Fish aggregating devices in the eastern tropical Pacific marine corridor,according to the Colombian Fisheries Observer Program

1. Fish aggregating devices (FADs) are floating objects that facilitate the aggregation of fish; those that aggregate pelagic species such as tunas are of particular interest for artisanal and industrial fisheries.
2. Due to the increasing use of these devices worldwide, bodies responsible for the administration and management of fishery resources have proposed control and surveillance activities focused on the use of such devices. To achieve this, it is essential to have access to quality information, which is usually obtained through on-board observer programmes such as the Colombian Fisheries Observer Program.
3. Based on the historical records of this programme, and for the first time, the spatial–temporal distribution of the FADs in the eastern tropical sector of the Eastern Pacific Ocean is presented, analysing 166 records of tuna fishing operations carried out between 2009 and 2015. Of the 2,328 sets identified in the records, 957 corresponded to sets on FADs, of which 80.56% were effective and caught 12,246 tons of tuna.
4. The number of sets of FADs increased over time, representing approximately 86.9% of the sets recorded in 2015, compared to 4.8% of this type of set recorded in 2009, with the Eastern Tropical Pacific Marine Corridor being the area of greatest concentration of sets.
5. Considering that the Eastern Tropical Pacific Marine Corridor was designed to promote the conservation and sustainable use of biological diversity in the Eastern Tropical Pacific, this study highlights the need to include as a research priority, the potential effect that aggregation devices may have on the biological connectivity processes present in the corridor, as well as on the dynamics of large pelagic fish populations of commercial interest.
6. In terms of management of FADs, it is recommended that a precautionary approach be adopted and that regulations related to the maximum number of FADs per vessel be adjusted according to their Inter-American Tropical Tuna Commission class, in addition to assigning a maximum number of sets per vessel.

     

Nitrous oxide (N<Subscript>2</Subscript>O)-reducing denitrifier-inoculated organic fertilizer mitigates N<Subscript>2</Subscript>O emissions from agricultural soils

The only known sink for nitrous oxide (N₂O) is biochemical reduction to dinitrogen (N₂) by N₂O reductase (N₂OR). We hypothesized that the application of N₂O-reducing denitrifier-inoculated organic fertilizer could enhance soil N₂O consumption while the disruption of nosZ genes could result in inactivation of N₂O consumption. To test such hypotheses, a denitrifier-inoculated granular organic fertilizer was applied to both soil microcosms and fields. Of 41 denitrifier strains, 38 generated ³⁰N₂ in the end products of denitrification (³⁰N₂ and ⁴⁶N₂O) after the addition of Na¹⁵NO₃ in culture condition, indicating their high N₂O reductase activities. Of these 41 strains, 18 were screened in soil microcosms after their inoculation into the organic fertilizer, most of which were affiliated with Azospirillum and Herbaspirillum. These 18 strains were nutritionally starved to improve their survival in soil, and 14 starved and/or non-starved strains significantly decreased N₂O emissions in soil microcosms. However, the N₂O emission had not been decreased in soil microcosms after inoculating with a nosZ gene-disruptive strain, suggesting that N₂O reductase activity might be essential for N₂O consumption. Although the decrease of N₂O was not significant at field scales, the application of organic fertilizer inoculated with Azospirillum sp. TSH100 and Herbaspirillum sp. UKPF54 had decreased the N₂O emissions by 36.7% in Fluvisol and 23.4% in Andosol in 2014, but by 21.6% in Andosol in 2015 (H. sp. UKPF54 only). These results suggest that the application of N₂O-reducing denitrifier-inoculated organic fertilizer may enhance N₂O consumption or decrease N₂O emissions in agricultural soils.     

Effect of dietary crude protein level on growth performance,blood characteristics,and indicators of intestinal health in weanling pigs

An experiment was conducted to test the hypothesis that reducing crude protein (CP) in starter diets for pigs reduces post-weaning diarrhea and improves intestinal health. In total, 180 weanling pigs were allotted to 3 diets containing 22, 19, or 16% CP. Fecal scores were visually assessed every other day. Blood samples were collected from 1 pig per pen on days 1, 6, 13, 20, and 27, and 1 pig per pen was euthanized on day 12. Results indicated that reducing dietary CP reduced (P < 0.01) overall average daily gain, gain to feed ratio, final body weight, and fecal scores of pigs. Pigs fed the 16% CP diet had reduced (P < 0.01) serum albumin compared with pigs fed other diets. Blood urea nitrogen, haptoglobin, interleukin-1β, and interleukin-6 concentrations in serum were greatest (P < 0.01) on day 13, whereas tumor necrosis factor-α and interleukin-10 concentrations were greatest (P < 0.01) on day 6. Villus height in the jejunum increased (P < 0.05) and crypt depth in the ileum was reduced (P < 0.01) if the 19% CP diet was fed to pigs compared with the 22% CP diet. A reduction (P < 0.05) in mRNA abundance of interferon-γ, chemokine ligand 10, occludin, trefoil factor-2, trefoil factor-3, and mucin 2 was observed when pigs were fed diets with 16% CP. In conclusion, reducing CP in diets for weanling pigs reduces fecal score and expression of genes associated with inflammation.