Authorisation of marine fish farms in Scottish waters: locational guidelines

The following tables and maps describe the Category 1, 2 and 3 areas for the Scottish Government Locational Guidelines, designated on the basis of MSS predictive modelling to estimate nutrient enhancement and benthic impact in sea lochs or similar water bodies supporting aquaculture.

For a detailed explanation of how these categorisations were derived, refer to the Scottish Fisheries Research Report ‘Scottish Government Locational Guidelines for fish farming: Predicted levels of nutrient enhancement and benthic impact’. Predictive models were used to assign each sea loch an index of ‘nutrient enhancement’ and ‘benthic impact’.

The sum of these indices was used for the categorisation of areas as indicated below.

Combined 'nutrient enhancement' and 'benthic impact' indices	Category
7 – 10	1
5 – 6	2
0 – 4	3

These tables and maps were last updated in March 2024. Maps are available on the Marine Scotland website. The next update will be June 2024.

Please note that the Sealoch parameters used in the MSS Locational Guidelines predictive models for the calculation of the sea loch categories can now be found at the end of this document.

Category 1 areas

For 'Maximum biomass (tonnes)', biomasss is as consented by SEPA at time of modelling, taking into consideration grouped and rotational sites.

For 'Total biomass (tonnes)', biomass is as consented by SEPA at the time of modelling on a site-by site-basis.

	Loch	Maximum biomass (tonnes)†	Total biomass (tonnes)#	‘Nutrient enhancement’ index	‘Benthic impact’ index	‘Combined’ index
1	Loch Airdbhair (inc Loch na Droigniche)	375	375	3	4	7
2	Calbha Bay	1080	1080	4	3	7
3	Loch Meanervagh	433	433	4	4	8
4	Northra Voe	500	500	4	3	7
5	Sandsound Voe	5136	5136	4	3	7
6	Loch Sheilavaig	1211	2111	4	4	8
7	Stromness Voe	1650	1650	4	3	7
8	Vaila Sound	3595	3595	4	3	7
9	Vidlin Voe	2846	2846	4	3	7
10	Weisdale Voe	3952	3952	4	3	7

† Biomass as consented by SEPA at time of modelling, taking into consideration grouped and rotational sites.

# Biomass as consented by SEPA at the time of modelling on a site by site basis.

Category 2 areas

For 'Maximum biomass (tonnes)', biomasss is as consented by SEPA at time of modelling, taking into consideration grouped and rotational sites.

For 'Total biomass (tonnes)', biomass is as consented by SEPA at the time of modelling on a site-by site-basis.

	Loch	Maximum biomass (tonnes)	Total biomass (tonnes)	‘Nutrient enhancement’ index	‘Benthic impact’ index	‘Combined’ index
1	A’Choire	1400	1400	3	3	6
2	Loch Ainort	1800	1800	2	3	5
3	Aith Voe	3484	3484	3	2	5
4	Loch A’Laip	750	750	3	3	6
5	Badcall Bay	1007	1607	3	3	6
6	Baltasound	2185	2185	3	2	5
7	Basta Voe	4461	4461	3	3	6
8	Loch Boisdale	4071	4071	3	3	6
9	Brindister Voe / Vementry Sound	2166	2166	3	2	5
10	Busta Voe	1050	1050	3	2	5
11	Loch Carnan	410	410	3	3	6
12	Cat Firth	1343	1343	3	2	5
13	Loch Clash	540	540	2	3	5
14	Clift Sound	4982	4982	3	3	6
15	Dales Voe North	850	850	3	2	5
16	Dury Voe	5460	5460	3	2	5
17	East  Loch Tarbert	13212	13212	2	3	5
18	Loch Eport	1589	1589	2	3	5
19	Loch Erisort / Leurbost	8777	8777	2	3	5
20	Loch Greshornish	2195	2195	2	3	5
21	Loch Grimshader	622	622	3	3	6
22	Loch Grosebay	2001	2001	3	3	6
23	Gruting Voe	4395	4395	4	2	6
24	Loch Harport	2000	2000	2	3	5
25	Loch Kishorn	3500	4799	2	3	5
26	Loch Laxfirth	942	942	3	2	5
27	Mid Yell Voe	1210	1210	3	3	6
28	Loch Nedd	250	250	2	3	5
29	Loch Odhairn	2801	2801	3	3	6
30	Olna Voe	2500	2500	3	3	6
31	Loch Pooltiel	2700	2700	3	2	5
32	Loch Portree	4214	4214	3	3	6
33	Ronas Voe	2350	2350	3	2	5
34	Loch Seaforth	7380	7380	2	3	5
35	Loch Shell	6453	6453	2	3	5
36	Loch Skiport	2460	2460	3	3	6
37	Swarbacks Minn	19842	20342	3	3	6
38	Swining Voe	1920	1920	3	2	5
39	Swinister Voe	13227	13227	3	3	6
40	Uig Bay	1625	1625	3	3	6
41	Loch Uiskevagh	1104	1104	3	3	6
42	Wadbister Voe	800	800	3	2	5

Category 3 areas

	Loch	Maximum biomass (tonnes)†	Total biomass (tonnes)#	‘Nutrient enhancement’ index	‘Benthic impact’ index	‘Combined’ index
1	Loch Ailort	300	300	1	1	2
2	Loch Aline	0	0	0	0	0
3	Loch Alsh (inc Loch Long)	5600	5600	2	2	4
4	Loch Arnish	0	0	0	0	0
5	Loch Bay	500	500	1	1	2
6	Loch Bracadale	2075	2075	1	1	2
7	Broad Bay	2240	2240	1	1	2
8	Loch Broom	1050	1050	1	1	2
9	Burwick Bay	0	0	0	0	0
10	Loch Cairnbhain (inc. Loch Glendhu and Loch Glencoul)	3350	3350	2	2	4
11	Loch Caolisport	192	192	1	1	2
12	Loch Carron	2687	2687	1	2	3
13	Loch Claidh	0	0	0	0	0
14	Collafirth Voe	0	0	0	0	0
15	Loch Craignish	3183	3183	2	2	4
16	Loch Creran	3000	3000	2	2	4
17	Dales Voe	0	0	0	0	0
18	Loch Duich	2500	2500	2	2	4
19	Loch Dunvegan	5945	5945	2	2	4
20	Loch Eishort	1200	1200	2	2	4
21	Loch Eriboll	1395	1395	1	1	2
22	Loch Etive	4004	4004	2	2	4
23	Loch Ewe	1	1	1	0	1
24	Loch Eynort	20	20	1	1	2
25	Loch Feochan	0	0	0	0	0
26	Loch Fyne	13557	13557	1	2	3
27	Loch Geocrab	200	200	2	2	4
28	Loch Hourn	3625	3625	1	2	3
29	Loch Inchard	0	0	0	0	0
30	Loch Kilerivagh	0	0	0	0	0
31	Kirk Hope	0	0	0	0	0
32	Loch Laxford	1390	2026	2	2	4
33	Loch Leven	1607	1607	2	2	4
34	Loch Linnhe (inc.Loch Eil)	5000	5000	1	2	3
35	Little Loch Broom	1997	1997	1	2	3
36	Loch Long (inc. Loch Goil)	4522	4522	1	1	2
37	Loch Melfort	615	615	1	1	2
38	Loch Mharabhig	0	0	0	0	0
39	Loch Moidart	0	0	0	0	0
40	Loch na Keal	2770	2770	1	2	3
41	Loch Nevis	4480	4480	1	2	3
42	Pierowall Bay	165	165	2	2	4
43	Loch Riddon	0	0	0	0	0
44	Loch Roag	15739	15739	2	2	4
45	Loch Ryan	0	0	0	0	0
46	Loch Scridain	1900	1900	1	1	2
47	Selivoe	963	963	3	1	4
48	Loch Slapin	350	350	1	2	3
49	Loch Sligachan	0	0	0	0	0
50	Loch Snizort Beag	500	500	1	2	3
51	Loch Spelve	1578	1578	2	1	3
52	Loch Stockinish	0	0	0	0	0
53	Loch Striven	4673	4673	2	2	4
54	Loch Sunart	5680	5680	1	2	3
55	Loch Sween	0	0	0	0	0
56	Tobermory Bay	0	0	0	0	0
57	Loch Torridon	7685	7685	1	2	3
58	Loch Tuath	2572	2572	1	2	3
59	West Burra Firth	0	0	0	0	0
60	West  Loch Tarbert	4658	4658	2	2	4
61	Whalefirth Voe	813	813	2	2	4
62	Whiteness Voe	500	500	3	1	4

# Biomass as consented by SEPA at the time of modelling on a site by site basis

Prevous reports are in our website archive.

Sealoch parameters* used in the MSS Locational Guidelines predictive models

* The majority of these parameters have been taken from Edwards and Sharples (1986), however the volumes and areas were re-calculated in 2006 by digitising the depth contours on Admiralty charts.

Loch name	Length (km)	Area (km squared)	Volume (mm cubed))	Tidal range (m)	Tf (days)	Q (Mm cubed 3 year-1)
A’Choire	2.3	1.3	17.1	3.4	3.0	2077
Ailort	8.1	8.7	91.3	4.3	1.9	17542
Ainort	3.9	3.5	52.5	4.6	2.5	7665
Airdbhair	2.2	0.4	2.1	4.2	0.9	839
Aith Hope	1.8	0.6	3.0	2.3	1.7	644
AIith Voe	4.0	4.8	117.7	1.7	10.7	4015
A’Laip	2.5	1.1	5.7	3.9	1.0	2072
Aline	3.5	1.8	17.5	3.4	2.2	2903
Alsh	13.1	27.2	933.9	4.6	5.6	60873
Arnish	2.0	2.0	61.1	3.2	7.2	3097
Badcall Bay	1.9	1.3	13.9	3.6	2.3	2208
Baltasound	2.9	3.7	30.5	1.9	3.3	3375
Basta Voe	5.2	5.7	75.5	1.9	5.2	5298
Bay	6.9	15.4	343.0	4.5	3.7	33837
Boisdale	5.7	4.7	55.1	3.8	2.3	8749
Bracadale	10.5	45.8	1053.9	3.1	5.6	68693
Brindister	5.5	5.0	46.2	1.7	4.1	4112
Broad Bay	14.0	82.5	1357.7	4.1	3.0	165188
Broom	14.7	16.0	391.6	4.5	4.1	34864
Burswick	0.9	0.4	4.4	0.9	8.5	189
BUSTA	3.0	3.0	50.7	1.7	7.3	2537
Cairnbhain	14.9	14.0	330.6	4.2	4.2	28727
Calbha Bay	1.4	0.7	8.2	3.6	2.6	1153
Caolisport	8.3	14.9	163.4	0.9	9.1	6552
Carnan	1.8	0.7	2.1	3.9	0.6	1294
Carron	26.7	20.6	602.5	4.7	4.7	46791
Cat Firth	3.0	2.8	26.9	1.8	4.1	2395
Claidh	6.7	4.5	97.6	4.2	3.9	9134
Clash	1.6	1.0	17.2	4.2	3.0	2096
Clift Soundf	10.0	8.5	123.6	1.4	7.8	5782
Collafirth	2.4	0.9	11.5	1.8	5.1	820
Craignish	8.8	14.6	202.0	2.1	5.0	14750
Creran	12.8	12.4	161.1	3.3	3.0	19600
Dales Voe	4.9	3.2	47.3	1.2	9.2	1877
Dales Voe North	5.1	3.1	48.2	1.8	6.4	2751
Duich	8.3	11.2	510.7	4.6	7.4	25191
Dunvegan	10.4	21.7	1255.5	4.5	9.6	47736
Dury Voe	6.5	13.0	308.5	1.4	13.1	8597
East Loch Tarbert	8.5	26.2	518.5	4.2	3.6	52575
Eishort	5.2	2.5	19.4	4.3	1.4	5045
Eport	7.0	3.9	27.4	4.1	1.3	7695
Eriboll	15.5	37.5	954.1	4.3	4.4	79150
Erisort/Leurbost	14.6	15.8	227.0	4.1	2.6	31873
Etive	29.5	28.3	948.7	1.8	13.9	24913
Ewe	11.9	43.0	846.3	4.4	3.4	90853
Eynort	4.3	2.2	17.3	4.1	1.4	4502
Feochan	6.7	2.8	17.9	3.3	1.5	4356
Fyne	60.5	183.3	9440.2	3.1	12.4	277876
Geocrab	2.5	0.6	5.4	4.2	1.6	1227
Greshornish	5.9	4.7	74.1	4.6	2.6	10403
Grimshader	3.5	0.9	8.4	4.1	1.7	1806
Grosebay	2.6	2.9	47.9	4.2	2.9	6025
Gruting	7.6	6.7	95.7	1.1	9.7	3600
Harport	12.5	7.2	108.8	4.3	2.7	14710
Hourn	21.3	34.5	1905.0	4.2	9.8	70953
Inchard	6.6	3.7	77.1	4.2	3.7	7608
Kilerivach	4.2	1.0	2.2	3.9	0.5	1606
Kirk Hope	1.8	0.6	4.4	2.3	2.4	669
Kishorn	4.1	7.8	191.3	4.7	3.9	17901
Laxfirth	3.8	2.3	21.1	1.8	3.9	1977
Laxford	7.0	7.2	107.5	4.2	2.7	14528
Leven	13.4	8.1	149.2	3.7	3.8	14335
Linnhe	29.1	33.7	1303.7	3.7	7.8	61006
Little L Broom	12.7	23.0	914.7	4.5	6.6	50587
Long	26.9	44.0	1758.0	3.1	9.6	66840
Meanervach	1.4	0.2	0.8	3.9	0.9	315
Melfort	6.0	10.2	256.5	2.3	8.2	11418
Mharabhig	1.3	0.5	1.7	4.1	0.7	864
Mid Yell	3.3	1.7	11.7	1.9	2.7	1576
Moidart	2.8	2.9	8.6	4.3	0.6	5232
Na Keal	10.7	32.2	694.7	3.8	4.3	58966
Nedd	2.4	0.5	3.3	4.2	1.1	1110
Nevis	17.2	29.9	1505.0	4.3	8.8	62424
Northra Voe	1.0	0.3	2.2	1.5	4.2	187
Odhairn	3.6	1.8	29.8	4.1	3.1	3511
OlnaVoe	4.6	4.0	79.6	1.7	8.7	3341
Pierowall Harbour	1.6	1.1	3.5	2.3	1.0	1286
Pool Tiel	3.9	3.9	111.4	3.1	7.0	5808
Portree	4.9	4.1	88.3	4.6	3.5	9212
Riddon	5.3	2.8	49.8	2.6	5.1	3561
Roag	14.0	68.3	1135.5	3.6	3.5	118419
Ronas Voe	9.4	9.4	176.0	1.7	8.2	7834
Ryan	13.4	36.6	166.4	2.8	1.3	46720
Sandsound	8.6	6.0	69.7	1.1	7.9	3219
Scridain	12.0	27.0	734.2	3.7	5.5	48721
Seaforth	22.6	24.6	604.1	4.2	4.4	50111
Selivoe	4.0	4.8	88.9	1.1	12.5	2597
Sheilavaig	3.0	0.6	1.5	4.1	0.5	1105
Shell	7.5	15.0	391.5	4.1	4.8	29769
Skiport	4.6	3.0	38.9	4.1	2.4	5919
Slapin	3.4	2.1	11.6	4.3	1.0	4219
Sligachan	4.4	1.7	15.7	4.6	1.5	3809
Snizort Beg	4.7	6.9	101.9	4.6	2.5	14884
Spelve	7.7	8.9	144.9	3.5	3.5	15111
Stockinish	3.5	1.5	17.8	4.2	2.1	3093
Striven	12.9	14.3	546.7	2.6	11.0	18142
StromnessVoe	4.6	2.3	13.6	1.1	4.1	1209
Sunart	30.7	50.6	1754.0	4.0	6.5	98493
Swarbacks Minn	13.0	30.9	995.1	1.7	14.1	25759
Sween	14.8	17.4	216.9	1.6	5.9	13418
Swining Voe	4.0	3.5	63.1	1.8	7.6	3031
Swinster Voe	6.3	14.9	367.5	1.8	4.9	27377
Tobermory Bay	1.6	1.6	36.6	3.7	4.7	2842
Torridon	22.2	68.5	3300.2	4.9	7.4	162779
Tuath	9.5	23.4	412.4	3.5	3.8	39616
Uig Bay	8.8	3.1	64.8	3.1	5.1	4639
Uiskevagh	3.3	1.9	10.0	4.1	1.0	3652
Vaila Sound	3.5	3.6	35.6	1.2	6.1	2128
Vidlin Voe	3.0	2.7	37.3	1.8	5.7	2392
Wadbister Voe	2.1	1.6	18.2	1.8	4.7	1416
Weisdale	6.7	6.0	104.0	1.1	11.7	3244
West Burra Firth	1.6	0.9	10.4	1.3	6.7	567
West Loch Tarbert	6.5	23.2	396.9	3.8	3.4	42614
Whalefirth	6.3	3.1	28.0	1.9	3.6	2839
Whiteness Voe	4.5	3.0	36.0	1.1	8.3	1583

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Locational guidelines for the authorisation of marine fish farms in Scottish waters

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