Transcript Management Framework in the Pacific for Highly Migratory

SIO 296: January 15, 2010
Highly Migratory Species:
Research and Management
SWFSC HMS Biology and Population
Dynamics Group
Antonella Preti
Owyn Snodgrass
Heidi Dewar
James Wraith
Steve Teo
John Hyde
John Childers
Stephanie Snyder
Natalie Spear
Candan Soykan
Russ Vetter
Amber Michaud
Lecture Outline
• Management Framework in the Pacific for
Highly Migratory Large Pelagic Fish (Tuna and
Tuna-like Species)
• Bycatch Issues
• Stock Structure
• Ecosystem Considerations
• Foraging Ecology Lab/Dissection
International Management
• IATTC: Advised by their scientific staff with
input from scientists and delegates of member
nations
• WCPFC: Advised for the North Pacific by
working groups of the International Scientific
Committee (ISC) made up of scientists from
member nations
Transboundary Large Pelagic Fish
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Albacore (Thunnus alalunga)
Bluefin Tuna (T. orientalis)
Yellowfin Tuna (T. albacares)
Bigeye Tuna (T. obesus)
Skipjack (Katsuwonus pelamis)
Dorado (Coryphaena hippurus)
Swordfish (Xiphias gladius)
Striped Marlin (Tetrapturus audax)
Shortfin Mako Shark (Isurus oxyrinchus)
Thresher Sharks (Alopias spp.)
Blue Shark (Prionace glauca)
Domestic Management
• Regional Fishery Management Councils: PFMC,
WPFMC
– HMS Management Plan since 2004
– Advised by: a management team made up of State and Federal
representatives including scientists (HMSMT); a scientific and
statistical committee (SSC); a subpanel of constituents from the
commercial and recreational fisheries industries and NGOs (HMSAS);
the public
• State Agencies: CA, OR, WA
– Advised by their staff with input from constituent groups and the
public
Bycatch
The issue…
• Fisheries for tuna and other highly migratory
species are often constrained by the incidental
take of vulnerable non-target species. Even
fisheries that target productive, healthy stocks
can face restrictions if interactions with
protected species occur.
Examples for HMS in the Pacific include 1) the closure of coastal CA waters to
drift gillnet gear out to 75 miles during the spring to protect reproductive
female thresher sharks, and 2) the 2001-2004 closure of the Hawaii
shallow-set longline fishery in the North Pacific due to turtle interactions.
Bycatch
• The species
– Mammals, turtles, birds,
sharks, vulnerable life
stages of target fish, other
fish
Bycatch
• Conservation measures:
Sharks, sea turtles, seabirds, juvenile fish
IATTC
(see www.iattc.org/ResolutionsActiveENG.htm)
WCPFC
(see www.wcpfc.int/conservation-and-management-measures)
Bycatch quantification: observer programs,
logbooks, landings receipts
Catch of the major finfish species for all observed DGN sets 1990
through Jan 2008. Number of sets is 7891.
Catch of the major finfish species for all observed CA-based SSLL sets,
October 2001 through February 2004. Number of sets is 469.
Total
Observed
Catch
Catch per
100
Swordfish
Catch of
Swordfish
per 100
Finfish
Total
Observed
Catch
Catch per
100
Swordfish
Catch of
Swordfish
per 100
Finfish
Mola, Common
49,691
298.5
33
Shark, Blue
5,575
74.2
135
Shark, Blue
21,692
130.3
77
Albacore
460
6.1
1,633
Albacore
16,564
99.5
100
Shark, Shortfin Mako
249
3.3
3,017
Tuna, Skipjack
9,550
57.4
174
Longnose Lancetfish
235
3.1
3,197
Shark, Shortfin Mako
7,183
43.2
232
Tuna, Bigeye
223
3.0
3,369
Mackerel, Pacific
6,210
37.3
268
Escolar
194
2.6
3,872
Shark, Common
Thresher
5,945
35.7
280
Stingray, Pelagic
125
1.7
6,010
Opah
4,548
27.3
366
Oilfish
86
1.1
8,735
Tuna, Bluefin
3,744
22.5
445
Dorado
65
0.9
11,557
Mackerel, Bullet
3,020
18.1
551
Mola, Common
51
0.7
14,729
All Others
5,093
30.6
327
All Others
258
3.4
2,912
Swordfish, Broadbill
16,646
Species
Species
Swordfish, Broadbill
7,512
Data suggest that longline gear catches fewer non-target
fish for each swordfish caught.
Gear Modifications
• Using corrodible links
to reduce trailing tackle
on thresher sharks
• Testing rare earth
metals to deter sharks
• Using circle hooks to
prevent swallowing and
esophogeal damage
Preliminary results from Wang,
Swimmer and Hutchinson, PIFSC
TurtleWatch – predicting turtle
distribution from SST
Based on two decades of loggerhead turtle satellite tracking and fishery effort data.
See Howell et al., Endangered Species Research, 2008.
Stock Structure
The issue…
Are there discrete populations that should be parameterized
separately in the stock assessments and managed separately?
Do individual fisheries exploit a single or multiple sub-stocks?
Tools for Examining Stock Structure
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Tagging
Genetics
Parasites
Morphology/life history
Fishery dynamics
Otolith Microchemistry
Albacore movements, mixing and stock structure:
20 fish, 5 migratory patterns
Trans-Pacific
(n=1)
North-CentralNorth (n=5)
North-CentralSouth (n=3)
South-CentralSouth (n=4)
Overwinter
Baja (n=7)
Genetics: RFLP, mtDNA, microsatellites
Chile I
Chile II
Relative frequencies of mitochondrial haplotypes found for shortfin makos
throughout the Pacific. Significant differences were found between north and
south Pacific populations.
Stock Structure
• Otolith Microchemistry
Used as a technique to differentiate stocks and reconstruct the
migratory history of individual fish. Otoliths precipitate with
growth and elements are integrated into the aragonite protein
matrix. Otoliths are metabolically inert; resorption or
remobilization of newly deposited elements is negligible. The
chemical composition of otoliths (e.g. SR:Ca ratios and others)
serve as natural tags or chemical signatures that reflect the
chemical composition of the individual’s habitats over time.
Stock Structure
• Parasites
• Morphology/life
history
– Growth rates
– Skin morphology
– Fishery dynamics
“wrinkle belly” swordfish
with cookie cutter shark bite
From Laurs and Wetherall, 1981
Ecosystem Considerations
• Spatial and Temporal variation in behavior and
distribution
• Oceanographic influences
• Multi-species associations
• Foraging Ecology
Site Specific Behavior
Interannual
Variations
Movements of CA sea lions tagged in
2003 and 2004. From Weise et al. 2006
2003
2004
FACTOR(2)
Thresher
Blue
an
ch
sa o vy
m rdi
ac n e
ke
ja
re
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l
m
ac
ke
r
sa el
sc roc ury
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cu ae
din
m as
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m t
fre
m
a
t
r
G arg ke
on o t
a t na sq
us ut uid
fl o
sp sq
we
rv ju p. ui d
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e b u
Hi jew o sq i d
st e u
io ll id
oc t eu squ
to th i i d
gi p us s sp
an s .
t o qu
ct id
op
so
us
up
f in
sh
re
la
ar
gi
k
cr
ed
cr
ab
Mako
Geometric Index of Importance
(GII) for prey greater than 5.0
Niche partitioning among
co-occurring species
70
60
50
40
Shortfin Mako
Blue Shark
Common Thresher
Coastal
Pelagics
30
Cephalopods
20
Other Teleosts
10
0
5
SPECIES
-4
-4
Blue
Mako
Thresher
2
-1
-1
2
FACTOR(1)
5
Wrap up: based on our concluding discussions
• We should consider adaptive management strategies
due to spatial and temporal variation in the behavior
in target and bycatch species
• We should strive for predictive models that will help
to forecast fluctuations in availabilty in order to
establish effective harvest guidelines
• Closing fisheries is not always the best way to
mitigate bycatch: e.g. transfer effect
Excercise
• Compare diets of two predators, A and B, collected by observers in the CA
drift gillnet fishery
– Calculate %Number, %Weight, %Frequency of Occurrence (%FO),
Geometric Index of Importance (GII) and Index of Relative Importance
(IRI) for each prey to determine its contributions to the diet of each
predator
– Calculate the Schoener’s Index of dietary overlap for the 2 predators
– If I told you these were 2 different predators collected in overlapping
time and space, what conclusions would you draw?
– If I told you this is one predator but sampled in two different years, fall
1998 and fall 1999, what conclusions would you draw?
Exercise cont., formulas
%Ni = (Number of preyi)/(Total Number of all prey)*100
%Wi = (Weight of preyi)/Total Weight of all prey)*100
%FOi = (Number of stomachs containing preyi)/
Total Number of stomachs containing any prey)*100
GIIi = (%Ni+ %Wi +%FOi)/ 3
IRIi = (%Ni + %Wi) * %FOi
Schoener’s Index = CAB = 1 – 0.5(Σ │%NiA /100- %NiB/100 │)