Pleuroncodes Monodon Research Articles

Living Along Distribution Margins: Differences in the Body and Biochemistry of Red Squat Lobster Morphotypes (Grimothea monodon) from the Humboldt Current System

Grimothea monodon, an important fishery resource in the Humboldt Current marine ecosystem (HCE), present two contrasting morphotypes (PM, pelagic morphotype; BM, benthic morphotype). The fishery management of G. monodon is focused on understanding only fishery aspects that apply to a limited area, and there are currently no studies that evaluate the nutritional status of these morphotypes. This study evaluated the biological performance of PM and BM, analyzing the body (size, CL; weight, W; condition factor, Kn) and biochemical condition (glucose, G; proteins, P; lipids, L; fatty acids, FAs). The results reveal that G. monodon showed differences in CL and W between morphotypes, with higher values in BM than PM. The Kn was different between morphotypes with a tendency of isometric growth. In turn, the G contents were higher in PM than BM, while the contents of P, L, and FAs showed an opposite tendency, with higher contents recorded in BM than PM. Our findings suggest that the Kn should be included to strengthen the biological parameters and their relationships used in fishery management models. Differences in the biochemical condition between morphotypes can be considered potentially adaptive, in response to the combined effect of environmental factors that vary in the HCE.

Distribution patterns of the demersal fish assemblage off central Chile.

Thespatial and temporal distribution of the fish fauna in the fishing area of Pleuroncodes monodon, off Central Chile, is analysed. Haul-by-haul information from four surveys was taken into account (April 1982 and 1983, and March and November 1984). The demersal fish fauna exhibits two boundaries, one at depths of around 250 ± 50 m and the other one at depths of around 100 m. Consequently, three fish assemblages are recognized: inshore over the continental shelf, offshore over the continental shelf, and over the upper continental slope. Temporal and spatial changes in the fish assemblage are clearly recognized with M. gayi as the dominant species, being replaced in depth mainly by the grenadier fish Coelorinchus aconcagua.

Alimentación del bonito Sarda chiliensis (Pisces: Scombridae) en el norte de Chile

The diet of Sarda chiliensis from artisanal fishing in northern Chile from May 2017 to March 2018 was analyzed. Stomach content analysis resulted that the most frequent and abundant prey was Pleuroncodes monodon with the highest value of Index of Relative Importance in the diet (%IRI= 45.8) followed by Engraulis ringens. No correlation was found between the length of the main prey (P. monodon and E. ringens) and the size of the predator. S. chiliensis tended to be a generalist predator (Bi= 0.75) with a trophic position NT= 4.3, a trophic level characteristic of species considered top predators.

Using a time-dynamic food web model to compare predation and fishing mortality in Pleuroncodes monodon (Galatheidae: Crustaceae) and other benthic and demersal resource species off central Chile

The stock biomass of the carrot prawn (Pleuroncodes monodon) in the south-central area of Chile (33º–39°S) has decreased progressively in the last 12 years. The depletion and lack of recovery of carrot prawn and other fish and crustacean stocks has been attributed mostly to fishing mortality (F). Predation can be also an important factor for the dynamics of marine species, especially those that are important prey in the ecosystem, like the carrot prawn and other demersal crustaceans. However, predation mortality (M2) has been less studied and quantified in Chile and elsewhere. Therefore, it is important to estimate and compare predation (M2) and fishing (F) mortality to understand their individual and combined effects on the dynamics of fishing stocks. In this study, we analyzed the biomass changes of carrot prawn and other components of the marine food web in south-central Chile from 1992 to 2018. For this, we built a food web model that was later fit to time series of observed biomass and catch data, using observed fishing mortality as forcing factor. We used the Ecopath with Ecosim software as modeling platform. This model provided M2 and F series for carrot prawn and other demersal crustaceans, which were compared to evaluate their relative contribution to total mortality (Z) from 1992 to 2018. The quantitative model considered 29 functional groups, from primary producers to top predators, and the following fishing fleets operating in the study area: artisanal and industrial purse seine fleets, artisanal and industrial hake trawling fleet and demersal prawn trawling fleet. The results indicated that M2 was the main component of Z in adults and juveniles carrot prawns, with Chilean hake as the main predator in both cases. M2 was responsible for 84 % and 86 % of Z of adults and juveniles of carrot prawns, respectively. M2 was also greater than F in yellow prawns (Cervimunida johni), whose main predator was big eye flounder (Hippoglossina macrops). In contrast, F was greater than M2 for the nylon shrimp (Heterocarpus reedi). We conclude that the stock dynamics of the carrot and yellow prawns has been strongly influenced in recent decades by the predation by Chilean hake on pre-recruits of carrot prawn as prey and bigeye flounder on yellow prawn as prey. We recommend that M2 should be considered both in evaluating the past dynamics of these stocks used to establish their status and in future projections used to establish biologically acceptable catch.

The Red Squat Lobster Pleuroncodes monodon in the Humboldt Current System: From Their Ecology to Commercial Attributes as Marine Bioresource.

This study focused on gathering available information on Pleuroncodes monodon, a widely distributed crustacean in the Humboldt Current System. Off the Chilean coast, this species presents benthic habits and constitutes the main resource of the industrial crustacean fishery; many studies have been carried out on its life cycle during the last century. In contrast, off the coast of Peru, this species exhibits mainly pelagic habits, with latent information gaps on aspects of its life history and no commercial fishery activities, such as catching, taking or harvesting from the marine environment. P. monodon is an ecologically important species, as a source of energy for its predators, which include invertebrates, birds, marine mammals and fish of commercial interest. Thus, P. monodon seems to play a key role in this ecosystem, mainly as an intermediate link between top predators and the first links in the food chain. In addition, this species presents various adaptation strategies to the changing oceanographic parameters of the areas it inhabits, even tolerating hypoxic environments and great depths in order to avoid being predated. Likewise, from an economic viewpoint, it has a high commercial value as a marine bioresource with great potential in the pharmaceutical and food industries. Considering this, more studies must be carried out to corroborate the biological, ecological, and fishing importance of this species in order to generate efficient management measures and ensure a sustainable fishery.

Extraction of bioactive lipids from Pleuroncodes monodon using organic solvents and supercritical CO2

A huge volume of Engraulis ringens (Peruvian anchoveta) is caught together with the species Pleuroncodes monodon (munida), whose potential bioactive lipids are not commercially exploited. In the present study, lipid with carotenoid pigment (astaxanthin) and essential fatty acids (EPA+DHA) were obtained from munida lipids extracted with hexane:isopropyl alcohol (He-I), acetone (Ac), ethanol (Et) and supercritical CO2 + ethanol (SC-CO2-Et). The functional quality of the fatty acids was determined by atherogenicity index (AI), thrombogenicity index (TI) and the hypocholesterolemia:hypercholesterolemia (H:H) ratio. The highest astaxanthin (ASTX) contents (4238.65 and 4086.71 µg/g lipid) corresponded to extractions using Ac and SC-CO2-Et. EPA+DHA ranged from 31.15 to 31.85% and the functional quality ranges were between 0.56-0.61 (AI), 0.19-0.21 (TI) and 1.73-1.81 (H:H). Consequently, SC-CO2-Et extraction would be advisable because of its low environmental impact. The IA and IT quality indexes suggest that the consumption of munida lipids would be healthy, although the H:H ratio shows the opposite.

Spatio-temporal patterns of the crustacean demersal fishery discard from the south Humboldt Current System, based on scientific observer program (2014-2019).

This study summarises six years of spatio-temporal patterns of the discarded demersal community fauna recorded by onboard scientific observer program for both artisanal and industrial crustacean fisheries between 2014 and 2019, from mesophotic to aphotic depths (96 to 650 m) along the southern Humboldt Current System (28-38°S). In this period, one cold and two warm climatic events were observed during the austral summer 2014, 2015-2016 (ENSO Godzilla), and 2016-2017 (coastal ENSO), respectively. Satellite information showed that Chlorophyll-a concentration varied seasonally and latitudinally, associated with upwelling centres, while equatorial wind stress decreased southward of 36°S. Discards were composed of 108 species, dominated by finfish and molluscs. The Chilean hake Merluccius gayi was dominant and ubiquitous (occurrence, 95% of 9104 hauls), being the most vulnerable species of the bycatch. Three assemblages were identified: assemblage 1 (~200 m deep), dominated by flounders Hippoglossina macrops and lemon crabs Platymera gaudichaudii, assemblage 2 (~260 m deep), dominated by squat lobsters Pleuroncodes monodon and Cervimunida johni and assemblage 3 (~320 m depth), dominated by grenadiers Coelorinchus aconcagua and cardinalfish Epigonus crassicaudus. These assemblages were segregated by depth, and varied by year, and geographic zone. The latter represented changes in the width of the continental shelf, increasing southward of 36°S. Alpha-diversity indexes (richness, Shannon, Simpson, and Pielou) also varied with depth and latitude, with higher diversity in deeper continental waters (>300 m), between 2018-2019. Finally, at a spatial scale of tens of kilometres, and a monthly basis, interannual variations of biodiversity occurred in the demersal community. Surface sea temperature, chlorophyll-a, or wind stress did not correlate with discarded demersal fauna diversity of the crustacean fishery operating along central Chile.

Diet of the Dusky finless skate Gurgesiella furvescens (Chondrichthyes: Rajidae) from the continental shelf and slope of the north-central area of Chile

The dusky finless skate Gurgesiella furvescens appears sporadically as part of the bycatch in the trawl fishery targeting demersal crustaceans on the continental shelf and upper slope of the north-central area of Chile (26ºS-33ºS). Demersal crustaceans could be forage for deep-water predators such as G. furvescens, and sizes and shapes of prey eaten could be restricted by mouth size. The diet composition of G. furvescens was determined based on specimens collected from the bycatch of trawls targeting demersal crustaceans in 2013. Stomach contents revealed nylon shrimp Heterocarpus reedi (32.8% by weight), deep-water shrimp Haliporoides diomedeae (7.2% by weight), and indeterminate crustaceans (9.0% by weight). The diet composition was similar between sexes, body length, or depth strata. Prey size was a linear function of Gurgesiella furvescens mouth width, and prey mass positively related with G. furvescens individual mass. Although squat-lobsters Pleuroncodes monodon and Cervimunida johni were abundant in the study area, the nylon shrimp and deep-water shrimp in the diet of G. furvescens may be due to the preference or selection of this kind of prey in deep waters.

Distribution and biomass of anchovy (Engraulis ringens) and pelagic red squat lobster (Pleuroncodes monodon) in marine ecosystem of Paracas National Reserve, southern Peru

The present study determined the distribution and biomass of the Peruvian anchovy and pelagic red squat lobster related to the oceanographic characteristics in the marine protected area of the Paracas National Reserve in the Northern Humboldt Current System. Acoustic, biological, and oceanographic information was collected on the pelagic habitat in surveys carried out by the Peruvian Marine Research Institute during the summer and spring of 2018, 2019, and 2020. The results obtained indicated that the spatial occupation of the pelagic habitat of Peruvian anchovy and pelagic red squat lobster were influenced by the dynamics of upwelling, water masses, and a shallow and intense Oxygen Minimum Zone. Spatial overlap of high biomass of Peruvian anchovy and pelagic red squat lobster were recorded in the surface layer during the night. Although, with the presence of dense swarms of múnida in anoxic intermediate waters of the Oxygen Minimum Zone during the day. The Marine Protected Area off the Paracas National Reserve functions as a protection zone for the structure and functioning of the pelagic-neritic ecosystem and strengthens the fishery production of Peruvian anchovy stock in the Northern Humboldt Current System

Supercritical Fluid Extraction of Lipids and Astaxanthin Optimization from Munida (Pleuroncodes monodon) and its Characterization

ABSTRACT Munida (Pleuroncodes monodon) is a resource not economically exploited in Peru that contains important bioactive compounds such as astaxanthin (ASTX) and omega-3. A supercritical fluid extraction of lipids was performed using CO2 and ethanol, in order to maximize the ASTX extraction. Under optimal conditions, the lipid extraction was 22.53 g/100 g of munida meal, ASTX content of 5413.50 µg/g of munida lipid, omega-3 content of 31.79%, and shelf life of 71 days at 4°C Results provide key information about this resource for future utilization of food and pharmaceutical products.

Contrasting nursery habitats promote variations in the bioenergetic condition of juvenile female red squat lobsters (Pleuroncodes monodon) of the Southern Pacific Ocean.

The red squat lobster Pleuroncodes monodon is an important fishery resource in the Humboldt Current System (HCS). This decapod is exploited in two fishing units: (a) the northern fishing unit (NFU, from 26°S to 30°S) and (b) the southern fishing unit (SFU, from 32°S to 37°S), each of which have an adjacent nursery area that is the source of recruits to replace the exploited adult populations (in the NFU: off the coast of Coquimbo (28°S) and in the SFU: off the coast of Concepción (36°S)). Marked spatial differences in the environmental conditions of the NFU and SFU, and the biogeographic break that exists between these nursery areas (30°S) may promote changes in the bioenergetic condition of new P. monodon juveniles. To evaluate this, we analyzed the bioenergetic condition (measured as: body mass, lipids, proteins, glucose, and energy) of new juvenile females in the main nursery areas off the Chilean coast. The juvenile females from the SFU showed a higher body mass than those from the NFU. Consistently, the juvenile females from the SFU had a higher content of lipids, proteins, and glucose than those from the NFU, indicative of higher energy contents and a higher lipid/protein ratio in the south compared to the north. Considering the current overexploitation of this fishery resource in the HCS, it is essential to understand how the bioenergetic condition of juvenile females of P. monodon may vary in nursery areas at different latitudes in order to generate sustainable fishery management policies with an ecological approach, designed specifically to each fishing unit. Furthermore, identifying the latitudinal variations of these biochemical compounds in P. monodon juveniles can elucidate the geographic origin of red squat lobsters that present a ”better bioenergetic condition” in the HCS, which may significantly benefit sustainable fishing certification processes.

Feeding Habits of Sarda chiliensis chiliensis (Cuvier, 1832) in Northern Chile and Southern Perú.

Simple SummaryKnowing the biology of fish, preferably for this study of trophic relationships, is fundamental to advance in the culture technologies of this species, since knowing what they feed on will allow us to generate a species-specific food for the species and thus be able to obtain a fast and efficient growth. The objective of this research was to analyze the feeding habits of South Pacific bonito by sex and season between summer and autumn in three locations in the South Pacific, using trophic biology techniques. A total of 1404 stomachs were analyzed, corresponding to 420 specimens from the Pozo de Lisas area, 540 specimens from the La Capilla area and 444 specimens from the Chanavayita area. Dynamic indexes of feeding analysis and trophic composition of the diet were used. Under the analysis carried out in this research, we can conclude that fish feed more during autumn; in addition, the prey hierarchy of this species was Pleuroncodes monodon and Engraulis ringes. That said, and in view of the results, it would be a generalist species.The trophic relationships of pelagic fishes with migratory traits such as the South Pacific Bonito, Sarda chiliensis chiliensis (Cuvier, 1832), have not been studied in depth in the past. The objective of the present research was to analyze the feeding habits of South Pacific Bonito by sex and to analyze a comparison between summer and autumn months in three different areas of the eastern South Pacific by applying different techniques used in trophic biology. Between December 2013 and June 2014, specimens were captured in the areas of Pozo de Lisas (Ilo, Peru), La Capilla (Arica, Chile) and Chanavayita (Iquique, Chile). The feeding dynamics and trophic composition of the diet were analyzed, as well as the feeding strategy and trophic relationships. A total of 1404 specimens were analyzed, of which 654 had stomach contents. Seven prey items were identified: (a) fish remains; (b) squid jaw remains; (c) squid gladius remains; (d) caudal fin remains; (e) Engraulis rigens; (f) Pleuroncodes monodon and (g) N/A (not determined). The Pozo de Lisas and La Capilla areas showed homogeneity in their prey items, while the Chanavayita area showed more diversity. Regarding the importance of prey items in the diet of S. chiliensis in the three localities, it would be correct to state that it is a generalist species.

Toward a Solution of the “Peruvian Puzzle”: Pelagic Food-Web Structure and Trophic Interactions in the Northern Humboldt Current Upwelling System Off Peru

The northern Humboldt Current upwelling system (HCS) belongs to the most productive marine ecosystems, providing five to eight times higher fisheries landings per unit area than other coastal upwelling systems. To solve this “Peruvian puzzle”, to elucidate the pelagic food-web structure and to better understand trophic interactions in the HCS, a combined stable isotope and fatty acid trophic biomarker approach was adopted for key zooplankton taxa and higher trophic positions with an extensive spatial coverage from 8.5 to 16°S and a vertical range down to 1,000 m depth. A pronounced regional shift by up to ∼5‰ in the δ15N baseline of the food web occurred from North to South. Besides regional shifts, δ15N ratios of particulate organic matter (POM) also tended to increase with depth, with differences of up to 3.8‰ between surface waters and the oxygen minimum zone. In consequence, suspension-feeding zooplankton permanently residing at depth had up to ∼6‰ higher δ15N signals than surface-living species or diel vertical migrants. The comprehensive data set covered over 20 zooplankton taxa and indicated that three crustacean species usually are key in the zooplankton community, i.e., the copepods Calanus chilensis at the surface and Eucalanus inermis in the pronounced OMZ and the krill Euphausia mucronata, resulting in an overall low number of major trophic pathways toward anchovies. In addition, the semi-pelagic squat lobster Pleuroncodes monodon appears to play a key role in the benthic-pelagic coupling, as indicated by highest δ13C’ ratios of −14.7‰. If feeding on benthic resources and by diel vertical migration, they provide a unique pathway for returning carbon and energy from the seafloor to the epipelagic layer, increasing the food supply for pelagic fish. Overall, these mechanisms result in a very efficient food chain, channeling energy toward higher trophic positions and partially explaining the “Peruvian puzzle” of enormous fish production in the HCS.

Inter‐sexual comparison of body biomass, proximate biochemical composition, and fatty acid profiles of new juvenile squat lobsters (Pleuroncodes monodon) in the Southeast Pacific Ocean

AbstractIn 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.

Coping with El Niño: phenotypic flexibility of reproductive traits in red squat lobster determines recruitment success

Abstract Many organisms display changes in behaviour and life-history traits when facing variabilities in environmental conditions. A subset of these changes comprises reversible within-individual variations, known as phenotypic flexibility. Using red squat lobster (Pleuroncodes monodon) individuals harvested at the Humboldt Current Ecosystem (HCE), we evaluated how changes in habitat temperatures associated with warm El Niño (EN) conditions and cold La Niña conditions induce phenotypic flexibility in reproductive traits and how this flexibility affects recruitment success. The biological data were obtained from swept area surveys conducted between 2015 and 2020. Remotely sensed sea surface temperature (SST) data were used to compute anomalies (SSTA). Our results showed that females facing warmer environmental conditions carried more eggs with smaller sizes, and under cold conditions, females carried fewer eggs with larger sizes. The recruitments lagged by 1 year correlated positively with the egg density and negatively with the egg size. Our evidence shows that for phenotypic flexibility to be expressed in recruitment success, the warm conditions experienced by females should match good food availability for the planktonic stages. We discussed how climate change predictions for HCE will amplify responses of the reproductive traits of red squat lobster with strong impacts on recruitment likely.

Trophodynamics of the jumbo squid Dosidicus gigas during winter in the Southeast Pacific Ocean off the coast of Chile: Diet analyses and fatty acid profile

Marine trophodynamic studies have been developed mainly through the evaluation of stomach contents. However, these studies only reflect the feeding of a few days, showing a "snapshot" of the food consumed for a short time. Currently, new complementary techniques have been developed to evaluate the diet of predators using biochemical markers (fatty acids, FAs) and can, in turn, consider the rate of renewal of these biochemical constituents in body tissues. In the jumbo squid Dosidicus gigas, an important fishery resource in the Humboldt Current System, we identified and analyzed the stomach contents (prey) of D. gigas collected along the coasts of Chile in order to compare the FA profiles of its prey with those of three of its principal tissues and/or organs (digestive gland, gonad and mantle muscle). The analyses of the stomach contents indicate that D. gigas feeds on fish, crustaceans and squids, as previously have been reported. Regarding the FAs, the digestive gland presented the highest concentration and diversity of FAs, followed by the gonad and then the mantle. In turn, when comparing the FAs of the digestive gland of D. gigas with the FA profiles of its preys, the crustacean Pleuroncodes monodon and the fish Lampanyctus sp. presented the closest similarity, especially with a high contribution of essential FAs and PUFAs. Our findings indicate that during the cold season (austral winter), individuals of D. gigas may present an energy optimization strategy, characterized by the intake of prey with a high energy content rich in PUFAs, such as crustaceans and small fishes. This study not only contributes to the understanding of the squid biology and their trophodynamic, but also has important implications to improve fishery management within an ecosystem approach. This is relevant because D. gigas and its prey have suffered heavy exploitation, with a significant reduction in their biomass.

A switch in species dominance of a recovering pelagic ecosystem

Although many marine ecosystems have been adversely impacted by human activities,1 some are now recovering due to reductions in fishing pressure.2-4 Here, we document the recovery of an ecosystem subjected to intense anthropogenic activity for over 200 years, the Clyde Sea.5 This region once had productive fisheries for herring (Clupea harengus) and other fish, but these disappeared at the turn of the century.6,7 Using acoustic surveys of the pelagic ecosystem, we found that the Clyde Sea supports 100 times as many forage fish as in the late 1980s. However, herring has now been replaced by sprat (Sprattus sprattus), despite virtually no fishing on herring for 20 years. A combination of a warming sea,6 bycatch of herring in the prawn (Nephrops norvegicus) fishery,8,9 and susceptibility of herring to poor recruitment may have contributed to this unexpected recovery. We compare this to similar unexpected "recoveries" involving unforeseen ecosystem effects, such as the return of hake (Merluccius merluccius) to the North Sea;10,11 the recent expansion of the pelagic squat lobster, "munida," (Pleuroncodes monodon) off Peru;12 and the increase in scallop (Placopecten magellanicus) numbers on Georges Bank.13 The lack of a current sprat fishery in the Clyde presents a unique opportunity to develop an alternative industry for its seafaring community: ecotourism. Charismatic megafauna (whales, dolphins, and seabirds) that people will pay to see14 will, in time-if not already15,16-be drawn in by the abundance of forage fish now present, further restoring the biodiversity of the region after centuries of overexploitation.

Latitudinal changes in the lipid content and fatty acid profiles of juvenile female red squat lobsters (Pleuroncodes monodon) in breeding areas of the Humboldt Current System.

The red squat lobster Pleuroncodes monodon is a species of high commercial value that inhabits the Humboldt Current System. Along the Chilean coast, two populations are exploited by the fishing industry, one located off the coast of Coquimbo and the other off the coast of Concepción. Yet, it is unknown whether there are differences in the “bioenergetic fuel” (measured as lipid content and fatty acid profile) of juvenile populations of these two fishing units and whether these bioenergetic compounds can be modulated by differences in the environmental parameters (such as temperature or chlorophyll-a) of their breeding areas. To shed some light on this, we measured the lipid content and fatty acid profiles of the viscera and muscle of juvenile female red squat lobsters from these two fishing units, specifically from breeding areas near long-exploited fishing grounds: a) the northern fishing unit (NFU, from 26°S to 30°S) and b) the southern fishing unit (SFU, from 32°S to 37°S). We found differences in the lipid content, fatty acid profiles, and ratios of saturated fatty acids (C16:0/C18:0) of juvenile females from these two locations. In addition, the essential fatty acids (DHA/EPA) found in the viscera versus the muscle of these lobsters varied significantly. Juvenile females from the SFU (i.e. Concepción) showed a higher lipid content compared to the juvenile females from the NFU (i.e. Coquimbo). Consistently, individuals from the SFU had a higher content of fatty acids, which also proved to be richer in saturated and monounsaturated fatty acids compared to those from the NFU. Our results are important for the fisheries in both areas because these juvenile populations are the source of new recruits for the adult populations that are exploited by the fishing industry. Our study also aids in determining which populations are healthier or of better quality in bioenergetic terms. Furthermore, increasing the incorporation of bioenergetic parameters in fishery models is essential for the recruitment and stock assessment within an ecosystem approach, since it allows for the evaluation of the nutritional condition of different fishing populations.

Diet composition of an opportunistic predator from an upwelling area in the Southeastern Pacific

AbstractThe aim of this study was to use scat analysis to analyse the dietary composition of the South American sea lion (SASL, Otaria byronia) over a short temporal scale and in different but closely located colonies in the Humboldt Current System of northern Chile. Scat samples were collected at Arica (18°34′S), Iquique (20°48′S) and Mejillones (23°04′S) during the summer (January to March) and winter (July) of 2015. A total of 16 595 individual prey items from nine species were found in 194 of the 215 scat samples. In general, squat lobster (Pleuroncodes monodon) was the most important prey item for the sea lion diet, both by number and according to the index of relative importance (%IRI), followed by anchovy (Engraulis ringens), which was the most frequent prey item in the scats and the most important by weight. Patagonian squid (Loligo gahi) ranked third in importance in the sea lion diet. However, some spatiotemporal variations in the consumption of prey were found. Squat lobster was the most important prey for sea lions in Arica and Iquique, while anchovy was the dominant prey in Mejillones. Regarding seasonal variation, squat lobster was more important in winter than in summer in the three localities, while anchovy was also more important during winter, except in Mejillones where the levels of consumption of this prey were similar in both seasons. These results show that SASL adjust their dietary preferences, modifying the contribution of different prey both spatially and temporally. Spatiotemporal variations in the SASL diet can be explained by temporal changes in the distribution and abundance of their prey.

Gonadal development of female red squat lobsters (Pleuroncodes monodon H Milne Edwards, 1837)

Pleuroncodes monodon is a species that supports a trawl fishery of demersal crustaceans in Chile. However, knowledge of its reproductive condition at the gonadal level is still unknown. For this reason, the present study used histological and macroscopic techniques to evaluate the gonadal development of red squat lobster females collected between 25°08′S and 36°58′S along the coast of continental Chile. The results indicated that these females exhibit group-synchronous gonadal development. In addition, each female of the species clearly showed synchrony between gonadal maturity and embryonic development, revealing that it is a multiple spawner, although its fecundity is indeterminate because the total number of broods produced during the reproductive season is still unknown. The estimated maturity ogive varied significantly between physiological and functional criteria. The implications of these observations are discussed.