4: Fisheries & management Flashcards
Give some consequences of fishing
Declines of individual target species
Declines of entire functional groups
Pushing frontiers: further, longer, deeper
Ecosystem impacts
Describe the globalised nature of fisheries
4 countries account for ~20% for all landings on the high seas
Vessels from these countries are fishing progressively further from their home ports
This requires powerful boats, good refrigeration and lots of fuel
Describe how how the globalisation of fisheries is not equitable
Globalisation = not equitable
A few nations dominate fisheries capture
Many fisheries products are exported from regions of low food security to regions of higher food security
Describe by-catch, how it happens and its effects
- No fishing gear is perfectly selective, many are more-or-less indiscriminate
- Large no.s of non-target species are often caught my mistake:
- Fish (non-target species or undersized)
- Marine invertebrates
- Sea mammals
- Reptiles
- By catch often thrown back but don’t tend to survive
- Bycatch can exceed that of target catch!
Give some examples of by-catch
- Albatross hooked by tuna long-lining
- Sharks caught on hooks for swordfish
- Invertebrates caught in trawlers
Describe how fishing can cause habitat destruction
Total area of ocean trawled > area of all forest ever cut down
Some areas e.g North Sea, are trawled multiple times a year
Tawling (like ploughing on land) is damaging to natural ecosystems
e.g beam trawling
Describe a brief history of Fisheries Management
- 1880s first concerns raised about impact of fishing on marine environs (new use of steam powered trawlers)
- Thomas Henry Huxley (Royal commission) felt that major fisheries were ‘inexhaustible’ so no regulation needed
- This attitude has continued into the 20th C.
- Fisheries science since 1850s
Define max sustainable yield in terms of fishing
Relationship between fishing effort and long term average catch
Describe max sustainable yield (MSY)
Av catch will increase as fishing effort increases
But reaches a point where you take more out of pop. that is replaced, so average decreases rapidly
Describe Catch Control (TAC)
= Total Allowable Catches (TAC)
- Set a total limit on amount of a pop. that can be caught, aiming for MSY
- Can be divided into Individual Quotas, which limit the catch of individual boats - all IQs will sum to TAC
- Transferable quotas can be traded between boats
- Allocation of quotas between countries/vessels = source of many international fisheries disagreements
Describe Effort control
- Most of fisheries management is basically about artificially limiting the capacity of the fishing fleet to catch fish
- Limits can be on the number, size, or power of boats, types of fishing gear allowed
- Limits can also be in time (e.g closed seasons) or space (e.g seasonal closed areas, permanent Marine Protected areas)
What may be the best route to making fisheries more biologically, socially and economically sustainable?
Moving to cooperative rather than competitive fisheries
What can we learn from successful fisheries management in richer countries? We need to:
Understand what methods have worked in what social, economic, political and biological contexts
Understand why some stocks have improved much faster than others after a reduction in fishing
Learn how to identify and implement the most appropriate forms of fisheries assessment, management and enforcement
What are Marine Protected Areas?
→ Areas of the sea set aside for conservation aims
- Various terms used e.g MPA/MCZ, Marine Reserve/Park
- These can have specific meanings in certain contexts, but MPA is a useful general term
- Diff MPAs can have diff levels of protection
Do MPAs work? give some examples
Yes!
- Stopping fishing increases fish no.s and species richness
- Biomass typically triples in reserves
- Density increased by ~40%
- Large fish and groups such as sharks benefit particularly from protection
