MARB 403 Lecture 5
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remember to ask about right whale story tomorrow (something to do with right whales and mating... 
)
Baleen Whale Feeding
4 types of baleen whales
- Rorquals - lunge feeding
- Right & bowhead whales - skim feeding
- Gray whale - suction feeding
- Pygmy Right Whale - similar to right whales and rorquals
Recall Rorqual is Norwegian for "Tube whale", referring to the throat grooves
Baleen whales eat krill:
- Calanus (copepod) is smallest; eaten by right, sei, and young fin whales
- Thysanoessa (euphausiid)
Basic summaries of baleen whale diets
Most whales also feed on fish and squid, except the following:
- of the rorquals, the blue whale is the only one that does not eat fish
- The balaenids only eat crustaceans (too slow for fish)
- Gray Whale, since it sucks
Rorquals seem to be doing very well, but lunge feeding requires a lot of energy: do they get enough food to offset that expenditure?
Food is found south of Antarctic convergence (and near antarctic itself
During the 40's, whales were doing fine because of the war. After the war, whaling became more popular.
- Northeast sea between North America and Greenland: Labrador & Gulf shear
- Above Norway and Sweden: Greenland current
- Patches of far-North Pacific: Kuroshio Current, Bering Sea Drift
- California coastline (!): California current
- West coast of South America: Peru current
- Antarctic convergence: Circum-Antarctic Drift, West Wind Drift
- East of South African tip: Benguela current
- South of New Zealand?
Gray Whales
Suck silt from bottom
- Never stop eating
- very messy eaters: they bring a lot of nutrients to surface
- Often seen with whale lice (cyamids) and barnacles
Right Whales
- Almost always have barnacles
Bowhead Whales
Similar in shape to Right Whales
Blowhole behind high "stack" used to break ice
Most pagophilic [1] of whales
When food is really close to surface, whales will skim on their sides to maximize food intake
"V"-shaped formation for feeding: echelon (not used often)
- Right whales use it as well.
May also bring up bottom-silt
Rorquals
Minke whales have uneven coloration: right side is lighter in color, left is black
2-animal echelon
Blue whales are highly streamlined for their size
Overlunging helps empty the distended throat
Humpback whales use bubbles to herd fish together
- Lot of coordination
- simultaneous lunging by several individuals
Foraging Dives of Fin Whales: Are they Time- or Energy-maximizers?
Authors:
- Acevedo-Gutiérrez
- Don A. Croll
- Karen Newton
- Bernie R. Tershy
- Jorje Urbán Ramírez
Proportion of foraging time: will they choose shallowest possible dive?
Energetic gain: do they dive deep if prey availability increases with depth?
Density of Krill found using echosounders (depth sounders)
- Krill concentratinon is higher at depth during the day.
- At night, some krill come to the surface (more uniform distribution)
Prediction:
- Forage at night if maximizing foraging time
- Forage during day if maximizing energy gain
Foraging dive profile: repeated lunges (gulps) from at depth
The researchers found that krill aggregations form more often during day, and foraging dive frequency follows a very similar pattern
Most foraging happens during the day at depth when krill aggregations are more abundant
- support hypothesis that they maximize energetic gain
Scientists of the Day
Roger Payne. Ocean Alliance (conservation group)
- IWC Whaling moratorium
- 1971 paper describing low-frequency sounds in baleen whales and approximated loudness
- In pre-industrial oceans, sounds could travel across oceans
- His hypotheses have been proven
Katy Payne. Cornell Univ.
- Discovered and documented humpback whale songs
- Very musical background, so it seems fitting...
- Good artist; sensed vibrations in feet while drawing elephants; first to record infrasound in elephants
Check out MARMAM communications
Footnotes
- ↑ pagophilic: Ice-loving