Did some digging, this is what i came up with in terms of Leases...

Did some digging, this is what i came up with in terms of Leases and Zones that Tassal operate in the 5 areas.
MFDP = Marine Farm Development Plan
MLA = Maximum Leasable Area
While Macquarie is significant, its not 'make or break', the Franklin lease that is destocked is about 10% of MLA, the 'West of Wedge' proposed development could be interesting as its more deep water than any other leases, there might be some risk/reward in pushing out, im not sure.
(EDIT: and of course, this is to the best of my knowledge, i could easily have made mistakes)

	Column 1	Column 2	Column 3	Column 4	Column 5	Column 6	Column 7
1	MFDP	Marine Farm Lease No	Lease Name	Zone	Zone Name	Area (H)	MLA (H)
2	Macquarie Harbour	214	Middle Harbour	7	Liberty Point Central Harbour	100	80.00
3	Macquarie Harbour	219	Gordon	8	South Central Harbour	100	80.00
4	Macquarie Harbour	266	Franklin	9	North-east of Bryans Bay	190.4	120.00
5	D’Entrecasteaux Channel	185	Great Taylors Bay	18A	Tin Pot Point	442.91	150.00
6	D’Entrecasteaux Channel	203	Great Taylors Bay	18A	Partridge Island	442.91	150.00
7	D’Entrecasteaux Channel	109	Great Taylors Bay	18B	Butlers Point	106.70	28.50
8	D’Entrecasteaux Channel	78	Lippies Point	25	East of Lippies	411.00	76.51
9	Huon River and Port Esperance	186	Huon River	3	Brabazon Point	21.19	12.50
10	Huon River and Port Esperance	189	Huon River	5	Killala Bay	22.39	12.00
11	Tasman Peninsula and Norfolk Bay	190	Nubeena	14A	Creases Mistake	143.10	48.50
12	Tasman Peninsula and Norfolk Bay	194	Nubeena	14B	Billy Blue	3.95	3.00
13	Tasman Peninsula and Norfolk Bay	193	Nubeena	14D	Badger Cove	0.45	0.43
14	Tasman Peninsula and Norfolk Bay	55	Long Bay	15B	Port Arthur		15.01
15	Tasman Peninsula and Norfolk Bay	Proposed	West of Wedge	Proposed			180.00
16	Great Oyster Bay and Mercury Passage			4	Okehampton Bay	203.5	100.00
17							1056.45