Hawaiian Marine Protected Areas Produce Spillover

by Katie Huang

Marine protected areas (MPAs) can be beneficial to fisheries through spillover effects, which occur when protected fish stocks recover and migrate into open areas. As a result, fishers tend to react by increasing fishing pressure near MPA boundaries to capitalize on these biomass gradients. To supplement previous research on spillover, Stamoulis and Friedlander (2013) studied a Hawaiian MPA with a new seascape approach that incorporated habitat variables, multiple scales of study, and information on fishing pressure. They took visual surveys of fish populations both targeted and not targeted for conservation along random transects and determined their biomass, species abundance, and density in protected and open areas. The authors found that all fish wellbeing measures were observed to be significantly higher inside the reserve. Also, as distance increased from the MPA boundaries, biomass decreased for resource fish but remained constant for non-resource fish, indicating the existence of a spillover gradient. Although fishing was more concentrated near MPA borders, current harvest rates are sustainable for the time being. The authors suggest that similar comprehensive studies be made throughout Hawaii but that further research should also include analysis on larval and egg export, a second benefit to fisheries besides spillover. Continue reading

Heat Stress and Low Humidity with Climate Change will be Hard on Midwestern Corn Crops

 

by Christina Whalen and Emil Morhardt

Maize (corn) production continues to be a very important source of food, feed, and fuel all around the world, but climate change has raised the concern about being able to maintain the yield rates. A negative relationship between extremely high temperatures (above 30˚C) and yield has already been observed in various regions. Previous studies have not been able to demonstrate which mechanism causes the correlation between extreme temperatures and yield, thus it is possible that the relationship reflects the influence of another variable, such as precipitation rates. There are other possible explanations for the observed relationships. This study explores the mechanisms used in other studies that document the importance of extreme heat on rainfed maize using the process-based Agricultural Production Systems Simulator (APSIM). The study asks three main questions: can APSIM reproduce the empirical relationships—what farmers are seeing on the ground?; if so, what does APSIM imply are the key processes that give rise to these relationships?; how much are these relationships affected by changes in atmospheric CO2? Continue reading

Protecting Deepwater Fish Populations in Hawaii

by Katie Huang

Starting in 1998, specific types of marine protected areas (MPAs) called bottomfish restricted fishing areas (BRFAs) were implemented throughout Hawaii to address conservation concerns over deep-sea species. Although much research has been conducted on how MPAs benefit shallow reef fish populations, less is known about how protection affects deepwater ecosystems. Sackett et al. (2014) studied four BRFAs of differing ages to determine whether relative abundance, mean length, and species richness of seven commonly exploited species varied when compared to unprotected regions. The authors took video surveys along the deep sea floor in both types of areas and counted the number and type of fish in each. They found that mean fish length Continue reading