intro to fisheries management

Question 1

4 steps to fisheries management

Answer 1

1.collect data
2.asses stays of stocks
3.set catch targets
4.make regulations

Question 2

what is overfishing essentially

Answer 2

exceeding the reproductive capacity of fish - causes a decline, and possibly collapse, in the stock.

Question 3

3 types of overfishing

Answer 3

growth overfishing
recruitment overfishing
ecosystem overfishing

Question 4

what is growth overfishing

Answer 4

• Harvesting fish before they have a chance to reach their full growth potential - fish are harvested at an average size that is smaller than the size that would produce the maximum yield per recruit.
• Reduces average mass of individuals in the catch

Question 5

what is recruitment overfishing

Answer 5

• Reducing a stock so much the spawning stock is too low for the stock to maintain itself.
• Leads to population decline

Question 6

what is ecosystem overfishing

Answer 6

Altering the balance of the ecosystem by overfishing

Question 7

wats Maximum sustainable yield

Answer 7

The largest yield that can be harvested from a stock indefinitely

Question 8

3 ways to control catches

Answer 8

limiting catch
limiting fishing efforts
limiting access

Question 9

how can we limit catch as a way to control catches

Answer 9

• Minimum landing sizes - creates a large number of discards (minimum mesh sizes remove this problem, but choice of mesh is complicated - fish of different species are different sizes)
• Directing technology (e.g. Minimum Mesh
  Sizes)
• Catch quotas

Question 10

how can we limit fishing efforts as a way to control catches

Answer 10

• Prohibiting technology (e.g. types of nets)
• Limit on number (fish traps) or size (nets)
• Restricting number of vessels
• Limiting average time at sea - essentially creates “seasons” - bigger populations allow longer seasons

Question 11

how can we limit access as a way to control catches

Answer 11

Marine reserves - Marine Protected Areas (MPAs, No-Take Zones..)

Question 12

The problem with minimum mesh sizes as a way to limit catch

Answer 12

• Eggs are produced in proportion to a fish’s volume, which is proportional to the cube of its length
• More importantly, older, larger female fish produce eggs and larvae that are much more likely to survive
• Larvae of 12-year-old rockfish grew four times faster
  than larvae produced by 5-year old fish - longer in plankton = more time to be eaten

Question 13

what is a Total Allowable Catch (TACs)

Answer 13

catch limits (quotas), expressed in tonnes or numbers, set for most commercial EU fish stocks
- In the EU, each country is given a quota based upon the calculated TAC and their traditional share (as a
percentage)
- this creates a high amount of discards - so the EU has applied a Discard Ban
- Fish with known high survival rates are to be released alive - all other fish caught would be landed and counted against the quotas
- Undersized fish can only be sold for fish meal or pet
food production
- Fish caught in excess of individual quotas can be
marketed normally but quotas must be bought or leased from another vessel owner in the same member state

Question 14

the main purpose of the discard ban

Answer 14

to increase selectivity in fisheries, especially through the use of technology

Question 15

what is Regional Fisheries Management Organisations (RFMOs)

Answer 15

dedicated to the sustainable management of
either species or areas - some have a purely advisory role, most have management powers to set catch and fishing effort limits, technical measures, and control obligations

Question 16

what’s B/BMSY when working out current fishery status

Answer 16

biomass scaled by biomass at maximum sustainable yield
- < 1 = overfished stock

Question 17

what’s F/FMSY when working out current fishery status

Answer 17

fishing pressure scaled by the fishing pressure
that would generate maximum sustainable
yield
- > 1 = overfishing

Question 18

what’s the Relationship between B/BMSY and F/FMSY

Answer 18

• EXAMPLE 1: a small-scale fishery with biomass B/BMSY = 0.3 (overfished) and fishing pressure F/FMSY = 1.7 (overfishing) would actually be near bionomic equilibrium. Biomass and profit would be
  low, but stable from year to year. Because the stock has been overfished, the catch is also small—in this case, it is just one half of MSY
• EXAMPLE 2: a fishery with B/BMSY = 0.4 and F/FMSY = 2.5; biomass is lower than optimal and still declining. Despite the low biomass, fishing mortality is so large that harvest remains high (in this case =
  MSY). Ultimately, this pressure will reduce the stock, but the inevitable economic and food provision consequences of that overexploitation have yet to be realized.

Question 19

what are the 4 objectives to sustain healthy marine ecosystems and the fisheries they support

Answer 19

(i)avoid degradation of ecosystems, as measured by indicators of environmental quality and system status
(ii) minimize the risk of irreversible change to natural assemblages of species and ecosystem processes
(iii) obtain and maintain long-term socioeconomic benefits without compromising the ecosystem
(iv) generate knowledge of ecosystem processes sufficient to understand the likely consequences of human actions

Question 20

why does Ecosystem-based management differ from management based around single (or even mixed)
species

Answer 20

A fishery could be considered overfished within the ecosystem plan (ecosystem overfishing) when it is not overfished in a single-species context
E.g. When overfishing of large predators causes food web shifts

Question 21

what 2 hypothesised processes are Fish biomass exported from MPAs based on

Answer 21

• Enhanced spawning stock biomass (very difficult to conclusively demonstrate)
• Export of adult fish to areas open to fishing through spillover - either density-independent or density-dependent movements

Question 22

what 5 key features do global conservation outcomes depend on marine protected areas with

Answer 22

NEOLI (No-take, Enforced, Old, Large, Isolated) - Edgar et al. (2015)
1. Degree of fishing permitted within MPAs
2. Level of enforcement
3. MPA age
4. MPA size
5. Presence of continuous habitat allowing unconstrained movement of fish across MPA boundaries
- recovery of fish biomass results dramatically improve when MPA possesses 4 or more NEOLI features

Question 23

what could happen in 2050 according to Costello et al (2016) if sound management reforms were applied to
global fisheries e.g. Rights-based Fishery Management (RBFM) + fishing effort for maximum sustainable yield (FMSY)

Answer 23

could generate annual increases exceeding 16 million metric tons (MMT) in catch, $53 billion in profit, and 619 MMT in biomass relative to business as usual.

Question 24

despite different mechanisms to try and control catch numbers, where will the bulk of the increase in fish consumption come from

Answer 24

aquaculture