Larval Fish Community in the Northwestern Iberian Upwelling System during the Summer Period

The Galician shelf (northwestern Iberian Peninsula) is a highly dynamic area with an important multi-species fisheries industry that exploits resources from several habitats, characterized by being not only highly diverse, rich, and productive but also seasonally and interannually variable. Early life stages of different species are distributed throughout the year, with fluctuating abundances and community composition. Likewise, the influence of environmental factors and processes on larval production and survival remains unknown. Sampling was carried out in July 2012, and all the larvae obtained were identified to establish the specific composition of the community in a summer upwelling scenario. The results show no zonation in the species distribution, a consequence of the mixing effects of the upwelling and eddies, with high diversity but low abundance, which render in a slight predominance of a few species. Due to the dependence of planktonic populations on upwelling events, which was not highly pronounced in 2012, we cannot conclude that this was a typical conformation of the Galician summer larval fish community, but it is a first approach to comprehend the community composition.

Effects of Microalgae Chlorella vulgaris Density on the Larval Performances of Fresh Water Prawn Macrobrachium rosenbergii (De Man, 1879)

Background: Microalgae have several potential applications in early stages especially in the hatchery phase of several fish, mollusc and crustacean species. The present study aimed to evaluate the effects of microalgae Chlorella vulgaris at different concentrations on larval performances of Macrobrachium rosenbergii. Methods: Freshly hatched larvae were reared until the metamorphosis of first post larval (PL) stage in plastic aquaria (5 liter, 12ppt and 12L:12D) with a density of 10 larvae/liter under five randomly arranged treatment groups in 3 replicates such as, 0×105 (T1, control) and four different concentrations of C. vulgaris 5×105 (T2), 10×105 (T3), 15×105 (T4) and 20×105 (T5) cells/ml. Larvae were fed Artemia (6 nauplii/ml) six times daily. Result: The results revealed that the addition of microalgae in rearing system significantly enhanced (P less than 0.05) the larval survival and developments than without microalgae. The highest larval survival and faster appearance of PL (in days) was observed in T3 group (60.83%, 24.67 days) followed by T4 (56.91%, 28.33 days) T2 (48.39%, 31.33 days) T5 (40.93%, 32.33 days) and T1 (30.65%, 39 days), respectively. Larvae reared at moderate concentrations of microalgae (T3 and T4) resulted in high dry weight that of extreme low (T2) or high (T5) concentrations of microalgae. This study identified the best concentration of Chlorella vulgaris for the rearing of M. rosenbergii larval and could be applicable for the mass larval production of this species commercially.

Evidence that spillover from Marine Protected Areas benefits the spiny lobster (Panulirus interruptus) fishery in southern California

Marine Protected Areas (MPAs) are designed to enhance biodiversity and ecosystem services. Some MPAs are also established to benefit fisheries through increased egg and larval production, or the spillover of mobile juveniles and adults. Whether spillover influences fishery landings depend on the population status and movement patterns of target species both inside and outside of MPAs, as well as the status of the fishery and behavior of the fleet. We tested whether an increase in the lobster population inside two newly established MPAs influenced local catch, fishing effort, and catch-per-unit-effort (CPUE) within the sustainable California spiny lobster fishery. We found greater build-up of lobsters within MPAs relative to unprotected areas, and greater increases in fishing effort and total lobster catch, but not CPUE, in fishing zones containing MPAs vs. those without MPAs. Our results show that a 35% reduction in fishing area resulting from MPA designation was compensated for by a 225% increase in total catch after 6-years, thus indicating at a local scale that the trade-off of fishing ground for no-fishing zones benefitted the fishery.

Spatial ecology and growth in early life stages of bay anchovy Anchoa mitchilli in Chesapeake Bay (USA)

The bay anchovy Anchoa mitchilli is the most abundant fish in Chesapeake Bay (USA) and is a vital link between plankton and piscivores within the trophic structure of this large estuarine ecosystem. Baywide distributions and abundances of bay anchovy eggs and larvae, and larval growth, were analyzed in a 5 yr program to evaluate temporal and spatial variability based on research surveys in the 1995-1999 spawning seasons. Effects of environmental variability and abundance of zooplankton that serve as prey for larval bay anchovy were analyzed. In the years of these surveys, 97.6% of eggs and 98.8% of larvae occurred in the polyhaline lower bay. Median egg and larval abundances differed more than 10-fold for surveys conducted in the 5 yr and were highest in the lower bay. Within years, median larval abundance (ind. m-2) in the lower bay was generally 1-2 orders of magnitude higher than upper-bay abundance. Salinity, temperature, and dissolved oxygen explained 12% of the spatial and temporal variability in egg abundances and accounted for 27% of the variability in larval abundances. The mean, baywide growth rate for larvae over the 5 yr period was 0.75 ± 0.01 mm d-1, and was best explained by zooplankton concentration and feeding incidence. Among years, mean growth rates ranged from 0.68 (in 1999) to 0.81 (in 1998) mm d-1 and were fastest in the upper bay. We identified environmental factors, especially salinity, that contributed to broadscale variability in egg and larval production.