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Humpback Whale Migration Update: March 3, 1999

Today's Report Includes:

Greetings from Stellwagen Bank National Marine Sanctuary
March has come in like a lamb here in Massachusetts, although February went out like a lion with a major snowstorm on Thursday the 25th. No sightings of whales up here, but reports from the breeding and calving grounds have been positive.

News from the Humpback Wintering Grounds
Good weather and lots of whales have created excellent whalewatching conditions lately in the whales' wintering grounds in the Dominican Republic's Samana Bay (19 N, -69W) . Kim Beddall, owner of Victoria Marine and Whale Samana (two whalewatching companies in Samana Bay) notes that there are many surface active groups of 8-10 whales. Within these groups, many males are competing for each potential mate. Along with these competitive groups, she has seen some interesting behaviors, including one whale that spyhops (puts its head vertically out of the water past its eye) and then spins 360 degrees. Kim says the whales came in slowly to Samana Bay, but now there are lots of mothers and calves.

Too Close for Comfort?
Whalewatching in Samana Bay has undergone a major overhaul. According to Kim, boat operators are behaving themselves and following regulations quite nicely this season. The set of regulations was developed cooperatively by government, nongovernmental organizations, industry representatives, and scientists. In order to whalewatch, the commercial whalewatch vessel must have a permit and agrees to certain speed limits, approach distances, and a time limit for watching any one whale. Kim reports that the Dominican Navy recently prevented a private boater from continuing to use his boat after he was found to have entered the protected waters to whalewatch without a permit.

Challenge Question #5
"Knowing what you do about humpback whales, what do you think the speed limits, approach distances, and time limits are? Explain the reasoning behind your answers."

(To respond to this question, please follow the instructions below.)

  • Check out the interesting information about Samana Bay in the Dominican Republic, their whales, and whalewatching.

Food, Food, Food: Discussion of Challenge Question #3
Challenge Question #3 asked why all of the whales would congregate around the Caribbean, but divide up on their way to the feeding grounds.

Food, food, food said students in NY, MN, CA and ON. Explained Shaddy of Edison Elementary in Buffalo, NY: "I think that the whales would separate so that they can find enough food. If they all feed at the same place they might exhaust their food supply." (

Exactly right: By separating into different feeding grounds, the whales maximize their opportunities to obtain food and reduce competition. The population in each summer feeding ground increases as mothers bring their calves (male and female). As they grow, the calves return to this same feeding ground. For example, "Salt" (one of the first recognized whales at Stellwagen Bank) has continued to bring her calves back, and her female calves are now bringing THEIR calves back to the Bank--Salt's grandchildren! So, because the whales divide into separate populations, if one feeding area were to be low in prey (or some environmental or human-caused calamity were to affect the ecosystem), the entire western North Atlantic stock would not be at risk -- only the local population.

When they are up north at Stellwagen Bank, which has a nice sandy surface, they are feeding primarily on sand lance -- a small bait fish which is also called the sand eel. Obviously, by its name, the fish likes sandy habitats where it digs itself into the sediments to hide. The fish is about 5-6 inches long and pencil thin. Out of the sand, these fish often crowd into large schools or "balls," making feeding quite efficient for the humpback whales.

Elsewhere in the Gulf of Maine, where sandy bottoms are not as prevalent, humpbacks may be feeding on herring, mackerel, and other small fish, as well as krill and squid. If these prey items are on Stellwagen, the whales will eat them too. Down in the Caribbean the whales are not eating.

There's also another reason which no one thought of: The humpbacks have devised an excellent strategy which decreases inbreeding and assures that the gene pool stays healthy. If small groups of whales were to keep breeding amongst themselves, any unhealthy traits would be exacerbated -- and passed along. By bringing many individuals together, humpback males and females have fewer chances of mating with close relatives.

Migration Delays in the Pacific: Discussion of Challenge Question #4
Challenge Question #4 concerned the possible delays in humpback and gray whale migrations this year, especially in the Pacific. There is no real answer for this -- only supposition at this time--but the students at Scott Young Public School in Ontario are good at thinking through the possibilities:

"The El Nina effect this year is confusing the whales. Maybe their food supply is high this year, so they are staying where they are," said Ryan & Stephen of grade 5.

It may be that the El Nino/La Nina phenomenon has created warmer water, which led to a timetable change for the whales. Or it may not. Perhaps in the big scheme (over 25 or 50 years), this is the regular migration schedule -- and what we were seeing in the past few years was the aberration. Or it may be that the whales are fickle in their adherence to migration deadlines. Perhaps they came upon sources of food that they found too tempting to pass up -- so they took extra time to feed before making the migration.

Whatever the cause of the delay in the arrival of whales to the Hawaiian Island Humpback Whale National Marine Sanctuary, the numbers now are as solid as ever. The official humpback whale shoreside counts on Oahu (2/27) and Hawaii (the Big Island) (2/20) were 119 and over 300, respectively. The population of whales around the Hawaiian Islands is estimated at about 2,000, so a count of over 400 (more than a fifth of the population) is excellent. Researchers doing aerial surveys on the 25th also counted over 1,000 other marine mammals, including spinner, spotted, roughtooth and bottlenose dolphins, pilot whales and false killer whales.

The shoreside counts were done from 15 stations on the Big Island and 31 stations on Oahu. These stations were located on high points around Oahu and primarily on high points along the western side of the Big Island.

Challenge Question #6
"Why would they want to place the shoreside whale spotting stations on high points? And why might the greatest concentrations of whales have been spotted on the northwest side of the Big Island, and off the east and southeast sides of Oahu? (Hint: You may want to look at a bathymetric map of the Islands.)

(To respond to this Challenge Question, please follow the instructions at the end of this report.)

That's it for this week. This is Anne Smrcina, education coordinator of the Stellwagen Bank National Marine Sanctuary, signing off.

How to Respond to Today's Humpback Whale Challenge Questions:

Please answer ONLY ONE question in each e-mail message!

1. Address an E-mail message to:

2. IMPORTANT: In the Subject Line of your message write: Challenge Question # 5
(Or Challenge Question # 6 )

3. In the body of the EACH message, give your answer to the question above.

The Next Humpback Whale Migration Update will Be Posted on March 17, 1999.

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