Seabob Shrimp Xiphopenaeus Kroyeri Research Articles

Marine and estuarine crustacean diversity and assemblage structure in eastern Brazil three years after the Fundão mining dam failure

The present study investigates the spatial and temporal patterns of species richness and assemblage structure of decapod and stomatopod crustaceans in the area impacted by the Fundão dam collapse (Rio Doce basin, Brazil) in November 2015. From October 2018 to September 2019, monthly bottom-trawl samples were collected in estuarine and marine waters of the Rio Doce (directly impacted area) and three other localities. Forty-one crustacean species were recorded, with the overall community structure dominated by six species. The seabob shrimp Xiphopenaeus kroyeri was the most common species, with the coastal marine area near to the Rio Doce mouth being an important fishery ground. Species composition changed significantly among localities, habitats, and seasons, with marine and estuarine assemblages shaped by freshwater discharge. Distribution patterns of species were significantly influenced by the environmental variables potentially altered by tailings, such as turbidity and pH. Species richness and abundance differed among localities; as expected, they were generally higher on the inner shelf than in estuaries and higher during the dry season than the rainy season. Due to the lack of information before the disaster, the low number of species found in the Rio Doce estuary cannot be solely attributed to the disaster but also its freshwater condition. This is the first broad study of the estuarine and coastal marine decapod and stomatopod crustaceans in the region, and we suggest the need for long-term monitoring considering that the effects of this disaster are not easy to detect and probably need multi-year study to be evidenced.

Ovarian morphology and oocyte development in the seabob shrimp Xiphopenaeus kroyeri: a histological and histochemical approach for the study of penaeid reproduction

Histological and histochemical changes during oocyte development were evaluated in order to establish a model for better understanding nutrient dynamics throughout vitellogenesis and overall penaeid reproduction. Samples of Xiphopenaeus kroyeri females (n = 587) at different stages of gonadal maturation were subjected to histological and histochemical analysis for the identification of neutral polysaccharides, total proteins, and tissue differentiation. We observed that the ovarian structure was composed of collagen fibers and oviducts were lined by three layers of epithelium separated by muscular tissue. Oogenesis was classified into six distinct phases: chromatin nucleolar oocytes, chromatin perinucleolar oocytes, oocytes in primary vitellogenesis, oocytes in secondary vitellogenesis, mature oocytes, and atretic oocytes. Histochemical observations suggested that during the previtellogenesis phase, proteins and neutral polysaccharides were not present. However, a progressive increase in these substances occurred from vitellogenic oocytes until their final maturation stage. Follicular cells composed the follicular complex forming an external epithelium in vitellogenic oocytes, and are probably involved in protein transfer during maturation process. Collagen and glycoprotein vesicles were identified in the cytoplasm of mature oocytes of X. kroyeri. Taken together, the present findings contribute to the current knowledge on the ovarian morphology and maturation process of penaeids, supporting future studies on reproductive biology and breeding performance in captivity.

Greenhouse gas emissions, consumption, and fuel use intensity by an artisanal double-rig trawl fleet in southern Brazil

In Brazil, most national marine production is captured by artisanal fisheries. The present study was conducted in a traditional trawl fishing area for the capture of the Atlantic seabob shrimp Xiphopenaeus kroyeri in southern Brazil between 1996 and 2015 to obtain initial estimates of direct fuel inputs and greenhouse gas emissions. The data includes vessel characteristics, total and seabob shrimp production, and trawl duration. Approximately four million liters of fuel were consumed for an estimated catch of around 148,000 kg of fish (26.4 liters/kg captured), of which 19,000 kg were seabob shrimp (206 liters/kg captured) or 13% of total production. The carbon emitted by this fleet was almost three million GgC, between 401 and 666 tons per year. Although the number of vessels has increased over the years, catches, especially of seabob shrimp, have declined sharply, indicating over-exploitation of this resource, and reinforcing the urgent need to create management programs and selective technologies for this modality.

Atlantic seabob shrimp as biomonitor of Cu and Zn near port activities: is it really a suitable choice?

The trace elements concentration in the muscle of the Atlantic seabob shrimp (Xiphopenaeus kroyeri) caught in coastal fishing highlighted copper (Cu) and zinc (Zn), both related to antifouling systems, as the main elements related to the intensity of port activities of southeast Brazil (~20—to 22ºS). The aim of this study is to analyze if the behavior of Cu and Zn in the muscle of this shrimp species is constant among different sampling sites, verifying if the species is suitable as biomonitor for these elements. The shrimps came from fisheries done in 2017 in Vitória, Anchieta, and Farol de São Tomé, southeast Brazil. After sampling, each individual was categorized for gender and maturity stage, measured, and weighted. Bulk muscle samples were freeze-dried for determination of Cu, Zn, and ratios of stable isotopes of carbon (δ13C) and nitrogen (δ15N). The data analysis verified if the concentration of Cu and Zn in male and female shrimps vary among maturity stages and sampling sites, and how the concentration of Cu and Zn is related to shrimps foraging area and/or trophic position. Both bioaccumulation and growth dilution occurred, but not in the same way for genders and sampling sites, with Cu showing more variability. Relationships between elements and shrimps foraging area and trophic position did not show a clear trend among the sampling sites. Regression models indicated moderate relationships, explaining 51% (Cu) and 60% (Zn) of the association with the foraging area in Anchieta, but up to 8% in Vitória and Farol de São Thomé. For the trophic position, the models explained 33% (Cu) and 34% (Zn) in Anchieta and up to 14% in Vitória and Farol de São Thomé. The results showed that the utilization of this shrimp species as biomonitor of marine coastal environments near port activities to monitoring the levels of Cu and Zn is not a suitable choice, at least in the spatial scale considered by this study.

Trace elements in commercial shrimps caught near port activities in SW Atlantic Ocean and human health risk assessment on consumption

This study presents the concentration of trace elements in commercial shrimps caught in coastal fishing areas near large port activities of southeast Brazil (∼20°S–22°S), SW Atlantic Ocean. The seabob shrimp Xiphopenaeus kroyeri and the Argentine stiletto shrimp Artemesia longinaris were sampled in 2017, and the trace elements were determined in the muscle (edible portion). For all sampling sites (Vitória, Anchieta and Farol de São Thomé), the highest concentrations were Al > Fe > Zn > As > Cu, followed by Pb, V, Ni, Cr, Cd and Sn in lower concentrations. Only Zn and Cu were related to the intensity of port activities. According to the maximum permissible limits for trace elements established by the Brazilian Government for fishery products, the estimated daily intake and the maximum safe daily consumption rate, the edible portion of the two shrimp species does not present risk for human health.

Mollusk bycatch in trawl fisheries targeting the Atlantic seabob shrimp Xiphopenaeus kroyeri on the coast of Sergipe, northeastern Brazil

The malacofauna bycatch of sea-bob shrimp Xiphopenaeus kroyeri (Heller, 1862) trawl fisheries on the coast of Sergipe was studied for 5 years. The malacofauna bycatch considered was obtained in nine oceanographic sampling campaigns carried out between May 1999 and June 2003 in 18 stations distributed in six transects along depths of 10, 20 and 30 m. A total of 2,669 individuals of mollusk belonging to 54 species were captured on the 18 sea-bob shrimp trawl stations carried out along the coast of Sergipe. The considerable richness of mollusks was composed by 19 families and 31 species of gastropods, 12 families and 19 species of bivalves and 2 families and 4 species of cephalopods. The highest abundance were observed at stations 13 (373 individuals) and 16 (685 individuals) that represents the lowest depth (10 m) and the richness was higher at stations 15 and 12 (17 and 11 species, respectively) both located at the highest depth (30 m). Cephalopods had high frequency of occurrence being collected in all the stations and by far the most abundant group with a total of 2,488 individuals captured. On the other hand, gastropods (with 142 individuals found in 83.3% of stations) and bivalves (about 1% of the individuals collected) contribute with a much smaller percentage of individuals captured. Lolliguncula brevis (Blainville, 1823) was most representative cephalopod in number and frequency of occurrence. Arcidae, Conidae, Muricidae and Strombidae were the families with the higher number of species in the trawl-fishery. Among bivalves, Pitar arestus (Dall & Simpson, 1901) and Spathochlamys benedicti (Verrill & Bush [in Verrill], 1897) were the species with higher frequency of occurrence. Although the considerable sample effort and a number of mollusks captured as bycath, the richness estimators indicated that the species richness could increase with additional sampling effort in the study area. The present study expands the taxonomic alpha knowledge on the mollusk bycatch of sea-bob shrimp trawl fisheries on the northeastern coast of Brazil. However, it is of crucial importance to assess urgently the negative impacts of the sea-bob shrimp trawl fisheries on the benthic community of the entire coast of Brazil.

The crustacean bycatch of seabob shrimp Xiphopenaeus kroyeri (Heller, 1862) fisheries in the Cananéia region, southern coast of São Paulo, Brazil

The bycatch of shrimp fisheries is highly diverse, but still understudied in the coast of Cananéia (São Paulo, Brazil), where shrimp fisheries are very intensive. Aiming to fill this gap, we analysed the diversity of crustaceans in the bycatch of seabob shrimp (Xiphopenaeus kroyeri) fisheries. Samplings were taken monthly, from March 2013 to May 2014, using a shrimp bottom trawling net aboard a commercial vessel. The crustacean bycatch encompassed 22 families, 36 genera and 46 species. The families with the highest species richness were Portunidae (8 species) and Penaeidae (5 species), corresponding to 17.4% and 10.9%, respectively, of all species caught. Overall, the abundance of X. kroyeri was higher than that of the crustacean bycatch except during in December 2013-February 2014, when the ratio was nearly 1:1 (Binomial test, p <0.05). There was a great variation in the abundance of crustaceans throughout the year, and the highest proportion of bycatch occurred outside the period when the fishery is forbidden. We provide evidence that the trawling in Cananéia captures a great diversity of crustaceans that coexist with the target shrimp species.

Isolation and characterisation of 14 novel microsatellite markers through Next Generation Sequencing for the commercial Atlantic seabob shrimp Xiphopenaeus kroyeri.

Assessing population genetic structure is a crucial step to support fisheries and conservation management. DNA microsatellite molecular markers are a widely used tool in population genotyping. In the present study, we characterised and developed 14 novel polymorphic microsatellite markers for a decapod crustacean, the Atlantic seabob shrimp Xiphopenaeus kroyeri (Heller, 1862), through rapid and cost-effective Illumina shotgun sequencing and a Galaxy-based bioinformatic pipeline. We genotyped 60 individuals from 2 populations with the newly developed microsatellites, resulting in the detection of 3 to 29 alleles per locus. Four loci deviated from Hardy-Weinberg equilibrium. Cross-amplification in a cryptic congeneric species was successful for eight loci (57%). The microsatellite loci developed in this study will be highly relevant for genetic and evolutionary studies of X. kroyeri, and for the stock management of this commercially exploited species.

Effect of carbon dioxide-induced water acidification and seasonality on the physiology of the sea-bob shrimp Xiphopenaeus kroyeri (Decapoda, Penaeidae)

AbstractClimate changes are altering the chemistry of the oceans, and knowing their effects on the biology of animals is urgent. Since the physiological responses of crustaceans may be different given the seasons of the year, this work evaluated the synergistic effect of ocean acidification and seasonality on the physiology of the sea-bob shrimp,Xiphopenaeus kroyeri. Experimental groups were exposed for 5 days to two levels of pH, representing present-day mean ambient conditions (pH 8.0) and distant-future conditions (pH 7.3) during the summer and winter. Metabolism, nitrogen excretion, energy type and storage were determined, respectively, by oxygen consumption, ammonia excretion, atomic ratio O/N and hepatosomatic index. The reduction of pH resulted in a decrease of about 30% in theX. kroyerimetabolism during the summer and winter. Nitrogen excretion (reduction of 40%) and hepatosomatic index (increase of 120%) showed to be altered in animals exposed to reduced pH only throughout summer. Regardless of pH and seasons of the year, animals use mainly proteins as energy substrate and they do not show mortality. The increase of the hepatosomatic index, indicator of the accumulation of energy reserves, associated with metabolism reduction, suggests the suppression of activities that demand energy expenditure. The consequences of the physiological alterations observed may include decreases in growth and reproduction rate and displacement of populations to more appropriate conditions. The results might be associated with a set of factors resulting from the exposure to reduced pH, the synergy between pH and temperature, but also with a pattern of different physiological responses that may occur according to seasonality.

Reproductive cycle of seabob shrimp Xiphopenaeus kroyeri (Crustacea, Penaeidea) from the northeast coast of Brazil

The reproductive cycle of Xiphopenaeus kroyeri north-eastern Brazil was described to contribute to the sustainable management of this stock in the region. Specimens were collected monthly from August 2011 to July 2012 using a local vessel of the artisanal fleet. A total of 1201 individuals were analyzed (673 females and 528 males) with a mean carapace length (CL) of 1.88 ± 0.16 cm and total length (TL) of 9.00 ± 1.22 cm. The lowest CL and TL of mature females were 1.33 and 6.5 cm, respectively, and all females above 2.44 cm (CL) and 11.5 cm (TL) were mature. Ovarian maturation was classified into four stages: I (immature), II (maturing), III (mature) and IV (spawned). Individuals of all maturational stages were present throughout the year. Considering the macro and microscopic analysis, it was suggested that this species in north-eastern Brazil has a continuous reproductive cycle, with two seasonal peaks, November/December and February (austral spring and summer). A positive correlation between the percentage of mature females and temperature was observed, and a higher percentage was reported in the warmer months of the year. This suggests that the reproductive peaks can be triggered by water temperature variation throughout the year.

Does the upwelling phenomenon influence the population dynamics and management of the seabob shrimp Xiphopenaeus kroyeri (Heller, 1862) (Crustacea, Penaeidae)?

The seabob shrimp Xiphopenaeus kroyeri ranks third in commercial importance among fisheries in southeastern Brazil. An important management question is whether the same offseason can be applied to different regions. The population dynamics of the seabob shrimp was compared in two regions of southeastern Brazil: Macae, state of Rio de Janeiro and Ubatuba, state of Sao Paulo. All demographic categories of shrimp in the Macae region were larger than those in the Ubatuba region. Lower temperatures and greater longevities in the Macae region may account for this difference in size from Ubatuba. In Macae, number of reproductive females and juveniles correlated with organic-matter content. In Ubatuba, only chlorophyll-a showed a correlation with reproductive females. The reproductive period and recruitment were correlated in both populations. The difference in environmental factors between these regions, resulting of the Cabo Frio upwelling, although they are located close together, directly influences the population dynamics of X. kroyeri. The Cabo Frio upwelling may be acting as a physical barrier, preventing gene flow and differentiating the seabob shrimp stocks in the two regions. These data suggest that different offseason periods for different regions could increase the sustainability of shrimp harvesting along the Brazilian coast.

Trophic ecology of Atlantic seabob shrimp Xiphopenaeus kroyeri: Intertidal benthic microalgae support the subtidal food web off Suriname

A combination of stomach content analyses and dual stable isotope analyses was used to reveal the trophic ecology of Atlantic seabob shrimp Xiphopenaeus kroyeri off the coast of Suriname. This coastal penaeid shrimp species has a rather omnivorous diet, feeding opportunistically on both animal prey and primary food sources. The species is a predator of hyperbenthic crustaceans, including copepods, amphipods and the luciferid shrimp Lucifer faxoni, which are mainly preyed upon during daytime, when these prey typically reside near the seabed. Benthic microalgae (BM) from intertidal mudflats and offshore sedimentary organic matter (SOM) were important primary food sources. Due to their depleted 13C values, coastal sedimentary and suspended organic matter, and carbon from riverine and mangrove-derived detritus were not incorporated by X. kroyeri. An ontogenetic diet shift was observed from postlavae to juveniles and adults. Adult X. kroyeri were located higher in the food chain, mainly preying on larger benthic organisms. Intertidal BM were an important food source for all life stages of X. kroyeri, contributing up to 64% to the overall diet based on a Bayesian mixing model. Because X. kroyeri is the main epibenthic organism found at high densities in nearshore waters up to 30 m depth, the species plays a crucial role in transferring energy from low trophic level prey and primary food sources up to higher levels in the food chain. Our results indicate that primary production on intertidal mudflats, through BM, forms an important energy source for the subtidal turbid-water food web in muddy tropical coasts. Conservation of intertidal areas and their associated mangrove systems will therefore likely benefit coastal shrimp production and fisheries in tropical ecosystems.

Damage and mortality of juvenile seabob shrimp (Xiphopenaeus kroyeri) discarded in a tropical artisanal trawl fishery

Abstract In response to concerns over wastage and negative impacts on stocks, the damage (antennae loss) and collateral mortality of artisanally trawled-and-discarded juvenile seabob shrimp (Xiphopenaeus kroyeri) and the key factors explaining variability were assessed in the South Brazil Bight. During 20 deployments across 7 d of fishing, 1562 X. kroyeri (14.5 ± 3.1 mm carapace length, CL) were discarded into replicate on-board tanks at both the start and end of sorting, with some individuals monitored immediately for antennae loss and mortalities, and the rest assessed after 3 h. Virtually, all X. kroyeri discarded towards the end of sorting (mean ± SD air exposure of 15.9 ± 3.9 min) died. By comparison, those discarded at the start (2.7 ± 2.8 min) had variable temporal mortalities (total of 52.3% immediately vs. 66.2% after 3 h) which, like antennae loss (total mean ± SE of 50.4 ± 34.2%) were positively associated with haul duration/catch weight and deck exposure, and more frequent among individuals with soft than hard exoskeletons. Antennae loss was also negatively correlated with CL. The results support (i) improving trawl selectivity to reduce the catches of small, unwanted X. kroyeri and other bycatch (and therefore total weights of catches) and/or (ii) sorting catches in water (to minimize air exposure). Such modifications might be promoted through awareness of the potential harvest benefits to fishers associated with reducing unaccounted fishing mortality of the targeted species.

Local hydrography and fishing drive life cycle strategies and population dynamics of the sea-bob shrimp Xiphopenaeus kroyeri in a coastal subtropical environment in Brazil

The sea-bob shrimp is a shallow-water species whose population dynamics along the southern and southeastern coasts of Brazil is influenced by the upwelling of the South Atlantic Central Water (SACW). Since the SACW does not reach our study area, we hypothesize that life cycle and distribution patterns are dominated by the local regime of estuarine plumes. Also, we would expect higher biomasses and larger individuals in autumn due to the closed fishing season. We conducted a survey for a year, consisting of 20 monthly trawling hauls. Spawning peaks occurred in spring and autumn, related to rainy periods with greater estuarine loads of particulate material and phytoplankton production. The relative abundance of larger individuals increased with depth, while juveniles concentrated at shallower sites. Size classes prior to the closed season were affected by increased fishing during summer due to tourist demand. Water transparency and bottom temperature were the main factors controlling the distribution and life cycle of sea-bob shrimp. Seasonal changes in biomass could be related to the inshore–offshore migrations of the type-3 life cycle, compounded by the impacts of fishing. Thus, fishing and local hydrography can drive life cycle and distribution patterns of the species, with important management implications.

Temporal variations in biomass and size of seabob shrimp Xiphopenaeus kroyeri (Heller, 1862) (Decapoda: Penaeoidea) on the southern coast of São Paulo state, Brazil

Abstract Xiphopenaeus kroyeri (Heller, 1862) is the third most common species caught by fishing boats in the state of Sao Paulo, Brazil and production of this shrimp in the Cananeia region located on the southern coast of this state ranks second in the nation. The aim of this study was to investigate the temporal variation of the total biomass and size of X. kroyeri and analyze this variation against environmental factors in order to suggest some information about the best periods to fish this species. Samples were caught monthly from four sampling stations in Cananeia between July 2012 and June 2014 using a fishing boat equipped with otter-trawl nets. Temperature and salinity were monitored using a multiparameter probe, and sediment samples were also taken using a Van Veen-type gripper for particle size analysis. The shrimp were weighed, quantified, and carapace length was measured (mm). In general, the highest total biomass values were recorded when the fishery was closed in the southeast and south regions, and the highest catch of smaller individuals was also observed during this period. In contrast, in November 2013 the fishing is permitted and high biomass composed of large individuals was observed. The monthly biomass showed a positive relationship with sediment texture, because this species prefers very fine sediments to burrow as a defense against predators.

Distribution patterns of the demersal fish fauna on the inner continental shelf of Suriname

This study aimed to characterise the spatio-temporal patterns of the demersal fish community in the shallow (<40 m) inner shelf waters of Suriname, based on (bi)monthly data for the period February 2012–April 2013. From 148 demersal trawl samples, distributed over 15 locations, 98 fish species were identified. Stellifer rastrifer, Amphiarius rugispinis and Cynoscion jamaicensis represented 50 % of the catches. Cluster analysis revealed three species assemblages, occurring in a nearshore–offshore depth gradient. A coastal fish assemblage occurred in the shallow turbid waters, characterised by muddy sediments with relatively high organic carbon content. A transition assemblage around 27 m water depth marked the shift towards a very different offshore fish assemblage on the deepest sampling locations (34 m), which were characterised by coarser sediments, with clear overlying waters. The coastal assemblage represented the ‘sciaenid community’ of tropical shelves, dominated by Sciaenidae and Ariidae. The offshore assemblage had a significantly lower fish density and diversity, and contained representatives of fish families typical for deeper tropical shelves, such as Paralichthyidae, Triglidae and Lutjanidae. The shift between the coastal and offshore fish assemblage was the most important feature of the demersal fish community, and coincided with a transition between two principal ecosystems: a coastal, river influenced system fuelled by detritus versus an open shelf system based on primary production. Whereas pelagic fishes are known to gain in importance on the open shelf, demersal fishes thrived in the coastal ecosystem, together with a potentially important epibenthic food source, the Atlantic seabob shrimp Xiphopenaeus kroyeri. In Suriname, large demersal (mainly sciaenid) fishes are the main fisheries resource for the artisanal fleet in the nearshore waters below 20 m depth. Because juveniles of commercially important fishes were abundant in our coastal trawl catches, we suggest the shallow nearshore waters have a main nursery function.

Spatio-temporal distribution patterns of the epibenthic community in the coastal waters of Suriname

This study aimed to characterize the spatio-temporal patterns of the epibenthic community in the coastal waters of Suriname. Data were collected on a (bi)monthly basis in 2012–2013 at 15 locations in the shallow (<40m) coastal area, revealing three spatially distinct species assemblages, related to clear gradients in some environmental parameters. A species-poor coastal assemblage was discerned within the muddy, turbid-water zone (6–20m depth), dominated by Atlantic seabob shrimp Xiphopenaeus kroyeri (Crustacea: Penaeoidea). Near the 30m isobath, sediments were much coarser (median grain size on average 345±103µm vs. 128±53µm in the coastal assemblage) and water transparency was much higher (on average 7.6±3.5m vs. 2.4±2.1m in the coastal assemblage). In this zone, a diverse offshore assemblage was found, characterized by brittle stars (mainly Ophioderma brevispina and Ophiolepis elegans) and a variety of crabs, sea stars and hermit crabs. In between both zones, a transition assemblage was noted, with epibenthic species typically found in either the coastal or offshore assemblages, but mainly characterized by the absence of X. kroyeri. Although the epibenthic community was primarily structured in an on-offshore gradient related to depth, sediment grain size and sediment total organic carbon content, a longitudinal (west-east) gradient was apparent as well. The zones in the eastern part of the Suriname coastal shelf seemed to be more widely stretched along the on-offshore gradient. Although clear seasonal differences were noted in the environmental characteristics (e.g. dry vs. rainy season), this was not reflected in the epibenthic community structure. X. kroyeri reached very high densities (up to 1383ind1000m−²) in the shallow coastal waters of Suriname. As X. kroyeri is increasingly exploited throughout its range, the current study provides the ecological context for its presence and abundance, which is crucial for an ecosystem approach and the sustainable management of this commercially important species and its habitat.

Reproductive ecology of the seabob shrimp Xiphopenaeus kroyeri (Heller, 1862) in a coastal area of Southern Brazil

The predictability of certain environmental factors that affect the life cycle of the seabob shrimp Xiphopenaeus kroyeri (Heller, 1862) was evaluated in a study of its reproductive biology in an area adjacent to Babitonga Bay, State of Santa Catarina, Brazil. Monthly sampling was conducted from July 2010 through June 2011 at depths of 5, 8, 11, 14, and 17 m. 76 004 individuals were obtained, with a pronounced peak in absolute abundance in austral autumn (34 208), coinciding with the annual closed season from March to May. Grain size composition of the sediment showed the closest relationship to the distribution of individuals (multiple linear regression, P <0.05), related to their burying habit. The observed correlations between the abundance of reproductive males (bearing spermatophores) and females with spent gonads (cross-correlation, P <0.05), and between reproductive males and reproductive females (with a 1-month lag) suggest that the peak of reproductive males preceded the peak of female ones. This result agrees with the pattern expected for females, which copulate in post-ecdysis (spent gonads). Spawning seemed to take place at greater depths, as evidenced by the concentration of reproductive females in these areas. The reproductive activities observed here confirm that this species follows a tropical/subtropical reproductive pattern, spawning continuously throughout the year, with the highest peaks in spring and autumn. The data indicate that the juvenile recruitment period observed in August-September resulted from the reproductive output noted in April–May. Additionally, the reproductive period recorded in November led to the juvenile peak observed in March–May.

Bycatch fauna of seabob shrimp trawl fisheries from Santa Catarina State, southern Brazil

Marine communities in tropical regions contain a great diversity of species that play key roles in ecological processes. The observed bycatch fauna in artisanal fishing for the seabob shrimp Xiphopenaeus kroyeri (Heller, 1862) in the southwest Atlantic exceeds the quantity of commercial shrimp captured. This bycatch has not been previously inventoried extensively in Brazil, particularly in the State of Santa Catarina, where small-scale shrimp fisheries is a traditional activity and dominates the local fishing economy. Six municipalities were sampled three times a month, from 1996 to 2011, yielding 216 species belonging to the bycatch (7 cnidarians, 22 mollusks, 42 crustaceans, 11 echinoderms, and 134 fishes). Bycatch management is a pressing aspect of shrimp fisheries. By inventorying the accidental bycatch, we provide a preliminary step towards defining intervention measures to reduce or make better use of this bycatch in seabob artisanal fisheries. Conservation of marine biodiversity is still inadequate in Brazil. We have attempted to identify additional threats to vulnerable and endangered species resulting from shrimp trawling.

Lifespan and reproductive dynamics of the commercially important sea bob shrimp Xiphopenaeus kroyeri (Penaeoidea): synthesis of a 5-year study

Population parameters of the shrimp Xiphopenaeus kroyeri (Heller, 1862) (sex ratio, length-frequency distributions (carapace length, CL), growth, lifespan, size of sexual maturity, spawning and recruitment) were analyzed in a long-term study from January 1998 through June 2003. The data on these parameters were collected and analyzed to test the hypothesis that the main period of juvenile recruitment in the bay coincides with the period of fishery closures currently designated by the Brazilian Institute of Environment and Renewable Natural Resources. Monthly collections were conducted along the southeastern Brazilian coast, using a shrimp fishing boat with “double-rig” nets sampling at stations up to 40 m depth. Sex ratios were female-biased only in zones with high reproductive activity such as in stations deeper than 15 m (χ2 test, p<0.05). The mean size of males and females was 15.3 ± 3.1 mm CL and 16.2 ± 4.7 mm CL, respectively, with size at sexual maturity estimates (CL50) of 14.8 mm for males and 15.5 mm for females. Mean growth curves provided estimates of CL∞ = 29.31 mm, k = 0.009/day, t0=−0.25 and CL∞ = 35.33 mm, k = 0.006/day, t0=−0.23 for males and females, respectively, and average lifespans of 1.35 for males and 2.12 years for females. Recruitment and abundances of reproductive females were highly correlated with the environmental factors such as higher water temperature and finer-grained bottom sediment (canonical correlation, r=0.63, p<0.001). The reproductive peaks in February-April 1998, March-May 1999 and February-May 2002 were followed by recruitment peaks in May-July 1998, July-September 1999 and April-June 2002, respectively. Thus, the proposed period of fisheries closure (March to May) does not coincide with the main recruitment periods observed for X. kroyeri.