《海洋生物資源評估》課件11 第十一章 漁業(yè)管理

1、漁業(yè)資源管理：Biological reference points and fisheries management本章內(nèi)容：Biological reference points Harvest control rule; Uncertainty and Precautionary approach to fisheries management;漁業(yè)管理捕撈活動漁業(yè)資源資源評估Exploited population Fisheries monitoring programsSurvey programOther informationStock assessment databaseA

2、ssessment model development and testingStock assessmentStatisticsHistorical and current stock abundance and fishing mortalityManagement reference pointsManagement objectivesDetermine fisheries population statusRisk analysisAlternative TACsSelect TACDistribute TACOther management regulations (e.g., s

3、eason, area, MLS, mesh size, trip limit, days-at-sea, bycatch, etc.)Education, enforcement, and compliance漁業(yè)管理中需要考慮的因素The objectives of managing the fishery;Present state of development and exploitation of the fishery;Critical habitats;Management strategies;Regulations; Impacts on the ecosystem.管理的總

4、體目標(biāo)：Maintain resource productivity;Resolve conflicts among stakeholders; andPromote efficient use of the resourcesObjective: reduce the likelihood of overfishing (growth and recruitment overfishing) while maximizing fisheries output;指標(biāo): Control the level of fishing mortality to avoid “overfishing”;M

5、aintain optimal level of stock biomass to avoid stock being “overfished”;過度捕撈的類型7/11/20227對于不同物種，漁業(yè)管理的關(guān)注點不同：Short-lived species with high fecundity (e.g. sardines and penaeid prawns): large fluctuations in recruits and stock sizes, density-independent factors more important, large variations in catc

6、hLong-lived species with low fecundity (e.g., deep-water fish): strong spawners-recruits relationship, density-dependent factors more important, more constant yield. 7/11/20229大西洋鱈魚漁業(yè)管理的目標(biāo)MSYMEYMSCYOSYOY7/11/202212管理策略 Management strategiesA plan stating how the catch taken from the stock will be ad

7、justed from year-to-year, depending upon management objectives, the size of the stock, knowledge on the biology of the species and ecosystem, and degree of uncertainty regarding dynamics of the stockIt is not a set of annual regulations, and should not be adjusted from year to year.管理措施的類型Approach:

8、Input-control;Output-control; Combination of input- and output-controls.Management regulations 管理規(guī)則Based on the results of stock assessment輸入控制 Input-control management strategyControl input fishing effort to maintain fishing mortality rate at a desired levelRestriction of fishing gearsRestriction o

9、f fishing effortsClosureClosure 禁漁/休漁Temporal closure and spatial closure or their combinationsSeasonal closure: spawning, recruitment, meat qualityRotational closure and periodic closure:Area closure: juveniles and spawning stocks海洋保護(hù)區(qū) MPA:A marine protected area is often a large area divided geogr

10、aphically into smaller areas, or zones, in which various restrictions on human activities and exploitation are appliedTypes of restrictions:Preservation zones, Wildness zones, Recreational zones, Traditional fishing zones, Scientific zones, Experimental zonesMPA的目標(biāo)Protection of ecosystem structure,

11、function, and integrityIncreased knowledge and understanding of marine systemsImproved nonconsumptive opportunitiesPotential fishery benefitsMPA 對于漁業(yè)的意義Protect a section of spawning stock biomass: overspill Protect critical fisheries habitatsPreserve natural stock structurePrevent size-at-age from d

12、ecreasingSimplify enforcement and compliance, reducing management costsMPA設(shè)計需要考慮的因素Considerations in proposing MPAs include:Size;Location: key habitats, key speciesPermanency of protected areasMPA 的計劃需要包括以下信息The areas present and historic ecological status (including any environmental degradation no

13、ted) and a description of natural habitat boundariesPresent and historic use of the area, an assessment of any incompatibility between these uses, and the claims of and conflicts between various user groups or stake-holdersThe management strategies and tactics/regulations which should be applied to

14、the area, its use and development, including the recommended zoning within the MPA, likely benefits, enforcement costs, and how the stake-holder groups may be accommodated輸出控制 Output-control management strategyControl output production of a fishery, mainly catch, to maintain fishing mortality rate a

15、t a desired levelConstant stock sizeConstant fishing mortality rateFixed escapementConstant catchQuota：配額Sex-specific harvestingSize-limit strategiesEconomical harvest strategy兩種管理策略的不足之處：Input control: temporal changes in fishing efficiency and fish distributions, require good information about fis

16、h biology and ecology, knowledge about fishermens fishing behaviorOutput control: difficult to regulate, require high quality of stock assessment, 漁獲規(guī)則/管理措施 ：Harvest tactics / regulationsA set of annual regulations used to implement the strategy to achieve predefined objectives; May change from year

17、 to year.漁業(yè)評估管理中的不確定性uncertainty in stock size, vulnerability/catchability, and effort on different tacticsStock size well known: TAC effective for any harvest strategyVulnerability/catchability well known:Effort limits are effective for any harvest strategyEffort well known:Still depends on uncerta

18、inty in stock size and V/C漁業(yè)管理策略與規(guī)則的比較管理措施歸納表12.37/11/202227管理措施的執(zhí)行Enforcement of regulationsRegulations must be enforced.Enforcement includes education and prosecutionEducation: makes the users aware any regulations and the reasons for their imposition.Measures: public meetings, radio talks, press

19、articles, poster displays, mails, etc.Goals: long-term interests of the community強制執(zhí)行的方式Prosecution: 訴訟Penalties applied must be significant to the offender and relevant to the offence.Penalties include: a large fine, gear confiscation, reduced/revoked quota, revoked fishing seasons, Enforcement sta

20、ff should receive training in public relations, fisheries management, evidence collecting, and court proceduresThey often work in pairs, for safety reasons and in order that corroborative evidence is available in prosecution執(zhí)行成本 Enforcement costs:One of the key factors in considering alternative man

21、agement strategies and regulationsTend to be very expensive Open-sea water: fisheries patrol vesselsCoastal waters: a large number of fishing portsCosts for preparing documents for prosecution The relationship between fish stock assessment, management objectives, management strategies, and managemen

22、t tactics/regulationsExample SFA Control RuleStock Biomass051015202530Fishing Mortality or Catch0.000.050.100.150.200.25 FMSY LimitBiomass Target (e.g. BMSY)OverfishingNo OverfishingOverfished Not OverfishedFTargetFThresholdBiomass Limit (e.g. BMSY/4)生物學(xué)參考點 biological reference pointsNumbers - usual

23、ly a fishing mortality rate (F) or stock biomass level (B) used as a benchmark or guidepost when:Scientists describe stock status and recommend management options“Fishing mortality rates are above/below FMSY ”“Reduce/increase fishing mortality to levels below FMSY”Managers describe goals and make de

24、cisions“Goal to maintain biomass near BMSY”“Reduce/increase fishing effort to achieve FMSY”Policy makers write laws that define policy (Sustainable Fisheries Act for federally managed stocks)“Optimum yield defined as MSY as reduced by relevant economic and social considerations”生物學(xué)參考點的特點Usually a fi

25、shing mortality rate or biomass level related to a common management goal and calculated in a standard wayOften treated as exact but, from a technical point of view, just another estimate with uncertainties of all kinds Measurement errors, model mis-specification, etc.The best reference points are r

26、obust, easy to understand, easy and non-controversial to calculate何時需要用到BRPWhen they facilitate communication and understandingWhen they help managers move towards their goals Goals and policy can be implicit and commonsensical (e.g., keep catches and revenues high)Or explicit and legal (i.e., FMSY

27、in the Sustainable Fisheries Act)Or both7/11/202235 of 89BRP類型：Target and threshold reference points目標(biāo) “Targets” for what managers want to achieveLike speed limit signs to achieve fast, safe transport (balancing speed and risk) 閾值 “Thresholds” for what managers want to avoidLike the yellow line on a

28、 highway (you can cross them but. . .)Trigger attention and concernUsed increasingly because managers tend to stray from their targets, particularly in fisheries with excess capacity 極限 “Limits” are special thresholds Like the “wrong way” sign on an rampIndicate need to take drastic action7/11/20223

29、6 of 89捕撈死亡率參考點：Fishing mortality reference pointsMany flavors, long historyUsually based on one of three types of models:Surplus productionSpawner-recruitYield-per-recruit modelsExample targets for MSY goals: FMSY or “proxies” like FMAX, F0.1, F35%, F40%, F45%Example targets for status quo manageme

30、nt goalsFRep, FStatusQuoExample limit reference points FCrash, FLo, F10%Catch sometimes used when F is not estimated生物量參考點 Biomass Reference PointsFewer, most from surplus production models, historical data, or ad-hocUsually biomass or numbers of fish but relative indices often usedCommercial catch

31、per unit fishing effortMean catch per tow in a surveyExamples: Targets: BMSY, BStatusQuoThresholds: BMSY/2Limits: BMSY/4, some specified tonnage (e.g., 50,000 mt for Pacific sardine)Fishing mortality BRP vs. biomass BRP?F reference points more important F easier to control via catch, fishing effort,

32、 closed areas, seasons, etc.The easiest way to affect biomass is by controlling FF limits and thresholds are more like “early warning” signalsIts already too late when biomass is low and you hit a biomass limit生物學(xué)參考點需要與實測數(shù)據(jù)對照Reference points imply ongoing data collection/assessment activityReference

33、 points are meaningless without data collection or stock assessmentsMust measure something (e.g. F, biomass, catch) for comparison to the benchmarkBRF用于指導(dǎo)漁業(yè)管理What will managers do to move towards their target and to avoid thresholds?Reference points without management actions have a technical meanin

34、g but no practical significanceRelated policy/technical questions:How quickly can/will managers/bureaucracy react if a threshold is crossed?What sort of measures are managers willing or capable of using?不同資源狀態(tài)下的管理策略BRP應(yīng)用的系統(tǒng)構(gòu)架Policy and goalsAttitudes towards riskTargets for management goalsThreshold

35、 & limit reference points For what managers want to avoidData collection and stock assessmentsManagement actionsAll tailored to biologyResiliency and uncertainty All built around logisticsWhat is practical?BRP系統(tǒng)需要面對的問題Will the whole package help managers go where they want to be and help them stay t

36、here?Ideally answered by simulation model analysis, but often argued by analogy or experienceMany small questionsHow do the reference points relate to management targets and goals?Are the benchmarks measurable?Are the data/estimates sufficiently precise?Is the work load reasonable?Are legal requirem

37、ents addressed?Does the package require management actions that are unrealistic (too frequent, too drastic, too expensive, too unpopular)?The package as a “Control rule” or “Harvest rule”Control rules lay out goals, reference points, data, and expected management reactions in key situationsUse techn

38、ical and management resources efficientlyThe control rule is debated once in view of goals, data precision, uncertainty and other factorsRelatively easy to analyze because the pieces are all thereMakes technical analyses feasibleUsed in most federally managed fisheries, widely advocated by FAO7/11/2

39、02246 of 89SFA Control Rule-Key Aspects （Sustainable Fisheries Act）Manager has MSY goals;Manager wants to avoid depleted stocks;F goes down as biomass falls below target (precautionary principle);Separates targets and limits (important!);Distinguishes between “overfishing” (high rate) and “overfishe

40、d” (low) biomass levels;Targets for F and B, a threshold for B and limits for F and B; Generic approach applicable to many species;Policy balances production (MSY) against risk (minimize chances of overfishes stocks);Idealized MSY Control RuleStock Biomass051015202530Fishing Mortality or Catch0.000.

41、050.100.150.200.25FMSY or Max. Catch ThresholdBiomass Limit (e.g. BMSY/4)Biomass Target (e.g. BMSY)OverfishingNo OverfishingOverfished Not OverfishedTargetExample 1: Six Tiers of Alaska Groundfish One policy and one control rule “Tiers” depend on data & uncertaintyE.g. Tier 2 means B, BMSY, FMSY, F3

42、5%, and F40% estimates availableE.g. Tier 6 means catch data onlyAcronyms and symbols: B=current biomassFOFL is the fishing mortality thresholdFABC is F for allowable biological catch ( FOFL)F35% and F40%=5% biomass limit parameter, i.e. F=0 when BFOFLStocks overfished when:B BMSY/2 orB FMSY)Overfis

43、hed means low biomass (e.g. BBMSY)FOFL = FMSY FABC = FMSY x (F40% /F35%) B more than threshold but less than target (5% B/BMSY 1)FOFL = FMSY x (B/BMSY - 0.05) / 0.95FABC = FOFL x (F40%/F35%)B below threshold (overfished, B/BMSY = )Exploited population Fisheries monitoring programsSurvey programOther informationStock assessment databaseAssessment model development and testingStock assessmentStatisticsHistorical and current stock abundance and fishing mortalityManagement reference pointsManagement objectivesDetermine fisheries population stat