Week 7: Humpback Whale Conservation
Humpbacks are Protected (for Now...)
Although humpback whales are still listed as an endangered species by the U.S. Endangered Species Act (1972), many populations of humpback whales appear to be recovering from years of intensive and destructive whaling practices that decimated this and other species of whales. In the twentieth century, some 200,000 humpback whales were killed in the Southern Hemisphere alone.With an estimated 95% of the population wiped out, humpback whales finally gained protection from whaling in the North Pacific in 1966.
With humpback whale populations increasing from the cessation of whaling, it is very likely that humpbacks will be hunted again in the near future. Currently, the resumption of commercial whaling is a hot issue and one that is not easily solved.The Japanese have already threatened to expand their hunting quotas to include taking humpback whales in the Southern Oceans again. Unfortunately for many, it is probably only a matter of time before humpback whales are legally hunted again.
How Many Humpback Whales are there in the North Pacific?
From 2004-2007, nearly 400 researchers (including researchers from WhaleTrust) from ten different countries worked together to photo-identify humpback whales throughout the North Pacific Ocean to determine current population estimates. This project was called SPLASH, which stands for Structure of Populations, Levels of Abundance, and Status of Humpback Whales. Results indicate that the North Pacific population of humpbacks has increased to approximately 18,000-21,000 whales, with 50% of this population migrating to Hawaii each winter.
Threats to Humpback Whales
Natural predators for humpback whales, as well as most other species of cetaceans, include transient killer whales (that is, killer whales that feed primarily on other marine mammals) and aggressive species of sharks such as tiger sharks. However, these predators usually prey on sick, vulnerable or young whales, such as calves or yearlings rather than healthy or strong individuals.
Despite growing populations, humpback whales are still threatened by a variety of different factors, mostly anthropogenic (or human induced) factors. Entanglement in fishing gear, declining fish stocks and human competition for limited food resources, climate change, underwater noise pollution (e.g., ship traffic, oil drilling, Navy sonar testing), environmental toxins (e.g., PCBs and DDT), as well as threats of resumed whaling practices continue to present threats to recovering populations of humpback whales.
Perhaps the most alarming cause for concern is the collective impact of all these factors on whales, and our limited knowledge and understanding of how they will directly affect the survival and continued recovery of humpbacks into the next generation.
Ship Strikes and Entanglement: On the Rise?
With increasing populations of humpbacks whales and bigger and faster boats, whale collisions and ship-strikes are a growing concern for nearshore whale populations. During the 2005-2006 and 2006-2007 seasons, there were a total of 12 confirmed ship-strikes (six in each season) on humpback whales in Hawaiian waters. Of course, these numbers reflect only the number of confirmed reports; that is, the one's that were both reported and verified or confirmed. Entanglement in fishing gear is also a global concern for many species of whales. During 2006 and 2007, there were seven confirmed reports of entangled humpback whales in Hawaii, and scar analysis on humpback whales in Hawaii suggests that 33% have recently been entangled. Similar trends exist on feeding grounds. From 1997-2004, 52 humpback whales were reported as entangled in fishing gear in Alaska.
Although these numbers appear to be growing, it is unclear whether or not this reflects a real trend in an increasing number of ship-strikes and entanglement or whether there is more awareness and therefore an increase in the number of collisions or entanglements reported each year.
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