FISHERIES MANAGEMENT Flashcards
what does MSY calculations consider
catch size + age composition (ensuring enough young fish survive to reproduce)
MSY weaknesses
- Assessment results often ignored as “not precise enough”
- Assessment methods failed badly
- Failure to implement short term changes needed for the long term goals
- Violation of the model assumptions
what is the Ecosystem based management approach (EBM)
management that surfaced due to single species management only focusing on understanding the species and not their ecosystems
who decided on the correct definition of sustainability
hillborn
what were the 2 rejected definitions of sustainability
- fisheries can provide a long term constant MSY
- Preserving intergenerational equity – if stocks can rebuild within a generation
what was the accepted definition of sustainability
Maintaining a biological, social, and economic system
- biological = producing as much harvest in long term with min impact on env + non-target species
- social = Spreading employment, income + maintaining traditional communities
- economical = Economically as efficient as possible -> profit
Examples of sustainable managed fisheries
Pacific halibut
Bristol bay sockeye salmon
pacific halibut life history characteristics
500lb
Mature at 12yrs
Vulnerable to fishing at 8yrs
Live for 55yrs
*Life history characteristics means they should be vulnerable
how did pacific halibut become sustainably managed
- US and CA formed the International Pacific Halibut Commission (IPHC) in 1923 -> recognised overfishing danger
- IPHC consists of: 3 commissioners, director responsible for administration, 30 scientists conducting stock assessments and research
Sustainable Management Strategies used for pacific halibut
- Allowable harvest (CPUE, directed surveys, tagging, age structure)
- ITQ – individual transferable quotas
One of the worst examples of socioeconomic management
Before ICQs, the U.S. had open-access fisheries -> led to overfishing, dangerous working conditions, and economic instability.
Bristol bay sockeye salmon life history characteristics
Spawn once and die
Go back to lake to spawn
Caught on Mountains of the rivers before spawning
Native americans
Industrial fishing 1893 – 10million/yr
Fluctuations in catch (Climate fluctuations, Drift net fishery, Increased no of salmon allowed to spawn)
Sustainable Management Strategies used for Bristol bay sockeye salmon
managed by dept of fish + game
- set a target number of salmon that must escape fishing and reach spawning grounds -> numbers reviewed every 3–5 years
- use counting towers to estimate escapement + adjust number of fishing days based on salmon population counts
- Different districts are managed by biologists who monitor salmon numbers using surveys and stock assessments
- aerial surveys, limited entry permit
primary fishing method used to harvest Bristol bay sockeye salmon
Gill Nets
when did pacific halibut become sustainably managed
Stock Status in the Late 1970s reached record levels due to efficient management
- this fishery also had very little bycatch
Challenges in the Bristol Bay Sockeye Salmon Fishery
- Loss of Nutrient Cycling - removing too many salmon before they reach spawning grounds means they won’t die naturally in the rivers and release nutrients
- Social System Effects - limited entry helps maintain sustainability and economic stability but small-scale fishers struggle to afford entry - they have historically relied of salmon harvesting
5 things we learn from successfully sustainable fisheries
- Biological Basis for Sustainability
- Scientific Basis for Sustainability
- Economic Factors in Sustainability
- Management Basis for Sustainability
- Social Considerations for Sustainability
explain the Biological Basis for Sustainability
- Harvesting has minimal impact to habitat + minimal bycatch
- Non-destructive fishing practices
- Targeting species that are less vulnerable to capture – after sexual maturity + if females can be excluded + non schooling species + natural refugra
- High intrinsic rate of increase
explain the Scientific Basis for Sustainability
- Ability to count the fish
- Understanding of life histories + species stock structure
- Ability to track changes in abundance
explain the Economic Factors in Sustainability
High prices + low cost of fishing = overfishing
explain the Management Basis for Sustainability
- Unified jurisdictions
- Power = ability to regulate harvest
- Resources
- Scientific tools
explain the Social Considerations for Sustainability
- Long term interests of all stakeholders
- Community ability to live with flux in yield – diversification of fisheries
