Until recently, zoologists believed that all species of phocids (true seals), a pinniped family, use a different maternal strategy than do otariids (fur seals and sea lions), another pinniped family. Mother otariids use a foraging strategy. They acquire moderate energy stores in the form of blubber before arriving at breeding sites and then fast for 5 to 11 days after birth. Throughout the rest of the lactation (milk production) period, which lasts from 4 months to 3 years depending on the species, mother otariids alternately forage at sea, where they replenish their fat stores, and nurse their young at breeding sites. Zoologists had assumed that females of all phocid species, by contrast, use a fasting strategy in which mother phocids, having accumulated large energy stores before they arrive at breeding sites, fast throughout the entire lactation period, which lasts from 4 to 50 days depending on the species. However, recent studies on harbor seals, a phocid species, found that lactating females commenced foraging approximately 6 days after giving birth and on average made 7 foraging trips during the remainder of their 24-day lactation period.

    The maternal strategy evolved by harbor seals may have to do with their small size and the large proportion of their fat stores depleted in lactation. Harbor seals are small compared with other phocid species such as grey seals, northern ele- phant seals, and hooded seals, all of which are known to fast for the entire lactation period. Studies show that mother seals of these species use respectively 84 percent, 58 percent, and 33 percent of their fat stores during lactation. By comparison, harbor seals use 80 percent of their fat stores in just the first 19 days of lactation, even though they occasionally feed during this period. Since such a large proportion of their fat stores is exhausted despite feeding, mother harbor seals clearly cannot support all of lactation using only energy stored before giving birth. Though smaller than many other phocids, harbor seals are similar in size to most otariids. In addition, there is already some evidence suggesting that the ringed seal, a phocid species that is similar in size to the harbor seal, may also use a maternal foraging strategy.

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    The expenses related to sponsoring a conference can be immense. An organization sponsoring a conference can recoup these expenses through registration fees and partnership with the host hotel. As part of the partnership, the host hotel sets aside a block of rooms for conference attendees, with rooms available at a slightly higher-than-normal rate.

    While most conference attendees prefer to stay in the host hotel, they often follow an alternate strategy to avoid the extra cost of reserving a room within the block at the host hotel. Some attendees reserve rooms outside the host hotel—the ROHH strategy. Others reserve rooms outside the block—the ROB strategy.

    Conference sponsors have succeeded in countering these strategies by increasing the conference registration fee by a fixed amount and then offering an equivalent registration fee discount to attendees who book rooms in the block. A study has shown that if this registration discount is equal to at least half the potential savings of an attendee's particular cost-saving strategy, the attendee is much more likely to reserve a room within the block.

Weekend Conferences

    Ten conferences are scheduled for the same weekend in City X. For each conference, the table lists the conference sponsor, the registration fee, the discounted registration fee (if any), the host hotel, the rate for rooms in the block at the host hotel, and the lowest rate for an available room in the host hotel during that same weekend. Conference attendees will require two nights lodging, and all room rates are per guest, per night, assuming two guests per room. The lowest rate for an available room in City X on this same weekend is S65.