L8 - Threats to whales Flashcards
(34 cards)
what are the 6 threats to whales mentioned in class?
- Loss of habitat
- Overfishing
- Pollution
- Underwater noise
- Ship strikes
- Entanglement
what is wrong with Whale population ecology?
Difficult to observe to get estimates
How do we get whale population estimate samples
-often use multiple sound sensors to triangulate whale calls
- find them on continental shelves
what is wrong with whale population ecology
- Large margin of error
- all estimates will be inaccurate
what do current whale population ecology estimates show?
low populations with VERY slow recovery
when was the moratorium on whaling
1986
what is the period between 1925 and 1960 also known as?
the “Whaling Olympics”
what is Live capture?
capturing whales alive for the use of display or tagging
what whales where targeted for live capture?
Orcas
what is dangerous about live capture?
many whales either died from fear and heart attack when captured in nets or from entanglement
Does Live Capture of whales still occur?
banned in many places
- still can get a permit in BC
what whale is most commonly caught for captivity?
Beluga Whales
what is “the Blob”
- a large mass of super productive algae
- dense algae bloom that die all at once
- creates dead zones by blocking out light and taking up nutrients.
- 2013
why do coastal regions become so degraded
High population densities and Cities in coastal or river regions.
- More people = more pollution
Are whales K selective or R selective?
K selective and requires stable ecosystems
- density independent
- limited breeding
- capital breeders
what is Dredging
the processes of making a water basin deeper to support bigger ships
why is dredging bad?
- water turbidity
- Noise pollution
- disturbance
- pollution
What are Some Mitigation strategies for whale conservation?
- protection acts
- work windows
- Marine Mammal observation (MMO)
- Exclusion Zones
what is By-catch
fisherman accidentally catching something that is not the targeted species.
this can be other fish, or marine mammels.
what are some problems with Bi-catch
- difficult to police
- Bi-catch is often wasted
when was the ban on drift net fisheries and why
1992
- catch everything in a given area. very wasteful practice
-Mammals, Birds, Fish
What is a ghost net?
a free floating fishing net that has been left behind by people.
Fills with fish –> fish Die and the net sinks to ocean floor –> Animals Rot away –> net rises to catch more fish
endless cycle.
what is entanglement
when whales get caught in fishing nets, and movement is restricted
what are fishing nets required to include now?
owner information, so charges can be placed if lost or damaged.
