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Chilean hake (Merluccius gayi gayi) is one of central Chile's most important demersal resources, and its fishery involves an artisanal fleet that mainly uses gillnets. In the recent history of the fishery, there has been a decrease in catch sizes and a progressive reduction in mesh sizes. This study aimed to analyze the factors that influenced the mean catch sizes of Chilean hake between 2001 and 2018 to understand this situation, correlating the response of fishermen with the capture efficiency of the nets used. Applying a generalized linear model, a significant effect of the factors year, port (zone), and mesh size were observed on the mean size of individuals caught. The model explained 85% of the deviation, the greatest relative contributions being made by the factors year (53.6%) and port (30.2%). A lower effect was estimated for the mesh size factor with 1.2% deviance. These findings suggest that the progressive reduction in mesh sizes is associated with a response to the demographic change in the stock. Differentiated management measures by zones could be considered in the fishery, given the estimated differences. [ABSTRACT FROM AUTHOR]

The abundance of juvenile fish changes due to endogenous processes, and determining the functional relationships among conspecifics is essential for fisheries' management. The hake (Merluccius gayi) is an overexploited demersal fish widely distributed in Chile, from 23°39′ S to 47°00′ S in shallow and deep water over the continental shelf and shelf break. We studied the spatiotemporal distribution of hake juveniles (from ages 0 and 1), emphasizing endogenous relationships among juveniles and adults. The abundance per age data were obtained from bottom trawl cruises carried out in the austral winter between 1997 and 2018. Generalized additive models showed a similar spatiotemporal pattern for ages between 0 and 1, and negative effects of adult hake aged seven and older on the abundance of the young generation. Regarding the changes in juvenile abundance, the residual deviance of selected models explained 75.9% (for the age 0) and 95.3% (for the age 1) of the null deviance, revealing a significant increase in juvenile abundance from 2002 to 2007 and subsequent abundance stability at higher levels. Furthermore, the expansion in the abundance of juveniles after 2002 was favored by the low abundance of older adult hake, most which are able to cannibalize young hake. Our results highlight the importance of endogenous factors in the spatial distribution of Chilean hake juveniles to identify nurseries or juvenile areas free of potential cannibal adults. [ABSTRACT FROM AUTHOR]

Society's awareness of environmental issues increases every day. In this context, the concept of carbon footprint (CF) arises as a calculation tool that quantifies greenhouse gasses (GHG) emitted during the life cycle (LC) of a product. This calculation method is used in many productive sectors throughout the world; however, the Chilean fisheries sector has not notified the use of this tool or initiatives in that sense. This study performs a calculation of the CF of artisanal gillnet hake (Merluccius gayi gayi) fishery of the Caleta Portales, located in Valparaíso, Chile. The ISO 14040: 2006 methodology was used. The analysis was limited from the boat departure until the catch is landed, as a gate-to-gate life cycle assessment (LCA). The fuel consumption data and information related to the fleet were used as the main source of information. The Caleta Portales hake landings were 1,340.484 kg in 2011 and 703,411 kg in 2012. This fleet released into the atmosphere in 2011, 0.47 CO2 equivalent per kg of hake landed, and 0.58 kg CO2 eq, in 2012. It is the first result of CF reported in a Chilean fishery. This result can lead to an increase in the competitiveness of this hake fishery, as it can generate a positive impact on encouraging consumers to prefer the consumption from those places that have calculated the CF and are less than other food products. [ABSTRACT FROM AUTHOR]

• Underwater observations of jumbo squid in a trawl for Chilean hake were made using video cameras. • Quantitative analysis of the selection process using a rigid grid to reduce bycatch was made. • Jumbo squid was positively selected by the rigid grid. • Some obstacles was observed during the selection process, with losing efficiency in the escape. • Redesign components to improve efficiency of the selection system are discussed. Observations via underwater filming were obtained to improve understanding of the behavior and selection process of jumbo squid (Dosidicus gigas) in response to a rigid grid in the Chilean hake (Merluccius gayi gayi) trawl fishery in central Chile. The individual fates of jumbo squid were examined to study the efficiency of the selection system. The number of escaped versus captured specimens was quantified. During the selection process, we observed obstacles that impeded the escape process, leading to retention of jumbo squid and limiting the selectivity effectiveness. The analysis showed that 69.8% of jumbo squid escaped the net and 75.5% faced obstacles that generated retention in the sorting process. Longer retention times led to a saturation of the selection system. The target species was successfully selected by the sorting system, in which 87.1% of Chilean hake entered the codend through the grid. We discuss the need to redesign components of the selection system to improve efficiency. [ABSTRACT FROM AUTHOR]

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Southern hake (Merluccius australis) supports one of the most commercially important fisheries in southern Chile. Its main recognized spawning area is located offshore in canyons along the continental shelf margins of northern Patagonia, but recently eggs have been observed in inshore channels and fjords. Whether the eggs reported in inshore areas were spawned in this area by winter-spring resident females or by females entering into the inner areas from an offshore spawning zone is not yet clear. As a first step toward answering this question, here we examine the fatty acid (FA) composition of female southern hake gonad, liver, and muscle tissues to explore whether they could be used as bio-indicators of the origin of females collected in the inshore (Gulf of Ancud) and main spawning offshore areas (around the Guafo and Guamblin Islands) during winter. Total lipid fraction was extracted with ASE from the tissues, followed by saponification and derivatization, which were analyzed via gas chromatography-mass spectrometry (GC-MS). Fatty acid identification was carried out based on the comparison of the mass spectra and retention times. Fatty acid concentrations were calculated using a methyl ester FA curve. Results showed that, while in offshore females liver tissues presented the highest fatty acid contents, in inshore females the highest fatty acid concentrations were found in the gonads. Among polyunsaturated fatty acids (PUFA), docosahexaenoic acid (DHA) contents in the gonads were higher inshore than offshore. Conversely, in liver and muscle tissues, EPA contents were higher offshore than inshore. In liver and muscle tissues, docosahexaenoic acid (DHA) was higher inshore than offshore. The DHA/EPA ratio decreased in gonads from inshore to offshore zones. Overall, our results reveal that the FA in the three tissues differed between females collected from inshore and offshore zones, suggesting that their main food source and overall trophic webs were different, and therefore that these groups of fish may reside separately in each zone during the winter season. Fatty acids can therefore be utilized as bioindicators of the origin of females present in inshore areas during the spawning season, supporting the hypothesis of alternative reproductive zones for southern hake in the northern Chilean Patagonian area. [ABSTRACT FROM AUTHOR]

The articled discusses research investigating species composition in the artisanal, or small-scale, gillnet Chilean hake (Merluccinus gayi gayi) fishery in central Chile. Topics include the importance of species composition in the management of commercial fisheries, the method used to identify and quantify the species caught in the artisanal glllnet Chilean hake fishery between the Valparaiso and Biobio regions, and the rate of occurrence of several by-catch species.

Somatic growth was studied in the Chilean hake stock off central coast of Chile, through the application of Von Bertalanffy equation (vB) as a non-linear mixed effect model (NLME) on length-at-agedata derived from otolith readings made at Instituto de Fomento Pesquero since 1972. Average growth rates for each year from 1972 to 2009 were estimated. Growth parameters of vB curves were analyzed for three major periods regarding changes in stock biomass (1972-1990, 1991-2003 and 2004-2009). Results indicated that the average growth rate showed inter-annual variations that did not exceed ±15 cm of total length around the historical average of males and females, showing no persistent tendency towards sustained increase or decrease in somatic growth rate. Growth curves obtained with the vB parameters, estimated for the three periods, showed a similar trajectories until age 7 and 8 years, in both male and females. Changes after this age may be a result of a decrease of larger fish removed by the selective effect of fishing, which triggered variations in the fitted curves, but not necessarily changes in somatic growth of these ages in the population. The results demonstrated that the individual growth of hake has not changed significantly since 1972, without observing a density-dependent effect with decreasing abundance. [ABSTRACT FROM AUTHOR]

Abstract: The Chilean hake (Merluccius gayi gayi) is one of the most important demersal resources fished in Chile since the early 1940s. Since 1993, an acoustic survey program was established to assess the abundance of this resource. A sudden decrease in abundance was observed after 2002, along with changes in the species demography and spatial distribution. These changes represent a spatial re-distribution of the stock (latitude, longitude, and depth) which was associated with concomitant changes in environmental conditions (temperature, salinity, and dissolved oxygen). The main aim of this paper is to determine habitat preferences in Chilean hake and associated changes in its abundance with environmental conditions. Estimates of Chilean hake abundance were based on acoustic survey conducted between 1993 and 2006 from Coquimbo (29°30′S) to Chiloé Island (41°28.6′S). Chilean hake abundance was modelled using generalised additive models with environmental variables and location as covariates. In the interannually analysis, location and temperature were the most important explanatory covariates of Chilean hake abundance. Analyses of the data across years revealed that time, Chilean hake aggregation depth, and temperature were the most important covariates. The changes observed in spatial distribution can be divided into two periods. During the first period (1993–2001) high values of Chilean hake abundance were found in salinities between 34 and 34.4psu, temperatures of 8 and 11°C, and depths between 125 and 400m. During the second period (2002–2006) the stock increased in the southernmost area closer to the coast and were associated with low salinities (<34psu). In this paper we discuss the spatial and temporal changes in Chilean hake abundance, their habitat preferences, and how the association between abundance and environmental variables changes during these periods of high and low abundance. [Copyright &y& Elsevier]

Genetic variation and divergence among samples of Chilean hake Merluccius gayi, from three localities off the coast of Chile and one locality off the coast of northern Peru, were assessed using sequences from the control region of mitochondrial DNA. Homogeneity tests revealed occurrence of at least three distinct genetic stocks of M. gayi within the region sampled. Factors potentially contributing to genetic divergence among M. gayi probably include hydrodynamics and behaviour. [ABSTRACT FROM AUTHOR]

Using the data collected in a size selectivity experiment on Chilean hake (Merluccius gayi gayi) carried out in 2000, the selectivity parameters for four codend mesh sizes (100, 110, 130, and 140 mm of mesh size opening) were estimated and modelled by the SELECT model. These analyses included considerations of the sampling proportions of the catch in the codend and cover. Furthermore, the analyses took into account between-haul variation. The l50 values were 30.8, 29.9, 30.0, and 41.2 cm of total length, respectively, values lower than the estimates obtained from previous studies. The contribution of explanatory variables to the selectivity model was also tested in order to determine the role of mesh size, catch size (in number), and towing speed. Increases in catch size and in towing speed were accompanied by decreases in the l50 estimates. These results demonstrate how incorporation of subsampling effect and explanatory variables to model between-haul variation can improve selectivity estimates and management of a valuable resource. [ABSTRACT FROM AUTHOR]

Abstract: Variability in Chilean hake reproductive tactics off central Chile was assessed by analyzing ichthyoplankton samples from nine oceanographic cruises (1996–2005) and through experimental trials with early life stages (eggs, yolk-sac larvae) during the main (austral spring) and secondary (late summer–early autumn) spawning seasons. Abundant eggs in the plankton (1300–2000 eggs per 10m2) and historical adult reproductive data showed the highest reproductive activity in austral spring, with large egg aggregations near shelf break (50–100m depth). Large, recently spawned eggs (1.15–1.20mm diameter) were advected nearshore by coastward subsurface flows in the spring upwelling season. Experimental trials indicated that recently hatched larvae (3.4–3.5mm) consumed their yolk-sac (0.17–0.41mm3) in 3–4days at 10–12°C; plankton sampling indicated that larval hake remained at mid-depth (50–100m) without showing daily vertical migrations until completing their caudal fin formation (∼15mm). During the secondary reproductive peak, hake spawned nearshore, when smaller eggs (0.95–1.13mm) and recently hatched larvae (2.2–2.6mm notochord length) occurred in surface waters (0–10m depth). Their relatively large yolk-sac volumes (0.57±0.11 mm3) provided endogenous nourishment for at least 5days at 10°C, according to experiments. In the field, preflexion larvae occurred mainly in the mixed layer (0–25m) and started ontogenetic daily vertical migrations at 7mm. A strong decline occurred after 2002 in the adult Chilean hake biomass (estimated by hydroacoustic surveys) and body size, coinciding with variations in spawning locations (more coastward in early spring 2004 and 2005) and decline in egg size. Thus, recent variations in Chilean hake reproductive tactics may reflect an indirect effect of declines in the parental population size. [Copyright &y& Elsevier]

Abstract: This study was conducted to determine the reduction in bycatch and the loss of target catch in trawl hauls for three commercial crustacean species (yellow squat lobster, Cervimunida johni, nylon shrimp, Heterocarpus reedi, and red squat lobster, Pleuroncodes monodon) in central Chile. Two experiments were carried out using the covered codend method; the first used different mesh sizes (56 and 70mm, knot-centre to knot-centre) and shapes (diamond and square), and the second tested different reduction devices (escape panel and sorting grid). We analysed the escape proportions of the species caught and the size frequency distributions of the target species and Chilean hake (Merluccius gayi), the main commercial bycatch species. The results demonstrate that it is feasible to significantly reduce bycatch while keeping losses within acceptable ranges. In particular, the best option for yellow squat lobster was the combination of a 70-mm diamond mesh with an escape panel that reduced non-target and target catches by 48% and 7%, respectively. For nylon shrimp, the best option was the use of a 56-mm diamond mesh with a sorting grid that reduced non-target and target catches by 41% and 11%, respectively. Although the results for red squat lobster were not as promising, they will help to guide future research. [Copyright &y& Elsevier]

The Chilean hake (Merluccius gayi gayi) is the predominant groundfish species inhabiting the southern Humboldt, mainly from Coquimbo (29° S) to Puerto Montt (42° S). At present there is only limited knowledge on the spatial distribution of juveniles of this species, particularly concerning its dependence on key physical characteristics. On the basis of annual surveys carried out during austral winters from 1997 to 2006, changes in the presence of juveniles were studied using Generalized Additive Model techniques. Temporal factors and spatial effects were more important than single physical variables in explaining the presence of juvenile hake (<34 cm total length). Juvenile hake had a preference for shallower waters. Although salinity and oxygen were significant, their contribution was marginal. Juvenile hake seem to prefer shallow oxygenated waters, but the nonlinear relationships and partial secondary peaks detected in salinity and oxygen probably only reflected the influence of three water masses found in the winter habitat. Endogenous factors could be more important in determining temporal and spatial changes in the proportion of juvenile hake. An important change in the presence of juveniles has occurred since 2004, coinciding with a significant decline in biomass of adult hake. It is postulated that cannibalism pressure from adults has probably declined and that spatial and temporal changes in the presence of juvenile hake seem to be more associated with fishery-induced demographic effects. [ABSTRACT FROM PUBLISHER]

The article discusses a study which examined the effect of hook size and seasonality on the artisanal long-line fishery of southern hake, Merluccius australis, in Chile. The study reveals no significant effects in either catch size composition or in catch rates between hooks of different size. However, the existence of a significant seasonal effect was verified on the catch rates. The researchers recommend that fishermen use alternative fishing gear and management measures for the fishery. They also suggest assigning differential catch quotas considering the spatial-temporal distribution of the resource and its migratory processes.

The diving behaviour of female southern rockhopper penguins ( Eudyptes chrysocome) was studied at Noir Island (54°30′S–73°00′W), Chile, in the southeast Pacific Ocean. This isolated island is located at the edge of the continental shelf in an area where the Humboldt Current originates, and holds a population of more than 150,000 breeding pairs. On 13 December 2005, four TDRs were successfully attached to females at the end of the brooding period and recorded diving activity at intervals of 2 s over the next 4 weeks. In total, 40 complete foraging trips were recorded. Trip duration was on average 42.4 ± 40.1 h and the proportion of overnight trips (60%) was the highest value found so far for this species. Mean dive depth and dive duration was 20.6 ± 19.4 m and 63.7 ± 36.4 s, respectively. The diving effort was higher than that of brooding females from the Indian Ocean and comparable with that of conspecifics from colonies in the southwest Atlantic in terms of diving rate (38 ± 14.2 dives h−1), but slightly lower as regards the proportion of time spent underwater (61 ± 10.5%). This study confirms that the diving behaviour of rockhopper penguins varies as a function of the physical and biological characteristics of the foraging areas and of the particular stage of the breeding season. [ABSTRACT FROM AUTHOR]

Size-based prey selectivity in Chilean hake (Merluccius gayi gayi) is analyzed using a data base of stomach contents collected from 1992 to 1997. The Ursin prey selectivity index and the size-based selectivity coefficients were calculated by age for the Chilean hake (cannibalism); the galatheids squat lobster (Pleuroncodes monodon) and yellow squat lobster (Cervimunida johni); the clupeiforms common sardine (Strangomera bentincki) and anchovy (Engraulis ringens); and other combined prey. Hake are confirmed to consume larger prey as they grow and individuals over two years of age show a preference for the young fraction of the hake population (0-4 years; cannibalism), anchovy (0-1 year), and lobster (0-1 year). Hake over four years of age also prefer squat lobster and yellow squat lobster (> 2 years). High selection coefficients are found for the remaining prey, mostly zooplankton (euphausids) and myctophids, with predators from 0 to 4 years. The selection coefficients calculated herein constitute a quantitative basis for improving multispecific evaluation models that allow the quantification of the trophic impact of Chilean hake on commercially important species of the benthic-demersal and pelagic system off central-southern Chile. [ABSTRACT FROM AUTHOR]

Presents a study which hypothesized that a change in spawning site for the Patagonian stock of Argentine hake, or Merluccius hubbsi, can affect species recruitment. Background on Argentine hake; Relationship between egg production and recruitment; Abundance of hake and location of spawning females; Spatial pattern of M. hubbsi spawning aggregation inshore and offshore of the north Patagonian area in Argentina and Chile between 1988 and 2001.

Explores several biological, fishery, and environmental aspects that influence the historical abundance of two hake populations in Chile. Similarity between the timing of the spawning season for both hakes; Role of environmental variability in population dynamics and sustainability of hake species; Importance of mixing versus stratification of water masses in the spawning area.

The article discusses the experimental fishing in the salmon farming regions of southern Chile to determine abundance and distribution of such exotic salmon populations, and their effect on native organisms. It notes the most commonly farmed salmon species including rainbow trout (Oncorhynchus mykiss), coho salmon (Oncorhynchus kisutch), and Atlantic salmon (Salmo salar). Results showed artisanal fishing may control escaped salmon, and they could compete with native southern hake and mackerel.

Abstract: The behaviour of Chilean hake (Merluccius gayi gayi) in a bottom trawl was observed with an underwater camera positioned in the trawl mouth and in the front of the codend extension. Significant differences were observed in the fish behaviour in the two sections, demonstrating that this species is more active in the mouth of the net. The fish activity was lower in the trawl extension, where the fish were merely carried by the flow into the net. [Copyright &y& Elsevier]