The increasing number of deer-vehicle collisions (DVCs) has had a significant impact on public safety. Scientific countermeasures require the systematization of DVC data. In Japan, however, DVC countermeasures are still insufficient due to the lack of DVC data systematization. The objective of this study was to review the progressive approach used for DVC data systematization in Germany, North America (Canada and the USA.), Sweden, and the United Kingdom. Additionally, we describe the prospect of DVC data systematization in order to develop scientific countermeasures in Japan.
The density of invasive alien mongooses on Amami-oshima Island has recently been controlled to a low level by trapping. Aiming for eradication, three dogs were specially trained to detect the location of the animals to improve the efficiency of trapping. The detection efficiency of the dogs was higher than the efficiency of sensor cameras and pipe-type kill traps in each area, which had different mongoose densities. It was also significantly higher in high density areas (p<0.05) and higher than those methods plus hair traps in lower density areas. Dogs could also contribute to capture by handlers. The capture rates of the dog handlers were lower than those of the pipe traps in higher densities areas. However, a mongoose was caught by a dog handler in an area where none had been caught in the past five years. It was revealed that detection dogs are a sensitive means that have the potential for capture by the handler. While it takes a few years to train a detection dog. The area that one pair of a detection dog and a handler could scan thoroughly in a year was estimated at 16-28 km^2. The utilization of detection dogs preferentially in extremely low density areas is considered to be efficient.
A nationwide interview survey was conducted from 2009 to 2013 to evaluate the state of sea turtle bycatch in Japanese coastal fisheries. A total of 1,074 fishermen and other industry representatives were interviewed at 175 sites, and 2,087 responses regarding the various fishing methods used were collated. Bycatch frequency of more than 5-10 sea turtles annually per operation was reported in large and small pound net, gill net, bottom trawl, boat seine, surround net, rod and line, and trawl fisheries. The highest bycatch frequency was reported from large pound net fisheries, especially in the Pacific coast of Shikoku, followed by the East coast of Ki-i Peninsula. However, bycatch frequency among large pound net fisheries varied widely by operation. Bycatch mortality rate in large pound nets were also divided, with 30 of 40 valid respondents reporting low or nearly 0% mortality rate, while 5 respondents reported high or nearly 100% mortality rate. Small pound nets also demonstrated a relatively high bycatch frequency, although lower than large pound nets. The findings of this study suggest that the priority for addressing sea turtle bycatch in Japan should be placed on individual large pound nets with high sea turtle mortality. However, mitigation measures for coastal fisheries bycatch should be developed to ensure fish landings, especially since sea turtle nesting activities in Japan are increasing and exhibiting recovery from past trends.
We studied the circumstances and cause of a sudden mass mortality of frogs that occurred in May 2012 in Kurotanigawa, Tadami, Fukushima Prefecture. A total of 341 dead frogs of four species were observed: (Rhacophors arboreus, Rhacophors schlegelii, Rana nigromaculata, and Hyla japonica). Most of the dead individuals (91.8%) were forest green tree frog (Rhacophors arboreus). Based on pathological and molecular biological examination for pathogen, the primary cause of death appeared to be mammalian bites. We concluded that a mammalian predator caused this mass mortality by attacking. Automatic cameras provided evidence of raccoon dog (Nyctereutes procyonides), civet (Paguma larvata), and raccoon (Procyon lotor). The injuries to the frogs were consistent with reports of damage by raccoons. Raccoons may cause this mass mortality of frogs.