Pelagic Predators Food Habits Project

1
Pelagic Predators Food Habits Project
2
Our Vision

• Create a forum for moderated exchange of valuable
  feeding habits data
• Archive historical data for continued use into
  the future

3
Why are these data so valuable?
Understanding trophic relationships is an
integral component of ecosystem-based
management Movement from single-species to
multi-species assessment requires good knowledge
of trophic linkages Feeding habits reflect food
web status (animals as sampling devices) Long
time series reveal regime shifts and other
changes in ecosystem
5
Toothed Whales
Lamnids
Blue Marlin
Other Billfish
Swordfish
Carcharhinids
Blue Shark
4
Yellowfin
Albacore
Bigeye
Mahi mahi
Skipjack
Large Squid
Small scombrids
Baleen Whales
Trophic Level
3
Small Squid
Mesopelagic Fish
Epipelagic Fish
2
4
Using a Food Habits Database

• Our hypothesis
• Reduced abundance of large pelagic predators may
  gave enhanced the productivity of economically
  important tunas
• If true then
• Tunas should comprise a significant component of
  pelagic predator diets, throughout the range of
  their populations

No single sampling program can possibly address
this question
5
Towards a Food Habits Database

• We presently have a database containing
  summarized data from 29 peer-reviewed
  publications
• Predators ( studies)
• Tunas Yellowfin (10) Skipjack (6) Bigeye
  (4) Albacore (5) Bluefin (1)
• Billfish Striped marlin (4) Blue marlin (3),
  Black marlin (2), Swordfish (2)
• Sharks Galapagos shark (1), Tiger shark (1)
• Others Mahi mahi (3), Indo-Pacific sailfish
  (1) Eastern spinner dolphin (1)
  Coastal spotted dolphin (1)

6
YellowfinSkipjack 7.8 -11.5 V, 3.9FO
Yellowfin 2.2V, lt1 FO
BigeyeYellowfinSkipjack
Tunas
Bigeye,Yellowfin
Skipjack Yellowfin
SkipjackYellowfin
Study locations Tunas
7

Blue Marlin
Marlins
Blue Marlin Striped Marlin
Black Marlin
Striped MarlinBlue Marlin
Study Locations Billfishes
8
Summarized Data Reveal Substantial Predation on
Skipjack Tuna
9
Summarized Data Show Variation by Ocean Region
10
Why do we need primary data?

• Summarized data dont allow us to address
• Size-structure of feeding relations
• Variation in feeding due to
• Location
• Method of Capture
• Season
• Other confounding variables

11
Why the details matterSize Selectivity and
Cannibalism
Juvenile Skipjack account for 10 30 of adult
skipjack diets What does this mean for juvenile
skipjack ? How many survive?
12
Size structure of feeding is critical
21
4
2
Results based on age-structured modeling analysis
13
A new culture of data sharing

• We can all benefit from a centralized database
• Without archival efforts, hard earned data have
  limited life span
• Some questions can only be addressed via
  synthesis of many studies
• Archival and analysis promotes serendipitous
  discoveries

14
Trajectory of Data Usefulness
Traditional Model
New Vision
Inter-site synthesis
Publication
Serendipitous Discovery
Retirement
Information Content
Information Content
Gradual Increase in Data Value
Death
Time
Time
From Michener, W. Ecoinformatics managing
data, rescuing data and changing the scientific
culture
15
But Im not done with my data yet

• This new culture of data sharing also requires an
  ethic of data use
• No data will be used without the permission of
  the provider for a specific requested use
• We are developing guidelines to ensure fair data
  use and exchange

16
Want to learn more?
www.fish.washington.edu/tunapred
Funding is provided by Pelagic Fisheries Research
Program