The North Atlantic northern right whale is headed for extinction unless human intervention improves survival, according to a study published Wednesday in the "Proceedings of the National Academy of Sciences."
Researchers at Woods Hole Oceanographic Institution and the University of Massachusetts, Boston, have completed a study estimating the probability of survival for this endangered whale population. Researchers plan to use the data to advise the shipping industry on how minimize the likelihood of collisions -- the major threat to the species.
Several thousand right whales once existed in the North Atlantic Ocean, but commercial hunting at the turn of the century severely depleted whale populations. For the past 60 years, the species has been protected. However, despite conservation techniques, right whale populations have never recovered. Their numbers are currently estimated at about 300.
The small population has allowed scientists to compile a catalog of photographs which enable individual animals, distinguished by unique markings, scars and callosity patterns, to be identified and tracked.
Scientists have recorded sightings annually since 1980 in calving areas in Florida and in waters off New England and into the Bay of Fundy in Nova Scotia. According to the report, over that time survival has declined dramatically and population growth rate has gone from positive to negative. Under current conditions, the population is headed for extinction in less than 200 years, the study shows.
"The right whale is at risk from entanglement in fishing gear, collisions with ships and pollution. The population seems to be recovering more slowly than other whale species, such as humpbacks. Why this is happening has not been documented. Until this study, no one suspected that the survival probability for northern right whales was going down or that the population was actually declining," said Senior Scientist Hal Caswell of the Woods Hole Oceanographic Institution Biology Department.
Caswell and study colleagues used the New England Aquarium database to estimate survival and discovered the probability of survival was declining over time. They then combined these data with an estimate of birth rate, which is also declining. Together, the numbers show a decline in the rate of growth of the entire population.
Most right whales are killed by collisions with ships, according to the National Oceanic and Atmospheric Administration. Slow moving in general, the whales are especially slow when accompanied by calves. With only the flat of their back visible at the surface, they are difficult to detect from large, fast moving vessels.
The report notes that the most effective way to improve the prospects for the whales is to reduce mortality. The research team's goal is to provide reliable models that can be used to choose targets for management intervention.
"The future is not as bleak as it may appear for the right whales, since a number of efforts are already under way to reduce their mortality rate," Caswell adds. "There is no question that reducing human-caused mortality is essential to the survival of the population. NOAA is at work to teach ship operators how to recognize and avoid right whales, and fishing grounds have been closed during certain periods in some areas frequented by the whales, such as Cape Cod Bay and Great South Channel."
New federal regulations, effective April 1, emphasize the development of whale-friendly fishing gear. They require gillnetters and lobster boats to avoid certain types of gear, and place bans on fishing in some areas in order to protect the whales. The National Marine Fisheries Service finalized rules to protect the endangered population in February. Officials hope that over time, as more people learn about how whales are entangled and how to prevent it, the population will start to rebound.
For more information, contact Shelley Lauzon, Woods Hole Oceanographic Institution, (508)289-2270, email: email@example.com.