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Some basics and a bit about small pelagics March 30, 2010 FISH/ENVIR 330C announcements Please turn in your 1st day survey Lab assignment #1 is due Friday, 10:30am Either hand it in to Paul or use the on-line assignment drop box

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some basics and a bit about small pelagics

Some basics and a bit about small pelagics

March 30, 2010

FISH/ENVIR 330C

announcements
announcements
  • Please turn in your 1st day survey
  • Lab assignment #1 is due Friday, 10:30am
    • Either hand it in to Paul or use the on-line assignment drop box
  • 1st reading/lecture quiz is Friday, 10:30-10:40 (don’t be late)
fisheries science
Fisheries Science
  • Marine ecosystems are difficult to observe
    • Multiple trophic levels may lie between primary producers (phytoplankton) and economically, socially, or culturally valuable organisms (cod, sea birds, whales, etc.)
    • And there is also the physical and chemical environment that is changing …
space time scales of ocean processes mantua et al 2002 u s globec issue of oceanography
Space-Time Scales of Ocean Processes(Mantua et al. 2002, U.S GLOBEC issue of Oceanography)

Human caused climate change

Human caused climate change

centuries

Aleutian Low

NorPac High

decades

Boundary

currents

decades

years

seasons

Upwelling

fronts

seasons

eddies

Time (seconds)

days

days

Surface

Mixed

layer

convection

hours

hours

turbulence

seconds

Tide pool

fjord

Ocean gyres

Bay/estuary

Space (meters)

data collection
data collection
  • What we see are generally bits and pieces of information related to ecosystem states and processes
    • It is far easier to observe terrestrial and freshwater systems
slide6

Astoria

4

6

°

N

Tillamook

4

5

°

N

+

+

+

+

Newport

50m

100m

4

4

°

N

150m

Coos Bay

4

3

°

N

4

2

°

N

125° W

124° W

123° W

200m

  • NH-Line Hydrographic and Zooplankton
  • Time Series

100m

50m

  • Bi-weekly Sampling:
  • 1969 – 1973 (Miller, Pearcy, Peterson)
  • 1983 (Miller, Batchelder, Pearcy, Brodeur)
  • 1990-1992 (Fessenden and Cowles)
  • 1996 – present (Peterson et al.)

NH Line

Provided by Bill Peterson, NOAA Newport

sampling methods
Sampling methods
  • Water sampling with CTD, Niskin Bottles, and buckets for hydrography, chl-a and nutrients
  • Mesozooplankton with ½ m 200 um net towed vertically
  • Euphausiids with 70 cm 505 um net towed obliquely

Provided by Bill Peterson

slide8

Collecting long-term perspectives on zooplankton composition and abundance takes a lot of TIME and EFFORT

  • There is a strong inverse relationship between northern (boreal) and southern (subtropical) copepod species
  • changes are rapid and approach order of magnitude differences among years

99

02

92

69-73

83

97

98

Southern Copepod Northern Copepod

Log10(Biomass anomaly) log110(Biomass anomaly)

Modified from Bill Peterson’s original

pacific halibut recruitment
Pacific halibut recruitment

lots of valuable data, in this case “recruitment” estimates come from fishery landings and surveys

From: IPHC Stock Assessment Reports

http://earthguide.ucsd.edu/DFL_ed_prelim/kinds/kinds_commercial.html

recruitment
Recruitment
  • Recruitment refers to the quantity of younger fish surviving the various egg, larval, and juvenile stages to begin to be captured in a fishery.
    • Lots of interesting and important things happen prior to recruitment, in fact a whole series of continuous events that typically winnows down extremely large numbers of eggs and larvae into a much smaller number of recruits
    • The same physical process may affect survival in different ways at different stages of “pre-recruit” development
recruitment11
Recruitment
  • Before recruitment, the target organisms are essentially invisible to humans because they are not taken by any fishery, (though sometimes taken in “pre-recruit” surveys)
  • The conventional paradigm of fisheries science is to aggregate the rich ecology of the pre-recruit period into this single quantity -- recruitment
stock recruit relationships tend to be very noisy
Stock-Recruit relationships tend to be very noisy
  • The deviations of the data points from the model (shown by the curve) are often referred to as environmental noise
  • This “noise” poses major challenges for fishers and fishery managers

Total recruits (7 year olds)

Effective spawning biomass

the comparative approach seeking signals in the noise
The comparative approach: seeking signals in the noise
  • Controlled experiments, like those in a laboratory setting, are simply not possible for large marine ecosystems
the comparative method offers a valuable alternative
The comparative method offers a valuable alternative

West

Coast of

N. America

  • Here, examine separate realizations needed for scientific inference via recognition of informative patterns in natural phenomena
  • different sets of seasonal or geographic settings, encompassing a range of natural variability in conditions and mechanism, replace experimental treatments

West

Coast of

S. America

inherent limitations
Inherent limitations
  • Comparative results generally conform to the information available at the time they are produced
  • In this realm, we are continuously faced with the challenge of separating mechanistic causality from outcomes based on history and happenstance
the pelagic reproductive strategy
The pelagic reproductive strategy
  • Upwelling zones are among the most productive in the world, with some of the largest fish populations
  • Classic examples lie along the eastern edges of ocean basins

All are known for their rich fisheries and very large populations of small pelagic fish stocks like sardines and anchovies

Bakun and Nelson, 1991, J. Phys. Oc.

the pelagic reproductive strategy17
The pelagic reproductive strategy
  • Upwelling zones are great places for feeding, yet difficult habitats for reproduction
    • Major pelagic fish stocks feeding in the upwelling region undertake extensive spawning migrations in order to avoid placing their larvae in the upwelling zone where they would tend to be swept offshore and dispersed into the open ocean
critter of the day

Critter of the Day

Sardinops sagax caerulea

California pilchard, Pacific sardine, Sardina Monterrey

Family: CLUPEIDAE (Herrings and Sardines)

Image from: http://www.oceanoasis.org/fieldguide/sard-cae.html

pacific sardines
Pacific sardines
  • maximum age: 12
  • age of maturity: 2
  • age of recruitment: 1
  • prey: diatoms, copepods, euphausiids
  • predators: fish, tuna, sea-birds

Large adults

Adults

Summer feeding

Juveniles

Spawning (Feb-April)

processes impacting reproduction
Processes impacting reproduction
  • Temperature:
    • warm years; spawning shifts north
    • development of larvae favoured between 14-160C
  • Stratification:
    • concentrating prey for first feeding larvae
  • Fronts and Meanders:
    • concentrate food for larvae
  • Bloom intensity:
    • spawning in highly productive areas

Spawning (Feb-April)

Slide provided by Sandy McFarlane, DFO

1950 s crash in california s sardines the end of cannery row
1950’s crash in California’s sardinesthe end of “cannery row”

Limited fishery opened

Fishery closed

Barnes, et al. 1992

slide23

Andy Soutar with a Kasten Core from the Santa Barbara Basin

Image from http://www.mbari.org/news/news_releases/2006/forams-images.html

A section of a sediment core from the Santa Barbara Channel showing annual sediment layers laid down each year

Image credit: 2005 David Field

2000 year history of california sardine abundance
2000 year history of California sardine abundance

Biomass (106 metric tons)

Years before present

Baumgartner, et al. 1992

the pelagic strategy puzzle
The pelagic strategy puzzle
  • Because of the reproductive difficulties caused by the disruptive upwelling environment, some suggest that pelagic fish in these regions seldom approach the carrying capacity of their adult habitat
  • So why are anchovies, sardines, and other species that spawn pelagic eggs and larvae dominant species in these regions where loss of reproductive products appears to be such a problem?
  • Even more puzzling is the success of the pelagic reproductive strategy among fishes and invertebrates inhabiting ocean islands and banks. Tropical fish typically posses reproductive habits and behaviors that seem explicitly adapted to cause eggs and larvae to be quickly transported offshore, where they would be most subject to loss.
reminders
reminders
  • 1st day survey is due
  • Assignment #1 due Friday at 10:30am
  • 1st reading/lecture quiz on Friday at the beginning of class (10:30-10:40) … don’t be late