Innovation in small-scale aquaculture in Chile

In light of the current depletion of extractive marine resources and the sustainability issues that have arisen in the aquaculture industry, the small-scale aquaculture sector has emerged as a viable and sustainable alternative for generating income. To integrate the small-scale aquaculture sector into the food value chain, understanding the decision-making process to innovate becomes essential. This paper explores the factors underlying both innovation choices and intensity among small-scale aquaculture producers by utilizing exclusive census data from the small-scale aquaculture sector in Chile. The results indicate that education, secure property rights, internet access, participation in organizations, commercialization methods, government instruments, understanding of credit, and social learning promote innovation decisions. We also find that largest producers innovate in more areas, suggesting a role of size for both technological and non-technological innovations.     

Loss of host fidelity in highly inbred populations of the parasitoid wasp <Emphasis Type="Italic">Aphidius ervi</Emphasis> (Hymenoptera: Braconidae)

Inbreeding frequently reduces the fitness of organisms, but little is known about how this phenomenon can affect the biological control. Host fidelity provides an adaptive advantage to aphid parasitoids, allowing females to find their aphid host more quickly in heterogeneous environments. This trait is mediated by the learning of signals, mainly chemical cues emitted from the host in which parasitoids developed (natal). This article is aimed at studying whether host fidelity can be altered after many generations of inbreeding reproduction in caged laboratory populations, for which host preference and fitness parameters were measured in the parasitoid wasp Aphidius ervi. Also, the effect of the natal/non-natal hosts was studied, using parasitoids originated from the pea aphid (Acyrthosiphon pisum) and the grain aphid (Sitobion avenae). We observed a loss of host fidelity in the studied A. ervi populations, irrespective of their natal aphid host, which contrasts with previous reports showing preference for natal hosts in outbred laboratory populations. The loss of host fidelity is discussed in terms of the origin of populations; the sex ratio was strongly biased toward males and long-time maintenance under laboratory conditions. Our results highlight the need for controlling the genetic diversity of caged parasitoids before they are released into fields, as a long period of inbreeding could negatively affect the biological control.     

Forage yield and chemical composition of canola (Brassica napus L.) as affected by sowing methods

The sowing method of spring‐type canola (Brassica napus L. var. oleifera) for forage has a major influence on its productivity and agronomic management. A field experiment was conducted in Matamoros, Coahuila, Mexico, during two growing seasons (2008–2009 and 2009–2010) to determine dry matter (DM), crude protein (CP) and net energy for lactation (NE_L) yields, as well as canola forage chemical composition as a function of six sowing methods. The treatments assessed were broadcast sowing and five different row spacings: 0·19, 0·38, 0·57, 0·76 and 0·95 m (double row, 0·20 m apart). In the first year, with a mean growing season temperature of 17·2°C, sowing methods did not affect DM yield, but CP and NE_L content and yield were higher in 0·19‐m row spacing. The mean temperature in the second year (13·5°C) was slightly lower than the long‐term mean (14·8°C) in the region, resulting in the highest DM (8840 kg ha^?1), CP (2486 kg ha^?1) and NE_L yields (51 103 MJ ha^?1) with 0·19‐m row spacing. In row‐sowing methods with over 0·19‐m row spacing, DM, CP and NE_L yields decreased by 19·3–39·7, 20·4–42·1 and 21·2–42·7% respectively. Results indicate that sowing methods significantly affected canola forage productivity.     

Identification of genomic islands in Chilean Piscirickettsia salmonis strains and analysis of gene expression involved in virulence

Piscirickettsia salmonis, an agent of Piscirickettsiosis, is the cause of major losses in the Chilean salmon industry. We identified, characterized and bioinformatically analysed genomic islands in field strains of P. Salmonis, using the bioinformatic software PIPS, that uses the characteristics of the islands of pathogenicity to identify them. We analysed nine partially sequenced genomes in different new field strains, and compared them with the LF‐89 (Type strain) genome, selecting a genomic island present in all of them. We then evaluated the relative expression of three genes present in that island. From the obtained results, we conclude that the expression of the tcf gene is directly proportional to the cytopathogenicity in vitro of the bacteria; the product of the dnsa gene could contribute to its pathogenicity, but would be potentiated by one or more factors. The product of the gene liso is necessary for the virulence process and could have functions in early stages of infection. Regarding the strains, the IBM‐040 strain showed a significant increase in the expression of all the genes in the study. Contrarily, LF‐89 only presented a significant increase in expression of the gene liso, which correlates with the cytopathogenicity in vitro observed in the SHK‐1 cells.     

Science,capacity building and conservation knowledge: The empowerment of the local community for marine conservation in Rapa Nui

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Driving factors of synchronous dynamics in brown trout populations at the rear edge of their native distribution

The classical debate about the roles of endogenous factors and external drivers in regulating populations continues to be a very active area of scientific research, and these roles are even more complex in populations located in geographically marginal areas. We tested three hypotheses on two separate brown trout populations inhabiting the southernmost basins of the Iberian Peninsula, with the aims of determining the relationships among (a) rainfall and air temperature for each season preceding fish sampling and the observed age group densities; (b) environmental synchrony and density synchrony for all possible pairs of sites; and (c) physical habitat similarity and the similarity of the density response to climatic drivers among pairs of sites. For this purpose, demographic series (98 surveys at 14 sampling sites), climatic conditions (rainfall and air temperature) and site habitat characteristics (physiogeographic and quality index values) were analysed between 2006 and 2014. The results show how the synchrony in the study populations is the result of a Moran effect directed mainly by winter precipitation and conditioned by the habitat similarity (highlighting the altitude, the distance to the upper limit and IHF index, along with the Euclidian distance among pairs of sites of the whole set of habitat variables). Preserving the heterogeneity of these habitat characteristics will increase the resilience of trout populations that inhabit this rear edge of distribution. The current context of global climate warming predicts extremely drastic changes in the dynamics of external drivers that regulate the trout populations in the study region.     

Are mussel seed producers responsive to economic incentives? Empirical evidence from the Benthic Resource Management Areas in Chile

We specify a model to analyze the participation and supply decisions of coastal producers performing with mussel seed uptake. We empirically specify and estimate the model for a sample of artisanal fishermen in Southern Chile, using a panel data set between 2008 and 2013. This period presents large changes in producer engagement and supplied quantities. The results suggest that temporal changes in supply are mainly explained by price, cost, and contract variables. Moreover, socioeconomic variables help to explain the differences between different producer groups. We conclude that seed uptake is dependent on supply conditions and the development of the external market and that policies aiming to promote previous activity should consider the interdependence between the markets.     

Effects of including shrimp protein hydrolysate in practical diets on the growth and survival of redclaw crayfish hatchlings Cherax quadricarinatus (Von Martens, 1868)

An experiment was carried out to analyse the effects of substituting fish‐meal (FM) with soya bean meal and shrimp protein hydrolysate (SPH) on the percent survival, growth rate, feed efficiency and molt frequency of redclaw crayfish hatchlings, Cherax quadricarinatus. The experiment was performed in a closed recirculating‐water system over a 56‐day period. Five diets were tested: a control diet (SPH₀) comprising 100% FM without SPH, and four diets with 2.5%, 5.0%, 10.0% and 15.0% SPH substitution (diets SPH_2.5, SPH₅, SPH₁₀ and SPH₁₅ respectively). Analysis of water quality indicated that it was adequate to maintain a good growth and survival of hatchlings. The results showed that 100% survival was obtained for hatchlings fed with SPH₅, SPH₁₀ and SPH₁₅ diets. Higher mean values of final weight were obtained for the SPH₅ diet. The highest weight gain was observed in SPH_2.5 and SPH₅ diets. Hatchlings showed similar specific growth rates for all diets. The efficiency rate of the SPH₁₅ diet was lower compared to the other diets. Overall, individual feed consumption was higher in hatchlings fed diets of SPH₅ and SPH₁₅. It is recommended that 5.0% of SPH could be included in diets of hatchling redclaw crayfish to improve their growth efficiency.