Dolphins numbers still in decline despite efforts of fisheries

Eastern Pacific dolphin populations were expected to increase after so-called “dolphin safe” practices were adopted to reduce fishing “bycatch” deaths in which the marine mammal is unintentionally caught.

A new study reveals that while direct mortalities have been reduced, depleted dolphin populations have failed to recover as a result of a reproductive decline related to past fishing activities. The northeastern pantropical spotted dolphin is primarily affected. It’s also noted that the eastern spinner dolphin is in decline, but a direct link to fishing is inconclusive.

The work was done by researchers at Scripps Institution of Oceanography and the National Oceanic and Atmospheric Administration’s Southwest Fisheries Science Center.

Learning from flies

A species of fruit fly from the Seychelles Islands often lays larvae instead of eggs. The discovery, by UCSD biologists, is so surprising that the scientists initially thought it was a mistake, but have verified that highly developed larva emerge within two hours of being laid compared to nearly 23 hours for 10 other species in the study. Early hatching offers advantages. Mobile larvae can burrow into the ground to avoid becoming a predator’s meal or host to the eggs of parasitic insects.

Why females of this species, and not others, retain their fertilized eggs until they are ready to hatch remains a mystery for now. The fly is one of a dozen species of Drosophila whose genomes have been sequenced; information that should shed light on the genetic changes responsible for this evolutionary reproductive change.

Seismic simulations

A team, led by researchers at the San Diego Supercomputer Center at UCSD, has successfully completed record-setting simulations of the earth’s inner structure, paving the way for seismologists to model seismic wave propagation at frequencies of just over one second - the same frequencies that occur in nature.

That is the shortest wave period ever obtained in seismic wave propagation and, in the world of supercomputing, shatters the previous two-second run record. The research qualified as a finalist for the prestigious Gordon Bell Prize, awarded annually for outstanding achievement in high-performance computing applications.

The research is crucial in helping seismologists better understand the dramatic differences in the complex structure of the Earth’s inner core, which appears to be anisotropic, or having unequal physical properties along different axes, with dramatic differences between its eastern and western hemispheres.