Yellow Squat Lobster Research Articles

Reproductive strategy of yellow squat lobster (Cervimunida johni Porter, 1903): re-evaluating the maturity criteria

ABSTRACT Studying the basic biology of heavily fished marine species is essential to achieving conservation and sustainable exploitation. Yellow squat lobster (Cervimunida johni) is a demersal crustacean with a long fishing history in the Southeast Pacific. However, knowledge of its reproductive biology is still fragmented, and these traits have never been validated at the gonad level. In this context, we assessed the reproductive traits of this species for the first time based on gonadal development using data from a research survey conducted during 2018 off the Chilean coast. A total of 117 and 376 gonads were assessed based on histological and macroscopic analyses, respectively. The functional and effective criteria (a combination of functional and physiological maturity) were used to estimate the maturity ogives. Using a total of 113 females, fecundity (F) and relative fecundity (RF) at length were estimated using the autodiametric method. We determined that females of yellow squat lobster possess group-synchronous ovary development with indeterminate fecundity. Histological analysis revealed that 59% of non-ovigerous females had mature ovaries and were therefore misclassified as immature based on the functional criterion. Similarly, maturity ogives derived from the effective criterion were displaced to smaller sizes and varied significantly from those estimated using the functional criterion (P < 0.05). In addition, the effects of female size on F and RF were significant (P < 0.05). A warning on the use of functional criteria for assessing maturity status is issued, and the importance of adult females on the per capita contribution to population renewal in this crustacean species is discussed .

Catch efficiency of trawl nets used in surveys of the yellow squat lobster (Cervimunida johni) estimated by underwater filming records

Catch efficiency is an important index to relate observed density to the size of a population in the context of bottom trawl surveys. The estimation of catch efficiency is challenging because it involves independent measures of animals in the path of the bottom trawl. We estimated catch efficiency using an underwater camera system on three trawl fishing vessels used for estimating the density of the yellow squat lobster (Cervimunida johni) off central Chile. During 2015 and 2018, 54 hauls were analyzed, and a total of 20 h of filming were recorded. A total of 4,155 yellow squat lobster individuals were analyzed approaching the net in the path of the trawl, of which 2,330 (56%) were captured and 1,825 escaped underneath the groundrope. The median estimated ranges of catch efficiency varied between 0.81–0.90 for vessel 1, 0.15–0.72 for vessel 2 and 0–0.58 for vessel 3. According to a hierarchical generalized linear model (HGML), fishing vessels and mean depth of hauls showed significant differences in catch efficiency (p<0.05). The results were comparable with estimates available for other crustacean species, and differences among vessels can be associated with differences in rigging configurations. Discussion was focused on the processes affecting catch efficiency and how differential catchability among sampling vessels may bias the construction of spatially explicit density maps and further abundance estimates of yellow squat lobsters in Chile.

Influence of Growth and Recruitment Parameters in the Assessment and Management Variables of the Yellow Squat Lobster (Cervimunida johni)

Fitting length data in age-structured stock assessment is a common method for evaluating hard-to-age animals, such as crustaceans. Growth specification and the uncertainty in the stock recruitment relationship are key issues in length-based assessment models. We conducted sensitivity analyses to evaluate the impact of growth and recruitment parameters on the stock assessment and management variables of the yellow squat lobster (Cervimunida johni) caught off the Chilean coast. Nine different scenarios of the length at first capture ( L a = 1 ) and the coefficient of variation at age ( c v a ) were tested for six combinations of values for the steepness parameter (h) and the recruitment variance ( σ R 2 ). We also investigated the reliability of these estimates using an operating model. Our findings indicate that the parameter related to growth, L a = 1 , has the greatest impact on the assessment and management variables of this fishery resource, with c v a having a lesser effect. Recruitment and fishing mortality estimates were the main variables affected. Parameters h and σ R 2 did not profoundly impact the variables assessed. In addition, L a = 1 was the most biased estimated parameter. We discuss that the high influence of growth parameters is related to model structure, and thus implications for determination of the status of yellow squat lobster should be addressed in the future. We recommended developing simulation protocols for the selection of growth parameters when using an age-structured model with length observations, and we believe that our findings are relevant for all Chilean fisheries with a similar stock assessment framework.

Estimation of natural mortality in two demersal squat lobster species off Chile

AbstractNatural mortality (M) is a key parameter for understanding population dynamics, especially in relation to harvested populations. Direct observations ofMin crustaceans are scarce, due to the moulting process. Indirect methods to estimateMwith easier-to-obtain life history attributes are therefore used routinely. Given their theoretical background, we reviewed the applicability of these methods for crustaceans. We applied the selected methods to two crustacean species harvested in Chilean waters: the yellow squat lobster (Cervimunida johni) and red squat lobster (Pleuroncodes monodon). Uncertainty of eachMestimate was incorporated in the life history parameters that input into the indirect method (trait-error) and parameters defining the indirect method (coefficient-trait-error). Methods based on the relationship between total mortality and maximum age, or with different ages and based on life history theory were the most appropriate for crustaceans since they apply across taxa.Mestimates showed high variability between species, sexes and areas. Estimations ofMforC. johnivaried from 0.13 to 0.28 (year−1) for males and 0.17 to 0.51 (year−1) for females. ForP. monodonvalues for the north varied from 0.26 to 0.37 (year−1) for males and 0.24 to 0.45 (year−1) for females. In the south, values ofMwere higher for both males (0.43–0.68 year−1) and females (0.41–1.06 year−1). High variability in theMestimates was associated with the method and number of parameters, their uncertainty, theoretical background and probability distribution.Mestimates are not comparable, raising the need to propagate the uncertainty ofMinto the stock assessment of Chilean squat lobsters.

Using a spatio-temporal Bayesian approach to estimate the relative abundance index of yellow squat lobster (Cervimunida johni) off Chile

Estimating relative abundance indexes based on spatio-temporal variations in fishing effort has been one of the greatest challenges in fisheries sciences. Obtained from the catch per unit of effort (CPUE), such indexes are generally used within evaluation models as "relative" to the stock abundance. Herein, a Bayesian spatio-temporal model was used to obtain an index for yellow squat lobster (Cervimunida johni) between the III and IV regions of Chile based on CPUE data (Kg/h.a) from fishing logs. The spatial field was approximated by a GMRF using the SPDE method and posterior distributions of interest were approximated using the Integrated Nested Laplace Approximation (INLA). By taking into account the distributional assumption of the CPUE the proposed model showed a good fit to the observed data. The proposed method allowed obtaining a relative index of abundance which could be included within the classic stock assessment models.

Self-bonded composite films based on cellulose nanofibers and chitin nanocrystals as antifungal materials

Cellulose nanofibers and chitin nanocrystals, two main components of agricultural and aquacultural by-products, were obtained from blue agave and yellow squat lobster industrial residues. Cellulose nanofibers were obtained using high pressure homogenization, while chitin nanocrystals were obtained by hydrolysis in acid medium. Cellulose nanofibers and chitin nanocrystals were characterized by X-ray diffraction, Atomic Force Microscopy and Infrared spectroscopy. Self-bonded composite films with different composition were fabricated by hot pressing and their properties were evaluated. Antifungal activity of chitin nanocrystals was studied using a Cellometer® cell count device, mechanical properties at tension were measured with a universal testing machine, water vapor permeability was evaluated with a thermohygrometer and surface tension with sessile drop contact angle method. The addition of chitin nanocrystals reduced slightly the mechanical properties of the composite. Presence of chitin nanocrystals influenced the growth of Aspergillus sp fungus in the surface of the composites as expected.

Direct age determination by growth band counts of three commercially important crustacean species in Chile

Management of commercially important crustacean stocks has been hindered by the inability to directly determine individual age. A lack of comprehensive age information leads to poor understanding of life history schedules, difficulty in estimation of parameters necessary for modeling population dynamics, and uncertainty in the determination of appropriate harvest levels. This study applied a novel direct age determination method based on band counts to three Chilean crustacean species: red squat lobster (Pleuroncodes monodon), yellow squat lobster (Curvimunida johni), and nylon shrimp (Heterocarpus reedi) for the first time. The growth bands were observed and counted in the endocuticle layer in thin longitudinal sections of the meso-cardiac ossicles of the gastric mills in the two squat lobster species and in the eyestalks of the nylon shrimp. Comparison of growth band counts with independent estimates of age strongly suggests that the bands form annually, thus providing a direct and accurate method of age determination in all of the species examined. Sex-specific growth curves were produced and demonstrated that the females grow at a slower rate than the males in the three species. Size and age-at-sexual maturity were also estimated. Application of this technique to known-age individuals will be necessary to validate band counts as indicators of chronological age.

Assessing changes in the southern Humboldt in the 20th century using food web models

This paper assesses changes in the southern Humboldt system (33–39°S) in the 20th century by constructing and comparing food web models representing four historical periods: (i) lightly exploited (<1900s), (ii) altered by removal of marine mammals (1950), (iii) development of industrial fisheries (1992), and (iv) the more recent state (2005) when main stocks are fully or overexploited. Models are constructed with a standard structure in terms of functional groups using the Ecopath with Ecosim (EwE) software version 5.1. Model components include: the fisheries, cetaceans, sea lions, marine birds, cephalopods, large-sized pelagic fish (swordfish), medium-sized pelagic fish (e.g., horse mackerel, mackerel, and Pacific grenadier), small-sized pelagic fish (e.g., anchovy and Araucanian herring), demersal fish (e.g., Chilean hake, black conger-eel), benthic invertebrates (red squat lobster, yellow squat lobster, pink shrimp) and other groups such as zooplankton, phytoplankton and detritus. Input data are gathered from published and unpublished (grey) literature. Inter-model comparison is based on individual and community indicators obtained by means of network analysis. The biomasses of target species (with the exception of small pelagic fish) and top predators decrease in more recent models. Although predation mortality is the main cause of total mortality for the majority of the fish groups in all models, fishing mortality of target species is high in the 1992 and 2005 models. This has led to a decrease in the importance of predation removal of the most important fish stocks compared with fishing, which is found to assume the role of the main predator in the system in the more recent state. Changes in system energetics could have resulted in loss of productivity by increased flow to detritus. Prior to heavy fishing, long-living and high-trophic level species were abundant compared to the most recent models in which species with small body size, short life span and low trophic level dominate. These fishing-induced trends are in accordance with what is theoretically expected in stressed ecosystems and, if correct, the food web could now be more susceptible to external forcing and negative ecological interactions.

Caracterizacion de agregaciones de langostino colorado (Pleuroncodes monodon) y langostino amarillo (Cervimunida johni) mediante un sistema de filmacion remolcado

To characterize red squat lobster ( Pleuroncodes monodon ) and yellow squat lobster ( Cervimunida johni ) aggregations a towed video system was used to cover a seabed area in the Coquimbo region, Chile. The films were made in 2009 and 2010, at depths between 102 and 215 m. Estimated average densities of P. monodon and C. johni varied between 3 and 63 ind m -2 and between 0.2 and 2.8 ind m -2 , respectively. Mating couples of C. johni were observed on July 2009 (∼200 m depth). The results show that the towed video system is an effective means of recording specimens of both species, allowing both the quantitative characterization of the stock and the observation of the species behavior and habitat. The system has the potential for use in direct assessment of abundance and habitat characterization both biotic and abiotic.

Estimacion de la biomasa de langostino amarillo (Cervimunida johni), aplicando Modelo Lineal Generalizado a registros de captura por area barrida en la zona central de Chile

Changes in the annual density of the yellow squat lobster (Cervimunida johni) were modeled using a generalized linear model (GLM), using information obtained during direct stock assessment cruises carried out in central Chile (32°-38°S) between 1997 and 2009. The purpose of this approach was to minimize the effect of different sampling criteria and designs that have been used over time and to determine the factors explain in variations in the density of this resource. The above approach allowed estimating the expected value of the annual density for the biomass calculation through the method. By using the haul-to-haul records of catch per unit of the swept area (CPUA), it was possible to identify and measure the points of abundance and characterize the distribution and area occupied by the resource over time. The significant effects identified by the GLM were the year, zone, depth, and first-order annual interactions; which explained 43% of the residual deviance in the model. The main effects that explain the CPUA variations are the year and the year-zone interaction. The zone with the greatest average abundance was located between 32° and 34°S; the same was for the depth range <250 m. Within the period analyzed, the biomass of the population of this resource increased steadily until 2006, mainly in the northern zone of the study area, followed by a sharp reduction 2009, that is 75% compared to the maximum and results in a biomass of 11,000 ton.

Estimating yellow squat lobster (Cervimunida johni) biomass by applying a generalized linear model to catch records per swept area in central Chile

Changes in the annual density of the yellow squat lobster (Cervimunida johni) were modeled using a generalized linear model (GLM), using information obtained during direct stock assessment cruises carried out in central Chile (32°-38°S) between 1997 and 2009. The purpose of this approach was to minimize the effect of different sampling criteria and designs that have been used over time and to determine the factors explain in variations in the density of this resource. The above approach allowed estimating the expected value of the annual density for the biomass calculation through the “swept area” method. By using the haul-to-haul records of catch per unit of the swept area (CPUA), it was possible to identify and measure the points of abundance and characterize the distribution and area occupied by the resource over time. The significant effects identified by the GLM were the year, zone, depth, and first-order annual interactions; which explained 43% of the residual deviance in the model. The main effects that explain the CPUA variations are the year and the year-zone interaction. The zone with the greatest average abundance was located between 32° and 34°S; the same was for the depth range

Alternative codends to improve the size selectivity for nylon shrimp (Heterocarpus reedi) and yellow squat lobster (Cervimunida johni) off the Chilean coast

The size selectivity of alternative codends for nylon shrimp and yellow squat lobster was studied off the Chilean coast using the covered codend technique. Various mesh sizes (47 and 63 mm mesh opening) and shapes (diamond and square) in the codends were used. For both species, substituting the DM47 codend with the DM63 codend significantly increased 50% retention length (l50). The change of diamond (DM47) to square mesh (SM47) had a positive effect in size selectivity for nylon shrimp. For yellow squat lobster, no significant effect was observed when changing the diamond (DM63) to square mesh (SM63). Selectivity data were modeled by considering explanatory variables such as ‘codend catch weight’ and ‘vessel’. Increases in the catch significantly reduced the l50 for both species whereas the vessel factor was not significant. Finally, using the length at first maturity as a reference value, the authors concluded that the DM47 codend failed to protect the immature portion of either stock, thus the DM63 codend is recommended.

Caracterizacion de las tacticas de pesca en la pesqueria multiespecifica de crustaceos demersales en Chile

In multispecies fisheries, each fishing operation can be described by analyzing the catch composition, fishing location, and fishing gear used. Sets of fishing operations with similar characteristics have been usually defined as fishing tactics. The present work defines fishing tactics for the crustacean multispecies fishery (CMF) developed between 26o03’S and 38o28’S off Chile. The catch composition per fishing haul, as recorded by scientific observers in fishing a logbooks from 2007 to 2009, was used. During this period, 1599 fishing hauls containing 57 species were registered in total. After employing a principal component analysis to reduce the species composition dimension, an agglomerative hierarchical analysis was carried out over the retained components. Four fishing tactics were identified and analyzed: 1) effort directed to Heterocarpus reedi (red shrimp) over a wide latitudinal range, 2) effort focused on Cervimunida johni (yellow squat lobster) in a narrow latitude range and at shallower depths, 3) effort directed to Haliporoides diomedeae (red royal shrimp), with the deepest hauls, and 4) effort focused on Pleuroncodes monodon (red squat lobster) in shallower waters close to the coast. In the case of the CMF, the identification of fishing tactics is important for indicating catch intention and for constructing abundance indices using data derived from fishing a logbooks. The results are discussed in terms of characterizing the fishing tactics and how their designation allows obtaining less biased abundance indices.

Alternative codends to reduce bycatch in Chilean crustacean trawl fisheries

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 70 mm, 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.

Mathematical modelling on the drying process of yellow squat lobster ( Cervimunida jhoni) fishery waste for animal feed

The main objective of the current research was to study and model the air drying kinetics of yellow squat lobster ( Cervimunida johni) fishery waste. This study was carried out at temperatures from 50 to 90 °C, using five empirical equations (Newton, Henderson–Pabis, Modified Page, Wang–Singh) and a new model proposed in this study. The kinetic parameters k i = 1, 2, …, 5, for each model were temperature-dependent as evaluated using an Arrhenius-type equation. The empirical parameters n i = 1, 2, …, 4, did not show temperature dependence. The fit quality of models on experimental data were evaluated using three statistical tests, sum square errors, root mean square errors, and Chi-square. When comparing the experimental values with the calculated values, it was shown that the Modified Page equation presented the best fit quality, and represented an excellent tool for estimating the drying time of this material, thus leading to the first stage in the development and use of yellow squat lobster waste as a by-product of fishery for animal feed.

Selectividad por tamaño de las presas en merluza común (Merluccius gayi gayi), zona centro-sur de Chile (1992-1997)

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.

Modelo de optimización para el cálculo de la cuota de captura de langostino amarillo

This paper presents a nonlinear optimization model that use to establish an annual quota for the total allo- wable catch for managing the yellow squat lobster fishery. The proposed bioeconomic model maximizes the economic profits of the activity involved and, simultaneously, takes into account the long-term conservation of the resource by restricting catches and thereby assuring adequate biomass level in the future. The dynamic behavior of the population is incorporated through a single-specie logistic growth model. Parameters (e.g., growth rate, maximun population and ish eort) were estimated based on a sampling technique using historical biomass reports and fishing yields. The results obtained with this methodology are shown, as is their application in managing this particular fi shery in the north of Chile.

Factores que afectan las tasas de captura de langostino amarillo (Cervimunida johni) en la zona norte de Chile

An analysis was made of the factors affecting the catch rates of the yellow squat lobster (Cervimunida johni) in Chile's northern region (26°03'-32°10'S) by reviewing commercial fishing logbooks from 1993 to 2003. Factors evaluated included years, months, depth stratum, fishing areas and fleet characteristics as linear predictors in a generalized linear model (GLM) in order to explain variability in the catch rate. In contrast with other fisheries, with this resource the technical characteristics of the fleet and its' specialization poorly explain variations in catch rate; temporal factors and their interaction were, however, highly significant. The results of this study, together with the life history of the resource, allow the supposition that standardized catch rates are appropriate as an index of relative abundance in this fishery.

Trophic interactions and community structure in the upwelling system off Central Chile (33–39°S)

Trophic interactions and community structure in the upwelling system off Central Chile (USCCh) (33–39°S) are analyzed using biological and ecological data concerning the main trophic groups and the Ecopath with Ecosim software version 5.0 (EwE). The model encompasses the fisheries, cetaceans, sea lion, marine birds, cephalopods, large-sized pelagic fish (sword fish), medium-sized pelagic fish (horse mackerel, hoki), small-sized pelagic fish (anchovy, common sardine), demersal fish (e.g. Chilean hake, black conger-eel), benthic invertebrates (red squat lobster, yellow squat lobster) and other groups such as zooplankton, phytoplankton and detritus. Input data was gathered from published and unpublished reports and our own estimates. Trophic interactions, system indicators and food web attributes are calculated using network analysis routines included in EwE. Results indicate that trophic groups are aligned around four trophic levels (TL) with phytoplankton and detritus at the TL=1, while large-sized pelagic fish and cetaceans are top predators (TL>4.0). The fishery is located at an intermediate to low trophic level (TL=2.97), removing about 15% of the calculated system primary production. The pelagic realm dominates the system, with medium-sized pelagic fish as the main fish component in biomass, while small-sized pelagic fish dominate total landings. Chilean hake is by far the main demersal fish component in both, biomass and yield. Predators consume the greater part of the production of the most important fishery resources, particularly juvenile stages of Chilean hake. Consequently, mortality by predation is an important component of total mortality. However, fishery also removes a large fraction of common sardine, anchovy, horse mackerel, and Chilean hake. The analysis of direct and indirect trophic impacts reveals that Chilean hake is a highly cannibalistic species. Chilean hake is also an important predator on anchovy, common sardine, benthic invertebrates, and demersal fish. The fisheries heavily impact on Chilean hake, common sardine, anchovy, and horse mackerel. Total system biomass ( B=476 t km −2 year −1) and throughput ( T=89454 t km −2 year −1) estimated in the USCCh model are in accordance with models of comparable systems. Considering system attributes derived from network analysis, the USCCh can be characterized as an immature system, with short trophic chains and low trophic transfer efficiency. Finally, we suggest that trophic interactions should be considered in stock assessment and management programs in USCCh. In addition, future research programs should be carried out in order to understand the ecosystem effects of fishing and trophic control in this highly productive food web.