these differences but their effect on the adult fishes growth is still unknown. [ABSTRACT FROM AUTHOR]

The performance of management measures adopted to reduce the catch of small-size fish in trawl fisheries requires a proper evaluation taking into account that different factors (e.g., the behavior of fishermen, gear efficiency, market forces, and weak controls) may affect the results. The high bycatch of juvenile Argentine hake Merluccius hubbsi recorded in the trawl fishery of San Matías Gulf, Argentina, could be an indication of a suboptimal harvesting pattern that should be addressed. Regulations to mitigate this problem (i.e., a minimum mesh size and the seasonal closure of a nursery area) were imposed in 1997-1998. The purpose of this study was to assess the efficacy of the size-selectivity measure 10 years after its implementation based on two key indicators: the presence of juvenile Argentine hake in catches and discard rates. Our results show that this measure was ineffective in reducing the catch and discard of juveniles and that both indicator values increased during the period analyzed. This failure could be the result of the limited scientific advice available when the measure was designed or poor implementation, monitoring, and control strategies. [ABSTRACT FROM AUTHOR]