Evaluation of the Blue Crab Callinectes sapidus Rathbun, 1896 Bycatch in Artisanal Fisheries in Southern Brazil

ABSTRACT We evaluated the incidental catch of the blue crab in artisanal fisheries through the analysis of sex ratio, catch per unit effort, net positioning, and size in which the capture probability was 50% (P50). The specimens were collected from 2011 to 2013 in the estuary of Patos Lagoon, southern Brazil. The analysis showed a higher occurrence of males. Variations in the catch per unit effort showed greatest abundance values close to the mouth of the estuary. Catch per unit effort was similar when comparing fishing seasons and net positions. P50 indicated a low selectivity of the nets since it varied between studied areas but stayed below the size at first maturity. Catches indicated a greater effort on males, since females migrated to spawn in the ocean area adjacent to the estuary during the fishing period studied. The spatial variation of the catch per unit effort showed heterogeneity in fishing catches. Thus, optimal management of the resource should consider the particularities of each area.

Range extension of the mud crab Eurypanopeus depressus (Smith, 1869) (Decapoda, Panopeidae): A new record for the coastal south of Brazil / Expansão da distribuição do caranguejo Eurypanopeus depressus (Smith, 1869) (Decapoda, Panopeidae). Um novo registro para a costa do sul do Brasil

The discovery of Eurypanopeus depressus (Decapoda: Panopeidae; Smith, 1869) on the coast of Rio Grande do Sul, Brazil suggests that the species was recently introduced, possibly due to different sources of introduction, such as the ballast water of ships. E. depressus were collected using otter-trawl net in the Patos Lagoon Estuary. Discussion focuses on the fact that the primary South American distribution derives from Uruguayan shores, and later expanded to nearby places (Brazil and Argentina). This work extends the Southern Hemisphere distribution for the species, as it was previously reported only from Argentina to Uruguay.

O registro de Eurypanopeus depressus (Smith, 1869) na costa do Rio Grande do Sul, Brasil (Decapoda:Xanthidae) levanta a hipótese de que a espécie pode ser invasora, devido a diferentes fontes de introdução como água de lastro. E. depressus foi coletada com rede de portas no estuário da Lagoa dos Patos. A discussão foca no fato de que a distribuição primária da espécie na América do Sul pode ter sido na costa uruguaia, tendo esta posteriormente se irradiado para locais próximos (Brasil e Argentina). Este trabalho estende a distribuição da espécie no hemisfério sul, já que previamente era citada somente para a Argentina e Uruguai.

Compostos nitrogenados sobre o consumo alimentar de camarão-rosa Farfantepenaeus brasiliensis / Nitrogen compounds on food consumption of pink-shrimp Farfantepenaeus brasiliensis

Os experimentos foram realizados para investigar os efeitos da amônia, nitrito e nitrato no consumo alimentar de juvenis de Farfantepenaeus brasiliensis. Os camarões com peso médio de 4g foram aclimatados durante 28 dias em diferentes concentrações crônicas de amônia, nitrito e nitrato. Após o período de exposição de 28 dias, 20 camarões por tratamento foram individualizados em unidades experimentais de 3 L, a fim de ser analisado o consumo de ração em função da quantidade de alimento oferecido e as sobras durante um período de 24 horas. O consumo alimentar apresentou alterações significativas (P<0,05) para os camarões expostos às concentrações de nitrito e nitrato testadas, enquanto para o tratamento com amônia, os camarões não apresentaram alterações no consumo alimentar (P>0,05). Foi verificado que o nitrito e o nitrato afetam o consumo alimentar de F. brasiliensis. Contudo, a possibilidade de que isso ocorra durante longos períodos, afetando negativamente o cultivo de espécies em cativeiro, reforçam a necessidade do manejo da qualidade de água.

The experiments were carried out to investigate the effects of ammonia, nitrite and nitrate on food consumption of juvenile F. brasiliensis. The juvenile shrimp were acclimated for 28 days with different cronic concentrations of ammonia, nitrite and nitrate. After the acclimation period, 20 shrimps per treatment were individualized in 3 L experimental units in order to analyze their feed intake through the amount of feed offered and leftover for a period of 24 hours. The food consumption presented significant alteration (P<0.05) for the nitrite and nitrate concentrations tested, meanwhile on ammonia treatment, shrimp presented no alteration on food intake (P>0.05). According to the results obtained, nitrite and nitrate affected F. brasiliensis food consumption. However, the possibility of this to happen over long periods, can damage the species in captivity, reinforced the necessity of regular water quality management.

Natural diet of Neohelice granulata (Dana, 1851) (Crustacea, Varunidae) in two salt marshes of the estuarine region of the Lagoa dos Patos lagoon

Natural diet of Neohelice granulata in two salt marshes of Lagoa dos Patos, RS were studied. Sampling was performed seasonally and crabs were captured by hand by three persons during one hour, fixed in formaldehyde (4 percent) during 24 h, transferred to alcohol (70 percent). Each foregut was weighed and repletion level was determined. Differences between sexes in the frequencies of occurrence of items were tested by χ2test. A total of 452 guts were analyzed. Quali-quantitative analyses were calculated following the method of relative frequency occurrence and relative frequency of the points. At both sites, for both sexes and in all seasons, the main food items were sediment, Spartina sp. and plant detritus. The highest values of mean repletion index were estimated for the spring and summer. Analysing both salt marshes, in different seasons significant shifts in the natural diet of Neohelice granulata was not observed throughout the period of study.

Mortality of Kalliapseudes schubartii in unvegetated soft bottoms of the estuarine region of the Lagoa dos Patos

Kalliapseudes schubartii (Crustacea: Tanaidacea) é um invertebrado tubícola que habita fundos moles de regiões estuarinas e que distribui-se ao longo da costa sudeste e sul do Brasil e na costa uruguaia. Este tanaidaceo é comedor de depósitos e filtrador, e é presa de vários consumidores secundários. Taxas de mortalidade sazonal foram examinadas através de amostras feitas durante um ano num local da região estuarina da Lagoa dos Patos. Os resultados não demonstraram diferenças significativas entre as taxas de mortalidade nas diferentes estações do ano, o que sugere que populações de K. schubartii são fortemente predadas ao longo de todo o ano e que a premissa de maior mortalidade no verão/outono pode não ser correta em fundos de águas rasas não vegetados.