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G5: Population ecology (HL)Option G: Ecology and Conservationr and K Strategistsr-strategistsK-strategistsShortLife spanLongReproduce early and oftenRate of reproductionReproduce slowlyLarge numberOffspringFewerUsually smaller body sizeSizeLarger body sizePoor competitorsCompetitionStrong competitorsEarly, low parental careMaturityLate, after long parental careUnstable***Environment***StableZebra mussels, parasites, insectsexamplesHumans, large mammalsr and K StrategistsMost organisms are intermediate, exhibiting characteristics in the mid-range between r and K extremes

D. melanogaster (fruit fly) switches between strategies to suit the environmental conditions

In a predictable environment, in order to maximize fitness, it pays to invest resources in long-term development and long life (K-strategy). In an unstable environment, it is better to produce as many offspring as quickly as possible (r-strategy). Of concern is that ecological disruption favours r-strategists such as pathogens and pest species.

r and K strategists growth curves

Estimating Population Size:Capture-mark-release-recaptureSampling technique that enables you to estimate the number of animals in an ecosystemSteps:Capture a sample of the populationMark them (in an unrestrictive manner)Release back into ecosystemTake a second sample, some will be marked, others notCompare the proportion of marked to unmarkedCapture-mark-release-recaptureMark all Individuals: Practical and ethical considerations when marking animalsHow do we do this?Colour (Paint, nail polish)Tags, bandsMicrochipRadio transmitterWhat limitations are there?Cause no harmCannot make more visible to predatorsDoes not alter behaviourNon-toxicLincoln Index

(n3)(n2)(n1)(N)OR

Population size (N)= (n1 x n2)n3

n1 = # initially caught, marked, and releasedn2 = # caught in 2nd samplen3 = # marked in 2nd sample

Conservation of Fish Stocks5 things you need to know about our oceans:http://www.youtube.com/watch?v=s3u2ZxKhPoAFisheries on the Brinkhttp://www.youtube.com/watch?v=Tf1EgeHDxpAByCatch Problemshttp://www.youtube.com/watch?v=B2E0QQG4Kk4Destructive Trawling Practiceshttp://www.youtube.com/watch?v=m2y_M40tmvgEstimating Size of Commercial Fish StocksStudying catches the proportion of fish stocks taken each yearGathering information from fishersSpawning stock biomass the total mass of mature fish in the populationRecruitment the number of young fish produced each year which survive to spawnLandings the total annual tonnage of fish landed by the fishing fleet

Data is collected by:

Market Sampling landings of fish are sampled to compile information on fish length and ageDiscard Sampling the mass of fish caught and then discarded is measuredResearch Vessel Surveys TrawlingSonarCalculating agesCoded wire tag detectors (capture-mark-recapture)Mathematic modeling

Maximum Sustainable YieldThe maximum average catch that a stock can sustain over a long period of time without jeopardizing the maximum yield in the futureToo small=risk of over fishingToo large=competition for food/resources It is the optimum balance between reproductive rate and growth rate of the stock and the deaths due to harvesting and natural mortality

Harvesting at MSY requires much lower fishing rates than commonly occur in fisheries.It takes a long series of data (>20 years) to adequately calculate a MSY value.

Collapse of fish populations

Northern CodPopulation collapse on the Atlantic CoastMoratorium put into place in 1992 on Northern cod Collapse due to over- exploitation of the stock Meant to last 2 years, but cod population has not rebounded so still closed

Conservation of Fish StocksOverfishing is a huge problem internationally. If the rate of fishing keeps up, by 2048 there will no longer be any commercial fishing.End of the Line trailer:http://www.youtube.com/watch?v=bedirwk95OcFish farminghttp://www.youtube.com/watch?v=B77bs2aploI&feature=relmfuBluefin tunahttp://www.youtube.com/watch?v=dX4v8wyOcns&feature=relmfuCod fisheryhttp://www.youtube.com/watch?v=-OvFpQuJHTM

International Measures to Promote Conservation of FishMonitoring stocks and reproduction ratesTACs (total allowable catches) and quotasClosed seasons (eg breeding season) Creation of no fish zones (exclusion zones, marine reserves)Minimum landing size to discourage the catch of small fishMinimum net sizes so small fish can escapeMoratoria on endangered speciesBanning of drift nets which catch indiscriminately Funding for researchFoster relationships between fishers and scientists

Issues:Enforcement is difficult in international waters and relies on trust and cooperation.Where rules have been respected breeding stocks have recovered.International Conservation MeasuresMonitoring stocks and reproduction ratesTACs (total allowable catches) and quotasClosed seasons (eg breeding season) Creation of no fish zonesMinimum landing size to discourage the catch of small fishMinimum net sizes so small fish can escapeMoratoria on endangered speciesBanning of drift nets which catch indiscriminately Enforcement is difficult in international waters and relies on trust and cooperation.Where rules have been respected breeding stocks have recovered.

http://www.ted.com/talks/dan_barber_how_i_fell_in_love_with_a_fish.htmlhttp://www.ted.com/talks/barton_seaver_sustainable_seafood_let_s_get_smart.html