Download Ecosystem-based management

Role of mesopelagic fishes in
the marine ecosystem
Forage fish are an important link in the
ecosystem
Forage fish are small fish that transfer energy from zooplankton
to large predators
MESOPELAGIC FISH ARE FORAGE
FISH TOO!
Predators
Prey
Beamish et al. 1999
What will happen if populations of mesopelagic
fishes decline?
What will happen if populations of mesopelagic
fishes decline?
It could cause declines of seabirds, tunas and sharks,
and dolphins (because they don’t have enough food).
Could increase populations of zooplankton (because it
would decrease predation on them).
What could cause mesopelagic fish
populations to decline?
What could cause mesopelagic fish
populations to decline?
● eating microplastic
● climate change, acidification, decreasing oxygen
levels
● pollution
● oil spills
● fishing
Plastics found in
mesopelagic fish
Fisheries management
Limit fishery harvests by government
agencies
Traditionally, each species was managed completed
separately from each other
Ecosystem-based Management
Place-based approach to natural resource use that
aims to restore and protect the health, function
and resilience of entire ecosystems for the benefit
of all organisms
Ecosystem-based Management
Takes into account the environment, the food web,
and human interests (e.g., fishing, conservation)
Example of Ecosystem-Based Management
In 2013, sea lion pups were
found stranding on beaches.
They were starving.
Example of Ecosystem-Based Management
It turns out there was not
enough of their favorite food,
the forage fish sardines
Example of Ecosystem-Based Management
It turns out there was not
enough of their favorite food,
the forage fish sardines
Response: Managers decreased the amount of sardines
that fishermen can take, so the population could recover
Conclusions
● Forage fish are a key link in marine ecosystems
● Mesopelagic fish are forage fish that are
threatened by human activities
● Ecosystem-based management aims to restore
and protect the health, function and resilience of
entire ecosystems for the benefit of the environment
and humans
Assignment
● You will become a fisheries manager
● Scenarios are presented, and you have to make
decisions to make sure that the health of the
ecosystem and fisherman’s interests are wellbalanced