Isotope-based inferences of skipjack tuna feeding ecology and movement in the southwestern Atlantic Ocean.

Skipjack tuna (Katsuwonus pelamis) sustain a large-scale fishery in the southwest Atlantic Ocean (SWA), but information about its foraging ecology in this region is still limited. Here we use carbon (δ13C) and nitrogen (δ15N) stable isotope analysis of muscle from individuals collected in 2017-2018 (n = 383) to quantify diet composition and characterize movement patterns. We found a relatively small degree of variation in δ13C (range: -18.9 to -16.5‰) in comparison to δ15N values (6.7-14.7‰). At higher latitudes in the southern area (30-34°S), individuals had higher mean (±SD) δ15N values (12.2 ± 1.3‰) in comparison to those collected in the northern area (9.7 ± 1.5‰) between 20-26°S. At the northern area, isotope mixing models with informative priors showed that lanternfish (median: 50%) and krill (31%) were the primary foods. In the southern area, lanternfish (53%), krill (23%) and small pelagic fish (23%) were the primary food sources. Spatial shifts in diet composition were related to warming events that likely resulted in low abundance of sardines in the northern area. The latitudinal pattern in skipjack and krill δ15N values mirrored that of regional zooplankton isoscapes, suggesting residency at the timescale of isotopic turnover for muscle (~2-4 months), and that geographical variation in the baseline isotopic composition can be exploited to characterize seasonal movements of skipjack and other top marine consumers in this region.

Ingestion of plastic debris by commercially important marine fish in southeast-south Brazil.

Rising concentrations of plastics in the oceans are leading to increasing negative interactions with marine biota, including ingestion by endangered and/or economically important seafood species such as fish. In this paper, we visually evaluated plastic debris ingestion by 965 specimens of eight commercially exploited fish species from different marine habitats off the southeast-south coast of Brazil. All species ingested plastics, with pelagic animals having higher amounts, frequency of occurrence, diversity and sizes of ingested items than demersal-pelagic and demersal animals. Highest frequency of occurrence (FO%) of plastic ingestion (25.8%) was observed for the pelagic skipjack tuna Katsuwonus pelamis (Scombridae), and lowest (5%) for the demersal bluewing searobin Prionotus punctatus (Triglidae). Microplastics predominated in all species, and fibers/lines and fragments were the main items found, possibly derived from fishing materials. The most abundant plastic colors were transparent, black and blue, and the most common polymers were polyamide and polyurethane. With the available data, no relationship between the size of the individuals and amount of ingested plastics was observed. Considering the negative impacts of plastic ingestion on marine fish, and potentially on human health due to their consumption, understanding ingestion patterns is critical for better evaluating their origin and possible causes, and consequently for helping define prevention strategies for this problem.

Domoic acid in the tropical South Atlantic Ocean - An environment case study.

Domoic acid (DA) or Amnesic Shellfish Poisoning (ASP) produced by the genus Pseudo-nitzschia diatom was investigated in two seasonal periods in fishing areas of Katsuwonus pelamis in the South Atlantic Ocean. Higher DA concentrations were found in spring compared to winter. Pseudo-nitzschia spp. more quantified in winter than in spring, while P. pungens, a species among the most reported for an AD toxic potential, was only found in spring.

Potencial de inserção de empanados de pescado na merenda escolar mediante determinantes individuais / Potential inclusion of breaded fish products in school meal by individual determinants

O pescado é uma fonte importante de proteína animal e, por ser um produto perecível, uma solução estratégica para superar a curta vida útil representada pelo pescado fresco seria a elaboração de empanados a base de pescado, produto com qualidade, conveniente e mais adequado à demanda do consumidor moderno. No Brasil, programas governamentais de merenda escolar vêm trazendo apoio a pesquisas para o desenvolvimento de novos produtos a base de pescado e que sejam de fácil aceitação para crianças em idade escolar. Nesse sentido, o objetivo do trabalho foi detectar os determinantes individuais do consumo de pescado com adolescentes em idade de 12 a 17 anos, visando à inserção de empanados de pescado na merenda escolar. Os dados foram obtidos a partir de 92 alunos de uma escola localizada no município de Rio Grande - RS, mediante aplicação de um questionário elaborado com perguntas a respeito de suas atitudes e preferências, consciência saudável, conveniência e fatores sociodemográficos. A análise dos resultados foi realizada com base na técnica multivariada da análise de discriminante, em que se buscou discriminar grupos formados em função da frequência de consumo de pescado (nunca consome pescado; uma vez ao mês; duas vezes ao mês; uma vez na semana; e mais de uma vez na semana). Os resultados permitiram concluir as variáveis melhores discriminantes da frequência de consumo de pescado definidas pelo teste de diferença de médias de Lambda Wilks' Parcial, que foram "gosta de pescado" (0,55) e "grau de escolaridade dos pais" (0,88). Os dois primeiros modelos discriminantes obtidos explicaram juntos 75% da variância para a frequência de consumo de pescado. A maioria dos indivíduos apresentou a ideia de que empanado não é saudável, mas que possuem o hábito de consumi-lo pelo menos de uma a duas vezes ao mês. O grupo que nunca consome pescado disse não gostar de pescado e 50% das observações registradas estão entre consumir empanado de uma vez ao mês a mais de uma vez na semana. Estes resultados indicaram um potencial de consumo de empanado de pescado por adolescentes, associado à necessidade de educação alimentar.

Fish products are an important source of animal protein and being perishable product, a strategic solution to overcome the short life represented by the fresh fish is the development of the breaded fish, a product of quality, convenient and better suited to the modern consumer demand. In Brazil, government programs for school meals have brought support for research to develop new products based on fish that are easily accepted by school children. In this sense, the objective was to detect individual determinants of fish consumption in adolescents aged 12-17 years, aiming the inclusion of breaded fish in school meal. Data was obtained from 92 students in a school located in Rio Grande - RS, by applying a questionnaire with questions about their attitudes and preferences, health consciousness, convenience and socio-demographic factors. The analysis was performed based on the technique of multivariate discriminant analysis, where one seeks to discriminate groups formed according to the frequency of fish consumption (never consumed fish; once a month, twice a month, once a week and more than once a week). The results led to the best discriminating variables in the frequency of fish consumption defined by the Partial Lambda Wilks' mean difference test which were "likes fish" (0.55) and "educational level of parents" (0.88). The first two discriminant models obtained explained 75% of the variance for the frequency of fish consumption. Most individuals presented the idea that breaded products are not healthy, but they had the habit of consuming them at least once or twice a month. The group that never consumed fish said to dislike fish and 50% of the observations are recorded between consuming breaded once a month to more than once a week. These results indicate a potential for breaded fish consumption by adolescents, associated with the need for nutrition education.