Chapter 7: Patterns of movement

Distribution patterns

➢ Information from hunting records, survey ships, strandings

➢ From passive acoustics, e.g. Tracking of single blue whale 3000km across mid Atlantic

➢ Population characteristics, e.g. Parasite infections, morphological features, genetic markers, coloration,

and diet components (stomach, fatty acids...)

Movement of individuals

➢Branding or discovery markings

➢ID through natural markings:

shows migration patterns site fidelity to feeding / breeding groundschanges in feeding distribution

➢Photo-ID method

➢Genetic tagging: tissue samples / DNA to identify individuals, resampling, sex determination. But sampling is usually invasive and can disturb behaviour/movement of animals!

➢Non-invasive: faeces samples («Tucker» - 400m away) Distinguishing the Impacts of Inadequate Prey and Vessel Traffic on an Endangered Killer Whale (Orcinus orca) Population

➢Telemetry (D-tags, satellite tags, neck collars..) but invasive!

Foraging

➢Areas of high productivity - banks, canyons edge of continental shelf, slopes, transient oceanographic features mesoscale frontal systems or polar fronts

➢Re-sightings of individuals in specific feeding areas ➢Preference for specific prey

e.g. Orcas in Canada: transients and residents groups

Size, gender and reproduction

➢Harbour seals - foraging range positively correlates with body size - greater in males than females

➢Migration differences between males and females: Sperm whales, Belugas and Elephant seal ➢Female otariids nurse pups several months & are restricted to breeding grounds

(but may travel 900km to feed)

Tidal/diurnal factors

➢Some dolphins swim with dial cycle from open water to coastal areas due to prey movement

➢Often prey moves to surface in evening, e.g. Herring / Killer whales, Squid / Pilot whales

➢Seals need tidal areas for haul out sites: rest during low tide when rocks are out of the water and hunt when

high tide

Seasonal movements

➢Cycles of reproduction & feeding, feeding areas can change due to prey abundance!

Example: Herring changed overwintering grounds from Tysfjord to the north of Tromso!

➢Site fidelity to breeding areas high for Pinnipeds: need to haul out for birth and nursing / mating follows / fasting during breeding. Breeding and feeding sites often far away, e.g. Elephant seals

➢Humpback, Grey & Right whales travel to specific breeding sites, far away from feeding sites

➢For many other species breeding and feeding areas are close

Moult

Specific haul out areas, e.g. elephant seals 1000km away from feeding grounds

➢Beluga whales - fresh water river mouths for moult

➢Hooded seals swim > 1000km from moult to haul out

places in 47 days!

Pinnipeds - fault out

➢Need to spend a lot of time on haul out areas on landca. 40% of their time, away from feeding / breeding areas

➢Thermal regulation, predator avoidance, rest (reduced metabolic rate), social interaction and parasite reduction

➢Short forage trips 2-5 days from haul out place

➢Elephant seals don't haul out during foraging, rest in water

Thermoregulation manatees

Warms up in warmer areas, e.g. power plants or just warmer water areas

Migration - routes

Winter & Summer grounds, normally north-south (polar - equatorial) migration

-> Philopatry feeding grounds 90% (Humpback whales) - learned through maternal association in first year!

Example Humpback whale migration from Norway to Caribbean through Photo-ID

Distance

➢Long travel (round trips 15.-25.000 km Grey whales, 18.600 km Humpback whales, 6.000 km Elephant seals)

➢Short or no travel (Humpback whales in Indian Ocean or Arabian Sea, breeding female Sperm whales, Bryde whales and Omura whales in tropics)

Individual travel / cross ocean transects

Humpback Whales: Japan to British Columbia, Canada Male Humpback Whale sets new record with 13,000km Journey from South America to Africa!

Long distance travel

Killer Whales for epidermal moulting:

Antarctica - Brazil (10.000km) (Pitman et al., 2019)

Alaska – Azores (5.400-km with top speed of 252km a day

Intraspecific differences

(age, sex or reproductive stage)

➢Sexual dimorphism - longer feeding migrations for males

Sperm whales (Azores - Arctic)

Walruses (Svalbard -Franz Josef Land)

Belugas (Canada)

Elephant seals (continental shelf)

But: northern Right Whales only females with calves migrate south!

➢Individuals: Juveniles may take different migration routes

some individuals stay in feeding grounds and do not migrate every year! e.g. older male sperm whales in northern Norway

➢Females with calves arrive last in feeding grounds but migrate first to breeding grounds

Exploration routes

➢Phocid seals: weaned pups must explore environment e.g. Harp seals pups,or hooded seals with long migration routes

➢Necessary to find new food patches!

➢But also adult individuals explore

Orientation

Orientation (recognizing and maintaining direction)

Navigation (identifying the direction of a given point in space)

➢Underwater & land topography: sight & hearing e.g. seals often use land marks, association with seabed topography

But: Gray whales use direct path, not topography

Navigation

➢Sun & stars: harbour seals can use the star sky to navigate!

➢Currents / other oceanographic features such as water masses, currents, frontal systems, temperature, salinity, turbidity etc.

➢Geomagnetism: passive electrolocation has been demonstrated in the Guiana dolphin and Bottlenose dolphins - may detect Earths magnetic field for large-scale orientation

➢Polarized light? Not proven

Strandings and anthropogenic impacts

➢Wrong navigation?

➢Sand banks

➢Starvation & Illness (e.g. Pilot Whales in New Zealand/Australia)

➢Ocean Noise Pollution

➢Seismic exploration

➢Military Sonar ➢Disease / Parasites ➢Sunspot activities ➢Unknown causes ...

Antropogenic impacts

-> Too much Garbage, Fishing gear - Bycatch & Entanglements, Chemical & Plastic Pollution Oil & Gas extraction, Transport, Recreation & Tourism

-> Aquaculture, Military actions ...

-> Climate change!