Lecture 29- Australian Fisheries

Question 1

How have fisheries increase in the last 40 years?

Answer 1

-4x in the last 40 years

Question 2

How do Australian fisheries compare to other countries?

Answer 2

-small
-the Australian fishing zone is one of the world’s largest in the world
-includes: Antarctica, Macquire and Heard Islands, Christmas and Cocos Keeling Islands, Lord Howe and Norfolk Islands
-Huge fishing zone: 3rd largest in the world Low productivity – no major upwelling zones • ranks 60th in world in commercial catch
• 0.2% of world’s total catch
High diversity (many different species) and high value
• 2% of world value
• Major fisheries: Prawn, Rock Lobster, Tuna, Salmon,
Abalone
-Fisheries are 5th most valuable food industry in Australia

Question 3

What is the Australian Fisheries Management Authority?

Answer 3

• “Responsible for the efficient and sustainable management of Commonwealth fish resources on behalf of the Australian community.”
• Ranked no. 2 in the world for sustainability
• Ways fisheries are managed:
• effort controls (gear type restrictions, seasonal closures) • output controls (quotas, size limits, bag limits)
• habitat protection zones (marine parks, nursery grounds,
vulnerable populations)
• Australian fish stocks are generally in good shape and improving.
• Managed for sustainability - Catch levels are generally set to keep target species population levels steady…
• …and to minimise broader impacts on marine ecosystem.
• When troubles with a fishery are detected, catch limits
and other management strategies are set in place.
• Major issue is lack of adequate knowledge on some fisheries

Question 4

Has the aquaculture grown in the last past years?

Answer 4

• yes
• substantially
• it is rising year by year in Australia

Question 5

What are the top 5 species groups (in terms of production value) in aquaculture?

Answer 5

• salmonids
• tuna
• pearl oysters
• edible oysters
• prawns

Question 6

What are some other species that are aquacultured?

Answer 6

• finfish (barramundi, snapper, kingfish, Murray cod) • abalone
• mussels
• mud crabs
• sea cucumbers

Question 7

What are the benefits and drawbacks of Australian aquaculture fisheries?

Answer 7

1.Benefits:
• Potential to reduce pressure on natural populations • Potentially no by-catch or fishing impacts
• Can produce based on demand
• Quality control

2.Drawbacks:
• Artificial concentration of single species • Removal from the wild
• Input vs output
• Infrastructure

Question 8

What are some questions to ask before you buy/eat?

Answer 8

1. Is the species slow growing or long lived (over 20yrs old)?
   If a species is long lived or slow growing, it is likely to be vulnerable to overfishing (slow to reproduce).
2. Is it a deep sea species? (found below 500m)
   Deep sea species - life characteristics which make them particularly vulnerable to overfishing (ie: slow growing, long lived, late to reach sexual maturity).
3. Is it a shark or ray?
   Sharks and rays - biologically more like whales and dolphins than fish. They are slow growing, long lived and produce very few young. These characteristics make them particularly vulnerable to overfishing.

Question 9

What is the Southern Bluefin Tuna Fishery?

Answer 9

-large fishery

Question 10

What is the Southern Bluefin Tuna life cycle?

Answer 10

• Gather and spawn off North West shelf
• Larvae drik south in Leeuwin current
• Feed on zooplankton and grow rapidly
• Reach Great Australian Bight as juveniles
• Schools of juveniles caught in purse seines by SA fishermen
• Adult fish roam the southern and south Pacific oceans
• Feed where concentraAons of fish occur
• Oken at edges of warm eddies off NSW
• Long line fishing is main fishing method used by most fishers,
except Australian fishers

Question 11

What is the Tuna mariculture?

Answer 11

• Catch schools of juveniles off South Australia & Western Australia
• Enclose schools in nets, tow to port
• Transfer the juveniles to big sea-pens -
‘sea cage’
• Feed them imported frozen anchovies -
famen for 3 -4 months
• Harvest when large, in perfect condition
• Good condition……
= most expensive meat in the world

Question 12

Is the Southern Bluefin Fishery sustainable?

Answer 12

• IUCN red list: critically endangered
• Classed as overfished by the Bureau of Rural Sciences
• Spawning population severely depleted
• Tuna mariculture removes juveniles before they breed
• Current catches limit probability of population rebuilding
• Takes 2 – 12 kg of wild fish (fed to tuna) to produce 1kg of sea cage tuna
=SAY NO!

Question 13

What is the rock lobster fishery like?

Answer 13

• Two major species:
• Western rock lobster (Panulirus cygnus)
• Southern rock lobster (Jasus edwardsii)
-WA fishery most valuable
• Long lived – up to 20yrs
• Have very long larval stage (phyllosoma)
• 9 – 11 months
• drik around Indian Ocean gyre
• then becomes puerulus (juvenile)
• swims back towards WA, semles on rocky reefs
• Caught in lobster pots – low impact fishing method

Question 14

Which lobster is better to buy?

Answer 14

-Western Rock Lobster is better than Southern Rock Lobster

Question 15

What is Australia’s second most valuable fishery?

Answer 15

-the prawn fisheries

Question 16

What are the problems with prawn fisheries?

Answer 16

• Huge problem with by-catch • Up to 90% non-target species • 1kg prawn ≈ 5kg by-catch
• By –catch: fish, other crustaceans, rays, sharks, turtles, marine mammals
• Solutions?
• Turtle Excluding Devices (TEDs)
• Recently made mandatory in Australia


Question 17

What to do when buying prawns?

Answer 17

• think twice when buying australian wild fishery

- -aquaculture is a better choice

Question 18

What is the Southern Shark Fishery?

Answer 18

-catching the School shark and the Gummy shark
• Both species are bottom dwellers
• Adults very long lived, mature at late age (>5yrs)
• Females are viviparous (bear live young)
• Low fecundity – few offspring/yr
• Females move inshore to give birth
• Juveniles move back to deeper waters on continental
shelf
• Gill nets set along the bottom to target large juveniles
moving offshore
• 6 inch mesh: small juveniles go through, adults bounce off.

Question 19

Is the Southern shark fishery sustainable?

Answer 19

-Main species now is Gummy shark
– populations healthy But also include School shark
– populations decimated Gummy shark = Flake is a better choice
-But Flake = “any shark”=say no

Question 20

What is the issue with the shark fin?

Answer 20

• Shark fin soup – status symbol for which demand is growing
• Huge illegal fishing problem worldwide
• At least 70 million killed each year for fin trade - Big fins worth more!
• In Australia it is legal if the carcass is also used – fuels trade
• Export 165 tonne per year – Import 10 tonne
• Extinction aker 400 million years on the planet?
• trigger collapse of ecosystems

Question 21

Where does the King George whiting live?

Answer 21

-Distributed from WA to Bass Strait and NSW Shallow waters to inner conAnental shelf. Main fishing grounds in WA, SA, and Vic

Question 22

What is the King George Whiting fishery?

Answer 22

• Grow and reproduce quickly
• Mature at early age (3 – 4 years)
• Have potenAal to produce lots of offspring (broadcast spawners)
• Juveniles found in seagrass beds (nursery habitat)
• Move to deeper water as they grow larger
• Caught in seine nets and on fishing lines
=better choice

Question 23

What are the abalone fisheries?

Answer 23

-blacklip: rocky reefs , greenlip: seagrass beds, roe’s abalone: WA shallow reefs
-all feed on algae: catch drifting pieces or eat attached algae
-Blacklip fishery in all red areas
Greenlip are fished in S.A., Tas, and W.A.
Roe’s abalone is fished in W.A.
Tas: world’s largest abalone fishery
Vic: blacklip abalone are largest, and 2nd largest abalone fishery worldwide.

Question 24

What is the abalone life cycle?

Answer 24

• Abalone larvae semle on encrusting coraline algae
• When they grow large enough to be easily seen by fish they move under rocks or into cracks, and forage at night
• When they grow large enough to escape predation, they emerge onto rocks and don’t move much

Question 25

What is the abalone fishery management?

Answer 25

• Must ensure enough eggs are produced
• Larger abalone produce more eggs (millions of eggs)
• Minimum size limit ensures abalone produce many eggs before they are caught
• Part of Victorian abalone fishery destroyed by virus released from aquaculture farm in mid 2000s

Question 26

What is the summary?

Answer 26

• Australia’s fisheries are not very productive • But many species (examples?)
• Some are very valuable (examples?)
• Most Australian fisheries are sustainably managed where knowledge available
• But most are already used fully
• New laws increasingly require ecosystem protection
• Aquaculture is becoming an important alternative to
wild caught seafood
• Consumers can reduce overfishing by choosing fish carefully