MARS 345021 November 2013Fisheries IIIts not all high-techBut a lot of it isPair-trawlers in the North SeaStudents:Please access online course evaluations athttps://www.franklin.uga.edu/evaluation/login.php Please fill out formBefore 5 December 2013, Please!!!Final Examination12:00 – 3:00 Thursday December 5Marine Sciences classroom (room 239 Marine Sciences)~2/3 of the points will be from the last 6 lectures~1/3 will be from any of the material covered in the courseScantron formatReview Q/A sessionWeds Dec 4 11:00How are fish caughthookingentangling in netscatching in netsOther (dynamite, cyanide, etc.)“Average halibut range in weight from 4-20 lbs - and are tiddlers compared to this 448lb monster”“Plenty more fish: Lee Beech, left, and Ashley Beech with the 32 stone halibut”Tuna purse seiners, Victoria, SeychellesMid-water trawler, Portsmouth NHTrawler/factory shipUS Fisherieshttp://www.montereybayaquarium.org/cr/cr_seafoodwatch/sfw_gear.aspx= 1/3 total catchWhat kinds of fish are caughtcarnivoresopen oceancarnivoresdemersalcont. shelfplanktivoresschoolingshallow, coastalFinfishMolluscsArthropods77 Million metric tons= 179 Trillion poundsPer Year!Where are fish caught?21.4 2.21.710.52.05.12.70.7 13.80.14.21.62.13.41.511.0The major marine fishing areas of the world, based on boundaries established by the Food and Agriculture Organization (FAO) of the United Nations. Figures refer to the 2002 catches (x 106metric tons) for each region.Four areas yielded 57 million tons in 2002, 81 % of world catchWhere does it go?Mostly NOT food for peopleChicken and other animal feed supplementsPopulation size(Number) of fish(= density)slow population growth (resource limited, stationary)slow population growth (few animals)fast population growth (exponential)population growthAbundance or Density**Overfishing = catching more than the sustainable yield (target: MSY)(MSY)Logistic model:dN/dt = rN(1/(K-N))k= “carrying capacity”MSY = “Maximum Sustainable Yield”Effects of fishingTimeHow do we regulate a fishery at MSY?By the catch, of course!Catch per Unit Effort = CPUEWhat’s wrong with this picture?CPUE assumesAccurate reportingLandings can be under- or (rarely) over-reportedthe “UE” part of CPUE is hard to quantify“C” is reported in different unitsNo change in technologybetter netsbetter bait“fish finders”whole new technologies – factory ships, pair trawlingSame stocks are being fishedNew stocks are reported in same category as existingAre there better ways to collect the data?Stock assessments (abalone some fish)Escapement (Salmon)Spawning effort (herring)Observers (nearly any commercial fleet)How do you manage fishing pressureTraditional approachesTake limitsTake SizeSeasonGearNumber of licenses (boats)These all have the issue of by-catch, cheating, etc.Different paradigm? Tragedy of the CommonsGloucester MA (Kurlansky book) and other locations:Change the licensing structure –not by species but by fishing groundthey’re “your fish” – vested interest in the long run0204060801001201401955 1965 1975 1985 1995 2005Fish Catch (millions metric tons)world totalall aquaculturemarine catch60% totalSource: FAOSo, how are our fisheries doing?Castro and HuberRussiaBerlin Wall FallsAnchovetaFAO State of World Fisheries 2006Watson & Pauly 2001Catch actually decliningWatson & Pauly 2001Catch is actually decliningFor Chinese “data”Effects of fishing (on target species)1. Average size decreases2.Change in age structure3.Population size decreases4.As a consequence of 1 and 3, reproductive effort decreaseslingcodLength in cmPercent of catchEffects of fishing (on other species)Alaska pollockExploitation began in the 1960s. By the 1990s:• average size decreased (43 to 35 cm)• average weight decreased 45%Target organismPredatorPrey(fish food)-+-Fisheries-basedTrophic Cascades:Effects of fishing30 cm19 cmpollockpredatorsBetween the 1960s and the 1990s:• Average size of pollock eaten by sea lions decreased (30 to 25 cm)• % pollock in their diet decreased (58 to 42%)• Sea lion population decreased (300,000 to 66,000)Stellar’s sea lionEffects of fishing (on other species)Target organismPredatorPreyPollockFishingCopepodsSea lionsKittiwakesLeast auklet---+?+OrcasUrchins-Otters+Kelp-kittiwakeleast aukletOther effects of fishing• Bycatch – capture of non-target organisms• Habitat destruction – e.g. dredgingP. Dayton, Science 1998Before AfterFishing down the food webMean trophic level HarvestedSardines and anchoviesTrophic Levels1 2 3 4 5Phyto  ZP  F1 F2 F3Pauly et al. Science 1998Trophic Levels1 2 3 4 5Phyto  ZP  F1 F2 F3Change in catch 1970 to 2000 Myers & Worm 2003Catch of Top Predators10% of pre-exploitationCPUE dataSize of ‘Great Sharks’ landed off Eastern USAverage LengthR. A. Myers et al., Science 315, 1846 -1850 (2007) Dusky SharkTiger Sharkhttp://scienceblogs.com/shiftingbaselines/http://www.mbayaq.org/cr/seafoodwatch.aspCheck out the video clips on:http://www.shiftingbaselines.org/news/news12.htmStudents:Please access online course evaluations athttps://www.franklin.uga.edu/evaluation/login.php Please fill out formBefore 5 December 2013, Please!!!NOAAThe EndHave a Great Holiday Season and Remember:Eat Mor