Purse Seining

Question 1

How much does purse seining contribute to global catches?

Answer 1

30% of global catch

Question 2

What is purse seining used to catch?

Answer 2

Dense mobile pelagic species
-Important to catch bulk of whiting (converted to fish meal for animal feeds)
-Species with high individual value, tuna

Question 3

In Northern Europe (Mainly Scotland and Norway) what do pursers target?

Answer 3

-Mackerel
-Herring
-Scad

Question 4

What do pursers catch in the Mediterranean?

Answer 4

-Sardines
-Anchovy
-Tuna

Question 5

What are the advantages of purse seining?

Answer 5

-Capable of catching tonnes of fish in one haul
-Most efficient method of catching dense shoals of fish

Question 6

What does purse seining success depends on?

Answer 6

-Fish being near surface
-Fine calm weather conditions

Question 7

What do pursers target in tropical waters?

Answer 7

Tuna
(French and Spanish)

Question 8

How long can ocean going seines be?

Answer 8

Over 100 m long

Question 9

Describe the purse seine net

Answer 9

-Wall of vertical net fencing
-Size adapted to suit vessel size and target species
-Mesh size to suit target species

Question 10

How big are purse seine nets?

Answer 10

200 - 400 m long
60 - 90 m deep

Question 11

What is the function of headropes?

Answer 11

Carries numerous floats to keep net on the surface

Question 12

Describe the physical structure of the purse seine net

Answer 12

-Lower frame rope of net is equipped with a lead line and rings (purse rings) through which a special cable (purse wire) is passed

Question 13

What is the function of the purse wire?

Answer 13

Closes off the bottom of the net and prevents fish from escaping downwards

Question 14

What are stages 1-6 using a purse seine net?

Answer 14

1. Vessel acquires target shoal on sonar
2. Launch a buoy or skiff that carries a wing of the net as the vessels encircles the shoal
3. Encirclement complete, net deploys to depth
   4.Pursing commences, preventing escape of fish
   5.Shoal brought to vessels side ready for brailing
4. With net dried up, vessel is ready for next shot

Question 15

What do sardines do when panicked?

Answer 15

Similar to behaviours of adult herring
-When panicked, they sound (dives to the bottom)

Question 16

What does the term the net is dried mean?

Answer 16

It is progressively brought on board, reducing the portion in the water that contains fish to a minimum

Question 17

What is a blunt in regards to purse seining?

Answer 17

Is the portion of the seine net still in the water after drying that is a concentrated pocket of fish

Question 18

What is the function of brailers / fish pumps

Answer 18

Brailers - smaller meshed nets
Function of both is transport fish from the seine to the boat

Question 19

Describe purse seiners (vessels)

Answer 19

-Built to steam faster to reach markets as quick as possible
-Stores catch in RSW tanks to ensure good quality
-New seiners are more versatile- can pelagic trawl and purse to cope with changing patterns of fish

Question 20

What does FAD stand for?

Answer 20

Fish Aggregating Device

Question 21

What is a Fish Aggregating Device?

Answer 21

Manmade floating / suspended structures

Question 22

Why are FADs effective?

Answer 22

Various species of fish congregate or associate with floating objects in the sea

Question 23

What are some major disadvantages of purse seining?

Answer 23

-Mostly small fish swim at surface
-High mortality of target species
-By-catch mortality
-Poor monitoring of fleets
-High costs

Question 24

What are by-catch species of purse seining?

Answer 24

-Juvenile fish
-Megafuana
-Young bigeye and yellowfin tuna
-Sharks
-Rays
-Turtles
-Spotted and spinner dolphins (Eastern tropical Pacific)

Question 25

How much of the world’s tuna catch is from purse seining?

Answer 25

75%

Question 26

What is an issue with purse seining for skipjack tuna?

Answer 26

Skipjack tuna shoal together with young bigeye and yellowfin tuna
-Immature fish are harvested with goes against the whole principle of fisheries management