Separate, but related, to the issue of dead zones are fish kills, where large numbers of menhaden or other fish will turn up dead in a single area. According to the Virginia Institute of Marine Sciences, which investigates fish kills in the Chesapeake Bay, the causes of fish kills are varied, but often are related to environmental factors such as low amounts of oxygen in the water, algal blooms, and water temperatures that are either too hot or too cold. Other factors, such as the dumping hazardous materials or excess bycatch, can also contribute.