Abstract
EXECUTIVE SUMMARY
The research described in this report investigated aspects of the sustainability and environmental impacts of creel fishing for Norway lobster, Nephrops norvegicus, in Loch Torridon and the Inner Sound in northwest Scotland. Creel fishing for Norway lobster, Nephrops, is thought to be less environmentally damaging than trawling, but there was little previous empirical information on this.
In 2001, a fishery order was made by Scottish Ministers, creating zones for different fishing methods in the Torridon area, including a mobile gear exclusion zone, a creel exclusion zone, a zone closed to mobile gear for 6 months per year and a mixed gear zone. There is also an area in the Inner Sound reserved for testing underwater weapons systems, which has been closed to all fishing since 1975. Additionally, the majority of local creel fishers operating in the creel-only zone abide by an agreed set of voluntary conservation measures. The fishery order is due to be reviewed in 2006 and the present study aimed to provide information to contribute to the evaluation of the effectiveness of the creel-only zone and the voluntary conservation measures.
The creel catch of Nephrops shows strong seasonal trends that reflect the patterns of moulting and reproduction in this species. Peak female catch was observed in the early spring, following moulting and mating, with catch rates becoming low after spawning in autumn. The catch rate of males peaked around February following moulting. Of those animals caught, males were larger than females, providing a partial explanation for observed seasonal variations in catch size distribution. Spatial variations in catches and the size-distributions of constituent animals were evident both among and within fisheries. Microscale mapping of fishing effort and landings, using logbooks and GPS-linked data loggers, enabled this to be resolved in detail in some areas. There is some evidence that the management measures applied by a sector of the creel fishermen in the Torridon area has had a positive effect on the stock within this area.
Behavioral studies both in the wild and in aquaria have shown that the catchability of Nephrops by creeling is low (initial results show around 1 entry per 100 approaches). The capture process could be considered as a sequence of events, at each stage of which individual Nephrops could progress towards creel entry, or move away. The role of Nephrops behaviour at each stage of the capture process was evaluated. In addition, it appeared that inter- (crabs) and intra-specific interactions deterred Nephrops from entering a creel.
Environmental damage from creeling appears to be low. The most vulnerable species in the area appears to be the large sea pen Funiculina quadrangularis and its associated brittle star Asteronyx loveni. The density of F. quadrangularis was low in the trawl zone, but numbers of F. quadrangularis seem to be little affected by creel fishing. However, there was some evidence that creel fishing may have impacted the brittle star A. loveni. Differences in species composition of benthic epifauna between fishing zones (i.e. trawled versus creeled areas) were observed, but were probably more related to habitat differences than to differences in fishing method.
The numbers and biomass of bycatch species taken in the creel fishery varied among areas, probably largely reflecting differences in community composition in different habitats. However, there is some evidence of a gear effect, with the presence of escape gaps leading to a possible reduction in catches of some crab species. The bycatch is low in comparison with published values for the trawl fishery. There is some mortality of discarded bycatch from seabirds, which varies with location and wind speed, but a preliminary study indicated that discard survival is higher than in trawl fisheries.
The effects of ghost fishing were investigated experimentally at two sites and the results suggested that lost creels do not constitute a serious issue in this fishery. Although not very efficient, Nephrops creels appear to be highly selective for the target species. The mortality of non-target species caught in lost creels was low. Most individuals of non-target species escaped and there was evidence that for some species, escape gaps in the creel assisted this. There was no evidence of a ‘re-baiting’ effect from animals dying within the creels. These findings, together with those on bycatch and physical impacts, show that although some environmental impacts can be demonstrated, Nephrops creels have little detrimental impact on the benthic environment.
The management measures (both statutory and voluntary) currently applied in the Torridon area are discussed and considered in relation to other areas. It is concluded that each area needs to be considered on its own merit, taking account of the biological characteristics of the stock, and considering management issues on a local scale.
The research described in this report investigated aspects of the sustainability and environmental impacts of creel fishing for Norway lobster, Nephrops norvegicus, in Loch Torridon and the Inner Sound in northwest Scotland. Creel fishing for Norway lobster, Nephrops, is thought to be less environmentally damaging than trawling, but there was little previous empirical information on this.
In 2001, a fishery order was made by Scottish Ministers, creating zones for different fishing methods in the Torridon area, including a mobile gear exclusion zone, a creel exclusion zone, a zone closed to mobile gear for 6 months per year and a mixed gear zone. There is also an area in the Inner Sound reserved for testing underwater weapons systems, which has been closed to all fishing since 1975. Additionally, the majority of local creel fishers operating in the creel-only zone abide by an agreed set of voluntary conservation measures. The fishery order is due to be reviewed in 2006 and the present study aimed to provide information to contribute to the evaluation of the effectiveness of the creel-only zone and the voluntary conservation measures.
The creel catch of Nephrops shows strong seasonal trends that reflect the patterns of moulting and reproduction in this species. Peak female catch was observed in the early spring, following moulting and mating, with catch rates becoming low after spawning in autumn. The catch rate of males peaked around February following moulting. Of those animals caught, males were larger than females, providing a partial explanation for observed seasonal variations in catch size distribution. Spatial variations in catches and the size-distributions of constituent animals were evident both among and within fisheries. Microscale mapping of fishing effort and landings, using logbooks and GPS-linked data loggers, enabled this to be resolved in detail in some areas. There is some evidence that the management measures applied by a sector of the creel fishermen in the Torridon area has had a positive effect on the stock within this area.
Behavioral studies both in the wild and in aquaria have shown that the catchability of Nephrops by creeling is low (initial results show around 1 entry per 100 approaches). The capture process could be considered as a sequence of events, at each stage of which individual Nephrops could progress towards creel entry, or move away. The role of Nephrops behaviour at each stage of the capture process was evaluated. In addition, it appeared that inter- (crabs) and intra-specific interactions deterred Nephrops from entering a creel.
Environmental damage from creeling appears to be low. The most vulnerable species in the area appears to be the large sea pen Funiculina quadrangularis and its associated brittle star Asteronyx loveni. The density of F. quadrangularis was low in the trawl zone, but numbers of F. quadrangularis seem to be little affected by creel fishing. However, there was some evidence that creel fishing may have impacted the brittle star A. loveni. Differences in species composition of benthic epifauna between fishing zones (i.e. trawled versus creeled areas) were observed, but were probably more related to habitat differences than to differences in fishing method.
The numbers and biomass of bycatch species taken in the creel fishery varied among areas, probably largely reflecting differences in community composition in different habitats. However, there is some evidence of a gear effect, with the presence of escape gaps leading to a possible reduction in catches of some crab species. The bycatch is low in comparison with published values for the trawl fishery. There is some mortality of discarded bycatch from seabirds, which varies with location and wind speed, but a preliminary study indicated that discard survival is higher than in trawl fisheries.
The effects of ghost fishing were investigated experimentally at two sites and the results suggested that lost creels do not constitute a serious issue in this fishery. Although not very efficient, Nephrops creels appear to be highly selective for the target species. The mortality of non-target species caught in lost creels was low. Most individuals of non-target species escaped and there was evidence that for some species, escape gaps in the creel assisted this. There was no evidence of a ‘re-baiting’ effect from animals dying within the creels. These findings, together with those on bycatch and physical impacts, show that although some environmental impacts can be demonstrated, Nephrops creels have little detrimental impact on the benthic environment.
The management measures (both statutory and voluntary) currently applied in the Torridon area are discussed and considered in relation to other areas. It is concluded that each area needs to be considered on its own merit, taking account of the biological characteristics of the stock, and considering management issues on a local scale.
| Original language | English |
|---|---|
| Place of Publication | Battleby, Perth |
| Publisher | Scottish Natural Heritage |
| Commissioning body | Scottish Natural Heritage |
| Number of pages | 167 |
| Publication status | Published - 2006 |
Keywords
- Nephrops, Norway lobster, creel fishery, environmental impact, sustainability, protected area, rural community
