An introduction of fisheries management

Question 1

fisheries management

Answer 1

most coastal nations now claim an Exclusive Economic Zone (EEZ) extending 200 nm from their coast. they have sole jurisdiction over these fish stocks

90% of fish caught within 200 nm of the shore; distant water fishers account for ca. 5% of global landings

despite this, commercial spp located entirely within EEZs or associated w/ continental shelves largely continue to decline

Question 2

fisheries management circle (4)

Answer 2

collecting data (recreational reporting, commercial reporting, Scientific Observations, Biological factors -> assessing status of stocks (better assessments based on better data leads to regulations grounded in sound science) -> setting catch targets (better data & scientific research produces more reliable info about the health of fish stocks) -> making regulations (councils & commissions state & federal agencies fishery stakeholders) -> collecting data

Question 3

overfishing

Answer 3

fish stocks have a high reproductive caapcity

this capacity can be exceeded, h/e, causing decline, + possibly collapse, in the stock

Question 4

Growth overfishing

Answer 4

harvesting fish before they have 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

Recruitment overfishing

Answer 5

reducing a stock so much the spawning stock is too low for the stock to maintain itself

leads to pop decline

Question 6

ecosystem overfishing

Answer 6

altering the balance of the ecosystem by overfishing

Question 7

How to control catches

Answer 7

1. limiting catch
   
   • minimum landing size
   • directing technology (e.g. Minimum Mesh Sizes)
   • catch quotas
2. limiting fishing efforts
   
   • prohibiting technology (e.g. types of nets)
   • limit on number (fish traps) or size (nets)
   • restricting number of vessels
   • limiting average time at sea
3. limiting access
   
   • marine reserves

Question 8

Days at sea

Answer 8

limiting time at sea essentially creates “seasons”; bigger pop allow longer seasons

fishing becomes race; industry turns to bigger, faster boats, which leads to shorter seasons

creates gluts/shortages: price crash when boats return

safety implications: boats leave when season is open, regardless of weather

Question 9

Minimum landing size

Answer 9

creates large number of discards

minimum mesh sizes remove this problem, but choice of mesh = complicated (fish of different spp are different sizes)

Question 10

The problem with minimum mesh sizes

Answer 10

eggs produced in proportion to fish’s volume, which is proportional to cube of its length:
- single 61 cm red snapper (Lutjanus campechanus) has been estimated to produce as many eggs as 212 43 cm snappers

more importantly, older, larger female fish produce eggs + larvae that are much more likely to survive

Question 11

Total Allowable Catch (TACs)

Answer 11

TACs = catch limits (quotas), expressed in tonnes or numbers, set for most commercial EU fish stocks

In EU, each country = given quota based upon the calculated TAC + their traditional share (as a percentage)

Question 12

Doesn’t this create high levels of discards?

Answer 12

yes - so EU has applied Discard Ban

fish w/ known high survival rates are to be released alive - all other fish caught would be landed + counted against 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 13

Discard bans

Answer 13

main purpose of the discard ban = increase selectivity in fisheries, esp through the use of technology

Jan-Nov 2018: UK lands almost no undersize cod

Question 14

The high seas

Answer 14

UN Convention on the Law of the Sea requires states to cooperate in conservation + management of fish stocks

primarily done through the establishment of Regional Fisheries Management Organisations (RFMOs) = dedicated to sustainable management of either spp or areas - some have purely advisory role, most have management powers to set catch + fishing effort limits, technical measures + control obligations

Question 15

Ecosystem-based management

Answer 15

overall objective = to sustain healthy marine ecosystems + fisheries they support. in particular:
(i) avoid degradation of ecosystems, as measured by indicators of environmental quality + system status
(ii) minimise risk of irreversible change to natural assemblages of spp + ecosystem procsses
(iii) obtain + maintain l-t socioeconomic benefits w/o compromising the ecosystem
(iv) generate knowledge of ecosystem processes sufficient to understand the likely consequences of human actions

differs from management based around single (or even mixed) spp

fishery could be considered overfished within the ecosystem plan (ecosystem overfishing) when it is not overfished in a single- spp context

e.g. i. if a forage spp that serves as a prey resource for marine predators = also the target of a fishery; ii. when overfishing of large predators causes food web shifts

Question 16

Marine reserves

Answer 16

Marine Reserves, Marine Protected Areas (MPAs, No-Take Zones…)

fish biomass exported from MPA based on two hypothesised processes:
1. enhanced spawning stock biomass (v difficult to conclusively demonstrate)
2. Export of adult fish to areas open to fishing through spillover; either density-independent or density-dependent movements

need control or likely not effective