Transcript No Slide Title - FTP-UNU

Coastal Fisheries Policy and Planning Course, 28/01/08 – 8/02/08, Apia, Samoa
An ecosystem approach
to coastal fisheries
in Pacific island countries
by
Michael King
Based on a presentation given at
the HOF meeting in Noumea, 2007
Secretariat of the Pacific Community
Starting from a basic system, a fishery is …
A fish stock with an input of fishing effort
and an output of catch
Conventional fisheries management …
Controls on amount of fishing (eg licences)
and quantity of fish caught (eg quotas)
However, a fishery is part of an ecosystem …
The ecosystem will be affected by
both fisheries and non-fisheries impacts.
an Ecosystem Approach to Fisheries (EAF) …
Controls to protect ecosystems added to usual controls on
amount of fishing and quantity of fish caught
Both fishing activities and
non-fishing activities affect ecosystems
EAF is usually concerned with impacts of fishing activities.
However, many HOFs believe that non-fisheries activities
(eg sewage disposal, coastal development)
result in more harmful impacts on coastal ecosystems
Hard to distinguish between effects of overfishing and
environmental impacts on stock sizes.
No theories and models to help.
What are the effects of negative impacts
on ecosystems?
Useful here to look at the factors
that regulate populations including fish stocks
The regulation of populations …
Stock growth and biomass …
Effects of impacts on ecosystem …
The objective of EAF is the
sustainable use of marine ecosystems
… and management that provides for present needs
while allowing for the needs of future generations.
In Pacific Islands, high rates of population increase
means this should be of great concern.
Rates of about 4% pa in some islands
will result in populations doubling
in less than 19 years!
What are the key issues in EAF?
These relate to …
target species – overfishing
non-target species
ecosystem issues
(including non-retained species)
environmental issues
fishing communities & society
Look at these issues in detail…
Target species – overfishing
… in which recruitment cannot replace numbers lost.
.. but there may be an over-concern with estimating stock parameters
Stock assessment/yield curves usually done
to estimate optimum catches and fishing effort
However, yield curves …
1. often require more data than are available
2. may result in optimistic estimates of yield/effort
3. are less useful in multispecies fisheries
Yield curves can be drawn with minimal inputs –
eg unexploited biomass & population growth rate, r
Yield curves are less useful in multispecies fisheries
(less abundant species may be overfished at overall fmey)
One notable exception is a multispecies
curve based on AREA rather than TIME
Each point on graph represents mean catch per area for different villages
(with fishing grounds that are similar ecologically)
If 15 people per hectare represents the optimum fishing effort,
many village fishing grounds are overexploited
But, even if optimum effort & yield can be
estimated, how can it be used?
In many coastal (particularly subsistence) fisheries,
it is difficult to control both …
► the
amount of fishing done, and
► the quantity of fish caught
ALSO – an EAF precautionary approach suggests that
the conservation of fish stocks must be given priority
over the optimisation of fish catches.
Conventional controls are used in the
absence of assessment – examples …
Input controls on fishing … eg
size limits – widely used (even if poorly enforced)
gear controls – eg banning of SCUBA to catch lobsters
Output controls on fish caught … eg
quotas – quota on trochus in Cook Islands set
at 30-40% of stock (between 80 and 110 mm).
this is good example of “safe” precautionary limits
applied in the absence
of formal stock assessment
Non-target species are a world concern
(here discards are given as % of total catch; from FAO)
However, no trawls or dredges in PICs (except for prawns in PNG)
and tuna longlining – not relevant to coastal fisheries
However, some issues with
fish fences and loosely-hung gill nets which
are unselective (and “ghost fish” when abandoned).
In some PICs, restrictions on number and mesh sizes
Ecosystem issues include direct impacts
by damaging fishing methods (inc. dynamite & poisons).
We must accept that
traditional fishing methods can also cause damage
Gleaning on reef flats
Communal fish drives across reefs
Breaking of coral to catch small fish
Use of plant-derived fish poisons
In the past, these methods caused less damage
ONLY
because fewer people were involved.
Global concern over selective removal of species
that disrupt ecosystems (by affecting predators & prey)
Commercial fisheries
often target species
from one trophic level.
However,
artisanal fishers
target species
from many
different
trophic levels.
and this may be
less disruptive
to ecosystems.
But – there is no doubt that the removal of some
species will affect coral reef ecosystems.
2 examples from the literature - the removal of ….
► Parrotfishes will
allow algae to grow and smother corals.
► Triggerfishes etc will allows urchin populations
to increase and erode corals faster than they can grow.
Environmental issues
Many non-fisheries activities have the potential to impact
marine ecosystems and fisheries.
Which ones are important in Pacific islands?
Environmental impacts in PICs
from questionnaires … 0%=no effect; 50%=moderate; 100%=severe
0
5
10
15
20
25
30
35
40
45
50
55
60
65
70
Over-fishing of inshore marine species
Sewage, nutrients entering coastal waters
Pollutants, oil, entering the sea from industry
Pollutants, including oil, from boats
Pollutants, fertilizers, from agriculture
Garbage dumps at the edge of the sea
Reclamation of land; loss of marine habitats
Excessive coastal development; hotels, etc
Silt entering coastal waters/lagoons
Loss of beaches through sand mining
Loss of corals - cement, buildings etc
Loss of corals - people on reef (gleaning etc)
Loss of corals through coral bleaching
Destructive fishing methods (dynamite etc)
Presence of alien and invasive species
Siltation, garbage dumps, nutrients result in major impacts …
75
Siltation in coastal waters
Sources - forestry, land-clearing, development, mining?
Results - smothered corals; decreasing depths in lagoons
Excessive nutrients in coastal waters
Sources - human & stock sewage, fertilizers?
Results - eutrophic conditions (high bacteria/low O2)
Eutrophic conditions are associated with
- fish kills (caused by low O2 ), excessive plant growth;
► corals in lagoons replaced by seagrasses
► abrasion of corals (eg by Sargassum).
Excessive nutrients result in high abundance of
dinoflagellates and harmful algal blooms (HABs)
including those responsible for ciguatera.
Toxins produced by some dinoflagellates (eg Karenia spp) produce
airbourne toxins causing asthma-like symptoms in people - eg Cook Islands.
47% of all countries reported some increase in HABs
Key points are that …
►Many of the environmental issues
that impact coastal ecosystems
(forestry, development, sewage systems etc)
are beyond the control
of government fisheries agencies.
AND
► Controls on fishing and ecosystems
are difficult to apply (and especially enforce)
in rural fishing communities.
There is, therefore, a need to extend the
management base for EAF to include …
► Fishing communities that have …
Vested interest in sustainable seafood stocks
Knowledge of threats & solutions
Traditional control (often) of adjacent coastlines.
► Other
government agencies that have …
Responsibility for many non-fisheries activities
that affect marine ecosystems.
Many communities and non-fisheries agencies are
already contributing to solutions in EAF issues …
Example of community input
Problem – Availability of cheap underwater torches
allowed spearing of sleeping fish at night
Result - large breeding fish removed
- devastated fish stocks
Solution - method banned by some villages under CBFM
Example of environmental agency input into EAF
Problem – Uncontrolled coastal development
Result – Increase in silt; loss of fish habitats
Solution – Environmental impact assessments (EIAs)
required before each new project or development
- must include government projects – main offenders?
(eg habitat loss - over 25% of wetlands in Tutuila in A.Samoa)
How can the management base be extended?
Perhaps management advisory committees (?)
with members from …
Fishing communities?
Environmental agencies?
Other relevant government agencies?
NGOs with environmental interests?
SPC is working in this area –
commendable example in Marshall Islands …
fisheries are managed by representatives from
fisheries, environment, education etc
A consultative process is needed to identify
and give priority to important issues
- score 1(minor impact) to 4 (extreme impact) in columns 2 and 3)
Issue
Consequence Consequence Total impact
to local area to entire
(column 2
ecosystem
times col.3)
Rubbish
dumps near
coast
4
2
8
Siltation of
lagoons
etc.
2
3
6
For each priority issue - set objectives,
targets and propose management actions
Objective
Target and Indicator
limit
Management
actions
To maintain
the spawning
stock at level
at which the
risk of stock
collapse is
minimised.
Target –
Density from
11 fish per underwater visual
100 m2
census surveys
Limit –
6 fish per
100 m2
a) Enforce
size limits
b) Reduce
fishing effort
c) Impose
closed
seasons
The indicator (abundance of mature individuals)
can be plotted over time.
Example - indicator drops below limit in year 7
and triggers strong management actions
– eg reduce fishing effort, closed seasons etc
EAF objectives can be also be devised for
ecological, economic and social issues.
One objective covering both
biological and ecosystem issues
relates to
protecting some part of an entire ecosystem
from exploitation.
Marine Protected Areas (MPAs)
are widely used to address this objective.
MPAs are a moderate to very high priority
in 86% of all countries surveyed.
MPAs may protect stocks from the effects
of environmental fluctuations.
► fluctuations may
cause an exploited stock to crash
- to drop below the number required to successfully reproduce (Allee effect)
►a
pool of individuals in an MPA may avoid this
In MPAs larvae settle within its boundaries (self
recruitment) or disperse within an envelope.
Juveniles and adults may “spillover” from MPA.
In conclusion …
► The view
of fisheries managers is that non-fisheries
activities are affecting ecosystems and fish stocks.
► Many
countries regard communities as
key stakeholders (many have implemented CBFM
with SPC assistance).
To implement EAF, this emphasises the need to involve …
relevant government Agencies
► fishing communities
►
* Much work is being done by SPC to involve both.
* Also, a regional meeting was proposed (in 2003) to involve
representatives from environment as well as fisheries agencies.
Exercise on EAF based on figure below.
- break into 4 groups (Advisory panels)
to do this exercise)
1) Possible causes of environmental degradation
Examine illustration and list issues and possible causes
(Siltation and eutrophication are priority issues)
2) How could impacts be reduced and controlled?
Propose actions/controls that would reduce impacts
on marine ecosystems
3. How could effects be assessed?
set objectives – the expected result
targets & limits – desirable & undesirable positions
indicators – a measurable indication of performance
Objective
(example)
Target and Indicator
limit
To reduce
levels of TBT
in sea to a
level that does
not affect
marine life.
Target –
6? ppm
Limit –
11? ppm
Concentration of
TBT in sea water.
Management
actions
Effects of actions could be monitored
based on the use of indicators and reference levels.
4. Additional management actions
list management actions in increasing order of severity
Objective
(example)
Target and Indicator
limit
To reduce
levels of TBT
in sea to a
level that does
not affect
marine life.
Target –
6? ppm
Limit –
11? ppm
Management
actions
Concentration of a) Ban use of
TBT in sea water. TBT on local
boats
b) Ban foreign
vessels using
TBT
In example …
Year 0 - local use of TBT banned
Year 4 – entry of foreign vessels using TBT banned