Autumn tops abalone weigh-in

The desire to target Greenlip Abalone at their peak weight could lead to significant changes in the timing of harvest for the South Australian fishery, benefiting both abalone populations and fishers

Abalone diver Darryl Carrison processing Greenlip Abalone.

By Catherine Norwood

South Australia’s wild Greenlip Abalone (Haliotis laevigata) reach their peak weight in autumn, specifically April and May. For divers, this means less time and effort to harvest their allocated quota. Harvesting larger Greenlip Abalone also increases the overall value of their harvest, even with a smaller number of abalone in the bag.

This is the finding of research initiated by the SA abalone industry, keen to improve the profitability of the fishery while preserving its sustainability. These are also key goals of Primary Industries and Regions South Australia, the government body responsible for the sustainable management of abalone fisheries in SA.

Marine scientist Ben Stobart from the South Australian Research and Development Institute (SARDI) presented the research findings during the combined Australian and New Zealand abalone industry convention in New Zealand recently. He says local divers were generally aware that Greenlip Abalone weighed more in the cooler months and were keen to quantify what this might mean for the fishery.  
January and February have traditionally been the busiest period across the state, in the lead up to Chinese New Year, when abalone is in high demand as a luxury, celebratory item. From the opening of the quota period on 1 January, about half of the year’s total catch has previously been harvested by mid February, and 80 per cent by the end of April.

However, 95 per cent of SA’s Greenlip Abalone is exported frozen, so the timing of harvest makes little difference from a marketing perspective.

Ben Stobart says the research (Table 1) found that a larger autumn harvest, in conjunction with the current weight-based total allowable commercial catch (TACC) of 69 tonnes bled-meat weight, could increase the fishery value by 1.3 per cent or almost $110,000.

This would largely be due to catching more Grade 1 abalone in April and May. It would also leave 13 per cent more Greenlip Abalone in the water – about 36,000 animals.

Autumn harvesting with an increase in the TACC to allow the same number of individual Greenlip Abalone to be harvested could increase the fishery’s value by more than 10 per cent,
or $1 million.

The research identified several other potential benefits from later harvesting. These included allowing more Greenlip Abalone to complete their spawning, which extends from October to January.

Harvesting more Greenlip Abalone allows fishers to reach their quota weight with a smaller number of higher-grade animals.
Photos: SARDI

By maintaining the current TACC, an additional 36,000 abalone would also be retained to spawn – potentially another 61 billion eggs a year to protect the sustainability of the fishery. The additional Greenlip Abalone in the fishery would have more time to grow larger, increasing the percentage of Grade 1 abalone in future years.

The collective result for the fishery could improve overall profitability, as catch per unit of effort (CPUE) and incomes increased, as a result of harvesting higher-grade abalone.

Vice-president of the SA Abalone Industry Association Bill Ford says changes to the timing of harvest are gradually being introduced in the western zone of the Greenlip Abalone fishery, from Franklin Harbour to the Western Australian border, which was the focus area of the research. A cap of 15 per cent of quota in January and 15 per cent in February was
introduced in 2014.

“This will allow us to leave more abalone in the water,” Bill Ford says. “Industry has agreed with the state government on the cap, to make sure everyone is operating on the same basis. At this stage we’re implementing the changes a little at a time and we’ll see how it goes.”

Bill Ford says a similar project is planned for Blacklip Abalone (Haliotis rubra) next year.

Table 1 Modelled changes to income and abalone harvested as a result of changes to harvest timing in the South Australian Greenlip Abalone Western Zone.
 % of quota harvested by month
 
Month
 Scenario Number
 

1 2 3 4 5 6 7 8 9 10
January
50 39 8.3 33            
Feburary
14
11 8.3              
March
10 6 8.3 7.6 17 14        
April 7 13 8.3 22 21 29  50 10    
May
4 1 8.3 22 21 29  50 20 10  
June
4 6 8.3 7.6 8.2 14   30 20  
July
2 3 8.3 7.6 8.2 14   30 20  
August
3 4 8.3   8.2     10 20
10
September 3 2 8.3   8.2       20 15
October 3 6 8.3   8.2       10 20
November
1   8.3             25
December
 1   8.3             30
 Harvest Strategy 1: Tacc 69 Tonnes Bled-Meat Weight
Number of abalone harvested to reach TACC 277,481 271,501 276,128 259,833 255,522 244,155 241,308 247,646 265,610 313,080
Revenue $8,282,749 $8,297,583 $8,272,010 $8,333,701 $8,333,176 $8,373,044 $8,382,358 $8,358,657 $8,295,188 $8,152,976
Change in revenue compared to Scenario 1   $14,834 -$10,739 $50,952 $50,427 $90,296 $99,609 $75,908 $12,440  -$129,773
 Harvest strategy 2: TACC approx. 277,481 animals
Revenue  $8,282,749 $8,480,331 $8,312,543 $8,898,033 $9,049,308 $9,515,942 $9,638,910 $9,365,642 $8,665,934 $7,225,943
Change in revenue compared to Scenario 1   $197,582 $29,794 $615,285 $766,559 $1,233,193 $1,356,161 $1,082,893 $383,186 -$1,056,806

The research analysed 10 different harvest timings under the current total allowable commercial catch (TACC) by weight and with an increased TACC that maintained the current number of abalone harvested. Scenario 1 represented the fishing pattern between 2005 and 2009. Scenario 2 represented the more delayed 2011 harvest pattern. The other eight fictional scenarios provide a range of timings for comparison of abalone yield and financial returns.

FRDC Research Code: 2010-013