Anesthesia during Vaccination of Atlantic Salmon: Compliance with Recommended Procedures

The preparation and use of two anesthetic agents for fish, a buffered metacaine solution for anesthesia in connection with vaccination procedure, and an available benzocaine solution for minor procedures, were studied at a commercial fish farm producing Atlantic salmon, Salmo salar L., smolts. The procedures were compared with the given recommendations to evaluate compliance with recommended procedures and labels. The personnel were evaluated to be non‐compliant with labels and procedures for both anesthetic agents used and the recommended exposure time in the baths. Five important themes were identified: the preparation and use of the anesthetics, fish welfare, training procedures, and occupational hazard aspects. One important reason for non‐compliance was that the rate of delivery of anesthetized fish to the vaccination table was more dependent on the speed of vaccination, and less on the anesthetic depth of the fish. This may be a management issue. Management decisions may create an environment leading to situations where errors are more likely to occur. Better communication between the fish health‐service team and the personnel, more tailored procedures, and a preprepared anesthetic agent might increase compliance with procedures and may promote fish welfare and welfare of the employees.     

Effects of adult stocking density on egg production and viability in cultures of the calanoid copepod Acartia tonsa (Dana)

The effect of stocking density of the calanoid copepod Acartia tonsa was evaluated in a 96 h rearing experiment. Possible density‐dependent egg production and egg viability were analysed at stocking densities of 100, 200, 300, 400 and 600 adults L⁻¹. Temperature, oxygen saturation and algal concentration were kept optimal. A non‐density‐dependent mortality rate of 15–19% day⁻¹ was documented. A non‐significant density‐dependent egg production was observed between 100 and 600 adults L⁻¹. The average egg production was 22.5±8.8 egg female⁻¹ day⁻¹ in all densities. The average egg hatching success was 84.7±4.8% and was never observed below 76.1%, with no significant differences across the stocking densities. Conclusively, as a practical recommendation for the aquaculture industry, copepod cultures with densities ranging from 100 to 600 adults L⁻¹ and presumably even more dense cultures are possible with the studied species obtaining a steady egg production and still high egg viability.     

Accelerated extractions of North Atlantic cod and herring, 1520–1790

We propose the concept of Accelerated Marine Extraction to signify two periods when rapidly increasing cod (Gadus morhua, Gadidae) and herring (Clupea harengus, Clupeidae) fisheries, c.1540–1600 and c. 1730–1790, exceeded human demographic growth. Total landings vastly exceeded previous assessments and more than doubled between 1520 and 1620 from about 220,000 metric tonnes (t) to 460,000 t. Supplies of cod and herring to the European market peaked in 1788 at more than 1 million t before the unrest connected with the French Revolution brought many fisheries to a temporary halt. Accelerated Marine Extractions increased European food security at times of human demographic growth by almost doubling the supplies of fish protein per capita. While herring was the most important species by 1520, cod dominated through the period 1540–1790, and the trajectories of cod and herring extractions differed significantly. Cod landings increased almost ten-fold between 1520 and 1790, driven by strong and sustained landings in the Northwest Atlantic. Herring landings remained stable through the 16th century but declined severely through the next 150 years. However, from 1750, herring landings quadrupled, largely because of Swedish west coast fisheries. The results fundamentally shift our understanding of the scale of Atlantic fisheries in the past and underline the role of marine resources for European societies.     

Can timing of spawning explain the increase in egg size with female size in salmonid fish?

A common observation is that egg size increases with maternal size within populations. Several hypotheses have been proposed to explain this phenomenon. Most recently, it was suggested that the optimal egg size depends on female size due to correlations between (i) breeding time and egg size selection and (ii) female size and breeding time, and as such, the positive egg size–maternal size relationship represents an adaptive strategy. Here, we test the second of these two premises in two salmonid species, Atlantic salmon (Salmo salar) and coho salmon (Oncorhynchus kisutch) for which we have detailed breeding and egg size data. The body size of spawning females decreased throughout the season in coho salmon, but not in Atlantic salmon. Furthermore, we did not find a direct correlation between egg size and breeding time, which would also be expected if this premise was correct. Accordingly, breeding date does not appear to be as important as other factors in shaping among female differences in egg size.     

Predation on native fish eggs by invasive round goby revealed by species‐specific gut content DNA analyses

1. Conservation of riverine fish often aims to improve access to spawning grounds and restore longitudinal connectivity by removing migration barriers, and involves substantial investments. However, these investments also enable non‐native predators to invade upstream into spawning areas and potentially adversely affect the recruitment of threatened freshwater fish through egg or fry predation.
2. Detecting egg predation is often challenging. Visual inspections of fish gut contents may underestimate predation of soft materials such as eggs and fry, which limits the discovery of predators preying upon these life‐stages. DNA‐based detection assays may offer a more sensitive tool to assess predation of soft materials.
3. A conservation issue was confirmed by developing and applying a species‐specific DNA‐based detection assay: invasive round goby (Neogobius melanostomus) prey on the eggs or fry of the threatened common nase (Chondrostoma nasus) in Switzerland.
4. DNA‐based detection assays were also developed for five other valuable native fish species, including endangered salmonid and cyprinid river spawners. The applicability of the assays was confirmed in a series of laboratory and field feeding experiments involving eggs and fish tissue. In addition, this work provides a guiding framework for conservation managers regarding the use and applicability of different DNA‐based detection approaches for gut content analysis.
5. The results of this study could inform local conservation measures – such as temporary reductions in the density of round goby at spawning sites prior to spawning – and demonstrate how targeted application of species‐specific molecular markers may advance freshwater fish management.

     

Goldrush: A new high quality russet-skinned potato cultivar

On March 1, 1992, the North Dakota Agricultural Experiment Station announced the release of a new russet potato cultivar named Goldrush. Goldrush is an oblong, smooth, russet-skinned potato cultivar that has very white flesh, good culinary quality, resistance to hollow heart and is adapted for both the fresh and processing market.     

Russet Nugget: A fresh market and processing potato cultivar with resistance to common scab

Russet Nugget is an oblong, smooth, high yielding potato with fresh market and processing qualities. It emerges quickly, produces an erect, large, vigorous vine with a profusion of white flowers, and is late maturing. Russet Nugget is very resistant to common scab, and moderately resistant to leafroll net necrosis,Vertcillium wilt, and early blight (tuber and foliage). In the San Luis Valley of Colorado, yield of Russet Nugget is comparable to Russet Burbank, with a significantly greater percentage of U.S. No. 1 tubers. In Texas, total yield is comparable to Norgold 40, with a slightly lower percentage of U.S. No. 1 tubers. Tubers of Russet Nugget have high specific gravity and vitamin C content.     

Pedigree Reconstruction with Genome-Wide Markers in Potato

Reliable pedigree information facilitates a scientific approach to breeding, but errors can be introduced in many stages of a breeding program. Our objective was to use single nucleotide polymorphisms (SNPs) to check the pedigree records of elite North American potato germplasm. A population of 719 tetraploids was genotyped with an Infinium SNP array, yielding 5063 high-quality markers. Based on pedigree records, the dataset contained 198 parent-offspring trios, of which 182 were consistent with the marker data. For 13 of the 16 trios with a pedigree error, the true parent was identified in the population. By comparing the additive relationship matrix calculated from pedigree with the genetic distance calculated from markers, an additional 24 pedigree modifications were proposed, including the paternity of several varieties developed with bulk pollen. To ensure accurate pedigree records are published in the future, we recommend that new varieties be SNP genotyped and checked against this dataset.