MARS 345019 November 2013Fisheries IIts not all high-techBut a lot of it isPair-trawlers in the North SeaFisheries Management 101:Modeling Fish Populations – Life TablesPopulation in Year 1Population in Year 2Modeling Fish Populations – Life TablesPopulation in Year 1Population in Year 2RR = Recruitment: the entry of new individuals into the populationModeling Fish Populations – Life TablesPopulation in Year 1Population in Year 2(spawners)RModeling Fish Populations – Life TablesPopulation in Year 1Population in Year 2(spawners)REggs  LarvaeModeling Fish Populations – Life TablesPopulation in Year 1Population in Year 2(spawners)RPopulation in Year 3(spawners)Etcetera…Important Recruitment Facts1) Big fish typically produce more eggs2) Older fish are typically biggerAnd 3) Unfortunately, bigger fish are typically more desirable to fishermen“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”Modeling Fish Populations – Life TablesPopulation in Year 1Population in Year 2MortalityModeling Fish Populations – Life TablesPopulation in Year 1Population in Year 2Mortality“Natural” FisheryModeling Fish Populations – Life TablesPopulation in Year 1Population in Year 2RPopulation in Year 3“Natural” FisheryMortalityMortalityNatural mortality0.1 0.001 0.001 0.001 0.001 0.001 0.001 0 0.02 0.05 0.5Fishery Mortality0 0 0.001 0.001 0.002 0.002 0.005 0.01 0.1 0.1 0.5Total Mortality0.1 0.001 0.002 0.002 0.003 0.003 0.006 0.01 0.12 0.15 1Contribution to Recruitment0 0.005 0.01 0.02 0.05 0.1 0.2 0.25 0.25 0.25AgePopulation SizeYoung of the year1234 5678910111,000,000900,000 899,100 897,302 895,507 892,821 890,142 884,801 875,953 770,839 655,213 09,561,679New Recruits 917,4960 4,496 8,973 17,910 44,641 89,014 176,960 218,988 192,710 163,803Life Table for One CohortStarting population for next cohortRepeat as necessary to forecast into future yearsReplace coefficients with mathematical expressions capturing response to environmental variablesTemperatureFaster growthPhysical ProcessesDispersion, movement towards or away frompreferred habitatPreyfood availabilityPredatorsjellyfish, for exampleLarval growth rategrow fast, less time as planktonFactors Affecting RecruitmentRecruitment Success: Critical Window HypothesisFood must be available as soon as yolk is exhaustedHoude 2008Figure 6. Conceptual diagram of the temporal relationship between larval fish abundance (yellow) and phytoplankton biomass (blue). Warmer temperatures = higher growth rates, better survivalKristiansen T, Drinkwater KF, Lough RG, Sundby S (2011) Recruitment Variability in North Atlantic Cod and Match-Mismatch Dynamics. PLoS ONE 6(3): e17456. doi:10.1371/journal.pone.0017456http://www.plosone.org/article/info:doi/10.1371/journal.pone.0017456Match - Mis-match HypothesisFigure 1. Map of four major spawning sites across the North Atlantic (middle) with time-series (1900–2006) of air surface temperature anomaly data for each site.Kristiansen T, Drinkwater KF, Lough RG, Sundby S (2011) Recruitment Variability in North Atlantic Cod and Match-Mismatch Dynamics. PLoS ONE 6(3): e17456. doi:10.1371/journal.pone.0017456http://www.plosone.org/article/info:doi/10.1371/journal.pone.0017456Figure 2. Time series of surface temperature reveal both colder (e.g. 1960's) and warmer (e.g. 1990's) time periods relative to the climatology (1961–1990).Kristiansen T, Drinkwater KF, Lough RG, Sundby S (2011) Recruitment Variability in North Atlantic Cod and Match-Mismatch Dynamics. PLoS ONE 6(3): e17456. doi:10.1371/journal.pone.0017456http://www.plosone.org/article/info:doi/10.1371/journal.pone.0017456Figure 5. The relationship between number of recruits (millions), temperature anomalies, and 0-group index (index for number of juveniles).Kristiansen T, Drinkwater KF, Lough RG, Sundby S (2011) Recruitment Variability in North Atlantic Cod and Match-Mismatch Dynamics. PLoS ONE 6(3): e17456. doi:10.1371/journal.pone.0017456http://www.plosone.org/article/info:doi/10.1371/journal.pone.0017456Population size(number) of fish(= density)slow population growth (resource limited, stationary)slow population growth (few animals)fast population growth (exponential)population growthdensity**Effects of fishingOverfishing = catching more than the sustainable yield (target: MSY)(MSY)Logistic model, k= “carrying capacity”MSY = “Maximum Sustainable Yield”What is a fish “stock”(not something used in soup)Relatively isolated, Interbreeding subpopulation of fishSalmon stocksChinook Salmon: >36”, >30 lb, 4-7 yrCoho Salmon: 8-12 lb, 24-30”, 3-5 yrHow 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 ship= 1/3 total catchcarnivoresdemersalcont. shelfcarnivoresopen oceanWhat kinds of fish are caughtUS Beef Consumption in 2000 was 16.8 million metric tonsplanktivoresschoolingshallow, coastalWhere 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 catch1 metric ton = 1 m3of water = 1,000 kg = 2,200 lb= 10 (small) football playersWorld marine fisheries catch, all species = 77,000,000 metric tons in 2000World Marine Fisheries Catch =770,000,000 football playersor ~7,700 Sanford Stadiums fullPER YEARor ~50 kg/personWhere does it go?Mostly NOT food for peopleChicken and other animal feed