The Southwest Atlantic Ocean (SWAO) is a globally important region, where diverse water masses converge and mix, regulating the Earth’s climate while supporting productive fisheries and high marine biodiversity. Ecological connectivity is also substantial, with multiple species and ecosystems shared across multiple jurisdictions and international borders. However, despite historical efforts and more recent calls for regional management, the SWAO is one of the few large oceanic regions with no dedicated ocean governance body covering all shared resources. This disconnect is particularly alarming in the face of climate change, which is altering the distribution and abundance of fish stocks, shifting species ranges poleward, and intensifying uncertainty in marine resource management. A collaborative regional framework, rooted in ecosystem-based management, is urgently needed to foster sustainable management as well as bolster resilience to the impacts of climate change. As Brazil hosts a series of United Nations meetings on environmental topics, the region faces a decisive moment: either to remain reactive to external governance structures or to proactively design frameworks that reflect regional priorities, balance sovereignty concerns, and better integrate scientific evidence into decision-making. Thus, we invite decision makers, managers and scientists to take advantage of the political momentum in Latin America to advance integrated and multi-scale ocean governance, while strengthening ocean science diplomacy in the SWAO. This is a call to help navigate an uncertain future by addressing shared challenges and prioritizing ocean sustainability in the SWAO.

This study deals with the life history traits of Patagonotothen cornucola, a non-Antarctic notothenioid fish species inhabiting the Beagle Channel, focusing on key population parameters linked to the reproductive cycle, age structure and growth. P. cornucola is distributed in subtidal areas and intertidal microhabitats, exhibiting unique morphological adaptations such as a dorso-ventrally flattened body and a small size ranging from 9 to 13 cm. No sex-related dimorphism was observed, as neither the length frequency distribution nor the length–weight relationship differed between males and females. Notably, this species is an oviparous, intertidal winter spawner that provides parental care, nesting, and guarding, with a synchronous reproductive cycle. Winter spawning would ensure better development conditions during springtime to the larval stage. The study reveals a potential impact of urbanisation on P. cornucola, with evidence of feminisation linked to endocrine-disrupting chemicals due to urban runoff and sewage effluents. We highlight the need for further research on population dynamics affected by environmental stressors. The Von Bertalanffy parameters were as follows: L∞ = 131.1, k = 0.52, L0 = 7.04, and an estimated lifespan of 5 years. Otolith microincrements analyses provided a back-calculated hatching period consistent with the austral winter reproductive season. These findings are crucial for understanding the adaptive strategies of P. cornucola and informing local conservation planners in the Beagle Channel.

The northern Antarctic Peninsula (NAP), one of the fastest warming area around the Southern Ocean, hosts a large variety of endemic fish and is influenced by complex hydrography. However, the dynamics of fish diversity kept unclear and without monitoring. Monitoring of environmental DNA (eDNA) is a noninvasive, ecofriendly, and accurate approach for detecting aquatic organisms, including fish. In this study, the fish composition and diversity were detected by high-throughput sequencing of eDNA for the first time in the NAP. Overall, 32 species (1 order, 6 families, and 25 genera) of fishes were detected in the environmental water samples from 18 stations around the NAP, in which number of fish species were similar in the Drake Passage and the northern shelf of the South Shetland Islands (DP-SSIs) and the Bransfield Strait (BS). Most of the fish species were identified in previous Antarctic fish surveys using conventional methods, which supports the applicability of eDNA-based survey. Moreover, Pogonophryne albipinna was detected firstly in the NAP. Among the identified fish species, Champsocephalus gunnari and Notothenia rossii had the highest abundance (45.04% and 27.59%, respectively). There was difference in fish composition between the DP-SSIs and BS stations, although alpha diversity indices did not differ. The dissolved oxygen content and water temperature were the main drivers for the differences in fish species composition between areas. Our results indicated that eDNA could be a rapid and accurate biomonitoring approach for the entire Southern Ocean, particularly in areas with difficult logistics, in the future.

The Steelhead ecotype (Oncorhynchus mykiss) and chinook salmon (Oncorhynchus tshawytscha) have promoted a recreational fishery in the Santa Cruz river, the last large free flowing river of Patagonia. However, two dams are being built upstream in the middle course, potentially affecting the life cycle of these anadromous salmonids. The study describes the dynamics of the recreational fishing of the Santa Cruz river around Piedrabuena city and anglers perceptions, discussing its trends according to possible river connectivity scenarios. The fishery was assessed through a monthly year-round field sampling from April 2018 to April 2019, developing instantaneous angler counts, discriminating fishing methods, effort, and catch per unit effort; also, in situ interviews were used to collect information on anglers’ motivations and perceptions. In addition, information on fishing tournaments was used. Three fishing zones (FZ) were identified near Piedrabuena city: FZ-1, located downstream where anglers used baited hook and line to catch the native marine Patagonian blenny (Eleginops maclovinus); FZ-2, located in the town where baited hook and line, spinning, and fly-cast are used to catch Patagonian blenny and salmonids; FZ-3 located upstream the town, where fishing effort was mainly directed to salmonids employing spinning and fly-cast. Fishing effort showed a seasonal paern with high values from March to May and September to October, agreeing with Steelhead and Chinook salmon runs, respectively. The most relevant motivations for anglers were nonoriented catch variables. Anglers preferred the capture of salmonids over native species, considering dams to be a major threat to fishery. Although a postdamming scenario could allow the adult salmonids to migrate upstream, the current reproduction grounds of Steelhead will be flooded, and juveniles and adults of both species will be hindered in their downstream migration to sea. These aspects seem to seriously compromise the future of these unique fisheries.

Patagonian aquatic environments have been invaded since the end of the last century by different species of salmonids. Knowing the natal origin and homing/straying rate of the salmonids in colonised environments is essential to understanding the dispersal mechanisms and developing management plans. In the last two decades, Chinook salmon Oncorhynchus tshawytscha showed the greatest natural dispersal capacity in Patagonia. The main goal of this study was to evaluate the environmental strontium isotope ratio (87Sr/86Sr) as a potential natural tag to infer the natal origin and ontogenetic habitat use of salmonids in Patagonia, specifically Chinook salmon. 87Sr/86Sr ratio was determined in water samples from 26 sites distributed in 14 Atlantic and Pacific basins in low and high water seasons. Environmental 87Sr/86Sr showed greater spatial than temporal variation, revealing great potential as a tool to infer the natal origin and life history of several migratory fish species in Patagonia. Otolith core-to-edge 87Sr/86Sr profiles were also analysed in 108 Chinook salmon from six basins. A cluster analysis based on the Unweighted Pair Group method (UPGMA) and Euclidean distances without prior classification grouped the sampled rivers into five main groups with significantly different (p < 0.05) isotopic ratios, sometimes integrated basins with different slopes (Atlantic or Pacific). The cluster analysis based on the natal 87Sr/86Sr period in otolith (∼natal origin) showed clear segregation between the Atlantic and Pacific samples. A mismatch between water and otolith natal 87Sr/86Sr ratio was detected in some Atlantic basins (e.g. De las Vueltas River in Santa Cruz Basin) and Pacific (e.g. Liquiñe Basin) and, which could be explained either by straying behaviours or by large geochemical variability between tributaries, within river systems. Our results showed that 87Sr/86Sr is a useful natural tag to trace the life history of migratory fishes in Patagonia, especially for invasive species such as Chinook salmon.

The adoption of parental care behaviours is the distinctive reproductive characteristic associated with the diversification and divergence of notothenioid fishes into an array of habitats in the subzero shelf and upper slope waters around Antarctica and sub-Antarctic environments. These include a variety of pre- and post-fertilization activities, including courtship behaviour and mate choice, linked to the development of sexually dimorphic traits, nest construction and egg guarding until hatch. Using published literature and new data, this review synthesizes and evaluates, in a phylogenetic context, information related to parental care, specifically sex-specific morphological adaptations, nest location and structure, sexual differences in egg guarding and post-spawning mortality, duration of egg incubation times and larval size at hatch. The existence of parental care in phylogenetically basal notothenioids is not documented and unlikely; however, the derived lineages of the Antarctic clade (cryonotothenioids), especially bathydraconids and channichthyids, clearly exhibit a trend towards larger egg size and reduced fecundity that are considered proxies for parental care behaviours. In addition, the reproductive strategies of cryonotothenioids exhibiting parental care show latitudinal patterns at intra- and inter-specific levels. Antarctic species spawn in spring-summer and have low fecundity, large egg size at spawning and large larvae at hatching. Sub-Antarctic species spawn in autumn-winter and have moderate to high fecundity, moderate egg size and larval size at hatching, whereas non-Antarctic species spawn in winter and possess high fecundity, small egg size at spawning and small larvae at hatching.

The aim of this work was to describe the growth of Cottoperca trigloides, a notothenioid species with a non-Antarctic distribution, and to test the existence of different nursery areas and fish stocks through changes in the otolith elemental composition. Fish were collected during spring 2009 over the Patagonia continental shelf, including the Marine Protected Area Namuncura/Burdwood Bank, in the southwestern Atlantic Ocean. The age and growth analyses were performed by counting marks in sagittae, assuming an annual periodicity of their deposition, and identified 8-year classes (0+ to 7+). Given the size range of the fish, length-at-age data were fitted to the Gompertz growth model a TLt = 55.45 [exp ((exp) -0.32 (t - 1.89))1, explaining more than 95% of the growth pattern. Moreover, the chemical composition of otolith core and edge areas was analyzed by laser ablation inductively coupled plasma mass spectrometry. The canonical analysis of principal coordinates successfully allocated 72.92% of the fish for the core and 91.67% for the edge area of the otolith, in three groups corresponding to "northern Patagonia shelf," "southern Patagonia shelf," and "Marine Protected Area Namuncura/Burdwood Bank" areas, suggesting a high segregation among them over the Patagonian shelf. Thus, otolith elemental composition has proven to be an efficient approach to identify different nursery areas and stocks for the species. The present results provide new information on the growth and the population structure of C. trigloides, from a geographical area where information on this issue is still scarce, constituting an essential tool to develop conservation principles for the species.

This study presents length-weight relationships (LWR) for six species of fishes of the Suborder Notothenioidei that inhabit the sub-Antarctic waters of the Beagle Channel (Argentina). These species represent five of the nine families of this Suborder. The specimens belong to historical fish collections in the area (from 1987 to 1990) using gill and trammel nets. All species but Eleginops maclovinus had no previous LWR estimates. The coefficient of determination (r(2)) ranged from 0.91 to 0.99 and b values ranged from 2.74 to 3.2. Harpagifer bispinis was the only species with a b value lower than three. This information is useful to predict the weight from the length data and to provide insights into the ecology of sub-Antarctic nototheniod fish.

Recreational and artisanal fisheries are common activities in Latin America often interpreted as competitors due to the use of common-pool resources in coastal areas. Conflicts between the (historical) artisanal fisheries (AF) and recreational fisheries (RF) in Anegada Bay resulted in the prohibition of the former. This study addresses key fisheries characteristics to detect the degree of spatio-temporal overlap between them considering the annual dynamic of the coastal fish assemblage and proposed management alternatives. Both fisheries exerted different fishing effort coinciding with the dynamic of the fish assemblages but partial temporal and spatial overlap where apparent especially during one month. However, both fisheries focused their catches on different target species thus greatly reducing the overlap in resource use. Moreover, the low proportion of juveniles caught, limited fishing effort using selective bottom gillnets and scarce total harvest (168 tonnes/years) for AF compared with those of RF harvest (631 tonnes/years) in Anegada Bay poorly justifies the actual prohibition. However, the vulnerability index of AF landings resulted in higher values than the RF. To resolve conflicts, a co-management including AF, RF and industrial (trawl) stakeholders and non-fishing community is suggested. Because of the economic importance of fishing for local people, an efficient inter and intra-sector communications process and new fisheries guidelines are urgent for the equitable use of fisheries resources without compromising the goals of a protected area. (C) 2017 Elsevier B.V. All rights reserved.

Pampean lakes are characterised by the alternation of flood and drought periods, but little is known about its effects on fish assemblage in an extended temporal scale. This study analyses the temporal variability of the fish assemblage in Chascomús Lake, and discusses the role of temperature and precipitation as potential drivers of fish composition shifts. Data acquisition was based on experimental fishing performed from 1999 to 2013 and from historical fishing records. Two alternative fish assemblage configurations were identified by cluster analysis. Odontesthes bonariensis , Parapimelodus valenciennis and Cyphocharax voga were the dominant species, which accounted for 70–80% of the relative abundance. The species O. bonariensis showed temporal fluctuations in its representativeness, changing from dominant to almost absent, whereas C. voga and P. valenciennis changed their abundance following a similar pattern along time. When historical data were considered, Platanichthys platana appeared as the fourth most relevant species. Precipitation, critical temperatures and fish mortalities were identified as the main drivers of species abundance shifts. This study highlights the importance of long-term assessments to understand the influence of climatic factors and the need to maintain or restore natural ecological processes as the basis to support dynamic sustainable fisheries in Pampean shallow lakes.

During the research programme conducted on the OV Puerto Deseado in the summers of 2011 and 2013, 36 stations were sampled using a demersal net at depths between 53-590m in the Antarctic Peninsula and South Shetland Islands. Atotal 3378 fish specimens belonging to 36 species were recorded. Notothenidae was the best-represented family in species number, with Lepidonotothen nudifrons, L. larseni and Trematomus scotti being the most numerous species. Of the fish assemblages, 20% of the species were considered as dominant, 10% as common, 13% as occasional and 57% as rare. Six groups (and two sub-groups) were obtained by the ordination diagram based on geographical location: group 1 = Gerlache Strait, group 2 = Deception Islands, group 3 = Biscoe Island, group 4 = between Elephant and King George islands, group 5 = northern Antarctic Peninsula, and group 6 = South Shetland Islands, with sub-groups 6a shallower South Shetland Islands and 6b deeper South Shetland Islands. Sampling depth and water temperature significantly explained the spatial pattern. A latitudinal pattern of decreasing abundance from north-east to south-west was found in L. larseni and the opposite in T. scotti. The predictability of fish composition in the assemblages' areas could be a useful tool for ecosystem-based management.

This study assesses for the first time the relationship between annual cycles of different biological indices with growth patterns of a marine pejerrey Odontesthes argentinensis population near its southern-distribution boundary in North Patagonia. The reproductive period is between September and November evidenced by an increase in the gonado-somatic index with a peak in October corresponding to spawning. The reproductive cycle was also coupled with metabolic processes related to energy allocation as shown by changes in the hepato-somatic index and body condition. Total length (L(T) ) at maturity was 270 for females and 282 mm for males, whereas fecundity was estimated at mean ±s.d. = 9380 ± 1797 mature oocytes. Based on the marginal increment analysis, most of the scales showed a maximum value during summer, with a sharp decline thereafter during autumn and winter, indicating that scale rings are formed during the latter period and only once a year. Growth fitted by the von Bertalanffy model for both males and females did not show significant differences and showed a rapid growth during the first 2 years. The shorter reproductive period compared with that of the northern O. argentinensis populations inhabiting tropical and subtropical areas was interpreted as an adjustment to temperate environmental conditions. The larger maximum L(T) and L(T) at first maturity are in agreement with the counter-gradient hypothesis and could be related to the selective effects of low temperature and a shorter growing season. This latitude dependency argues strongly against the application of the same fishing regulations for different O. argentinensis populations as a whole and reinforces the need to assess basic biological features at a population scale to promote local sustainable fisheries management.

The seasonal variation of the inshore fish assemblage of Anegada Bay, North Patagonia, Argentina is described here. Three areas were seasonally sampled from 2007 to 2009 by means of a gang of bottom gill-nets. We found 21 coastal fish species, but species richness and fish number and weight changed throughout the year. The six species classified as dominant have national and regional value for artisanal and recreational fishing and were responsible for the seasonal variation in the fish assemblage. Both cluster and non-metric multidimensional scaling analyses based on fish number and fish weight indicated two major sample groups encompassing spring and summer (the warmer seasons) and autumn and winter (the colder seasons). The fish assemblage had higher species richness, dominance and abundance during the warmer seasons than during the colder seasons in the same years and at the same sites. Water temperature was the main environmental factor structuring the fish assemblage in Anegada Bay. We suggest that partial breeding migration toward the bay during warmer months could explain the seasonal pattern observed. Nevertheless, variation in temperature conditions agreed well with the pattern of seasonal changes, leading to an interaction between abiotic and biotic influences in determining the variability in this seasonal fish assemblage. We conclude that an understanding of species temporal and spatial patterns in areas of high ecological and economic value, as exemplified by Anegada Bay, are essential for the implementation of a management approach oriented toward ecosystem sustainability.

This work provides, based on data from roving creel surveys, the first quantitative analysis for a main recreational fishery of the southwestern Atlantic coast. Anglers interviewed were willing to accept minimum size limits but mostly did not approve the maximum daily catch, despite the fact that they considered that the fishery quality was decreasing. Angler profile differed among months but the avidity effect was negligible. Fishing effort was highest during January, with the greatest total catch per unit effort (CPUE) in November and the highest total catch in December. Twelve species were caught, with Cynoscion guatucupa and Micropogonias furnieri accounting for 80% of the harvest. The average lengths for both species were larger than their size at first maturity. Mean (±SD) CPUE values (1.28±0.59 fish/angler/h) and total harvest were high compared with those of other recreational fisheries in the Southern Hemisphere. Some specific fishing-management guidelines are proposed to promote good angling practices and sustainable long-term use of the resource.

El presente trabajo fue realizado en la reserva natural “Bahía San Blas”, ubicada en el sur de la Provincia de Buenos Aires, la cual posee un gran valor turístico, ecológico y productivo. Específicamente, se analizó a la pesca deportiva y a la pesca artesanal de Bahía San Blas y se relacionó su dinámica anual con la variación espacio-temporal del ensamble de peces marinos costeros. Además, se evaluaron algunas características biológicas y de interés pesquero de dos especies blanco de las pesquerías que se desarrollan en el área de estudio. Como resultado de la combinación de las metodologías de muestreo empleadas en esta tesis se registraron en la bahía 11 especies de condrictios, 26 de osteíctios y una especie de la Clase Petromizontida, con un claro predominio de peces de la Provincia biogeográfica Argentina. Para la evaluación del ensamble de peces se realizaron muestreos estacionales con redes enmalladoras de fondo en tres sitios del área sur de Bahía Anegada durante dos años consecutivos. En el análisis integral del ensamble se registraron seis especies ABUNDANTES (Mustelus schmitti, Cynoscion guatucupa, Odontesthes argentinensis, Myliobatis goodei, Micropogonias furnieri, Squatina guggenheim), ninguna CONSTANTE, tres como OCASIONALES (Brevoortia aurea, Callorhinchus callorynchus y Stromateus brasiliensis) y doce como RARAS. El análisis estacional de la riqueza específica, la CPUE y los índices del ensamble indicó en los tres sitios un claro patrón estacional de variación, en cual se destacó que los meses de primavera-verano (meses cálidos) presentan mayor diversidad de especies y mayor captura por unidad de esfuerzo en comparación con los meses de otoño-invierno (meses fríos). Este patrón de variación interanual se sostuvo en los análisis de asociación y de ordenación, en los cuales las estaciones de muestreo durante los meses cálidos se unieron como un grupo apartado de las estaciones agrupadas durante los meses fríos, y en ambos grupos la unión es independiente en cuanto a los sitios. Esta situación podría explicarse o bien con la migración y llegada de nuevas especies a la bahía durante la primavera o debido al aumento en la abundancia de especies que residen en la bahía durante todo el año. Las tres especies que más influyeron en la separación estacional son M. goodei, M. schmitti y C. guatucupa, tanto en número como en peso. Del análisis de redundancia se desprende que las variables ambientales temperatura del agua y salinidad son las que más influyen en la estructuración temporal del ensamble de peces de Bahía San Blas. La actividad deportiva en Bahía San Blas se desarrolla en la Playa de Grava y en la Playa de Arena donde se practica la pesca “variada” y también allí se desarrollan los torneos de pesca. Sobre el puente de ingreso a la bahía se practica una pesca dirigida especialmente a pejerrey y a lenguado. A su vez, la pesca embarcada se desarrolla alquilando embarcaciones propiedad de los guías locales y está dirigida mayormente hacia la pesca variada. La actividad deportiva mostró un carácter netamente estacional, concentrándose en los meses primavera y verano. La metodología “roving creel census” que se aplicó para caracterizar la pesca deportiva costera de Bahía San Blas incluyó un muestreo piloto para conocer los estratos y posteriormente un esfuerzo de muestreo de 63 días entre noviembre de 2008 y abril de 2009 (temporada I) cuando se realizaron 507 entrevistas y de 108 días entre junio de 2009 y abril de 2010 (temporada II) (excepto Mayo y Agosto de 2009) cuando se consiguieron 856 entrevistas. Estas fueron ideadas para relevar conjuntamente características socio-económicas y pesqueras. Entre las primeras se destacó que los pescadores de playa fueron mayormente adultos masculinos de entre 40 y 60 años de edad que vinieron desde distintas provincias del país a lo que consideraron el mejor pesquero recreativo de la costa Argentina. La corvina rubia fue la especie blanco preferida seguida de la categoría “sin preferencias”. Entre 30 y 40 cm se halló la medida escogida por la mayoría como talla mínima para retener la captura aunque el 21% advirtió que cada especie debería tener una talla mínima particular. Además, la mayoría desearía capturar todos los peces posibles durante un día de pesca. Se halló un patrón estacional en la valoración diaria de la jornada de pesca, siendo los meses de octubre, noviembre y diciembre los mejores calificados y los meses de verano los peores. A pesar de que la CPUE fue mayor a fines de primavera, el esfuerzo de pesca en ambas temporadas mostró una tendencia mensual creciente hasta alcanzar en enero el máximo valor y luego descendió para hacerse mínimo durante los meses de invierno y otoño. Al igual que otras pesquerías recreacionales, el esfuerzo en fines de semana fue mayor que en días de semana, a excepción de los meses vacacionales de verano. Este hecho se explicaría por la mayor disponibilidad horaria y por lo tanto la programación de la salida de pesca incluiría otras variables además del rendimiento pesquero (perfil “pescador recreacional”). En cambio, durante noviembre y diciembre predominaría el perfil de “pescador extractivo” cuya principal motivación de pesca sería la captura de peces y fue caracterizado en este trabajo por su mayor valor de equipo de pesca y por su participación en más salidas de pesca embarcada. Entre las capturas, la pescadilla de red y la corvina rubia constituyeron las principales especies blanco, ya que en conjunto aportaron más del 60% de la captura mensual en peso. Las capturas en número y peso fueron máximas en el mes de diciembre en ambas temporadas. Se estimó una captura de 193 toneladas durante la primera temporada y de 235 toneladas en la segunda. Los dos sciaenidos fueron capturados por encima de su L50, mientras que las tallas de captura de gatuzo se encuentran por debajo de su L50 y por ello se recomienda su captura con devolución. La pesca en el puente recibió un esfuerzo de pesca muy inferior con respecto a las playas. La CPUE fue mayor durante la primavera y las capturas fueron mayormente de O. argentinensis, las cuales superaron el 85% en todos los meses.La pesca embarcada se desarrolla en San Blas entre octubre y abril de cada año. Es en noviembre y diciembre cuando se realizan proporcionalmente más salidas de pesca en relación al número de turistas que ingresaron a la bahía y en enero cuando se produjo el mayor número neto de salidas de pesca. La CPUE estimada varió entre 6,8 y 8,1 peces por hora por pescador y las capturas se concentraron en pescadillas, corvinas, gatuzos y rayas. La pesca artesanal se desarrolló según un plan de operaciones consensuado con la autoridad de aplicación entre el año 2002 y el 2007 y a partir de ese año fue prohibida. La temporada de pesca era acotada entre octubre y mitad de diciembre de cada año y se realizaba con un máximo de siete redes agalleras de fondo de 105 mm de abertura por embarcación. Éstas, que sumaban no más de 16, eran tripuladas por residentes en el área para los que la pesca artesanal representaba el pilar fundamental de la economía familiar. El análisis de los desembarques permitió definir a esta pesquería como monoespecífica y dirigida hacia el gatuzo y por lo tanto no interfiere con las dos principales especies blanco de la pesca deportiva. Las capturas artesanales de gatuzo eran mayormente adultos, alcanzaban un total de 164 toneladas promedio por temporada, lo que equivale apenas al 2% de la captura de esta especie a nivel nacional. Considerando estos resultados la prohibición de la actividad se considera poco justificada. El análisis de las capturas experimentales de esta especie permitió identificar un patrón estacional en el que los gatuzos de mayores tallas se registraron en los meses cálidos y los meses fríos se caracterizaron por gatuzos de tallas menores. En este sentido, el análisis de asociación de sitios en función de las tallas de gatuzos demostró que las estaciones de primavera y verano conforman un grupo separado de los sitios de muestreo durante otoño e invierno. También fue durante primavera y verano cuando se hallaron hembras con crías. Las hembras alcanzan mayores tallas que los machos y sus L50 se estimaron en 56,3 y 54,3 cm de longitud total respectivamente. En cuanto a la CPUE, los mayores valores se hallaron en primavera, seguido del verano, otoño y por último invierno. Con base en estos resultados, se propone un uso estacional de la bahía como parte del ciclo de vida de la población de gatuzo que incluye la llegada de adultos a la bahía en primavera para el alumbramiento, posterior apareamiento y nueva migración en verano-otoño, y la permanencia de los juveniles en el área que funcionaría como nursery. El pejerrey escardón O. argentinensis posee interés pesquero deportivo y fue solicitada para su pesca artesanal en el área de estudio. La aplicación de técnicas de morfometría geométrica y de genética no diferenciaron los dos morfotipos de O. argentinensis que sí reconocen a simple vista algunos pescadores artesanales de la zona .Mediante muestreos mensuales realizados durante un ciclo anual pudo determinarse que el paño 32 es el más eficiente en cuanto al número de capturas de tamaño comercial. Sin embargo, este paño retiene incidentalmente un 20% en peso de gatuzo juvenil.Por otro lado, el análisis del valor medio mensual del IGS de O. argentinensis indicó un período reproductivo que abarca desde septiembre a noviembre con un pico en octubre cuando la temperatura se halló por debajo de los 20°C. Esta especie se comporta en el área de estudio a modo de un desovador total de unos 9380 ovocitos promedio por hembra por año. La estrategia reproductiva se modificó respecto de las poblaciones de latitudes más altas y se habría ajustado a las condiciones templadas de la bahía. Se halló que las hembras fueron más numerosas y alcanzan mayores longitudes que los machos (44 vs 40 cm) y sus L50 se calcularon en 27 y 28 cm respectivamente. Estas tallas son superiores a las registradas en el sur de Brasil y guardarían relación con las condiciones ambientales. El estudio de edad y crecimiento empleando escamas indicó que el crecimiento no difiere entre sexos y que el rango de edad de la población varía entre 1 y 7 años. Los parámetros de la curva de von Bertalanffy fueron: L∞ = 404 mm, k = 0,48 y to = 0,55. Estos valores están dentro del rango esperado para el género. Se halló una mortalidad media de 0,65 y una longitud óptima de 28 cm. Se destaca la escasez de ejemplares menores a 27 cm en las áreas muestreadas. El paño 32 mm utilizado por la pesca artesanal impacta en pejerreyes de 4 o más años que ya superaron la talla crítica y la de madurez y por lo tanto su pesca se practicaba con criterios precautorios. En caso de habilitar nuevamente esta pesca, es necesario restringir los permisos de pesca a los residentes locales, limitar los sitios habilitados para la pesca y las metodologías de captura para minimizar la pesca incidental de gatuzo juvenil. Finalmente, se concluyó que existe una relación directa entre la dinámica anual del ensamble de peces de Bahía San Blas y el esfuerzo y la CPUE de la pesca recreativa, y también entre el ciclo de vida del gatuzo y temporada de pesca artesanal. Se proponen medidas de manejo que propicien una administración sustentable del recurso pesquero.

The smooth-hound Mustelus schmitti is a commercially important and common target shark inhabiting the southwestern Atlantic coastal system and is usually found in shallow waters. Using experimental and artisanal fishing records, we assessed seasonal biological and demographic characteristics related to fishing of the smooth-hound and its potential impact on this species. We found that after birth, juveniles remain in Anegada Bay until sexual maturity. The young adults mate in spring and then leave the bay in summer. The older adults come back to the bay in early spring to give birth, and mate and finally return to the open sea in late spring. This pattern suggests that the bay acts as a seasonal nursery and reproductive area. This species represents 95% of the fishery captures in this bay, although the fishery is highly seasonal. The average harvest during the years 2003–2008 was 164tons, which represented only 2% of the total Argentinean smooth-hound landings. Fishing effort in the bay can be considered moderate due to the narrow time window and the use of selective gear that prevents the capture of juveniles. Future research should be directed at developing management plans at a broader regional scale to allow the recovery of M. schmitti stocks under heavy fishing pressure in other fishing areas.

We provide the first list of marine fish from Anegada Bay, a coastal protected area in Buenos Aires Province. Fish records were obtained from gillnets and recreational fishery captures. Thirty seven species belonging to 29 families and 18 orders were identified. The most numerous order was Perciformes with eight families and 10 species. Odontesthes argentinensis, Micropogonias furnieri, Cynoscion guatucupa and Mustelus schmitti were verified in all sampling sites and the last two were the most represented either in the experimental fishing and recreational captures. Presence of Lagocephalus laevigatus extended the so far known range distribution of this fish species, representing the southernmost records in Argentinean coastal waters. The fish fauna composition from Anegada Bay could be considered as from a transitional zone.