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The survival rate of butterflies in the wild

What Explains the Low Survival Rate of Developing Country Export Flows? [electronic resource]

Successful export growth and diversification require not only entry into new export products and markets, but also the survival and growth of export flows. This paper uses a detailed, cross-country dataset of product level bilateral export flows to illustrate that exporting is an extremely perilous activity and especially so in low-income countries. The authors find that unobserved individual heterogeneity in product-level export flow data prevails despite controlling for a wide range of observed country and product characteristics. This questions previous studies that have used the Cox proportional hazards model to model export survival. The authors estimate a Prentice-Gloeckler model, amended with a gamma mixture distribution summarizing unobserved individual heterogeneity. The empirical results confirm the significance of a range of products as well as country-specific factors in determining the survival of export flows. From a policy perspective, an interesting finding is the importance of learning-by-doing for export survival: experience with exporting the same product to other markets or different products to the same market are found to strongly increase the chance of export survival. A better understanding of such learning effects could substantially improve the effectiveness of export promotion strategies.

Online World Bank eLibrary

Comparing the survival rate of juvenile Chinook salmon migrating through hydropower systems using injectable and surgical acoustic transmitters [electronic resource]

Acoustic telemetry is one of the primary technologies for studying the behavior and survival of fishes throughout the world. The size and performance of the transmitters is still the key limiting factor despite that considerable effort has been expended to understand the biological effects of implantation of acoustic transmitters in yearling and subyearling Chinook salmon. The newly developed injectable transmitter is the first active acoustic tag that can be implanted via injection instead of surgery. It also lasts more than four times longer than the commercially-available transmitters. A two-part field study was conducted to evaluate the performance of the injectable transmitter and its effect on the survival of implanted fish. The injectable transmitter performed well and similarly to the other commercially-available transmitters tested. Snake River subyearling Chinook salmon smolts implanted with the injectable tag had a higher survival probability from release to each of 11 downstream detection arrays than concurrent releases of fish surgically implanted with commercially-available tags. In addition, reach-specific survival estimates were significantly higher for the injectable group in three of the eleven reaches examined. Overall, the injectable group had a 0.263 (SE = 0.017) survival probability over the entire 500 km study area compared to 0.199 (0.012) for the surgically implanted group. The differences in survival may have been caused by warm water temperatures and higher rates of infection experienced by the surgically implanted group due to the presence of sutures acting as an attachment site for pathogens. The reduction in size and ability to implant the new transmitter via injection has further reduced the tag or tagging effect bias associated with studying small fishes. As a result, the information gathered with this new technology is helping minimize the impact of dams on fish, leading to more environmentally sustainable energy systems.

Online OSTI