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Icthyology

Fishery science & related disciplines. fish ecology. Icthyology. Ecology Limnology Oceanography. Fishery Science. 3 major groups 1) Jawless fish: lamprey and hagfish 2) Cartilaginous fish: sharks, rays, and chimaeras . http://www.flmnh.ufl.edu/Fish/Education/GroupsFish/FishGroups.htm.

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Icthyology

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  1. Fishery science & related disciplines fish ecology Icthyology Ecology Limnology Oceanography Fishery Science

  2. 3 major groups 1) Jawless fish: lamprey and hagfish 2) Cartilaginous fish: sharks, rays, and chimaeras http://www.flmnh.ufl.edu/Fish/Education/GroupsFish/FishGroups.htm

  3. 3) Bony fish • coelacanths and the lungfishes (fleshy-finned or lobe-finned fishes) • B. ray-finned fish • sturgeons and paddlefish (primarily cartilaginous fish showing some ossification) • gars, bowfins (bony fish that show primitive characteristics) • telelosts (more derived bony fish; largest group)

  4. Disclaimer The following is a brief tour of some common and ecologically important U.S. fish They are presented roughly in taxonomic order from primitive to derived Only ~ 11 types presented- many more Focus on associating body shape, mouth, & other characters with ecological function

  5. **Ray-fined but not teleost Gar: elongate body, large mouth Lie-in-wait predator; fast sideways lunge http://commons.wikimedia.org/wiki/Image:Gar_shedd.jpg Lake sturgeon; mouth on bottom eats bottom mollusks etc… http://www.dcnr.state.pa.us/wrcf/lsturg.aspx

  6. http://www.webzone.net/randys/fish_index.htm Paddlefish (Polyodon spathula) filters zooplankton **Ray-fined but not teleost

  7. A few common freshwater telelosts of North America American Eel (Anguila rostrata) http://www.utexas.edu/depts/tnhc/.www/fish/tnhc/na/naindex.html http://www.bbsr.edu/cintoo/microbial_observatory/mo_sargasso/mo_sargasso.html

  8. Salmonids, lake trout open water predator Pikes: northern pike, long body & big mouth, lie-in-wait predator, weedy areas http://www.d.umn.edu/cla/faculty/troufs/Buffalo/images/Shedd_NorthernPike.gif

  9. Minnows: mostly small, many species, can be hard to ID Fat head: eat invertebrates http://dwrcdc.nr.utah.gov/rsgis2/search/Display.asp?FlNm=pimeprom Common carp: introduced, highly prized for sport elsewhere; mouth on bottom eat anything, uproot vegetation captured by Dieter Markus Stein 17 December 2006 at 83.93 lbs

  10. Catfish: brown bullhead, down-turned mouth; eat bottom inverts & fish http://www.flmnh.ufl.edu/fish/Gallery/Descript/LongnoseGar/LongnoseGar.html Siversides: Brook Silverside Long thin fish adapted to quick, darting motions; upturned mouth feeds at surface http://www.webzone.net/randys/fish_index.htm

  11. Sunfish & basses Longear Sunfish Deep bodied fish are maneuverable & often in littoral zone http://www.utexas.edu/depts/tnhc/.www/fish/tnhc/na/naindex.html Smallmouth bass: littoral zone predator

  12. Percids Darters, rainbow darter, small mostly streams, eat inverts, showy males Walleye: open water predator http://www.nature.org/wherewework/northamerica/states/ohio/bigdarby/habitat/art19457.html Great lakes & inland, big sport fishery http://www.columbiariverwalleyefishingguides.com/

  13. Dramatic changes can occur across a fish’s life history Change in size and appearance Change in “niche” what they eat, habitat

  14. Yellow Perch Adult (>150 mm) Larvae (~8mm) http://www2.uqtr.ca/GREA/en/proftechs.php?id=3 http://www.dnr.state.md.us/fisheries/fishfacts/art/EPA%20-%20Photographs/yellow_perch_PIB_Img_0928_web.jpg Most larval fish eat zooplankton Marine larvae very small High Adult diets diverse Adult size varies w/ spp. Continue to grow throughout life- old fish very big

  15. Assigned reading Pauly et al. 2002

  16. UN-Food & Agriculture Organization statistics World consumption of fish increasing, especially China- though doubts about reporting from china exist

  17. Capture fishery = wild fish & other spp. caught from Oceans, Lakes & rivers Aquaculture = fish & other spp. raised in ponds or floating cages

  18. A few areas eat lots of fish, some almost none

  19. Goal of Capture Fisheries Determine maximum harvest that can be taken without impairing the prospects of exploiting the fishery in the future How many fish can be taken without destroying the stock? traditionally thought of as Maximum Sustainable Yield (MSY) Most recent thinking suggests that more holistic view should be taken…… we’ll talk about why.

  20.  Fisheries science began in it’s modern form between WWI & WWII  Much work by fishery scientists estimating how much can be taken. Many methods & models.  Many technical aspects derived from basic population biology

  21. harvest growth  K Hypothetical fish population responds to harvest regimes assume “s-shaped” population growth K Biomass Time

  22. K 2 max growth, end exponential phase Remember basic population biology…….. K K growth rate (r) population size 2 0 K Time 0 Population size

  23. small harvest slower growth, top of S curve Hypothetical fish population responds to harvest regimes K Biomass Time

  24. keeps biomass oscillating around K/2, highest growth rate, leads to MSY regular harvests Hypothetical fish population responds to harvest regimes K Biomass ½ K Time

  25. population drops to non-viable level- below critical number Hypothetical fish population responds to harvest regimes frequent harvest K Biomass Time

  26. K Biomass Time Hypothetical fish population responds to harvest regimes recovery takes time  generation time  survival

  27. borderline between 2 scenarios can be fine line  spatial variability  temporal variability  other species  inaccurate biomass estimate MSY can be risky K Biomass Time

  28. Linda Greenlaw, captain of the Hannah Boden claimed in her book The Hungry Ocean that sword fish stocks have not declined since she has been fishing.

  29. 20000 15000 Total N. Atlantic swordfish catch (mt) 10000 5000 1975 1980 1985 1990 1995 2000 Year Total catch data for North Atlantic swordfish from the International Commission for the Conservation of Atlantic Tunas (ICCAT), the management agency responsible for the conservation of tunas and tuna-like species in the Atlantic Ocean and adjacent seas.

  30. 20000 15000 Total N. Atlantic swordfish catch (mt) 10000 5000 1975 1980 1985 1990 1995 2000 Year What biological or economics information do we need in order to assess the swordfish catch data? How might this additional data help explain trends in the catch?

  31. Climate= source of uncertainty Interacts with fishing Natural year to year variation Climate change models predict more extreme events

  32. Individual stocks can crash….. South American anchovies were ~20% of world catch at this time Heavy fishing maintained during El Nino year.

  33. Normal year Warm surface water pushed west, sea surface ~ .5 m higher at Indonesia than at Ecuador Surface temp ~ 8 C cooler off South America, due to an upwelling of cold water from deeper levels Cold water is nutrient-rich, supports high levels of primary productivity, Trade winds http://www.fnoc.navy.mil/PUBLIC/

  34. warm surface water cold high nutrient water Normal Year Asia Trade winds South America

  35. El Niño Asia South America Trade winds warm surface water cold high nutrient water

  36. Are world fisheries being overfished?

  37. ratchet effect When fisheries scientists give information indicating overfishing, but Political pressure to keep harvest rates, for economic well being. Catches of northern cod

  38. Despite repeated warnings of Canadian fisheries scientists, some of whose voices were quelled by their superiors, catches were allowed to exceed the biomass of the spawning stock. Crustaceans (lobster, shrimp) Water column fish Bottom oriented fish Not just cod catches down, many species

  39. http://www.sethwhite.org/animals.htm

  40. Despite individual stock crashes, according to world Food & Agriculture Organization (FAO) total marine catch is going up.

  41. But…… effort has been increasing …. the ratchet effect in action? source FAO rate of increase slowing In addition to  # ships, technology (catch efficiency) has improved

  42. Trophic level of catch is decreasing • Assume that fisheries switch to low trophic level species in response to abundance • This idea recently criticized, will be discussed in trophic cascade lecture

  43. Aquaculture Low tech High tech http://www.mar.dfo-mpo.gc.ca/sabs/farm.htm High inputs of fossil fuel, animal feed Low inputs: human labor (calories), dung & other organic fertilizer http://www.msu.edu/~rileypam/fish/ff.html

  44. Nile tilapia pictured in Auburn, AL Major production areas http://www.ag.auburn.edu/fish/image_gallery/data/media/78/IMG0033.jpg http://www.fao.org/fi/website/FIRetrieveAction.do?dom=culturespecies&xml=Oreochromis_niloticus.xml

  45. Monterey Bay Aquarium: Sea Food Watch

  46. What kind of fish should we eat? Not specific spp, but traits. trophic level habitat wild/farmed more………..

  47. Farming salmon is like farming tigers. Why is this a bad idea?

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