When Marine mammals Migrate they have there are multiple factors

• Molting

  • Phocids - annual molt

  • Cetaceans

• Avoidance

  • Predators / Disease

  • Thermoregulation - area does not meet there temp needs

  • Whales that undergo migration do NOT eat

    • this is a time to dump the parasite loads

  • Arabian sea whales (they are the exception)

    • Have the highest parasite lead ie by not migrating

• Thermoregulation

  • Calfs

    • calf can die because of high metabolism

    • low blubber to regulate

  • Manatee

    • go to springs during winter (Warm and stable)

Movements: spatial and temporal variation

• Diurnal and tidal

  • Hawaiian spinner dolphins have a daily schedule (slide 7)

    • Sleep during day (when human activity is highest). Rest close to shore (sandy bottom shallow bay)

    • Forage at night due to deep scattering layer

  • Humpback dolphins

    • Move in response to the incoming tide

      • Able to forage in/around mangroves at higher tide

    • Move back to the ocean with reduced tide

• Seasonal

  • Humpback whales

    • Feeding grounds in summer and breeding grounds in winter

  • Arabian sea humpback whales - the only known humpback whale population that does not have seasonal migrations

    • Water is very nutrient-dense all year round

      • near the equator, but global currents produce upwellings that provide lots of nutrients

    • Isolated for ~70,000 years

    • Critically endangered (less than 150)

      • Lots of anthropogenic threats (shipping, development)

• Scale of Movements

  • Slide 5 diagram

  • Movement is costly

  • Only move to meet certain needs

  • Movement happens at different special and temporal scales

  • Home range - all of the areas that meets the daily needs of the individual (eating, breeding)

  • Utilization distribution - mathematical equation of probability. What is the probability that an animal will be in this location. If the individual has a 95% probability then that is the typical home range

  • Core areas - preferred location in the home range.

    • 50% probability that the animal is in that spot (ex: feeding ground)

  • Migration - repeated large-scale movement between 2 areas in the animals home range

  • Dispersal - one-time permanent movement. Leaving home range.

    • Often sex-specific dispersal (EX: inbreeding avoidance)

Why assess home range?

• Compare among animals (ex: reproductive state, age, sex)

  • Humpback whale example/map with dots (slide 6) - Mom and calves are closer to the shore than single whales.

• Changes by season

  • The intersection of Intracoastal and SJR is a hotspot for foraging year-round

• Identify critical areas for management

Population structure

• Population

  • group of interbreeding individuals of the same species

• How do you define boundaries?

  • Biological

    • Measurable and meaningful to animal

      • genetic

  • Political

    • State bound, country

    • Human set

  • Practical

    • You can keep track of the conservation of self

    • set small to keep tabs

Population size - Why count?

• Abundance

• Trends

  • is it stable?

  • If decline is conservation

• Life History Characteristics

  • indirect but released to abundance, grow, reproduction

    • If one dies needs to be replaced

    • Right Whale: has an annual birth

    • Pacific Whale: Gap year

• Management Success

  • How many count

• Example:

  • Spinner dolphins trying to sleep management (9am - 3pm)

Methods for Determining Abundance

• Census

  • A complete count of individuals

  • What are the assumptions?

    • Animals don’t fill out paperwork

    • Their moving in water

  • Make it easy for some species: The arrival survey gets a grid for counting

• Index count

  • Count sample- Trends only

  • Limited can’t extrapolate the whole

• Estimates

  • The count sample extrapolates the population

    • Link transects (Distance sampling)

      • survey large area

      • Transect line systematically placed

      • Count # animals and spatial arrangement around the line

    • Mark recapture

Line transect Assumptions

• Sample represents population

  • can be done wrong

• Assumptions

  • no missed animals

  • need to be at a specific pace to reduce missed animals

  • animals do not move prior to detection

  • Data recorded accurately

  • observations independent

Studying marine mammal movement (two types)

• (type 1) Indirect: inferred from distribution

  • EX: Humpback whale distribution in winter vs summer.

• (type 2) Direct: repeated observations of individuals

  • Repeated observation of individuals

  • Tags and branding

  • Natural markings (Different types)

    • Manatees - scars

    • Humpback whale - fluke pigmentation

    • Sperm whales - fluke serrations/notches

    • Right whale - callosities

    • Orca - saddle patch

    • Bottlenose dolphins - dorsal fin shape and notches

    • Grey seal - fur pattern in females is distinctive

  • Genetic tagging

  • Telemetry (very costly)

    • Devices

      • Pinnipeds - glue onto fur

      • Polar bears - collar

      • Manatees - tether devise using a rope to fluke

      • Dolphins - bolt through dorsal fin (very invasive)