28_fisheries - Fisheries GS222D.Lund Lecture28...

Info iconThis preview shows pages 1–11. Sign up to view the full content.

View Full Document Right Arrow Icon
Fisheries GS222 – D. Lund Lecture 28
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Overview - this lecture Trophic efficiency Maximum Sustainable Yield – theory and  practice Case studies
Background image of page 2
Trophic efficiency Proportion of food consumed at each trophic  level that is used for growth ranges from 1% to 40% averages 10% most of the food is used in respiration to  provide energy, or excreted as waste
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Do you like sushi? you tuna (top ocean predator) 100 g mackerel (large fish) _____ herring (small fish) _____ copepods (large zooplankton) _____ diatoms (phytoplankton) _____ How much phytoplankton does it take to support 100 g  of tuna?  Assume 10% trophic efficiency.
Background image of page 4
Trophic (in)efficiency i.e., eating sardines is a 1000x more efficient than eating tuna!* 1,000,000 g 1,000 g = 1000
Background image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
If you were eaten by a shark? Trophic efficiency is the proportion of food at each  level used for growth (not for respiration) .
Background image of page 6
The Loch Ness Monster “Nessie” Presence of large monster  would require vast amount  of food in Loch Ness
Background image of page 7

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Fisheries Provide a small fraction (~1 %) of the total human  food supply, but much larger percentage of the  protein World total fish catch is ~80 million tonnes per year ~ 400x weight of the Sears Tower Current catch is ~30% of fisheries production If catch reaches 50% of production (an increase of  1/3), it will likely cause severe damage to the ocean  ecosystem Many fish stocks (e.g. Atlantic cod, Atlantic salmon)  have already surpassed this point
Background image of page 8
Maximum sustainable yield (MSY) 3 primary approaches to fisheries management: 1)   eat lower on the marine food web (copepod  sushi rather than yellow fin sashimi) 2)   marine aquaculture – farm the ocean as we      do the land (e.g. salmon) 3)   use MSY approach – i.e. maximize # of fish  caught while maintaining adequate standing stock  to sustain yield
Background image of page 9

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Maximum sustainable yield (MSY) Standing stock:   biomass of a given population present at 
Background image of page 10
Image of page 11
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 01/20/2012 for the course GEO 222 taught by Professor Davidlund during the Winter '11 term at University of Michigan.

Page1 / 34

28_fisheries - Fisheries GS222D.Lund Lecture28...

This preview shows document pages 1 - 11. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online