Scottish Marine and Freshwater Science Volume 5 Number 17: ScotMap Inshore Fisheries Mapping in Scotland: Recording Fishermen's use of the Sea

5. Mapped Outputs

Examples of the maps produced from data collected during the study, aggregated according to the gear species combinations in Figure 1 and maps for the combined ScotMap data set are provided below.

Pots: All crab and lobster species.

Figure 5: Vessel number (a) and monetary value distribution (b) for creel (pot) fishing for crab and lobster all species. From polygons identifying crab and/or lobster (brown crab and/or velvet crab, green crab, spider /spiny crab, common lobster, crawfish, squat lobster) as the primary or secondary target species where the fishing gear is pots.

The map of aggregated raster data of vessel number for creel (pot) fishing for crab and lobster all species (Figure 5a) indicates that these fisheries are prosecuted around almost all of Scotland. Vessel activity is concentrated inshore with distinct foci around the Orkney Isles and the Pentland Firth, along the Moray Firth coastline, the east coast and around the Outer Hebrides, on both western and eastern seaboards. Fisheries associated with smaller islands, e.g. Tiree, are also evident. Relatively little activity was mapped in the Clyde Sea area or the Solway Firth. A similar distribution is indicated by the monetary value map (Figure 5b). The areas of highest value are often inshore, in areas where the lobster is an important target species. Brown crab is the main target species in the more extensive offshore areas evident on both the value and activity maps.

Pots: Nephrops .

Figure 6: Vessel number (a) and monetary value distribution (b) for Nephrops creel (pots) fishing.

Maps of the Nephrops creel fishing vessel activity and value (Figure 6a and b) show an almost exclusively west coast distribution. Activity and value are concentrated to the east of the Outer Hebrides extending into both the North and South Minch, around Skye, in the sea lochs along the north west coast and the Inner Sound of Raasay. The mapping also indicates important Nephrops creel fishing areas further south, around Mull and Jura and smaller high value areas to the north of Islay and in the sea lochs of the Clyde.

Trawl: Nephrops.

Figure 7: Vessel number (a) and monetary value distribution (b) for Nephrops trawling.

The vessel number and value maps of trawl fishing for Nephrops (Figure 7a and b) show fisheries off both the east and west coasts of Scotland, with a generally more offshore distribution than those of creels. There are significant concentrations of activity in the Moray Firth, the Firth of Forth and extensive areas in the North and South Minch, with areas of particularly high activity and/or value around Skye, Rum and Eigg and North of Raasay.

Trawl: Species excluding Nephrops.

Figure 8: Vessel number (a) and monetary value distribution (b) of vessels deploying trawl as fishing gear with various target species. Includes common squid predominant target species, as well as haddock, plaice and other flatfish.

The majority of fishing mapped in Figure 8 represents fisheries targeting squid. These are located in the Moray Firth and the Firth of Forth and prosecuted on a seasonal basis often by vessels which fish for Nephrops at other times of year. Some fishing areas for demersal fin fish species, including haddock and flatfish were identified, but these were few and are included in this category rather than being mapped separately. They are represented by some of the larger offshore extents, but some squid fishing is similarly mapped relatively far offshore.

Towed Dredges: King scallop.

Figure 9: Vessel number (a) and monetary value distribution (b) for king scallop fishing using towed dredges.

Maps of vessel number for towed dredge fishing targeting king scallop (Figure 9a) indicated relatively few vessels fishing over extensive areas in the Moray Firth, off the east coast of Scotland and the inter-island areas of the Minches, with foci of activity to the east of the Orkney Isles and south west of Islay. The monetary value map (Figure 9b) showed relatively high value areas to the east of Orkney and in south west Scotland (Luce Bay) and also an area close inshore on the eastern seaboard of the Outer Hebrides. The value map gives a better impression of extent of the fishery and the importance of different areas than that for vessel number, particularly in the south west, around Islay, Jura and in the Clyde Sea.

Dive (hand): King scallop

Figure 10: Vessel number (a1 & a2) and monetary value distribution (b1 & b2) king scallop diving.

The landings value for scallop dive vessels (Figure 10b1 and b2) shows an inshore distribution which presumably reflects constraints on divers' working depth. The fishery is evidently very important in the Orkney Islands (Figure 10 a1 and b1) and along the coast from the Sound of Islay to the Mull of Kintyre (Figure 10 a2 and b2). There are also small foci of value in the Clyde Sea and Luce Bay.

Lines: Mackerel

Figure 11: Vessel number (a) and monetary value distribution (b) for mackerel line fisheries.

Vessel number and value for the mackerel line fisheries (Figure 11) map very closely. The most important areas are located on the east coast, particularly around Fraserburgh and Peterhead and off the Nook of Fife.

Aggregated Data (All Interviews Combined)

Aggregated raster data for all the vessels interviewed for ScotMap for vessel number, crew number, monetary value and relative value are mapped in Figure 12 to Figure 15.

Figure 12: Distribution of the number of vessels from all interviewed vessels.

Vessel number (Figure 12) indicates that under 15 m vessels fish all around the coasts of Scotland, and in some cases more than 12 nautical miles ( NM) from the coast. The main foci of activity ( i.e. extensive areas with relatively high numbers of vessels per cell) are along the north coast of the Moray Firth, the Firth of Forth and in the North and South Minch particularly around Skye. In most areas activity tends to be concentrated within 6 NM of the coast but there areas where intermediate levels of vessel activity extend further offshore e.g. in the North Minch and the Moray Firth.

Figure 13: Distribution of the number of crew from all interviewed vessels.

There is a close spatial correlation between the number of vessels and the number of employees (Figure 13). This is to be expected as the number of employees per cell is essentially a function of number of vessels. The average number of crew recorded for smaller vessels (<10 m), is typically one or two as compared with anything between three and five on larger (> 10 m) trawlers and dredges and scallop dive vessels.

Figure 14: Distribution of monetary value from all interviewed vessels.

On the aggregated value map, data from all interviews combined (Figure 14), the highest value areas are generally within 3 NM of the coast. The distribution of value, classified on a national scale, reflects the distribution of fisheries for high value species e.g. lobster and creel caught Nephrops, areas of high vessel activity and, in some cases, relatively small areas where the larger, higher earning vessels fish. The aggregated value map provides useful synoptic information but is probably best interpreted in conjunction with the fisheries breakdowns (above) particularly if working in a regional context. It should be emphasised that the data are likely to under-represent value in regions where a high proportion of interviewees declined to give earnings information or where interview coverage was poor.

Figure 15: Distribution of relative value from all interviewed vessels.

The map of relative value (Figure 15) provides an alternative representation of the importance of fishing. Because it is based on the percentage contribution sea areas make to vessel earnings, rather than the absolute value, it is less influenced by species value or high earning vessels. Areas of highest relative value are, in general, those where there are numerous overlapping polygon extents or areas where there are intermediate numbers of small polygons ( e.g. with extents comparable to the size of a cell). All of the highest relative value cells map close inshore, within 3 NM. This reflects the distribution of creel fishing, its representation in the interview sample and its predominantly inshore distribution. Relative value can be a useful indicator of sea areas of particular importance to remote communities, e.g. north of Kirkwall and around Westray and North Ronaldsay, which are less evident on a value map. Relative value is also robust to missing earnings data. In this study it is a better indicator of the important creel fishing areas on the north coast of the Moray Firth than the value map.

Aggregated data outputs from ScotMap are available on Marine Scotland Interactive (MSi) and National Marine Plan Interactive (NMPi) websites as pdf maps and downloadable raster data sets.