Digestive Proteases From Fish Processing Wastes: Their Partial Characterization and Comparison

Fish processing generates a lot of wastes which are discarded resulting in environmental problems. However, this material represents a significant source of high-value bioproducts with potential biotechnological applications. The objective of this study was to characterize and to compare specific activities of acid and alkaline proteases recovered from the viscera of Merluccius hubbsi (Mh), Percophis brasiliensis (Pb), Urophyis brasiliensis (Ub), and Cynoscion guatucupa (Cg) under different pH and temperature conditions. Stomach proteinases from four species had a higher activity at pH 2, with stability in the range of pH 2-4. Optimum pH from intestinal enzymes of Cg was 11.5, while for the crude extract of Mh, Pb, and Ub catalytic activity was registered over a wide pH range range from 7 to 11.5. Stomach proteinases from four studied species had a higher activity at 30 °C and 50 °C, with stability at 10 °C and 30 °C. Optimum temperature from intestinal enzymes of the four tested species was 50 °C with high stability at 10 °C and 30 °C. Alkaline proteinase from all species and acid proteinases from Cg was inactivated at 70ºC, while stomach enzymes of Mh, Pb, and Ub had a residual activity lower than 5% at 80 °C after 5, 10 y 20 minutes of pre-incubation, respectively. Digestive proteinases recovered in this study could be used as biocatalysts in industrial processes, reducing costs, adding value to the fishery waste, and contributing to the reduction of environmental pollution.

First data on the age and growth of Brazilian flathead Percophis brasiliensis (Pisces: Perciformes) in San Matías Gulf, northern Patagonia (Argentina)

Brazilian flathead Percophis brasiliensis is a commercially important perciform fish caught as bycatch by trawlers throughout its latitudinal distribution range (from 23° S in Brazil to 47° S in Argentina). It is associated with the catches of Argentine hake Merluccius hubbsi and Patagonian red shrimp Pleocticus muelleri in San Matías Gulf (SMG). The main objective of this study was to describe the first data on the growth of this species in SMG and to compare the results with available information for other areas of the Argentine Continental Shelf (ACS). The study was carried out using 294 specimens (196 females, 97 males and one of indeterminate sex) collected over four non-consecutive years from commercial/recreational fishing and during research cruises. The age of individuals was determined by reading and counting opaque-hyaline rings on the sagittae otoliths. The maximum ages observed were 14 years for females and 12 years for males. Growth parameters were estimated using the von Bertalanffy mode. Significant differences in L∞ parameter between sexes were found (L∞ males = 54.58 cm; L∞ females = 78.31 cm, p < 0.05). Growth parameters were different from those determined in previous studies for the ACS.

QUALIDADE DA CARNE MECANICAMENTE SEPARADA (CMS) E DO SURIMI OBTIDOS DE PEIXES DE BAIXO VALOR COMERCIAL

Este estudo teve como objetivo analisar a qualidade e as diferenças entre a carne mecanicamente separada (CMS) e surimi obtidos a partir de pargo (Pagrus pagrus) e o tira-vira (Percophis brasiliensis) capturados na categoria “mistura” da modalidade da pesca de arrasto de Niterói, RJ. Para elaboração do surimi, as CMS de pargo e tira-vira foram submetidas à lavagem. A caracterização química dos produtos foi determinada pelas análises da composição química (umidade, proteína,lipídeos e cinzas). Para as análises microbiológicas foram realizadas contagens de Estafilococos coagulase positiva, coliformes a 35 °C, coliformes termotolerantes e pesquisa de Salmonella sp. Os surimis de pargo e tira-vira apresentaram menores teores proteico (7,84% e 7,34%) e lipídico (0,73% e 0,74%) e maior umidade (91,71% e 90,15%), respectivamente, em comparação à CMS (P<0,05). A análise microbiológica demonstrou que os produtos estavam dentro do padrão sanitário exigido pela legislação. Com base nos resultados obtidos, conclui-se que os peixes de baixo valor agregado da categoria “mistura” resultaram em produtos (CMS e surimi) viáveis para o uso na tecnologia do pescado. O produto CMS apresentou-se mais rico nutricionalmente do que o surimi, porém com maior carga bacteriana.

Parasites of the Brazilian flathead Percophis brasiliensis reflect West Atlantic biogeographic regions

SUMMARYWith the aim of evaluating the utility of marine parasites as indicators of zoogeographical regions in the South West Atlantic, we analyzed data on assemblages of long-lived larval parasites of 488 specimens of Percophis brasiliensis distributed in 11 samples from nine localities covering the entire distribution of the species in the Argentine biogeographical Province. Near half a million long-lived parasite individuals belonging to 17 species present in the whole sample displayed clear latitudinal patterns. Data for parasite assemblages at infracommunity and component community levels were analysed in relation to the geographical distance. Significant similarity decay of parasite assemblages over distance was observed, with those based on abundances and mean abundances showing departures from predicted values of regressions. These departures were represented by higher dissimilarities between samples coming from different zoogeographical regions than between those caught within the same region, independently of the distance separating them. Consequently, zoogeographical regions were identified in a distance-decay context. Multivariate analyses corroborated a close fit of similarity between assemblages to existing zoogeographical classifications. Regressions representing distance decay of similarity, and the identification of their outliers, can therefore shed light on the existence of discontinuities or uniformities in the geographic distribution of parasite assemblages and, in turn, in the zoogeography of their fish hosts.

Use of otolith strontium:calcium and zinc:calcium ratios as an indicator of the habitat of Percophis brasiliensis Quoy & Gaimard, 1825 in the southwestern Atlantic Ocean

We evaluate the simultaneous use of Sr: Ca and Zn: Ca ratios of the sagitta otolith as a potential indicator of the habitat of Percophis brasiliensis along a latitudinal gradient in the southwestern Atlantic Ocean (34-42ºS and 51-67ºW), in order to reliably identify fish stocks. Fish were collected in three sampling sites: Argentine-Uruguayan Common Fishing Zone (AUCFZ), El Rincón (ER) and San Matías Gulf (SMG). The otolith Sr:Ca and Zn:Ca ratios were determined by ICP-OES and EDTA volumetric method. The otolith Sr:Ca ratio was similar in the three sampling sites, while the Zn:Ca ratio was significantly higher in AUCFZ than in ER and SMG for all age groups. The discriminant analysis showed an association between the otolith Sr:Ca and Zn:Ca ratios from ER and SMG. Present results suggest the potential occurrence of two fish stocks of P. brasiliensis in the study area.