Life history traits influence in gonad composition of two sympatric species of flatfish

AbstractParalichthys orbignyanus and Paralichthys patagonicus are flatfish with different life history traits, having in common the condition of breeding in seawater. Paralichthys patagonicus remain their whole life in open seawater and Paralichthys orbignyanus are sometimes found in brackish water bodies. As marine and estuarine food webs have different fatty acid (FA) compositions, the aim of this study was to characterize the gonadal maturation of P. orbignyanus and P. patagonicus females through the analysis of lipid content and FA profile in order to understand to what extent life history traits are reflected in the ovarian composition. During gonadal maturation lipid content increased and FA profiles changed in both species, but the lipid increase was greater in P. orbignyanus. The N-3FA and n-3HUFA proportions increased in both species but were higher in P. orbignyanus. The differences between the lifestyles of these species were reflected in the ovarian FA profile mainly as a result of differences in their FA metabolism, causing a greater accumulation of n-3FA and n-3HUFA in P. orbignyanus than in P. patagonicus. The higher lipid accumulation in P. orbignyanus’ ovaries could indicate that this species, feeding in brackish water bodies, has the possibility of storing more energy than P. patagonicus

Fishermen's local ecological knowledge on Southeastern Brazilian coastal fishes: contributions to research, conservation, and management

We analyzed fishermen's local ecological knowledge (LEK) about the feeding habits, trophic interactions, habitats, fishing grounds, migration, and reproduction of nine coastal fishes in Búzios Island, southeastern Brazilian coast. We interviewed 39 fishermen using standardized questionnaires. Fishermen's LEK on habitat use and trophic interactions for the studied fishes agreed with the scientific literature, allowing the organization of reef and pelagic food webs. The interviewed fishermen mentioned that submerged rock formations would be important habitats for some large commercial fishes, such as Seriola spp., Caranx latus and Epinephelus marginatus. In some instances there was no scientific data to be compared with fishermen's LEK, and thus this kind of knowledge would be the only available source of information, such as for reproduction and migration of most of the studied fishes. We suggest herein ways to apply fishermen's LEK to develop and improve fisheries management measures, such as zoning of marine space, marine protected areas, and closed fishing seasons. Fishermen's LEK may be an important and feasible support to fisheries management and co-management

Wind effect as forcing factor controlling distribution and diversity of copepods in a shallow temperate estuary (Solis Grande, Uruguay)

Spatial and temporal variations of planktonic copepods were investigated in relation to environmental conditions in the Solís Grande estuary (34°22´S, 55°33´W), Uruguay. Over a period of fifteen days, samples were taken daily at three stations along the main axis of the estuary, and the species composition and abundance were determined. The Solís Grande is a shallow estuary (2.0 m) with no vertical discontinuities. Comparisons of surface versus bottom hydrographic values indicated no vertical stratification of temperature and salinity during the studied period. The species-environmental relationships explain 63.6% of the system´s variability considering the two first axes from Redundance Analysis (RA). Copepods showed strong differences in distribution and abundance between stations and successive days. In the region the winds quickly rotate from sectors S-SE (frontal period) to E-NE (post-frontal period). Changes in abundance were significantly related to the inflow and outflow of water produced by the rotation of winds. At smaller space and time scales, the differences highlighted by the RA were the result of wind-forced hydrodynamics after the frontal period. In this situation hydrographic features were dominant (factor one of RA) and wind effects were of secondary importance (factor two of RA). Six species were identified and the estuary was clearly dominated by Acartia tonsa. The results showed two negatively correlated groups: one was integrated by Oithona nana, O. simplex, Paracalanus parvus and P. crassirostris while the second group was integrated by A. tonsa and Euterpina acutifrons. Environmental variability may be responsible for the low diversity.No disponibl

Structure by size, sex and maturity stage of the withe croaker (Micropogonias furnieri, Desmarest, 1823; Teleostei: Sciaenidae) in the bycatch of the artisanal fishery at Rocha Lagoon, Uruguay

The structure of the population of white croaker (Micropogonias furnieri), a bycatch species of the multi-specific artisanal fishery at the coastal lagoon of Rocha, was analyzed. This species is Uruguay's second fishery resource and it has been declared fully exploited. Few data are available on the artisanal fishery and the biology of this fish, which inhabits the Uruguayan coastal lagoons. The white croakers were obtained from the bycatch of five fisheries that target diverse species in different parts of the lagoon. The five net types studied (mesh sizes 1, 2, 4, 10 and 20 cm) caught different fractions of the structure per size, sex and maturity stage. Both the median and first quartile of the size composition retained by each net size were bigger than the size at first maturity. This work shows the effect of different kinds of artisanal fishery on the structure of the white croaker population and provides basic information for the conservation and management of one of the fishery resources whose habitat forms part of the national park within the MAB/UNESCO Bañados del Este Biosphere Reserve