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Humpback Whales in Costa Rica

Marine
Typography
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Humpback Whales are regular visitors to our part of the world.

 

Humpback whales are well known for their long "pectoral" fins, which can be up to 15 feet (4.6 m) in length. Their scientific name, Megaptera novaeangliae, means "big-winged New Englander" as the New England population was the one best known to Europeans. These long fins give them increased maneuverability; they can be used to slow down or even go backwards.

 

Similar to all baleen whales, adult females are larger than adult males, reaching lengths of up to 60 feet (18 m). Their body coloration is primarily dark grey, but individuals have a variable amount of white on their pectoral fins and belly. This variation is so distinctive that the pigmentation pattern on the undersides of their "flukes" is used to identify individual whales, similar to a human fingerprint.

 

 

In the summer, humpbacks are found in high latitude feeding grounds, such as the Gulf of Maine in the Atlantic and Gulf of Alaska in the Pacific. In the winter, they migrate to calving grounds in subtropical or tropical waters, such as the Dominican Republic in the Atlantic and the Hawaiian Islands in the Pacific. The Arabian Sea humpback does not migrate, remaining in tropical waters all year.

 

Humpback whales travel great distances during their seasonal migration, the farthest migration of any mammal. The longest recorded migration was 11,706 miles (18,840 km), with a trek from American Samoa to the Antarctic Peninsula. One of the more closely studied routes is between Alaska and Hawaii, where humpbacks have been observed making the 3,000 mile (4,830 km) trip in as few as 36 days.

 

 

During the summer months, humpbacks spend the majority of their time feeding and building up fat stores (blubber) that they will live off of during the winter. Humpbacks filter feed on tiny crustaceans (mostly krill), plankton, and small fish and can consume up to 3,000 pounds (1,360 kg) of food per day. Several hunting methods involve using air bubbles to herd, corral, or disorient fish. One highly complex variant, called "bubble netting," This link is an external site. is unique to humpbacks. This technique is often performed in groups with defined roles for distracting, scaring, and herding before whales lunge at prey corralled near the surface.

 

In their wintering grounds, humpback whales congregate and engage in mating activities. Humpbacks are generally "polygynous" with males exhibiting competitive behavior on wintering grounds. Aggressive and antagonistic behaviors include chasing, vocal and bubble displays, horizontal tail thrashing, and rear body thrashing. Males within these groups also make physical contact, striking or surfacing on top of one another. These bouts can cause injuries ranging from bloody scrapes to, in one recorded instance, death. Also on wintering grounds, males sing complex songs that can last up to 20 minutes and be heard 20 miles (30 km) away. A male may sing for hours, repeating the song several times. All males in a population sing the same song, but that song continually evolves over time. Humpback whale singing has been studied for decades, but scientists still understand very little about its function.

 

Gestation lasts for about 11 months. Newborns are 13-16 feet (4-5 m) long and grow quickly from the highly nutritious milk of their mothers. Weaning occurs between 6-10 months after birth. Mothers are protective and affectionate towards their calves, swimming close and frequently touching them with their flippers. Males do not provide parental support for calves. Breeding usually occurs once every two years, but sometimes occurs twice in a three year span.

 


Habitat

 

During migration, humpbacks stay near the surface of the ocean.

 

While feeding and calving, humpbacks prefer shallow waters. During calving, humpbacks are usually found in the warmest waters available at that latitude. Calving grounds are commonly near offshore reef systems, islands, or continental shores.

 

Humpback feeding grounds are in cold, productive coastal waters.

 

Distribution

 

Humpback whales live in all major oceans from the equator to sub-polar latitudes.

 

 

In the North Pacific, there are at least three separate populations, and

 

  1. California/Oregon/Washington stock that winters in coastal Central America and Mexico and migrates to areas ranging from the coast of California to southern British Columbia in summer/fall;
  2. Central North Pacific stock that winters in the Hawaiian Islands and migrates to northern British Columbia/ Southeast Alaska and Prince William Sound west to Kodiak; and
  3. Western North Pacific stock that winters near Japan and probably migrates to waters west of the Kodiak Archipelago (the Bering Sea and Aleutian Islands ) in summer/fall. There is some mixing between these populations, though they are still considered distinct stocks.

 

In the Southern Hemisphere, the International Whaling Commission (IWC) This link is an external site. has designated seven major breeding stocks linked to seven major feeding areas. In Costa Rica, there is overlap with Northern Hemisphere humpbacks geographically, but they are not there at the same time. All Southern Hemisphere humpbacks share feeding grounds in the Antarctic south of 40°S and between 120°E and 110°W.

 

Based on the most recent status review of the humpback whale, the NOAA determined that the species consists of 14 DPSs. View a map showing the identification and distribution of these DPSs here.

 

Population Trends

 

Threats

 

Humpback whales face a series of threats including:

 

  • entanglement in fishing gear (bycatch)
  • ship strikes
  • whale watch harassment
  • habitat impacts
  • harvest

 

Humpbacks can become entangled in fishing gear, either swimming off with the gear or becoming anchored. We have observed incidental "take" of humpback whales in the California/ Oregon swordfish and thresher shark drift gillnet fishery. Potential entanglement from gear from several fisheries can occur on their long migration from Hawaii to Alaska. Humpbacks in Hawaii have been observed entangled in longline gear, crab pots, and other non-fishery-related lines.

 

Inadvertent ship strikes can injure or kill humpbacks. We have verified mortality related to ship strikes in the Gulf of Maine and in southeastern Alaska. Ship strikes have also been reported in Hawaii.

 

Whale watching vessels may stress or even strike whales. The Gulf of Maine stock is the focus of whale watching in New England from late spring to early fall, particularly within the Stellwagen Bank National Marine Sanctuary. The central North Pacific stock is the focus of a whale-watching industry on their wintering grounds in the Hawaiian Islands. The feeding aggregation in southeast Alaska is also the focus of a developing whale-watching industry that may impact whales in localized areas.

 

Shipping channels, fisheries, and aquaculture may occupy or destroy humpback whale aggregation areas. Recreational use of marine areas, including resort development and increased boat traffic, may displace whales that would normally use that area. In Hawaii, acoustic impacts from vessel operation, oceanographic research using active sonar, and military operations are also of increasing concern.

 

Japan has issued scientific permits in the Antarctic and in the western North Pacific in recent years. In 2009, the full JARPA II program commenced. Annual sample sizes for the full-scale research (lethal sampling) are set at 50 humpback whales. According the the IWC, Japan has refrained from taking humpback whales.

 

Conservation Efforts

 

Efforts to conserve humpback whales include:

 

 

Regulatory Overview

 

In 1946, the International Convention for the Regulation of Whaling regulated commercial whaling of humpback whales.

In 1966, the International Whaling Commission prohibited commercial whaling of humpbacks.

In June 1970, humpback whales were designated as "endangered" under the Endangered Species Conservation Act (ESCA). In 1973, the Endangered Species Act (ESA) replaced the ESCA, and continued to list humpback whales as endangered.

In April 2015, we proposed to revise the ESA listing of the humpback whale by identifying 14 DPSs and listing 2 DPSs as threatened and 2 as endangered (80 FR 22304). The other 10 identified DPSs were not proposed for listing. 

In September 2016, we revised the ESA listing for the humpback whale to identify 14 Distinct Population Segments (DPS), list 1 as threatened, 4 as endangered, and identify 9 others as not warranted for listing. We also issued two final rules governing approach of humpback whales in Alaska and Hawaii. The first re-codifies existing approach regulations in Alaskan waters under the ESA so they apply to both threatened and endangered humpback whales, and adds similar approach regulations under the MMPA to protect all humpback whales found off Alaska. The other is an interim final rule for approach regulations under the MMPA in Hawaiian waters to replace the previous regulations under the ESA. While the regulations are effective 30 days after their publication in the Federal Register, NOAA Fisheries is accepting public comment for 60 days after their publication and will publish a final rule in the future.

 

Under the MMPA, threats to humpback whales are mitigated by regulations implementing the Pacific Offshore Cetacean Take Reduction Plan and the Atlantic Large Whale Take Reduction Plan.

 

Taxonomy

Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Cetacea
Family: Balaenopteridae
Genus: Megaptera
Species: novaeangliae

Species Description

 

 

Weight:
25-40 tons (50,000-80,000 pounds; 22,000-36,000 kg);
newborns weigh about 1 ton (2,000 pounds; 900 kg)
Length:
up to 60 feet (18 m), with females larger than males;
newborns are about 15 feet (4.5 m) long
Appearance:
primarily dark grey, with some areas of white
Lifespan:
about 50 years
Diet:
tiny crustaceans (mostly krill), plankton, and small fish; they can consume up to 3,000 pounds (1360 kg) of food per day
Behavior:
breaching (jumping out of the water), or slapping the surface